WO2014053077A1

WO2014053077A1 - Method and apparatus for time division synchronous (tds) code division multiple access (cdma) receive antenna diversity demodulations

Info

Publication number: WO2014053077A1
Application number: PCT/CN2012/082530
Authority: WO
Inventors: Wanlun Zhao; Qiang Shen; Insung Kang; Jilei Hou; Jinghu Chen
Original assignee: Qualcomm Incorporated
Priority date: 2012-10-06
Filing date: 2012-10-06
Publication date: 2014-04-10

Abstract

Apparatus and method for wireless communication in a wireless communication network that includes determining a cross antenna spatial weight, calculating an equivalent single antenna channel impulse response (CIR) and the equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial combing weight, and modeling an equivalent single antenna channel.

Description

METHOD AND APPARATUS FOR TIME DIVISION SYNCHRONOUS (TDS) CODE DIVISION MULTIPLE ACCESS (CDMA) RECEIVE ANTENNA

DIVERSITY DEMODULATIONS

BACKGROUND

Field

[0001] Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to an apparatus and method for reducing user equipment (UE) outages and enables spatial interference suppression gains for Time Division Synchronous Code Division Multiple Access systems.

Background

[0002] 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 UMTS 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 (3GPP). 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). The UMTS also supports enhanced 3G data communications protocols, such as High Speed Packet Access (HSPA), which provides higher data transfer speeds and capacity to associated UMTS networks.

[0003] In TDS-CDMA systems, receive antenna diversity (RxD) or having two or more

receiving (rx) antennas fosters considerable gains in spatial interference suppression and reduces outages due to deep fading in wireless channels. However, older first generation TDS-CDMA modems, receive antenna diversity is unavailable.

[0004] As such, to enable receive diversity, a low complexity RxD demodulation algorithm for a multiple antenna system is desirable and also must be designed to reuse many of the single receive antenna design blocks. This design may also achieve large performance improvements over single antenna designs, especially for fading channels. [0005] Thus, aspects of this an apparatus and method include reducing user equipment

(UE) outages and enables spatial interference suppression gains for Time Division Synchronous (TDS) Code Division Multiple Access (CDMA) systems.

BRIEF DESCRIPTION OF THE DRAWINGS

[0006] FIG. 1 is a schematic diagram illustrating exemplary aspect of antenna in a wireless communication system;

[0007] FIG. 2 is a schematic diagram illustrating the functionally and operation of the traffic demodulation component in a wireless communication system;

[0008] Fig. 3 is a schematic diagram illustrating the utilization of modifying existing micro-kernels of current single antenna LMUD design.

[0009] FIG. 4 is a flow diagram illustrating an exemplary method for antenna processing in a wireless communication system;

[0010] FIG. 5 is a block diagram illustrating an example of a hardware implementation for an apparatus employing a processing system to perform the functions described herein;

[0011] FIG. 6 is a block diagram conceptually illustrating an example of a telecommunications system including a UE configured to perform the functions described herein;

[0012] FIG. 7 is a conceptual diagram illustrating an example of an access network for use with a UE configured to perform the functions described herein;

[0013] FIG. 8 is a conceptual diagram illustrating an example of a radio protocol architecture for the user and control planes for a base station and/or a UE configured to perform the functions described herein;

[0014] FIG. 9 is a block diagram conceptually illustrating an example of a Node B in communication with a UE in a telecommunications system configured to perform the functions described herein.

DETAILED DESCRIPTION

[0015] 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 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.

[0016] As discussed above, aspects of this apparatus and method include a low complexity receive diversity demodulation algorithm, named spatial combining linear multi-user detection (SC-LMUD), that is designed for a multiple antenna system and designed to reuse many of the single receive antenna design blocks. Not only does this achieve large performance improvements over single antenna designs, especially for fading channels, this design enables relatively simple modifications on single antenna designs. Along with lower algorithm complexity, the SC-LMUD design is also robust enough for different Walsh domain structures. Additionally, the SC-LMUD design achieves large diversity gains and spatial interference suppression gains over single antenna.

[0017] Referring to Fig. 1, in one aspect of the present apparatus and method, a wireless communication system 10 is configured to include wireless communications between network 12 and user equipment (UE) 14. The wireless communications system may be configured to support communications between a number of users. Fig. 1 illustrates a manner in which network 12 communicates with UE 14. The wireless communication system 10 can be configured for downlink message transmission or uplink message transmission, as represented by the up/down arrows between network 12 and UE 14.

[0018] In an aspect, within the UE 14 resides an antenna processing component 40.

The antenna processing component 40 may be configured, among other things, to include a weight determining component 42 capable of determining a cross antenna spatial weight based on combining a scalar weight of the a first antenna and a scalar weight of a second antenna. In other words, the weight determining component 42 is configured to combine the scalar weight of the first antenna with the scalar weight of the second antenna thereby determining the cross antenna spatial combing weight.

[0019] There are several options to perform cross antenna spatial combining. For example, by ignoring all Walsh domain structures, a per frequency tone based LMMSE cross antenna spatial combining may be performed. This has the added bonus of being locally optimal. However, such a locally optimal cross antenna combining does not always lead to better overall performance, when followed by single antenna LMUD.

[0020] For this reason, the focus will be on a simpler spatial combining scheme, which is flat in frequency domain. That is, under the flat constraint, only a suitable 2x1 cross antenna combining vector needs be determined, since each antenna has a single scalar weight under a flat constraint.

[0021] Specifically, the strongest path from each receive antenna based on serving cell' s CIR is determined. To accomplish this, first denote the strongest path coefficients and their corres ondin delay by the following .

[0023] Here, ho and hi are complex scalar coefficients, r₀ and τ_ι are potentially different integer chip delays. Conceptually, the combining between these 2 paths is similar to Rake finger combining.

[0024] Subsequently, perform a normalized 2x2 mimimum mean square error (MMSE) combining is performed. Achieving MMSE means the receiver will achieve linear optimality. For this purpose, a 2x2 covariance matrix in the following form is computed.

[0026] To compute entries of R, the following vector model is considered and applied.

K-l

-I ® (c* ° wj] - s_t + n_m , m

[0027]

[0028] Where m is the receive antenna index, H is a MQxMQ channel matrix; s is the transmitted symbol vector, w and c are 16x1 Walsh channel vector and short scrambling code, respectively, / is the MxM identity matrix, and n is the AWGN noise vector with dimension MQxl . Note, the noise is assumed to have 0 mean and some covariance matrix.

[0029] Since R₀o and R_n are simply the received averaged chip energy from antennas 0 and 1, respectively, they can be computed by: m = 0, 1

Assuming that entries of the short scrambling sequences are independent and random with zero mean and unit variances, this results in:

[0033] Now, if the first column of H_{m (}t is denoted by h_m>k, the following simpler expression is resulted.

[0035] Where \\ h_{m k} II denotes the vector norm of h_{m k} . Here, emphasize is placed on the

assumption that the short scrambling sequences are random which enables considerable simplifications on the derivations. However, the scrambling codes for a few strong cell are deterministically known. Hence, they are not really random variables but since they are treated as deterministic, the averaged chip energy will be different for 16 chips within a symbol.

[0036] For the cross antenna term Roi, a permutation matrix P_T is introduced, which cyclically shifts columns of H_{1 k} based on the delay difference τ₀ - τ_λ . This permutation ensures the strongest path from antenna 0 and 1 are time aligned. Mathematically, this results in:

[0038] Here, _{l k T} denotes the cyclically shifted first column ofH_{l k} . Here, it can be observed that a need arises to compute several 16x1 vector inner products for R₀i.

[0039] After determining all the needed components, the final spatial combining weights is computed by:

[0040] [« fi = ^HR "

[0041] As described in the above, r₀ and τ_χ represent positions of the paths with highest power for Rx antenna 0 and 1, respectively. In most practical scenarios, however, channel delay profiles of the two rx antennas are quite similar. Statistically, it is better to limit the range of time difference between r₀ and r_jin terms of chips.

[0042] Based on simulation studies, aspects of this apparatus and method are configured to

propose the following modifications on path alignment: [0043] a.) For the midamble (dedicated pilot sequence) shift of serving CIR, calculate power of all 16 paths for each antenna;

[0044] b.) Denote the strongest path position by r_max , which can be either r₀ or τ_χ , depending on whether that strongest path belongs to antenna 0 or 1;

[0045] c.) Search the otherl 6-path CIR for the strongest path under the following position constraint:

[0046] £€ Cfrwe* - masOfSsi, Ϊ_ΚΪ≤¾:, 4- msxOf&ei] Π [0,!¾} [0047] Here, masOffset £ [¾I ¾ is an input integer parameter;

[0048] d.) Denote the constrained strongest path position determined in step 3 by either r₀ or τ_ι depending on which antenna this path belongs to;

[0049] e.) The path difference t_i— ?_>3 is used to shift Rxl CIR paths to align two antenna's

CIRs. It will also be used in data sample combining to form equivalent single antenna samples.

[0050] Note with this approach, Rxl CIR and samples are shifted on either direction by no more than max Offset chips. RxO CIR is never shifted, even though it could be the weaker antenna.

[0051] Moreover, in the spatial combining stage of SC-LMUD, interfering cells are assumed to not have any Walsh domain structures. That is, in the SC stage, the focus is on spatial interference suppressions. This can lead to performance degradations when interfering cells are actually highly structured in Walsh domain.

[0052] To enable a robust design to various Walsh domain interference structures thereby

improving performance, aspects of this apparatus and method are configured to propose the following modification:

[0053] R = R + c - trace - I

[0054] Where, R is the 2x2 covariance matrix, c is a scalar constant, trace is the trace of matrix

R; and finally, I is the 2x2 identity matrix.

[0055] The benefit of this modification is 2 folded: It makes SC-LMUD robust to interference

Walsh loading and improves the numerical stability when R matrix is inverted. When R matrix is near singular, computing inverted R is numerically challenging. With this modification, however, R is guaranteed to be good conditioned. [0056] The antenna processing component 40 may also be configured to include a calculation component 44 capable calculating an equivalent single antenna channel impulse response (CIR) and the equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial combing weight. Afterwards, antenna processing component 40 may be configured to include a modeling component 36 capable of modeling an equivalent single antenna receiving channel.

[0057] Specifically, the calculation component 44 and modeling component 36 are configured in such a fashion as to combine two receive antenna channels into a single set of equivalent channels. In this manner, reuse of single antenna parametric LMUD designs.

[0058] The calculation component 44 and modeling component 36 are capable of forming the following set of equivalent single antenna channel vectors based on the individually estimated channel coefficients and calculated 2x1 cross antenna combining vector.

[0060] Note, the time shifted channel vector for antenna 1 is utilized in the above equation.

[0061] Furthermore, the calculation component 44 and modeling component 36 determines the equivalent single antenna noise variance by the computation:

n\²

[0062] ^{σ =} \^a\ ^{' σ}« ⁺ \^β\ ^{- CJl}

[0063] The antenna processing component 40 may also be configured to include a traffic demodulation component 48. Aspects of the traffic demodulation component 48 may be configured to compute an equivalent single antenna LMUD weight, form equivalent single antenna traffic sample, and apply the equivalent single antenna LMUD weight to the equivalent single antenna traffic sample to obtain chip level estimates of the transmitted chips. Last, after dispreading and removing Walsh covers, estimates of the transmitted chips will be obtained. The specifics components of the traffic demodulation component 48 are further elaborated upon in Fig. 2.

[0064] Thus, the present apparatus and methods improve the ability of a UE to achieve reduction of UE outages and enables spatial interference suppression gains for Time Division Synchronous Code Division Multiple Access systems.

[0065] Fig. 2 is a schematic diagram 50 further illustrating the functionally and operation of the traffic demodulation component 48 that resides in the antenna processing component 40 (Fig. 1). Specifically, LMUD component 52 residing in the traffic demodulation component 48 is configured to calculate an equivalent single antenna LMUD weight based on the equivalent single antenna channel coefficients. [0066] Moreover, residing the traffic demodulation component 48, there is a traffic sample component 54 for calculating and determining the traffic sample for the first antenna 55, the second antenna 56, and the equivalent single antenna 57. Indeed, the traffic sample component 54 is configured to combine traffic samples received on the first antenna and the second antenna to form an equivalent single antenna traffic sample.

[0067] After determining the traffic samples received on the first antenna and the second antenna, the traffic demodulation component 48 is configured to apply the equivalent single antenna LMUD weight to the equivalent single antenna traffic sample to obtain chip level estimates of the transmitted chips.

[0068] To calculate the equivalent single antenna LMUD weight, the LMUD coefficient matrix based on the equivalent single antenna channel is denoted by:

[0069] T = H^HR^

[0070] Here, R is constructed based on equivalent single antenna channel coefficients and the serving cell's effective channel matrix is:

[0071] Η = α · Η₀ +β- Η_ι

[0072] To form the equivalent single antenna traffic sample by combining traffic samples from both rx antennas, the following combination is calculated:

[0073] ν = α · γ₀ + β · Ρ_τ · γ_ι

p

[0074] Where ^T is a permutation matrix that the addresses the time adjustment for antenna 1. In real implementations, chip samples from antenna 1 based on the time difference ?_x— τ_δ may be shifted.

[0075] Last, the final chip estimation of applying the equivalent single antenna LMUD weight to the equivalent single antenna traffic sample can be generated by:

[0076]

[0077] Fig. 3 is a schematic diagram 60 illustrating aspects of this apparatus and method that illustrates the utilization of modifying existing design blocks of current single antenna LMUD design. As alluded to earlier, one of the main advantages of the SC-LMUD algorithm and design involves the reuse of existing key design blocks from single antenna LMUD design. However, since SC-LMUD also includes antenna selection LMUD weighting and processing, existing design blocks must be modified.

[0078] Specifically regarding the elements of Fig. 3, elements 61-66 represent the existing design blocks of previous single antenna LMUD design. Elements 67 and 68 represent the new design blocks needed for the SC-LMUD algorithm and design. Element 69 represents the modified EWC design block based on the newly added elements 67-68 of SC-LMUD design to the existing design blocks of the single antenna LMUD design. Note, the design blocks and elements of Fig. 3 may be configured to be implemented in the antenna processing component 40 of Fig. 1.

[0079] Fig. 4 is a flow diagram illustrating an exemplary method 70. At 72, the UE determines a cross antenna spatial weight based on combining a scalar weight of a first antenna and a scalar weight of a second antenna. Calculating an equivalent single antenna channel impulse response (CIR) and the equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial combing weight occurs at 73. Additionally, at 74, the UE models an equivalent single antenna channel.

[0080] Optionally, at 75, the UE calculates an equivalent single antenna LMUD weight based on the equivalent single antenna channel coefficients. Combining traffic samples received on the first antenna and the second antenna to form an equivalent single antenna traffic sample, optionally occurs at 76. Last, at 77, the UE applies the equivalent single antenna LMUD weight to the equivalent single antenna traffic sample to generate transmitted chip level estimates.

[0081] In an aspect, for example, the UE executing method 70 may be UE 14 (Fig. 1) executing the antenna processing component 40 (Fig. 1), or respective components thereof.

[0082] Fig. 5 is a block diagram illustrating an example of a hardware implementation for an apparatus 100 employing a processing system 114 for performing the processing and decoding of data, as described herein. In this example, the processing system 114 may be implemented with a bus architecture, represented generally by the bus 102. The bus 102 may include any number of interconnecting buses and bridges depending on the specific application of the processing system 114 and the overall design constraints. The bus 102 links together various circuits including one or more processors, represented generally by the processor 104, and computer-readable media, represented generally by the computer-readable medium 106. The bus 102 may also link various other circuits such as timing sources, peripherals, voltage regulators, and power management circuits, which are well known in the art, and therefore, will not be described any further. A bus interface 108 provides an interface between the bus 102 and a transceiver 110. The transceiver 110 provides a means for communicating with various other apparatus over a transmission medium. Depending upon the nature of the apparatus, a user interface 112 (e.g., keypad, display, speaker, microphone, joystick) may also be provided.

[0083] The processor 104 is responsible for managing the bus 102 and general processing, including the execution of software stored on the computer-readable medium 106. The software, when executed by the processor 104, causes the processing system 114 to perform the various functions described infra for any particular apparatus. The computer-readable medium 106 may also be used for storing data that is manipulated by the processor 104 when executing software.

[0084] In an aspect, processor 104, computer-readable medium 106, or a combination of both may be configured or otherwise specially programmed to perform the functionality of the antenna component 40 (Fig. 1) as described herein.

[0085] The various concepts presented throughout this disclosure may be implemented across a broad variety of telecommunication systems, network architectures, and communication standards.

[0086] Referring to Fig. 6, by way of example and without limitation, the aspects of the present disclosure are presented with reference to a UMTS system 200 employing a W- CDMA air interface. A UMTS network includes three interacting domains: a Core Network (CN) 204, a UMTS Terrestrial Radio Access Network (UTRAN) 202, and User Equipment (UE) 210. UE 210 may be configured to include, for example, the antenna component 40 (Fig. 1) as described above. In this example, the UTRAN 202 provides various wireless services including telephony, video, data, messaging, broadcasts, and/or other services. The UTRAN 202 may include a plurality of Radio Network Subsystems (RNSs) such as an RNS 207, each controlled by a respective Radio Network Controller (RNC) such as an RNC 206. Here, the UTRAN 202 may include any number of RNCs 206 and RNSs 207 in addition to the RNCs 206 and RNSs 207 illustrated herein. The RNC 206 is an apparatus responsible for, among other things, assigning, reconfiguring and releasing radio resources within the RNS 207. The RNC 206 may be interconnected to other RNCs (not shown) in the UTRAN 202 through various types of interfaces such as a direct physical connection, a virtual network, or the like, using any suitable transport network.

[0087] Communication between a UE 210 and a Node B 208 may be considered as including a physical (PHY) layer and a medium access control (MAC) layer. Further, communication between a UE 210 and an RNC 206 by way of a respective Node B 208 may be considered as including a radio resource control (RRC) layer. In the instant specification, the PHY layer may be considered layer 1; the MAC layer may be considered layer 2; and the RRC layer may be considered layer 3. Information hereinbelow utilizes terminology introduced in the RRC Protocol Specification, 3GPP TS 25.331, incorporated herein by reference.

[0088] The geographic region covered by the RNS 207 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, three Node Bs 208 are shown in each RNS 207; however, the RNSs 207 may include any number of wireless Node Bs. The Node Bs 208 provide wireless access points to a CN 204 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 a UE in UMTS applications, but may also be referred to by those skilled in the art as a mobile station, 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, 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. In a UMTS system, the UE 210 may further include a universal subscriber identity module (USIM) 211, which contains a user's subscription information to a network. For illustrative purposes, one UE 210 is shown in communication with a number of the Node Bs 208. The DL, also called the forward link, refers to the communication link from a Node B 208 to a UE 210, and the UL, also called the reverse link, refers to the communication link from a UE 210 to a Node B 208.

[0089] The CN 204 interfaces with one or more access networks, such as the UTRAN

202. As shown, the CN 204 is 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 CNs other than GSM networks.

[0090] The CN 204 includes a circuit- switched (CS) domain and a packet-switched (PS) domain. Some of the circuit- switched elements are a Mobile services Switching Centre (MSC), a Visitor location register (VLR) and a Gateway MSC. Packet- switched elements include a Serving GPRS Support Node (SGSN) and a Gateway GPRS Support Node (GGSN). Some network elements, like EIR, HLR, VLR and AuC may be shared by both of the circuit- switched and packet-switched domains. In the illustrated example, the CN 204 supports circuit- switched services with a MSC 212 and a GMSC 214. In some applications, the GMSC 214 may be referred to as a media gateway (MGW). One or more RNCs, such as the RNC 206, may be connected to the MSC 212. The MSC 212 is an apparatus that controls call setup, call routing, and UE mobility functions. The MSC 212 also includes a VLR that contains subscriber-related information for the duration that a UE is in the coverage area of the MSC 212. The GMSC 214 provides a gateway through the MSC 212 for the UE to access a circuit- switched network 216. The GMSC 214 includes a home location register (HLR) 215 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 214 queries the HLR 215 to determine the UE's location and forwards the call to the particular MSC serving that location.

[0091] The CN 204 also supports packet-data services with a serving GPRS support node (SGSN) 218 and a gateway GPRS support node (GGSN) 220. GPRS, which stands for General Packet Radio Service, is designed to provide packet-data services at speeds higher than those available with standard circuit-switched data services. The GGSN 220 provides a connection for the UTRAN 202 to a packet-based network 222. The packet-based network 222 may be the Internet, a private data network, or some other suitable packet-based network. The primary function of the GGSN 220 is to provide the UEs 210 with packet-based network connectivity. Data packets may be transferred between the GGSN 220 and the UEs 210 through the SGSN 218, which performs primarily the same functions in the packet-based domain as the MSC 212 performs in the circuit- switched domain.

[0092] An air interface for UMTS may utilize a spread spectrum Direct-Sequence Code

Division Multiple Access (DS-CDMA) system. The spread spectrum DS-CDMA spreads user data through multiplication by a sequence of pseudorandom bits called chips. The "wideband" W-CDMA air interface for UMTS is based on such direct sequence spread spectrum technology and additionally calls for a frequency division duplexing (FDD). FDD uses a different carrier frequency for the UL and DL between a Node B 208 and a UE 210. Another air interface for UMTS that utilizes DS-CDMA, and uses time division duplexing (TDD), is the TD-SCDMA air interface. Those skilled in the art will recognize that although various examples described herein may refer to a W-CDMA air interface, the underlying principles may be equally applicable to a TD- SCDMA air interface.

[0093] An HSPA air interface includes a series of enhancements to the 3G/W-CDMA air interface, facilitating greater throughput and reduced latency. Among other modifications over prior releases, HSPA utilizes hybrid automatic repeat request (HARQ), shared channel transmission, and adaptive modulation and coding. The standards that define HSPA include HSDPA (high speed downlink packet access) and HSUPA (high speed uplink packet access, also referred to as enhanced uplink, or EUL).

[0094] HSDPA utilizes as its transport channel the high-speed downlink shared channel

(HS-DSCH). The HS-DSCH is implemented by three physical channels: the high-speed physical downlink shared channel (HS-PDSCH), the high-speed shared control channel (HS-SCCH), and the high-speed dedicated physical control channel (HS-DPCCH).

[0095] Among these physical channels, the HS-DPCCH carries the HARQ

ACK/NACK signaling on the uplink to indicate whether a corresponding packet transmission was decoded successfully. That is, with respect to the downlink, the UE 210 provides feedback to the node B 208 over the HS-DPCCH to indicate whether it correctly decoded a packet on the downlink.

[0096] HS-DPCCH further includes feedback signaling from the UE 210 to assist the node B 208 in taking the right decision in terms of modulation and coding scheme and precoding weight selection, this feedback signaling including the CQI and PCI.

[0097] "HSPA Evolved" or HSPA+ is an evolution of the HSPA standard that includes

MIMO and 64-QAM, enabling increased throughput and higher performance. That is, in an aspect of the disclosure, the node B 208 and/or the UE 210 may have multiple antennas supporting MIMO technology. The use of MIMO technology enables the node B 208 to exploit the spatial domain to support spatial multiplexing, beamforming, and transmit diversity. [0098] Multiple Input Multiple Output (MIMO) is a term generally used to refer to multi-antenna technology, that is, multiple transmit antennas (multiple inputs to the channel) and multiple receive antennas (multiple outputs from the channel). MIMO systems generally enhance data transmission performance, enabling diversity gains to reduce multipath fading and increase transmission quality, and spatial multiplexing gains to increase data throughput.

[0099] Spatial multiplexing may be used to transmit different streams of data simultaneously on the same frequency. The data steams may be transmitted to a single UE 210 to increase the data rate, or to multiple UEs 210 to increase the overall system capacity. This is achieved by spatially precoding each data stream and then transmitting each spatially precoded stream through a different transmit antenna on the downlink. The spatially precoded data streams arrive at the UE(s) 210 with different spatial signatures, which enables each of the UE(s) 210 to recover the one or more the data streams destined for that UE 210. On the uplink, each UE 210 may transmit one or more spatially precoded data streams, which enables the node B 208 to identify the source of each spatially precoded data stream.

[00100] Spatial multiplexing may be used when channel conditions are good. When channel conditions are less favorable, beamforming may be used to focus the transmission energy in one or more directions, or to improve transmission based on characteristics of the channel. This may be achieved by spatially precoding a data stream for transmission through multiple antennas. To achieve good coverage at the edges of the cell, a single stream beamforming transmission may be used in combination with transmit diversity.

[00101] Generally, for MIMO systems utilizing n transmit antennas, n transport blocks may be transmitted simultaneously over the same carrier utilizing the same channelization code. Note that the different transport blocks sent over the n transmit antennas may have the same or different modulation and coding schemes from one another.

[00102] On the other hand, Single Input Multiple Output (SIMO) generally refers to a system utilizing a single transmit antenna (a single input to the channel) and multiple receive antennas (multiple outputs from the channel). Thus, in a SIMO system, a single transport block is sent over the respective carrier.

[00103] Referring to Fig. 7, an access network 300 in a UTRAN architecture is illustrated. The multiple access wireless communication system includes multiple cellular regions (cells), including cells 302, 304, and 306, each of which may include one or more sectors. The multiple sectors can be formed by groups of antennas with each antenna responsible for communication with UEs in a portion of the cell. For example, in cell 302, antenna groups 312, 314, and 316 may each correspond to a different sector. In cell 304, antenna groups 318, 320, and 322 each correspond to a different sector. In cell 306, antenna groups 324, 326, and 328 each correspond to a different sector. The cells 302, 304 and 306 may include several wireless communication devices, e.g., User Equipment or UEs, which may be in communication with one or more sectors of each cell 302, 304 or 306. For example, UEs 330 and 332 may be in communication with Node B 342, UEs 334 and 336 may be in communication with Node B 344, and UEs 338 and 340 can be in communication with Node B 346. Here, each Node B 342, 344, 346 is configured to provide an access point to a CN 204 (see FIG. 2) for all the UEs 330, 332, 334, 336, 338, 340 in the respective cells 302, 304, and 306. Node Bs 342, 344, 346 and UEs 330, 332, 334, 336, 338, 340 respectively may be configured to include, for example, the antenna component 40 (Fig. 1) as described above.

[00104] As the UE 334 moves from the illustrated location in cell 304 into cell 306, a serving cell change (SCC) or handover may occur in which communication with the UE 334 transitions from the cell 304, which may be referred to as the source cell, to cell 306, which may be referred to as the target cell. Management of the handover procedure may take place at the UE 334, at the Node Bs corresponding to the respective cells, at a radio network controller 206 (see FIG. 2), or at another suitable node in the wireless network. For example, during a call with the source cell 304, or at any other time, the UE 334 may monitor various parameters of the source cell 304 as well as various parameters of neighboring cells such as cells 306 and 302. Further, depending on the quality of these parameters, the UE 334 may maintain communication with one or more of the neighboring cells. During this time, the UE 334 may maintain an Active Set, that is, a list of cells that the UE 334 is simultaneously connected to (i.e., the UTRA cells that are currently assigning a downlink dedicated physical channel DPCH or fractional downlink dedicated physical channel F-DPCH to the UE 334 may constitute the Active Set).

[00105] The modulation and multiple access scheme employed by the access network

300 may vary depending on the particular telecommunications standard being deployed. By way of example, the standard may include Evolution-Data Optimized (EV-DO) or Ultra Mobile Broadband (UMB). EV-DO and UMB are air interface standards promulgated by the 3rd Generation Partnership Project 2 (3GPP2) as part of the CDMA2000 family of standards and employs CDMA to provide broadband Internet access to mobile stations. The standard may alternately be Universal Terrestrial Radio Access (UTRA) employing Wideband-CDMA (W-CDMA) and other variants of CDMA, such as TD-SCDMA; Global System for Mobile Communications (GSM) employing TDM A; and Evolved UTRA (E-UTRA), Ultra Mobile Broadband (UMB), IEEE 802.11 (Wi-Fi), IEEE 802.16 (WiMAX), IEEE 802.20, and Flash-OFDM employing OFDM A. UTRA, E-UTRA, UMTS, LTE, LTE Advanced, and GSM are described in documents from the 3GPP organization. CDMA2000 and UMB are described in documents from the 3GPP2 organization. The actual wireless communication standard and the multiple access technology employed will depend on the specific application and the overall design constraints imposed on the system.

[00106] The radio protocol architecture may take on various forms depending on the particular application. An example for an HSPA system will now be presented with reference to Fig. 8.

[00107] Fig. 8 is a conceptual diagram illustrating an example of the radio protocol architecture 400 for the user plane 402 and the control plane 404 of a user equipment (UE) or node B/base station. For example, architecture 400 may be included in a network entity and/or UE such as an entity within wireless network 12 and/or UE14 (Fig. 1). The radio protocol architecture 400 for the UE and node B is shown with three layers: Layer 1 406, Layer 2 408, and Layer 3 410. Layer 1 406 is the lowest lower and implements various physical layer signal processing functions. As such, Layer 1 406 includes the physical layer 407. Layer 2 (L2 layer) 408 is above the physical layer 407 and is responsible for the link between the UE and node B over the physical layer 407. Layer 3 (L3 layer) 410 includes a radio resource control (RRC) sublayer 415. The RRC sublayer 415 handles the control plane signaling of Layer 3 between the UE and the UTRAN.

[00108] In the user plane, the L2 layer 408 includes a media access control (MAC) sublayer 409, a radio link control (RLC) sublayer 411, and a packet data convergence protocol (PDCP) 413 sublayer, which are terminated at the node B on the network side. Although not shown, the UE may have several upper layers above the L2 layer 408 including a network layer (e.g., IP layer) that is terminated at a PDN gateway on the network side, and an application layer that is terminated at the other end of the connection (e.g., far end UE, server, etc.).

[00109] The PDCP sublayer 413 provides multiplexing between different radio bearers and logical channels. The PDCP sublayer 413 also provides header compression for upper layer data packets to reduce radio transmission overhead, security by ciphering the data packets, and handover support for UEs between node Bs. The RLC sublayer 411 provides segmentation and reassembly of upper layer data packets, retransmission of lost data packets, and reordering of data packets to compensate for out-of-order reception due to hybrid automatic repeat request (HARQ). The MAC sublayer 409 provides multiplexing between logical and transport channels. The MAC sublayer 409 is also responsible for allocating the various radio resources (e.g., resource blocks) in one cell among the UEs. The MAC sublayer 409 is also responsible for HARQ operations.

[00110] Fig. 9 is a block diagram of a communication system 500 including a Node B

510 in communication with a UE 550, where Node B 510 may be an entity within wireless network 12 and the UE 550 may be UE 14 according to the aspect described in Fig. 1. In the downlink communication, a transmit processor 520 may receive data from a data source 512 and control signals from a controller/processor 540. The transmit processor 520 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 520 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 544 may be used by a controller/processor 540 to determine the coding, modulation, spreading, and/or scrambling schemes for the transmit processor 520. These channel estimates may be derived from a reference signal transmitted by the UE 550 or from feedback from the UE 550. The symbols generated by the transmit processor 520 are provided to a transmit frame processor 530 to create a frame structure. The transmit frame processor 530 creates this frame structure by multiplexing the symbols with information from the controller/processor 540, resulting in a series of frames. The frames are then provided to a transmitter 532, which provides various signal conditioning functions including amplifying, filtering, and modulating the frames onto a carrier for downlink transmission over the wireless medium through antenna 534. The antenna 534 may include one or more antennas, for example, including beam steering bidirectional adaptive antenna arrays or other similar beam technologies.

[00111] At the UE 550, a receiver 554 receives the downlink transmission through an antenna 552 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 554 is provided to a receive frame processor 560, which parses each frame, and provides information from the frames to a channel processor 594 and the data, control, and reference signals to a receive processor 570. The receive processor 570 then performs the inverse of the processing performed by the transmit processor 520 in the Node B 510. More specifically, the receive processor 570 descrambles and despreads the symbols, and then determines the most likely signal constellation points transmitted by the Node B 510 based on the modulation scheme. These soft decisions may be based on channel estimates computed by the channel processor 594. 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 572, which represents applications running in the UE 550 and/or various user interfaces (e.g., display). Control signals carried by successfully decoded frames will be provided to a controller/processor 590. When frames are unsuccessfully decoded by the receiver processor 570, the controller/processor 590 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[00112] In the uplink, data from a data source 578 and control signals from the controller/processor 590 are provided to a transmit processor 580. The data source 578 may represent applications running in the UE 550 and various user interfaces (e.g., keyboard). Similar to the functionality described in connection with the downlink transmission by the Node B 510, the transmit processor 580 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 594 from a reference signal transmitted by the Node B 510 or from feedback contained in the midamble transmitted by the Node B 510, may be used to select the appropriate coding, modulation, spreading, and/or scrambling schemes. The symbols produced by the transmit processor 580 will be provided to a transmit frame processor 582 to create a frame structure. The transmit frame processor 582 creates this frame structure by multiplexing the symbols with information from the controller/processor 590, resulting in a series of frames. The frames are then provided to a transmitter 556, 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 552.

[00113] The uplink transmission is processed at the Node B 510 in a manner similar to that described in connection with the receiver function at the UE 550. A receiver 535 receives the uplink transmission through the antenna 534 and processes the transmission to recover the information modulated onto the carrier. The information recovered by the receiver 535 is provided to a receive frame processor 536, which parses each frame, and provides information from the frames to the channel processor 544 and the data, control, and reference signals to a receive processor 538. The receive processor 538 performs the inverse of the processing performed by the transmit processor 580 in the UE 550. The data and control signals carried by the successfully decoded frames may then be provided to a data sink 539 and the controller/processor, respectively. If some of the frames were unsuccessfully decoded by the receive processor, the controller/processor 540 may also use an acknowledgement (ACK) and/or negative acknowledgement (NACK) protocol to support retransmission requests for those frames.

[00114] The controller/processors 540 and 590 may be used to direct the operation at the

Node B 510 and the UE 550, respectively. For example, the controller/processors 540 and 590 may provide various functions including timing, peripheral interfaces, voltage regulation, power management, and other control functions. The computer readable media of memories 542 and 592 may store data and software for the Node B 510 and the UE 550, respectively. A scheduler/processor 546 at the Node B 510 may be used to allocate resources to the UEs and schedule downlink and/or uplink transmissions for the UEs.

[00115] Several aspects of a telecommunications system have been presented with reference to a W-CDMA 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. [00116] By way of example, various aspects may be extended to other UMTS systems such as TD-SCDMA, 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.

[00117] In accordance with various aspects of the disclosure, an element, or any portion of an element, or any combination of elements may be implemented with a "processing system" that includes one or more processors. Examples of processors include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), state machines, gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. One or more processors in the processing system may execute software. 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. The computer-readable medium may be a non-transitory computer-readable medium. A non-transitory computer-readable medium includes, by way of example, a magnetic storage device (e.g., hard disk, floppy disk, magnetic strip), an optical disk (e.g., compact disk (CD), digital versatile disk (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, a removable disk, and any other suitable medium for storing software and/or instructions that may be accessed and read by a computer. The computer-readable medium may also include, by way of example, a carrier wave, a transmission line, and any other suitable medium for transmitting software and/or instructions that may be accessed and read by a computer. The computer-readable medium may be resident in the processing system, external to the processing system, or distributed across multiple entities including the processing system. The computer- readable medium 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.

[00118] 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.

[00119] The previous description is provided to enable any person skilled in the art to practice the various aspects described herein. Various modifications to these aspects will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other aspects. Thus, the claims are not intended to be limited to the aspects shown herein, but is to be accorded the full scope consistent with the language 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."

Claims

CLAIMS What is claimed is:

1. A method for wireless communication, comprising:

determining a cross antenna spatial weight based on combining a scalar weight of the a first antenna and a scalar weight of a second antenna;

calculating an equivalent single antenna channel impulse response (CIR) and a equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial weight;

modeling an equivalent single antenna channel.

2. The method of claim 1, further comprising:

calculating an equivalent single antenna linear multi-user detection (LMUD) weight based on the equivalent single antenna channel coefficients;

combining traffic samples received on the first antenna and the second antenna to form an equivalent single antenna traffic sample;

applying the equivalent single antenna LMUD weight to the equivalent single antenna traffic sample to generate transmitted chip level estimates.

3. The method of claim 1, wherein modeling the equivalent single antenna channel is performed under a flat frequency domain constraint.

4. The method of claim 1, wherein the equivalent single antenna channel robustness is improved based on utilizing a covariance inversion.

5. The method of claim 4, wherein numerical stability of the equivalent single antenna channel is improved based on utilizing the covariance inversion.

6. An apparatus of wireless communication in a wireless communication network, comprising:

means for determining a cross antenna spatial weight based on combining a scalar weight of the a first antenna and a scalar weight of a second antenna; means for calculating an equivalent single antenna CIR and an equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial weight;

means for modeling an equivalent single antenna channel.

7. The apparatus of claim 6, further comprising means for performing the functions of any of claims 2 or 3 or 4 or 5.

8. A computer program product, comprising:

a computer readable medium comprising code for:

calculating an equivalent single antenna CIR and an equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial weight;

modeling an equivalent single antenna channel.

9. The computer program product of claim 8, further comprising code for performing the functions of any of claims 2 or 3 or 4 or 5.

10. An apparatus of wireless communication in a wireless communication network, comprising:

at least one processor; and

a memory coupled to the least one processor, wherein the at least one processor is configured to:

determine a cross antenna spatial weight based on combining a scalar weight of the a first antenna and a scalar weight of a second antenna;

calculate an equivalent single antenna CIR and an equivalent single antenna noise variance for the first antenna and the second antenna based the cross antenna spatial weight;

model an equivalent single antenna channel.

11. The apparatus of claim 10, further configured to perform the functions of any of claims 2 or 3 or 4 or 5.