Single user multiple input multiple output user equipment

In accordance with the exemplary embodiments of the invention there is at least a method, apparatus, and a computer program to perform operations including receiving information descriptive of a type of radio access which a user equipment is acting on, and in response to receiving the information descriptive of a particular type of radio access, transmitting from a multiple transmit antenna user equipment so that the transmission appears, at a receiver, to have been made by a single antenna user equipment, or by a user equipment that supports antenna switching/selection.

TECHNICAL FIELD

The exemplary and non-limiting embodiments of this invention relate generally to wireless communication systems, methods, devices and computer programs and, more specifically, relate to multiple input/multiple output (MIMO) transmissions from a user equipment having a plurality of transmit antennas.

BACKGROUND

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

3GPP third generation partnership project

EPC evolved packet core

CDM code division multiplexing

CQI channel quality indicator

FDD frequency division duplex

FDMA frequency division multiple access

LTE long term evolution

MAC medium access control

Node B base station

OFDMA orthogonal frequency division multiple access

O&M operations and maintenance

PDCP packet data convergence protocol

PHY physical layer

PUCCH physical uplink control channel

PUSCH physical uplink shared channel

RLC radio link control

RRC radio resource control

SGW serving gateway

SC-FDMA single carrier, frequency division multiple access

SRS sounding reference signal

SU-MIMO single user multiple input multiple output

TDD time division duplex

TTI transmission timing interval

UE user equipment

UTRAN universal terrestrial radio access network

The specification of a communication system known as evolved UTRAN (EUTRAN, also referred to as UTRAN-LTE or as EUTRA) is currently nearing completion within the 3 GPP. As specified the DL access technique is OFDMA, and the UL access technique is SC-FDMA.

One specification of interest is 3GPP TS 36.300, V8.6.0 (2008-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA) and Evolved Universal Terrestrial Access Network (EUTRAN); Overall description; Stage 2 (Release 8), incorporated by reference herein in its entirety.

FIG. 1reproduces Figure 4.1 of 3GPP TS 36.300, and shows the overall architecture of the EUTRAN system. The EUTRAN system includes eNBs, providing the EUTRA user plane (PDCP/RLC/MAC/PHY) and control plane (RRC) protocol terminations towards the UE. The eNBs are interconnected with each other by means of an X2 interface. The eNBs are also connected by means of an S1 interface to an EPC, more specifically to a MME (Mobility Management Entity) by means of a S1 MME interface and to a Serving Gateway (SGW) by means of a S1 interface. The S1 interface supports a many to many relationship between MMEs/Serving Gateways and eNBs.

The eNB hosts the following functions:

functions for Radio Resource Management: Radio Bearer Control, Radio Admission Control, Connection Mobility Control, Dynamic allocation of resources to UEs in both uplink and downlink (scheduling);

IP header compression and encryption of the user data stream;

selection of a MME at UE attachment;

routing of User Plane data towards Serving Gateway;

scheduling and transmission of paging messages (originated from the MME);

scheduling and transmission of broadcast information (originated from the MME or O&M); and

measurement and measurement reporting configurations for providing mobility and scheduling.

The system described above may be referred to for convenience as LTE Rel-8, or simply as Rel-8. In general, the set of specifications given generally as 3GPP TS 36.xyz (e.g., 36.101, 36.211, 36.311, 36.312, etc.) may be seen as describing the entire Rel-8 LTE system.

Of particular interest herein are the further releases of 3GPP LTE targeted towards future IMT-A systems, referred to herein for convenience simply as LTE-Advanced (LTE-A).

Reference can also be made to 3GPP TR 36.913, V8.0.0 (2008-06), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Requirements for Further Advancements for E-UTRA (LTE-Advanced) (Release 8), which is incorporated by reference herein in its entirety.

LTE-A will be a radio system fulfilling the ITU-R requirements for IMT-Advanced while maintaining backwards compatibility with LTE Rel-8. It is assumed at present that single user (SU) MIMO UEs having, for example, two, three or four transmission antennas will be part of LTE-A.

Due to the required backwards compatibility, an LTE-A UE must operate in an LTE Rel-8 cell or network. However, LTE Rel-8 supports mainly single antenna UL transmissions, with an option for transmit antenna selection. Thus, one important item related to the specification and design of a LTE-A SU-MIMO UE is the transmission capability of the UE in a LTE Release 8 cell.

SUMMARY

In an exemplary aspect of the invention, there is a method comprising receiving information descriptive of a type of radio access which a user equipment is acting on, and in response to receiving the information descriptive of a particular type of radio access, transmitting from a multiple transmit antenna user equipment so that the transmission appears, at a receiver, to have been made by a single antenna user equipment, or by a user equipment that supports antenna switching/selection.

In another exemplary aspect of the invention, there is an apparatus comprising at least one processor, and at least one memory including computer program code, where the at least one memory and the computer program code are configured, with the at least one processor, to cause the apparatus to at least receive information descriptive of a type of radio access which a user equipment is acting on, and in response to receiving the information descriptive of a particular type of radio access, transmit from a multiple transmit antenna user equipment so that the transmission appears, at a receiver, to have been made by a single antenna user equipment, or by a user equipment that supports antenna switching/selection.

DETAILED DESCRIPTION

In addition to the two 3GPP specifications noted in the background section, reference may also be made to 3GPP TS 36.101, V8.3.0 (2008-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA); User equipment (UE) radio transmission and reception (Release 8), “Transmitter characteristics”, describes the UE Rel-8 transmitter operation, which is incorporated by reference herein in its entirety.

Reference may also be made to 3GPP TS 36.211, V8.4.0 (2008-09), 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Evolved Universal Terrestrial Radio Access (EUTRA); Physical channels and modulation (Release 8). This document describes various UL channels, including the PUSCH and PUCCH discussed below, as well as the SRS and precoding. PUSCH frequency hopping is described in sub clause 5.3.4, “Mapping to physical resources”.

The exemplary embodiments of this invention provide a multi-antenna transmission arrangement for an LTE-A SU-MIMO UE in a Rel-8 cell. While the ensuing description is focused on the FDD mode, the exemplary embodiments pertain as well to the TDD mode.

For an LTE-A UE with multiple transmission antennas to operate in the LTE Rel-8 cell, an UL transmission from multiple antennas that is transparent to the base station (eNB) is needed. Several considerations need to be taken into account in this type of transmission arrangement:

(i) the transmission arrangement should support existing Rel-8 channels and formats;

(ii) the transmission should appear to the eNB as a single antenna transmission or, alternatively on the PUSCH and SRS, as an eNB directed antenna selection transmission with two transmit antennas; and

(iii) the transmission arrangement should not change considerably the statistical properties of the received signal so that undesirable impacts on eNB estimators and algorithms can be avoided (e.g., the impact on algorithms such as channel estimation, UE velocity estimation and frequency domain scheduling based on SRS feedback should be minimized).

Further considerations may include the desirability that power amplifiers (PAs) in a SU-MIMO UE be dimensioned according to the multi-antenna transmission, thereby resulting in smaller PAs. For example, 21 dBm PAs may be used in a 2-antenna UE, as opposed to a 24 dBm PA in a single antenna UE. Hence, the transmission arrangement may preferably optimize the use of all transmission power resources available at the UE (in order to maintain the UL coverage of the Rel-8 network with the SU-MIMO UE).

Furthermore, the transmission arrangement should mitigate the impact of a possible negative correlation between transmit antennas.

Before describing in further detail the exemplary embodiments of this invention, reference is made toFIG. 2Afor illustrating a simplified block diagram of various electronic devices and apparatus that are suitable for use in practicing the exemplary embodiments of this invention. InFIG. 2Aa wireless network1is adapted for communication over a wireless link11with an apparatus, such as a mobile communication device which may be referred to as a UE10, via a network access node, such as a Node B (base station), and more specifically an eNB12. The network1may include a network control element (NCE)14that may include the MME/SGW functionality shown inFIG. 1, and which provides connectivity with a further network, such as a telephone network and/or a data communications network (e.g., the internet). The UE10includes a controller, such as a computer or a data processor (DP)10A, a computer-readable memory medium embodied as a memory (MEM)10B that stores a program of computer instructions (PROG)10C, and a suitable radio frequency (RF) transceiver10D for bidirectional wireless communications with the eNB12via a plurality of antennas36. For the purposes of describing this invention it may be assumed that the UE10includes at least two transmit antennas36, and a corresponding number of transmitter (Tx) power amplifiers. Note that in a typical configuration there are also at least two receive (Rx) antennas at the eNB12side, and typically also two Rx chains at the UE10side (for LTE).

FIG. 4shows in greater detail a portion of the UE transceiver10A shown inFIG. 2A. In this exemplary embodiment there are four transmit antennas36, each having an associated Tx power amplifier (PA). Also shown are a corresponding number of phase rotators, discussed in further detail below.

The eNB12also includes a controller, such as a computer or a data processor (DP)12A, a computer-readable memory medium embodied as a memory (MEM)12B that stores a program of computer instructions (PROG)12C, and a suitable RF transceiver12D for communication with the UE10via one or more antennas. The eNB12is coupled via a data/control path13to the NCE14. The path13may be implemented as the S1 interface shown inFIG. 1. The eNB12may also be coupled to another eNB via data/control path15, which may be implemented as the X2 interface shown inFIG. 1.

At least one of the PROGs10C and12C is assumed to include program instructions that, when executed by the associated DP, enable the device to operate in accordance with the exemplary embodiments of this invention, as will be discussed below in greater detail.

That is, the exemplary embodiments of this invention may be implemented at least in part by computer software executable by the DP10A of the UE10and/or by the DP12A of the eNB12, or by hardware, or by a combination of software and hardware (and firmware).

For the purposes of describing the exemplary embodiments of this invention the UE10may be assumed to also include a Tx control function (Tx_CNTR)10E. The eNB12may be assumed to include an UL signal processor12E that operates on signals received from the UE10.

FIG. 2Billustrates further detail of an exemplary UE10in both plan view (left) and sectional view (right), and the invention may be embodied in one or some combination of those more function specific components. AtFIG. 2Bthe UE10has a graphical display interface20and a user interface22illustrated as a keypad but understood as also encompassing touch screen technology at the graphical display interface20and voice recognition technology received at the microphone24. A power actuator26controls the device being turned on and off by the user. The exemplary UE10may have a camera28which is shown as being forward facing (e.g., for video calls) but may alternatively or additionally be rearward facing (e.g., for capturing images and video for local storage). The camera28is controlled by a shutter actuator30and optionally by a zoom actuator30which may alternatively function as a volume adjustment for the speaker(s)34when the camera28is not in an active mode.

Within the sectional view ofFIG. 2Bare seen the multiple transmit antennas, and possibly also multiple receive antennas36that are typically used for cellular communication. The antennas36may be multi-band for use with other radios in the UE. The operable ground plane for the antennas36is shown by shading as spanning the entire space enclosed by the UE housing though in some embodiments the ground plane may be limited to a smaller area, such as disposed on a printed wiring board on which the power chip38is formed. The power chip38controls power amplification on the channels being transmitted and/or across the antennas that transmit simultaneously where spatial diversity is used, and amplifies the received signals. The power chip38outputs the amplified received signal to the radio frequency (RF) chip40which demodulates and down converts the signal for baseband processing. The baseband (BB) chip42detects the signal which is then converted to a bit stream and finally decoded. Similar processing occurs in reverse for signals generated in the apparatus10and transmitted from it.

Those signals that go to and from the camera28pass through an image/video processor44that encodes and decodes the image frames. A separate audio processor46may also be present controlling signals to and from the speakers34and the microphone24. The graphical display interface20is refreshed from a frame memory48as controlled by a user interface chip50which may process signals to and from the display interface20and/or additionally process user inputs from the keypad22and elsewhere.

Certain embodiments of the UE10may also include one or more secondary radios such as a wireless local area network radio WLAN37and a Bluetooth® radio39, which may incorporate an antenna on the chip or be coupled to an antenna off the chip. Throughout the apparatus are various memories such as random access memory RAM43, read only memory ROM45, and in some embodiments removable memory such as the illustrated memory card47on which the various programs10C are stored. All of these components within the UE10are normally powered by a portable power supply such as a battery49.

The processors38,40,42,44,46,50, if embodied as separate entities in a UE10or eNB12, may operate in a slave relationship to the main processor10A,12A, which may then be in a master relationship to them. Embodiments of this invention may be disposed across various chips and memories as shown, or disposed within another processor that combines some of the functions described above forFIG. 2B. Any or all of these various processors ofFIG. 2Baccess one or more of the various memories, which may be on chip with the processor or separate from the processor. Similar function-specific components that are directed toward communications over a network broader than a piconet (e.g., components36,38,40,42-45and47) may also be disposed in exemplary embodiments of the access node12, which may have an array of tower mounted antennas rather than the two shown atFIG. 2B.

Note that the various integrated circuits (e.g., chips38,40,42, etc.) that were described above may be combined into a fewer number than described and, in a most compact case, may all be embodied physically within a single chip.

The exemplary embodiments of this invention provide a transmission arrangement for the LTE-A SU-MIMO UE10that optimizes UL performance in LTE Rel-8, and potentially in LTE Release 9 (and beyond) cells/networks as well.

The SU-MIMO UE10, which has the multiple transmit antennas36and power amplifiers, changes the UL multi-antenna transmission based on received information that is descriptive of the cell/network type (e.g., Rel-8/Rel-9/Rel-10).

When the LTE-A SU-MIMO UE10is connected to the Rel-8 eNB12, the UL signal is generated according to the Rel-8 specifications and it is transmitted from one or multiple UE antennas36. The transmission arrangement provides the eNB12with multiple signal combinations from different UE transmit antennas36, while the signal properties that appear to the Rel-8 eNB are maintained to appear appropriate both in the time and the frequency domains. The change of transmit antenna combinations use discontinuous frequency allocation in the case of PUCCH and frequency hopping PUSCH, a Rel-8 option for UE transmit antenna selection and a gradual change in the frequency domain.

The multi-antenna transmissions appear to the Rel-8 eNB12as Rel-8 transmissions from a single antenna UE or, alternatively, from a UE that supports 2-antenna switching. Transmission arrangements involve antenna switching as well as antenna virtualization based on antenna grouping, precoding and/or cyclic delay.

Discussed first is UE10transmission on the PUCCH or on the frequency hopping PUSCH. In these cases the UE10transmits on resource block sets that are separate in frequency. Thus, there can be discontinuity in the frequency domain response appearing to the Rel-8 eNB12. The transmission arrangements in accordance with the exemplary embodiments of this invention utilize this possibility to employ different antenna configurations in different parts of the LTE Rel-8 bandwidth.

The following options are made available for use by the UE10.

Option 1: In this first option the UE10selects and uses one of the transmit antennas36available at the UE. Different ones of the antennas36are used in consecutive slots or sub-frames that are transmitted at different frequencies (that is, within the frequency hopping period). For example, slot0is transmitted from antenna1and slot1is transmitted from antenna2on the PUCCH. One exemplary advantage of this approach is simplicity, while fulfilling most of the considerations discussed above.

Option 2: In this second option the UE10virtualizes multiple transmit antennas by grouping them into antenna groups, and transmits the same signal from all antennas in an antenna group. Different antenna groups are used in consecutive slots or sub-frames that are transmitted at different frequencies (that is, within the frequency hopping pattern). As a non-limiting example, for a PUCCH transmission antenna group1can contain antennas1and3and antenna group2can contain antennas2and4. Then slot0may be transmitted from antenna group1and slot1may be transmitted from antenna group2. Changing the antenna grouping as described serves to mitigate the impact of a possible negative correlation of the radio channel between the antenna groups. One exemplary advantage of this approach is simplicity, while fulfilling the considerations discussed above. Note that this second option reduces to the first option in the case of two UE10transmit antennas36.

Option 3: In this third option the UE10virtualizes multiple transmit antennas by the use of precoding vectors, and switches between the precoding vectors. It should be noted that it may be preferred to use precoding vectors having a constant modulus, although the use of precoding vectors with constant modulus is not a requirement to implement the exemplary embodiments of this invention. In general, a first precoding vector may be associated with a first set of precoding weights, and a second precoding vector may be associated with a second set of precoding weights. In order to mitigate possible negative correlation, different precoding vectors are used in consecutive slots or sub-frames that are transmitted at different frequencies (that is, within the frequency hopping pattern). For example (example a inFIG. 3), for a PUCCH transmission slot0can be transmitted with precoding vector [1 −1 1 −1] and slot1can be transmitted with precoding vector [1 1 −1 −1] (this example may also be viewed as precoding with [1 −1] over antenna groups that are rearranged at the slot boundary). In the case of two transmit antennas (example b) the precoding vectors may be, as one example, [1 1] and [1 −1]. In the case of TDD, the precoding vectors may be derived from DL channel estimates utilizing DL/UL reciprocity. One exemplary advantage of this approach is simplicity, while fulfilling all of the considerations discussed above.

The foregoing options are tabulated inFIG. 3, which shows antenna selections for the case of PUCCH transmission with a UE10having four transmit antennas36, and which has a frequency hopping pattern of two (slot0, slot1).

Discussed now is the PUSCH transmission without frequency hopping. In these cases the UE10may be allocated wideband PUSCH transmissions and/or a SRS providing channel state information on a wide PUSCH bandwidth. However, a discontinuity in the frequency domain response appearing to the Rel-8 eNB12may result in, for example, degradation of the channel estimation and thus is not preferable.

Two main cases are considered below: the LTE-A UE10appears as a Rel-8 UE supporting transmit antenna selection, or the LTE-A UE10appears as a single antenna Rel-8 UE (which is also the case if the Rel-8 eNB does not support UE antenna selection).

Discussed first is the case where the LTE-A UE10appears as a Rel-8 UE supporting transmit antenna selection.

In accordance with the exemplary embodiments of this invention at least two transmission arrangements (options) may be provided.

The following options are made available for use by the UE10.

Option 1: In the first option the UE10selects two of the transmit antennas36to be used, with the antenna selection directed by the eNB12. In the case that more than two transmit antennas are available at the UE10, the UE may alternatively virtualize antennas by grouping transmit antennas36into two antenna groups, and using them as the transmit antennas appearing to the eNB12. Antenna selection can also be seen as a form of precoding with [1 0] and [0 1] as precoding vectors in the two transmit antenna case. One exemplary advantage of this approach is simplicity, while fulfilling most of the considerations discussed above.

Option 2: In this second option the UE10selects two of the precoding vectors for multiple transmit antennas12and uses them as the transmit antennas appearing to the eNB12. For example, precoding vectors of [1 1] and [1 −1] can be used with two transmit antennas36, while precoding vectors of [1 1 1 1] and [1 −1 1 −1] may be used with four transmit antennas. One exemplary advantage of this approach is simplicity, while fulfilling all of the considerations discussed above.

As was noted above, it may be preferred to use precoding vectors having a constant modulus, although the use of precoding vectors with constant modulus is not a requirement to implement the exemplary embodiments of this invention.

Discussed now is the case where the LTE-A UE10appears as a single antenna Rel-8 UE.

In accordance with the exemplary embodiments of this invention at least three transmission arrangements (options) may be provided.

The following options are made available for use by the UE10.

Option 1: In the first option the UE10selects and uses one of the transmit antennas36. One exemplary advantage of this approach is simplicity, while fulfilling most of the considerations discussed above.

Option 2: In the second option, and in the case of TDD, the UE10derives a precoding vector from the DL channel estimates utilizing DL/UL reciprocity and uses the precoding vector for the UL transmission. One exemplary advantage of this approach is simplicity, while fulfilling all of the considerations discussed above.

Option 3: In the third option signals from different transmit antennas36are cyclically delayed relative to the first transmit antenna by an antenna specific delay. The delay is selected so that: (a) the delay does not reduce the coherence bandwidth of the resulting signal (when the signals from the transmitting antennas36are combined) below a typically expected channel coherence bandwidth in the case of single transmit antenna; and (b) the delay spread of the signal arriving at the eNB12is increased by only an acceptable amount when compared to cyclic prefix length. The delay may be predetermined. An exemplary value is 0.5 us.

As opposed to the use of cyclic delay diversity (CDD), the purpose of this third option is not to introduce delay that is sufficient to provide antenna diversity within the expected scheduling bandwidth. Instead, a purpose is to alleviate the impact of antenna correlation by gradually changing the signal phase (in frequency) between transmit antennas36. The gradual change of the signal phase (in frequency) can be performed over the entire bandwidth available at the eNB12for PUSCH. Thus, the signal phase difference between transmit antennas (in frequency) can depend on the location in the frequency of the physical resource scheduled for the UE10. In this case it is the channel sounding and frequency domain scheduling of eNB12that is relied on to schedule the UE12on a frequency where signals from the transmit antennas36combine constructively. One exemplary advantage of this approach is simplicity, while fulfilling all of the considerations discussed above.

In all cases, the SRS is transmitted with the same transmission arrangement that is selected for PUSCH.

Additionally, the signals to different transmit antennas36can be rotated with an antenna specific phase rotator. Reference in this regard can be made toFIG. 4. The phase rotator may be changed between TTIs. The change rate and sign of the rotator is transmit-antenna specific, and the maximum change rate is selected to be sufficiently low so that the coherence time/time correlation of the resulting signal (when the signals from the transmitting antennas36are combined at the eNB12) corresponds to a coherence time/time correlation of a signal received from a low velocity terminal (e.g., one having a velocity of 10 km/h). For example, phase rotators w1, w2, . . . , wNfor N transmit antennas can be defined with wn=exp(jα/N(−1)n└n/2┘) where a is selected to provide the desired coherence time.

In the TDD case, and utilizing channel reciprocity, the precoding vector update rate is preferably selected to be relatively low.

Based on the foregoing it should be apparent that the exemplary embodiments of this invention provide a method, apparatus and computer program(s) to provide a transmission from a multiple transmit antenna user equipment with an appearance, at a receiver, of a transmission made by a single antenna user equipment, or a transmission made by a user equipment that supports antenna switching/selection.

(A)FIG. 5is a logic flow diagram that illustrates the operation of a method, and a result of execution of computer program instructions, in accordance with the exemplary embodiments of this invention. In accordance with these exemplary embodiments a method performs, at Block5A, receiving information descriptive of a type of radio access network in which a user equipment is currently active and, at Block5B, in response to receiving information descriptive of a particular type of radio access network, there is a step of transmitting from a multiple transmit antenna user equipment so that the transmission appears, at a receiver, to have been made by a single antenna user equipment, or by a user equipment that supports antenna switching/selection.

(B) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph, where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink control channel, or on a frequency hopping physical uplink shared channel, and where the step of transmitting further comprises selecting one of the multiple transmit antennas to transmit during a first slot at a first frequency, and another one of the multiple transmit antennas to transmit during a second slot at a second frequency.

(C) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink control channel, or on a frequency hopping physical uplink shared channel, and where the step of transmitting further comprises partitioning the multiple transmit antennas into at least two groups of transmit antennas, each group having at least two transmit antennas, and selecting one of the groups of transmit antennas to transmit during a first slot at a first frequency, and another one of the groups of transmit antennas to transmit during a second slot at a second frequency.

(D) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink control channel, or on a frequency hopping physical uplink shared channel, and where the step of transmitting further comprises selecting a first precoding vector for the multiple transmit antennas for transmitting during a first slot at a first frequency, and selecting a second precoding vector for the multiple transmit antennas for transmitting during a second slot at a second frequency.

(E) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink shared channel, and where the step of transmitting further comprises selecting at least two transmit antennas or at least two groups of transmit antennas and using the selected antennas or antenna groups in accordance with instructions received from a base station such that the user equipment appears to the base station as supporting transmit antenna selection.

(F) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink shared channel, and where the step of transmitting further comprises selecting a first precoding vector for the multiple transmit antennas and selecting a second precoding vector for the multiple transmit antennas and using the selected first and second precoding vectors in accordance with instructions received from a base station such that the user equipment appears to the base station as supporting transmit antenna selection.

(G) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink shared channel, and where the step of transmitting further comprises selecting a single one of the multiple transmit antennas for transmitting to a base station such that the user equipment appears to the base station as having a single transmit antenna.

(H) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink shared channel, and where the step of transmitting further comprises, a time division duplex case, deriving a precoding vector from a downlink channel estimate, and using the derived channel vector for transmitting on a single one of the multiple transmit antennas to a base station such that the user equipment appears to the base station as having a single transmit antenna.

(I) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (A), where the particular type of radio access network is a Rel-8 LTE radio access network, where the transmission is made on a physical uplink shared channel, and where the step of transmitting further comprises cyclically delaying signals from different ones of the multiple transmit antennas, relative to a first transmit antenna, by an antenna specific delay such that the user equipment appears to the base station as having a single transmit antenna.

(J) In the method, and as a result of the execution of computer program instructions as in the preceding paragraph (I), where the antenna specific delay determined such that the delay does not reduce coherence bandwidth of the resulting signal, when the signals from the multiple transmit antennas are combined, below a typical channel coherence bandwidth, and such that a delay spread of the transmitted signal is increased by an acceptable amount when compared to a cyclic prefix length.

(K) In the method, and as a result of the execution of computer program instructions as in the preceding paragraphs, further comprising rotating signals to individual ones of the multiple transmit antennas with an antenna-specific phase rotation, where a change in the rotation rate and sign is selected such that a coherence time/time correlation of the resulting signal, when the signals from the multiple transmit antennas are combined, corresponds to a coherence time/time correlation that would be received from a user terminal moving at a low velocity.

The various blocks shown inFIG. 5may be viewed as method steps, and/or as operations that result from operation of computer program code, and/or as a plurality of coupled logic circuit elements constructed to carry out the associated function(s).

It should thus be appreciated that at least some aspects of the exemplary embodiments of the inventions may be practiced in various components such as integrated circuit chips and modules, and that the exemplary embodiments of this invention may be realized in an apparatus that is embodied as an integrated circuit. The integrated circuit, or circuits, may comprise circuitry (as well as possibly firmware) for embodying at least one or more of a data processor or data processors, a digital signal processor or processors, baseband circuitry and radio frequency circuitry that are configurable so as to operate in accordance with the exemplary embodiments of this invention.

For example, while the exemplary embodiments have been described above in the context of the EUTRAN (UTRAN-LTE) system and the LTE-A 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.

Further, any names used for any described parameters are not intended to be limiting in any respect, as these parameters may be identified by any suitable names. Further, the formulas and expressions that use these various parameters may differ from those expressly disclosed herein. Further, the various names assigned to different channels (e.g., PUCCH, PUSCH, SRS, etc.) are not intended to be limiting in any respect, as these various channels may be identified by any suitable names.