WO2009098532A1

WO2009098532A1 - Apparatus, methods, and computer program products providing improved spatial multiplexing for mimo communication

Info

Publication number: WO2009098532A1
Application number: PCT/IB2008/000272
Authority: WO
Inventors: Klaus Hugl; Jaakko Eero Samuli Visuri
Original assignee: Nokia Corporation; Nokia, Inc.
Priority date: 2008-02-07
Filing date: 2008-02-07
Publication date: 2009-08-13

Abstract

The exemplary embodiments of the invention provide spatial multiplexing for MIMO communication. In particular, some exemplary embodiments of the invention utilize paired antenna schemes that are similar to the rank 1 open loop transmit diversity mode already approved for inclusion in E-UTRAN. In one non-limiting, exemplary embodiment, a method includes: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas (701); and transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel (702).

Description

APPARATUS AND METHOD PROVIDING SPATIAL MULTIPLEXING FOR MIMO COMMUNICATION

TECHNICAL FIELD:

The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, apparatus, methods and computer program products and, more specifically, relate to multiple input/multiple output communication.

10

BACKGROUND:

The following abbreviations are utilized herein:

15 3GPP third generation partnership project

16QAM 16-state quadrature amplitude modulation

BPSK binary phase-shift keying

CQI channel quality indicator

DL downlink (Node B to UE) 0 E-UTRAN evolved universal terrestrial radio access network

FEC forward error correction

HARQ hybrid automatic repeat-request

LTE long term evolution of UTRAN (E-UTRAN)

MIMO multiple input/multiple output 5 Node B base station

OFDM orthogonal frequency division multiplexing

PMI precoding matrix index

QPSK quadrature phase-shift keying

SM spatial multiplexing 0 STBC space-time block codes

SU-MIMO single user MIMO

TX transmission/transmit

UE user equipment, such as a mobile station or mobile terminal UL uplink (UE to Node B)

UTRAN universal terrestrial radio access network

The long term evolution (LTE) of UTRAN is currently a work item within 3GPP. For LTE, one of the targets is to achieve high peak data rates combined with high spectral efficiency. To achieve this, a number of features are being considered, such as HARQ, to maintain a high spectral efficiency. Similarly, MIMO transmission is being considered not only for reaching high peak data rates, but also for improving the average system throughput.

Spatial multiplexing is a transmission technique in MIMO communication whereby independent and separately encoded data signals, so called "streams", are transmitted from each of the multiple transmit antennas. That is, different streams (signals) are transmitted from different antennas. In such a manner, the space dimension is reused (i.e., multiplexed). If the transmitter has N_t antennas and the receiver has N₁- antennas, the maximum spatial multiplexing order (N_s, the number of streams) is: N_s = min(N_t , N₁. ), if a linear receiver is used. This means that N_s streams can be transmitted in parallel, leading to a N_s increase in spectral efficiency over a single-stream (e.g., non-MIMO) system.

One of the MIMO operation modes is DL SU-MIMO, which is based on pre-coded multi- stream transmission to a single user which boosts the user data rates. The precoding is based on codebooks known by the UE and the Node B, as specified in 3GPP TS 36.211 (V8.0.0). Reference may be made to 3GPP TS 36.211 V8.0.0 (2007-09), "3rd Generation Partnership project; Technical Specification Group Radio Access Network; Evolved Universal terrestrial Radio Access (E-UTRA); Physical channels and modulation (Release 8)," 27 September 2007. More specifically, reference with regard to layer mapping for spatial multiplexing may be made to section 6.3.3.2 and reference with regard to layer mapping for transmit diversity may be made to section 6.3.3.3 of 3 GPP TS 36.211 V8.0.0. Reference with regard to precoding may be made to section 6.3.4 of 3GPP TS 36.211 V8.0.0 and, more specifically, to section 6.3.4.2 with regard to precoding for spatial multiplexing and to section 6.3.4.3 with regard to precoding for transmit diversity. In addition to the SU-MIMO mode, various proposals have been made to have a rank adapted open loop mode for high speed scenarios. For example, one such proposal is Rl - 074800, 3GPP TSG RAN WGl Meeting #51, Samsung et al., "Multiple Antenna Transmission for High Mobility UE," Jeju, Korea, 5-9 November 2007. The Rl -074800 proposal discusses a high-speed open-loop SM transmission scheme and rank adaptation for use in optimizing the proposed scheme. The scheme has the Node B cyclically assign different codewords in the codebookto different subcarriers in the scheduled sub-band in the case where the PMI is not reliable or not available.

Other MIMO schemes have also been described. Reference in this regard may be made to U.S. Patent Application Publication No. 2007/0183527 Al, Jia et al., "Space-Time Transmit Diversity Systems and Methods for OFDM Applications," published 09 August 2007. Jia et al. describe OFDM-space-time block code mappings for code rate 1 , 2 and 4 codes for four transmit antennas. A class of STBC codes is described for OFDM applications. Codes for STBC mappings in time, frequency and combined time- frequency directions for multiple antennas are considered. In particular, Jia et al. utilize Alamouti codes

In addition, reference may also be made to Zhuang et al., "Transmit Diversity and Spatial Multiplexing in Four-Transmit- Antenna OFDM," IEEE, 2003. Zhuang et al. also utilize Alamouti codes. More specifically, Zhuang et al. analyze the performance of a design for achieving spatial diversity and spatial multiplexing in an OFDM system with four transmit antennas. The design is essentially a combination of MIMO and the Alamouti scheme in that it multiplexes two Alamouti-encoded symbol streams onto the four transmit antennas. Zhuang et al. describe a linear receiver algorithm for the hybrid STBC/MIMO strategy that does not explicitly require matrix inversion.

SUMMARY: hi one exemplary embodiment of the invention, a method comprising: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and transmitting a multiple input/multiple output (MIMO) cominunication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

In another exemplary embodiment of the invention, a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, said operations comprising: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

In a further exemplary embodiment of the invention, an apparatus comprising: a processor configured to map data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna of a plurality of antennas, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and at least one transmitter configured to transmit a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

In a further exemplary embodiment of the invention, an apparatus comprising: means for mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna of a plurality of antennas, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and means for transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel. BRIEF DESCRIPTION OF THE DRAWINGS:

The foregoing and other aspects of exemplary embodiments of this invention are made more evident in the following Detailed Description, when read in conjunction with the attached Drawing Figures, wherein:

FIG. 1 illustrates a simplified block diagram of exemplary electronic devices that are suitable for use in practicing the exemplary embodiments of this invention;

FIG. 2 shows further details of the exemplary access node depicted in FIG. 1;

FIG. 3 shows further details concerning the operation of the exemplary controller of the exemplary access node depicted in FIG. 2;

FIG. 4 shows further details of the exemplary user equipment depicted in FIG. 1;

FIG. 5 depicts an exemplary system, having four transmission/transmit branches, that is suitable for use in practicing the exemplary embodiments of this invention;

FIG. 6 illustrates a simplified block diagram of an exemplary controller utilized by the access node shown in FIG. 5;

FIG. 7 depicts a flowchart illustrating one non-limiting example of a method for practicing the exemplary embodiments of this invention; and

FIG. 8 depicts a flowchart illustrating another non-limiting example of a method for practicing the exemplary embodiments of this invention.

DETAILED DESCRIPTION: The exemplary embodiments of the invention provide improved spatial multiplexing for MIMO communication, hi particular, some exemplary embodiments of the invention utilize paired antenna schemes that are similar to the rank 1 open loop transmit diversity mode already approved for inclusion in E-UTRAN. As such, some exemplary embodiments of the invention may be easily implemented in conjunction with other approved aspects of E-UTRAN systems, such as various aspects currently specified in 3GPP TS 36.211 V8.0.0, as a non-limiting example. For example, utilization of exemplary paired antenna schemes (see below) may reduce complexity while maintaining high throughput.

Rank 2 transmission for high speed communication using two transmit antennas may be defined as using normal spatial multiplexing, also referred to as vector modulation.

hi another exemplary embodiment of the invention, for high speed communication using four transmit antennas, a spatial multiplexing mode with rank 2 is created by hopping between antenna pairs. For example, a subcarrier 2i transmits two streams from antenna ports 0 and 2, and a subcarrier 2i+l transmits two streams from antenna ports 1 and 3. One benefit of this exemplary scheme for generating two-stream transmission, as compared to the scheme described by Rl -074800, is that it is similar to the rank 1 open loop transmit diversity mode already existing in LTE (see, e.g., 3GPP TS 36.211 V8.0.0).

By way of further explanation, consider the following exemplary embodiment. Let

-1) denote the complex- valued modulation symbols for acode word q where M^₀ is the number of modulation symbols per code word. Moreover, let x^(p) (j) denote the complex symbol x on subchannel j for antenna port p which is then mapped to resource blocks assigned for transmission to a UE. In conjunction with an exemplary embodiment of the invention, this example can be defined as:

Table 1 While this example illustrates the use of a dual codeword approach, the exemplary embodiments of the invention are not limited solely thereto, and may be utilized in conjunction with any suitable number of codewords, including a single codeword spatial multiplexing approach, as a non-limiting example. In accordance with 3GPP TS 36.211 V8.0.0, in some exemplary embodiments, the number of codewords may be limited so as to be less than or equal to a number of layers.

As noted above, the exemplary embodiments of the invention may implement a similar structure as the open loop transmit diversity mode already agreed to for LTE. Therefore, the CQI for the proposed exemplary spatial multiplexing modes in conjunction with the exemplary embodiments of the invention can be based on the transmit diversity CQI, if so needed or desired. In addition, the exemplary embodiments of the invention are generally less complex than some alternative schemes that have been proposed (see, e.g., Rl- 074800) since they do not require any linear combinations at the transmitter or at the receiver (e.g., when creating the effective channel). Moreover, due to the even use of antennas, and since no precoding is needed, the created interference in the frequency domain is not changing. This helps the link adaptation in neighboring cells since, for example, there is no frequency-dependent "flash-light" effect.

Reference is made to FIG. 1 for illustrating a simplified block diagram of various electronic devices that are suitable for use in practicing the exemplary embodiments of this invention. In FIG. 1, an access node (AN) 102 is adapted for wireless communication (e.g., wireless MBVIO communication) with one or more user equipments (UE) 202, all of which are elements (e.g., nodes) of a wireless network 250. The AN 102 may be coupled via a data path 252 to one or more external networks or systems, such as the internet 254, for example. The AN 102 includes a plurality of antennas (ANTl 126, ANTM 146), as does the UE 202 (ANTl 226, ANTiV 246). These antennas, in conjunction with additional components as described below with respect to FIGS. 2 and 4, enable wireless MIMO communication between the AN 102 and the UE 202.

FIG. 2 shows further details of the exemplary AN 102 depicted in FIG. 1. The AN 102 includes a data processor (DP) 104 and a memory (MEM) 106 coupled to the DP 104. The MEM 106 stores a program (PROG) 108. The AN 102 also includes a controller (CONTR) 110 coupled to the DP 104. The CONTR 110 receives data from the DP 104 and outputs a plurality (M) of transmission streams. For convenience, the Mtransmission streams will be referred to herein as transmission (TX) branches, and are shown in FIG.2 as TX branch 1 (TXl) 120 and TX branchM(TXM) 140. The operation and functions of the CONTR 110 will be described in further detail below with respect to FIG. 3. For the purposes of the AN 102 illustrated in FIGS. 1 and 2, it is noted that the value of Mmay comprise any integer greater than or equal to 2, and may be dependent on one or more aspects or attributes of the wireless network and/or access node in question, such as a desired minimum throughput or a number of antennas, as non-limiting examples. In one exemplary embodiment, M= 4 (see FIGS. 5 and 6 below).

Each TX branch (TXl 120 and TXM 140) may be coupled to its own set of components which includes a transmitter and at least one antenna. That is, TXl 120 is coupled to an amplifier (AMP 1) 122 which is in turn coupled to a transceiver (TRANS 1 ) 124 having a transmitter (TX) and a receiver (RX). TXM 140 is coupled to an amplifier (AMPM) 142 which is in turn coupled to a transceiver (TRANSM) 144 having a transmitter (TX) and a receiver (RX). Each TRANS 124, 144 is coupled to at least one antenna (ANTl 126, ANTM 146, respectively) to facilitate communication. The TRANS 124, 144 are for wireless communication (e.g., bidirectional wireless communication, MIMO communication) with a user equipment (e.g., UE 202).

It is noted that each set of components may comprise additional components or processing blocks/functions as required for communication with the user equipment(s). The AMPs 122, 142 are included as a non-limiting example of a suitable component. Although shown as separate blocks in FIG. 1, in further exemplary embodiments the functions of one or more blocks may be performed by other blocks (i.e., combined). As a non-limiting example, in other exemplary embodiments, the DP 104 may perform the functions associated with the CONTR 110. As a further non-limiting example, the TRANS 124, 144 may be located within a single element or block. It is also noted that in various further exemplary embodiments, one or more of the blocks shown in FIG.2 may comprise circuits or specialized circuits, such as integrated circuits (ICs) or application specific integrated circuits (ASICs), as non-limiting examples. Although shown in FIG.2 with one transceiver (TRANS) for each antenna (ANT), in other exemplary embodiments, one or more transceivers may feed a plurality of antennas (e.g., each transceiver feeds two antennas). As a non-limiting example, the AN 102 may comprise a base station, such as a node B or an evolved node B or E-UTRAN node B (eNB).

FIG. 3 shows further details concerning the operation of the exemplary controller (CONTR) 110 of FIG. 2. Generally, the CONTR 110 processes data (e.g., encodes and/or modulates the data symbols) and maps the processed data to a plurality of transmission branches, enabling spatial multiplexing (e.g., hopping between the plurality of transmission branches) to be utilized for the corresponding transmissions (e.g., for a MIMO transmission).

As a more specific example, and with reference to FIG. 3 , the CONTR 110 receives data 150 from the DP 104 as an input. The data 150 is segmented by a segmentation component (SEG) 160 to form the constituent data of a plurality of streams (C streams) . The first stream is encoded by a first encoder (ENC-I) 162 and modulated by a first modulator (MOD-I) 166, with the result being passed to a symbol mapper (MAP) 170. The C^th stream is encoded by the C^ft encoder (ENC-C 164) and modulated by the C^th modulator (MOD-C 168), with the result being passed to the MAP 170. As a non- limiting example, the coding may comprise a FEC code. Also as non-limiting examples, the modulation(s) employed may comprise one or more of BPSK, QPSK and 16QAM. The MAP 170 maps the modulation symbols to the different transmission branches (TXl 120, TXM 140), ensuring that spatial multiplexing is used (i.e., ensuring that the transmissions are spatially multiplexed among the plurality of transmission branches).

Note that the number of streams (C) into which the data 150 is segmented may or may not correspond to the number of transmission branches (M). As a non-limiting example, the data may be segmented into two streams that are separately encoding and modulated (i.e., using two different codewords and two different modulations), while the two streams of modulated symbols are transmitted from four antennas, each stream being transmitted from two antennas (see FIGS. 5 and 6 as further described below).

While FIG. 3 shows each stream being separately encoded and modulated, it should be appreciated that this is not required for the exemplary embodiments of the invention. As a non-limiting example, a single component may handle all of the encoding and/or modulation. Furthermore, while FIG. 3 shows each stream being encoded with a different code (e.g., codeword or codebook) and modulated with a different modulation, it should be appreciated that this is not required for the exemplary embodiments of the invention. For example, single codeword spatial multiplexing may be utilized, wherein a single codeword and single modulation are used to generate a plurality of resulting streams that are transmitted on a plurality of subchannels via a plurality of transmission branches.

FIG. 4 shows further details of the exemplary user equipment depicted in FIG. 1. The UE 202 includes a data processor (DP) 204 and a memory (MEM) 206 coupled to the DP 204. The MEM 206 stores a program (PROG) 208. The UE 202 also includes a reception control unit (RXC) 210 coupled to the DP 204 and a plurality (TV) of antennas (ANTl 226, ANTTV 246) coupled to a plurality of transceivers (TRANSl 224, TRANSTV 244), each transceiver having a transmitter (TX) and a receiver (RX). The TRANS 1 224 and TRANSTV 244 may be coupled to one or more processing blocks (PB 1 222, PBTV 242) which are themselves coupled to the RXC 210.

The UE 202 is configured to receive a MIMO communication via the plurality of antennas (ANTl 226, ANTTV 246) and the plurality of transceivers (TRANSl 224,

TRANSTV 244). The processing blocks (PBl 222, PBTV242) process the received signals.

The RXC 210 receives the processed signals as inputs and is configured to perform operations such as MIMO multi-stream decoding and detection. That is, the RXC 210 is aware of the mapping utilized by the AN 102 (more specifically, the CONTR 110) to produce the transmitted signals and, based on knowledge of the mapping, can properly process the signals to obtain the data.

It is noted that in other exemplary embodiments the UE 202 may comprise additional components or processing blocks/functions as required for communication with the AN 102 or for other purposes or functions. The PBs 222, 242 are included as a non-limiting example of such suitable components. Although shown as separate blocks in FIG. 1, in further exemplary embodiments the functions of one or more blocks may be performed by other blocks (i.e., combined). As a non-limiting example, in other exemplary embodiments, the DP 204 or one or more other processors, chips or components, may perform the functions associated with the RXC 210. As a further non-limiting example, the TRANS 224, 244 may be located within a single element or block. It is also noted that in various further exemplary embodiments, one or more of the blocks shown in FIG. 4 may comprise circuits or specialized circuits, such as integrated circuits (ICs) or application specific integrated circuits (ASICs), as non-limiting examples. Although shown in FIG. 2 with one transceiver (TRANS) for each antenna (ANT), in other exemplary embodiments, one or more transceivers may feed/receive a plurality of antennas.

In general, the various exemplary embodiments of the UE 202 can include, but are not limited to, mobile terminals, mobile phones, cellular phones, personal digital assistants (PDAs) having wireless communication capabilities, portable computers having wireless communication capabilities, image capture devices such as digital cameras having wireless communication capabilities, gaming devices having wireless communication capabilities, music storage and playback appliances having wireless communication capabilities, Internet appliances permitting wireless Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.

The embodiments of this invention may be implemented by computer software executable by one or more of the DPs 104, 204 of the UE 202 and the AN 102, or by hardware, or by a combination of software and hardware.

At least one of the PROGs 108, 208 is assumed to include program instructions that, when executed by the associated DP, enable the electronic device to operate in accordance with the exemplary embodiments of this invention, as discussed herein.

The MEMs 106, 206 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory, as non-limiting examples. The DPs 104, 204 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPs) and processors based on a multi-core processor architecture, as non-limiting examples.

FIG. 5 depicts an exemplary system 300, having four transmission/transmit branches, that is suitable for use in practicing the exemplary embodiments of this invention. The exemplary system 300 includes an access node (AN) 302 in communication with a user equipment (UE) 304. The AN 302 is coupled via a datapath 330 to the internet 332. The AN 302 has four antennas, namely: ANTl 311, ANT2 312, ANT3 313 and ANT4 314. The AN 302 utilizes the four antennas to transmit to the UE 304 in accordance with the exemplary embodiments of the invention. It is noted that the AN 302 includes a number of components, similar to the exemplary AN 102 and components shown in FIGS. 1-3. Note that the transmissions sent via ANTl 311 and ANT3 313 are sent via a first subchannel (CHl), while the transmissions sent via ANT2 312 and ANT4 314 are sent via a second subchannel (CH2).

The UE 304 of FIG. 5 has two antennas, ANTl 321 and ANT2 322, which it uses to receive the transmission from the AN 302. It is noted that the UE 304 includes a number of components, similar to the exemplary UE 202 and components shown in FIGS. 1 and 4. The UE 304 is configured to receive the MIMO transmission sent by the AN 302 and properly perform MIMO multi-stream decoding and detection in order to obtain the data.

FIG. 6 illustrates a simplified block diagram of an exemplary controller (CONTR) 340 utilized by the AN 302 shown in FIG. 5. The CONTR 340 receives data 350 from a data processor of the AN 302 as an input. The data 350 is segmented by a segmentation component (SEG) 360 to form the constituent data of two streams. The first stream is encoded by a first encoder (ENC-I) 362 and modulated by a first modulator (MOD-I) 366, with the result being passed to a symbol mapper (MAP) 370. The second stream is encoded by a second encoder (ENC-2) 364 and modulated by a second modulator (MOD- 2) 168, with the result being passed to the MAP 170. Different codewords are used by ENC-I 362 and ENC-2 364, while different modulations are used by MOD-I 366 and MOD-2 368. The MAP 170 maps the modulation symbols to the four different transmission branches: TXl 371, TX2 372, TX3 373 and TX4 374. Each transmission branch is coupled to a different antenna: ANTl 311, ANT 312, ANT3 313 and ANT4 314, respectively. Note that the transmissions sent via TXl 371 and TX 3 373 are sent via the first subchannel (CHl)₃ while the transmissions sent via TX 2 372 and TX 4 374 are sent via the second subchannel (CH2). In such a manner, the AN 302 utilizes hopping between antenna pairs to provide improved spatial multiplexing for the transmission. The example illustrated in FIGS. 5 and 6 may be consider an exemplary implementation of the invention for open-loop rank 2 MIMO transmission utilizing four transmit antennas in the frequency domain.

As a further non-limiting example utilizing the exemplary system 300 illustrated in FIGS. 5 and 6, a MIMO transmission sent from the AN 302 to the UE 304 may be transmitted in accordance with Table 2 immediately below:

Table 2

As a further non-limiting example utilizing the exemplary system 300 illustrated in FIGS . 5 and 6, a MIMO transmission sent from the AN 302 to the UE 304 may be transmitted in accordance with Table 3 immediately below:

Table 3

As a further non-limiting example utilizing an exemplary system similar to the exemplary system 300 illustrated in FIGS. 5 and 6, consider a case where only three transmission branches, TXl, TX2 and TX3, are present. A MIMO transmission sent from an access node to a user equipment may be transmitted in accordance with Table 4 immediately below:

Table 4

Note that in the above examples (Tables 2-4), the transmissions may interfere with one another, however the UE is still able to decode the information, for example, based on the UE's knowledge of the mapping employed.

Below are provided further descriptions of non-limiting, exemplary embodiments. The below-described exemplary embodiments are separately numbered for clarity and identification. This numbering should not be construed as wholly separating the below descriptions since various aspects of one or more exemplary embodiments may be practiced in conjunction with one or more other aspects or exemplary embodiments.

(1 ) In one exemplary embodiment, and as illustrated in FIG. 7, a method comprising: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas (701 ); and transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel (702).

A method as above, wherein transmitting the MIMO communication does not utilize linear combinations when creating transport channels. A method as in any above, wherein transmitting the MIMO communication does not utilize precoding prior to transmission. A method as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. A method as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing. A method as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

A method as in any above, wherein transmission symbols of the MIMO communication are mapped to each transmission branch according to a mapping comprising:

wherein x^(p) (y) denotes a complex transmission symbol on subchannel j for transmission branchy, wherein d ^(<7) (/V) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

A method as in any above, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches. A method as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system. A method as in any above, wherein the method is implemented within an evolved universal terrestrial radio access network. A computer program product embodied on a computer-readable medium, comprising program instructions the execution of which result in operations according to any of the above methods.

A method as in any above, further comprising: separating the data into portions, wherein each portion is separately encoded and/or modulated prior to mapping.

(2) In another exemplary embodiment, a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, said operations comprising: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas (701); and transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel (702).

A program storage device as above, wherein transmitting the MIMO communication does not utilize linear combinations when creating transport channels. A program storage device as in any above, wherein transmitting the MIMO communication does not utilize precoding prior to transmission. A program storage device as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. A program storage device as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing. A program storage device as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

A program storage device as in any above, wherein transmission symbols of the MIMO communication are mapped to each transmission branch according to a mapping comprising:

wherein x^(p) (y) denotes a complex transmission symbol on subchannel j for transmission branchy, wherein d^ (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

A program storage device as in any above, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches. A program storage device as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system. A program storage device as in any above, wherein the machine comprises a node within an evolved universal terrestrial radio access network.

(3) In another exemplary embodiment, an apparatus (102) comprising: a processor (110) configured to map data to a plurality of transmission branches (120, 140), wherein each transmission branch corresponds to at least one antenna of a plurality of antennas (126, 146), wherein the plurality of transmission branches (120, 140) are divided into a plurality of sets with at least one set having at least two antennas; and at least one transmitter (124, 144) configured to transmit a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches (120, 140) with each set on a different subchannel.

An apparatus as above, wherein when transmitting the MIMO communication, the at least one transmitter does not utilize linear combinations when creating transport channels. An apparatus as in any above, wherein when transmitting the MIMO communication, the at least one transmitter does not utilize precoding prior to transmission. An apparatus as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. An apparatus as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing. An apparatus as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

An apparatus as in any above, wherein the processor maps transmission symbols of the MIMO communication to each transmission branch according to a mapping comprising:

wherein X^¹ U) denotes a complex transmission symbol on subchannel j for transmission branch/?, wherein d ^(<7) (Jz) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

An apparatus as in any above, wherein the at least one transmitter is configured to transmit the MIMO communication by hopping between the sets of transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system. An apparatus as in any above, wherein the apparatus comprises a node of an evolved universal terrestrial radio access network. An apparatus as in any above, wherein the apparatus comprises a base station. An apparatus as in any above, further comprising the plurality of antennas.

(4) In another exemplary embodiment, an apparatus (102) comprising: means for mapping (110) data to a plurality of transmission branches (120, 140), wherein each transmission branch corresponds to at least one antenna of a plurality of antennas (126, 146), wherein the plurality of transmission branches (120, 140) are divided into a plurality of sets with at least one set having at least two antennas; and means for transmitting (124, 144) a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches (120, 140) with each set on a different subchannel.

An apparatus as above, wherein when transmitting the MDVIO communication, the means for transmitting does not utilize linear combinations when creating transport channels. An apparatus as in any above, wherein when transmitting the MIMO communication, the means for transmitting does not utilize precoding prior to transmission. An apparatus as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. An apparatus as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing. An apparatus as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches. An apparatus as in any above, wherein the means for mapping maps transmission symbols of the MIMO communication to each transmission branch according to a mapping comprising:

wherein x^(p) (j) denotes a complex transmission symbol on subchannel j for transmission branchy, wherein d^{q) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

An apparatus as in any above, wherein the means for transmitting is further for transmitting the MIMO communication by hopping between the sets of transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system. An apparatus as in any above, wherein the apparatus comprises a node of an evolved universal terrestrial radio access network. An apparatus as in any above, wherein the apparatus comprises a base station. An apparatus as in any above, wherein the means for mapping comprises at least one processor and the means for transmitting comprises at least one transceiver. An apparatus as in any above, further comprising the plurality of antennas.

(5) In another exemplary embodiment, an apparatus comprising: mapping circuitry configured to map data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna of a plurality of antennas, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and transmission circuitry configured to transmit a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

An apparatus as above, wherein when transmitting the MIMO communication, the transmission circuitry does not utilize linear combinations when creating transport channels. An apparatus as in any above, wherein when transmitting the MIMO communication, the transmission circuitry does not utilize precoding prior to transmission. An apparatus as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. An apparatus as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing. An apparatus as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

An apparatus as in any above, wherein the mapping circuitry is configured to map transmission symbols of the MIMO communication to each transmission branch according to a mapping comprising:

wherein

denotes a complex transmission symbol on subchannel j for transmission branch^, wherein d ^(<?) (K) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

An apparatus as in any above, wherein the transmission circuitry is configured to transmit the MIMO communication by hopping between the sets of transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system. An apparatus as in any above, wherein the apparatus comprises a node of an evolved universal terrestrial radio access network. An apparatus as in any above, wherein the apparatus comprises a base station. An apparatus as in any above, further comprising the plurality of antennas.

An apparatus as in any above, wherein the apparatus is embodied on or within one or more: processors, data processors, integrated circuits, application-specific integrated circuits, processing blocks, modules, memories, data storage devices, removable storage devices, chipsets, chips, processing components or any suitable combination thereof.

(6) In another exemplary embodiment, an apparatus comprising: input circuitry configured to receive data; and mapping circuitry configured to map the data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna of a plurality of antennas, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas.

An apparatus as above, wherein the mapping of the data to the plurality of transmission branches is configured to be utilized in conjunction with transmission of a corresponding multiple input/multiple output (MIMO) communication that is transmitted as spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

An apparatus as in any above, further comprising: transmission circuitry configured to transmit a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

wherein x^{p) (j) denotes a complex transmission symbol on subchannel j for transmission branchy, wherein d ⁽³⁾ (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

An apparatus as in any above, wherein the transmission circuitry is configured to transmit the MIMO communication by hopping between the sets of transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcanϊers in an orthogonal frequency division multiplexing system. An apparatus as in any above, wherein the apparatus comprises a node of an evolved universal terrestrial radio access network. An apparatus as in any above, wherein the apparatus comprises a base station. An apparatus as in any above, further comprising the plurality of antennas.

(7) In another exemplary embodiment, and as illustrated in FIG. 8, a method comprising: receiving a multiple input/multiple output (MIMO) communication (801); decoding the MIMO communication utilizing knowledge of a mapping employed to produce the MIMO communication, wherein the mapping comprises a mapping of data to transmission branches that are used to transmit the MIMO communication as spatially multiplexed streams (802).

A method as above, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas, wherein each set utilizes a different subchannel. A method as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches. A method as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

A method as in any above, wherein transport channels for the MIMO communication are not created utilizing linear combinations. A method as in any above, wherein precoding is not used prior to transmission of the MIMO communication. A method as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. A method as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

A method as in any above, wherein the mapping comprises:

wherein x^(p) (/) denotes a complex transmission symbol on subchannel j for transmission branchy, wherein d ^(?) (Jc) denotes at least one complex- valued modulation symbol on subchannel k for a code word q. A method as in any above, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches. A method as in any above, wherein the method is implemented within an evolved universal terrestrial radio access network. A computer program product embodied on a computer-readable medium, comprising program instructions the execution of which result in operations according to any of the above methods.

(8) In another exemplary embodiment, a program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, said operations comprising: receiving a multiple input/multiple output (MIMO) communication (801); decoding the MIMO communication utilizing knowledge of a mapping employed to produce the MIMO communication, wherein the mapping comprises a mapping of data to transmission branches that are used to transmit the MIMO communication as spatially multiplexed streams (802).

A program storage device as above, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas, wherein each set utilizes a different subchannel. A program storage device as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches. A program storage device as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

A program storage device as in any above, wherein transport channels for the MIMO communication are not created utilizing linear combinations. A program storage device as in any above, wherein precoding is not used prior to transmission of the MIMO communication. A program storage device as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. A program storage device as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

A program storage device as in any above, wherein the mapping comprises:

wherein x^{p) {j) denotes a complex transmission symbol on subchannel j for transmission branch/?, wherein d^{q) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

A program storage device as in any above, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches. A program storage device as in any above, wherein the machine comprises a node in an evolved universal terrestrial radio access network.

(9) In another exemplary embodiment, an apparatus (202) comprising: a plurality of receivers (224, 244) configured to receive a multiple input/multiple output (MIMO) communication; and a processor (210) configured to decode the MIMO communication utilizing knowledge of a mapping employed to produce the MIMO communication, wherein the mapping comprises a mapping of data to transmission branches that are used to transmit the MIMO communication as spatially multiplexed streams.

An apparatus as above, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into aplurality of sets with at least one set having at least two antennas, wherein each set utilizes a different subchannel. An apparatus as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

An apparatus as in any above, wherein transport channels for the MIMO communication are not created utilizing linear combinations. An apparatus as in any above, wherein precoding is not used prior to transmission of the MIMO communication. An apparatus as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. An apparatus as in any above, wherein the MDVIO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

An apparatus as in any above, wherein the mapping comprises:

wherein x^(p) (y) denotes a complex transmission symbol on subchannel j for transmission branch p, wherein d ^(?) (Jc) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

An apparatus as in any above, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches. An apparatus as in any above, wherein the apparatus comprises a node in an evolved universal terrestrial radio access network. An apparatus as in any above, wherein the apparatus comprises a user equipment, mobile node, mobile terminal, mobile phone or cellular phone.

(10) In another exemplary embodiment, an apparatus (202) comprising: a plurality of means for receiving (224, 244) a multiple input/multiple output (MEMO) communication; and means for decoding (210) the MIMO communication utilizing knowledge of a mapping employed to produce the MIMO communication, wherein the mapping comprises a mapping of data to transmission branches that are used to transmit the MIMO communication as spatially multiplexed streams.

An apparatus as in any above, wherein transport channels for the MIMO communication are not created utilizing linear combinations. An apparatus as in any above, wherein precoding is not used prior to transmission of the MIMO communication. An apparatus as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. An apparatus as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

An apparatus as in any above, wherein the mapping comprises:

wherein x^(p) (y) denotes a complex transmission symbol on subchannel j for transmission branch/?, wherein d ^(<7) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

An apparatus as in any above, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches. An apparatus as in any above, wherein the apparatus comprises a node in an evolved universal terrestrial radio access network. An apparatus as in any above, wherein the apparatus comprises a user equipment, mobile node, mobile terminal, mobile phone or cellular phone. (11) In another exemplary embodiment, an apparatus comprising: reception circuitry configured to receive a multiple input/multiple output (MIMO) communication; and decoding circuitry configured to decode the MIMO communication utilizing knowledge of a mapping employed to produce the MIMO communication, wherein the mapping comprises a mapping of data to transmission branches that are used to transmit the MIMO communication as spatially multiplexed streams.

An apparatus as above, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas, wherein each set utilizes a different subchannel. An apparatus as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

An apparatus as in any above, wherein the mapping comprises:

wherein x^{p) {j) denotes a complex transmission symbol on subchannel j for transmission branchy, wherein d^iq) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

(12) An apparatus comprising: input circuitry configured to receive a multiple input/multiple output (MIMO) communication as an input; and decoding circuitry configured to decode the MIMO communication utilizing knowledge of a mapping employed to produce the MIMO communication, wherein the mapping comprises a mapping of data to transmission branches that are used to transmit the MIMO communication as spatially multiplexed streams.

An apparatus as above, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas, wherein each set utilizes a different subchannel. An apparatus as in any above, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches. An apparatus as in any above, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system. An apparatus as in any above, further comprising reception circuitry configured to receive the MIMO communication. An apparatus as in any above, wherein transport channels for the MIMO communication are not created utilizing linear combinations. An apparatus as in any above, wherein precoding is not used prior to transmission of the MIMO communication. An apparatus as in any above, wherein the MIMO communication has a spatial multiplexing rate of 2. An apparatus as in any above, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

An apparatus as in any above, wherein the mapping comprises:

wherein x^{p) (j) denotes a complex transmission symbol on subchannel j for transmission branch p, wherein d^{q) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

(13) A system comprising: an apparatus as described above in one of numbers (3)-(6); and an apparatus as described above in one of numbers (9)-(12). A system as in the previous, and further comprising one or more additional aspects of the exemplary embodiments of the invention as further described herein.

The exemplary embodiments of the invention, as discussed above and as particularly described with respect to exemplary methods, may be implemented as a computer program product comprising program instructions embodied on a tangible computer- readable medium. Execution of the program instructions results in operations comprising steps of utilizing the exemplary embodiments or steps of the method.

It should be understood that MIMO communication generally involves transmission from a plurality of antennas that is substantially simultaneous. It should further be noted that the terms "connected," "coupled," or any variant thereof mean any connection or coupling, direct or indirect, between two or more elements, and may encompass the presence of one or more intermediate elements between two elements that are "connected" or "coupled" together. The coupling or connection between the elements can be physical, logical, or a combination thereof. As employed herein two elements may be considered to be "connected" or "coupled" together by the use of one or more wires, cables and/or printed electrical connections, as well as by the use of electromagnetic energy, such as electromagnetic energy having wavelengths in the radio frequency region, the microwave region and the optical (both visible and invisible) region, as several non-limiting and non-exhaustive examples.

While the exemplary embodiments have been described above in the context of the E- UTRAN (UTRAN-LTE) system, it should be appreciated that the exemplary embodiments of this invention are not limited for use with only this one particular type of wireless communication system, and that they may be used to advantage in other wireless communication systems.

In general, the various exemplary embodiments may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, flow charts, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.

The exemplary embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.

Programs, such as those provided by Synopsys, Inc. of Mountain View, California and Cadence Design, of San Jose, California automatically route conductors and locate components on a semiconductor chip using well established rules of design as well as libraries of pre-stored design modules. Once the design for a semiconductor circuit has been completed, the resultant design, in a standardized electronic format (e.g., Opus, GDSII, or the like) may be transmitted to a semiconductor fabrication facility or "fab" for fabrication.

The foregoing description has provided by way of exemplary and non-limiting examples a full and informative description of the invention. However, various modifications and adaptations may become apparent to those skilled in the relevant arts in view of the foregoing description, when read in conjunction with the accompanying drawings and the appended claims. However, all such and similar modifications of the teachings of this invention will still fall within the scope of the non-limiting and exemplary embodiments of this invention.

Furthermore, some of the features of the preferred embodiments of this invention could be used to advantage without the corresponding use of other features. As such, the foregoing description should be considered as merely illustrative of the principles, teachings and exemplary embodiments of this invention, and not in limitation thereof.

Claims

CLAIMSWhat is claimed is:

1. A method comprising: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

2. A method as in claim 1 , wherein transmitting the MIMO communication does not utilize linear combinations when creating transport channels.

3. A method as in claim 1 or 2, wherein transmitting the MIMO communication does not utilize precoding prior to transmission.

4. A method as in any one of claims 1 -3 , wherein the MIMO communication has a spatial multiplexing rate of 2.

5. A method as in any one of claims 1 -4, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

6. A method as in any one of claims 1 -5, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

7. A method as in claim 6, wherein transmission symbols of the MIMO communication are mapped to each transmission branch according to a mapping comprising:

wherein x^{p) {j) denotes a complex transmission symbol on subchannel j for transmission branch p, wherein d^ (Jz) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

8. A method as in any one of claims 1-7, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches.

9. A method as in any one of claims 1 -8, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

10. A method as in any one of claims 1-8, wherein the method is implemented within an evolved universal terrestrial radio access network.

11. A computer program product embodied on a computer-readable medium, comprising program instructions the execution of which result in operations according to any of the methods of claims 1-10.

12. A program storage device readable by a machine, tangibly embodying a program of instructions executable by the machine for performing operations, said operations comprising: mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

13. A program storage device as in claim 12, wherein transmitting the MIMO communication does not utilize linear combinations when creating transport channels.

14. A program storage device as in claim 12 or 13, wherein transmitting the MIMO communication does not utilize precoding prior to transmission.

15. A program storage device as in any one of claims 12-14, wherein the MIMO communication has a spatial multiplexing rate of 2.

16. A program storage device as in any one of claims 12-15, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

17. A program storage device as in any one of claims 12-16, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

18. A program storage device as in claim 17, wherein transmission symbols of the MIMO communication are mapped to each transmission branch according to a mapping comprising:

wherein x^^p) (j) denotes a complex transmission symbol on subchannel j for transmission branch/*, wherein d ^(?) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word g.

19. A program storage device as in any one of claims 12-18, wherein the MIMO communication is transmitted by hopping between the sets of transmission branches.

20. A program storage device as in any one of claims 12-19, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

21. A program storage device as in any one of claims 12-19, wherein the machine comprises a node within an evolved universal terrestrial radio access network.

22. An apparatus comprising: a processor configured to map data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna of a plurality of antennas, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and at least one transmitter configured to transmit a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

23. An apparatus as in claim 22, wherein when transmitting the MIMO communication, the at least one transmitter does not utilize linear combinations when creating transport channels.

24. An apparatus as in claim 22 or 23, wherein when transmitting the MIMO communication, the at least one transmitter does not utilize precoding prior to transmission.

25. An apparatus as in any one of claims 22-24, wherein the MIMO communication has a spatial multiplexing rate of 2.

26. An apparatus as in any one of claims 22-25, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

27. An apparatus as in any one of claims 22-26, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

28. An apparatus as in claim 27, wherein the processor maps transmission symbols of the MIMO communication to each transmission branch according to a mapping comprising:

wherein x^{p) (j) denotes a complex transmission symbol on subchannel j for transmission branch/?, wherein d^{q) (k) denotes at least one complex- valued modulation symbol on subchannel k for a code word q.

29. An apparatus as in any one of claims 22-28, wherein the at least one transmitter is configured to transmit the MIMO communication by hopping between the sets of transmission branches.

30. An apparatus as in any one of claims 22-29, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

31. An apparatus as in any one of claims 21-29, wherein the apparatus comprises a node of an evolved universal terrestrial radio access network.

32. An apparatus as in any one of claims 22-31 , wherein the apparatus comprises a base station.

33. An apparatus comprising: means for mapping data to a plurality of transmission branches, wherein each transmission branch corresponds to at least one antenna of a plurality of antennas, wherein the plurality of transmission branches are divided into a plurality of sets with at least one set having at least two antennas; and means for transmitting a multiple input/multiple output (MIMO) communication by transmitting spatially multiplexed streams via the plurality of transmission branches with each set on a different subchannel.

34. An apparatus as in claim 33, wherein when transmitting the MIMO communication, the means for transmitting does not utilize linear combinations when creating transport channels.

35. An apparatus as in claim 33 or 34, wherein when transmitting the MIMO communication, the means for transmitting does not utilize precoding prior to transmission.

36. An apparatus as in any one of claims 33-35, wherein the MIMO communication has a spatial multiplexing rate of 2.

37. An apparatus as in any one of claims 33-36, wherein the MIMO communication utilizes single codeword spatial multiplexing or dual codeword spatial multiplexing.

38. An apparatus as in any one of claims 33-37, wherein the plurality of sets consists of two sets, wherein each set consists of two transmission branches.

39. An apparatus as in claim 38, wherein the means for mapping maps transmission symbols of the MIMO communication to each transmission branch according to a mapping comprising:

wherein x^{p) ' (J) denotes a complex transmission symbol on subchannel j for transmission branchp, wherein d ^{q) (k) denotes at least one complex-valued modulation symbol on subchannel k for a code word q.

40. An apparatus as in any one of claims 33-39, wherein the means for transmitting is further for transmitting the MIMO communication by hopping between the sets of transmission branches.

41. An apparatus as in any one of claims 33-40, wherein the different subchannels comprise different subcarriers in an orthogonal frequency division multiplexing system.

42. An apparatus as in any one of claims 33-40, wherein the apparatus comprises a node of an evolved universal terrestrial radio access network.

43. An apparatus as in any one of claims 33-42, wherein the apparatus comprises a base station.

44. An apparatus as in any one of claims 33-43, wherein the means for mapping comprises at least one processor and the means for transmitting comprises at least one transceiver.