HK40018074B

HK40018074B - Method and apparatus for narrowband time-division duplex frame structure for narrowband communications

Info

Publication number: HK40018074B
Application number: HK62020008397.5A
Authority: HK
Inventors: A·斯里德哈兰; K·巴塔德; M·钱德拉塞卡尔; G·索米切蒂; A·里科阿尔瓦里尼奥; X·F·王
Original assignee: 高通股份有限公司
Priority date: 2017-02-14
Filing date: 2018-02-09
Publication date: 2021-04-23

Description

Narrow-band time division duplex frame structure method and device for narrow-band communication

Cross Reference to Related Applications

The present application claims the benefits of indian application No.201741005220 entitled "narrow TIME-width DUP L EX FRAME STRUCTURE FOR narrow communication", filed on 14.2.2017, indian application No.201741005360 entitled "narrow TIME-width DUP L EX FRAME STRUCTURE FOR narrow communication", filed on 15.2.2017, and united states patent application No.15/707,774 entitled "narrow TIME-width DUP L EX FRAME STRUCTURE FOR narrow communication", filed on 18.9.2017, the entire contents of which are expressly incorporated herein by reference.

Technical Field

The present disclosure relates generally to communication systems, and more particularly to narrowband Time Division Duplex (TDD) frame structures for narrowband communication.

Background

Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasting. Typical wireless communication systems may employ multiple-access techniques capable of supporting communication with multiple users by sharing the available system resources. Examples of such multiple-access techniques include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, Orthogonal Frequency Division Multiple Access (OFDMA) systems, single carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.

One example telecommunication standard is the 5G New Radio (NR). 5G NR is part of a continuous mobile broadband evolution promulgated by the third Generation partnership project (3GPP) to meet latency, reliability, security, scalability (e.g., utilizing the Internet of things (IoT)) and other requirements.some aspects of the 5G NR may be based on the 4G Long term evolution (L TE) standard.there is a need for further improvements in the 5G NR technology.

One example of narrowband communication is Narrowband (NB) IoT (NB-IoT) communication, which is limited to a single Resource Block (RB) of the system bandwidth (e.g., 180 kHz). another example of narrowband communication is enhanced machine type communication (eMTC), which is limited to six RBs of the system bandwidth (e.g., 1.08 MHz).

NB-IoT communications and eMTC may reduce device complexity, enable years of battery life, and provide deeper coverage to reach challenging locations (e.g., deep inside buildings). Since the coverage provided by narrowband communications may include reaching challenging locations (e.g., smart gas meters located in basements of buildings), there is an increased likelihood that one or more transmissions will not be received correctly. Thus, repeated transmissions may be used in narrowband communications to increase the probability that the transmission will be correctly decoded by the receiver device. The TDD frame structure may support repeated transmissions because the TDD frame structure has an increased number of consecutive downlink and/or uplink subframes compared to a Frequency Division Duplex (FDD) frame structure. There is a need to support a narrowband TDD frame structure for narrowband communications.

Disclosure of Invention

The following presents a simplified summary of one or more aspects in order to provide a basic understanding of such aspects. This summary is not an extensive overview of all contemplated aspects, and is intended to neither identify key or critical elements of all aspects nor delineate the scope of any or all aspects. Its sole purpose is to present some concepts of one or more aspects in a simplified form as a prelude to the more detailed description that is presented later.

One example of narrowband communication is NB-IoT communication, which is limited to a single RB of the system bandwidth, e.g., 180khz another example of narrowband communication is eMTC, which is limited to six RBs of the system bandwidth, e.g., 1.08 MHz.

NB-IoT communications and eMTC may reduce device complexity, enable years of battery life, and provide deeper coverage to reach challenging locations (e.g., deep inside buildings). However, as the coverage provided by the narrowband communications may include reaching challenging locations (e.g., smart gas meters located in basements of buildings), the chances increase that one or more transmissions will not be correctly decoded by the receiver device. Thus, the narrowband communication may include a predetermined number of repeated transmissions to increase the chances of having the transmission correctly decoded by the receiver device. A narrowband communication system may use a TDD frame structure because some TDD frame configurations may include a greater number of consecutive uplink and/or downlink subframes that may be used for repeated transmissions than an FDD frame structure. There is a need for supporting narrowband communications using a narrowband TDD frame structure.

The present disclosure provides a mechanism for supporting one or more narrowband TDD frame structures for narrowband communications.

In one aspect of the disclosure, a method, computer-readable medium, and apparatus are provided. The apparatus may determine a bandwidth for narrowband communications. The apparatus may determine a narrowband TDD frame structure for the narrowband communication. In one aspect, the narrowband TDD frame structure may include at least one of: two or more consecutive downlink subframes, or one or more flexible subframes that may be configured as either downlink subframes or uplink subframes. The apparatus may communicate with a UE using the narrowband TDD frame structure determined for the narrowband communication.

In certain aspects, the apparatus may determine a TDD mode for narrowband communications. The apparatus may also determine a TDD frame structure for the narrowband communication from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure of the set of narrowband TDD frame structures may be configured as a downlink subframe. The apparatus may also transmit a Primary Synchronization Signal (PSS) using the at least one common subframe in the narrowband TDD frame structure determined for the narrowband communication.

In certain other aspects, the apparatus may determine a TDD mode for narrowband communications. The apparatus may also determine a narrowband TDD frame structure for the narrowband communication from a set of narrowband TDD frame structures. The apparatus may also transmit a PSS using the narrowband TDD frame structure determined for the narrowband communication. In one aspect, the set of PSS sequences may be associated with at least one of the TDD mode or the narrowband TDD frame structure determined for the narrowband communication.

In certain other aspects, the apparatus may determine a narrowband communication frame structure including FDD mode or TDD mode and determine a particular TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. The apparatus may determine a periodicity, a subframe number, and a transmission sequence associated with an SSS based at least in part on the narrowband TDD frame structure. The apparatus may transmit the SSS using the narrowband TDD frame structure determined for the narrowband communication. In an aspect, the SSS may be transmitted using the same subframe in at most every other frame.

In certain other aspects, the apparatus may determine a narrowband communication frame structure comprising an FDD frame structure or a TDD frame structure and determine a narrowband TDD frame structure configuration for narrowband communication from a set of narrowband TDD frame structure configurations. The apparatus may determine one or more narrowband carriers and subframes within the one or more narrowband carriers to transmit at least one of a BCH or a SIB1 based on the narrowband communication frame structure or the TDD frame structure configuration. The apparatus may transmit at least one of a PSS, a SSS, and a BCH or a SIB1 using the narrowband TDD frame structure determined for the narrowband communication. In an aspect, the carrier used to transmit the BCH and/or the SIB may be different from the carrier used to transmit one or more of the PSS or the SSS. In another aspect, the narrowband carrier used to transmit the BCH may be different from the narrowband carrier used to transmit one or more of the PSS or the SSS.

In certain other aspects, the apparatus may determine a narrowband TDD frame structure for narrowband communications. In one aspect, the narrowband TDD frame structure may include one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In certain other aspects, the apparatus may transmit a bitmap associated with the narrowband TDD frame structure to a UE. In an aspect, the bitmap may indicate one or more of: the set of downlink subframes, the set of uplink subframes, the set of special subframes, or the set of flexible subframes.

The apparatus may determine a narrowband TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In one aspect, the narrowband TDD frame structure may include a set of downlink subframes and special subframes. The apparatus may determine a set of narrowband carriers and a minimum set of subframes on the set of narrowband carriers based at least in part on the set of downlink subframes and special subframes on which NRS should be transmitted. The apparatus may transmit the NRS using the narrowband TDD frame structure determined for the narrowband communication.

To the accomplishment of the foregoing and related ends, the one or more aspects comprise the features hereinafter fully described and particularly pointed out in the claims. The following description and the annexed drawings set forth in detail certain illustrative features of the one or more aspects. These features are indicative, however, of but a few of the various ways in which the principles of various aspects may be employed and the present description is intended to include all such aspects and their equivalents.

Drawings

Fig. 1 is a diagram illustrating an example of a wireless communication system and an access network.

Fig. 2A, 2B, 2C, and 2D are diagrams illustrating L TE examples of D L, D L, U L, and U L channels within a D L, and U L frame structures, respectively.

Fig. 3 is a diagram illustrating an example of an evolved node b (enb) and User Equipment (UE) in an access network.

Fig. 4 is a diagram illustrating an example narrowband TDD frame structure, in accordance with certain aspects of the present disclosure.

Fig. 5A is a diagram of data flows for narrowband communications using a narrowband TDD frame structure, in accordance with certain aspects of the present disclosure.

Fig. 5B-5D are diagrams of data flows for narrowband communication using a narrowband TDD frame structure, according to certain aspects of the present disclosure.

Fig. 6 is a flow chart of a method of wireless communication.

Fig. 7 is a flow chart of a method of wireless communication.

Fig. 8 is a flow chart of a method of wireless communication.

Fig. 9 is a flow chart of a method of wireless communication.

Fig. 10 is a flow chart of a method of wireless communication.

Fig. 11 is a conceptual data flow diagram illustrating the data flow between different units/components in an exemplary apparatus.

Fig. 12 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Fig. 13 is a conceptual data flow diagram illustrating the data flow between different units/components in an exemplary apparatus.

Fig. 14 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Fig. 15 is a conceptual data flow diagram illustrating the data flow between different units/components in an exemplary apparatus.

Fig. 16 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Fig. 17 is a conceptual data flow diagram illustrating the data flow between different units/components in an exemplary apparatus.

Fig. 18 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Fig. 19 is a conceptual data flow diagram illustrating the data flow between different units/components in an exemplary apparatus.

Fig. 20 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Fig. 21 is a diagram of data flows for narrowband communications using a narrowband TDD frame structure, in accordance with certain aspects of the present disclosure.

Fig. 22 is a flow chart of a method of wireless communication.

Fig. 23 is a conceptual data flow diagram illustrating the data flow between different units/components in an exemplary apparatus.

Fig. 24 is a diagram illustrating an example of a hardware implementation for an apparatus employing a processing system.

Fig. 25 is a flow chart of a method of wireless communication.

Detailed Description

The detailed description set forth below in connection with the appended drawings is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. It will be apparent, however, to one skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

Several aspects of a telecommunications system will now be presented with reference to various apparatus and methods. These apparatus and methods are described in the following detailed description and illustrated in the accompanying drawings by various blocks, components, circuits, processes, algorithms, etc. (collectively referred to as "elements"). These elements may be implemented using electronic hardware, computer software, or any combination thereof. Whether such elements are implemented as hardware or software depends upon the particular application and design constraints imposed on the overall system.

By way of example, an element or any portion of an element or any combination of elements may be implemented as a "processing system" including one or more processors, examples of which include microprocessors, microcontrollers, Graphics Processing Units (GPUs), Central Processing Units (CPUs), application processors, Digital Signal Processors (DSPs), Reduced Instruction Set Computing (RISC) processors, systems on chip (socs), baseband processors, Field Programmable Gate Arrays (FPGAs), programmable logic devices (P L D), state machines, gated logic, discrete hardware circuits, and other suitable hardware.

Thus, in one or more example embodiments, the functions described may be implemented in hardware, software, or any combination thereof. If implemented in software, the functions may be stored on or encoded on a computer-readable medium as one or more instructions or code. Computer readable media includes computer storage media. A storage media may be any available media that can be accessed by a computer. By way of example, and not limitation, such computer-readable media can comprise Random Access Memory (RAM), Read Only Memory (ROM), electrically erasable programmable ROM (eeprom), optical disk storage, magnetic disk storage, other magnetic storage devices, combinations of the above types of computer-readable media, or any other medium that can be used to store computer-executable code in the form of instructions or data structures and that can be accessed by a computer.

Fig. 1 is a diagram illustrating an example of a wireless communication system and an access network 100. A wireless communication system, also referred to as a Wireless Wide Area Network (WWAN), includes a base station 102, a UE 104, and an Evolved Packet Core (EPC) 160. Base station 102 may include a macro cell (high power cellular base station) and/or a small cell (low power cellular base station). The macro cell includes a base station. Small cells include femtocells, picocells and microcells.

Base stations 102, collectively referred to as evolved Universal Mobile Telecommunications System (UMTS) terrestrial radio access network (E-UTRAN), interface with EPC160 over backhaul links 132 (e.g., S1 interface). Base station 102 may perform one or more of the following functions, among others: transmission of user data, radio channel encryption and decryption, integrity protection, header compression, mobility control functions (e.g., handover, dual connectivity), inter-cell interference coordination, connection establishment and release, load balancing, distribution for non-access stratum (NAS) messages, NAS node selection, synchronization, Radio Access Network (RAN) sharing, Multimedia Broadcast Multicast Service (MBMS), user and device tracking, RAN Information Management (RIM), paging, positioning, and delivery of warning messages. Base stations 102 may communicate with each other directly or indirectly (e.g., through EPC 160) through backhaul link 134 (e.g., X2 interface). The backhaul link 134 may be wired or wireless.

The base station 102 may communicate wirelessly with the UE 104. Each of the base stations 102 may provide communication coverage for a respective geographic coverage area 110. There may be overlapping geographic coverage areas 110. For example, the small cell 102 'may have a coverage area 110' that overlaps with the coverage areas 110 of one or more macro base stations 102. A network that includes both small cells and macro cells may be referred to as a heterogeneous network. The heterogeneous network may also include a home evolved node b (enb) (henb), which may provide services to a restricted group referred to as a Closed Subscriber Group (CSG). The communication link 120 between base station 102 and UE 104 may include uplink (also referred to as reverse link) transmissions from UE 104 to base station 102 and/or downlink (also referred to as forward link) transmissions from base station 102 to UE 104. The communication link 120 may use multiple-input multiple-output (MIMO) antenna techniques including spatial multiplexing, beamforming, and/or transmit diversity. The communication link may be through one or more carriers. The base station 102/UE 104 may use a spectrum of up to a bandwidth of Y MHz (e.g., 5, 10, 15, 20, 100MHz) per carrier allocated in a carrier aggregation of up to a total of yxmhz (x component carriers) for transmissions in each direction. The carriers may or may not be adjacent to each other. The allocation of carriers may be asymmetric with respect to the downlink and uplink (e.g., more or fewer carriers may be allocated for the downlink than for the uplink). The component carriers may include a primary component carrier and one or more secondary component carriers. The primary component carrier may be referred to as a primary cell (PCell), and the secondary component carrier may be referred to as a secondary cell (SCell).

Some UEs 104 may communicate with each other using a device-to-device (D2D) communication link 192D 2D communication link 192 may use D L/U L WWAN spectrum D2D communication link 192 may use one or more sidelink channels, e.g., a Physical Sidelink Broadcast Channel (PSBCH), a Physical Sidelink Discovery Channel (PSDCH), a Physical Sidelink Shared Channel (PSSCH), and a Physical Sidelink Control Channel (PSCCH). D2D communication may be over a wide variety of wireless D2D communication systems, e.g., Flash L inQ, WiMedia, Bluetooth, ZigBee, Wi-Fi based 802.11 standards, L TE, or NR.

The wireless communication system may also include a Wi-Fi Access Point (AP)150 that communicates with a Wi-Fi Station (STA)152 via a communication link 154 in the 5GHz unlicensed spectrum. When communicating in the unlicensed spectrum, the STA 152/AP 150 may perform a Clear Channel Assessment (CCA) prior to communicating to determine whether a channel is available.

The small cell 102' may operate in licensed and/or unlicensed spectrum. When operating in unlicensed spectrum, small cell 102' may employ NR and use the same 5GHz unlicensed spectrum as used by Wi-Fi AP 150. Small cells 102' employing NR in unlicensed spectrum may improve coverage and/or increase capacity of the access network.

The g node b (gnb)180 may operate in millimeter wave (mmW) frequencies and/or near mmW frequencies to communicate with the UE 104. When gNB 180 operates in mmW or near mmW frequencies, gNB 180 may be referred to as a mmW base station. Extremely High Frequency (EHF) is a portion of the RF electromagnetic spectrum. The EHF has a range of 30GHz to 300GHz and has a wavelength between 1 millimeter and 10 millimeters. The radio waves in this frequency band may be referred to as millimeter waves. Near mmW can be extended down to frequencies of 3GHz with a wavelength of 100 mm. The ultra-high frequency (SHF) band extends between 3GHz and 30GHz, also known as centimeter waves. Communications using the mmW/near mmW radio frequency band have extremely high path loss and short range. The mmW base station 180 may utilize beamforming 184 with the UE 104 to compensate for extremely high path loss and short range.

The EPC160 may include a Mobility Management Entity (MME)162, other MMEs 164, a serving gateway 166, a Multimedia Broadcast Multicast Service (MBMS) gateway 168, a broadcast multicast service center (BM-SC)170, and a Packet Data Network (PDN) gateway 172. the MME 162 may communicate with a Home Subscriber Server (HSS) 174. the MME 162 is a control node that handles signaling between the UE 104 and the EPC 160. in general, the MME 162 provides bearer and connection management. all user Internet Protocol (IP) packets are transmitted through the serving gateway 166. the serving gateway 116 is itself connected to the PDN gateway 172. the PDN gateway 172 provides UE IP address allocation and other functions. the PDN gateway 172 and BM-SC 170 are connected to IP services 176. the IP services 176 may include the Internet, Intranet, IP Multimedia Subsystem (IMS), PS streaming services, and/or other IP services. the BM-SC 170 may provide functions for MBMS user service provisioning and delivery.

A base station may also be referred to as a gbb, a node B, an evolved node B (enb), an access point, a base transceiver station, a radio base station, a radio transceiver, a transceiver function, a Basic Service Set (BSS), an Extended Service Set (ESS), or some other suitable terminology. Base station 102 provides an access point for UE 104 to EPC 160. Examples of UEs 104 include a cellular phone, a smart phone, a Session Initiation Protocol (SIP) phone, a laptop, a Personal Digital Assistant (PDA), a satellite radio, a global positioning system, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, a tablet device, a smart device, a wearable device, a vehicle, an electricity meter, a gas pump, a toaster, or any other device with similar functionality. Some of the UEs 104 may be referred to as IoT devices (e.g., parking meters, gas pumps, toasters, vehicles, etc.). UE 104 may also be referred to as a station, mobile station, subscriber station, mobile unit, subscriber unit, wireless unit, remote unit, mobile device, wireless communication device, remote device, mobile subscriber station, access terminal, mobile terminal, wireless terminal, remote terminal, handset, user agent, mobile client, or some other suitable terminology.

Referring again to fig. 1, in certain aspects, the base stations 102, 180 and/or the UE 104 may be configured to support one or more narrowband TDD frame structures (198) for narrowband communications, e.g., as described in connection with any of fig. 4-25.

Fig. 2A is a diagram 200 showing an example of a D L frame structure in a L TE, fig. 2B is a diagram 230 showing an example of a channel within a D L1 frame structure in a L TE, fig. 2C is a diagram 250 showing an example of a U L frame structure in a L TE, fig. 2D is a diagram 280 showing an example of a channel within a U L frame structure in a L TE, other wireless communication technologies may have different frame structures and/or different channels, in L TE, a frame (10ms) may be divided into 10 equally sized sub-frames, each sub-frame may include two consecutive slots, two slots may be represented using a resource grid, each slot including one or more time-concurrent Resource Blocks (RBs) (also referred to as physical RBs) (prb) the resource grid is divided into a plurality of Resource Elements (REs) in L TE, for a common cyclic prefix RB, 12 consecutive sub-carriers in the frequency domain and 7 consecutive symbols in the time domain (L-84 symbols), for a total number of contiguous cyclic prefixes carried by a number of subcarriers in the common RB, 636-62, for a common cyclic prefix RB, and 6856 symbols in the time domain.

As shown in fig. 2A, some of the REs carry D L reference (pilot) signals (D L-RS) for channel estimation at the UE D L-RS may include cell-specific reference signals (CRS) (also sometimes referred to as common RS), UE-specific reference signals (UE-RS), and channel state information reference signals (CSI-RS). fig. 2A shows CRS for antenna ports 0, 1, 2, and 3 (indicated as R, respectively)₀、R₁、R₂And R₃) UE-RS (indicated as R) for antenna port 5₅) And CSI-RS (indicated as R) for antenna port 15 fig. 2B shows an example of various channels within the D L subframe of the frame Physical Control Format Indicator Channel (PCFICH) is within symbol 0 of slot 0 and carries Control Format Indicator (CFI) indicating whether the Physical Downlink Control Channel (PDCCH) occupies 1, 2 or 3 symbols (fig. 2B shows PDCCH occupying 3 symbols), each CCE includes nine RE groups (REGs), each REG includes four consecutive re.ues in one OFDM symbol, which may be configured with UE-specific enhanced PDCCH ePDCCH (dcch) also carrying DCI, two RB pairs (fig. 2B) each including one RB pair (ARQ) indicator channel (PHICH) is also within symbol 0 of slot 0, and two RB pairs (fig. 2B) are shown, each subset including one RB pair, physical hybrid automatic repeat request (ARQ) indicator channel (HARQ) indicator channel (PHICH) is determined within symbol 0 of slot 0 and based on physical uplink HARQ synchronization indicator channel (PUSCH) and Physical Downlink Control Channel (PDCCH) identity, which may be used to determine, within a primary HARQ synchronization subframe, which may be carried within a primary HARQ-RS layer (PUSCH) synchronization subframe, which may be used to determine, based on the Physical Control Format Indicator Channel (PCFICH) and primary control format indicator channel (PDCCH) within the primary control channel (PDCCH) within symbol 0, which may be used to determine, which may be used within the primary control format indicator channel (PDCCH) and primary control channel (PUSCH) to carry the primary control format indicator channel (PUSCH) to carry the primary control channel (PDCCH) to determine, which may be used within symbol (PUSCH) to carry the primary control format indicator channel (PUSCH) within symbol (PUSCH) of the primary RS) of the synchronization layer (PUSCH) and primary physical downlink control channel (PUSCH) within symbolThe Physical Broadcast Channel (PBCH) is within symbols 0, 1, 2, 3 in slot 1 of subframe 0 of the frame and carries a Master Information Block (MIB) — the MIB provides the number of RBs in the D L system bandwidth, the PHICH configuration, and the System Frame Number (SFN) — the Physical Downlink Shared Channel (PDSCH) carries user data, broadcast system information (e.g., System Information Blocks (SIBs)) not sent over the PBCH, and paging messages.

As shown in fig. 2C, some of the REs carry demodulation reference signals (DM-RS) for channel estimation at the eNB, in addition, the UE may transmit Sounding Reference Signals (SRS) in the last symbol of a subframe, the SRS may have a comb structure, and the UE may transmit SRS on one of the comb fingers, which may be used by the eNB for channel quality estimation to enable frequency-dependent scheduling on U L fig. 2D shows an example of various channels within the U L subframe of a frame, PRACH may be within one or more subframes within a frame, based on a physical random access channel (BSR) configuration, the PRACH may include six consecutive RB pairs within a subframe, the PRACH allows the UE to perform initial system access and achieve U L synchronization, a Physical Uplink Control Channel (PUCCH) may be located on the edge of the U L system bandwidth.

FIG. 3 is a block diagram of an eNB 310 in communication with a UE 350 in an access network, in D L IP packets from EPC160 may be provided to a controller/processor 375. controller/processor 375 implements layer 3 and layer 2 functions, layer 3 includes a Radio Resource Control (RRC) layer, and layer 2 includes a Packet Data Convergence Protocol (PDCP) layer, a radio link control (R L C) layer, and a Medium Access Control (MAC) layer controller/processor 375 provides RRC layer functions associated with broadcast of system information (e.g., MIB, SIB), RRC connection control (e.g., RRC connection paging, RRC connection establishment, RRC connection modification, and RRC connection release), inter-Radio Access Technology (RAT) mobility, and measurement configuration for UE measurement reporting, PDCP layer functions associated with header compression/decompression, security (ciphering, deciphering, integrity protection, integrity verification), and handover support functions, R L C layer functions associated with upper layer functions, a transport unit (R6754) for service data, PDU, and MAC-level data block re-multiplexing, PDU, MAC-scheduling, PDU scheduling, and MAC-layer scheduling by a transport channel ordering, PDU, a transport unit, a retransmission, a PDU, a retransmission channel, a PDU, a retransmission buffer, a retransmission control, and a MAC-based on HARQ-level scheduling information.

The Transmit (TX) processor 316 and the Receive (RX) processor 370 perform layer 1 functions associated with various signal processing functions. Layer 1, which includes the Physical (PHY) layer, may include error detection on transport channels, Forward Error Correction (FEC) encoding/decoding of transport channels, interleaving, rate matching, mapping onto physical channels, modulation/demodulation of physical channels, and MIMO antenna processing. The TX processor 316 processes mappings to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M-quadrature amplitude modulation (M-QAM)). The coded and modulated symbols may then be split into parallel streams. Each stream may then be mapped to OFDM subcarriers, multiplexed with reference signals (e.g., pilots) in the time and/or frequency domain, and then combined together using an Inverse Fast Fourier Transform (IFFT) to produce a physical channel carrying a time-domain OFDM symbol stream. The OFDM streams are spatially precoded to produce a plurality of spatial streams. The channel estimates from channel estimator 374 may be used to determine coding and modulation schemes, as well as for spatial processing. The channel estimates may be derived from reference signals and/or channel condition feedback transmitted by the UE 350. Each spatial stream may then be provided to a different antenna 320 via a separate transmitter 318 TX. Each transmitter 318TX may modulate an RF carrier with a respective spatial stream for transmission.

At the UE 350, each receiver 354RX receives a signal through its respective antenna 352. Each receiver 354RX recovers information modulated onto an RF carrier and provides the information to a Receive (RX) processor 356. The TX processor 368 and the RX processor 356 implement layer 1 functions associated with various signal processing functions. The RX processor 356 may perform spatial processing on the information to recover any spatial streams destined for the UE 350. If multiple spatial streams are destined for the UE 350, they may be combined into a single OFDM symbol stream by the RX processor 356. The RX processor 356 then transforms the OFDM symbol stream from the time-domain to the frequency-domain using a Fast Fourier Transform (FFT). The frequency domain signal comprises a separate OFDM symbol stream for each subcarrier of the OFDM signal. The symbols on each subcarrier and the reference signal are recovered and demodulated by determining the most likely signal constellation points transmitted by the eNB 310. These soft decisions may be based on channel estimates computed by channel estimator 358. The soft decisions are then decoded and deinterleaved to recover the data and control signals originally transmitted by the eNB 310 on the physical channel. The data and control signals are then provided to a controller/processor 359, which controller/processor 359 implements layer 3 and layer 2 functions.

In U L, controller/processor 359 can be associated with memory 360 that stores program codes and data, memory 360 can be referred to as a computer-readable medium, provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, and control signal processing to recover IP packets from EPC 160.

Similar to the functionality described in connection with the D L transmission by eNB 310, controller/processor 359 provides RRC layer functionality associated with system information (e.g., MIB, SIB) acquisition, RRC connection, and measurement reporting, PDCP layer functionality associated with header compression/decompression, and security (ciphering, deciphering, integrity protection, integrity verification), R L C layer functionality associated with transmission of upper layer PDUs, error correction by ARQ, concatenation, segmentation, and reassembly of R L C SDUs, re-segmentation of R L C data PDUs, and re-ordering of R L C data PDUs, and MAC layer functionality associated with mapping between logical channels and transport channels, multiplexing of MAC SDUs onto TBs, demultiplexing of MAC SDUs from TBs, scheduling information reporting, error correction by HARQ, priority handling, and logical channel prioritization.

The TX processor 368 may use channel estimates derived by a channel estimator 358 from a reference signal or feedback transmitted by the eNB 310 to select an appropriate coding and modulation scheme and to facilitate spatial processing. The spatial streams generated by the TX processor 368 may be provided to different antennas 352 via separate transmitters 354 TX. Each transmitter 354TX may modulate an RF carrier with a respective spatial stream for transmission.

At the eNB 310, the U L transmissions are processed in a manner similar to that described in connection with the receiver function at the UE 350. each receiver 318RX receives signals through its respective antenna 320. each receiver 318RX recovers information modulated onto an RF carrier and provides the information to an RX processor 370.

The controller/processor 375 may be associated with a memory 376 that stores program codes and data the memory 376 may be referred to as a computer readable medium in U L the controller/processor 375 provides demultiplexing between transport and logical channels, packet reassembly, deciphering, header decompression, control signal processing to recover IP packets from the UE 350 the IP packets from the controller/processor 375 may be provided to the EPC160 the controller/processor 375 is also responsible for supporting error detection for HARQ operations using ACK and/or NACK protocols.

The present disclosure provides mechanisms for supporting one or more narrowband TDD frame structures for narrowband communications, e.g., as described below with reference to fig. 5A-5D.

Fig. 4 is a diagram illustrating a narrowband TDD frame structure 400 that may be used for narrowband communications, according to certain aspects of the present disclosure. In an aspect, the narrowband TDD frame structure 400 for narrowband communications may be determined according to a set of narrowband TDD frame structures (e.g., configuration 0-configuration n) listed in table 410. In certain aspects, the base station may determine the narrowband TDD frame structure based on higher layer signaling (e.g., RRC messaging) received from the network. In certain aspects, a base station may determine a narrowband TDD frame structure based on channel conditions.

In one aspect, the narrowband TDD frame structure 400 may include a 10ms radio frame split into two half-frames, each half-frame being 5ms long. A half frame may be further split into five subframes, each 1ms long. The narrowband TDD frame structure 400 can be any one of the narrowband configurations listed in table 410.

A switching period refers to the time that a UE uses to switch between monitoring downlink subframes (e.g., for downlink transmissions from a base station) and using uplink subframes to send transmissions (or vice versa). Depending on the determined narrowband TDD frame structure 400, the switching period may be 5ms, 10ms, or greater than 10ms (e.g., 20 ms). For a narrowband TDD frame structure 412 with a 5ms switching period, the Special Subframes (SSFs) may be located in both half-frames of the narrowband TDD frame structure 400. For a narrowband TDD frame structure 414 with a switching period of 10ms, the special subframe may be located in the first half frame and not in the second half frame. For a narrowband TDD frame structure 416 with a switching period greater than 10ms, no special subframes may be needed, as more than the entire frame may be used to perform the switching. In the narrowband TDD frame structures 412, 414 (e.g., configurations 0, 1, 2, 3, 4, 5, and 6) including special subframes, the downlink pilot time slots (DwPTS) in subframes 0 and 5 and the special subframes may be reserved for downlink transmission. Additionally and/or alternatively, in the narrowband TDD frame structures 412, 414 that include a special subframe, an uplink pilot time slot (UpPTS) in the special subframe and a subframe immediately following the special subframe may be reserved for uplink transmissions.

When operating in an in-band mode and/or a guard band mode, the narrowband TDD frame structure 400 may reuse certain L TE TDD frame structures (e.g., configurations 0, 1, 2, 3, 4, 5, 6) — when operating in a standalone mode, some subframes in the narrowband TDD frame structure 400 may be marked as flexible subframes (e.g., configurations m and n) and may be used by a UE as downlink subframes or uplink subframes according to a current grant received from a base station.

In certain aspects, a subset of the narrowband TDD configurations listed in table 410 in fig. 4 may be used to support narrowband communications. For example, configuration 0 may not be suitable for narrowband communication because configuration 0 only has two downlink subframes and, therefore, may not support repeated transmissions for the UE. In certain aspects, narrowband communications using a narrowband TDD frame structure may be supported only in an in-band mode and/or a guard-band mode (e.g., but not in a standalone mode). In certain other aspects, narrowband communications using a narrowband TDD frame structure may be supported in an in-band mode, a guard-band mode, and an independent mode.

Multiple narrowband downlink carriers and multiple narrowband uplink carriers may be used to enhance narrowband communications between the base station and the UE. Among these carriers, the narrowband anchor carrier may be used to provide synchronization, system information, paging, data, and control for multi-carrier enabled UEs. When a narrowband anchor carrier is used, overhead narrowband system information may be reduced. For example, synchronization and paging for a cell may not be provided on all narrowband carriers. A narrowband carrier that does not provide synchronization and/or paging may be referred to as a narrowband non-anchor carrier. Coordination between base stations for selecting an anchor carrier that mitigates interference and coordination between base stations for transmit power control for non-anchor carriers may provide additional network performance advantages.

Information indicating the determined narrowband TDD frame structure 400 may be sent from the base station to the UE using narrowband pss (npss), narrowband sss (nsss), narrowband pbch (npbch), and/or SIBs (e.g., using a narrowband anchor carrier).

For the in-band mode and the guard-band mode, a narrowband anchor carrier for narrowband communications (e.g., using a narrowband TDD frame structure) may be located in an RB pair for downlink transmissions from the base station to the UE. In certain aspects, the UE may monitor one RB at any given time. In one example, SIBs and/or NPBCH may arrive at the UE in the first RB of a RB pair, and NPSS and/or NSSS may arrive at the UE in the second RB of the pair. In another example, the SIB may arrive at the UE in the first RB of the RB pair, and the NPSS, NSSS, and/or NPBCH may arrive at the UE in the second RB of the pair. The position of one RB may be determined (e.g., implicitly derived) by the UE based on the position of the other RB in the pair or based on the position of a different RB in a different RB pair.

In addition, the UE may send uplink transmissions using the RB pair. In certain aspects, the UE may determine which of the RB pairs to use for uplink transmissions based on signaling received from the base station (e.g., higher layer signaling). In certain other aspects, the UE may determine which RB pairs to use for uplink transmissions based on the type of uplink channel being transmitted (e.g., PRACH and ACK/NACK using one RB and PUSCH using another RB). In certain other aspects, the UE may determine which RB pairs to use for uplink transmissions based on the coverage level and/or channel conditions.

Fig. 5A is a diagram illustrating a data flow 500 that may be used for narrowband communications in accordance with certain aspects of the present disclosure. For example, data flow 500 may be performed by base station 504 and/or UE 506. The base station 504 may correspond to, for example, base stations 102, 180, eNB 310, devices 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'. The UE506 may correspond to, for example, the UE 104, 350, 1150, 1350, 1550, 1750, 1950, 2350. In addition, the base station 504 and the UE506 may be configured to communicate using narrowband communications 509 (e.g., NB-IoT and/or eMTC). For example, the UE506 may be an NB-IoT device and/or an eMTC device. In fig. 5A, optional operations are indicated by dashed lines.

Referring to fig. 5A, the base station 504 may operate 501 in a standalone mode, and the base station may use a standalone mode bandwidth (e.g., 1.08MHz or 180kHz) different from a bandwidth (e.g., 1.4MHz, 3MHz, 5MHz, 10MHz, 15MHz, 20MHz, 100MHz, etc.) available for L TE communications 509 for narrowband communications.

In certain aspects, the base station 504 may determine 503 a narrowband TDD frame structure for narrowband communications 509.

In certain other aspects, the base station 504 may determine 503 a narrowband TDD frame structure from a subset of configurations from the table 410 of fig. 4. For example, base station 504 can determine 503 narrowband TDD frame structures from configurations 1, 2, 3, 4, 5, m, and/or n. In certain aspects, configurations 0 and 6 may not be used for the narrowband TDD frame structure because configurations 0 and 6 have fewer downlink subframes than other configurations and, therefore, may not support repeated transmissions.

When the base station 504 repeats the downlink transmission, the base station 504 can select a narrowband TDD frame structure having at least a minimum number of downlink subframes (e.g., at least three downlink subframes) such that the downlink transmission can be repeated in each of the downlink subframes.

In certain other aspects, the base station 504 may determine 503 a narrowband TDD frame structure for narrowband communications 509 based on a switching period used by the base station 504 and/or the UE506 to switch from transmitting on downlink subframes to monitoring uplink subframes (and vice versa). for example, when the switching period used by the base station 504 and/or the UE506 is longer than the switching period in the L TE TDD frame structure (e.g., configurations 0, 1, 2, 3, 4, 5, and 6), the base station 504 may select configuration m or n because the switching periods for configurations m and n are both greater than 10ms (e.g., 20 ms).

In a first example, the narrowband TDD frame structure determined by base station 504 can be configuration n (see, e.g., fig. 4). Configuration n may include a plurality of flexible subframes, each of which may be dynamically configured by base station 504 as a downlink subframe, an uplink subframe, or a special subframe. Configuration n may provide flexibility to the base station 504 with downlink or uplink transmissions (e.g., based on channel conditions) in order to increase the chances that the UE506 decodes the transmission correctly.

In a second example, the narrowband TDD frame structure determined by base station 504 can be one of configurations 3, 4, 5, m, or n (e.g., see fig. 4). The narrowband TDD frame structures associated with configurations 3, 4, 5, m, and n each include at least three downlink subframes (e.g., the flexible subframes in configuration n may be dynamically configured by base station 504 such that the TDD frame structure has three or more downlink subframes). Using a narrowband TDD frame structure with at least three downlink subframes may enable base station 504 to transmit NPSS, NSSS, and NPBCH in different subframes of the same radio frame, as described below with reference to fig. 5B-5D. In certain aspects, the repetition of NPSS, NSSS, and NPBCH may be achieved by repeating NPSS, NSSS, and NPBCH over multiple symbols of the same subframe. The SIB507 may also be transmitted in a different subframe than the subframe used to transmit the NSSS 505 if configuration 4, 5, m, or n (e.g., a configuration with or configurable with four downlink subframes) is determined to be used as the narrowband TDD frame structure. For example, assuming the base station 504 determines that the narrowband TDD frame structure is configuration 5, the base station 504 may send NSSS 505 in subframe 5 and SIB507 in subframe 7.

In certain aspects, the base station 504 may repeat downlink transmissions using at least three consecutive downlink subframes. If the narrowband TDD frame structure is used for repeated downlink transmissions having less than three consecutive downlink subframes (e.g., configurations 0, 1, and 2 in fig. 4), the duration within which the repeated transmissions are transmitted may be increased compared to the duration of the same number of repetitions transmitted using a narrowband TDD frame structure having at least three consecutive downlink subframes. For example, the duration may be increased by the presence of uplink subframes and/or unused flexible subframes located between downlink subframes used for repeated transmissions. Accordingly, the likelihood that channel conditions may change on repeated transmissions using a narrowband TDD frame structure having less than three consecutive downlink subframes may be increased compared to repeated transmissions using a narrowband TDD frame structure having at least three consecutive downlink subframes. Therefore, it is unlikely that the UE506 will combine repeated transmissions received in a narrowband TDD frame structure with fewer than three consecutive downlink subframes.

Fig. 5B-5D illustrate data flows 510 that may be used for narrowband communication in accordance with certain aspects of the present disclosure. For example, data flow 500 may be performed by base station 504 and/or UE506 (e.g., base station 504 and UE506 in fig. 5A). The base station 504 may correspond to the base station 102, 180, eNB 310, device 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'. The UE506 may correspond to the UE 104, 350, 1150, 1350, 1550, 1750, 1950, 2350. In addition, the base station 504 and the UE506 may be configured to communicate using narrowband communications 509 (e.g., NB-IoT and/or eMTC). For example, the UE506 may be an NB-IoT device and/or an eMTC device. In fig. 5B-5D, optional operations are indicated by dashed lines.

Referring to fig. 5B, the base station 504 may operate 513 in an in-band mode, a guard band mode, or a standalone mode. In certain aspects, the base station 504 may determine 515 a narrowband TDD frame structure for narrowband communications 509 (see fig. 5D) from a set of narrowband TDD frame structures (e.g., the configurations listed in table 410 in fig. 4). In one aspect, each narrowband TDD frame structure of the set of narrowband TDD frame structures may include at least one common downlink subframe, as described below.

NPSS

In certain aspects, the base station 504 may determine 517 a common subframe for transmitting NPSS521 from a plurality of common subframes. For example, when the determined narrowband TDD frame structure is one of configurations 0, 1, 2, 3, 4, 5, 6, or m, NPSS521 may be transmitted on one of subframe 0 or subframe 5, since subframes 0 and 5 are common downlink subframes in each of configurations 0, 1, 2, 3, 4, 5, 6, and m. In another example, when the determined narrowband TDD frame structure is determined from a subset of the configurations listed in table 410 (e.g., one of configurations 1, 2, 3, 4, 5, or 6), NPSS521 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each of configurations 1, 2, 3, 4, 5, and 6. Additionally and/or alternatively, the subframe used to transmit NPSS521 may be a function of the determined narrowband TDD frame structure. In one example, the function may be that the first downlink subframe in the narrowband TDD frame structure may be used to transmit NPSS 512. In certain aspects, a period associated with an NPSS transmitted using a narrowband TDD frame structure (e.g., transmitted once every 20ms) may be shorter or longer than an NPSS transmitted using a narrowband FDD frame structure (e.g., transmitted once every 10 ms). For example, if the NPSS and NPBCH carriers are different, and the NPSS carrier cannot be power boosted as much as in FDD, a reduced periodicity of NPSS transmission (e.g., more frequent transmission of NPSS) may be useful. In such a scenario, the UE506 may use more NPSS averaging to achieve increased coverage. An increased periodicity of NPSS transmissions (e.g., less frequent transmissions of NPSS) may be useful so that transmissions of NPBCH, NPSS, NSSS, SIBs, etc. may be accommodated in the same carrier.

In certain other aspects, base station 504 may determine 519 a sequence (e.g., a zadofffchu sequence) associated with NPSS 521. In certain other aspects, the NPSS sequence 521 may be associated with at least one of a TDD mode or a determined narrowband TDD frame structure. In certain other aspects, NPSS521 may have the same set of sequences as an NPSS transmitted using a narrowband FDD frame structure. The FDD NPSS sequence may include a Zadoff Chu sequence of length 11 with root index 5, and may flip the sign of some symbols (symbols) in the same sequence to provide better timing properties. In certain other aspects, NPSS521 may have a different set of sequences than an NPSS transmitted using a narrowband FDD frame structure. In certain other aspects, NPSS521 may have a different Zadoff Chu sequence for initialization than the NPSS transmitted in the FDD frame structure. In certain other aspects, the NPSS521 transmitted using the determined narrowband TDD frame structure may have a different cover code than the NPSS transmitted using the narrowband FDD frame structure. While using different NPSS sequences for narrowband TDD may increase the complexity of processing at the UE, if the UE knows that certain frequency bands support only TDD or FDD, the UE506 may limit NPSS search to only one corresponding sequence in order to reduce this complexity.

NSSS

Referring to fig. 5C, base station 504 may transmit NSSS529 using the determined narrowband TDD frame structure. In an aspect, the periodicity of NSSS529 transmitted using the narrowband TDD frame structure may be the same as compared to the periodicity of NSSS transmitted using the narrowband FDD frame structure (NSSS is transmitted in subframe 9 of every other radio frame).

Alternatively, the period of NSSS529 transmitted using the narrowband TDD frame structure may be increased compared to the period of NSSS transmitted using the narrowband FDD frame structure (NSSS is transmitted in subframe 9 of every other radio frame). Thus, the period of NSSS529 transmitted using the narrowband TDD frame structure may be greater than two radio frames. If separate carriers are used for NPSS 521/NSSS 529 and NPBCH/SIB, it may be beneficial to increase the period over which NSSS529 is sent, since NSSS subframes may not otherwise be available. Furthermore, since there may not be an NRS on the NSSS carrier, additional NSSS measurements may be needed.

In certain aspects, NSSS529 may be transmitted using a different RB than the RB (e.g., carrier) used to transmit NPSS 521. In scenarios where the periodicity of NPSS521 is reduced (e.g., NPSS521 is not transmitted in each radio frame) or increased (e.g., NPSS521 is transmitted in each radio frame or NPSS521 is transmitted more than once in each radio frame), NSSS529 may be transmitted in radio frames that do not include NPSS 521. If we have separate carriers for PSS/SSS and PBCH/SIB, it may make sense to increase the associated periodicity, since the SSS subframe may not otherwise be available. Furthermore, since there is no more NRS on this carrier, more SSS for measurement may be needed.

Additionally and/or alternatively, NSSS529 and NPSS521 may be multiplexed such that one of NSSS529 or NPSS521 is transmitted in even numbered subframes and the other of NSSS529 or NPSS521 is transmitted in odd numbered subframes.

In certain aspects, the base station 504 may determine 517 a common subframe for transmitting NSSS529 from the plurality of common subframes described above. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NSSS529 may be sent on one of subframe 0 or subframe 5 because subframes 0 and 5 are common downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NSSS529 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each of configurations 1, 2, 3, 4, 5, and 6. In one example, NSSS may be transmitted on a special subframe, which may result in a different length of NSSS for a narrowband TDD configuration compared to a narrowband FDD configuration.

In an aspect, the base station 504 may determine 523 at least one of the following from the determined narrowband TDD frame structure: a period of NSSS529, a time location of NSSS529, or a frequency location of NSSS 529.

In certain aspects, the UE506 can distinguish between a narrowband FDD frame structure and a narrowband TDD frame structure when performing NSSS search 527. For example, when using a narrowband FDD frame structure, base station 504 may send NPSS521 in subframe 5 in odd-numbered radio frames and NSSS529 in subframe 9 in even-numbered radio frames. In certain other aspects, base station 504 may transmit NPSS521 in subframe 0 in odd-numbered radio frames and NSSS529 in subframe 5 in even-numbered radio frames. In certain other aspects, base station 504 may transmit NPSS521 in subframe 5 in even-numbered radio frames and NSSS529 in subframe 0 in odd-numbered radio frames. Based on the subframe number and even/odd number of radio frames used to transmit NPSS521 and NSSS529, UE506 can determine (e.g., implicitly determine without signaling from base station 504) whether base station 504 uses a narrowband FDD frame structure or a narrowband TDD frame structure. Additionally and/or alternatively, the UE506 can determine 531 a cell Identification (ID) and timing information based on the NSSS 529. For example, the UE506 may use NSSS to determine cell ID and radio frame boundary (e.g., 20ms frame boundary).

Referring to fig. 5C, the base station 504 may determine 525 a predetermined distance (e.g., a subframe distance and/or a radio frame boundary) between the NPSS521 and the NSSS529 and transmit information to the UE506 using the predetermined distance. For example, the predetermined distance may be configured to communicate information associated with at least one of: a TDD mode (e.g., an in-band mode, a guard band mode, and/or an independent mode) used by base station 504, an FDD mode, a determined narrowband TDD frame structure, a bandwidth associated with the TDD mode, or theta _ f or theta associated with the narrowband TDD frame structure and used to indicate NSSS529 sequences_fAnd (6) mapping. For narrowband communications using a narrowband FDD frame structure, θ_fThe mapping may be used to indicate the NSSS sequence. E.g. theta_fCan be defined asIn narrowband communications using a narrowband TDD frame structure, θ_fThe mapping may be relative to θ for narrowband FDD frame structures_fThe mapping is the same except for n_fIs different. NPSS52The distance between 1 and NSSS529 can be used to transmit n_fWhere the UE506 may use n_fTo use the value of theta_fMapping determines the NSSS sequence.

NPBCH

Referring to fig. 5D, when the base station 504 is operating in a in-band mode, the base station 504 can determine 533 in which of the common subframes described above the NPBCH535 is transmitted. In an aspect, the base station 504 may transmit the NPBCH535 in a different narrowband carrier than the narrowband carrier used to transmit the NPSS521 and/or NSSS 529.

For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, the NPBCH535 may be transmitted on one of subframe 0 or subframe 5 because subframes 0 and 5 are common downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, the NPBCH535 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Alternatively, the base station 504 may transmit the NPBCH535 in a radio frame that does not include NSSS529 (e.g., to accommodate NSSS 529).

In certain aspects, the period of NPBCH transmission using a narrowband TDD frame structure may be reduced compared to the period of NPBCH transmission using a narrowband FDD frame structure.

In some scenarios, prior to the NPBCH decoding process, the UE506 may not know whether the base station 504 is using a narrowband FDD frame structure or a narrowband TDD frame structure. In such a scenario, the UE506 may assume whether the base station 504 is using a narrowband FDD frame structure or a narrowband TDD frame structure during the NPBCH decoding process. To avoid a scenario where the UE506 assumes the type of frame structure, the base station 504 may include information in the NPBCH535 indicating to the UE506 that a narrowband TDD frame structure is being used. For example, the base station 504 can include a Cyclic Redundancy Check (CRC) mask in the NPBCH535 to indicate that a narrowband TDD frame structure is being used. Additionally and/or alternatively, the CRC mask in the NPBCH535 may indicate to the UE506 which configuration the narrowband TDD frame structure uses (e.g., see table 410 in fig. 4). Further, the inclusion of the CRC mask may prevent legacy UEs (e.g., UEs that are not configured for narrowband communications using the TDD frame structure) from attempting to decode the NPBCH 535.

In certain other aspects, the periodicity of the NPBCH535 transmitted by the base station 504, the time location of the NPBCH535, or the frequency location of the NPBCH535 may be related to the determined narrowband TDD frame structure.

Additionally, the NPBCH535 may include: a first bit that may indicate to the UE506 whether a narrowband TDD frame structure is being used; a second bit, which may indicate to the UE506 whether a narrowband FDD frame structure is being used; information indicating the RB location or subframe location associated with the SIB 537 transmitted by the base station 504; or information used to decode SIB 537. In another aspect, the NPBCH535 may comprise a single bit that may indicate to the UE506 whether a narrowband TDD frame structure or a narrowband FDD frame structure is being used.

SIB

In certain aspects, the base station 504 may transmit the SIB 537 (e.g., SIB-1) using the same RBs and/or a different RB than used to transmit one or more of the NPSS521, NSSS529, and/or NPBCH 535. The UE506 may use the bandwidth for the narrowband communication 509, the deployment type (e.g., in-band mode, guard-band mode, standalone mode), and/or the frequency location associated with the NPBCH535 to derive which RB to use to carry the SIB 537.

In certain aspects, the base station 504 may transmit the SIB 537 using one of the common subframes described above. For example, when the narrowband TDD frame structure is one of configurations 0, 1, 2, 3, 4, 5, 6, and m, SIB 537 may be sent on one of subframe 0 or subframe 5 because subframes 0 and 5 are common downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, SIB 537 may be sent on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each of configurations 1, 2, 3, 4, 5, and 6. Alternatively, the base station 504 can transmit the SIB 537 in a downlink subframe that is a function of the determined narrowband TDD frame structure (e.g., transmit the SIB 537 in the first downlink subframe).

NRS

In certain aspects, base station 504 may transmit Narrowband Reference Signal (NRS)541 using a narrowband TDD frame structure determined for narrowband communication 509. For example, the base station 504 can transmit NRSs using subframes that are also used to transmit SIBs 537 and/or NPBCH 535. Additionally, NRS 541 may be transmitted using a different narrowband carrier than the narrowband carrier used to transmit NPSS521 and/or NSSS 529.

In certain other aspects, base station 504 may transmit NRS 541 using one of the common subframes described above. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NRS 541 may be transmitted on one of subframe 0 or subframe 5 because subframes 0 and 5 are common downlink subframes in each configuration in the group. Further, NRS 541 may be transmitted on subframe 1 or subframe 6 because subframes 1 and 6 are special subframes (e.g., which include downlink resources) or downlink subframes in each of configurations 0, 1, 2, 3, 4, 5, 6, and m. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NRS 541 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Alternatively, base station 504 may transmit NRS 541 in a downlink subframe that is not a function of the determined narrowband TDD frame structure. For example, NPBCH535 (e.g., broadcast signaling) transmitted by base station 504 may be used to indicate to UE506 the downlink subframe that includes NRS 541 when the downlink subframe used to transmit NRS 541 is not a function of the determined narrowband TDD frame structure. In certain aspects, a bitmap 539 may be included in the NPBCH 535.

In an aspect, NRS 541 may be transmitted in the DwPTS portion of the special subframe (e.g., see fig. 4) and the downlink subframe in the determined narrowband TDD frame structure. In an aspect, the same symbol in the DwPTS portion of the special subframe and the downlink subframe may be used for transmitting NRS 541. When the NRS 541 is transmitted in the DwPTS of the special subframe, the UpPTS portion of the special subframe may be punctured.

In certain aspects, the NRS 541 transmitted using the narrowband TDD frame structure may be more dense than the NRS transmitted using the narrowband FDD frame structure. In other words, NRS 541 occupancy (e.g., density) in the time-frequency grid in the narrowband TDD frame structure may be greater than in the narrowband FDD frame structure. Thus, a higher pilot density may be used in the narrowband TDD frame structure, since the narrowband TDD frame structure may have a reduced number of downlink subframes for averaging channel variations and/or noise variations, unlike the narrowband FDD frame structure. In certain other aspects, NRS 541 may be transmitted in the same subframe as used by base station 504 to transmit CRS.

Fig. 6 is a flow chart 600 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'). In fig. 6, optional operations are indicated by dashed lines.

For example, referring to fig. 5A, the base station 504 may operate 501 in a standalone mode and the bandwidth associated with the standalone mode (e.g., the bandwidth the base station 504 determines to use for narrowband communications 509) may be different from the bandwidth available for L TE communications.

The method may include the steps of determining a narrowband TDD frame structure for narrowband communications at 604, the narrowband TDD frame structure may include two or more consecutive downlink subframes or one or more flexible subframes, wherein a flexible subframe may be configured as a downlink subframe or an uplink subframe, in some other configurations, when a UE uses a first duration to switch between monitoring a downlink subframe and transmitting a transmission using an uplink subframe, a special subframe may be located in two half-frames of the narrowband TDD frame structure, in some other configurations, when a UE uses a second duration longer than the first duration to switch between monitoring a downlink subframe and transmitting a transmission using an uplink subframe, a special subframe may be located in a first half-frame of the narrowband TDD frame structure, but not in a second half-frame of the narrowband TDD frame structure, in some other configurations, when a UE uses a third duration longer than the second duration to switch between monitoring a downlink subframe and transmitting a transmission using an uplink subframe, e.g. a narrow-band subframe, e.g. a subframe, a special subframe may be located in a narrowband subframe, e.g. a narrowband subframe, a special subframe may be a subframe, e.g. a subframe, a subframe may be a subframe, a special subframe may be configured as a subframe, a subframe may be configured in a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a subframe, a.

At 606, the base station may transmit the SIB in a first subframe of the narrowband TDD frame structure. For example, referring to fig. 5A, if one of configurations 4, 5, m, or n (e.g., a configuration with or configurable with four downlink subframes) is determined to be used as a narrowband TDD frame structure, SIB507 may also be transmitted in a different subframe than the subframe used to transmit NSSS 505, as discussed above with respect to fig. 5B-5D. For example, assuming that the base station 504 determines that the narrowband TDD frame structure includes configuration 5, the base station 504 may send NSSS 505 in subframe 5 and SIB507 in subframe 7 (or vice versa).

At 608, the base station may transmit the SSS in a second subframe of the narrowband TDD frame structure. In an aspect, the second subframe may be different from the first subframe. For example, referring to fig. 5A, if one of configurations 4, 5, m, or n (e.g., a configuration with or configurable with four downlink subframes) is determined to be used as a narrowband TDD frame structure, SIB507 may also be sent in a different subframe than the subframe used to send NSSS 505, as discussed above with reference to fig. 5B-5D. For example, assuming that the base station 504 determines that the narrowband TDD frame structure includes configuration 5, the base station 504 may send NSSS 505 in subframe 5 and SIB507 in subframe 7 (or vice versa).

At 610, the base station may communicate with the UE using the narrowband TDD frame structure determined for narrowband communication. For example, referring to fig. 5A, the base station 504 and the UE506 may be configured to communicate using narrowband communications 509 (e.g., NB-IoT and/or eMTC).

Fig. 7 is a flow chart 700 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'). In fig. 7, optional operations are indicated by dashed lines.

At 702, a base station may determine a TDD mode for narrowband communication. For example, referring to fig. 5B-5D, the base station 504 may operate 513 in an in-band mode, a guard-band mode, or a standalone mode.

At 704, the base station may determine a TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure in the set of narrowband TDD frame structures may be configured as a downlink subframe. In another aspect, a first periodicity associated with a PSS using a narrowband TDD frame structure may be increased compared to a second periodicity associated with a transmission of a second PSS using a narrowband FDD frame structure. For example, referring to fig. 5B-5D, base station 504 may determine 515 a narrowband TDD frame structure for narrowband communication 509 from a set of narrowband TDD frame structures (e.g., the configurations listed in table 410 in fig. 4). In one aspect, each narrowband TDD frame structure of the set of narrowband TDD frame structures may include at least one common downlink subframe. Base station 504 may determine which of the common subframes to use to transmit NPSS 521. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NPSS521 may be transmitted on one of subframe 0 or subframe 5, since subframes 0 and 5 are common downlink subframes in each of configurations 0, 1, 2, 3, 4, 5, 6, and m. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NPSS521 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Additionally and/or alternatively, the subframe used to transmit NPSS521 may be a function of the determined narrowband TDD frame structure. In one example, the function may be that the first downlink subframe in the narrowband TDD frame structure may be used to transmit NPSS 512. In certain aspects, a periodicity associated with NPSS transmissions in a narrowband TDD frame structure (e.g., sent once every 20ms) may be reduced compared to NPSS transmissions in a narrowband FDD frame structure.

At 706, the base station may determine one of the plurality of common subframes for transmitting the PSS. In an aspect, one of the plurality of common subframes may be determined according to a narrowband TDD frame structure selected for narrowband communication. For example, referring to fig. 5B-5D, base station 504 may determine 515 which of the common subframes is used to transmit NPSS 521. In certain aspects, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NPSS521 may be sent on one of subframe 0 or subframe 5, since subframes 0 and 5 are common downlink subframes in each configuration in the group. In certain other aspects, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NPSS521 may be transmitted on one of subframe 0, subframe 5, or subframe 9, since subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Additionally and/or alternatively, the subframe used to transmit NPSS521 may be a function of the determined narrowband TDD frame structure. In one example, the function may be that the first downlink subframe in the narrowband TDD frame structure may be used to transmit NPSS 512. In certain other aspects, a periodicity associated with NPSS transmissions in a narrowband TDD frame structure (e.g., sent once every 20ms) may be reduced as compared to NPSS transmissions in a narrowband FDD frame structure.

At 708, the base station may transmit the PSS using at least one common subframe in a narrowband TDD frame structure determined for narrowband communication. In an aspect, a first periodicity associated with transmitting the PSS using a narrowband TDD frame structure may be reduced or increased compared to a second periodicity associated with transmission of a second PSS using a narrowband FDD frame structure. For example, referring to fig. 5B-5D, base station 504 may determine 515 which of the common subframes is used to transmit NPSS 521. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NPSS521 may be sent on one of subframe 0 or subframe 5, since subframes 0 and 5 are common downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NPSS521 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Additionally and/or alternatively, the subframe used to transmit NPSS521 may be a function of the determined narrowband TDD frame structure. In one example, the function may be that the first downlink subframe in the narrowband TDD frame structure may be used to transmit NPSS 512. In certain aspects, a periodicity associated with NPSS transmissions in a narrowband TDD frame structure (e.g., sent once every 20ms) may be reduced compared to NPSS transmissions in a narrowband FDD frame structure. In certain aspects, a periodicity associated with NPSS transmissions in a narrowband TDD frame structure (e.g., sent once every 20ms) may be reduced compared to NPSS transmissions in a narrowband FDD frame structure.

Fig. 8 is a flow chart 800 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302').

At 802, a base station can determine a TDD mode for narrowband communications. For example, referring to fig. 5B-5D, the base station 504 may operate 513 in an in-band mode, a guard-band mode, or a standalone mode.

At 804, the base station may determine a narrowband TDD frame structure for narrowband communications from a set of narrowband TDD frame structures. For example, referring to fig. 5B-5D, base station 504 may determine 515 a narrowband TDD frame structure for narrowband communication 509 from a set of narrowband TDD frame structures (e.g., the configurations listed in table 410 in fig. 4). In one aspect, each narrowband TDD frame structure of the set of narrowband TDD frame structures may include at least one common downlink subframe. Base station 504 may determine 515 which of the common subframes to use to transmit NPSS 521. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NPSS521 may be sent on one of subframe 0 or subframe 5, since subframes 0 and 5 are common downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NPSS521 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Additionally and/or alternatively, the subframe used to transmit NPSS521 may be a function of the determined narrowband TDD frame structure. In one example, the function may be that the first downlink subframe in the narrowband TDD frame structure may be used to transmit NPSS 512.

At 806, the base station may transmit the PSS using a narrowband TDD frame structure selected for narrowband communication. In an aspect, the set of PSS sequences may be associated with at least one of the TDD mode or the determined narrowband TDD frame structure. In another aspect, the set of PSS sequences transmitted using the narrowband TDD frame structure may be the same as the second set of PSS sequences transmitted using the narrowband FDD frame structure. In further aspects, the set of PSS sequences transmitted using the narrowband TDD frame structure may be different from the second set of PSS sequences transmitted using the narrowband FDD frame structure. In certain other aspects, the set of PSS sequences transmitted using the narrowband TDD frame structure may have a different Zadoff Chu sequence for initialization than the second set of PSS sequences transmitted using the narrowband FDD frame structure. In certain other aspects, the set of PSS sequences transmitted using the narrowband TDD frame structure may have a different cover code than the second set of PSS sequences transmitted using the narrowband FDD frame structure. For example, referring to fig. 5B-5D, base station 504 may determine 519 a sequence associated with NPSS 521. In an aspect, the sequence of NPSS521 may be associated with at least one of a TDD mode or a determined narrowband TDD frame structure. In certain aspects, the NPSS521 transmitted using the determined narrowband TDD frame structure may have the same sequence as the NPSS transmitted using the narrowband FDD frame structure. In certain other aspects, the NPSS521 transmitted using the determined narrowband TDD frame structure may have a different sequence than the NPSS transmitted using the narrowband FDD frame structure. In certain other aspects, the NPSS521 transmitted using the determined narrowband TDD frame structure may have a different Zadoff Chu sequence for initialization than the NPSS transmitted in the FDD frame structure. In certain other aspects, the NPSS521 transmitted using the determined narrowband TDD frame structure may have a different cover code than the NPSS transmitted using the narrowband FDD frame structure.

Fig. 9 is a flow chart 900 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'). In fig. 9, optional operations are indicated by dashed lines.

At 902, a base station can determine a narrowband communication frame structure including FDD mode or TDD mode and determine a particular TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure in the set of narrowband TDD frame structures may be configured as a downlink subframe. In another aspect, the SSS may be transmitted using at least one common subframe in a narrowband TDD frame structure determined for narrowband communication. In a further aspect, the set of narrowband TDD frame structures may include a subset of all narrowband TDD frame structures available for narrowband communication. For example, referring to fig. 5B-5D, base station 504 may determine 515 a narrowband TDD frame structure for narrowband communication 509 from a set of narrowband TDD frame structures (e.g., the configurations listed in table 410 in fig. 4). When the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NSSS529 may be sent on one of subframe 0 or subframe 5, since subframes 0 and 5 are common downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NSSS529 may be sent on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group.

At 904, the base station may determine an SSS sequence and a predetermined distance between transmitting the PSS and the SSS. In an aspect, at least one of the SSS sequence or the predetermined distance may be configured to transmit information associated with the narrowband communication to the UE. In another aspect, the information may include at least one of: TDD mode, FDD mode, narrowband TDD frame structure determined for narrowband communications, bandwidth associated with TDD mode, or frequency offset of a first carrier used to transmit a Physical Broadcast Channel (PBCH) or System Information Block (SIB) relative to a second carrier used to transmit one or more of SSS or PSS. For example, referring to fig. 5B-5D, base station 504 may determine a predetermined distance (e.g., a subframe distance) between NPSS521 and NSSS529, and use the predetermined distance to transmit information to UE 506. For example, the predetermined distance may be configured to communicate information associated with at least one of: TDD mode (e.g., in-band mode, guard band mode, and/or standalone mode) used by base station 504,FDD mode, determined narrowband TDD frame structure, bandwidth associated with TDD mode, or θ associated with narrowband TDD frame structure and indicating NSSS529 sequence_fAnd (6) mapping. Theta for indicating NSSS sequence for narrowband communication using narrowband FDD frame structure_fThe mapping may be defined asIn narrowband communications using a narrowband TDD frame structure, θ_fThe mapping may be relative to θ for narrowband FDD frame structures_fThe mapping is the same except for n_fIs different. The distance between NPSS521 and NSSS529 can be used to transmit n_fWhere the UE506 may use n_fTo use the value of theta_fMapping determines the NSSS sequence.

At 906, the base station may determine a periodicity, a subframe number, and a transmission sequence associated with the SSS based at least in part on the narrowband TDD frame structure. For example, referring to fig. 5B-5D, NSSS529 may be transmitted using a different RB than the RB (e.g., carrier) used to transmit NPSS 521. In a configuration where the period of NPSS521 is reduced (e.g., NPSS521 is not transmitted in every radio frame), NSSS529 may be transmitted in radio frames that do not include NPSS 521. In one aspect, NSSS529 may be transmitted in the same subframe number used to transmit NPSS521, but in a radio frame that does not include NPSS 521. For example, assuming NPSS521 is transmitted in subframe 5 in even-numbered radio frames, NSSS529 may be transmitted in subframe 5 in odd-numbered radio frames. Alternatively, base station 504 may transmit NPSS521 in subframe 0 in odd-numbered radio frames and NSSS529 in subframe 5 in even-numbered radio frames. In another configuration, base station 504 may transmit NPSS521 in subframe 5 in even-numbered radio frames and NSSS529 in subframe 0 in odd-numbered radio frames.

At 908, the base station may transmit the PSS using the narrowband TDD frame structure determined for narrowband communication. In an aspect, the PSS may be transmitted on a different narrowband carrier than the SSS. In another aspect, the PSS may be transmitted using a specific subframe. In further aspects, the PSS may not be transmitted in every frame. In a further aspect, the SSS may be transmitted using a specific subframe in at least one frame in which the PSS is not transmitted. In yet another aspect, the PSS may be transmitted using a specific subframe. In further aspects, the SSS may be transmitted using subframes other than the specific subframes. For example, referring to fig. 5B-5D, NSSS529 may be transmitted using a different RB than the RB (e.g., carrier) used to transmit NPSS 521. In a configuration where the period of NPSS521 is reduced (e.g., NPSS521 is not transmitted in every radio frame), NSSS529 may be transmitted in radio frames that do not include NPSS 521. In one aspect, NSSS529 may be transmitted in the same subframe number used to transmit NPSS521, but in a radio frame that does not include NPSS 521. For example, assuming NPSS521 is transmitted in subframe 5 in even-numbered radio frames, NSSS529 may be transmitted in subframe 5 in odd-numbered radio frames. Alternatively, base station 504 may transmit NPSS521 in subframe 0 in odd-numbered radio frames and NSSS529 in subframe 5 in even-numbered radio frames. In another configuration, base station 504 may transmit NPSS521 in subframe 5 in even-numbered radio frames and NSSS529 in subframe 0 in odd-numbered radio frames.

At 910, the base station may transmit the SSS using a narrowband TDD frame structure determined for narrowband communication. In an aspect, the SSS may be transmitted using the same subframe in at most every other frame. In another aspect, a period associated with transmitting the SSS using the narrowband TDD frame structure may be increased or decreased as compared to a period associated with transmission of the second SSS using the narrowband FDD frame structure. In a further aspect, at least one of a periodicity associated with transmitting the SSS, a time location associated with transmitting the SSS, or a frequency location associated with transmitting the SSS is related to a narrowband TDD frame structure determined for narrowband communications. For example, referring to fig. 5B-5D, base station 504 may transmit NSSS529 using the determined narrowband TDD frame structure. In an aspect, NSSS529 may be transmitted using the same subframe in every other radio frame. In other words, the period of NSSS529 transmitted using the narrowband TDD frame structure may be reduced compared to the period of NSSS transmitted using the narrowband FDD frame structure. The base station 504 may determine 523 at least one of the following from the determined narrowband TDD frame structure: a period of NSSS529, a time location of NSSS529, or a frequency location of NSSS 529.

Fig. 10 is a flow chart 1000 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302').

At 1002, a base station can determine a narrowband communication frame structure comprising an FDD frame structure or a TDD frame structure and determine a narrowband TDD frame structure configuration for narrowband communication from a set of narrowband TDD frame structure configurations. For example, referring to fig. 5B-5D, base station 504 may determine 515 from a set of narrowband TDD frame structures (e.g., the configurations listed in table 410 in fig. 4) whether to use an FDD frame structure or a TDD frame structure that includes a narrowband TDD frame structure configuration for narrowband communication 509.

At 1004, the base station may determine one or more narrowband carriers and subframes within the one or more narrowband carriers based on a narrowband communication frame structure or TDD frame structure configuration to transmit at least one of a BCH or a SIB 1. For example, referring to fig. 5B-5D, the base station 504 can determine one or more narrowband carriers and subframes within the one or more narrowband carriers to transmit a SIB (e.g., SIB1) and/or BCH. The base station 504 may transmit the SIB 537 using the same RB (e.g., carrier) or a different RB as used to transmit one or more of the NPSS521, NSSS529, and/or NPBCH 535. The UE506 may use the bandwidth for the narrowband communication 509, the deployment type (e.g., in-band mode, guard-band mode, standalone mode), and/or the frequency location associated with the NPBCH535 to derive which RB to use for sending the SIB 537 to the UE 506.

At 1006, the base station may transmit the PSS, SSS, and at least one of BCH or SIB1 using the narrowband TDD frame structure determined for narrowband communication. In an aspect, the carrier used to transmit the BCH and/or SIB may be different from the carrier used to transmit one or more of the PSS or SSS. In another aspect, the narrowband carrier used to transmit the BCH may be different from the narrowband carrier used to transmit one or more of the PSS or SSS. In another aspect, the BCH may be transmitted using one or more subframes in each radio frame. In certain other aspects, the SSS may be transmitted using a particular subframe in every other frame. In certain other aspects, the BCH may be transmitted using a particular subframe in each frame in which the SSS is not transmitted. In certain other aspects, a periodicity associated with transmitting the BCH may be used to indicate whether an FDD frame structure or a TDD frame structure is being used for narrowband communication. In certain other aspects, at least one of a periodicity associated with transmitting the BCH, a time location associated with transmitting the BCH, or a frequency location associated with transmitting the BCH can be related to one or more of: a narrowband TDD frame structure determined for narrowband communications, a second carrier containing a PSS or SSS, or information transmitted over a PSS or SSS. In certain other aspects, the first carrier used to transmit the BCH may be located at a fixed frequency offset with respect to the second carrier used to transmit one or more of the PSS or SSS. In certain other aspects, the BCH includes information indicative of at least one of: a narrowband TDD frame structure configuration determined for narrowband communication, whether the narrowband communication usage uses an FDD frame structure or a TDD frame structure, or a carrier location or subframe location associated with SIB 1. In certain other aspects, the information may be included in the BCH by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits. In certain other aspects, the first carrier may be used to transmit both BCH and SIB1 when the first carrier is different from the second carrier used to transmit PSS and SSS. In certain other aspects, the SIB1 may be transmitted using a different carrier than the first carrier used to transmit the BCH. In certain other aspects, at least one of the narrowband carrier location relative to the PSS carrier location or the subframe used to transmit the SIB1 may be associated with a narrowband frame structure determined for narrowband communication. For example, referring to fig. 5B-5D, the base station 504 can transmit the NPBCH535 using the determined narrowband TDD frame structure. In an aspect, the base station 504 may transmit the NPBCH535 in a different RB than the RBs used to transmit the NPSS521 and/or NSSS 529. Prior to the NPBCH decoding process, the UE506 may not know whether the base station 504 is using a narrowband FDD frame structure or a narrowband TDD frame structure. In such a scenario, the UE506 may assume whether the base station 504 is using a narrowband FDD frame structure or a narrowband TDD frame structure during the NPBCH decoding process. To avoid a scenario where the UE506 assumes the type of frame structure, the base station 504 may include information in the NPBCH535 indicating to the UE506 that a narrowband TDD frame structure is being used. For example, base station 504 can include a CRC mask in NPBCH535 indicating that a narrowband TDD frame structure is being used. Additionally, the inclusion of the CRC mask may prevent legacy UEs (e.g., UEs that are not configured for narrowband communications using the TDD frame structure) from attempting to decode the NPBCH 535. In certain aspects, the periodicity of the NPBCH535 transmitted by the base station 504, the time location of the NPBCH535, or the frequency location of the NPBCH535 may be related to the determined narrowband TDD frame structure. Additionally, the NPBCH535 may include: a first bit that may indicate to the UE506 whether a narrowband TDD frame structure is being used; a second bit, which may indicate to the UE506 whether a narrowband FDD frame structure is being used; information indicating the RB location or subframe location associated with the SIB 537 transmitted by the base station 504; or information used to decode SIB 537.

Fig. 11 is a conceptual data flow diagram 1100 illustrating the data flow between different units/components in an exemplary apparatus 1102. The apparatus may be a base station (e.g., base station 102, 180, 310, 504, apparatus 1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302') in narrowband communication (e.g., NB-IoT communication or eMTC) with a UE 1150 (e.g., UE 104, 350, 506, 1350, 1550, 1750, 1950, 2350). The apparatus may include a receiving component 1104, a determining component 1106, and a transmitting component 1108.

In one aspect, a narrowband TDD frame structure may be different from a L TETDD frame structure that may be used for L TE communications.

The transmitting component 1108 may be configured to transmit the SIB1103 to the UE 1150 in a first subframe of the narrowband TDD frame structure. The transmitting component 1108 may be configured to transmit the SSS 1103 in a second subframe of the narrowband TDD frame structure. In an aspect, the second subframe may be different from the first subframe. The transmitting component 1108 may be configured to transmit information associated with one or more of the following to the UE 1150: information 1103 associated with a bandwidth for narrowband communications and/or information 1103 associated with a narrowband TDD frame structure for narrowband communications.

The receiving component 1104 and/or the transmitting component 1108 may be configured to communicate 1103, 1105 with the UE 1150 using a narrowband TDD frame structure determined for narrowband communication. For example, receiving component 1104 may be configured to receive narrowband uplink transmission 1105 from UE 1150. The transmitting component 1108 may be configured to transmit one or more narrowband downlink transmissions 1103 to the UE 1150.

The apparatus may include additional components to perform each of the blocks of the algorithm in the flow chart of fig. 6 described above. As such, each block in the flow diagram of fig. 6 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process/algorithm, implemented by a processor configured to perform the process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 12 is a diagram 1200 illustrating an example of a hardware implementation of an apparatus 1102' employing a processing system 1214. The processing system 1214 may be implemented with a bus architecture, represented generally by the bus 1224. The bus 1224 may include any number of interconnected buses and bridges depending on the specific application of the processing system 1214 and the overall design constraints. The bus 1224 links together various circuits including one or more processors and/or hardware components (represented by the processor 1204), the components 1104, 1106, 1108, and the computer-readable medium/memory 1206. The bus 1224 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1214 may be coupled to a transceiver 1210. The transceiver 1210 is coupled to one or more antennas 1220. The transceiver 1210 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1210 receives a signal from the one or more antennas 1220, extracts information from the received signal, and provides the extracted information to the processing system 1214, and in particular the receive component 1104. Additionally, the transceiver 1210 receives information from the processing system 1214 (and in particular the transmitting component 1108) and generates a signal based on the received information that is to be applied to the one or more antennas 1220. The processing system 1214 includes a processor 1204 coupled to a computer-readable medium/memory 1206. The processor 1204 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1206. The software, when executed by the processor 1204, causes the processing system 1214 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1206 may also be used for storing data that is manipulated by the processor 1204 when executing software. The processing system 1214 also includes at least one of the components 1104, 1106, 1108. The components may be software components running in the processor 1204, resident/stored in the computer readable medium/memory 1206, one or more hardware components coupled to the processor 1204, or some combination thereof. The processing system 1214 may be a component of the eNB 310 and may include at least one of the TX processor 316, the RX processor 370, and the controller/processor 375, and/or the memory 376.

In some aspects, apparatus 1102/1102 'for wireless communications may include means for determining a bandwidth for narrowband communications in one aspect, the bandwidth for narrowband communications may be different from a bandwidth available for L TE communications in some other aspects, apparatus 1102/1102' for wireless communications may include means for determining a narrowband TDD frame structure for narrowband communications in one aspect, the narrowband TDD frame structure may be different from a L TE TDD frame structure available for L TE communications in another aspect, a switching period from a downlink subframe to an uplink subframe in the narrowband TDD frame structure may be longer than a switching period in an L TE TDD frame structure in another aspect, the narrowband TDD frame structure has at least three consecutive downlink subframes in some other aspects, apparatus 1102/1102 'for wireless communications may include means for transmitting a SIB in a first subframe of the narrowband TDD frame structure in some other aspects, apparatus 1102/1102' for wireless communications may include means for processing a second narrowband subframe of the narrowband frame structure 375, means for processing a TX subframe, and/processing means for TX 316, a TX processing means for processing a TX 316, a TX processing means for processing means 375, a TX processing means for processing, a TX 316, a TX processing means, a transceiver, and a transceiver, and a processor, a transceiver.

Fig. 13 is a conceptual data flow diagram 1300 illustrating the data flow between different units/components in an exemplary apparatus 1302. The apparatus may be a base station (e.g., base station 102, 180, 310, 504, apparatus 1102/1102 ', 1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302') in narrowband communication (e.g., NB-IoT communication or eMTC) with a UE 1350 (e.g., UE 104, 350, 506, 1150, 1550, 1750, 1950, 2350). The apparatus may include a receiving component 1304, a determining component 1306, and a transmitting component 1308.

The determining component 1306 may be configured to determine a TDD mode for narrowband communications. The determining component 1306 may be configured to determine a TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure in the set of narrowband TDD frame structures may be configured as a downlink subframe. In another aspect, a first periodicity associated with a PSS using a narrowband TDD frame structure may be increased compared to a second periodicity associated with a transmission of a second PSS using a narrowband FDD frame structure. The determining component 1306 may be configured to determine one of the plurality of common subframes for transmitting the PSS. In an aspect, one of the plurality of common subframes may be determined according to a narrowband TDD frame structure selected for narrowband communication. The determining component 1306 may be configured to transmit a signal 1301 to the transmitting component 1308, the signal 1301 comprising information associated with one or more of: a TDD mode for narrowband communication, a TDD frame structure for narrowband communication, and/or one of a plurality of common subframes.

The transmitting component 1308 may be configured to transmit information 1303 associated with one or more of the following to the UE 1350: a TDD mode for narrowband communication, a TDD frame structure for narrowband communication, and/or one of a plurality of common subframes. The transmitting component 1308 can be configured to transmit the PSS 1303 (e.g., NPSS) using at least one common subframe in a narrowband TDD frame structure determined for narrowband communication. In an aspect, a first periodicity associated with transmitting the PSS 1303 using a narrowband TDD frame structure may be increased compared to a second periodicity associated with transmission of the second PSS 1303 using a narrowband FDD frame structure.

The receiving component 1304 and/or the transmitting component 1308 may be configured to communicate 1303, 1305 with the UE 1350 using a narrowband TDD frame structure determined for narrowband communication. For example, the receiving component 1304 may be configured to receive a narrowband uplink transmission 1305 from the UE 1350. The transmitting component 1308 can be configured to transmit one or more narrowband downlink transmissions 1303 to the UE 1350.

The apparatus may include additional components to perform each of the blocks of the algorithm in the flow chart of fig. 7 described above. As such, each block in the flow diagram of fig. 7 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process/algorithm, implemented by a processor configured to perform the process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 14 is a diagram 1400 illustrating an example of a hardware implementation of an apparatus 1302' employing a processing system 1414. The processing system 1414 may be implemented with a bus architecture, represented generally by the bus 1424. The bus 1424 may include any number of interconnected buses and bridges depending on the specific application of the processing system 1414 and the overall design constraints. The bus 1424 links together various circuits including one or more processors and/or hardware components (represented by the processor 1404), components 1304, 1306, 1308, and the computer-readable medium/memory 1406. The bus 1424 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1414 can be coupled to the transceiver 1410. The transceiver 1410 is coupled to one or more antennas 1420. The transceiver 1410 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1410 receives signals from the one or more antennas 1420, extracts information from the received signals, and provides the extracted information to the processing system 1414, and in particular the receive component 1304. Additionally, transceiver 1410 receives information from processing system 1414, and in particular, transmitting component 1308, and generates a signal to be applied to one or more antennas 1420 based on the received information. The processing system 1414 includes a processor 1404 coupled to a computer-readable medium/memory 1406. The processor 1404 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1406. The software, when executed by the processor 1404, causes the processing system 1414 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1406 may also be used for storing data that is manipulated by the processor 1404 when executing software. The processing system 1414 also includes at least one of the components 1304, 1306, 1308. The components may be software components running in the processor 1404, resident/stored in the computer readable medium/memory 1406, one or more hardware components coupled to the processor 1404, or some combination thereof. The processing system 1414 may be a component of the base station 310 and may include at least one of the TX processor 316, the RX processor 370, and the controller/processor 375, and/or the memory 376.

In certain aspects, the means 1302/1302' for wireless communication may comprise: means for determining a TDD mode for narrowband communication. In certain other aspects, the means for wireless communicating 1302/1302' may comprise: means for determining a TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure in the set of narrowband TDD frame structures may be configured as a downlink subframe. In another aspect, a first periodicity associated with a PSS using a narrowband TDD frame structure may be increased compared to a second periodicity associated with a transmission of a second PSS using a narrowband FDD frame structure. In certain other aspects, the means for wireless communicating 1302/1302' may comprise: means for determining one common subframe of a plurality of common subframes for transmitting the PSS. In one configuration, one common subframe of the plurality of common subframes may be determined according to a narrowband TDD frame structure selected for narrowband communications. In certain other aspects, the means for wireless communicating 1302/1302' may comprise: means for transmitting the PSS using at least one common subframe in a narrowband TDD frame structure determined for narrowband communication. In an aspect, a first periodicity associated with transmitting the PSS using a narrowband TDD frame structure may be increased compared to a second periodicity associated with transmission of a second PSS using a narrowband FDD frame structure. The aforementioned means may be one or more of the aforementioned components of the apparatus 1302 and/or the processing system 1414 of the apparatus 1302' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1414 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

Fig. 15 is a conceptual data flow diagram 1500 illustrating the data flow between different units/components in an exemplary apparatus 1502. The apparatus may be a base station (e.g., base station 102, 180, 310, 504, apparatus 1102/1102 ', 1302/1302', 1502 ', 1702/1702', 1902/1902 ', 2302/2302') in narrowband communication (e.g., NB-IoT communication or eMTC) with a UE 1550 (e.g., UE 104, 350, 506, 1150, 1350, 1750, 1950, 2350). The apparatus can include a receiving component 1504, a determining component 1506, and a sending component 1508.

The determining component 1506 may be configured to determine a TDD mode for narrowband communications. The determining component 1506 may be configured to determine a narrowband TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. The determining component 1506 may be configured to send a signal 1501, the signal 1501 including information associated with one or more of: TDD mode for narrowband communications or narrowband TDD frame structure for narrowband communications.

Transmit component 1508 may be configured to transmit PSS 1503 using the narrowband TDD frame structure selected for narrowband communication. In an aspect, the sequence of PSS 1503 may be associated with at least one of the TDD mode or the determined narrowband TDD frame structure. In another aspect, the PSS sequence transmitted using the narrowband TDD frame structure may be the same as the second PSS sequence transmitted using the narrowband FDD frame structure. In further aspects, the PSS sequence transmitted using the narrowband TDD frame structure may be different from the second PSS sequence transmitted using the narrowband FDD frame structure. In certain other aspects, the PSS sequence transmitted using the narrowband TDD frame structure may have a different zadofffchu sequence for initialization than the second PSS sequence transmitted using the narrowband FDD frame structure. In certain other aspects, the PSS sequence transmitted using the narrowband TDD frame structure may have a different cover code than a second PSS sequence transmitted using the narrowband FDD frame structure. The sending component 1508 may be configured to send information 1503 associated with one or more of: TDD mode for narrowband communications or narrowband TDD frame structure for narrowband communications.

Receiving component 1504 and/or transmitting component 1508 may be configured to communicate 1503, 1505 with a UE 1550 using a narrowband TDD frame structure determined for narrowband communication. For example, receiving component 1504 may be configured to receive narrowband uplink transmission 1505 from UE 1550. Transmitting component 1508 may be configured to transmit one or more narrowband downlink transmissions 1503 to UE 1550.

The apparatus may include additional components to perform each of the blocks of the algorithm in the flow chart of fig. 8 described above. As such, each block in the flow diagram of fig. 8 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process/algorithm, implemented by a processor configured to perform the process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 16 is a diagram 1600 illustrating an example of a hardware implementation of an apparatus 1502' employing a processing system 1614. The processing system 1614 may be implemented with a bus architecture, represented generally by the bus 1624. The bus 1624 may include any number of interconnected buses and bridges depending on the specific application of the processing system 1614 and the overall design constraints. The bus 1624 links together various circuits including one or more processors and/or hardware components (represented by the processor 1604), the components 1504, 1506, 1508, and the computer-readable medium/memory 1606. The bus 1624 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1614 may be coupled to the transceiver 1610. The transceiver 1610 is coupled to one or more antennas 1620. The transceiver 1610 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1610 receives a signal from the one or more antennas 1620, extracts information from the received signal, and provides the extracted information to the processing system 1614, and in particular to the receiving component 1504. Additionally, the transceiver 1610 receives information from the processing system 1614 (and in particular the transmitting component 1508) and generates a signal to be applied to the one or more antennas 1620 based on the received information. The processing system 1614 includes a processor 1604 coupled to a computer-readable medium/memory 1606. The processor 1604 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1606. The software, when executed by the processor 1604, causes the processing system 1614 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1606 may also be used for storing data that is manipulated by the processor 1604 when executing software. The processing system 1614 also includes at least one of the components 1504, 1506, 1508. The components may be software components running in the processor 1604, resident/stored in the computer readable medium/memory 1606, one or more hardware components coupled to the processor 1604, or some combination thereof. The processing system 1614 may be a component of the base station 310 and may include the TX processor 316, the RX processor 370, and at least one of the controller/processor 375, and/or the memory 376.

In certain aspects, the means 1502/1502' for wireless communication may comprise: means for determining a TDD mode for narrowband communication. In certain other aspects, the means for wireless communicating 1502/1502' may comprise: means for determining a narrowband TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In certain other aspects, the means for wireless communicating 1502/1502' may comprise: means for transmitting the PSS using a narrowband TDD frame structure selected for narrowband communication. In an aspect, the PSS sequence may be associated with at least one of the TDD mode or the determined narrowband TDD frame structure. In another aspect, the PSS sequence transmitted using the narrowband TDD frame structure may be the same as the second PSS sequence transmitted using the narrowband FDD frame structure. In further aspects, the PSS sequence transmitted using the narrowband TDD frame structure may be different from the second PSS sequence transmitted using the narrowband FDD frame structure. In certain other aspects, the PSS sequence transmitted using the narrowband TDD frame structure may have a different Zadoff Chu sequence for initialization than the second PSS sequence transmitted using the narrowband FDD frame structure. In certain other aspects, the PSS sequence transmitted using the narrowband TDD frame structure may have a different cover code than a second PSS sequence transmitted using the narrowband FDD frame structure. The aforementioned means may be one or more of the aforementioned components of the apparatus 1502 and/or the processing system 1614 of the apparatus 1502' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1614 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

Fig. 17 is a conceptual data flow diagram 1700 illustrating the data flow between different means/components in an exemplary apparatus 1702. The apparatus may be a base station (e.g., base station 102, 180, 310, 504, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702', 1902/1902 ', 2302/2302') in narrowband communication (e.g., NB-IoT communication or eMTC) with a UE 1750 (e.g., UE 104, 350, 506, 1150, 1350, 1550, 1950, 2350). The apparatus can comprise a receiving component 1704, a determining component 1706, and a sending component 1708.

Determining component 1706 can be configured to determine a narrowband TDD frame structure for narrowband communications from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure in the set of narrowband TDD frame structures may be configured as a downlink subframe. In another aspect, the SSS may be transmitted using at least one common subframe in a narrowband TDD frame structure determined for narrowband communication. In a further aspect, the set of narrowband TDD frame structures may include a subset of all narrowband TDD frame structures available for narrowband communication. The determining component 1706 may be configured to determine a predetermined distance between transmitting the PSS and the SSS. In an aspect, the predetermined distance may be configured to communicate information associated with the narrowband communication to the UE. In another aspect, the information may include at least one of: TDD mode, FDD mode, narrowband TDD frame structure determined for narrowband communications, or bandwidth associated with TDD mode. The determining component 1706 may be configured to transmit a signal 1701 to the transmitting component 1708, the signal 1701 including information associated with at least one of: a narrowband TDD frame structure for narrowband communications and/or a predetermined distance between a transmit PSS and SSS.

Transmit component 1708 may be configured to transmit PSS 1703 using the narrowband TDD frame structure determined for narrowband communications. In an aspect, the PSS 1703 may be transmitted on a different resource block than the SSS. In another aspect, the PSS 1703 may be transmitted using a specific subframe. In further aspects, the PSS 1703 may not be transmitted in every frame. In further aspects, the SSS1703 may be transmitted using a specific subframe in at least one frame in which the PSS 1703 is not transmitted. In yet another aspect, the PSS 1703 may be transmitted using a particular subframe in every other subframe. In further aspects, the SSS1703 may be transmitted using subframes other than the specific subframes in each frame in which the PSS 1703 is not transmitted. Transmitting component 1708 may be configured to transmit SSS1703 using a narrowband TDD frame structure determined for narrowband communications. In an aspect, the SSS1703 may be transmitted using the same subframe in at most every other frame. In another aspect, the periodicity associated with transmitting the SSS1703 using a narrowband TDD frame structure may be reduced compared to the periodicity associated with transmission of the second SSS1703 using a narrowband FDD frame structure. In further aspects, at least one of a periodicity associated with transmitting the SSS1703, a time location associated with transmitting the SSS1703, or a frequency location associated with transmitting the SSS1703 is related to a narrowband TDD frame structure determined for narrowband communications.

Receiving component 1704 and/or transmitting component 1708 may be configured to communicate 1703, 1705 with UE 1750 using a narrowband TDD frame structure determined for narrowband communication. For example, receiving component 1704 may be configured to receive narrowband uplink transmission 1705 from UE 1750. Transmitting component 1708 may be configured to transmit one or more narrowband downlink transmissions 1703 to UE 1750.

The apparatus may include additional components to perform each of the blocks of the algorithm in the flow chart of fig. 9 described above. As such, each block in the flow diagram of fig. 9 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process/algorithm, implemented by a processor configured to perform the process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 18 is a diagram 1800 illustrating an example of a hardware implementation of an apparatus 1702' employing a processing system 1814. The processing system 1814 may be implemented with a bus architecture, represented generally by the bus 1824. The bus 1824 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 1814 and the overall design constraints. The bus 1824 links together various circuits including one or more processors and/or hardware components (represented by the processor 1804), the components 1704, 1706, 1708, and the computer-readable medium/memory 1806. The bus 1824 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 1814 may be coupled to a transceiver 1810. The transceiver 1810 is coupled to one or more antennas 1820. The transceiver 1810 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 1810 receives a signal from the one or more antennas 1820, extracts information from the received signal, and provides the extracted information to the processing system 1814 (and in particular the receive component 1704). Additionally, transceiver 1810 receives information from processing system 1814 (and in particular transmit component 1708) and generates a signal to be applied to one or more antennas 1820 based on the received information. The processing system 1814 includes a processor 1804 coupled to a computer-readable medium/memory 1806. The processor 1804 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 1806. The software, when executed by the processor 1804, causes the processing system 1814 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 1806 may also be used for storing data that is manipulated by the processor 1804 when executing software. The processing system 1814 also includes at least one of the components 1704, 1706, 1708. The components may be software components running in the processor 1804, resident/stored in the computer readable medium/memory 1806, one or more hardware components coupled to the processor 1804, or some combination thereof. The processing system 1814 may be a component of the base station 310 and may include the TX processor 316, the RX processor 370, and at least one of the controller/processor 375 and/or the memory 376.

In certain aspects, the means 1702/1702' for wireless communication may comprise: means for determining a narrowband TDD frame structure for narrowband communication from a set of narrowband TDD frame structures. In one aspect, the at least one common subframe in each narrowband TDD frame structure in the set of narrowband TDD frame structures may be configured as a downlink subframe. In another aspect, the SSS may be transmitted using at least one common subframe in a narrowband TDD frame structure determined for narrowband communication. In a further aspect, the set of narrowband TDD frame structures may include a subset of all narrowband TDD frame structures available for narrowband communication. In certain other aspects, the means for wireless communicating 1702/1702' may comprise: means for determining a predetermined distance between transmitting the PSS and the SSS. In an aspect, the predetermined distance may be configured to communicate information associated with the narrowband communication to the UE. In another aspect, the information may include at least one of: TDD mode, FDD mode, narrowband TDD frame structure determined for narrowband communications, or bandwidth associated with TDD mode. In certain other aspects, the means for wireless communicating 1702/1702' may comprise: means for transmitting the PSS using a narrowband TDD frame structure determined for narrowband communication. In an aspect, the PSS may be transmitted on a different resource block than the SSS. In another aspect, the PSS may be transmitted using a specific subframe. In further aspects, the PSS may not be transmitted in every frame. In a further aspect, the SSS may be transmitted using a specific subframe in at least one frame in which the PSS is not transmitted. In yet another aspect, the PSS may be transmitted using a particular subframe in every other subframe. In a further aspect, the SSS may be transmitted using subframes other than the specific subframes in each frame in which the PSS is not transmitted. In certain other aspects, the means for wireless communicating 1702/1702' may comprise: means for transmitting the SSS using the narrowband TDD frame structure determined for narrowband communication. In an aspect, the SSS may be transmitted using the same subframe in at most every other frame. In another aspect, a period associated with transmitting the SSS using the narrowband TDD frame structure may be reduced as compared to a period associated with transmission of the second SSS using the narrowband FDD frame structure. In a further aspect, at least one of a periodicity associated with transmitting the SSS, a time location associated with transmitting the SSS, or a frequency location associated with transmitting the SSS is related to a narrowband TDD frame structure determined for narrowband communications. The aforementioned means may be one or more of the aforementioned components of the apparatus 1702 and/or the processing system 1814 of the apparatus 1702' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 1814 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

Fig. 19 is a conceptual data flow diagram 1900 illustrating the data flow between different units/components in an exemplary apparatus 1902. The apparatus may be a base station (e.g., base station 102, 180, 310, 504, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902 ', 2302/2302') in narrowband communication (e.g., NB-IoT communication or eMTC) with a UE 1950 (e.g., UE 104, 350, 506, 1150, 1350, 1550, 1750, 2350). The apparatus can include a receiving component 1904, a determining component 1906, and a sending component 1908.

The determining component 1906 can be configured to determine a narrowband TDD frame structure for narrowband communications from a set of narrowband TDD frame structure configurations. In some other configurations, the determining component 1906 may be configured to: a narrowband communication frame structure comprising an FDD frame structure or a TDD frame structure is determined and a narrowband TDD frame structure configuration for narrowband communication is determined from a set of narrowband TDD frame structure configurations. In some other configurations, the determining component 1906 may be configured to: determining one or more narrowband carriers and subframes within the one or more narrowband carriers based on the narrowband communication frame structure or the TDD frame structure configuration to send at least one of a BCH or a SIB 1. The determining component 1906 may be configured to transmit a signal 1901 to the transmitting component 1908, the signal 1901 including information associated with a narrowband TDD frame structure for narrowband communications.

The transmitting component 1908 may be configured to transmit the PSS1903, SSS1903, and BCH1903 using the narrowband TDD frame structure determined for narrowband communications. In certain other configurations, transmitting component 1908 may be configured to transmit PSS1903, SSS1903, and at least one of BCH1903 or SIB 11903 using a narrowband TDD frame structure determined for narrowband communications. In an aspect, the carrier used to transmit the BCH1903 and/or SIB 11903 may be different from the carrier used to transmit one or more of the PSS1903 or SSS 1903. In another aspect, the narrowband carrier used to transmit the BCH1903 may be different from the narrowband carrier used to transmit one or more of the PSS1903 or SSS 1903. In another aspect, the BCH1903 may be transmitted using one or more subframes in each radio frame. In certain other aspects, the SSS1903 may be transmitted using a particular subframe in every other frame. In certain other aspects, the BCH1903 may be transmitted using a particular subframe in each frame in which the SSS1903 is not transmitted. In certain other aspects, the periodicity associated with transmitting the BCH1903 may be used to indicate whether an FDD frame structure or a TDD frame structure is being used for narrowband communication. In certain other aspects, at least one of a periodicity associated with transmitting the BCH1903, a time location associated with transmitting the BCH1903, or a frequency location associated with transmitting the BCH1903 may be related to one or more of: a narrowband TDD frame structure determined for narrowband communications, a second carrier containing PSS1903 or SSS1903, or information transmitted over PSS1903 or SSS 1903. In certain other aspects, the first carrier used to transmit the BCH1903 may be located at a fixed frequency offset with respect to the second carrier used to transmit one or more of the PSS1903 or the SSS 1903. In certain other aspects, the BCH1903 includes information indicative of at least one of: a narrowband TDD frame structure configuration determined for narrowband communication, whether the narrowband communication usage uses an FDD frame structure or a TDD frame structure, or a carrier location or subframe location associated with SIB 11903. In certain other aspects, the information may be included in the BCH1903 by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits. In certain other aspects, the first carrier may be used to transmit both the BCH1903 and the SIB 11903 when the first carrier is different from the second carrier used to transmit the PSS1903 and the SSS 1903. In certain other aspects, the SIB 11903 may be transmitted using a different carrier than the first carrier used to transmit the BCH 1903. In certain other aspects, at least one of the narrowband carrier location relative to the PSS1903 carrier location or the subframe in which the SIB 11903 is transmitted may be associated with a narrowband frame structure determined for narrowband communication. In an aspect, the resource blocks used to transmit the BCH1903 may be different than the resource blocks used to transmit one or more of the PSS1903 or the SSS 1903. In another aspect, the BCH1903 may be transmitted using one or more subframes in each radio frame. In further aspects, the SSS1903 may be transmitted using a particular subframe in every other frame. In yet another aspect, the BCH1903 may be transmitted using a specific subframe in each frame in which the SSS is not transmitted. In further aspects, a first periodicity associated with transmitting the BCH1903 using a narrowband TDD frame structure may be reduced compared to a second periodicity associated with transmitting the BCH1903 using an FDD frame structure. In another aspect, a CRC mask can be included in BCH1903 to indicate the narrowband TDD frame structure. In another aspect, at least one of a periodicity associated with transmitting the BCH1903, a time location associated with transmitting the BCH, or a frequency location associated with transmitting the BCH1903 may be related to a narrowband TDD frame structure determined for narrowband communications. In another aspect, the BCH1903 may include at least one of: a first bit indicating a narrowband TDD frame structure determined for narrowband communication, a second bit indicating an FDD frame structure determined for narrowband communication, or information indicating a resource block location or subframe location associated with SIB 1903. The transmitting component 1908 can be configured to transmit SIB1903 using a narrowband TDD frame structure determined for narrowband communication. In an aspect, the SIB1903 may be transmitted using the same resource blocks as used for transmitting one or more of the PSS1903, SSS1903, or BCH 1903. In another aspect, the SIB1903 may be transmitted using a different resource block than the resource block used to transmit one or more of the PSS1903, SSS1903, or BCH 1903. In further aspects, at least one of the resource blocks or subframes used to transmit SIB1903 may be associated with a narrowband TDD frame structure determined for narrowband communication. The transmitting component 1908 may be configured to transmit information indicating a subframe including NRS 1903. In one aspect, the information may comprise a bitmap. The transmitting component 1908 may be configured to transmit the NRS1903 using a narrowband TDD frame structure determined for narrowband communications. In an aspect, NRS1903 may be transmitted using a subframe that is also used for transmission of SIB1903 and BCH 1903. In another aspect, the NRS1903 may be transmitted using different resource blocks than the resource blocks used to transmit at least one of the PSS1903 or SSS 1903. In another aspect, the same subframe used to transmit NRS1903, SIB1903, and BCH1903 may not be a function of the narrowband TDD frame structure determined for narrowband communications. In further aspects, the same subframe used to transmit NRS1903, SIB1903, and BCH1903 may be a function of the narrowband TDD frame structure determined for narrowband communications. In another aspect, the density of NRS1903 transmitted using a narrowband TDD frame structure may be increased compared to the density of NRS1903 transmitted using a narrowband FDD frame structure. In yet another aspect, NRS1903 may be transmitted in the same subframe used to transmit CRS. In further aspects, NRS1903 may be transmitted in a downlink portion of a special subframe in a narrowband TDD frame structure determined for narrowband communications. In one aspect, the symbols used to transmit NRS in the downlink portion of the special subframe may be the same as the symbols used to transmit NRS in the downlink subframe in the narrowband TDD frame structure. In another aspect, the uplink portion of the special subframe may be punctured. In a further aspect, the symbols used to transmit NRS1903 in the downlink portion of the special subframe may be different from the symbols used to transmit NRS1903 in the downlink subframe in the narrowband TDD frame structure.

The receiving component 1904 and/or the transmitting component 1908 can be configured to communicate 1903, 1905 with the UE 1950 using a narrowband TDD frame structure determined for narrowband communication. For example, the receiving component 1904 may be configured to receive the narrowband uplink transmission 1905 from the UE 1950. The transmitting component 1908 may be configured to transmit one or more narrowband downlink transmissions 1903 to the UE 1950.

The apparatus may include additional components to perform each of the blocks of the algorithm in the flowcharts of fig. 10 and 25 described above. As such, each block in the flowcharts of fig. 10 and 25 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process/algorithm, implemented by a processor configured to perform the process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Figure 20 is a diagram 2000 illustrating an example of a hardware implementation of an apparatus 1902' employing a processing system 2014. The processing system 2014 may be implemented with a bus architecture, represented generally by the bus 2024. The bus 2024 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 2014 and the overall design constraints. The bus 2024 links together various circuits including one or more processors and/or hardware components (represented by the processor 2004), the components 1904, 1906, 1908, and the computer-readable medium/memory 2006. The bus 2024 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2014 may be coupled to a transceiver 2010. The transceiver 2010 is coupled to one or more antennas 2020. The transceiver 2010 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2010 receives the signal from the one or more antennas 2020, extracts information from the received signal, and provides the extracted information to the processing system 2014 (specifically, the receiving component 1904). Additionally, the transceiver 2010 receives information from the processing system 2014 (and in particular the transmitting component 1908) and generates a signal to be applied to the one or more antennas 2020 based on the received information. The processing system 2014 includes a processor 2004 coupled to a computer-readable medium/memory 2006. The processor 2004 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 2006. The software, when executed by the processor 2004, causes the processing system 2014 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 2006 may also be used for storing data that is manipulated by the processor 2004 when executing software. The processing system 2014 also includes at least one of the components 1904, 1906, 1908. The components may be software components running in the processor 2004, resident/stored in the computer readable medium/memory 2006, one or more hardware components coupled to the processor 2004, or some combination thereof. The processing system 2014 may be a component of the base station 310 and may include the TX processor 316, the RX processor 370, at least one of the controller/processor 375, and/or the memory 376.

In certain aspects, the means 1902/1902' for wireless communication may comprise: the apparatus includes means for determining a narrowband TDD frame structure for narrowband communication from a set of narrowband TDD frame structure configurations. In certain other aspects, the means for wireless communicating 1902/1902' may comprise: means for transmitting the PSS, SSS, and BCH using a narrowband TDD frame structure determined for narrowband communication. In an aspect, the resource blocks used to transmit the BCH may be different than the resource blocks used to transmit one or more of the PSS or SSS. In another aspect, the BCH may be transmitted using one or more subframes in each radio frame. In further aspects, the SSS may be transmitted using a particular subframe in every other frame. In yet another aspect, the BCH may be transmitted using a particular subframe in each frame in which the SSS is not transmitted. In further aspects, a first periodicity associated with transmitting the BCH using the narrowband TDD frame structure may be reduced as compared to a second periodicity associated with transmitting the BCH using the FDD frame structure. In another aspect, a CRC mask may be included in the BCH to indicate the narrowband TDD frame structure. In another aspect, at least one of a periodicity associated with transmitting the BCH, a time location associated with transmitting the BCH, or a frequency location associated with transmitting the BCH can be related to a narrowband TDD frame structure determined for narrowband communications. In another aspect, the BCH may include at least one of: a first bit indicating a narrowband TDD frame structure determined for narrowband communication, a second bit indicating an FDD frame structure determined for narrowband communication, or information indicating a resource block location or subframe location associated with a SIB. In certain other aspects, the means for wireless communicating 1902/1902' may comprise: means for transmitting a system information block using a narrowband TDD frame structure determined for narrowband communication. In an aspect, the SIBs may be transmitted using the same resource blocks used to transmit one or more of the PSS, SSS, or BCH. In another aspect, the SIBs may be transmitted using different resource blocks than the resource blocks used to transmit one or more of the PSS, SSS, or BCH. In further aspects, at least one of a resource block or a subframe used to transmit the SIB may be associated with a narrowband TDD frame structure determined for narrowband communication. In certain other aspects, the means for wireless communicating 1902/1902' may comprise: means for transmitting information indicating a subframe including an NRS. In one aspect, the information may comprise a bitmap. In certain other aspects, the means for wireless communicating 1902/1902' may comprise: means for transmitting the NRS using the narrowband TDD frame structure determined for narrowband communication. In an aspect, NRS may be transmitted using subframes that are also used for transmitting SIBs and BCH. In another aspect, the NRS may be transmitted using different resource blocks than the resource blocks used to transmit at least one of the PSS or SSS. In another aspect, the same subframe used to transmit the NRS, SIB, and BCH may not be a function of the narrowband TDD frame structure determined for narrowband communication. In further aspects, the same subframe used for transmitting the NRS, SIB, and BCH may be a function of the narrowband TDD frame structure determined for narrowband communication. In another aspect, the density of NRSs transmitted using a narrowband TDD frame structure may be increased compared to the density of NRSs transmitted using a narrowband FDD frame structure. In yet another aspect, the NRS is transmitted in the same subframe used to transmit the CRS. In further aspects, the NRS may be transmitted in a downlink portion of a special subframe in a narrowband TDD frame structure determined for narrowband communications. In one aspect, the symbols used to transmit NRS in the downlink portion of the special subframe may be the same as the symbols used to transmit NRS in the downlink subframe in the narrowband TDD frame structure. In another aspect, the uplink portion of the special subframe may be punctured. In a further aspect, the symbols used to transmit NRS in the downlink portion of the special subframe may be different from the symbols used to transmit NRS in the downlink subframe in the narrowband TDD frame structure. In certain aspects, the means 1902/1902' for wireless communication may comprise: the apparatus includes means for determining a narrowband communication frame structure comprising an FDD frame structure or a TDD frame structure and determining a narrowband TDD frame structure configuration for narrowband communication from a set of narrowband TDD frame structure configurations. In certain other aspects, the means for wireless communicating 1902/1902' may comprise: means for determining one or more narrowband carriers and subframes within the one or more narrowband carriers based on the narrowband communication frame structure or TDD frame structure configuration to send at least one of a BCH or a SIB 1. In certain other aspects, the means for wireless communicating 1902/1902' may comprise: means for transmitting the PSS, the SSS, and at least one of the BCH or the SIB1 using a narrowband TDD frame structure determined for narrowband communication. In an aspect, the carrier used to transmit the BCH and/or SIB may be different from the carrier used to transmit one or more of the PSS or SSS. In another aspect, the narrowband carrier used to transmit the BCH may be different from the narrowband carrier used to transmit one or more of the PSS or SSS. In another aspect, the BCH may be transmitted using one or more subframes in each radio frame. In certain other aspects, the SSS may be transmitted using a particular subframe in every other frame. In certain other aspects, the BCH may be transmitted using a particular subframe in each frame in which the SSS is not transmitted. In certain other aspects, a periodicity associated with transmitting the BCH may be used to indicate whether an FDD frame structure or a TDD frame structure is being used for narrowband communication. In certain other aspects, at least one of a periodicity associated with transmitting the BCH, a time location associated with transmitting the BCH, or a frequency location associated with transmitting the BCH can be related to one or more of: a narrowband TDD frame structure determined for narrowband communications, a second carrier containing a PSS or SSS, or information transmitted over a PSS or SSS. In certain other aspects, the first carrier used to transmit the BCH may be located at a fixed frequency offset with respect to the second carrier used to transmit one or more of the PSS or SSS. In certain other aspects, the BCH includes information indicative of at least one of: a narrowband TDD frame structure configuration determined for narrowband communication, whether the narrowband communication usage uses an FDD frame structure or a TDD frame structure, or a carrier location or subframe location associated with SIB 1. In certain other aspects, the information may be included in the BCH by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits. In certain other aspects, the first carrier may be used to transmit both BCH and SIB1 when the first carrier is different from the second carrier used to transmit PSS and SSS. In certain other aspects, the SIB1 may be transmitted using a different carrier than the first carrier used to transmit the BCH. In certain other aspects, at least one of the narrowband carrier location relative to the PSS carrier location or the subframe used to transmit the SIB1 may be associated with a narrowband frame structure determined for narrowband communication. The aforementioned means may be one or more of the aforementioned components of apparatus 1902 and/or the processing system 2014 of apparatus 1902' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 2014 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

Fig. 21 is a diagram illustrating a data flow 2100 that may be used for narrowband communication in accordance with certain aspects of the present disclosure. For example, data flow 2100 can be performed by base station 2104 and/or UE 2106. The base station 2104 may correspond to, for example, base stations 102, 180, 504, eNB 310, apparatuses 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'. The UE2106 may correspond to, for example, the UE 104, 350, 506, 1150, 1350, 1550, 1750, 1950, 2350. Additionally, the base station 2104 and the UE2106 may be configured to communicate using narrowband communication 2109 (e.g., NB-IoT and/or eMTC). For example, the UE2106 may be an NB-IoT device and/or an eMTC device.

In one aspect, base station 2104 may determine 2101 a narrowband TDD frame structure for narrowband communication. The narrowband TDD frame structure may include one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, and/or a flexible subframe set. For example, base station 2104 may determine 2101 narrowband TDD frame structure is one of configurations 0, 1, 2, 3, 4, 5, 6, l, or o from table 410 in fig. 4.

In another aspect, the base station 2104 may transmit a bitmap 2103 associated with a narrowband TDD frame structure to the UE 2106. The bitmap 2103 can indicate a set of downlink subframes, a set of uplink subframes, a set of special subframes, and/or a set of flexible subframes in the determined narrowband TDD frame structure.

In an aspect, when the base station 2104 operates in a in-band mode, a single bitmap 2103 may be transmitted to the UE2106, the bitmap 2103 indicating a set of downlink subframes, a set of uplink subframes, a set of special subframes, and/or a set of flexible subframes. Alternatively, when the base station 2104 operates in the standalone mode, the first bitmap 2103 indicating a downlink subframe set, the second bitmap 2103 indicating an uplink subframe set, the third bitmap 2103 indicating a special subframe set, and/or the fourth bitmap 2103 indicating a flexible subframe set may be transmitted separately to the UE 2106.

In certain aspects, a first length of a bitmap 2103 associated with the determined narrowband TDD frame structure may be longer than a second length of a different bitmap associated with a narrowband FDD frame structure. For example, a single bitmap of length N (e.g., N-60) may be used to indicate one or more of downlink subframes and/or uplink subframes in a narrowband FDD frame structure. In certain aspects, the length N of the bitmap 2103 indicating available downlink subframes, uplink subframes, special subframes, and/or flexible subframes in the narrowband TDD frame structure may be greater (e.g., N-80) than a bitmap indicating a narrowband FDD frame structure. The length of the narrowband TDD frame structure bitmap may be greater than the narrowband FDD frame structure bitmap because there may be more types of subframes (e.g., uplink subframes, downlink subframes, special subframes, and/or flexible subframes) available for allocation using the narrowband TDD frame structure than the narrowband FDD frame structure (e.g., uplink subframes and/or downlink subframes).

When base station 2104 allocates one or more flexible subframes for NPDCCH and/or NPDSCH, UE2106 may decode NRS and NPDCCH and/or NPDSCH transmitted on the allocated flexible subframes. When base station 2104 allocates one or more flexible subframes for NPUCCH and/or NPUSCH, UE2106 may transmit NPUCCH and/or NPUSCH using the allocated flexible subframes. The UE2106 may ignore the flexible subframe when the flexible subframe is not allocated for NPDCCH, NPDSCH, NPUCCH, or NPUSCH. For example, UE2106 may not perform NRS detection on a flexible subframe when the flexible subframe is not allocated for NPDCCH, NPDSCH, NPUCCH, or NPUSCH.

Fig. 22 is a flow chart 2200 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, 2104, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'). In fig. 22, optional operations are indicated by broken lines.

At 2202, a base station may determine a narrowband TDD frame structure for narrowband communications. In one aspect, the narrowband TDD frame structure may include one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In an aspect, the flexible subframes may be configured by the base station as downlink subframes or uplink subframes. For example, referring to fig. 21, base station 2104 may determine 2101 a narrowband TDD frame structure for narrowband communications, the narrowband TDD frame structure comprising one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, and/or a flexible subframe set. For example, base station 2104 may determine 2101 narrowband TDD frame structure is one of configurations 0, 1, 2, 3, 4, 5, 6, l, or o from table 410 in fig. 4.

At 2204, the base station may transmit a bitmap associated with the narrowband TDD frame structure to the UE. In an aspect, the bitmap may indicate one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In another aspect, a first length of a bitmap associated with a narrowband TDD frame structure may be longer than a second length of a different bitmap associated with a narrowband FDD frame structure. For example, referring to fig. 21, base station 2104 may transmit a bitmap 2103 associated with a narrowband TDD frame structure to UE 2106. The bitmap 2103 can indicate a set of downlink subframes, a set of uplink subframes, a set of special subframes, and/or a set of flexible subframes in the determined narrowband TDD frame structure.

At 2206, the base station may transmit a bitmap associated with the narrowband TDD frame structure to the UE by transmitting a single bitmap indicating one or more of a set of downlink subframes, a set of uplink subframes, a set of special subframes, or a set of flexible subframes. For example, referring to fig. 21, when the base station 2104 operates in a in-band mode, a single bitmap 2103 may be transmitted to the UE2106, the bitmap 2103 indicating a downlink subframe set, an uplink subframe set, a special subframe set, and/or a flexible subframe set.

At 2208, the base station may transmit a bitmap associated with the narrowband TDD frame structure to the UE by transmitting first information indicating a set of downlink subframes. For example, referring to fig. 21, when the base station 2104 operates in standalone mode, a first bitmap 2103 indicating a set of downlink subframes may be separately transmitted to the UE 2106.

At 2210, the base station may transmit a bitmap associated with the narrowband TDD frame structure to the UE by transmitting second information indicating a set of uplink subframes. For example, referring to fig. 21, when the base station 2104 operates in standalone mode, a second bitmap 2103 indicating a set of uplink subframes may be separately transmitted to the UE 2106.

At 2212, the base station may transmit a bitmap associated with the narrowband TDD frame structure to the UE by transmitting third information indicating the set of special subframes. For example, referring to fig. 21, when the base station 2104 operates in standalone mode, a third bitmap 2103 indicating a set of special subframes may be separately transmitted to the UE 2106.

At 2214, the base station may transmit a bitmap associated with the narrowband TDD frame structure to the UE by transmitting fourth information indicating the flexible set of subframes. For example, referring to fig. 21, when the base station 2104 operates in standalone mode, the fourth bitmap 2103 indicating a flexible set of subframes may be separately transmitted to the UE 2106.

Fig. 23 is a conceptual data flow diagram 2300 illustrating the data flow between different units/components in an exemplary apparatus 2302. The apparatus may be a base station (e.g., base station 102, 180, 310, 504, 2104, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302') in narrowband communication (e.g., NB-IoT communication or eMTC) with a UE 2350 (e.g., UE 104, 350, 506, 1150, 1350, 1550, 1950, 2104). The apparatus may include a receiving component 2304, a determining component 2306, and a sending component 2308.

The determining component 2306 may be configured to determine a narrowband TDD frame structure for narrowband communications. In one aspect, the narrowband TDD frame structure may include one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In an aspect, the flexible subframes may be configured by the base station as downlink subframes or uplink subframes. Determining component 2306 can transmit a signal 2301 to transmitting component 2308, signal 2301 including information associated with a narrowband TDD frame structure having one or more of a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set.

A transmitting component 2308 may transmit a bitmap 2303 associated with the narrowband TDD frame structure to a UE 2350. In an aspect, the bitmap may indicate one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In another aspect, a first length of a bitmap associated with a narrowband TDD frame structure may be longer than a second length of a different bitmap associated with a narrowband FDD frame structure. In certain aspects, the send component 2308 may be configured to: the bitmap 2303 associated with the narrowband TDD frame structure is transmitted to the UE 2350 by transmitting first information indicating a set of downlink subframes. In certain other aspects, the send component 2308 may be configured to: the bitmap 2303 associated with the narrowband TDD frame structure is transmitted to the UE 2350 by transmitting second information indicating a set of uplink subframes. In certain other aspects, the send component 2308 may be configured to: the bitmap 2303 associated with the narrowband TDD frame structure is transmitted to the UE 2350 by transmitting third information indicating a set of special subframes. In certain other aspects, the send component 2308 may be configured to: the bitmap 2303 associated with the narrowband TDD frame structure is transmitted to the UE 2350 by transmitting fourth information indicating a flexible subframe set.

The receiving component 2304 and/or the transmitting component 2308 may be configured to communicate 2303, 2305 with the UE 1750 using the narrowband TDD frame structure determined for narrowband communication. For example, receiving component 2304 may be configured to receive narrowband uplink transmission 2305 from UE 2350. Transmitting component 2308 may be configured to transmit one or more narrowband downlink transmissions 2303 to UE 2350.

The apparatus may include additional components to perform each of the blocks of the algorithm in the flow chart of fig. 22 described above. As such, each block in the flow diagram of fig. 22 described above may be performed by a component, and the apparatus may include one or more of those components. The components may be one or more hardware components specifically configured to perform the process/algorithm, implemented by a processor configured to perform the process/algorithm, stored within a computer-readable medium for implementation by a processor, or some combination thereof.

Fig. 24 is a diagram 2400 illustrating an example of a hardware implementation of an apparatus 2302' employing a processing system 2414. The processing system 2414 may be implemented with a bus architecture, represented generally by the bus 2424. The bus 2424 may include any number of interconnected buses and bridges depending on the particular application of the processing system 2414 and the overall design constraints. The bus 2424 links together various circuits including one or more processors and/or hardware components (represented by the processor 2404), the components 2304, 2306, 2308, and the computer-readable medium/memory 2406. The bus 2424 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further.

The processing system 2414 may be coupled to a transceiver 2410. The transceiver 2410 is coupled to one or more antennas 2420. The transceiver 2410 provides a means for communicating with various other apparatus over a transmission medium. The transceiver 2410 receives signals from the one or more antennas 2420, extracts information from the received signals, and provides the extracted information to the processing system 2414 (and in particular the receive component 2304). Additionally, the transceiver 2410 receives information from the processing system 2414 (and in particular the transmit component 2308) and generates signals that are applied to the one or more antennas 2420 based on the received information. The processing system 2414 includes a processor 2404 coupled to a computer-readable medium/memory 2406. The processor 2404 is responsible for general processing, including the execution of software stored on the computer-readable medium/memory 2406. The software, when executed by the processor 2404, causes the processing system 2414 to perform the various functions described supra for any particular apparatus. The computer-readable medium/memory 2406 may also be used for storing data that is manipulated by the processor 2404 when executing software. The processing system 2414 also includes at least one of the components 2304, 2306, 2308. The components may be software components running in the processor 2404, resident/stored in the computer readable medium/memory 2406, one or more hardware components coupled to the processor 2404, or some combination thereof. The processing system 2414 may be a component of the base station 310 and may include the TX processor 316, the RX processor 370, and at least one of the controller/processor 375 and/or the memory 376.

In certain aspects, the means 2302/2302' for wireless communication may comprise: means for determining a narrowband TDD frame structure for narrowband communication. In one aspect, the narrowband TDD frame structure may include one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In an aspect, the flexible subframes may be configured by the base station as downlink subframes or uplink subframes. In certain other aspects, the means for wireless communicating 2302/2302' may comprise: means for transmitting a bitmap associated with a narrowband TDD frame structure to a UE. In an aspect, the bitmap may indicate one or more of: a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In another aspect, a first length of a bitmap associated with a narrowband TDD frame structure may be longer than a second length of a different bitmap associated with a narrowband FDD frame structure. In certain aspects, the means for transmitting a bitmap associated with a narrowband TDD frame structure to a UE may be configured to: transmitting a single bitmap indicating one or more of a downlink subframe set, an uplink subframe set, a special subframe set, or a flexible subframe set. In certain aspects, the means for transmitting a bitmap associated with a narrowband TDD frame structure to a UE may be configured to: first information indicating a set of downlink subframes is transmitted. In certain aspects, the means for transmitting a bitmap associated with a narrowband TDD frame structure to a UE may be configured to: transmitting second information indicating a set of uplink subframes. In certain aspects, the means for transmitting a bitmap associated with a narrowband TDD frame structure to a UE may be configured to: transmitting third information indicating the special subframe set. In certain aspects, the means for transmitting a bitmap associated with a narrowband TDD frame structure to a UE may be configured to: transmitting fourth information indicating a flexible subframe set. The aforementioned means may be one or more of the aforementioned components of the apparatus 2302 and/or the processing system 2414 of the apparatus 2302' configured to perform the functions recited by the aforementioned means. As described supra, the processing system 2414 may include the TX processor 316, the RX processor 370, and the controller/processor 375. As such, in one configuration, the aforementioned means may be the TX processor 316, the RX processor 370, and the controller/processor 375 configured to perform the functions recited by the aforementioned means.

Fig. 25 is a flow chart 2500 of a method of wireless communication. The method may be performed by a base station (e.g., base station 102, 180, 504, eNB 310, apparatus 1102/1102 ', 1302/1302', 1502/1502 ', 1702/1702', 1902/1902 ', 2302/2302'). In fig. 25, an optional operation is indicated by a dotted line.

At 2502, the base station may determine a narrowband TDD frame structure for narrowband communications from a set of narrowband TDD frame structures. For example, referring to fig. 5B-5D, base station 504 may determine 515 a narrowband TDD frame structure for narrowband communication 509 from a set of narrowband TDD frame structures (e.g., the configurations listed in table 410 in fig. 4).

At 2504, the base station may determine a set of narrowband carriers and a minimum set of subframes on the set of narrowband carriers based at least in part on a set of downlink subframes and special subframes on which NRS should be transmitted. In certain aspects, the minimum set of subframes for transmitting NRS may not be a function of the narrowband TDD frame structure determined for narrowband communications. In certain other aspects, the minimum set of subframes may be limited to subframes that are downlink subframes or special subframes in all supported TDD frame structures for narrowband communication. In certain other aspects, the minimum set of subframes for transmitting NRS may be a function of the narrowband TDD frame structure determined for narrowband communications. For example, referring to fig. 5B-5D, base station 504 may determine a set of narrowband carriers and a set of minimum subframes (e.g., common subframes described above) on which NRS 541 should be transmitted. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NRS 541 may be transmitted on one of subframe 0 or subframe 5 because subframes 0 and 5 are common downlink subframes in each configuration in the group. Further, NRS 541 may be transmitted on subframe 1 or subframe 6 because subframes 1 and 6 are special subframes (e.g., which include downlink resources) or downlink subframes in each of configurations 0, 1, 2, 3, 4, 5, 6, and m. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NRS 541 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. Alternatively, base station 504 may transmit NRS 541 in a downlink subframe that is not a function of the determined narrowband TDD frame structure. For example, NPBCH535 transmitted by base station 504 may be used to indicate to UE506 the downlink subframe that includes NRS 541 when the downlink subframe used to transmit NRS 541 is not a function of the determined narrowband TDD frame structure. In certain aspects, a bitmap 539 may be included in the NPBCH 535.

At 2506, the base station may transmit information indicating an additional subframe for transmitting NRS. In one aspect, the information may include broadcast signaling. For example, referring to fig. 5B-5D, base station 504 may transmit NRS 541 in downlink subframes that are not a function of the determined narrowband TDD frame structure. For example, NPBCH535 (e.g., broadcast signaling) transmitted by base station 504 may be used to indicate to UE506 the downlink subframe that includes NRS 541 when the downlink subframe used to transmit NRS 541 is not a function of the determined narrowband TDD frame structure.

At 2508, the base station may transmit NRS using the narrowband TDD frame structure determined for narrowband communication. In an aspect, NRS may be transmitted using subframes that are also used for transmitting SIBs and BCH. In another aspect, the NRS may be transmitted using different resource blocks than the resource blocks used to transmit at least one of the PSS or SSS. In another aspect, the same subframe used to transmit the NRS, SIB, and BCH may not be a function of the narrowband TDD frame structure determined for narrowband communication. In further aspects, the same subframe used for transmitting the NRS, SIB, and BCH may be a function of the narrowband TDD frame structure determined for narrowband communication. In another aspect, the density of NRSs transmitted using a narrowband TDD frame structure may be increased compared to the density of NRSs transmitted using a narrowband FDD frame structure. In yet another aspect, the NRS is transmitted in symbols and resource elements used to transmit the CRS. In further aspects, the NRS may be transmitted in a downlink portion of a special subframe in a narrowband TDD frame structure determined for narrowband communications. In one aspect, the symbols used to transmit NRS in the downlink portion of the special subframe may be the same as the symbols used to transmit NRS in the downlink subframe in the narrowband TDD frame structure. In another aspect, any NRS symbols present in the uplink portion of the special subframe may be punctured. In a further aspect, the symbols used to transmit NRS in the downlink portion of the special subframe may be different from the symbols used to transmit NRS in the downlink subframe in the narrowband TDD frame structure. In certain aspects, the symbols used to transmit the NRS are determined based on the number of downlink symbols in the special subframe configuration. For example, referring to fig. 5B-5D, base station 504 may transmit NRS 541 using a narrowband TDD frame structure determined for narrowband communication 509. For example, the base station 504 can transmit NRSs using subframes that are also used to transmit SIBs 537 and/or NPBCH 535. Additionally, NRS 541 may be transmitted using a different RB than the RBs used to transmit NPSS521 and/or NSSS 529. In certain aspects, base station 504 may transmit NRS 541 using one of the common subframes described above. For example, when the narrowband TDD frame structure is determined from one of configurations 0, 1, 2, 3, 4, 5, 6, and m, NRS 541 may be transmitted on one of subframe 0 or subframe 5 because subframes 0 and 5 are common downlink subframes in each configuration in the group. Further, NRS 541 may be sent on subframe 1 or subframe 6 because subframes 1 and 6 are special subframes (e.g., which include downlink resources) or downlink subframes in each configuration in the group. In another example, when the narrowband TDD frame structure is determined from one of configurations 1, 2, 3, 4, 5, and 6, NRS 541 may be transmitted on one of subframe 0, subframe 5, or subframe 9 because subframes 0, 5, and 9 are common downlink subframes in each configuration in the group. NRS 541 may be transmitted in the DwPTS portion of the special subframe (e.g., see fig. 4) and the downlink subframe in the determined narrowband TDD frame structure. In an aspect, the same symbol in the DwPTS portion of the special subframe and the downlink subframe may be used for transmitting NRS 541. When the NRS 541 is transmitted in the DwPTS of the special subframe, the UpPTS portion of the special subframe may be punctured. In certain aspects, the NRS 541 transmitted using the narrowband TDD frame structure may be more dense than the NRS transmitted using the narrowband FDD frame structure. In other configurations, NRS 541 may be transmitted in symbols and resource elements used by base station 504 to transmit CRS.

It should be understood that the specific order or hierarchy of blocks in the processes/flow diagrams disclosed is merely illustrative of exemplary approaches. It should be understood that the particular order or hierarchy of blocks in the processes/flow diagrams may be rearranged based on design preferences. Further, some blocks may be combined or omitted. The accompanying method claims present elements of the various blocks in a sample order, and are not meant to be limited to the specific order or hierarchy presented.

The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more. The word "exemplary" is used herein to mean "serving as an example, instance, or illustration. Any aspect described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other aspects. The term "some" means one or more unless explicitly stated otherwise. Combinations such as "A, B or at least one of C", "A, B, or one or more of C", "at least one of A, B and C", "one or more of A, B and C", and "A, B, C or any combination thereof" include any combination of A, B and/or C, and may include multiples of a, multiples of B, or multiples of C. In particular, combinations such as "at least one of A, B or C", "A, B, or one or more of C", "at least one of A, B and C", "one or more of A, B and C", and "A, B, C or any combination thereof" may be a only, B only, C, A and B, A and C, B and C only, or a and B and C only, wherein any such combination may comprise one or more members or several members of A, B or C. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. The words "module," mechanism, "" element, "" device, "and the like may not be a substitute for the word" unit. Thus, no claim element is to be construed as a functional unit unless the element is explicitly recited using the phrase "unit for … …".

Claims

1. A method of wireless communication for a base station, comprising:

determining a time division duplex, TDD, frame structure and determining a TDD frame structure configuration for narrowband communications from a set of TDD frame structures having different downlink and uplink subframe configurations;

determining one or more narrowband carriers and subframes within the one or more narrowband carriers based on the TDD frame structure configuration to send at least one of a Broadcast Channel (BCH) or a system information block 1 (SIB) 1; and

transmitting a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and the at least one of the BCH or the SIB1 using the TDD frame structure determined for the narrowband communication, wherein a first carrier is used for transmitting the at least one of the BCH or the SIB1, the first carrier being different from a second carrier used for transmitting one or more of the PSS or the SSS.

2. The method of claim 1, wherein a narrowband carrier used to transmit the BCH is different from a narrowband carrier used to transmit one or more of the PSS or the SSS.

3. The method of claim 1, wherein the BCH is transmitted using one or more subframes in each radio frame.

4. The method of claim 1, wherein:

the SSS is transmitted using a specific subframe in every other frame; and

the BCH is transmitted using the specific subframe in each frame in which the SSS is not transmitted.

5. The method of claim 1, wherein a periodicity associated with the transmitting the BCH indicates that the TDD frame structure is used for the narrowband communication.

6. The method of claim 1, wherein at least one of a periodicity associated with the transmitting the BCH, a time location associated with the transmitting the BCH, or a frequency location associated with the transmitting the BCH is related to one or more of: the TDD frame structure determined for narrowband communication, the second carrier containing the PSS or the SSS, or information sent on the PSS or the SSS.

7. The method of claim 6, wherein the first carrier used to transmit the BCH is located at a fixed frequency offset with respect to the second carrier used to transmit the one or more of the PSS or SSS.

8. The method of claim 1, wherein the BCH indicates at least one of: the TDD frame structure configuration determined for the narrowband communication, or a carrier location or subframe location associated with the SIB 1.

9. The method of claim 8, wherein the information is included in the BCH by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits.

10. The method of claim 1, wherein the first carrier is used to transmit both the BCH and the SIB1 when the first carrier is different from the second carrier used to transmit the PSS and SSS.

11. The method of claim 1, wherein the SIB1 is transmitted using a different carrier than the first carrier used to transmit the BCH.

12. The method of claim 1, wherein at least one of a narrowband carrier location relative to the PSS carrier location or a subframe used to transmit the SIB1 is associated with the TDD frame structure determined for the narrowband communication.

13. An apparatus for wireless communication of a base station, comprising:

means for determining a time division duplex, TDD, frame structure and a TDD frame structure configuration for narrowband communication from a set of TDD frame structures having different downlink and uplink subframe configurations;

means for determining one or more narrowband carriers and subframes within the one or more narrowband carriers based on the TDD frame structure configuration to transmit at least one of a Broadcast Channel (BCH) or a system information block 1 (SIB) 1; and

means for transmitting a Primary Synchronization Signal (PSS), a Secondary Synchronization Signal (SSS), and the at least one of the BCH or the SIB1 using the TDD frame structure determined for the narrowband communication, wherein a first carrier is used for transmitting the at least one of the BCH or the SIB1, the first carrier being different from a second carrier used for transmitting one or more of the PSS or the SSS.

14. The apparatus of claim 13, wherein a narrowband carrier used for transmitting the BCH is different from a narrowband carrier used for transmitting one or more of the PSS or the SSS.

15. The apparatus of claim 13, wherein the BCH is transmitted using one or more subframes in each radio frame.

16. The apparatus of claim 13, wherein:

the SSS is transmitted using a specific subframe in every other frame; and

17. The apparatus of claim 13, wherein a periodicity associated with the transmitting the BCH indicates that the TDD frame structure is used for the narrowband communication.

18. The apparatus of claim 13, wherein at least one of a periodicity associated with the transmitting the BCH, a time location associated with the transmitting the BCH, or a frequency location associated with the transmitting the BCH is related to one or more of: the TDD frame structure determined for narrowband communication, the second carrier containing the PSS or the SSS, or information sent on the PSS or the SSS.

19. The apparatus of claim 18, wherein the first carrier used to transmit the BCH is located at a fixed frequency offset with respect to the second carrier used to transmit the one or more of the PSS or the SSS.

20. The apparatus of claim 13, wherein the BCH indicates at least one of: the TDD frame structure configuration determined for the narrowband communication, or a carrier location or subframe location associated with the SIB 1.

21. The apparatus of claim 20, wherein the information is included in the BCH by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits.

22. The apparatus of claim 13, wherein the first carrier is used to transmit both the BCH and the SIB1 when the first carrier is different from the second carrier used to transmit the PSS and SSS.

23. The apparatus of claim 13, wherein the SIB1 is transmitted using a different carrier than the first carrier used to transmit the BCH.

24. The apparatus of claim 13, wherein at least one of a narrowband carrier location relative to the PSS carrier location or a subframe used to transmit the SIB1 is associated with the TDD frame structure determined for the narrowband communication.

25. An apparatus for wireless communication of a base station, comprising:

a memory; and

at least one processor coupled to the memory and configured to:

26. The apparatus of claim 25, wherein a narrowband carrier used for transmitting the BCH is different from a narrowband carrier used for transmitting one or more of the PSS or the SSS.

27. The apparatus of claim 25, wherein the BCH is transmitted using one or more subframes in each radio frame.

28. The apparatus of claim 25, wherein:

the SSS is transmitted using a specific subframe in every other frame; and

29. The apparatus of claim 25, wherein a periodicity associated with the transmitting the BCH indicates that the TDD frame structure is used for the narrowband communication.

30. The apparatus of claim 25, wherein at least one of a periodicity associated with the transmitting the BCH, a time location associated with the transmitting the BCH, or a frequency location associated with the transmitting the BCH is related to one or more of: the TDD frame structure determined for narrowband communication, the second carrier containing the PSS or the SSS, or information sent on the PSS or the SSS.

31. The apparatus of claim 30, wherein the first carrier used to transmit the BCH is located at a fixed frequency offset with respect to the second carrier used to transmit the one or more of the PSS or the SSS.

32. The apparatus of claim 25, wherein the BCH indicates at least one of: the TDD frame structure configuration determined for the narrowband communication, or a carrier location or subframe location associated with the SIB 1.

33. The apparatus of claim 32, wherein the information is included in the BCH by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits.

34. The apparatus of claim 25, wherein the first carrier is used to transmit both the BCH and the SIB1 when the first carrier is different from the second carrier used to transmit the PSS and SSS.

35. The apparatus of claim 25, wherein the SIB1 is transmitted using a different carrier than the first carrier used to transmit the BCH.

36. The apparatus of claim 25, wherein at least one of a narrowband carrier location relative to the PSS carrier location or a subframe used to transmit the SIB1 is associated with the TDD frame structure determined for the narrowband communication.

37. A non-transitory computer-readable medium storing computer executable code for a base station, comprising code to:

38. The non-transitory computer-readable medium of claim 37, wherein a narrowband carrier used to transmit the BCH is different from a narrowband carrier used to transmit one or more of the PSS or the SSS.

39. The non-transitory computer-readable medium of claim 37, wherein the BCH is transmitted using one or more subframes in each radio frame.

40. The non-transitory computer-readable medium of claim 37, wherein:

the SSS is transmitted using a specific subframe in every other frame; and

41. The non-transitory computer-readable medium of claim 37, wherein a periodicity associated with the transmitting the BCH indicates that the TDD frame structure is used for the narrowband communication.

42. The non-transitory computer-readable medium of claim 37, wherein at least one of a periodicity associated with the transmitting the BCH, a time location associated with the transmitting the BCH, or a frequency location associated with the transmitting the BCH is related to one or more of: the TDD frame structure determined for narrowband communication, the second carrier containing the PSS or the SSS, or information sent on the PSS or the SSS.

43. The non-transitory computer-readable medium of claim 42, wherein the first carrier used to transmit the BCH is located at a fixed frequency offset with respect to the second carrier used to transmit the one or more of the PSS or SSS.

44. The non-transitory computer-readable medium of claim 37, wherein the BCH indicates at least one of: the TDD frame structure configuration determined for the narrowband communication, or a carrier location or subframe location associated with the SIB 1.

45. The non-transitory computer-readable medium of claim 44, wherein the information is included in the BCH by at least one of: including additional bits in the payload, by using a different CRC mask based on the additional bits, or by using a different scrambling code based on the additional bits.

46. The non-transitory computer-readable medium of claim 37, wherein the first carrier is used to transmit both the BCH and the SIB1 when the first carrier is different from the second carrier used to transmit the PSS and the SSS.

47. The non-transitory computer-readable medium of claim 37, wherein the SIB1 is transmitted using a different carrier than the first carrier used to transmit the BCH.

48. The non-transitory computer-readable medium of claim 37, wherein at least one of a narrowband carrier location relative to the PSS carrier location or a subframe used to transmit the SIB1 is associated with the TDD frame structure determined for the narrowband communication.