HK1173305B - Multiple carrier indication and downlink control information interaction - Google Patents

Description

Multi-carrier indication and downlink control information interaction

This application claims priority to U.S. provisional patent application No.61/241,816 entitled "multiple carrier INDICATION AND download CONTROL information interaction" filed on 9, 11, 2009, which is hereby incorporated by reference in its entirety. This application claims priority to U.S. provisional patent application No.61/248,816 entitled "download CONTROL INFORMATION formation for CARRIER OPERATION", filed 10/5/2009, and is hereby incorporated by reference in its entirety.

Technical Field

The present disclosure relates generally to the field of wireless communications, and more specifically to improving the ability of a wireless communication system to provide control information in a multi-carrier environment.

Background

This section is intended to provide a background or context to the disclosed embodiments. This description may include concepts that could be pursued, but are not necessarily ones that have been previously conceived or pursued. Thus, unless otherwise indicated herein, what is described in this section is not prior art to the claims in this application and is not admitted to be prior art by inclusion in this section.

Wireless communication systems have been widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication for multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include Code Division Multiple Access (CDMA) systems, Time Division Multiple Access (TDMA) systems, Frequency Division Multiple Access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and Orthogonal Frequency Division Multiple Access (OFDMA) systems.

Generally, a wireless multiple-access communication system is capable of supporting communication for multiple wireless terminals simultaneously. Each terminal or User Equipment (UE) communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the user equipment, and the reverse link (or uplink) refers to the communication link from the user equipment to the base stations.

Disclosure of Invention

The disclosed embodiments relate to systems, methods, apparatuses, and computer program products that facilitate interaction of multi-carrier indicators and downlink control information in a wireless communication system.

In one aspect of the disclosed embodiment, a method comprises: a plurality of component carriers configured for a wireless communication device are received, wherein the plurality of component carriers include a plurality of search spaces having one or more common search spaces and a plurality of user-specific search spaces. The method further comprises the following steps: receiving a cross-carrier (cross carrier) indicator, wherein the cross-carrier indicator is configured to enable cross-carrier signaling for a first component carrier. The method further comprises the following steps: determining whether the cross-carrier indicator exists in a control information format carried on a second component carrier according to an association of the control information format with a search space on the second component carrier.

In one embodiment, the common search space includes two Downlink Control Information (DCI) formats without a carrier indicator, and the plurality of user-specific search spaces includes DCI formats of at least two different sizes with a carrier indicator, wherein cross-carrier control is enabled for unicast traffic and not for broadcast traffic by the carrier indicator.

In one embodiment, the common search space includes DCI formats of a first size with a carrier indicator and DCI formats of a second size without a carrier indicator, and the plurality of user-specific search spaces includes DCI formats of at least two different sizes with carrier indicators, wherein cross-carrier control is enabled for unicast traffic and not for broadcast traffic by the carrier indicator.

In one embodiment, the common search space includes DCI formats of two different sizes with carrier indicators, and the plurality of user-specific search spaces includes DCI formats of at least two different sizes with carrier indicators, wherein cross-carrier control is enabled for unicast traffic and broadcast traffic by the carrier indicators.

In one embodiment, the common search space includes DCI formats of a first size with a carrier indicator and DCI formats of a second size without a carrier indicator, and the plurality of user-specific search spaces includes two DCI formats with a carrier indicator, wherein cross-carrier control is enabled for unicast traffic and broadcast traffic by the carrier indicator.

In one embodiment, the common search space includes DCI formats of three different sizes including DCI formats of two sizes with carrier indicators and DCI formats of a third size without carrier indicators, and the plurality of user-specific search spaces includes DCI formats of at least two different sizes with carrier indicators, wherein backward compatibility with LTE release 8 broadcast traffic and unicast traffic is provided.

In one embodiment, the common search space includes four different sizes of DCI formats including a first two sizes of DCI formats with carrier indicators and a second two sizes of DCI formats without carrier indicators, and the plurality of user-specific search spaces includes at least two different sizes of DCI formats with carrier indicators, wherein backward compatibility with LTE release 8 broadcast traffic and unicast traffic is provided.

In one disclosed embodiment, a method in a wireless communication system includes: formatting control information in a control channel of a communication carrier using a cross-carrier control indicator; and scrambling the CRC of the control information with a scrambling code, wherein the scrambling code is selected according to a format of the control information and a position of the control information within a plurality of search spaces in the control channel.

In another aspect, a first plurality of control information formats is associated with a first scrambling code and the at least one common search space; and a second plurality of control information formats comprising the first plurality of control information formats is associated with a second scrambling code and the plurality of user-specific search spaces, wherein the second scrambling code is different from the first scrambling code.

In another disclosed embodiment, a method in a wireless communication device includes: searching a plurality of search spaces in a control channel of a communication carrier for scrambled control information; blind decoding the plurality of search spaces using a plurality of descrambling codes to extract the control information; and determining the presence of a cross-carrier control indicator according to a format of the control information and a location of the control information in the plurality of search spaces.

In another aspect, a first plurality of control information formats is associated with a first descrambling code and at least one common search space; and a second plurality of control information formats comprising the first plurality of control information formats is associated with a second descrambling code and the plurality of user-specific search spaces, wherein the second descrambling code is different from the first descrambling code.

Other disclosed embodiments include apparatus and computer program products for performing the disclosed methods.

Drawings

Various disclosed embodiments are illustrated by way of example, and not by way of limitation, by reference to the accompanying drawings, in which:

fig. 1 illustrates a wireless communication system;

FIG. 2 shows a block diagram of a communication system;

FIG. 3 illustrates an exemplary search space;

FIG. 4 illustrates an exemplary set of aggregation levels associated with a search space;

FIG. 5 illustrates another exemplary set of aggregation levels associated with a search space;

FIG. 6 illustrates a system in which various embodiments may be implemented;

fig. 7 shows a block diagram of a wireless communication system for cross-carrier signaling;

FIG. 8A is a flow chart illustrating a method according to an exemplary embodiment;

FIG. 8B is a flowchart illustrating a method according to another example embodiment;

FIG. 8C is a flowchart illustrating a method according to yet another example embodiment;

FIG. 9 illustrates a system in which various embodiments may be implemented; and is

Fig. 10 illustrates an apparatus in which various embodiments may be implemented.

Detailed Description

In the following description, for purposes of explanation and not limitation, details and descriptions are set forth in order to provide a thorough understanding of the various disclosed embodiments. However, it will be apparent to one skilled in the art that the various embodiments may be practiced in other embodiments that depart from these details and descriptions.

As used in this application, the terms "component," "module," "system," and the like are intended to refer to a computer-related entity, either hardware, firmware, a combination of hardware and software, or software in execution. For example, a component may be, but is not limited to being: a process running on a processor, an object, an executable, a thread of execution, a program, and/or a computer. By way of example, both an application running on a computing device and the computing device can be a component. One or more components can reside within a process and/or thread of execution and a component can be localized on one computer and/or distributed between two or more computers. In addition, these components can execute from various computer readable media having various data structures thereon. The components may communicate by way of local and/or remote processes such as in accordance with a signal having one or more data packets (e.g., data from one component interacting with another component in a local system, distributed system, and/or across a network such as the internet with other systems by way of the signal).

Furthermore, certain embodiments are described herein in connection with user equipment. The user equipment may also be referred to as a user terminal and may include some or all of the functionality of a system, subscriber unit, subscriber station, mobile radio terminal, mobile device, node, device, remote station, remote terminal, wireless communication device, wireless communication apparatus, or user agent. The user equipment may be a cellular telephone, a cordless telephone, a Session Initiation Protocol (SIP) phone, a smart phone, a Wireless Local Loop (WLL) station, a Personal Digital Assistant (PDA), a laptop computer, a handheld communication device, a handheld computing device, a satellite radio, a wireless modem card, and/or other processing device for communicating over a wireless system. Various aspects are described herein in connection with a base station. A base station, which may also be referred to as an access point, node B, evolved node B (enb), or some other network entity, and may include some or all of the functionality of the above network entities, may be used to communicate with one or more wireless terminals. The base stations may communicate with the wireless terminals over the air interface. The communication may be through one or more sectors. The base station may act as a router between the wireless terminal and the rest of the access network, including an Internet Protocol (IP) network, by converting received air-interface frames to IP packets. The base station may also coordinate the management of attributes for the air interface and may also be a gateway between a wired network and a wireless network.

This application is intended to present various aspects, embodiments or features around a system that may include a number of devices, components, modules, and the like. It is to be understood and appreciated that the various systems may include additional devices, components, modules, etc. and/or may not include all of the devices, components, modules etc. discussed in connection with the figures. Furthermore, a combination of these schemes may also be used.

Also, in the present disclosure, the word "exemplary" is used to mean serving as an example, instance, or illustration. Any embodiment or design described herein as "exemplary" is not necessarily to be construed as preferred or advantageous over other embodiments or designs. Rather, the use of the exemplary words is intended to present concepts in a concrete fashion.

The various disclosed embodiments may be incorporated into a communication system. In one example, the communication system uses Orthogonal Frequency Division Multiplexing (OFDM), wherein OFDM effectively partitions the overall system bandwidth into multiple (N)_FMultiple) subcarriers, which are also referred to as frequency subchannels, tones, or bins. For an OFDM system, data to be transmitted (i.e., information bits) is first encoded using a particular coding scheme to generate coded bits, the coded bits are further combined into multi-bit symbols, and the multi-bit symbols are then mapped to modulation symbols. Each modulation symbol corresponds to a point in a signal constellation defined by a particular modulation scheme (e.g., M-PSK or M-QAM) used for data transmission. At the moment of decidingAt each time interval of each frequency subcarrier bandwidth, may be at N_FModulation symbols are transmitted on each of the frequency subcarriers. Thus, OFDM may be used to combat inter-symbol interference (ISI) caused by frequency selective fading, which is characterized by different amounts of attenuation in the system bandwidth.

Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. Such communication links may be established by single-input single-output, multiple-input single-output, or multiple-input multiple-output (MIMO) systems.

MIMO system using multi-pair (N)_TSub) transmitting antenna and multi-pair (N)_RAnd) a receiving antenna for data transmission. From N_TA secondary transmitting antenna and N_RThe MIMO channel formed by the sub-receiving antennas can be decomposed into N_SIndividual channels, which may also be referred to as spatial channels, where N_S≤min{N_T，N_R}。N_SEach of the individual channels corresponds to a dimension. The MIMO system can improve performance (e.g., higher throughput and/or higher reliability) if the other dimensionalities created by the multiple transmit and receive antennas are utilized. MIMO systems also support Time Division Duplex (TDD) and Frequency Division Duplex (FDD) systems. In a TDD system, forward and reverse link transmissions are on the same frequency range, enabling the reciprocity principle to estimate the forward link channel from the reverse link channel. This enables the base station to extract transmit beamforming gain on the forward link when multiple antennas are available at the base station.

Fig. 1 illustrates a wireless communication system in which various disclosed embodiments may be implemented. Base station 100 may include multiple antenna groups, and each antenna group may include one or more antennas. For example, if the base station 100 includes six antennas, one antenna group can include the first antenna 104 and the second antenna 106, another antenna group can include the third antenna 108 and the fourth antenna 110, and a third group can include the fifth antenna 112 and the sixth antenna 114. It should be noted that although each of the antenna groups above is identified as having two antennas, more or fewer antennas may be utilized in each antenna group.

Referring back to fig. 1, the first user equipment 116 is shown in communication with, for example, the fifth antenna 112 and the sixth antenna 114 to enable transmission of information to the first user equipment 116 over the first forward link 120 and reception of information from the first user equipment 116 over the first reverse link 118. Fig. 1 also shows a second user equipment 122, the second user equipment 122 in communication with, for example, the third antenna 108 and the fourth antenna 110 to enable transmission of information to the second user equipment 122 over a second forward link 126 and reception of information from the second user equipment 122 over a second reverse link 124. In a Frequency Division Duplex (FDD) system, communication links 118, 120, 124, 126 shown in fig. 1 can use different frequency for communication. For example, the first forward link 120 may use a different frequency than that used by the first reverse link 118.

In some embodiments, each antenna group and/or the area in which they are designed to communicate is often referred to as a sector of the base station. For example, the different antenna groups illustrated in fig. 1 may be designed to communicate to user devices in a sector of the base station 100. In communication over forward links 120 and 126, the transmitting antennas of base station 100 use beamforming to improve the signal-to-noise ratio of forward links for the different user devices 116 and 122. Moreover, a base station using beamforming to transmit to user devices scattered randomly through its coverage causes less interference to user devices in neighboring cells than a base station transmitting omni-directionally through a single antenna to all its user devices.

A communication network that may accommodate some of the various disclosed embodiments may include logical channels, wherein the logical channels are classified into control channels and traffic channels. The logical control channels may include: a Broadcast Control Channel (BCCH), which is a downlink channel for broadcasting system control information; a Paging Control Channel (PCCH), which is a downlink channel transmitting paging information; multicast Control Channel (MCCH), which is a point-to-multipoint downlink channel used to transmit Multimedia Broadcast and Multicast Service (MBMS) scheduling and control information for one or several Multicast Traffic Channels (MTCHs). Generally, after establishing a Radio Resource Control (RRC) connection, the MCCH is only used by user equipments receiving the MBMS. Dedicated Control Channel (DCCH) is another logical control channel that is a point-to-point bi-directional channel that transmits dedicated control information, such as user-specific control information used by user equipment having an RRC connection. In addition, a Common Control Channel (CCCH), which is also a logical control channel, may be used for random access information. Logical traffic channels can include a Dedicated Traffic Channel (DTCH), which is a point-to-point bi-directional channel dedicated to one user equipment for user information transfer. In addition, a Multicast Traffic Channel (MTCH) may be used for point-to-multipoint downlink transmission of traffic data.

A communication network adapted to some of the various embodiments may further comprise a logical transport channel divided into a Downlink (DL) and an Uplink (UL). DL transport channels may include a Broadcast Channel (BCH), a downlink shared data channel (DL-SDCH), a Multicast Channel (MCH), and a Paging Channel (PCH). The UL transport channels may include a Random Access Channel (RACH), a request channel (REQCH), an uplink shared data channel (UL-SDCH), and a plurality of physical channels. The physical channels may also include a set of downlink channels and uplink channels.

In some disclosed embodiments, the downlink physical channel may include at least one of: common pilot channel (CPICH), Synchronization Channel (SCH), Common Control Channel (CCCH), Shared Downlink Control Channel (SDCCH), Multicast Control Channel (MCCH), Shared Uplink Assignment Channel (SUACH), acknowledgement channel (ACKCH), downlink physical shared data channel (DL-PSDCH), Uplink Power Control Channel (UPCCH), Paging Indicator Channel (PICH), Load Indicator Channel (LICH), Physical Broadcast Channel (PBCH), Physical Control Format Indicator Channel (PCFICH), Physical Downlink Control Channel (PDCCH), physical hybrid ARQ indicator channel (PHICH), Physical Downlink Shared Channel (PDSCH), and Physical Multicast Channel (PMCH). The uplink physical channel may include at least one of: a Physical Random Access Channel (PRACH), a Channel Quality Indicator Channel (CQICH), an acknowledgement channel (ACKCH), an Antenna Subset Indicator Channel (ASICH), a shared request channel (SREQCH), an uplink physical shared data channel (UL-PSDCH), a broadband pilot channel (BPICH), a Physical Uplink Control Channel (PUCCH), and a Physical Uplink Shared Channel (PUSCH).

Furthermore, the following terms and features may be used to describe various disclosed embodiments:

third generation 3G

3GPP third generation partnership project

ACLR adjacent channel leakage ratio

ACPR adjacent channel power ratio

ACS adjacent channel selectivity

ADS advanced design system

AMC adaptive modulation coding

Additional maximum power reduction (A-MPR)

ARQ automatic repeat request

BCCH broadcast control channel

BTS base transceiver station

CDD cyclic delay diversity

CCDF complementary cumulative distribution function

CDMA code division multiple access

CFI control format indicator

Co-MIMO cooperative MIMO

CP Cyclic Prefix

CPICH common pilot channel

Common public radio interface for CPRI

CQI channel quality indicator

CRC cyclic redundancy check

DCI downlink control indicator

DFT discrete Fourier transform

DFT-SOFDM discrete Fourier transform spread OFDM

DL Downlink (base station to user transmission)

DL-SCH Downlink shared channel

DSP digital signal processing

DT development toolset

DVSA digital vector signal analysis

EDA electronic design automation

E-DCH enhanced dedicated channel

E-UTRAN evolved UMTS terrestrial radio access network

eMBMS evolved multimedia broadcast multicast service

eNB evolved node B

EPC evolved packet core network

Energy per resource unit of EPRE

ETSI European Telecommunications standards institute

E-UTRA evolved UTRA

E-UTRAN evolved UTRAN

EVM error vector magnitude

FDD frequency division duplex

FFT fast Fourier transform

FRC fixed reference channel

FS1 frame structure type 1

FS2 frame structure type 2

GSM global mobile communication system

HARQ hybrid automatic repeat request

HDL hardware description language

HI HARQ indicator

HSDPA high speed downlink packet access

HSPA high speed packet access

HSUPA high speed uplink packet access

Inverse FFT IFFT

IOT interoperability test

IP internet protocol

LO local oscillator

LTE Long term evolution

MAC medium access control

MBMS multimedia broadcast multicast service

Multicast/broadcast over MBSFN single frequency network

MCH multicast channel

MIMO multiple input multiple output

MISO multiple input single output

MME mobility management entity

Maximum output power of MOP

MPR maximum power reduction

MU-MIMO multiuser MIMO

NAS non-access stratum

OBSAI open base station architecture interface

OFDM orthogonal frequency division multiplexing

OFDMA orthogonal frequency division multiple access

PAPR peak-to-average power ratio

PAR peak-to-average ratio

PBCH physical broadcast channel

P-CCPCH primary common control physical channel

PCFICH physical control Format indicator channel

PCH paging channel

PDCCH physical downlink control channel

PDCP packet data convergence protocol

PDSCH physical downlink shared channel

PHICH physical hybrid ARQ indicator channel

PHY physical layer

Physical Random Access Channel (PRACH)

PMCH physical multicast channel

PMI precoding matrix indicator

P-SCH Primary synchronization Signal

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

Fig. 2 illustrates a block diagram of an exemplary communication system in which various embodiments may be adapted. The MIMO communication system 200 shown in fig. 2 includes a transmitter system 210 (e.g., a base station or access point) and a receiver system 250 (e.g., an access terminal or user equipment) in the MIMO communication system 200. It will be appreciated by those skilled in the art that embodiments of these systems enable bi-directional communication even though the base station is referred to as the transmitter system 210 and the user equipment is referred to as the receiver system 250 (as described above). In this regard, the terms "transmitter system 210" and "receiver system 250" should not be used to denote uni-directional communication from either system. It should also be noted that transmitter system 210 and receiver system 250 of fig. 2 are each capable of communicating with a number of other receiver systems and transmitter systems not explicitly shown in fig. 2. At the transmitter system 210, traffic data for a number of data streams is provided from a data source 212 to Transmit (TX) data processor 214. Each data stream may be transmitted by a respective transmitter system. TX data processor 214 formats, codes, and interleaves the traffic data for each data stream based on a particular coding scheme selected for that data stream to provide coded data.

The coded data for each data stream may be multiplexed with pilot data using, for example, OFDM techniques. Typically, the pilot data is a known data pattern that is processed in a known manner and may be used at the receiver system to estimate the channel response. The multiplexed pilot and coded data for each data stream can then be modulated (symbol mapped) based on a particular modulation scheme (e.g., BPSK, QPSK, M-PSK, or M-QAM) selected for that data stream to provide modulation symbols. The data rate, coding, and modulation for each data stream may be determined by instructions performed by processor 230 of transmitter system 210.

In the exemplary block diagram of fig. 2, the modulation symbols for all data streams can be provided to a TX MIMO processor 220, and the TX MIMO processor 220 can further process the modulation symbols (e.g., for OFDM). Then, TX MIMO processor 220 forwards to N_TA plurality of transmitter system transceivers (TMTR)222a through 222t provide N_TA stream of modulation symbols. In one embodiment, TX MIMO processor 220 can also apply beamforming weights to the symbols of the data streams and to the antenna from which the symbol is being transmitted.

Each transmitter system transceiver 222a through 222t receives and processes a respective symbol stream to provide one or more analog signals, and further conditions the analog signals to provide a modulated signal suitable for transmission over the MIMO channel. In some embodiments, the conditioning may include, but is not limited to, operations such as amplification, filtering, up-conversion, and the like. The modulated signals generated by transmitter system transceivers 222a through 222t are then transmitted from transmitter system antennas 224a through 224t shown in fig. 2.

At receiver system 250, the transmitted modulated signals may be received by receiver system antennas 252a through 252r and the received signals from each of the receiver system antennas 252a through 252r are provided to a respective receiver system transceiver (RCVR)254a through 254 r. Each receiver system transceiver 254a through 254r conditions a respective received signal, digitizes the conditioned signal to provide samples, and may further process the samples to provide a corresponding "received" symbol stream. In some embodiments, the conditioning may include, but is not limited to, operations such as amplification, filtering, down-conversion, and the like.

The RX data processor 260 then receives and processes the symbol streams from the receiver system transceivers 254a through 254r in accordance with a particular receiver processing technique to provide a plurality of "detected" symbol streams. In one embodiment, each detected symbol stream may include symbols that are estimates of the symbols transmitted for the respective data stream. RX data processor 260 then at least partially demodulates, deinterleaves, and decodes each detected symbol stream to recover the traffic data for the corresponding data stream. The processing by RX data processor 260 may be complementary to that performed by TX MIMO processor 220 and TX data processor 214 at transmitter system 210. RX data processor 260 may further provide processed symbol streams to a data sink 264.

In some embodiments, the channel response estimate is generated by RX data processor 260 and may be used to perform space/time processing at receiver system 250, adjust power levels, change modulation rates or schemes, and/or other appropriate actions. RX data processor 260 may further estimate channel characteristics such as the signal-to-noise ratio (SNR) and signal-to-interference ratio (SIR) of the detected symbol streams. RX data processor 260 may then provide estimated channel characteristics to a processor 270. RX data processor 260 and/or processor 270 of receiver system 250 may further derive an estimate of the "operating" SNR for the system, for example. Processor 270 of receiver system 250 can also provide Channel State Information (CSI), which can comprise information regarding the communication link and/or the received data stream. This information, which may include, for example, SNR and other channel information of operation, may be used by the transmitter system 210 (e.g., a base station or an evolved node B) to make appropriate decisions regarding, for example, user equipment scheduling, MIMO settings, modulation and coding selection, etc. At receiver system 250, the CSI generated by processor 270 is processed by a TX data processor 238, modulated by a modulator 280, conditioned by receiver system transceivers 254a through 254r, and transmitted back to transmitter system 210. In addition, a data source 236 at receiver system 250 can provide additional data for processing by TX data processor 238.

In some embodiments, processor 270 at receiver system 250 may also periodically determine which precoding matrix to use. Processor 270 formulates a reverse link message comprising a matrix index portion and a rank value portion. The reverse link message may comprise various types of information regarding the communication link and/or the received data stream. The reverse link message is then processed by a TX data processor 238 at receiver system 250, where TX data processor 238 can also receive traffic data for a number of data streams from a data source 236. The processed information is then modulated by a modulator 280, conditioned by one or more of the receiver system transceivers 254a through 254r, and transmitted back to the transmitter system 210.

In some embodiments of MIMO communication system 200, receiver system 250 is capable of receiving and processing spatially multiplexed signals. In these systems, spatial multiplexing occurs at transmitter system 210 by multiplexing and transmitting different data streams over transmitter system antennas 224a through 224 t. This is in contrast to the use of a transmit diversity scheme in which the same data stream is transmitted from multiple transmitter system antennas 224a through 224 t. In a MIMO communication system 200 capable of receiving and processing spatially multiplexed signals, a precoding matrix is typically used at the transmitter system 210 to ensure that the signals transmitted from each of the transmitter system antennas 224a through 224t are sufficiently decorrelated from one another. This decorrelation ensures that the composite signal arriving at any particular receiver system antenna 252a through 252r can be received and that the individual data streams can be determined in the presence of signals carrying other data streams from other transmitter system antennas 224a through 224 t.

Since the cross-correlation between streams may be affected by the environment, it is advantageous for receiver system 250 to feed back information about the received signal to transmitter system 210. In these systems, transmitter system 210 and receiver system 250 each include a codebook having a plurality of precoding matrices. In some instances, each of these precoding matrices may be related to a cross-correlation experienced in the received signal. Since it is advantageous to transmit the index of a particular matrix rather than the values in that matrix, the feedback control signal transmitted from receiver system 250 to transmitter system 210 typically includes the index of a particular precoding matrix. In some examples, the feedback control signal also includes a rank index, where the rank index indicates to the transmitter system 210 how many independent data streams to use for spatial multiplexing.

Other embodiments of the MIMO communication system 200 are configured to use a transmit diversity scheme instead of the spatial multiplexing scheme described above. In these embodiments, the same data stream is transmitted over transmitter system antennas 224a through 224 t. In these embodiments, the data rate transmitted to receiver system 250 is generally lower than for spatial multiplexing MIMO communication system 200. These embodiments provide robustness and reliability of the communication channel. In a transmit diversity system, each of the signals transmitted from the transmitter system antennas 224a through 224t will experience a different interference environment (e.g., fading, reflections, multipath phase shifts). In these embodiments, the different signal characteristics received at the receiver system antennas 252a through 252t may be used to determine the appropriate data streams. In these embodiments, the rank indicator is typically set to 1, telling the transmitter system 210 not to use spatial multiplexing.

Other embodiments may use a combination of spatial multiplexing and transmit diversity. For example, in a MIMO communication system 200 using four transmitter system antennas 224a through 224t, a first data stream may be transmitted over two transmitter system antennas 224a through 224t and a second data stream may be transmitted over the remaining two transmitter system antennas 224a through 224 t. In these embodiments, the rank index is set to an integer less than the full rank of the precoding matrix, thereby instructing the transmitter system 210 to use a combination of spatial multiplexing and transmit diversity.

At transmitter system 210, the modulated signals from receiver system 250 are received by transmitter system antennas 224a through 224t, conditioned by transmitter system transceivers 222a through 222t, demodulated by a transmitter system demodulator 240, and processed by a RX data processor 242 to extract the reserve link message transmitted by receiver system 250. In some embodiments, processor 230 of transmitter system 210 then determines which precoding matrix to use for future forward link transmissions and then processes the extracted message. In other embodiments, processor 230 uses the received signals to adjust the beamforming weights for future forward link transmissions.

In other embodiments, the reported CSI can be provided to processor 230 of transmitter system 210 and used to determine, for example, data rates, as well as coding and modulation schemes to be used for one or more data streams. The determined coding and modulation schemes can then be provided to one or more transmitter system transceivers 222a through 222t at transmitter system 210 for quantization and/or use in later transmissions to receiver system 250. Additionally and/or alternatively, the processor 230 of the transmitter system 210 can use the reported CSI to generate various controls for the TX data processor 214 and the TX mimo processor 220. For example, CSI and/or other information processed by RX data processor 242 of transmitter system 210 can be provided to a data sink 244.

In some embodiments, processor 230 at transmitter system 210 and processor 270 at receiver system 250 may direct the operation of their respective systems. Additionally, memory 232 at transmitter system 210 and memory 272 at receiver system 250 may store program codes and data used by transmitter system processor 230 and receiver system processor 270, respectively. In addition, in the receiver systemAt 250, N can be processed using various processing techniques_RA received signal to detect N_TA transmitted symbol stream. These receiver processing techniques may include spatial and space-time receiver processing techniques (which may include equalization techniques), "successive nulling/equalization and interference cancellation" receiver processing techniques, and/or "successive interference cancellation" or "successive cancellation" receiver processing techniques.

In LTE systems, the Physical Downlink Shared Channel (PDSCH) carries data and signaling information destined for user equipment; while the Physical Downlink Control Channel (PDCCH) carries a message called Downlink Control Information (DCI). The DCI includes information on downlink scheduling assignment, uplink resource grant, transmission scheme, uplink power control, hybrid automatic return retransmission request (HARQ) information, Modulation and Coding Scheme (MCS), and other information. The DCI may be UE-specific (dedicated) or cell-specific (common), and the DCI is placed in different dedicated search spaces and common search spaces within the PDCCH according to the format of the DCI. The user equipment attempts to decode the DCI by performing a process called blind decoding during which multiple decoding attempts are performed in the search space until the DCI is detected.

The size of a DCI message may vary depending on the type and amount of information carried by the DCI. For example, if spatial multiplexing is supported, the size of the DCI message is larger than the case of consecutive frequency allocation. Similarly, for systems using MIMO, the DCI must include additional signaling information that is not needed by systems that do not use MIMO. Thus, the DCI is classified into different formats suitable for different configurations. Table 1 summarizes the DCI formats listed as part of the LTE release 8 specification. It should be noted that the disclosed embodiments may also be implemented in connection with other DCI formats and/or sizes.

Table 1-exemplary DCI formats

The size of the DCI format depends not only on the amount of information carried in the DCI message, but also on other factors such as the transmission bandwidth, the number of antenna ports, the TDD or FDD mode of operation, etc. For example, the exemplary sizes of the different DCI formats listed in table 1 are associated with a system bandwidth of 50 resource blocks, FDD, and four antennas at the evolved node B, corresponding to a 10MHz bandwidth.

To simplify the decoding of DCI messages at user equipment, the LTE release 8 specification also requires that DCI format 0 (for uplink grants) and format 1A (for downlink resource allocations) always have the same size. However, due to the different information fields in DCI format 0 and DCI format 1A, and due to, for example, bandwidth differences between uplink and downlink channels, the sizes of the format 0DCI message and the format 1A DCI message may be different. Thus, in the case where DCI format 0 and DCI format 1A have different sizes, the smaller of the two is padded with zeros to produce the same DCI message size. To distinguish between format 0DCI messages and format 1A DCI messages, a single bit is provided in both formats that signals the presence of format 0 or format 1A.

It should be noted that in some systems, the DCI message is also appended with Cyclic Redundancy Check (CRC) bits for error detection. The encoded DCI bits are then mapped to Control Channel Elements (CCEs) according to the DCI format. The PDCCH may carry DCI messages associated with multiple user equipments. Therefore, a particular user equipment must be able to identify the DCI message intended for that particular user equipment. To this end, the user equipment is assigned certain identifiers (e.g., cell radio network temporary identifier (C-RNTI)) that facilitate detection of DCI associated with the user equipment. To reduce signaling overhead, the CRC bits appended to each DCI payload are scrambled (e.g., masked) using an identifier associated with a particular user device (e.g., C-RNTI) and/or an identifier associated with a group of user devices. In an operation known as "blind decoding," the user equipment may use its unique identifier to descramble (or demask) all potential DCI messages and perform a CRC check on the DCI payload. If the CRC check passes, then the contents of the control channel are declared valid for the user equipment, which may then process the DCI.

To reduce power consumption and overhead at the user equipment, a limited set of Control Channel Element (CCE) locations may be specified, where the set of CCE locations includes locations where DCI payloads associated with a particular UE may be placed. In LTE release 8, a CCE consists of nine logically contiguous Resource Element Groups (REGs), where each REG includes 4 Resource Elements (REs). Each RE is a frequency-time unit. CCEs may be aggregated at different levels (e.g., 1, 2, 4, and 8) depending on DCI format and system bandwidth. The set of CCE locations where the user equipment is able to find its corresponding DCI message may be considered a search space. The search space may be divided into two regions: a common CCE region or search space; and UE-specific (dedicated) CCE regions or search spaces. The common CCE region is monitored by all UEs served by the enode B and may include information such as paging information, system information, random access procedures, and the like. The UE-specific CCE region includes user-specific control information and is configured separately for each user equipment.

Fig. 3 shows an exemplary search space 300 on PDCCH 302, where the search space 300 is divided into a common search space 304 and a UE-specific search space 306. It should be noted that while the exemplary search space 302 of fig. 3 is shown as a set of 32 logically contiguous CCE blocks for simplicity, it should be understood that the disclosed embodiments may be implemented using a different number of CCEs. Each CCE includes a fixed number of resource elements located at discrete locations. Alternatively, the CCEs may be arranged in non-contiguous locations within a resource block of one or more downlink control channels. Further, the common search space 304 and the UE-specific search space 306 may span overlapping CCEs. CCEs are consecutively numbered. The common search space always starts from CCE 0, while the UE-specific search space has a starting CCE index that depends on the UE ID (e.g., C-RNTI), subframe index, CCE aggregation level, and other random origins.

In the LTE rel-8 system, the number of CCEs (N) available for PDCCH may be determined according to the system bandwidth, the size of the control region, and the configuration of other control signals, etc. (N_CCERepresentation). The CCE set for the common search space ranges from 0 to min {16, N }_CCE-1}. For all UEs, the CCE set for the UE-specific search space ranges from 0 to N_CCE-1, which is a superset of the CCE aggregation range used for the common search space. For a particular UE, the CCE set for that UE ranges from CCE 0 to CCE N, depending on the configured identifier and other factors_CCE-1 is a subset of the entire set. In the example of FIG. 3, N_CCE＝32。

The size of the search space (e.g., search space 302 of fig. 3) or the size of a set of CCE locations may be based on an aggregation level. As previously described, the size of the DCI message may depend on the DCI format and transmission bandwidth. The aggregation level specifies the number of logically or physically consecutive CCEs used to transmit a single DCI payload. The common search space may include two possible aggregation levels: level 4 (e.g., 4 CCEs) and level 8 (e.g., 8 CCEs). In some systems, to reduce the computations that the user equipment must perform, the aggregation level 4 of the common search space may be configured to accommodate up to four DCI locations. Similarly, the aggregation level 8 of the common search space may be configured to accommodate up to 2DCI positions. Fig. 4 provides an exemplary illustration of a common search space 400 on PDCCH 402, where the common search space 400 is configured to accommodate four aggregation level 4 candidates 404 and two aggregation level 8 candidates 406. Thus, in the exemplary diagram of fig. 4, there are a total of 6 candidates in the common search space 400.

The UE-specific search space may be configured to include four aggregation levels corresponding to 1, 2, 4, and 8 CCEs, respectively: 1. 2, 4 or 8. Fig. 5 provides an exemplary illustration of a UE-specific search space 500 on PDCCH 502, where the UE-specific search space 500 may be configured to accommodate: six aggregation level 1 candidates 504, six aggregation level 2 candidates 506, two aggregation level 4 candidates 508, and two aggregation level 8 candidates 510. Thus, in the example diagram of fig. 5, there are a total of 16 candidates in the UE-specific search space 500.

It should be noted that in the example of fig. 5, the starting CCE indexes of the four aggregation levels are different and follow the so-called "tree structure" used in LTE release 8. That is, for aggregation level L, the starting CCE index is always an integer multiple of L. In each aggregation level, the search space is logically contiguous. The starting CCE index for each aggregation level may also depend on time (i.e., subframe number). In other contemplated embodiments, the starting CCE index for each aggregation level may be the same or different.

Furthermore, as previously discussed, for a given UE, the UE-specific search space is the set 0, N_CCE-1} of which N is_CCEIs the total number of available CCEs. In the example shown in FIG. 3, N_CCE32. For example, due to the "tree structure" and potentially different starting CCE indexes at different aggregation levels, in one subframe, the UE may have CCE 9 as the starting CCE index at aggregation level 1, CCE 18 as the starting CCE index at aggregation level 2, CCE 4 as the starting CCE index at aggregation level 4, and CCE 8 as the starting CCE index at aggregation level 8. Since the UE-specific search space for each aggregation level is contiguous, the 2 candidates for aggregation level 4 for that UE are CCE {4, 5, 6, 7} and CCE {8, 9, 10, 11 }. It should also be noted that the common search space 400 of fig. 4 and the UE-specific search space 500 of fig. 5 are provided to facilitate understanding of basic concepts associated with the disclosed embodiments. Thus, it should be understood that common search spaces and UE-specific search spaces with different numbers of candidate locations and different configurations of candidate locations may be configured and used in accordance with the disclosed embodiments.

Each candidate in the common search space and the UE-specific search space represents one possible DCI transmission. For example, if the DCI is for a specific user equipment, the CRC may be masked using a cell radio network temporary identifier (C-RNTI). For example, if the DCI includes paging information or system information, the CRC is masked using paging RNTI (P-RNTI) or system information RNTI (SI-RNTI). In other examples, additional RNTIs or other codes may be used to mask the CRC. As previously described, the user equipment performs blind decoding to find the location of the control information. For example, in the exemplary UE-specific search space 500 shown in fig. 5, the user equipment may make up to 16 decoding attempts to determine which, if any, of the UE-specific candidate locations 504, 506, 508, 510 includes DCI information associated with the user equipment. Additional decoding attempts may be required due to additional RNTIs, DCI formats and multiple PDCCH candidates.

In some embodiments, the number of DCI blind decodes may be limited by configuring each user equipment (e.g., by using upper layers of RRC signaling) to operate in one of several transmission modes in a semi-static manner. Table 2 provides an exemplary list of different transmission modes. It should be noted that the disclosed embodiments may also be implemented in connection with other transmission modes not listed in table 2.

Table 2-exemplary transmission modes

Transmission mode numbering	Description of the invention
		1	Single antenna Port-Port 0
2	Transmit diversity
		3	Open loop spatial multiplexing
4	Closed loop spatial multiplexing

5	Multi-user MIMO
		6	Closed-loop rank 1 precoding
7	Single antenna port-beamforming with UE-specific reference signals
		8	Single layer transmission or dual layer transmission with UE specific reference signals

In one embodiment, each transmission mode may be associated with two different sizes of downlink DCI formats, where one of the two transmission modes is always DCI format 1A. In this example, DCI formats 0 and 1A may be forced to have the same size (e.g., through zero padding, if necessary, as aboveAs described). Thus, each transmission mode has at most two associated DCI format sizes: one corresponding to format 0/1a and the other corresponding to another DCI format. Using the common search space and the user-specific search space shown in fig. 3 to 5, the maximum number of blind decodings can be calculated as: (2DCI size) x (6+16 search candidate) ═ 44. In another embodiment, to support UL MIMO, a third DCI format size may be introduced in the UE-specific search space such that the maximum number of blind decodes becomes: (2DCI size) x 6+ (3DCI size) x 16 ═ 60. It should be noted that the maximum number of decoding attempts can be generalized as: n is a radical of_DCIX (the total number of DCI sizes) x (the number of search candidates).

Table 3 provides an exemplary list of seven transmission modes and associated DCI formats. It should be noted that the list in table 3 is provided only to aid in understanding the underlying concepts. However, the disclosed embodiments are equally applicable to other transmission modes and/or DCI format configurations associated with both uplink and downlink transmissions.

Table 3-exemplary transmission modes and associated DCI formats

Transmission mode numbering	First DCI Format	Second DCI Format
			1	0 and 1A	1
2	0 and 1A	1

3	0 and 1A	2A
			4	0 and 1A	2
5	0 and 1A	1D
			6	0 and 1A	1B
7	0 and 1A	1

In the exemplary list of table 3, DCI formats 0 and 1A (which have the same size) are always selected as one of the possible DCI formats for all transmission modes. However, each transmission mode is also associated with another DCI format that may vary depending on the transmission mode. For example, DCI format 2A may be associated with transmission mode 3, DCI format 1B may be associated with transmission mode 6, and DCI format 1 may be associated with transmission modes 1, 2, and 7. The list of table 3 also shows that two or more of these transmission modes may have the same DCI format. For example, in the exemplary list of table 3, transmission modes 1, 2, and 7 are each associated with DCI format 0/1a and DCI format 1.

In a system using multiple Component Carriers (CCs), the number of decodings associated with a blind decoding scheme may increase. In some systems, multiple carriers may be used to increase the overall system bandwidth. For example, two 10MHz component carriers and four 20MHz component carriers may be aggregated to extend the bandwidth of the LTE system to 100 MHz. These component carriers may span a contiguous portion of the spectrum or may be located in a non-contiguous portion of the spectrum.

FIG. 6 illustrates a system 600 that can be used in accordance with the disclosed embodiments. System 600 can include a user equipment 610, where the user equipment 610 can be configured with one or more component carriers 1 through N (CC)₁-CC_N) Communicate with an evolved node b (enb)620 (e.g., a base station, access point, etc.). Although only one user equipment 610 and one eNB 620 are shown in fig. 6, it should be understood that system 600 may include any number of user equipments 610 and/or enbs 620. eNB 620 may transmit component carrier CC₁To CC_NThe forward (downlink) channels 632 through 642 on transmit information to the user equipment 610. In addition, the user equipment 610 may pass through the component carrier CC₁To CC_NThe reverse (uplink) channels 634 through 644 on transmit information to the eNB 620. In describing the various entities of fig. 6, as well as other figures associated with some of the disclosed embodiments, terminology associated with 3GPP LTE or LTE-a wireless networks is used for purposes of illustration. However, it should be understood that system 600 may operate in other networks such as, but not limited to: an OFDMA wireless network, a CDMA network, a 3GPP2 CDMA2000 network, and so on.

In LTE-a based systems, user equipment 610 may be configured with multiple component carriers used by eNB 620 to enable a wider overall transmission bandwidth. As shown in fig. 6, user equipment 610 may be configured with "component carrier 1" 630 through "component carrier N" 640, where N is an integer greater than or equal to one. Although fig. 6 illustrates two component carriers, it should be understood that user equipment 610 may be configured with any suitable number of component carriers and, thus, the subject matter and claims disclosed herein are not limited to two component carriers. In one example, some of the plurality of component carriers may be LTE release 8 carriers. Thus, for legacy (e.g., LTE release 8 based) user equipment, some of the component carriers may appear as LTE release 8 carriers. Component carriers 630 through 640 may include respective downlinks 632 through 642, and respective uplinks 634 through 644.

In multi-carrier operation, DCI messages associated with different user equipment may be carried on multiple component carriers. For example, DCI on a PDCCH may be included on the same component carrier configured for PDSCH transmission by the user equipment (i.e., on-carrier signaling). Alternatively or additionally, DCI may be carried on a component carrier that is different from the target component carrier for PDSCH transmission (i.e., cross-carrier signaling). For example, referring to fig. 6, a downlink assignment on "component carrier 1" 630 may be indicated to the user equipment 610 through a PDCCH on "component carrier N" 640. Cross-carrier signaling facilitates operation of heterogeneous networks in which some of the component carriers may have unreliable control information transmission due to frequency-dependent propagation and/or interference characteristics, for example, due to Time Division Multiplexing (TDM) properties of the downlink control signaling structure. Thus, in some examples, transmission that carries control information on different component carriers with less interference may be advantageous due to strong interference from neighboring cells. In other examples, some of the component carriers are not backward compatible or even capable of carrying control information. Thus, different component carriers may be used to provide control signaling.

In some embodiments, a Carrier Indicator Field (CIF), which may be semi-statically enabled, may be included in some or all DCI formats, such asPDCCH control signaling (cross-carrier signaling) is facilitated to be transmitted on a carrier different from the target carrier for PDSCH transmission. In one example, the carrier indicator field includes 1-3 bits that identify a particular component carrier in a system that uses multiple component carriers. In another example, the carrier indicator field includes a fixed 3 bits, the 3 bits identifying a particular component carrier in a system using multiple component carriers. In general, if the Carrier Indicator (CI) is UE-specific, then the value of the carrier indicator is ceiling log₂(N_UE)]To give the required number of CIF bits, where N_UEIs the number of carriers configured per UE. If the CI is cell-specific (i.e., common to all UEs in the cell), then it is ceiling log₂(M)]To give the number of bits needed to support CIF, where M is the number of carriers configured for that cell. A carrier indicator field is included as part of the DCI so that a component carrier can be linked with another component carrier.

Fig. 7 illustrates a communication system 700 in one embodiment. In fig. 7, a communication system 700 includes a node, shown as a serving evolved node b (eNB)702, that schedules and supports multi-carrier operation of an improved User Equipment (UE) 704. In some instances, the eNB 702 may also support single carrier operation for legacy UEs 706. To facilitate the improved UE 704, the serving eNB 702 encodes a Carrier Indicator (CI)708 on a first channel 710 on a first carrier 712 to schedule an allocation or grant 714 for a second channel 716 on a second carrier 718. In a first example, there are more than one uplink channel (i.e., second channel) 720 on the second carrier 718 designated by the CI 708. In a second example, there is a downlink second channel 722 on the second carrier 718 specified by the CI 708.

In an aspect, serving eNB 702 uses receiver 723, transmitter 724, computing platform 726, and encoder 728 to perform cross-carrier allocation in multicarrier wireless communications. The computing platform 726 accesses the user-specific code 730 and generates an allocation or grant 714 for one or more uplink channels 720 or downlink second channels 722 on the second carrier 718 in accordance with the CI 708. An encoder 728 encodes at least one of the common search space 734 and a user-specific search space 732 using a user-specific code 730 to provide the CI 708. The transmitter 724 transmits the first channel 710 on the first carrier 712 including the allocation or grant 714.

Similarly, improved UE 704 uses receiver 743, transmitter 744, computing platform 746, and decoder 748 to handle cross-carrier allocation in multi-carrier wireless communications. Computing platform 746 accesses user-specific code 750. The receiver 742 receives the first channel 710 on the first carrier 712. The decoder 748 decodes at least one of the common search space 734 and the user-specific search space 732 using the user-specific code 750 to detect the CI 708. The transmitter 744 or receiver 742 uses the assignment or grant 714 of the first channel 710 on the first carrier 712 according to the CI 708.

In one exemplary implementation, LTE-a supports multi-carrier operation. A UE may be configured with multiple carriers. Different carriers may experience different levels of interference. Furthermore, some carriers may not be backward compatible with legacy UE (e.g., LTE release 8) devices, and some carriers may not even carry any control signals. Thus, it may be desirable to have cross-carrier control signaling so that one carrier can send the PDCCH scheduling PDSCH transmissions over a different carrier.

One problem addressed by the system of fig. 7 relates to: an implementation of a carrier indicator field at the eNB 702, comprising: whether the CIF is applicable only to unicast services, only to broadcast services, or to both unicast and broadcast services; and the implications of the design of DCI formats for cross-carrier signaling according to some systems for which DCI format 1A is present in both common and user-specific search spaces, and which DCI format 1A may be used to schedule both unicast and broadcast traffic. Unicast traffic is point-to-point transmission between the eNB 702 and one of the UEs 704, 706. The broadcast service is a downlink-only point-to-multipoint connection between the eNB 702 and multiple UEs 704, 706.

In one embodiment (option I), the eNB 702 may signal cross-carrier operation by extending the LTE release 8DCI format with CIF bits. eNB 702 may apply CIF to DCI formats only in UE-specific search spaces, where CIF is used for both downlink DCI formats configured for specific downlink transmission modes and DCI format 0 for uplink scheduling. This may include: a new downlink DCI format (1A plus one other format) and a new DCI format 0 are defined. These new DCI formats may be labeled 1A ' (initially 1A), 1B ', 1D ', 2A ', and 0 '. Thus, for this embodiment, the common search space uses DCI formats 1A/0 and 1C, and the UE-specific search space uses new DCI formats 1A '/0' and 1B '/1D'/2 '/2A'. It should be noted that the same design may also be applicable to any other DCI format in the UE-specific search space, e.g., DCI 2B supporting dual-layer beamforming, a new DCI format supporting UL MIMO operation, etc. Other embodiments described below may also be applicable to any other DCI format in the UE-specific search space.

In this embodiment, because CIFs are not included in the common search space, the three DCI formats 1A/0 and 1C may remain unchanged (i.e., LTE release 8 compatible) and may be used for single carrier broadcast traffic, while DCI formats 1A 'and 0' may be used for cross-carrier unicast traffic. When this option does not support cross-carrier signaling for broadcast services via DCI formats, such signaling may be addressed by redesigning the System Information Block (SIB) or Master Information Block (MIB) to include information for one or more other carriers, or by dedicated layer 3(RRC) signaling.

In a variation of the first embodiment (option IA), when reserved bits in DCI format 1A are no longer needed (e.g., when the DCI is scrambled with a scrambling code based on paging RNTI (P-RNTI), system information RNTI (SI-RNTI), or random access RNTI (RA-RNTI)), the eNB 702 may reuse these reserved bits for carrier indication instead of extending the DCI format with CIF. For example, a hybrid automatic repeat request (HARQ) process number and/or a downlink allocation index (TDD only) are reserved bits in LTE release 8 that can be used to embed CIF. Thus, DCI format 1A' may be the same size as format 1A, but may still provide cross-carrier signaling for broadcast services. The same DCI format design principle (i.e., embedded CIF) may be adapted to other embodiments described below.

In another embodiment (option II), eNB 702 may apply CIF to both UE-specific search space and common search space. In this case, CIF is applied to: DCI formats 1A, 0, and 1C in a common search space; the downlink DCI format configured for a particular transmission mode in the UE-specific search space, and DCI format 0 for uplink scheduling. The relevant DCI format 1A and one other format as well as DCI format 0 are modified with CIF bits (by extension or embedding, as described above) to produce formats 1A ', 1B '/1D '/2 '/2A ', 1C ' and 0 '. Thus, the common search space will use DCI formats 1A '/0 ' and 1C ', and the UE-specific search space will use the same DCI format (1A '/0 ', 1B '/1D '/2 '/2A ') as option I above.

In contrast to option I, the option II embodiment sets the UE to have cross-carrier signaling in both the common search space and the UE-specific search space for unicast traffic and broadcast traffic. However, the option II embodiment is not backward compatible with LTE release 8, since it includes modifications to DCI formats 1A and 1C to carry broadcast traffic.

In another embodiment (option III), eNB 702 may apply CIF to both UE-specific search space and common search space, but may restrict the use of CIF to DCI format 1A/0 in the common search space (CIF does not apply to DCI format 1C). As with the option II embodiment, in the UE-specific search space, CIF may be applied to downlink DCI formats configured for specific downlink transmission modes, and DCI format 0 for uplink scheduling. The relevant DCI format 1A and one other format as well as DCI format 0 are modified with CIF bits (by extension or embedding) to produce formats 1A ', 1B'/1D '/2'/2A 'and 0'. DCI format 1C does not change. Thus, the common search space includes DCI formats 1A ' and 1C, and the DCI formats used in the UE-specific search space are the same as in the case of option I and option II (i.e., 1A '/0 ', 1B '/1D '/2 '/2A ').

In contrast to options I and II, the option III embodiment sets the UE to have cross-carrier signaling in both the common search space and the UE-specific search space for unicast traffic and broadcast traffic (using only DCI format 1A). The option III embodiment is also backward compatible with LTE release 8 by keeping DCI format 1C unchanged.

In another embodiment (option IV), the eNB 702 may apply CIF to DCI formats in both the common search space and the UE-specific search space: DCI formats 1A, 0, and 1C applied in a common search space; downlink DCI formats configured for downlink transmission mode, and DCI format 0 for uplink scheduling, applied in the UE-specific search space. For backward compatibility of broadcast traffic and/or unicast traffic, DCI formats 1A or 1C, or both 1A and 1C, may be maintained (i.e., not modified).

In particular, according to the above description of the option IV embodiment, the following exemplary alternatives may be considered for common search space blind decoding, where 2 positions are defined for CCE aggregation level 8 and 4 positions are defined for CCE aggregation level 4:

alternative 1: 3DCI sizes 1A '/0 ', 1C ', 1A → 3(4+2) ═ 18 blind decodes.

Alternative 2: the 3DCI sizes 1A '/0', 1C → 3(4+2) ═ 18 blind decodes.

Alternative 3: the 3DCI sizes 1A '/0', 1C, 1A → 3(4+2) — 18 blind decodes.

Alternative 4: the 4 DCI sizes 1A '/0 ', 1C ', 1A, 1C → 4(4+2) ═ 24 blind decodes.

For each of the four alternatives, the UE-specific search space is the same as option I and option II with 32 blind decodes. Thus, in case of option IV, 50 (18 + 32) or 56 (24 + 32) blind decodes may be required compared to 44 blind decodes in LTE release 8 to obtain flexibility in cross-carrier signaling and backward compatibility with LTE release 8 unicast traffic or broadcast traffic, or both unicast and broadcast traffic.

Table 4 summarizes the above examples:

table 4 summary of examples

Other options for the common search space contemplated in the present application include, but are not limited to: {1A/0, 1C '} or {1A/0, 1C' }, wherein CIF is introduced only to DCI format 1C, not DCI format 1A/0.

Fig. 8A is a flowchart illustrating operations of a method 800 that may be performed according to an example embodiment. Method 800 may be performed by a user equipment, such as enhanced UE 704 shown in communication system 700.

The method 800 of FIG. 8A begins at operation 802: a plurality of component carriers configured for a wireless communication device are received, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces have one or more common search spaces and a plurality of user-specific search spaces. The method continues at operation 804: receiving a cross-carrier indicator, wherein the cross-carrier indicator is configured to enable cross-carrier signaling for the first component carrier, and continuing at operation 806: determining whether the cross-carrier indicator exists in a control information format carried on a second component carrier according to an association of the control information format with a search space on the second component carrier.

In one embodiment, the UE may be configured with and signaled to cross-carrier operation through upper layers of a communication protocol (e.g., a radio resource control layer), and when there is no cross-carrier signaling, the carrier indication may be defined as 0 bits, and when cross-carrier signaling is implemented, the carrier indication may be defined as 3 bits, wherein the use of a fixed number of bits (e.g., 3 bits) may reduce complexity by eliminating the need to signal and detect the number of CI bits used. Such signaling may be specific to an Uplink (UL) carrier allocation and/or a Downlink (DL) carrier allocation. This signaling may be specific to the user equipment. In addition, such signaling may be specific to individual component carriers. It is important to have a common interpretation between the upper layer scheduler and the UE with respect to the meaning of the carrier indicator. Table 5 below shows an example of how the CI bits are mapped to a specified component carrier in the set of five (5) component carriers of the user equipment when the scheduling of data transmissions on the five (5) component carriers of the user equipment is carried by the first component carrier. It should be understood that the bit mapping shown in table 5 is exemplary, and that other bit mappings are possible.

TABLE 5 exemplary CIF bitmaps

CIF	Carrier allocation
		000	Single carrier wave (carrier wave 1)
001	Carrier 2
		010	Carrier 3
011	Carrier 4
		100	Carrier wave 5

The UE carrier configuration may include a unique identifier for each carrier, which may be used for carrier identification. Furthermore, to enable flexibility in addressing more carriers than direct addressing of 3-bit indicators, the carrier index may be specific to the carrier of the PDCCH on which these allocations are made. For example, if there are 10 carriers, the UE may address the first five carriers according to one PDCCH in the first carrier and the other five carriers according to another PDCCH in the second carrier. Furthermore, by limiting cross-carrier signaling to a particular subset of carriers, the total number of blind decodes can be limited.

As described above, with reference to the details of incorporating CIF in various DCI formats, CI is generally applicable to all DCI formats capable of carrying UE-specific UL or DL allocations. DCI formats 0, 1A, 1B, 1D, 2, and 2A are for UE-specific allocation with C-RNTI scrambling, and may include CIFs for cross-carrier operation. DCI formats 1C, 3, and 3A are not used for UE-specific purposes and are located in a common search space. To provide backward compatibility with LTE release 8 UEs using the same common search space, DCI formats 1C, 3, and 3A may not include CIF. However, in LTE release 8, DCI formats 0 and 1A are used in both the common search space and the UE-specific search space. To ensure backward compatibility with LTE release 8, DCI formats 0 and 1A with carrier indicators may be distinguished from DCI formats 0 and 1A without carrier indicators by a specific RNTI for CRC scrambling for DCI formats in the common search space. For example, DCI formats 0 and 1A with carrier indicators may scramble CRC exclusively with C-RNTI, while DCI formats 0 and 1A without carrier indicators may scramble CRC, for example, with SI-RNTI, P-RNTI, or RA-RNTI.

In various embodiments, the LTE-AUE (e.g., UE 704) may attempt to decode DCI formats 0 and 1A with and without CIF in the common search space. DCI formats 0 and 1A with C-RNTI based CRC scrambling are assumed to include CIF, and DCI formats 0 and 1A with SI/P/RA-RNTI based CRC scrambling are assumed to not include CIF. By doing so, the number of blind decodes is increased by only 6(2 DCI sizes x3 RNTIs). However, the false alarm probability is not increased compared to LTE release 8. This is because the false alarm probability depends not only on the number of blind decodings, but also on the number of RNTIs used for the descrambling operation. In this scheme, the total number of decoding operations is still maintained. Table 6 summarizes the relationship between the DCI format, CRC scrambling, search space, and carrier indication described above.

Table 6-DCI format with carrier indicator

Fig. 8B is a flowchart illustrating the operation of a method 850 in a communication system, performed in accordance with an exemplary embodiment. Method 850 may be performed by a base station, such as serving node (eNB)702 shown in communication system 700.

The method 850 begins with operation 852: control information in a control channel of a communication carrier is formatted with a cross-carrier control indicator. The method ends at operation 854: the control information is scrambled with a scrambling code, wherein the scrambling code is selected according to a format of the control information and a position of the control information within a plurality of search spaces in a control channel.

Fig. 8C is a flowchart illustrating operation of a method 870 in a UE that may be performed in accordance with an example embodiment. The method 870 may be performed by a user equipment, such as the improved UE 704 shown in the communication system 700.

The method 870 begins with operation 872: a plurality of search spaces in a control channel of a communication carrier are searched for scrambled control information. The method continues at operation 874: blind decoding the plurality of search spaces with a plurality of descrambling codes to extract control information. The method ends at operation 876: the presence of the cross-carrier control indicator is determined according to a format of the control information and a location of the control information in the plurality of search spaces.

For ease of explanation, the operations in fig. 8A, 8B, and 8C are shown and described as a series of acts. It is to be understood and appreciated, however, that the methodologies are not limited by the order of acts, as some acts may, in accordance with one or more embodiments, occur in different orders and/or concurrently with other acts from that shown and described herein. For example, those skilled in the art will understand and appreciate that a methodology could alternatively be represented as a series of interrelated states or events, such as in a state diagram. Moreover, not all illustrated acts may be required to implement a methodology in accordance with one or more embodiments.

As indicated above (e.g., see table 1), DCI formats 3 and 3A are size-matched to DCI formats 1A and 0, which means that modified DCI formats 3 'and 3A' with carrier information may be defined to be size-matched to DCI formats 1A 'and 0'. These modifications can be made in the same manner; size matching is achieved by zero padding or by defining a specific use for existing but unused reserved bits. The latter approach is possible because DCI format 3/3a is in a common search space, and the CIF size in the common search space is preferably based on the cell-specific multicarrier configuration.

Alternatively, CIF may be introduced in both DCI formats by Transmit Power Control (TPC) bits in DCI format 3/3a, so that TPC commands can handle not only the carrier in question, but also other carriers. Such cross-carrier power control is useful in high interference conditions when a selected component carrier can transmit more reliable power control commands to a group of user equipment.

If Carrier Information (CI) is included in the 1A/1C DCI format for broadcasting and a change in CIF size is allowed, it would be beneficial to signal the carrier information as early as possible. The signaling may be explicit or implicit. One example of explicit signaling is to use reserved bits in the PBCH to signal the presence and/or size of the CI. After PBCH decoding, the UE knows the CI field and can determine the PDCCH payload size to search for SIB/paging decoding. For implicit signaling, the UE may perform blind decoding on the PDCCH format used to signal resource allocations for system information, paging, and/or random access responses. The presence and/or size of the CI may be determined based on the results of the blind decoding.

Alternatively, cross-carrier broadcast may be achieved by a new SI-RNTI (or P/RA-RNTI) scrambled for PDCCH CRC (as opposed to an explicit CI in the PDCCH). The new SI-RNTI may be obtained from the reserved RNTIs (0000 and FFF4-FFFD, currently reserved for future use in LTE release 8) or other RNTIs.

Another alternative is to use one PDCCH to signal the same broadcast content for two or more component carriers at the cost of scheduling restrictions.

FIG. 9 illustrates an exemplary system 600 capable of supporting the various operations described above. As discussed in connection with fig. 6, system 600 includes eNB 620, which eNB 620 can transmit and/or receive information, signals, data, instructions, commands, bits, symbols, and the like. Fig. 9 also shows a user equipment 610, which user equipment 610 uses "component carrier 1" 630 through "component carrier N" 640 to communicate with eNB 620. User device 610 can send and/or receive information, signals, data, instructions, commands, bits, symbols, and the like. Further, although not shown, it is contemplated that system 600 can include additional base stations and/or user equipment.

In some embodiments, eNB 620 can include a scheduler 922, which scheduler 922 allocates resources on a link (e.g., downlink or uplink) to user equipment 610 and/or any other user equipment (not shown) served by eNB 620. The scheduler 922 may select Resource Blocks (RBs) over one or more subframes intended to carry data associated with the user equipment 610. For example, the scheduler 922 may allocate RBs of a downlink subframe to data transmitted to the user equipment 610, and the scheduler 922 may allocate RBs of an uplink subframe to data transmitted by the user equipment 610. The allocated RBs may be indicated to the user equipment 610 through control channel signaling (e.g., a control information message) included on a control channel such as PDCCH. eNB 620 may also include a search space configuration component 924, the search space configuration component 924 enabling configuration of a search space associated with one or more control information messages. Search space configuration component 924 may operate in conjunction with one or more of "component carrier 1" 630 through "component carrier N" 640. For example, search space configuration component 924 may configure two or more search spaces to be shared between control information messages associated with two or more component carrier transmissions.

In some embodiments, the user equipment 610 shown in fig. 9 may include a carrier grouping component 912, which carrier grouping component 912 may be configured to group one or more component carriers. For example, carrier grouping component 912 can be configured to group component carriers according to DCI sizes of control information carried on the component carriers. The carrier grouping component 912 can also be configured to group component carriers according to a transmission mode utilized by the communication system. The user equipment 610 can also include a control channel monitoring component 914 that enables the user equipment 610 to monitor control channels for "component carrier 1" 630 through "component carrier N" 640. Further, the selection component 916 in the user equipment 610 can be configured to enable selection of a component carrier group, as well as selection of a particular component carrier in the component carrier group. The user equipment 610 can further include a detection component 918 that enables detection of control information messages carried on control channels of "component carrier 1" 630 through "component carrier N" 640. For example, detection component 918 can be configured to blind decode a DCI message in a search space.

FIG. 10 illustrates an apparatus 1000 in which various disclosed embodiments may be implemented. Specifically, the apparatus 1000 shown in fig. 10 may include: at least a portion of a base station, or at least a portion of a user equipment (e.g., eNB 620 and user equipment 610 shown in fig. 6 and 10); and/or at least a portion of a transmitter system or a receiver system (e.g., transmitter system 210 and receiver system 250 shown in fig. 2). The apparatus 1000 shown in fig. 10 may be located in a wireless network and may receive input data through, for example, one or more receivers and/or appropriate receiving and decoding circuitry (e.g., antennas, transceivers, demodulators, etc.). The apparatus 1000 shown in fig. 10 may also transmit output data, for example, via one or more transmitters and/or appropriate coding and transmit circuitry (e.g., antennas, transceivers, modulators, etc.). Additionally or alternatively, the apparatus 1000 shown in fig. 10 may be located in a wired network.

Fig. 10 also illustrates an apparatus 1000 that may include a memory 1002, where the memory 1002 may hold instructions for performing one or more operations such as signal conditioning, analysis, and the like. Additionally, the apparatus 1000 of fig. 10 may include a processor 1004, which processor 1004 may execute instructions stored in a memory 1002 and/or instructions received from another device. For example, the instructions may be related to configuring or operating device 1000 or an associated communication device. It should be noted that while the memory 1002 shown in fig. 10 is depicted as a single block, the memory 1002 may comprise two or more separate memories configured as separate physical and/or logical units. Further, although communicatively connected to the processor 1004, the memory may also be located wholly or partially outside of the apparatus 1000 shown in fig. 10. It is to be further appreciated that one or more components (e.g., scheduler 1022, search space configuration component 1024, carrier grouping component 1012, control channel monitoring component 1014, selection component 1016, and/or detection component 1018 shown in fig. 10) can reside in a memory such as memory 1002.

It is to be understood that the memory described herein in connection with the disclosed embodiments can be either volatile memory or nonvolatile memory, or can contain both volatile and nonvolatile memory. By way of example, and not limitation, nonvolatile memory may include: read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), electrically erasable ROM (EEPROM), or flash memory. The volatile memory may include: random Access Memory (RAM), which acts as external cache memory. By way of example and not limitation, RAM may take many forms, such as Synchronous RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), double-speed SDRAM (DDR SDRAM), Enhanced SDRAM (ESDRAM), Synchlink DRAM (SLDRAM), and direct read Rambus RAM (DRRAM).

Further, it should also be noted that the apparatus 1000 of fig. 10 may be used with a user device or a mobile device, and that the apparatus 1000 may be a module such as an SD card, a network card, a wireless network card, a computer (including laptop, desktop, personal digital assistant PDA), a mobile phone, a smart phone, or any other suitable terminal that may be used to access a network, to name a few. The user equipment accesses the network via an access component (not shown). In one example, the connection between the user equipment and the access component, which may be a base station, and the user equipment a wireless terminal, may be wireless in nature. For example, the terminal and base station may communicate via any suitable wireless protocol, including but not limited to: time Division Multiple Access (TDMA), Code Division Multiple Access (CDMA), Frequency Division Multiple Access (FDMA), Orthogonal Frequency Division Multiplexing (OFDM), FLASHOFDM, Orthogonal Frequency Division Multiple Access (OFDMA), or any other suitable protocol.

The access component may be an access node associated with a wired network or a wireless network. Thus, the access component may be, for example, a router, a switch, etc. The access component may include one or more interfaces, such as a communication module, to communicate with other network nodes. Further, the access component may be a base station (or wireless access point) in a cellular-type network, wherein the base station (or wireless access point) is configured to provide wireless coverage to a plurality of users. These base stations (or wireless access points) may be arranged to provide a contiguous coverage area for one or more cellular telephones and/or other wireless terminals.

It should be understood that the embodiments and features described herein may be implemented by hardware, software, firmware, or any combination thereof. Various embodiments described herein are described in the general context of methods or processes, which may be implemented in one embodiment by a computer program product embedded in a computer-readable medium, where the computer program product includes computer-executable instructions, such as program code, executed by computers in network environments. As described above, the memory and/or computer-readable medium may include removable storage devices and non-removable storage devices, including but not limited to: read Only Memory (ROM), Random Access Memory (RAM), Compact Discs (CD), Digital Versatile Discs (DVD), and the like. Thus, the disclosed embodiments may be implemented on non-transitory computer readable media. When implemented in software, the functions may be stored on or transmitted over as one or more instructions or code on a computer-readable medium. Computer-readable media includes both computer storage media and communication media including any medium that facilitates transfer of a computer program from one place to another. A storage media may be any available media that can be accessed by a general purpose or special purpose computer. By way of example, and not limitation, such computer-readable media can comprise RAM, ROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium that can be used to carry or store desired program code means in the form of instructions or data structures and that can be accessed by a general-purpose or special-purpose computer, or a general-purpose or special-purpose processor.

Also, any connection is properly termed a computer-readable medium. For example, if the software is transmitted from a website, server, or other remote source using a coaxial cable, fiber optic cable, twisted pair, or Digital Subscriber Line (DSL), then the coaxial cable, fiber optic cable, twisted pair, or DSL are included in the definition of medium. Disk and disc, as used herein, includes Compact Disc (CD), laser disc, optical disc, Digital Versatile Disc (DVD), floppy disk and blu-ray disc where disks usually reproduce data magnetically, while discs reproduce data optically with lasers. Combinations of the above should also be included within the scope of computer-readable media.

Generally, program modules may include routines, programs, objects, components, data structures, etc. that perform particular tasks or implement particular abstract data types. Computer-executable instructions, associated data structures, and program modules represent examples of program code for executing steps of the methods disclosed herein. The particular sequence of such executable instructions or associated data structures represents examples of corresponding acts for implementing the functions described in such steps or processes.

The various illustrative logics, logical blocks, modules, and circuits described in connection with the aspects disclosed herein may be implemented or performed with a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination thereof designed to perform the functions described herein. A general-purpose processor may be a microprocessor, but in the alternative, the processor may be any conventional processor, controller, microcontroller, or state machine. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. Additionally, at least one processor may comprise one or more modules operable to perform one or more of the steps and/or actions described above.

For a software implementation, the techniques described herein may be implemented with modules (e.g., procedures, functions, and so on) that perform the functions described herein. The software codes may be stored in memory units and executed by processors. The memory unit may be implemented within the processor and/or external to the processor, in which case it can be communicatively coupled to the processor via various means as is known in the art. Further, at least one processor may include one or more modules operable to perform the functions described herein.

The techniques described herein may be used for various wireless communication systems such as CDMA, TDMA, FDMA, OFDMA, SD-FDMA and other systems. The terms "system" and "network" are often used interchangeably. A CDMA system may implement a radio technology such as Universal Terrestrial Radio Access (UTRA), CDMA2000, etc. UTRA includes wideband CDMA (W-CDMA) and other CDMA variations. Further, cdma2000 covers IS-2000, IS-95 and IS-856 standards. TDMA systems may implement wireless technologies such as global system for mobile communications (GSM). OFDMA systems may implement methods such as evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11(Wi-Fi), IEEE 802.16(WiMAX), IEEE 802.20, and,And so on. UTRA and E-UTRA are part of the Universal Mobile Telecommunications System (UMTS). The 3GPP Long Term Evolution (LTE) is a release of UMTS that employs E-UTRA, which uses OFDMA on the downlink and SC-FDMA on the uplink. UTRA, E-UTRA, UMTS, LTE, and GSM are described in documents from an organization named "third Generation partnership project" (3 GPP). In addition, cdma2000 and UMB are described in documents from an organization named "third generation partnership project 2" (3GPP 2). These wireless communication systems may additionally include peer-to-peer (e.g., user device to user device) ad hoc (ad hoc) network systems that typically use unpaired unlicensed spectrum, 802.xx wireless LANs, bluetooth, and any other short-range or long-rangeWireless communication technology. The disclosed embodiments may also be used in connection with systems that use multiple component carriers. For example, the disclosed embodiments may be used in conjunction with LTE-a systems.

Single carrier frequency division multiple access (SC-FDMA) using single carrier modulation and frequency domain equalization is a technique that can be used with the disclosed embodiments. SC-FDMA has similar performance and substantially similar overall complexity as OFDMA systems. SC-FDMA signal has a low peak-to-average power ratio (PAPR) due to its inherent single carrier structure. SC-FDMA may be used for uplink communications where lower PAPR may benefit user equipment in terms of transmit power efficiency.

Furthermore, various aspects or features described herein may be implemented as a method, apparatus, or article of manufacture using standard programming and/or engineering techniques. The term "article of manufacture" as used herein is intended to encompass a computer program accessible from any computer-readable device, carrier, or media. For example, computer-readable media may include, but are not limited to: magnetic storage devices (e.g., hard disk, floppy disk, magnetic strips, etc.), optical disks (e.g., Compact Disk (CD), Digital Versatile Disk (DVD), etc.), smart cards, and flash memory devices (e.g., EPROM, card, stick, key drive, etc.). In addition, various storage media described herein can represent one or more devices and/or other machine-readable media for storing information. The term "machine-readable medium" can include, but is not limited to: a wireless channel; and various other media capable of storing, containing, and/or carrying instruction(s) and/or data. Additionally, a computer program product may include a computer-readable medium having one or more instructions or code operable to cause a computer to perform the functions described herein.

Further, the steps and/or actions of a method or algorithm described in connection with the aspects disclosed herein may be embodied directly in hardware, in a software module executed by a processor, or in a combination of the two. A software module may reside in RAM memory, flash memory, ROM memory, EPROM memory, EEPROM memory, registers, hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art. An exemplary storage medium may be coupled to the processor such the processor can read information from, and write information to, the storage medium. In the alternative, the storage medium may be integral to the processor. In addition, in some embodiments, the processor and the storage medium may reside in an ASIC. Additionally, the ASIC may reside in user equipment (e.g., 610 of FIG. 12). In the alternative, the processor and the storage medium may reside as discrete components in user equipment (e.g., 610 of FIG. 12). Further, in some embodiments, the steps and/or actions of a method or algorithm may reside as one or any combination or set of codes and/or instructions on a machine readable medium and/or computer readable medium, which may be incorporated into a computer program product.

While the foregoing invention discusses illustrative embodiments, it should be noted that various changes and modifications could be made herein without departing from the scope of the described embodiments as defined by the appended claims. Accordingly, the described embodiments are intended to embrace all such alterations, modifications and variations that fall within the scope of the appended claims. Furthermore, although elements of the described embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated. Moreover, all or a portion of any embodiment may be utilized with all or a portion of any other embodiment, unless stated otherwise.

To the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim. Furthermore, the term "or" as used in the specification or claims is intended to mean an inclusive "or" rather than an exclusive "or". That is, unless otherwise indicated, or otherwise clear from the context, the phrase "X employs A or B" is intended to mean any of the normal inclusive permutations. That is, any of the following examples satisfies the phrase "X employs A or B": x is A; b is used as X; or X employs A and B. In addition, the articles "a" and "an" as used in this application and the appended claims should generally be construed to mean "one or more" unless specified otherwise or clear from context to be directed to a singular form.

Claims (78)

1. A method for wireless communication, comprising:

receiving a plurality of component carriers configured for a wireless communication device, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces comprise one or more common search spaces and a plurality of user-specific search spaces;

receiving a cross-carrier configuration, wherein the cross-carrier configuration comprises an indicator of cross-carrier operation for a first component carrier of the plurality of component carriers; and

determining whether control information for the first component carrier is present in control information formats carried on a second component carrier based on the cross-carrier configuration by decoding the plurality of search spaces according to a first set of control information formats associated with the one or more common search spaces and a second set of control information formats associated with the plurality of user-specific search spaces, the first set of control information formats including at least a first Downlink Control Information (DCI) format having no carrier indicator, the second set of control information formats including at least the first DCI format having a carrier indicator.

2. The method of claim 1, further comprising:

receiving a control channel on the second component carrier, wherein the control channel is encoded using the control information format.

3. The method of claim 1, wherein the first component carrier and the second component carrier are the same component carrier.

4. The method of claim 1, wherein the first component carrier and the second component carrier are different component carriers.

5. The method of claim 1, wherein the control information format is configured to control a downlink grant.

6. The method of claim 1, wherein the second set of control information formats includes at least:

LTE rel-8 and rel-9 DCI formats 1, 1A, 1B, 1C, 1D, 2A, and 2B transmitted over a Physical Downlink Control Channel (PDCCH).

7. The method of claim 1, wherein the control information format is configured to control an uplink grant.

8. The method of claim 1, wherein the first set of control information formats includes at least:

LTE release 8 and release 9DCI formats 0 and 1A transmitted over a Physical Downlink Control Channel (PDCCH).

9. The method of claim 1, wherein the carrier indicator is for unicast traffic and not for broadcast traffic.

10. The method of claim 1, wherein the carrier indicator comprises a Carrier Indicator Field (CIF) consisting of three bits.

11. The method of claim 10, wherein the CIF is located at a beginning of the control information.

12. The method of claim 10, wherein the CIF is user-specific and comprises a unique value for each component carrier.

13. The method of claim 10, wherein the CIF is component carrier specific and values of the CIF for two or more component carriers comprise a same value if control information for the two or more component carriers are located on different component carriers.

14. The method of claim 1, wherein the first set of control information formats includes DCI formats of two different sizes without a carrier indicator and the second set of control information formats includes DCI formats of at least two different sizes with a carrier indicator, wherein cross-carrier control is enabled for unicast traffic and not for broadcast traffic by the carrier indicator.

15. The method of claim 1, wherein the first set of control information formats comprises a second DCI format with a carrier indicator.

16. The method of claim 1, wherein the first set of control information formats comprises the first DCI format with a carrier indicator.

17. The method of claim 1, wherein each control information format of the second set of control information formats comprises a DCI format with a carrier indicator.

18. The method of claim 1, wherein the first set of control information formats includes DCI formats of three sizes including DCI formats of two sizes with carrier indicators and DCI formats of a third size without carrier indicators, and the second set of control information formats includes DCI formats of at least two different sizes with carrier indicators, wherein the method is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

19. The method of claim 1, wherein the first set of control information formats includes DCI formats of four sizes including a first two sizes of DCI formats with carrier indicators and a second two sizes of DCI formats without carrier indicators, and the second set of control information formats includes DCI formats of at least two different sizes with carrier indicators, wherein the method is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

20. An apparatus for wireless communication, comprising:

means for receiving a plurality of component carriers configured for a wireless communication device, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces comprise one or more common search spaces and a plurality of user-specific search spaces;

means for receiving a cross-carrier configuration, wherein the cross-carrier configuration comprises an indicator of cross-carrier operation for a first component carrier of the plurality of component carriers; and

means for determining whether control information for the first component carrier is present in control information formats carried on a second component carrier based on the cross-carrier configuration by decoding the plurality of search spaces according to a first set of control information formats associated with the one or more common search spaces and a second set of control information formats associated with the plurality of user-specific search spaces, the first set of control information formats including at least a first Downlink Control Information (DCI) format having no carrier indicator, the second set of control information formats including at least the first DCI format having a carrier indicator.

21. An apparatus for wireless communication, comprising:

a processor; and

a memory comprising processor-executable code, wherein the processor-executable code, when executed by the processor, configures the apparatus to perform operations comprising:

receiving a plurality of component carriers configured for a wireless communication device, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces comprise one or more common search spaces and a plurality of user-specific search spaces;

receiving a cross-carrier configuration, wherein the cross-carrier configuration comprises an indicator of cross-carrier operation for a first component carrier of the plurality of component carriers; and

determining whether control information for the first component carrier is present in control information formats carried on a second component carrier based on the cross-carrier configuration by decoding the plurality of search spaces according to a first set of control information formats associated with the one or more common search spaces and a second set of control information formats associated with the plurality of user-specific search spaces, the first set of control information formats including at least a first Downlink Control Information (DCI) format having no carrier indicator, the second set of control information formats including at least the first DCI format having a carrier indicator.

22. The apparatus of claim 21, further configured to:

receiving a control channel on the second component carrier, wherein the control channel is encoded using the control information format.

23. The apparatus of claim 21, wherein the first component carrier and the second component carrier are the same component carrier.

24. The apparatus of claim 21, wherein the first component carrier and the second component carrier are different component carriers.

25. The apparatus of claim 21, wherein the control information format is configured to control a downlink grant.

26. The apparatus of claim 21, wherein the second set of control information formats comprises at least:

LTE rel-8 and rel-9 DCI formats 1, 1A, 1B, 1C, 1D, 2A, and 2B transmitted over a Physical Downlink Control Channel (PDCCH).

27. The apparatus of claim 21, wherein the control information format is configured to control an uplink grant.

28. The apparatus of claim 21, wherein the first set of control information formats comprises at least:

LTE release 8 and release 9DCI formats 0 and 1A transmitted over a Physical Downlink Control Channel (PDCCH).

29. The apparatus of claim 21, wherein the carrier indicator is for unicast traffic and not for broadcast traffic.

30. The apparatus of claim 21, wherein the carrier indicator comprises a Carrier Indicator Field (CIF) consisting of three bits.

31. The apparatus of claim 30, wherein the CIF is located at a start of the control information.

32. The apparatus of claim 30, wherein the CIF is user-specific and comprises a unique value for each component carrier.

33. The apparatus of claim 30, wherein the CIF is component carrier specific and values of the CIF for two or more component carriers comprise a same value if control information for the two or more component carriers are located on different component carriers.

34. The apparatus of claim 21, wherein the first set of control information formats includes DCI formats of two different sizes without a carrier indicator and the second set of control information formats includes DCI formats of at least two different sizes with a carrier indicator, wherein cross-carrier control is enabled for unicast traffic and not for broadcast traffic by the carrier indicator.

35. The apparatus of claim 21, wherein the first set of control information formats comprises a second DCI format with a carrier indicator.

36. The apparatus of claim 21, wherein the first set of control information formats comprises the first DCI format with a carrier indicator.

37. The apparatus of claim 21, wherein each control information format of the second set of control information formats comprises a DCI format with a carrier indicator.

38. The apparatus of claim 21, wherein the first set of control information formats comprises DCI formats of three sizes including DCI formats of two sizes with carrier indicators and a DCI format of a third size without carrier indicators, and the second set of control information formats comprises DCI formats of at least two different sizes with carrier indicators, wherein the apparatus is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

39. The apparatus of claim 21, wherein the first set of control information formats comprises four sizes of DCI formats including a first two sizes of DCI formats with carrier indicators and a second two sizes of DCI formats without carrier indicators, and the second set of control information formats comprises at least two different sizes of DCI formats with carrier indicators, wherein the apparatus is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

40. A method for wireless communication, comprising:

transmitting a plurality of component carriers configured for a wireless communication device, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces comprise one or more common search spaces and a plurality of user-specific search spaces; and

transmitting a cross-carrier configuration, wherein the cross-carrier configuration comprises an indicator of cross-carrier operation for a first component carrier of the plurality of component carriers; and

transmitting control information for the first component carrier in control information formats carried on a second component carrier, the control information encoded according to a first set of control information formats associated with the one or more common search spaces and a second set of control information formats associated with the plurality of user-specific search spaces, the first set of control information formats including at least a first Downlink Control Information (DCI) format without a carrier indicator, the second set of control information formats including at least the first DCI format with a carrier indicator.

41. The method of claim 40, further comprising:

transmitting a control channel on the second component carrier, wherein the control channel is encoded using the control information format.

42. The method of claim 40, wherein the first component carrier and the second component carrier are the same component carrier.

43. The method of claim 40, wherein the first component carrier and the second component carrier are different component carriers.

44. The method of claim 40, wherein the control information format is configured to control a downlink grant.

45. The method of claim 40, wherein the second set of control information formats comprises at least:

LTE rel-8 and rel-9 DCI formats 1, 1A, 1B, 1C, 1D, 2A, and 2B transmitted over a Physical Downlink Control Channel (PDCCH).

46. The method of claim 40, wherein the control information format is configured to control an uplink grant.

47. The method of claim 40, wherein the first set of control information formats comprises at least:

LTE release 8 and release 9DCI formats 0 and 1A transmitted over a Physical Downlink Control Channel (PDCCH).

48. The method of claim 40, wherein the carrier indicator is for unicast traffic and not for broadcast traffic.

49. The method of claim 40, wherein the carrier indicator comprises a Carrier Indicator Field (CIF) consisting of three bits.

50. The method of claim 49, wherein the CIF is located at a start of the control information.

51. The method of claim 49, wherein the CIF is user-specific and includes a unique value for each component carrier.

52. The method of claim 49, wherein the CIF is component carrier specific and the values of the CIF for two or more component carriers comprise a same value if control information for the two or more component carriers are located on different component carriers.

53. The method of claim 40, wherein the first set of control information formats comprises two different sizes of DCI formats without a carrier indicator and the second set of control information formats comprises at least two different sizes of DCI formats with a carrier indicator, wherein cross-carrier control is enabled for unicast traffic and not for broadcast traffic by the carrier indicator.

54. The method of claim 40, wherein the first set of control information formats comprises a second DCI format with a carrier indicator.

55. The method of claim 40, wherein the first set of control information formats comprises the first DCI format with a carrier indicator.

56. The method of claim 40, wherein each control information format of the second set of control information formats comprises a DCI format with a carrier indicator.

57. The method of claim 40, wherein the first set of control information formats comprises three sizes of DCI formats including two sizes of DCI formats with carrier indicators and a third size of DCI formats without carrier indicators, and the second set of control information formats comprises at least two different sizes of DCI formats with carrier indicators, wherein the method is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

58. The method of claim 40, wherein the first set of control information formats comprises four sizes of DCI formats including a first two sizes of DCI formats with carrier indicators and a second two sizes of DCI formats without carrier indicators, and the second set of control information formats comprises at least two different sizes of DCI formats with carrier indicators, wherein the method is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

59. An apparatus for wireless communication, comprising:

means for transmitting a plurality of component carriers configured for a wireless communication device, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces comprise one or more common search spaces and a plurality of user-specific search spaces; and

means for transmitting a cross-carrier configuration, wherein the cross-carrier configuration comprises an indicator of cross-carrier operation for a first component carrier of the plurality of component carriers; and

means for transmitting control information for the first component carrier in control information formats carried on a second component carrier, the control information encoded according to a first set of control information formats associated with the one or more common search spaces and a second set of control information formats associated with the plurality of user-specific search spaces, the first set of control information formats including at least a first Downlink Control Information (DCI) format having no carrier indicator, the second set of control information formats including at least the first DCI format having a carrier indicator.

60. An apparatus for wireless communication, comprising:

a processor; and

a memory comprising processor-executable code, wherein the processor-executable code, when executed by the processor, configures the apparatus to perform operations comprising:

transmitting a plurality of component carriers configured for a wireless communication device, the plurality of component carriers comprising a plurality of search spaces, wherein the plurality of search spaces comprise one or more common search spaces and a plurality of user-specific search spaces; and

transmitting a cross-carrier configuration, wherein the cross-carrier configuration comprises an indicator of cross-carrier operation for a first component carrier of the plurality of component carriers; and

transmitting control information for the first component carrier in control information formats carried on a second component carrier, the control information encoded according to a first set of control information formats associated with the one or more common search spaces and a second set of control information formats associated with the plurality of user-specific search spaces, the first set of control information formats including at least a first Downlink Control Information (DCI) format without a carrier indicator, the second set of control information formats including at least the first DCI format with a carrier indicator.

61. The apparatus of claim 60, further configured to:

receiving a control channel on the second component carrier, wherein the control channel is encoded using the control information format.

62. The apparatus of claim 60, wherein the first component carrier and the second component carrier are the same component carrier.

63. The apparatus of claim 60, wherein the first component carrier and the second component carrier are different component carriers.

64. The apparatus of claim 60, wherein the control information format is configured to control a downlink grant.

65. The apparatus of claim 60, wherein the second set of control information formats comprises at least:

LTE rel-8 and rel-9 DCI formats 1, 1A, 1B, 1C, 1D, 2A, and 2B transmitted over a Physical Downlink Control Channel (PDCCH).

66. The apparatus of claim 60, wherein the control information format is configured to control an uplink grant.

67. The apparatus of claim 60, wherein the first set of control information formats comprises at least:

LTE release 8 and release 9DCI formats 0 and 1A transmitted over a Physical Downlink Control Channel (PDCCH).

68. The apparatus of claim 60, wherein the carrier indicator is for unicast traffic and not for broadcast traffic.

69. The apparatus of claim 60, wherein the carrier indicator comprises a Carrier Indicator Field (CIF) consisting of three bits.

70. The apparatus of claim 69, wherein the CIF is located at a start of the control information.

71. The apparatus of claim 69, wherein the CIF is user-specific and comprises a unique value for each component carrier.

72. The apparatus of claim 69, wherein the CIF is component carrier specific and values of the CIF for two or more component carriers comprise a same value if control information for the two or more component carriers are located on different component carriers.

73. The apparatus of claim 60, wherein the first set of control information formats comprises two different sizes of DCI formats without a carrier indicator and the second set of control information formats comprises at least two different sizes of DCI formats with a carrier indicator, wherein cross-carrier control is enabled for unicast traffic and not for broadcast traffic by the carrier indicator.

74. The apparatus of claim 60, wherein the first set of control information formats comprises a second DCI format with a carrier indicator.

75. The apparatus of claim 60, wherein the first set of control information formats comprises the first DCI format with a carrier indicator.

76. The apparatus of claim 60, wherein each control information format of the second set of control information formats comprises a DCI format with a carrier indicator.

77. The apparatus of claim 60, wherein the first set of control information formats comprises three sizes of DCI formats including two sizes of DCI formats with carrier indicators and a third size of DCI formats without carrier indicators, and the second set of control information formats comprises at least two different sizes of DCI formats with carrier indicators, wherein the apparatus is backward compatible with LTE release 8 broadcast traffic and unicast traffic.

78. The apparatus of claim 60, wherein the first set of control information formats comprises four sizes of DCI formats including a first two sizes of DCI formats with carrier indicators and a second two sizes of DCI formats without carrier indicators, and the second set of control information formats comprises at least two different sizes of DCI formats with carrier indicators, wherein the apparatus is backward compatible with LTE release 8 broadcast traffic and unicast traffic.