WO2011071557A1

WO2011071557A1 - Method and apparatus to determine intra-node-b cells in td-scdma systems

Info

Publication number: WO2011071557A1
Application number: PCT/US2010/032382
Authority: WO
Inventors: Tom Chin; Guangming Shi; Kuo-Chun Lee
Original assignee: Qualcomm Inc
Current assignee: Qualcomm Inc
Priority date: 2009-12-09
Filing date: 2010-04-26
Publication date: 2011-06-16
Anticipated expiration: 2012-06-09
Also published as: TW201136200A

Abstract

The first and second codes are linked by a given relationship. Application to cell search in TD SCDMA systems. A method for wireless communications includes obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and determining, based on the first code, at least a second code used in a second cell, wherein the second code comprises a scrambling code or a basic midamble code. The method may further include searching for a cell using the second code.

Description

METHOD AND APPARATUS TO DETERMINE INTRA-NODE-B CELLS

IN TD-SCDMA SYSTEMS

CROSS-REFERENCE TO RELATED APPLICATION(S)

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 61/285,076, entitled "METHOD AND APPARATUS TO DETERMINE INTRA- NODE-B CELLS IN TD-SCDMA SYSTEMS," filed on December 9, 2009, which is expressly incorporated by reference herein in its entirety.

BACKGROUND

Field

[0002] Certain aspects of the present disclosure generally relate to wireless communication systems and, more particularly, to methods and apparatus for determining intra-Node-B cells in Time Division Synchronous Code Division Multiple Access (TD-SCDMA) systems.

Background

[0003] Wireless communication networks are widely deployed to provide various communication services such as telephony, video, data, messaging, broadcasts, and so on. Such networks, which are usually multiple access networks, support communications for multiple users by sharing the available network resources. One example of such a network is the Universal Terrestrial Radio Access Network (UTRAN). The UTRAN is the radio access network (RAN) defined as a part of the Universal Mobile Telecommunications System (UMTS), a third generation (3G) mobile phone technology supported by the 3rd Generation Partnership Project (3 GPP). The UMTS, which is the successor to Global System for Mobile Communications (GSM) technologies, currently supports various air interface standards, such as Wideband-Code Division Multiple Access (W-CDMA), Time Division-Code Division Multiple Access (TD-CDMA), and Time Division-Synchronous Code Division Multiple Access (TD- SCDMA). For example, China is pursuing TD-SCDMA as the underlying air interface in the UTRAN architecture with its existing GSM infrastructure as the core network. The UMTS also supports enhanced 3G data communications protocols, such as High Speed Downlink Packet Data (HSDPA), which provides higher data transfer speeds and capacity to associated UMTS networks.

[0004] As the demand for mobile broadband access continues to increase, research and development continue to advance the UMTS technologies not only to meet the growing demand for mobile broadband access, but also to advance and enhance the user experience with mobile communications.

SUMMARY

[0005] Aspects of the disclosure generally relate to allocating downlink synchronization (SYNC DL), scrambling, and midamble codes to provide for recognition of multiple cells belonging to the same Node B.

[0006] In an aspect of the disclosure, a method for wireless communications is provided. The method generally includes obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and determining, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code.

[0007] In an aspect of the disclosure, an apparatus for wireless communications is provided. The apparatus generally includes at least one processor and a memory coupled to the at least one processor. The at least one processor is typically configured to obtain a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and to determine, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code.

[0008] In an aspect of the disclosure, an apparatus for wireless communication is provided. The apparatus generally includes means for obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and means for determining, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code. [0009] In an aspect of the disclosure, a computer-program product for wireless communications is provided. The computer-program product generally includes a computer-readable medium having code for obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and determining, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code.

[0010] In an aspect of the disclosure, a method for wireless communications by a Node B is provided. The method generally includes communicating in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code; and communicating in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a defined relationship.

[0011] In an aspect of the disclosure, an apparatus for wireless communications by a Node B is provided. The apparatus generally includes at least one processor and a memory coupled to the at least one processor. The at least one processor is typically configured to communicate in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code; and to communicate in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a defined relationship.

[0012] In an aspect of the disclosure, an apparatus for wireless communications by a Node B is provided. The apparatus generally includes means for communicating in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code; and means for communicating in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a defined relationship.

[0013] In an aspect of the disclosure, a computer-program product for wireless communications by a Node B is provided. The computer-program product generally includes a computer-readable medium having code for communicating in a first cell using a first code, wherein the first code comprises a scrambling code or a midamble code; and communicating in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a defined relationship.

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] So that the manner in which the above -recited features of the present disclosure can be understood in detail, a more particular description, briefly summarized above, may be had by reference to aspects, some of which are illustrated in the appended drawings in which like reference characters identify correspondingly throughout. It is to be noted, however, that the appended drawings illustrate only certain typical aspects of this disclosure and are therefore not to be considered limiting of its scope, for the description may admit to other equally effective aspects.

[0015] FIG. 1 is a block diagram conceptually illustrating an example of a telecommunications system in accordance with certain aspects of the present disclosure.

[0016] FIG. 2 is a block diagram conceptually illustrating an example of a frame structure in a telecommunications system in accordance with certain aspects of the present disclosure.

[0017] FIG. 3 is a block diagram conceptually illustrating an example of a Node B in communication with a user equipment device (UE) in a telecommunications system in accordance with certain aspects of the present disclosure.

[0018] FIG. 4 illustrates an example Time Division Synchronous Code Division Multiple Access (TD-SCDMA) frame in accordance with certain aspects of the present disclosure.

[0019] FIG. 5 is a table illustrating correspondence between downlink synchronization (SYNC DL) codes, scrambling codes, and midamble codes for use by cells in accordance with certain aspects of the present disclosure.

[0020] FIG. 6A illustrates an example single-cell Node B configuration in accordance with certain aspects of the present disclosure. [0021] FIG. 6B illustrates an example multiple-cell Node B configuration in accordance with certain aspects of the present disclosure.

[0022] FIG. 7 is a table illustrating an example allocation of SYNC DL and scrambling/midamble code IDs in an effort to provide for recognition of cells associated with the same Node B in accordance with certain aspects of the present disclosure.

[0023] FIG. 8 is a functional block diagram conceptually illustrating example blocks executed to utilize the above allocation to determine codes used by other cells, from the perspective of a user equipment device (UE), in accordance with certain aspects of the present disclosure.

[0024] FIG. 9 is a functional block diagram conceptually illustrating example blocks executed to communicate in cells according to the above code allocation, from the perspective of a Node B, in accordance with certain aspects of the present disclosure.

[0025] FIG. 10 illustrates searching for intra-Node-B cells using the example code allocation of FIG. 7 in accordance with certain aspects of the present disclosure.

DETAILED DESCRIPTION

[0026] The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to represent the only configurations in which the concepts described herein may be practiced. The detailed description includes specific details for the purpose of providing a thorough understanding of the various concepts. However, it will be apparent to those skilled in the art that these concepts may be practiced without these specific details. In some instances, well-known structures and components are shown in block diagram form in order to avoid obscuring such concepts.

AN EXAMPLE TELECOMMUNICATIONS SYSTEM

[0027] Turning now to FIG. 1 , a block diagram is shown illustrating an example of a telecommunications system 100. The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards. By way of example and without limitation, the aspects of the present disclosure illustrated in FIG. 1 are presented with reference to a UMTS system employing a TD-SCDMA standard. In this example, the UMTS system includes a radio access network (RAN) 102 (e.g., UTRAN) that provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The RAN 102 may be divided into a number of Radio Network Subsystems (RNSs) such as an RNS 107, each controlled by a Radio Network Controller (RNC) such as an RNC 106. For clarity, only the RNC 106 and the RNS 107 are shown; however, the RAN 102 may include any number of RNCs and RNSs in addition to the RNC 106 and RNS 107. The RNC 106 is an apparatus responsible for, among other things, assigning, reconfiguring and releasing radio resources within the RNS 107. The RNC 106 may be interconnected to other RNCs (not shown) in the RAN 102 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.

[0028] The geographic region covered by the RNS 107 may be divided into a number of cells, with a radio transceiver apparatus serving each cell. A radio transceiver apparatus is commonly referred to as a Node B in UMTS applications, but may also be referred to by those skilled in the art as a base station (BS), a base transceiver station (BTS), a radio base station, a radio transceiver, a transceiver function, a basic service set (BSS), an extended service set (ESS), an access point (AP), or some other suitable terminology. For clarity, two Node Bs 108 are shown; however, the RNS 107 may include any number of wireless Node Bs. The Node Bs 108 provide wireless access points to a core network 104 for any number of mobile apparatuses. Examples of a mobile apparatus include a cellular phone, a smart phone, a session initiation protocol (SIP) phone, a laptop, a notebook, a netbook, a smartbook, a personal digital assistant (PDA), a satellite radio, a global positioning system (GPS) device, a multimedia device, a video device, a digital audio player (e.g., MP3 player), a camera, a game console, or any other similar functioning device. The mobile apparatus is commonly referred to as user equipment (UE) in UMTS applications, but may also be referred to by those skilled in the art as a mobile station (MS), a subscriber station, a mobile unit, a subscriber unit, a wireless unit, a remote unit, a mobile device, a wireless device, a wireless communications device, a remote device, a mobile subscriber station, an access terminal (AT), a mobile terminal, a wireless terminal, a remote terminal, a handset, a terminal, a user agent, a mobile client, a client, or some other suitable terminology. For illustrative purposes, three UEs 110 are shown in communication with the Node Bs 108. The downlink (DL), also called the forward link, refers to the communication link from a Node B to a UE, and the uplink (UL), also called the reverse link, refers to the communication link from a UE to a Node B.

[0029] The core network 104, as shown, includes a GSM core network. However, as those skilled in the art will recognize, the various concepts presented throughout this disclosure may be implemented in a RAN, or other suitable access network, to provide UEs with access to types of core networks other than GSM networks.

[0030] In this example, the core network 104 supports circuit-switched services with a mobile switching center (MSC) 112 and a gateway MSC (GMSC) 114. One or more RNCs, such as the RNC 106, may be connected to the MSC 112. The MSC 112 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 112 also includes a visitor location register (VLR) (not shown) that contains subscriber- related information for the duration that a UE is in the coverage area of the MSC 112. The GMSC 114 provides a gateway through the MSC 112 for the UE to access a circuit- switched network 116. The GMSC 114 includes a home location register (HLR) (not shown) containing subscriber data, such as the data reflecting the details of the services to which a particular user has subscribed. The HLR is also associated with an authentication center (AuC) that contains subscriber-specific authentication data. When a call is received for a particular UE, the GMSC 114 queries the HLR to determine the UE's location and forwards the call to the particular MSC serving that location.

[0031] The core network 104 also supports packet-data services with a serving GPRS support node (SGSN) 118 and a gateway GPRS support node (GGSN) 120. GPRS, which stands for General Packet Radio Service, is designed to provide packet- data services at speeds higher than those available with standard GSM circuit-switched data services. The GGSN 120 provides a connection for the RAN 102 to a packet-based network 122. The packet-based network 122 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 120 is to provide the UEs 110 with packet-based network connectivity. Data packets are transferred between the GGSN 120 and the UEs 110 through the SGSN 118, which performs primarily the same functions in the packet-based domain as the MSC 112 performs in the circuit-switched domain. [0032] The UMTS air interface is a spread spectrum Direct-Sequence Code Division Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data over a much wider bandwidth through multiplication by a sequence of pseudorandom bits called chips. The TD-SCDMA standard is based on such direct sequence spread spectrum technology and additionally calls for a time division duplexing (TDD), rather than a frequency division duplexing (FDD) as used in many FDD mode UMTS/W-CDMA systems. TDD uses the same carrier frequency for both the uplink (UL) and downlink (DL) between a Node B 108 and a UE 110, but divides uplink and downlink transmissions into different time slots in the carrier.

[0033] FIG. 2 shows a frame structure 200 for a TD-SCDMA carrier. The TD- SCDMA carrier, as illustrated, has a frame 202 that is 10 ms in length. The frame 202 has two 5 ms subframes 204, and each of the subframes 204 includes seven time slots, TS0 through TS6. The first time slot, TS0, is usually allocated for downlink communication, while the second time slot, TS1, is usually allocated for uplink communication. The remaining time slots, TS2 through TS6, may be used for either uplink or downlink, which allows for greater flexibility during times of higher data transmission times in either the uplink or downlink directions. A downlink pilot time slot (DwPTS) 206, a guard period (GP) 208, and an uplink pilot time slot (UpPTS) 210 (also known as the uplink pilot channel (UpPCH)) are located between TS0 and TS1. Each time slot, TS0-TS6, may allow data transmission multiplexed on a maximum of 16 code channels. Data transmission on a code channel includes two data portions 212 separated by a midamble 214 and followed by a guard period (GP) 216. The midamble 214 may be used for features, such as channel estimation, while the GP 216 may be used to avoid inter-burst interference.

[0034] FIG. 3 is a block diagram of a Node B 310 in communication with a UE 350 in a RAN 300, where the RAN 300 may be the RAN 102 in FIG. 1, the Node B 310 may be the Node B 108 in FIG. 1, and the UE 350 may be the UE 110 in FIG. 1. In the downlink communication, a transmit processor 320 may receive data from a data source 312 and control signals from a controller/processor 340. The transmit processor 320 provides various signal processing functions for the data and control signals, as well as reference signals (e.g., pilot signals). For example, the transmit processor 320 may provide cyclic redundancy check (CRC) codes for error detection, coding and interleaving to facilitate forward error correction (FEC), mapping to signal constellations based on various modulation schemes (e.g., binary phase-shift keying (BPSK), quadrature phase-shift keying (QPSK), M-phase-shift keying (M-PSK), M- quadrature amplitude modulation (M-QAM), and the like), spreading with orthogonal variable spreading factors (OVSF), and multiplying with scrambling codes to produce a series of symbols. Channel estimates from a channel processor 344 may be used by a controller/processor 340 to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor 320. These channel estimates may be derived from a reference signal transmitted by the UE 350 or from feedback contained in the midamble 214 (FIG. 2) from the UE 350. The symbols generated by the transmit processor 320 are provided to a transmit frame processor 330 to create a frame structure. The transmit frame processor 330 creates this frame structure by multiplexing the symbols with a midamble 214 (FIG. 2) from the controller/processor 340, resulting in a series of frames. The frames are then provided to a transmitter 332, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through smart antennas 334. The smart antennas 334 may be implemented with beam steering bidirectional adaptive antenna arrays or other similar beam technologies.

[0035] At the UE 350, a receiver 354 receives the downlink transmission through an antenna 352 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 354 is provided to a receive frame processor 360, which parses each frame, and provides the midamble 214 (FIG. 2) to a channel processor 394 and the data, control, and reference signals to a receive processor 370. The receive processor 370 then performs the inverse of the processing performed by the transmit processor 320 in the Node B 310. More specifically, the receive processor 370 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B 310 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 394. The soft decisions are then decoded and deinterleaved to recover the data, control, and reference signals. The CRC codes are then checked to determine whether the frames were successfully decoded. The data carried by the successfully decoded frames will then be provided to a data sink 372, which represents applications running in the UE 350 and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor 390. When frames are unsuccessfully decoded by the receiver processor 370, the controller/processor 390 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[0036] In the uplink, data from a data source 378 and control signals from the controller/processor 390 are provided to a transmit processor 380. The data source 378 may represent applications running in the UE 350 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B 310, the transmit processor 380 provides various signal processing functions including CRC codes, coding and interleaving to facilitate FEC, mapping to signal constellations, spreading with OVSFs, and scrambling to produce a series of symbols. Channel estimates, derived by the channel processor 394 from a reference signal transmitted by the Node B 310 or from feedback contained in the midamble transmitted by the Node B 310, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 380 will be provided to a transmit frame processor 382 to create a frame structure. The transmit frame processor 382 creates this frame structure by multiplexing the symbols with a midamble 214 (FIG. 2) from the controller/processor 390, resulting in a series of frames. The frames are then provided to a transmitter 356, which provides various signal conditioning functions including amplification, filtering, and modulating the frames onto a carrier for uplink transmission over the wireless medium through the antenna 352.

[0037] The uplink transmission is processed at the Node B 310 in a manner similar to that described in connection with the receiver function at the UE 350. A receiver 335 receives the uplink transmission through the antenna 334 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 335 is provided to a receive frame processor 336, which parses each frame, and provides the midamble 214 (FIG. 2) to the channel processor 344 and the data, control, and reference signals to a receive processor 338. The receive processor 338 performs the inverse of the processing performed by the transmit processor 380 in the UE 350. The data and control signals carried by the successfully decoded frames may then be provided to a data sink 339 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 340 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[0038] The controller/processors 340 and 390 may be used to direct the operation at the Node B 310 and the UE 350, respectively. For example, the controller/processors 340 and 390 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer- readable media of memories 342 and 392 may store data and software for the Node B 310 and the UE 350, respectively. A scheduler/processor 346 at the Node B 310 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.

AN EXAMPLE TD-SCDMA FRAME

[0039] FIG. 4 illustrates an example Time Division Synchronous Code Division Multiple Access (TD-SCDMA) frame 400 in accordance with certain aspects of the present disclosure. As described above for the frame structure 200 of FIG. 2, the TD- SCDMA frame 400 may, for example, comprise a 10 ms frame subdivided into two 5 ms sub frames 204.

[0040] Each of the subframes 204 may comprise seven traffic timeslots (TSs) 420 for uplink (UL) and downlink (DL) communications. TD-SCDMA is based on time division and code division to allow multiple UEs to share the same radio bandwidth. The downlink and uplink transmissions share the same bandwidth in different TSs. In each time slot, there are multiple code channels. For example, as illustrated in FIG. 4, there may be one DL time slot (TSO) followed by three UL time slots (TS1 - TS3), which are, in turn, followed by three DL time slots (TS4 - TS6). Typically, TSO is allocated for system overhead channels (e.g., P-CCPCH, S-CCPCH, PICH, etc.), and TS1 - TS6 are allocated for traffic channels (e.g., DPCH, HS-PDSCH, E-PUCH). As illustrated in FIG. 4, the TSO may for downlink and may convey control messages, such as the broadcast channel (BCH), while TS1 may be allocated for uplink. [0041] In each subframe 204, there may exist two switching points (transition from uplink to downlink and vice versa) that separate the uplink and the downlink. A first switching point may be located at a guard period (GP) 208 between a Downlink Pilot Timeslot (DwPTS) 206 and an Uplink Pilot Timeslot (UpPTS) 210. A second switching point may occur anywhere between the end of TSl and the end of TS6. For example, FIG. 4 shows a switch of transmission direction from TS3 (UL) to TS4 (DL).

[0042] The second switching point may determine the traffic nature of a particular subframe, which may be symmetric or asymmetric. In the asymmetric mode, at least one uplink timeslot and one downlink timeslot may be configured for traffic per subframe, and there may be an uneven number of downlink and uplink timeslots per subframe. In the symmetric mode, three uplink timeslots and three downlink timeslots may be configured for traffic per subframe (e.g., the TS4-TS6 for downlink and the TS1-TS3 for uplink). As illustrated in FIG. 4, the position of the DwPTS 206, GP 208, and UpPTS 210 may be between the TSO and TSl whatever the level of asymmetry may be.

[0043] The DwPTS 206 may be utilized for downlink synchronization. The GP 208 located between the DwPTS 206 and UpPTS 210 may determine a maximum cell size. The UpPTS 210 may be used by the Node B to determine a received power level and a received timing from the UE. As illustrated in FIG. 4, each of the timeslots 420 may comprise two data fields 212. A midamble 214 may be located between these two data fields, and it may be utilized as a training sequence for channel estimation, power measurements, and synchronization.

AN EXAMPLE CODE ALLOCATION FOR DETERMINING INTRA-NODE-Bs

[0044] In TD-SCDMA systems, each cell may transmit a specific SYNC DL code (used for pilot signal) on the DwPTS 206. In addition, each cell may have a cell- specific scrambling code (used for signal separation between different cells) and midamble code 214 in the middle of data 212. There are a total of 32 different SYNC DL codes, 128 different scrambling codes, and 128 different midamble codes. The TD-SCDMA standards specify correspondence between these available SYNC DL codes, scrambling codes, and midamble codes. In FIG. 5, Table 500 shows this correspondence. For example, if a cell uses SYNC DL code 1, then the cell may only use scrambling code or midamble code 4, 5, 6, or 7. If the cell uses scrambling code 4, then the cell may only use midamble code 4.

[0045] As shown in FIGs. 6 A and 6B, there are two kinds of Node B configurations: single-cell or multi-cell. In FIG. 6A, the Node B 602 is configured for communication using a single cell 604 (also referred to as a sector). In FIG. 6B, the Node B 602 is configured for communication using three cells 606 (i.e., three sectors).

[0046] However, the above SYNC DL/scrambling/midamble code allocation according to the TD-SCDMA standards does not provide any rules to indicate that the multiple cells belong to the same physical node, Node B. Consequently, user equipment (UE) in a source cell has no way to optimize a search for a neighboring target cell that belongs to the same Node B or a neighboring target cell that belongs to an adjacent Node B. Furthermore, when a target cell is identified, there is no protocol to confirm that the target cell is associated with the same Node B. Therefore, the UE must negotiate (from scratch) timing synchronization with the target cell regardless of whether the target cell belongs to the same Node B.

[0047] Accordingly, what is needed are techniques and apparatus to provide for recognition of cells associated with the same Node B.

[0048] According to certain aspects of the present disclosure, a method to allocate the SYNC DL/scrambling/midamble codes may allow for such recognition of cells belonging to the same Node B. The following rules may be applied:

• Rule #1 : The first 96 scrambling or midamble codes, i.e., 0 - 95 indicate that a Node B is a multiple-cell Node B.

• Rule #2: The last 32 scrambling or midamble codes, i.e., 96 ~ 127 indicate that a Node B is a single-cell Node B.

• Rule #3: If two cells have the scrambling or midamble codes satisfying Rule #1, then the two cells belong to the same Node B if the difference between their codes is either 32 or 64.

[0049] FIG. 7 depicts a table 700 illustrating an example allocation of SYNC DL and scrambling/midamble codes based on these rules. With this allocation, up to 64 different Node Bs may be differentiated, and up to 32 Node Bs may communicate using the three-cell configuration of FIG. 6B.

[0050] FIG. 8 is a functional block diagram conceptually illustrating example blocks 800 executed to utilize the above allocation to determine codes used by other cells, from the perspective of a UE device, for example. Operations illustrated by the blocks 800 may be executed, for example, at the processor(s) 370 and/or 390 of the UE 350 from FIG. 3. The operations may begin, at block 802, by obtaining a first code used in a first cell. The first code may be a scrambling code or a basic midamble code. At block 804, based on the first code, the UE may determine at least a second code used in a second cell. The second code may be a scrambling code or a basic midamble code.

[0051] For some aspects, the UE may also detect a transmission from the second cell with the second code at block 806 and communicate in the second cell using the second code at block 808. For some aspects, the UE may determine, based on the first code, that the Node B communicates in multiple cells. For some aspects, the UE may determine, based on the first code, a SYNC DL code used by the Node B for communicating in the second cell. For some aspects, the UE may transmit to the Node B in the first cell using an uplink timing, perform a handover to the second cell, and then transmit to the Node B in the second cell utilizing the same uplink timing.

[0052] Thus, according to aspects of the present disclosure, the UE may be able to quickly identify cells associated with the same Node B based on searching for a small number of scrambling or midamble codes. Negotiation of timing frames may be reduced or eliminated in some aspects. Handover performance may be improved in certain aspects, as described in greater detail below.

[0053] FIG. 9 is a functional block diagram conceptually illustrating example blocks 900 executed to communicate in cells according to the above code allocation, from the perspective of a Node B, for example. Operations illustrated by the blocks 900 may be executed, for example, at the processor(s) 320 and/or 340 of the Node B 310 from FIG. 3. The operations may begin, at block 902, by communicating in a first cell using a first code. The first code may be a scrambling code or a basic midamble code. At block 904, the Node B may communicate in at least a second cell using at least a second code, wherein values of the first code and the at least the second code have a defined relationship. The at least the second code may be a scrambling code or a basic midamble code.

[0054] For some aspects, the values of the first and the at least the second codes may differ by an integer amount according to the defined relationship. For example, the integer amount may be 2^N, wherein N is a positive integer (e.g., N = 5 as illustrated in FIG. 7). For some aspects, the Node B may further communicate in the at least the second cell and at least a third cell using at least the second code and at least a third code, wherein values of the first code, the at least the second code, and the at least the third code may have a defined relationship. The third code may be a scrambling code or a basic midamble code. For some aspects, the first, second, and third cells may all correspond to the same Node B. For some aspects, values of the first code and the at least the second code may differ by an integer amount according to a defined relationship, and values of the at least the second code and the at least the third code may differ by the integer amount according to the defined relationship. For some aspects, there may be a defined relationship (e.g., the relationship illustrated in FIG. 7) between the first code, the at least the second code, and corresponding SYNC DL codes used by the Node B for communicating in the first and at least second cells.

[0055] Thus, according to certain aspects of the present disclosure, the Node B may transmit in multiple cells with SYNC DL/scrambling/midamble code allocation that allows for rapid identification of cells belonging to the same Node B, for example, based on searching for a small number of codes, such as scrambling or midamble codes. Negotiation of timing frames may be reduced or eliminated in some aspects. The Node B may provide for improved handover performance in certain aspects.

[0056] FIG. 10 illustrates searching for an intra-Node-B cell based on code allocation used in a three-cell Node B (e.g., the code allocation of FIG. 7 reproduced in table 1000 of FIG. 10) according to certain aspects of the present disclosure. During an initial search, if the UE identifies a scrambling code for a cell in the first 96 scrambling codes— for example, scrambling code = 3— it is likely that there exist some neighbor cells of the same Node B. Based on the code allocation rules above, the UE may perform a search 1002 for a cell with SYNC DL code = 8 or 16 and scrambling code = 35 or 67. By using this rule, the time spent searching available neighbor cells may be reduced. For other aspects, the code identified may be a midamble code, rather than a scrambling code. According to certain aspects, the code searched for may be a midamble code.

[0057] According to certain aspects of the present disclosure, there may be some benefits to knowing whether cells belong to the same Node B. One benefit is that handover may be facilitated. When there are multiple cells per Node B, and the UE performs handover to the target cell of the same Node B— i.e., intra-Node-B handover— it may be very easy to achieve the UL synchronization according to certain aspects. This is because the UE may be the same distance to the source and the target cells of the same Node B, and therefore, the UE may most likely use the current UL transmission timing of the source cell for the target cell. Accordingly, in some aspects of the present disclosure, there may be reduced time and/or resources needed to negotiate timing synchronization. In some aspects, there may be no need to negotiate timing synchronization. In some aspects, synchronization accuracy may be improved.

[0058] During handover, the source cell, which uses (for example) scrambling code = 35, may send the handover command (e.g., PHYSICAL CHANNEL RECONFIGURATION message) to the UE in which the cell parameter for the target cell is given, e.g., with scrambling or midamble code = 3. Then, the UE may know that the target cell belongs to the same Node B as the source cell. Because the target cell is associated with the same Node B as the source cell, the UE may use the same UL timing of the source cell to apply to the target cell, for example, in transmitting the UL synchronization code in hard handover or transmitting UL DPCH (Dedicated Physical Channel) in baton handover. According to certain aspects of the present disclosure, this may improve the UL synchronization accuracy and/or eliminate the initial UL synchronization procedure. Thus, according to certain aspects of the present disclosure, utilization of correspondence rules of SYNC DL/scrambling/midamble codes may allow recognition of the intra-Node-B cells and may improve handover performance.

[0059] Another benefit may be to reduce the latency in cell searches. Once the UE knows its current cell parameter (i.e., scrambling and/or midamble code), the UE may be able to determine a neighbor cell's parameter (scrambling code, midamble code, and/or SYNC DL codes) easily. Thus, searching for a neighbor cell may only require searching for the scrambling/midamble code of the neighbor. Therefore, the searching time and acquisition time of a neighbor cell may be shorter. [0060] In another configuration, the apparatus (e.g., the UE 350) for wireless communication includes means for obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code, and means for determining, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code. In one aspect, the aforementioned means may be the receive processor 370 or the controller/processor 390 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.

[0061] In one configuration, the apparatus (e.g., the Node B 310) for wireless communication includes means for communicating in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code, and means for communicating in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a first defined relationship. In one aspect, the aforementioned means may be the transmit processor 320 or the controller/processor 340 configured to perform the functions recited by the aforementioned means. In another aspect, the aforementioned means may be a module or any apparatus configured to perform the functions recited by the aforementioned means.

[0062] Several aspects of a telecommunications system have been presented with reference to a TD-SCDMA system. As those skilled in the art will readily appreciate, various aspects described throughout this disclosure may be extended to other telecommunication systems, network architectures and communication standards. By way of example, various aspects may be extended to other UMTS systems such as W- CDMA, High Speed Downlink Packet Access (HSDPA), High Speed Uplink Packet Access (HSUPA), High Speed Packet Access Plus (HSPA+) and TD-CDMA. Various aspects may also be extended to systems employing Long Term Evolution (LTE) (in FDD, TDD, or both modes), LTE-Advanced (LTE-A) (in FDD, TDD, or both modes), CDMA2000, Evolution-Data Optimized (EV-DO), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, Ultra- Wideband (UWB), Bluetooth, and/or other suitable systems. The actual telecommunication standard, network architecture, and/or communication standard employed will depend on the specific application and the overall design constraints imposed on the system.

[0063] Several processors have been described in connection with various apparatuses and methods. These processors may be implemented using electronic hardware, computer software, or any combination thereof. Whether such processors are implemented as hardware or software will depend upon the particular application and overall design constraints imposed on the system. By way of example, a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with a microprocessor, microcontroller, digital signal processor (DSP), a field-programmable gate array (FPGA), a programmable logic device (PLD), a state machine, gated logic, discrete hardware circuits, and other suitable processing components configured to perform the various functions described throughout this disclosure. The functionality of a processor, any portion of a processor, or any combination of processors presented in this disclosure may be implemented with software being executed by a microprocessor, microcontroller, DSP, or other suitable platform.

[0064] Software shall be construed broadly to mean instructions, instruction sets, code, code segments, program code, programs, subprograms, software modules, applications, software applications, software packages, routines, subroutines, objects, executables, threads of execution, procedures, functions, etc., whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise. The software may reside on a computer-readable medium. A computer- readable medium may include, by way of example, memory such as a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disc (CD), digital versatile disc (DVD)), a smart card, a flash memory device (e.g., card, stick, key drive), random access memory (RAM), read-only memory (ROM), programmable ROM (PROM), erasable PROM (EPROM), electrically erasable PROM (EEPROM), a register, or a removable disk. Although memory is shown separate from the processors in the various aspects presented throughout this disclosure, the memory may be internal to the processors (e.g., cache or register). [0065] Computer-readable media may be embodied in a computer-program product. By way of example, a computer-program product may include a computer-readable medium in packaging materials. Those skilled in the art will recognize how best to implement the described functionality presented throughout this disclosure depending on the particular application and the overall design constraints imposed on the overall system.

[0066] It is to be understood that the specific order or hierarchy of steps in the methods disclosed is an illustration of exemplary processes. Based upon design preferences, it is understood that the specific order or hierarchy of steps in the methods may be rearranged. The accompanying method claims present elements of the various steps in a sample order, and are not meant to be limited to the specific order or hierarchy presented unless specifically recited therein.

[0067] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims, wherein reference to an element in the singular is not intended to mean "one and only one" unless specifically so stated, but rather "one or more." Unless specifically stated otherwise, the term "some" refers to one or more. A phrase referring to "at least one of a list of items refers to any combination of those items, including single members. As an example, "at least one of: a, b, or c" is intended to cover: a; b; c; a and b; a and c; b and c; and a, b and c. All structural and functional equivalents to the elements of the various aspects described throughout this disclosure that are known or later come to be known to those of ordinary skill in the art are expressly incorporated herein by reference and are intended to be encompassed by the claims. Moreover, nothing disclosed herein is intended to be dedicated to the public regardless of whether such disclosure is explicitly recited in the claims. No claim element is to be construed under the provisions of 35 U.S.C. § 112, sixth paragraph, unless the element is expressly recited using the phrase "means for" or, in the case of a method claim, the element is recited using the phrase "step for."

[0068] WHAT IS CLAIMED IS:

Claims

1. A method for wireless communications, comprising:

obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and

determining, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code.

2. The method of claim 1, further comprising:

detecting a transmission from the second cell with the at least the second code; and

communicating in the second cell using the at least the second code.

3. The method of claim 2, wherein the first cell and the second cell are both associated with one Node B.

4. The method of claim 3, further comprising determining, based on the first code, that the Node B communicates in multiple cells.

5. The method of claim 3, further comprising:

communicating in the first cell using an uplink timing; and

performing a handover to the second cell, wherein communicating in the second cell comprises communicating in the second cell using the uplink timing.

6. The method of claim 2, wherein the first cell is associated with a first Node B and the second cell is associated with a second Node B.

7. The method of claim 1, further comprising determining, based on the first code, a downlink synchronization code (SYNC DL) used in the second cell.

8. An apparatus for wireless communications, comprising:

at least one processor configured to:

obtain a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and determine, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code; and

a memory coupled to the at least one processor.

9. The apparatus of claim 8, wherein the at least one processor is further configured to:

detect a transmission from the second cell with the at least the second code; and communicate in the second cell using the at least the second code.

10. The apparatus of claim 9, wherein the first cell and the second cell are both associated with one Node B.

11. The apparatus of claim 10, wherein the at least one processor is further configured to determine, based on the first code, that the Node B communicates in multiple cells.

12. The apparatus of claim 10, wherein the at least one processor is further configured to:

communicate in the first cell using an uplink timing; and

perform a handover to the second cell, wherein communicating in the second cell comprises communicating in the second cell using the uplink timing.

13. The apparatus of claim 9, wherein the first cell is associated with a first Node B and the second cell is associated with a second Node B.

14. The apparatus of claim 8, wherein the at least one processor is further configured to determine, based on the first code, a downlink synchronization (SYNC DL) code used in the second cell.

15. An apparatus for wireless communication comprising:

means for obtaining a first code used in a first cell, wherein the first code comprises a scrambling code or a basic midamble code; and

means for determining, based on the first code, at least a second code used in a second cell, wherein the at least the second code comprises a scrambling code or a basic midamble code.

16. The apparatus of claim 15, further comprising:

means for detecting a transmission from the second cell with the at least the second code; and

means for communicating in the second cell using the at least the second code.

17. The apparatus of claim 16, wherein the first cell and the second cell are both associated with one Node B.

18. The apparatus of claim 17, further comprising means for determining, based on the first code, that the Node B communicates in multiple cells.

19. The apparatus of claim 17, further comprising:

means for communicating in the first cell using an uplink timing; and

means for performing a handover to the second cell, wherein communicating in the second cell comprises communicating in the second cell using the uplink timing.

20. The apparatus of claim 16, wherein the first cell is associated with a first Node B and the second cell is associated with a second Node B.

21. The apparatus of claim 15, further comprising means for determining, based on the first code, a downlink synchronization (SYNC DL) code used in the second cell.

22. A computer-program product for wireless communications, the computer- program product comprising a computer-readable medium having code for:

23. The computer-program product of claim 22, wherein the computer-readable medium comprises code for:

communicating in the second cell using the at least the second code.

24. The computer-program product of claim 23, wherein the first cell and the second cell are both associated with one Node B.

25. The computer-program product of claim 24, wherein the computer-readable medium comprises code for determining, based on the first code, that the Node B communicates in multiple cells.

26. The computer-program product of claim 24, wherein the computer-readable medium comprises code for:

communicating in the first cell using an uplink timing; and

27. The computer-program product of claim 23, wherein the first cell is associated with a first Node B and the second cell is associated with a second Node B.

28. The computer-program product of claim 22, wherein the computer-readable medium comprises code for determining, based on the first code, a downlink

synchronization (SYNC DL) code used in the second cell.

29. A method for wireless communications by a Node B, comprising:

communicating in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code; and

communicating in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a first defined relationship.

30. The method of claim 29, wherein, according to the first defined relationship, values of the first code and the at least the second code differ by an integer amount.

31. The method of claim 30, wherein the integer amount comprises 2^N, wherein N is a positive integer.

32. The method of claim 29, wherein:

communicating in the at least the second cell using the at least the second code comprises communicating in the at least the second cell and at least a third cell using the at least the second code and at least a third code, wherein the third code comprises a scrambling code or a basic midamble code and values of the first code, the at least the second code, and the at least the third code have a second defined relationship; and according to the second defined relationship, the values of the first code and the at least the second code differ by an integer amount and the values of the at least the second code and the at least the third code differ by the integer amount.

33. The method of claim 29, wherein:

communicating in the first cell comprises communicating in the first cell using a downlink synchronization (SYNC DL) code;

communicating in the at least the second cell comprises communicating in the at least the second cell using the SYNC DL code; and

values of the first code, the at least the second code, and the SYNC DL code have a second defined relationship.

34. An apparatus for wireless communications by a Node B, comprising:

at least one processor configured to:

communicate in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code; and

communicate in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a first defined relationship; and

a memory coupled to the at least one processor.

35. The apparatus of claim 34, wherein, according to the first defined relationship, values of the first code and the at least the second code differ by an integer amount.

36. The apparatus of claim 35, wherein the integer amount comprises 2^N, wherein N is a positive integer.

37. The apparatus of claim 34, wherein:

the at least one processor is further configured to communicate in at least a third cell using at least a third code, wherein the at least the third code comprises a scrambling code or a basic midamble code and values of the first code, the at least the second code, and the at least the third code have a second defined relationship; and according to the second defined relationship, the values of the first code and the at least the second code differ by an integer amount and the values of the at least the second code and the at least the third code differ by the integer amount.

38. The apparatus of claim 34, wherein the at least one processor is further configured to:

communicate in the first cell using a downlink synchronization (SYNC DL) code; and

communicate in the at least the second cell using the SYNC DL code, wherein values of the first code, the at least the second code, and the SYNC DL code have a second defined relationship.

39. An apparatus for wireless communications by a Node B, comprising:

means for communicating in a first cell using a first code, wherein the first code comprises a scrambling code or a basic midamble code; and

means for communicating in at least a second cell using at least a second code, wherein the at least the second code comprises a scrambling code or a basic midamble code and values of the first code and the at least the second code have a first defined relationship.

40. The apparatus of claim 39, wherein, according to the first defined relationship, values of the first code and the at least the second code differ by an integer amount.

41. The apparatus of claim 40, wherein the integer amount comprises 2^N, wherein N is a positive integer.

42. The apparatus of claim 39, further comprising:

means for communicating in at least a third cell using at least a third code, wherein the at least the third code comprises a scrambling code or a basic midamble code and values of the first code, the at least the second code, and the at least the third code have a second defined relationship; and

wherein, according to the second defined relationship, the values of the first code and the at least the second code differ by an integer amount and the values of the at least the second code and the at least the third code differ by the integer amount.

43. The apparatus of claim 39, wherein:

the means for communicating in the first cell comprises means for

communicating in the first cell using a downlink synchronization (SYNC DL) code; the means for communicating in the at least the second cell comprises means for communicating in the at least the second cell using the SYNC DL code; and

44. A computer-program product for wireless communications by a Node B, comprising a computer-readable medium having code for:

45. The computer-program product of claim 44, wherein, according to the first defined relationship, values of the first code and the at least the second code differ by an integer amount.

46. The computer-program product of claim 45, wherein the integer amount comprises 2^N, wherein N is a positive integer.

47. The computer-program product of claim 44, wherein the computer-readable medium comprises code for:

communicating in at least a third cell using at least a third code, wherein the at least the third code comprises a scrambling code or a basic midamble code and values of the first code, the at least the second code, and the at least the third code have a second defined relationship; and

wherein, according to the second defined relationship, the values of the first code and the at least the second code differ by an integer amount and values of the at least the second code and the at least the third code differ by the integer amount.

48. The computer-program product of claim 44, wherein the computer-readable medium comprises code for:

communicating in the first cell using a downlink synchronization (SYNC DL) code; and

communicating in the at least the second cell using the SYNC DL code, wherein values of the first code, the at least the second code, and the SYNC DL code have a second defined relationship.