Method and apparatus for efficient precoding information validation for mimo communications

[0001] METHOD AND APPARATUS FOR EFFICIENT PRECODING

INFORMATION VALIDATION FOR ΜΙΜΟ COMMUNICATIONS

[0002] BACKGROUND

[0003] Third generation partnership project 3GPP and 3GPP2 are considering long term evolution (LTE) for radio interface and network architecture. There is an ever-increasing demand on wireless operators to provide better quality voice and high-speed data services. As a result, wireless communication systems that enable higher data rates and higher capacities area pressing need.

[00041 To achieve this, it is becoming increasingly popular to use multiantenna systems in wireless communications networks to obtain the advantages of increased channel capacity, spectrum efficiency, system throughputs, peak data rates, and/or link reliability. Such multi-antenna systems are generically referred to as multiple-input-multiple-output .(ΜΙΜΟ) systems but may also include multiple-input-single-oaitput (MISO) and single-input-multiple-output (S1MO) configurations.

•_[00051_J2ffident,signalingr.is essential-to evolved-universal-terrestrial radio----access (E-UTRA). A low overhead control signaling scheme can improve ΜΙΜΟ link performance, system capacity, system throughputs, information data rates, and increased spectrum, efficiency.

[0006} ΜΙΜΟ systems promise high spectral efficiency and have been

I proposed in many wireless communi cation standards. Research is also currently underway on preceding for spatially multiplexed or space-time coded ΜΙΜΟ systems. Precoding is a technique used to provide increased array and diversitygains.

[0007] Precoding information needs to be communicated from a transmitter (e.g„ abase station) to a receiver (e.g., a wireless transmit/receive unit (WTRU)) to avoid a channel mismatch between transmitting and receiving signals. This is particularly important for ΜΙΜΟ data demodulation when precoding is used.

When a receiver uses incorrect channel responses for data detection, significant performance degradation can occur.

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[0008] Generally, preceding information may be communicated using explicit control signaling, particularly when the transmitter and receiver are restricted to using limited sets of antenna weights and coefficients for precoding. '

The limited sets of antenna weights and coefficients are sometimes referred to as a precoding codebook. Explicit signaling to communicate precoding information from a transmitter to a receiver may incur large signaling overhead, particularly for a large size codebook. Thisisignaling overhead is magnified when frequency ' selective precoding is used.

[0009] Precoding matrix <or antenna weight validation and verification is used to avoid effective channel (mismatch between a transmitter and a receiver.

An effective channel between s. base station and a mobile handset is a channel that experiences the ΜΙΜΟ precoding effect, and is the multiplication of a ί channel matrix Ή and a precoding matrix V used at an evolved Node-B (eNodeB) or a transmitter. A mismatch of the effective channel between the transmitter and the receiver causes severe performance degradation for ΜΙΜΟ !

communication systems.

[0010] Figure IA shows n.precoding.matrix or-antenna weight sigTialinig---------scheme. In a scheme as shown in Figure IA, a wireless transmit/receive unit ί (WTRU) 111 feeds back precoding matrix indices (PMIs) or antenna weights to a base station or an eNodeB 113. Suppose that the WTRU feeds back PMI_j (having Y bits) 116 to the eNodeB 113. To inform the WTRU 111 of the curreUt precoding matrix used at the; eNodeB 113, the eNodeB sends a validation message PMI_k (Y bits) 117 to the WTRU 111. In case of feedback error or override, PMIJ is not equal to PMI_k. In case of no feedback error and no eNodeB override, PMIJ = PMI_L. The validation message can be sent in several

I forms, for example via control signaling or via a reference signal.

[0011] In some systems, such as Wideband Code Division Multiple Access (WCDMA), only one PMI needs to be signaled to the receiver from the transmitter and vice versa. The signals are transmitted in the time domain ' using a spreading code. Signaling the exact single PMI (Y bits) to the receiver does not incur too much overhead as long as the value of Y is reasonable.

J

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However, in some systems, such as orthogonal frequency division multiplexing (OFDM) systems, where the frequency domain is additional to the time domain, there may be multiple PMIs needed to be fed back from the WTRU and sent from the eNodeB for validation to support frequency selective precoding. Frequency selective precoding performs ΜΙΜΟ precoding per sub-band within a system's bandwidth. The entire system'bandwidth can be divided into several sub-bands.

Each sob-band consists of one or several sub-carriers. One precoding matrix is used to precode transmitted data per sub-band. In an extreme case, precoding can be performed per sub-carrier if a sub-band consists of only a sub-carrier. If _; ΐ

multiple PMIs need to be signaled to the receiver, then the signaling overhead could be significant. For example, if there are Z PMIs to be signaled and each

PMI has Y bits, then the total overhead is Z x Y bits. If Z or Y is large, the signaling overhead is significant. '

[0012] The terms precoding matrix and precoding vector are intercom) geabl a and depend upon the number of data streams to be precoded,

[0013] Each PMI is represented by L bits, wherein the value of L depends ί

_upon ΜΙΜΟ configurations, codlabook sizes, and-thenumber-of-data-streams-te-be------supported. WTRUs are assigned resources for communications. A resource block (RB) consists of M (for example, 12) subcarriers. A resource block group (RBG) cr sub-band consists of N resource blocks (N_J£B); for example, N_RB '=* 2,4,5,6,10, :

25, or entire bandwidth. A system bandwidth can have one or more RBGs or subbands depending on the size of die bandwidth and the value of N_RB per RBG .

For example, the number of RBGs per system bandwidth, N_RBG, can be one., two, four, ten, twenty, or fifty, in general, the terms RBG and sub-band are interchangeable.

[0014] The WTRU feeds back one PMI for each RBG that is configured for or selected by the WTRU for reporting. Among the RBGs for a given bandwidth,

N RBGs, where N < N_RBG, can be configured for or selected by a WTRU. If N RBGs are configured for or Selected by a WTRU for reporting precoding information, the WTRU feeds back N PMIs to the eNodeB. The eNodeB sends the precoding validation message comprising N PMIs hack to the WTRU.

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[0015] To inform the WTRU of the current PMIs used at the eNodeB, tlie eNodeB sends N PMIs back tc the WTRU. The total number of bits that the eNodeB sends to the WTRU per PMI validation message is N_PMI x N bits.

[0016] Table 1 shows the number of bits for the PMI validation message assuming N_JPMI = 5 bits. The numbers are summarized for 5,10, and 20 MHz system bandwidth. The second row is NJRB, the number of RBs per RBG. For example, N_RB ranges from 2 to 100 for 20MHz. The third row is N_RBG per¹ system bandwidth, he., the number of RBGs per system bandwidth for 5,10, or

MHz, and the value of NJRBG ranges from 1 to 50. The fourth row is ihe toti il number of bits for PMI validation signaling per validation message or grant channel.

<td></td><td colspan="4"> 5 MHz 300 (rjubcarriers)</td><td colspan="5"> 10 MHz 600 (Bubcarriers)</td><td colspan="6"> 20MHz 1200 (subcarriers)</td>

<td> N_RB per RBG</td><td> 2</td><td> •5</td><td> 10</td><td> 25</td><td> 2</td><td> 5</td><td> 10</td><td> 25</td><td> 50</td><td> 2</td><td> 5</td><td> 10</td><td> 25</td><td> 50</td><td> 100</td>

<td> NJtBQ Per band</td><td> 15</td><td> 5</td><td> 3</td><td> 1</td><td> 25</td><td> 10</td><td> 5</td><td> 2</td><td> 1</td><td> 50</td><td> 20</td><td> 10</td><td> 4</td><td> 2</td><td> 1</td>

<td> Total # of bits for PMI BifTTinlinR per validation</td><td> 65</td><td> 25</td><td> 16</td><td> 5</td><td> 125</td><td> 50</td><td> 25</td><td> 10</td><td> 5</td><td> 250</td><td> 100</td><td> 50</td><td> 20</td><td> 10</td><td> 5</td>

<td> message</td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td><td></td>

<td></td><td colspan="7"> Assume 12 subcarriers per F NJRB: Number of resource t NJRBG: Number of frequen unit to which assigned RBs NJ?Mh Number dibits to re Maximum total number of bi NJRBGxN^FMI</td><td colspan="8"> tB. docks. cy blocks for pre-coding control belong. present a PMI. ts per PMI validation message =</td>

Table 1

[0017] This precoding matrix or antenna weight validation, hereinafter called precoding information validation or PMI validation, may require up to 250 bits or more per validation message. Hence, this scheme is inefficient, [0018] Therefore, it would be desirable to provide a method and apparatus to reduce the signaling overhead for PMI validation.

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[0019] SUMMARY

[0020] A method and upparatus for efficient precoding information validation in a ΜΙΜΟ wireless communications is provided.

[0021] A wireless transmit/receive unit (WTRU) transmits one or multiple precoding information or precoding matrix indices (PMIs) to an eNodeB. In response, the WTRU receives a validation message (a PMI indicator) from the eNodeB including a precoding confirmation message indicating whether or not ' there is a match to the precodimg information reported by the WTRU. If there is a match between the precoding information, i.e., the precoding information js identical, a precoding validation message including a precoding confirmation message is received by the WTR.U from the eNodeB to confirm that the precoding information used at the eNodeB is the same as the precoding information fed _: back from the WTRU. However, if there is a mismatch or if the preceding information fed back from the WTRU is overridden by the eNodeB, the WTRU receives a validation message including a precoding confirmation/indication message from the eNodeB to indicate that the eNodeB does not use the precoding information fed back from the WTRU- The WTRU may-also receive-a-validation-------------message including a precoding indication message from the eNodeB to indicate the precoding information that is being used at the eNodeB. Precoding validation using a precoding confirmation toessage is used to reduce signaling overhead. !

[0022] The eNodeB sends a precoding confirmation message to a WTRU.

The precoding confirmation message can be carried by a PMI indicator which indicates the state of the downlink (DL) precoding validation. The PMI indicator i could be one bit or a bit sequence representing the precoding confirmation state or one or several precoding information states for the precoding validation corresponding to the WTRU preboding feedback. I

[0023] The validation message or PMI indicate»' using precoding confirmation may consist of one or more bits. The PMI indicator helps indicate the precoding information and state used and therefore helps to reduce overhead .

and increase efficiency.

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[0024] BRIEF DESCRIPTION OF THE DRAWINGS

[0025] A more detailed understanding ofthe invention may be had from die following description of a preferred embodiment, given by way of example and to be understood in conjunction with the accompanying drawings, wherein:

[0026] Figure 1A illustrates a precoding matrix or antenna weight signaling scheme;

[0027] Figure IB shows an example block diagram of a transmitter and receiver configured to implement a precoding matrix transmission;

[0028] . Figure 2 illustrates a first embodiment of a signaling scheme (single

PMI validation for single PMI ihedback);

[0029] Figure 3 A illustrates a second embodiment of a signaling scheme for precoding matrix or antenna weight verification (multiple PMI validation for multiple PMI feedback);

[0030] Figure 3B illustrates another embodiment of a signaling scheme for single PMI validation for multiple PMI feedback;

[0031] Figures 4-8 illustrate various PMI validation message schemes;

._[00321_________Figure 9 illustragea-a-control-signaling- scheme- with—a—PMl-------------validation signaling attached;

[0033] Figure 10 illustrates a control signaling scheme with a PMI validation signaling inserted; and

[0034] Figure 11 shows a wireless communication system with multiple Node Bs in commnnication with, various WTRUs.

[0035] DETAILED DESCRIPTION

[0036] When referred to hereafter, the term WTRU includes, but is not limited to, a Wireless TransmitZReceive Unit (WTRU), a mobile station, a fixed or mobile subscriber unit, a pager,¹ a cellular telephone, a personal digital assistant (PDA), a computer, or any other type of ueer device capable of operating in u wireless environment. When referred to hereafter, the term eNodeB includes, but is not limited to, a Node-B, a base etation, a site controller, an access point

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[0037] The term PMI indicator is used to refer to an indicator responding to the feedback signal of or corresponding to the validation state of antenn a weights, PMI, beamforming weights, etc. The PMI indicator may carry a precoding confirmation message, a precoding indication message, other precoding-related messages, ora combination of them. The precoding indication message could be a precoding information indication message, a rank override message, a feedback error message, etc., depending on the state of precoding validation and may indicate -rank information or other precoding related information.

[0038] The methods as described hereafter provide an E-UTRA scheme for antenna weight, beamforming information, precoding information, or precoding matrix indication PMI signaling and validation.

[0039] Figure 16 is a block diagram of a transmitter 110 and a receiver 120 configured to perform a method of precoding matrix indication as described _hereafter. In addition to components jncludedln.aTvpical.tTan8mitter/receiver.-----— transmitter 110 comprises a precoding information determiner 114, a precoding processor 116, an antenna array 118, and a precoding validation message generator 136 comprising a precoding confirmation message block 132 and a precoding indication message htock 134. The precoding information determiner 114 is used to determine precoding information based on the received precoding feedback from the precoding information generator 124 of the receiver 120. The output of the precoding information determiner 114 is used by the precoding processor 116 and the transmitter 110 when transmitting a data transmission, for example, orthogonal frequency division multiplexing (OFDM) symbols, to the receiver 120. The precoding validation message generator 136 is used to generate the validation messagebased on the output ofthe precoding information determiner 114. The precoding validation message generator 136 uses the received precoding feedback signal from the precoding information generator 124 and the precoding information generated from the precoding information

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REPLACEMENT SHEET determiner 114 to determine the state of the precoding validation and to generate the corresponding validation message. For example, if there is a match between the precoding information generated by the precoding information determiner 114 and the precoding information generator 124, a validation message including a precoding confirmation message is sent; otherwise, a validation message including a precoding indication message is sent.

[0040] The receiver 120 comprises a receiver 128, a precoding information generator 124, a channel estimator 130, a demodulator/processor 126, and' a precoding validation message! to preooding information converter 138. The receiver 120 receives an OFDM block from the transmitter 110, perforins channel estimation by the channel estimator 130, and generates precoding information using the precoding information generator 124 that is then sent via antennas 127. The receiver 120 also receives the precoding validation message from the precoding validation message generator 136, detects and decodes the precodirig validation, message, and translates the precoding validation message to precoding information using the precoding validation message to precoding information converter 138. The precoding information at the output niprecoding-vnl id ntinn---message to precoding information converter 138 is fed to the demodulator/processor 126 for ΜΙΜΟ data detection, decoding, and processing. [0041] It is noted that thertransmitter 110 maybe located at a WTRU, at a base station, or both, and the receiver 120 may be located at the WTRU, at the base station, or both.

[0042] A validation message or a PMI indicator using the preending confirmation may consist of a single hit. For example, the precoding confirmation or the PMI indicator can carry two possible validation messages using a single bit. (1) The precoding confirmation message informs the WTRU that the precoding information used at title eNodeB is exactly the same as the preending information fed back from the WTRU. (2) The precoding indication message informs the WTRU that the precoding information used at the eNodeB is not the same as the precoding information fed back from the WTRU.

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[0048] The precoding validation message or the PMI indicator may al so consist of more than one bit. Precoding validation messages may carry one precoding confirmation message and several precoding indication messages. Fbr example, the precoding validation message or PMI indicator can carry several possible messages using more than one bit. (1) The precoding confirmation message informs the WTRU that the precoding information used at the eNodefB is exactly the same as the preceding information fed back from the WTRU. (2)

One of several possible precoding indication messages informs the WTRU that the precoding information used at the eNodeB is not the same as the precoding information fed back from the WTRU and indicates which preceding information is being used at the eNodeB.

[0044] The precoding indication message may indicate the kind of precoding information used if the WTRU precoding feedback has an error, is not reliable, or is overridden by thenNodeB. Furthermore, the precoding indication message may indicate which subset of the precoding information is used if tbe

WTRU's rank information in it® precoding feedback is overridden by the eNodeB.

[0045]__The precoding information or PMI may-contain all, the information-.......

related to ΜΙΜΟ precoding, including rank information. The method as described reduces the overhead for PMI validation by using an efficient validation message that consists of confirmation messages pertaining to the WTRU’s precoding feedback. A validation message may also include an indication message. As an example, a Q-bit validation message or PMI indicator is used. Q can be greater than or equal to one for every PMI indicator. For. example, if a validation message is either one confirmation message or one indication message, then Q=1 bit is sufficient. If the validation message is either one confirmation message or one of the several indication messages, then Q>l. bits may be used.

[0046] The confirmation message and indication message can be separately coded or encoded or jointly coded or encoded. In a separate coding or encoding scheme, the validation message* may consist of two parts - a confirmation parr and an indication part. The confirmation part usually uses one bit to carry ε.

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ITC-2-1683.01.WO REPLACEMENT SHEET positive confirmation message or a negative confirmation message. Hie indication part usually uses one or more bits to carry two or more indication, messages. In the confirmation message, a positive confirmation message is used to inform the WTRU that the precoding information used at the eNodeB is exactly the same as the precoding information fed back from the WTRU. On tlie other hand, a negative confirmation message is used to inform the WTRU that the precoding information used at the eNodeB is not the same as the precoding information fed back from the WTRU. This indicates to the WTRU that different precoding information is being used at the eNodeB. The kind of precodirg information being used at the eNodeB is indicated in the indication part of validation message.

[00471 A separate ceding message format having confirmation and, indication parts or fields is depicted as follows:

<td> Confirmation Message</td><td> Indication. Message</td>

Validation Message.

[00481 In a joint coding fir encoding scheme, the validation message may _„__consistofonlyonepart -that-oembines- confirmation-andindicatiom messages:

Each validation message can carry either one confirmation message (a positive confirmation message) or one of the possible indication messages. The indication message in joint coding serves vwo purposes - to provide negative confirmation and precoding indication at the same time. That is, the indication message is used to inform the WTRU that the preceding information used at the eNodeB i s not the same as the precoding information fed back from the WTRU and it also indicates the precoding inform&amp;tion being used at the eNodeB. A joint coding message format having a single combined confirmation/indication part or field for the validation message is depicted as follows:

Confirmation/indication Messages Validation Message.

[0049] Separate coding or encoding of confirmation and indication messages is simple. In addition; most of the time only the confirmation message or one bit needs to be sent, therefore the efficiency is high. However, the receiver

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REPLACEMENT SHEET has to distinguish between a>confirmation message and a confirmation and indication message because they are of different lengths. This may increase the detection complexity of the receiver. To avoid the issue of different lengths between a confirmation message and a confirmation and indication message, the same format may be used regardless of whether the precoding information of the eNodeB and the WTRU are identical or not. For example, the same format fona confirmation and indication message may be used by a confirmation message. [0050] Furthermore, only one confirmation message and one indication message may be sent, instead of sending one confirmation message and multiple indication messages in the cases of multiple sub-band precoding. The scheme using only one confirmation message and one indication message is a wide-hand precoding or non-frequency selective precoding, since only one indication message is sent corresponding to a single precoding information or matrix that is used at the eNodeB for all the sub-bands. The scheme using one confirmation message and multiple indication messages is a multi-band precoding or frequency selective precoding, since multiple precoding information is used for multiple sub____bands, where each precoding informationis.ufled for.one sub-band. --------------------[0051] By using the same format for both the confirmation only message and the confirmation and indication messages, and using the non-frequency selective precoding when the precoding information used at the eNodeB and the precoding information fed bach, from the WTRU are not identical, detection complexity at receiver is reduced or avoided. When the precoding information used at the eNodeB and the preceding information fed back from the WTRU are identical, multi-band precoding'or frequency selective preceding is used.

[0052] Joint coding combine confirmation and indication messages and can.

save greater bits per validation message. But, every validation message that is sent contains both confirmation and indication messages, and therefore, there are a constant number of bits that are sent consistently in a validation message. The overall efficiency may be lower for joint coding as compared to separate coding, but joint coding may not increase the detection complexity of the receiver. The use of confirmation and indication messages for responding to precoding feedback

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REPLACEMENT SHEET using either the separate or Joint coding or encoding schemes for precoding information provides greater efficiency than the straightforward method, as it uses a very high number of bite.

[0053] As another example, for Q=2 bits, using separate coding for the confirmation and indication messages, the confirmation part of the validation message may use one bit and the indication part of the validation message me y use the other bit. The confirmation part of the validation message with hit 0 me.y represent the positive confirmation message, and bit 1 may represent the negative confirmation message. The indication part of the validation message with bit 0 and 1 may represent indication message 1 and indication message 2, respectively, which may correspondingly indicate a precoding information 1 and precoding information 2.

[0054] For Q=2 bits, using joint coding for the confirmation and indication messages, a validation message with a bit sequence 00 may represent a confirmation message (a positive confirmation message), A validation message with a bit sequence 01,10, or 12 may represent indication message 1, indication message 2, or indication message 3, respectively. wMch-may-correspondingly--indicate a precoding information 1, precoding information 2, and precoding information 3. A validation message with the bit sequence 01, 10, or 11 automatically represents the negative confirmation message, due to the joint coding or encoding of the confirmation and indication messages.

[0055] Similarly for Q=3 hits, when using separate coding for the confirmation and indication messages, the confirmation part of the validation message may use one bit and th® indication part of the validation message may use two hits. The confirmation part of the validation message with bit 0 may represent the positive confirmation message and bit 1 may represent the negative confirmation message. The indication part of the validation message with bits 00-11 may represent indication message number 1 to message number 4, respectively, that indicates the corresponding precoding information numbers 1 to 4. »

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[0056] Similarly for Q=3 bits, when using joint coding or encoding of the confirmation and indication messages, a validation message with a bit sequence.

000 may represent the positive confirmation message. A validation message with, a bit sequence 001 to 111 may represent the negative confirmation message and at the same time represent the indication message number 1 to indication message number 7, respectively, which indicates the corresponding precodir.g information number 1 to preceding information number 7.

[0057] The indication message may indicate additional information. For example, the indication message may indicate one or more of the followinjp which precoding information or matrix is used (this may also include rank information), how the eNodeB‘overrides (e.g., which precoding information or matrix subset should be used) when WTRUs rank in precoding feedback is overridden), or how the eNodeB handles the case when the WTRU feedback is erroneous (e.g., use the previously used valid precodiag information). According to what information is indicated, the indication message may have different types, e.g., a precoding information indication type message, a precoding or rank ' override message, a feedback error message, etc. _ AccordingLy,_the. validation----message may have two types - a confirmation message and an indication message as summarized in Table 2A.

<td> Type of Validation Message</td><td> Usage</td>

<td> Confirmation message</td><td> Confirm the same precoding information fed back from the WTRU is used at the eNodeB.</td>

<td> Indication message</td><td> Indicate the precoding information used at the eNodeB.</td>

Table 2A

[0058] A validation message may have four types of messages - a confirmation message, an indication message, an override message, and a feedback error message as summarized in Table 2B.

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<td> Type of Validation Message</td><td> Usage</td>

<td> Confirmation message</td><td> Confirm the same precoding information fed back from foe WTRU is used at the eNodeB.</td>

<td> Indication message</td><td> Indicate the precoding information used at the eNodeB.</td>

<td> Override message</td><td> Indicate the eNodeB overrides the WTRU s feedback. If it is a rank override, indicate which precoding information subset should be used.</td>

<td> Feedback error message</td><td> Indicate the WTRtFs feedback is in error.</td>

Table 2B

[0059] The method as described above is applicable to any ΜΙΜΟ wireless communication system and is applicable to the uplink (UL) and the downlink (DL).

[0060] In general there can be one confirmation message, Ml indication mesBageg' (indi'catirigdifFefent^: precoding information), M2 override messages (indicating different override rules for precoding), and M3 feedback error messages (indicating different precoding rules to handle feedback error). The total number of bits to represent the validation message is logs (1+M1 + M2 + M3).

[0061] Joint coding may t be performed for the precoding confirmation message, precoding information, or indication messages which may or may not include rank information. In addition, joint coding may also be performed for rank override messages, feedback error messages, or other M1M0 related information and messages if used.

[0062] An implementation of the above scheme using either a single bit or more bits is described as follows. When there is a match between the PMIs, i.e. the PMIs are identical, only a PMI indicator is received by the WTRU. Alternatively, a PMI indicator with the PM1 of the eNodeB can also be received

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ITC-2-1683.01.WO REPLACEMENT SHEET by the WTRU. However, if there is a mismatch between the PMIs or if the PMIs of the WTRU are overridden, the WTRU receives a PMI indicator with the PMI of the eNodeB. In this example, the PMI indicator is a precoding confirmation field and the PMI is a precoding indication field.

[0063] A plurality of PMKs may be sent simultaneously, and the PMIs may be partitioned into a plurality nf groups.

[0064] Figure 2 depicts a signaling scheme in accordance with another embodiment. A WTRU or a receiver 211 transmits a PMI or antenna weights to an eNodeB or transmitter 213.wienoted as PMI j (having Yhits) 215. To inform the WTRU 211 of the currentlymsed precoding matrix or antenna weights at the eNodeB 213, the eNodeB 213 Bends a validation message back to the WTRU 211, denoted as PMI_k (Y bits) 217, When the eNodeB 213 and the WTRU 211 use the same precoding matrix or antenna weights, the eNodeB 213 sends only a PMI indicator, PMI.IND (one bit) 217, indicating that the precoding matrix or the antenna weights are identical/ instead of sending the entire PMI or antenna weights bits. The feedback error is usually small, typically 1%. Most ofthe time, ^:_the eNodeB 213 and the WTRU 211 use thejame precoding-matrixor antenna-----weights. Therefore, most of ihe time, the one bit PMI indicator (positive confirmation or negative confirmation messages) is sent.

[0065] This signaling scheme significantly reduces the signaling overhead and is summarized as follows. When the PMI indicator, the PMI, or the antenna weight indicator is set at 1, it indicates a negative confirmation message and that the PMI or antenna weights used at the eNodeB and the WTRU are not identical.

This usually occurs in the event of a feedback error or if the eNodeB overrides the WTRUs feedback.

[0066] When the PMI indicator, the PMI, or the antenna weight indicator is set at 0, it indicates a positive confirmation message and that the PMI or antenna weights used at the eNodeB and the WTRU are identical. This usually occurs in the event of no feedback error and if the eNodeB does not override the WTRUs feedback. This scheme is summarized in Tables 3A and 3B. The PMI'. indicator is denoted by PMUND.

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<td> PMIJND</td><td> State</td><td> Usage</td>

<td> 0</td><td> Confirmation (or positive confirm)</td><td> Confirm the eNodeB to use the precoding information fed back from the WTRU.</td>

<td> 1</td><td> Not confirm (or negative confirm)</td><td> The eNodeB uses different precoding information than those fed back from the WTRU. This is usually due to a feedback error or an eNodeB override. This could also be due to other factors.</td>

Table 3A; PMI indicator using 1 bit.

<td> PMI_IND</td><td> Message</td><td> Usage</td>

<td> 0</td><td> Positive confirmation message</td><td> Confirm to use PMI_n fed back from the WTRU.</td>

<td> η</td><td rowspan="2"> • Negativeconfirmation— message</td><td rowspan="2"> SendsinglePMI.-Seiid PMTmwhichris a precoding matrix used at the eNodeB for all the sub-bands or RBGs, i.e., ;the same single precoding matrix is used for entire system bandwidth.</td>

<td></td>

Table 3B:. Non-Frequency Selective Precoding,(for non-frequency selective feedback or single PMI feedback)

[0067] The PMI indicator! may also be used to indicate the beamforming matrix/matriceg or vectors, antenna weights, and any other matrix, vector, or weights when applicable. Other notations for the PMI indicator other than PMI_IND may also be used. The bit assignment for the PMIJND is arbitrary and any other values than '1' arid '0' may be used for the PMI indicator.

[0068] Figure 3A shows ; a signaling scheme for precoding matrix or antenna weight validation in;accordance with another embodiment. This embodiment is for an efficient signaling for multiple PMI validation ο:.

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For example, the entire system bandwidth may be divided into multiple subbands (or RBGs) and one PMI ntay be reported for each sub-band when there are multiple PMIs to be reported for the entire bandwidth. In this embodiment, there can be N PMIs for reporting.

[0069] A WTRU or receiver 311 transmits precoding matrix indices er antenna weight information 315 to an eNodeB or transmitter 313, denoted ss PMI_jl, PMI_j2, .., PMXjN. To inform the WTRU 311 of the currently used precoding matrices or antenna weights at the eNodeB 313, the eNodeB 313 sends a validation message 317 back to the WTRU 311, denoted as PMI_kl, PMI_k!i,

.., PMIJkN which corresponds to precoding feedback PMIJ1, PMIJ2 PMIJN respectively.

(0070] When the eNodeB;313 and the WTRU 311 use the same precoding matrices or same sets of antenna weights for. all the sub-bands, (i.e., PMI_jl=.

PMI_kl, PMI j2= PMI_k2,.., PMIJN= PMIJkN), the eNodeB 313 sends only a PMI indicator (1 bit) indicating that the PMIs are identical, instead of sending ail _ the PMIs or all sets of antenina weights_bit8^back-to^the.WTRU . 311__This------------feedback error is usually small»: typically 1%. Most of the time, the eNodeB 313 and the WTRU 311 use the same precoding matrices or antenna weights.

[0071] In case of no feedback error and no override, the eNodeB 313 sends only the PMIJND to the WTRU 311. In case of a feedback error or precoding or rank override, the eNodeB S13 sends the PMIJND and the precoding information to the WTRU 311. Depending on whether frequency selective precoding is used or not, the eNtodeB 313 sends a different amount of precoding information to the WTRU 311. For example, if frequency selective precoding is used at the eNodeB 313, the 'eNedeB sends the PMIJND and PMIJlL, PMI_k2,

.., PMI_kN to the WTRU 311, where PMI_kl, PMIJL2,.., PMI_kN represent N precoding matrices for N sub-bands or RBGs. If non-frequency selective precoding is used at the eNodeB 313, the eNodeB sends the PMIJND and a single precoding information PKDJm, where PML_m is a precoding matrix used

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<td> PMI_ENU</td><td> Message</td><td> Usage</td>

<td> 0</td><td> Positive confirmation message</td><td> Confirm to use PMIjl, PMIj2,.., PMIj.N fed back from the WTRU.</td>

<td> 1</td><td> Negative confirmation message</td><td> Send N PMIs. (Send PMIJtl, PMI_k2,..,PMI_kN.) N precoding matrices are used for N subbands.</td>

Table 4: Frequency Selective Precoding when positive and negative confirmation (for frequency selective feedback or multiple PMIs feedback)

<td> PMIJND</td><td> Message</td><td> Usage</td>

<td> 0</td><td> Positive confirmation message</td><td> Confirm to use PMIjl, PMI_j2, ..,PMIjN fed back from the WTRU.</td>

<td> 1</td><td> Negative confirmation message</td><td> Send a single PML Send PMI_m which is -aprecodingmatrixusedatthe~eNodeB for all tiie sub-bands or RBGs, i.e., the same single precoding matrix is used for tbe entire system bandwidth.</td>

Table 5: Frequency Selective Precoding when Positive Confirmation and NonFrequency Selective Precoding When Negative Confirmation (for frequency selective feedback or multiple PMIs feedback)

[0072] Figure 3B shows &lt; a signaling scheme for precoding matrix or , antenna weight validation in accordance with another embodiment. This embodiment is for an efficient signaling for multiple PMI feedback and a validation message including a single precoding indication message. A WTRU or receiver 311 transmits precoding matrix indices or antenna weight information

316 to an eNodeB or transmitte® 313, denoted as PMIjl, PMlj2,.. PMIJN. To inform the WTRU 311 of the currently used precoding matrices or antenna weights at the eNodeB 313, the eNodeB sends a validation message 318 back to

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ITC-2-1683.01.WO REPLACEMENT SHEET the WTRU 311, denoted aa PMIJND + PMI_k, which responds to precoding feedback PMI jl, PMIJ2,..,PMIjN. This is used when there is multiple PMI feedback and a validation message with a single PMI indication message is used.

[0073] When the eNodeB 313 and the WTRU 311 use the same preceding matrices or same sets of antenna weights, the eNodeB 313 sends a confirmation message indicating that the PMIs are identical, instead of sending all the PMIs or all sets of antenna weight# bits back to the WTRU 311. Otherwise, the eNodeB 313 sends an indication message to the WTRU 311 indicating that the

PMIs are not identical. If separate coding is used, PMIJND and PMI are sent, io which the PMIJND serves as a positive or negative confirmation message and the PMI serves as the indication message. In this case, PMIJND is one bit and

PMI is at least one bit. If joinil coding is used, the PMI_IND contains the PMI, and the PMI_IND serves as both a positive or negative confirmation message and an indication message. In this «case, PMIJND is at least one bit.

[0074] The validation message format with two fields can be depicted as follows:

<td> ££OJND-</td><td> JPMI </td>

Validation Message Format 1

[0075] For a validation message using joint coding of confirmation and indication messages, the validation message format with a single field can he depicted as follows:

PMIJND

Validation Message Format 2

[0076] In validation message format 2, the single PMIJND field contains the combined information of the» PMIJND and the PMI as in validation message format 1.

[0077] Another implementation is to use a default precoding message instead of sending an indication message or PMIs. The signaling can be done in another way, wherein there is no feedback error and no override. The eNodeB sends only the PMLIND (positive confirmation message) to the WTRU, in which the PMI„IND confirms that thei eNodeB uses the same precoding information fed

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ITC-2-1683.01.WO REPLACEMENT SHEET back from the WTRU. In the case of feedback error or PMI override, the eNodeB sends the PMLJND (negative confirmation message) to the WTRU, in which the

PMIJDNTD informs the WTRU io use the default or pre-determined precoding indication message or information. Therefore, only the PMI_IND containing the confirmation message is Bent, while the indication message or PMI(s) are not sent in any. case. This scheme is summarized in Table 6.

<td> PMIJND</td><td> Message</td><td> Usage</td>

<td> 0</td><td> Positive confirmation</td><td> Use precoding information fed back from the WTRU.</td>

<td> 1</td><td> Negative confirmation</td><td> Use the default or predetermined precoding indication message or information.</td>

Table 6: Negative confirmation using default precoding indication message.

[0078] The confirmation &amp;tate for the PMIJND as positive and negative is arbitrary and any other values» than positive and negative may be used for the PMI indicator.

[0079] As described earlier, the signaling overhead for the PMI validation or verification may require up to 250 bits or more per validation signaling in the case of multiple RBGs and multiple PMIs each time PMI validation messages are sent. Therefore, the signaling scheme using the precoding confirmation message as described saves a significant) amount of signaling overhead.

[0080] The downlink PMI indicator signaling scheme in accordance with another embodiment is summarized as follows. When the PMI_IND (the PMI or antenna weight indicator) is net at 1, it indicates a negative confirmation message and that at least one of a plurality of PMIs used at the eN odeB 313 and . the WTRU 311 are not identical. This usually occurs in the event of feedback errors or when the eNodeB 313( overrides the WTRU’s 311 feedback. All PMIs are sent following the PMI_INI) (1 bit) as shown in Figure 4. In Figure 4, the first element is PMI_IND 411 followed by individual PMIs 413(a) to 413(n). [0081] When the PMI_IND (the PMI or antenna weight indicator) is set at

0, it indicates a positive confirmation message and that all of the PMIs used at

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PCT/US 2008/061 051 - 18-02-2009 REPLACEMENT SHEET the eNodeB 313 and the WTRU 311 are identical. This usually occurs in the event of no feedback error and the eNodeB 313 does not override the WTRU's feedback! PMIs are not sent, but only the PMIJIND (one bit) 411 is sent.

[0082] In accordance with another embodiment, PMIs are partitioned into groups, for example, G groups,. As shown in Figure 5, each group has one bit in indicate whether the precodingimatrices or antenna weights are the same for the eNodeB 313 and the WTRU 311. Such signaling can he implemented to have either Q bits in one indicator or»Q PMI indicators each of which has one bit. PMI ;

indicators, PMIJNW) 511, PMLIND(2) 513,.., and PMIJND(G) 51g, may be spread over the validation messages as shown in Figure 5.

[0083] An alternate mod&amp; of grouping can be seen in Figure 6, wherein the

PMI indicators (611, 613, and 61g), PMI_IND(1), PMI_IND(2), .., and PMI_IND(G), may be grouped in the front portion of the validation message as shown in Figure 6.

[0084] The signaling mechanism in accordance with PMI indicators (PMLINDig), g=l,2,..,G) for group PMIs, is summarized as follows. When the „ 1 ._PMUND (the PMI or antenna weight indicator) fona eroup.oTWTKUsis set^e t------------—

1, it indicates a negative confirmation message and that at least one of the PMIs belonging to that group that are used at the eNodeB 313 and the WTRU 311 are not identical. This usually occurs in the event of feedback errors or if the eNodeB overrides the WTRU's feedback for that PMI group. If PMIJLMD (g) = l, indicating a negative confirmation message for the g^^{* 1} group, then all the PMIs belonging to the g⁰* group are'Sent following the PMLIND (g) that is set to 3.

For example, in Figure 5, if any of PMI_1, PMI_2, and PMI_3 are not the same for the eNodeB and the WTRU, then PMI_IND(1), PMI_1, PMI_2, and PMI_3 are sent by the eNodeB.

[0085] When the PMIJNiD, the PMI, or the antenna weight indicator for a group of WTRUs is set at 0, it indicates a positive confirmation message and that ΐ all of the PMIs belonging to that group that are used at the eNodeB and the i

WTRU are identical. This usually occurs in the event of no feedback error or if the eNodeB does not override¹ the WTRU's feedback. If PMIJNIXg) = 0, j

l

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ITC-2-1683.01.WO REPLACEMENT SHEET indicating a positive confirmation message for the g^¹ group, then PMIs belonging to the g*¹¹ group are not sent, biit only the PMI indicator for the g* group is sec t.

The sent PMLJND(g) is set to 0. For example, in Figure 6, if all of PMI_4,

PMI_5, and PMI_6 are the same for the eNodeB and the WTRU, only the 1-bit

PMI_IND(2) is sent by the eNfodeB. Alternatively, the fields reserved for the unsent PMIs can be used for sending other information or data. This increases the information or data throughput and spectrum efficiency. For example, the fields reserved for PMI_4, PMIJ5, and PMI_6 can be used for sending other ' information or data.

[0086] A special case for group PMI indicator signaling is when each group has only one PMI, i.e., G=N. Intthis implementation, each group has exactly one PMI. This scheme is illustrated in Figure 7. An increase in the groups (G) may increase the signaling efficiency because only a few PMIs which are not identical need to be signaled.

[0087] In general, the PMIJND can represent the messages or states that consist of a bit sequence. For examp] e, the PMIJND can represent the precoding {_confirmation message or state, precoding information-message-l-or-state-l.,----------------uprecoding information message 2 or state 2, and so on. This scheme is summarized in Table 7A A similar scheme in case of ah override scheme is shown in Table 7B.

<td> PMIJND</td><td> Message (state*</td><td> Usage</td>

<td> 000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 001</td><td> Precoding information message#l</td><td> Inform the WTRU to use precoding matrix 1.</td>

<td> 010</td><td> Precoding information message#2</td><td> Inform the WTRU to use precoding matrix 2</td>

<td></td><td> ..</td><td></td>

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<td> 110</td><td> Precoding information message#6</td><td> Inform the WTRU to use precoding matrix 6</td>

<td> 111</td><td> Precoding information message #7</td><td> Inform the WTRU to use precoding matrix 7.</td>

Table 7A

<td> PMIJND</td><td> Message</td><td> Usage</td>

<td> 000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed hack from the WTRU.</td>

<td> 001</td><td> Precoding information message#l</td><td> Inform the WTRU to use precoding matrix 1.</td>

<td> ..</td><td></td><td> .</td>

<td>----</td><td> -Rank-information—- - override message#l</td><td> Informthe-WTRUtouseprecodingsub-— matrix 1</td>

<td> 111</td><td> Rank information override message#^</td><td> Inform the WTRU to use precoding submatrix 2</td>

Table TB. With rank override

[0088] As an example, codebook (1) using the above scheme has four precoding vectors for rank 1 and two precoding matrices for rank 2. There are six precoding matrices/vectors in total in codebook (1) as shown in Table 8.

<td> Rgnk 1</td><td> Rank 2</td>

<td> Cl</td><td> C5</td>

<td> C£</td><td> C6</td>

<td> C£</td><td></td>

<td> C4</td><td></td>

Table 8: Codebook (1)

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[0089] A corresponding’i PMI confirmation and indication scheme to codebook 1, when the rank is jointly indicated, can be seen in Table 9A.

<td> PML.IND</td><td> Message</td><td> Usage</td>

<td> 000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 001</td><td> Precoding information or indication message# 1</td><td> Inform the WTRU to use precoding matrix Cl.</td>

<td> ..</td><td> ..</td><td> ..</td>

<td> 101</td><td> Precoding information or indication message#5</td><td> Inform the WTRU to use precoding matrixCS.</td>

<td> 110</td><td> Precoding information or indication message#6</td><td> Inform the WTRU to use precoding matrix C6.</td>

<td> 111</td><td> Reserved</td><td> Reserved or used for other purposes.</td>

Table 9A: PMI confirmation and indication scheme

[0090] Another scheme for codebook (1) using the above scheme, when thia rank is j ointly indicated and a rank override is indicated, uses the corresponding PMI confirmation and indication scheme table for rank 1, as shown in Table 9E.

<td> PMI_IND</td><td> Message</td><td> Usage</td>

<td> 000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 001</td><td> Precoding information or indication message# 1</td><td> Inform the WTRU to use precoding matrix Cl.</td>

<td> 010</td><td> Precoding information or indication message#2</td><td> Inform the WTRU to use precoding matrix C2.</td>

<td> ..</td><td> ..</td><td> ..</td>

s

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<td> 110</td><td> Precoding information or indication mesaage#6</td><td> Inform the WTRU to use precoding matrix C6.</td>

<td> 111</td><td> Rank information override message </td><td> Inform the WTRU to use the precoding matrix subset of a higher rank precoding matrix.</td>

Table 9B: Joint Coding for Precoding Confirmation, Indication and Rank

Override Messages

[0091] A PMI_IND = 111 as used in Table 9B indicates that the eNodeiB informs the WTRU to use the precoding matrix subset of a higher rank precoding matrix. For example, a rank 2 precoding matrix consists of two column vectors and a rank 1 precoding matrix is a precoding vector. When the rank information is overridden from rank 2 to rank 1, either the first or the second column vector of the rank 2 matrix can be indicated to be used.

[0092] Another scheme for codehook (1) using the above scheme, when the rank is separately indicated, isito use the corresponding PMI confirmation and indication scheme table for rank 1, as shown in Table 10A.

<td> ^PNHJNTT</td><td> Message</td><td> Usage</td>

<td> 000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 001</td><td> Precoding information or indication message# 1</td><td> Inform the WTRU to use precoding matrix Cl.</td>

<td> 010</td><td> Precoding information or indication message#2</td><td> Inform the UTRU to use precoding matrix C2.</td>

<td> 011</td><td> Precoding information or indication messhge#3</td><td> Inform the WTRU to use precoding matrix C3.</td>

<td> 100</td><td> Precoding information or indication message#4</td><td> Inform the WTRU to use precoding matrix C4.</td>

<td> 101-111</td><td> Reserved</td><td> Reserved or used for other purposes.</td>

<td> Table 10A:</td><td colspan="2"> ?MI confirmation and indication scheme for Rank 1 with respect to</td>

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[0093] For rank 2, corresponding to codebook (1), the PMI confirmation an d indication scheme table, whenihe rank is separately indicated, can be as shown in Table 10B.

<td> PMI.IND</td><td> Message</td><td> Usage</td>

<td> 00</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 01</td><td> Precoding information or indication message# 1</td><td> Inform the WTRU to use precoding matrix C5.</td>

<td> 10</td><td> Precoding information or indication message#2</td><td> Inform the WTRU to use precoding matrix C6.</td>

<td> 11</td><td> Reserved</td><td> Reserved or used for other purposes.</td>

Table 10B - PMI confirmation and indication scheme for Rank 2 with respect to Codebook (1).

[00941 As an example, codebook (2) has sixteen precoding vectors for rank 1 and“axteen precoding matrices for rank 2, 3) and 4. There are sixty four precoding matrices/vectors in total in codebook 2 as shown in Table 11. The rank 1 precoding matrix is a column vector and includes precoding matrices C1-C1G. The rank 2 precoding matrix i consists of two column vectors and includes precoding matrices C17-C32. The rank 3 precoding matrix consists of tbrea column vectors and includes matrices C33-C48. The rank 4 precoding matrix consists of four column vectors'and includes matrices C49-C64. The precoding matrix for a lower rank is a subset of the precoding matrix in a higher rank. For instance, Cl is a subset of C17, which is a subset of C33, which is a subset of C4S.

<td> Rank 1</td><td> Rank 2</td><td> Rank 3</td><td> Rank 4</td>

<td> Cl</td><td> C17</td><td> C33</td><td> C49</td>

<td> C2</td><td> CIS</td><td> C34</td><td> C50</td>

<td> C3</td><td> C19</td><td> C35</td><td> C51</td>

<td> C4</td><td> C20</td><td> C36</td><td> C52</td>

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<td> C5</td><td> C21</td><td> C37</td><td> C53</td>

<td> C6</td><td> C22</td><td> C38</td><td> C54</td>

<td> C7</td><td> C23 .</td><td> C39</td><td> C55</td>

<td> C8</td><td> C24</td><td> C40</td><td> C56</td>

<td> C9</td><td> C25</td><td> C41</td><td> C57</td>

<td> CIO</td><td> C26</td><td> C42</td><td> C58</td>

<td> Cll</td><td> C27</td><td> C43</td><td> C59</td>

<td> C12</td><td> C28</td><td> C44</td><td> C60</td>

<td> C13</td><td> iC29</td><td> C45</td><td> C61</td>

<td> C14</td><td> C30</td><td> C46</td><td> C62</td>

<td> C15</td><td> C31</td><td> C47</td><td> C63</td>

<td> C16</td><td> C32</td><td> C48</td><td> C64</td>

Table 11: Codebook 2

[0095] A corresponding table for the PMI confirmation and indication scheme for Codebook (2) can baas shown in Table 12A.

<td> PMIJND-</td><td> ---Message</td><td> “Usage</td>

<td> 0000000</td><td> Preceding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 0000001</td><td> Precoding.feedbadk error message</td><td> Inform the WTRU to use precoding matrix X.</td>

<td> 0000010</td><td> Precoding information override message</td><td> Inform the WTRU to use precoding matrix Y.</td>

<td> 0000011 - 0010010</td><td> Precoding information or indication message# 1 - 64</td><td> Inform the WTRU to use precoding matrix Cl to C64, respectively.</td>

<td> 0010011 - 1111111</td><td> Reserved</td><td> Reserved or used for other purposes.</td>

<td> Table 12A:«</td><td colspan="2"> oint Coding for Preboding Confirmation, Indication, Feedback Error</td>

and Override Messages.

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[0096] A corresponding table for the PMI confirmation and indication scheme with rank overriding for Codebook (2) can be as shown in Table 12B.

<td> PMI_IND</td><td> Message</td><td> Usage</td>

<td> 0000000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 0000001</td><td> Precoding feedback error message</td><td> Inform the WTRU to use precodingr matrix X.</td>

<td> 0000010</td><td> Precoding information override message</td><td> Inform the WTRU to use precoding; matrix Y.</td>

<td> 0000011 - 0010010</td><td> Precoding information or indication message 1-64</td><td> Inform the WTRU to use precodingimatrix Cl to C64, respectively.</td>

<td> 0010011 - 0010110</td><td> Rank information override from rank 4 to rank 3</td><td> Inform the WTRU to use four precniing matrix subsets respectively.</td>

<td> 0000111 - -0011100</td><td> Rank information -overridefromrank^— to rank 2</td><td> Inform the WTRU to use six precoding -matrix-subsets-respectively, ......</td>

<td> 0.011101 - 0100000</td><td> Rank information override from'rank 4 to rank 1</td><td> Inform the WTRU to use four precoding matrix subsets respectively.</td>

<td> 0100001 - 0100010</td><td> Rank information override from rank 3 to rank 2</td><td> Inform the WTRU to use three precoding matrix subsets respectively.</td>

<td> 0100100 - 0100110</td><td> Rank information override from rank 3 to rank 1</td><td> Inform the WTRU to use three preceding matrix subsets respectively.</td>

<td> 0100111 - 0101000</td><td> Rank information override from rank 2 to rank 1</td><td> Inform the WTRU to use two precotitng matrix subsets (select the first or the second column vector) respectively.</td>

I

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<td> 0101001 - 1111111</td><td> Reserved</td><td> Reserved or used.for other purposes.</td>

Table 12B: Joint Coding for Precoding Confirmation, Indication, Rank Override and Feedback Error Messages

[00971 To save the signaling overhead, one of the precoding matrices can be removed from the codebook (2). As an example, if C64 or one of the other matrices is removed, then the scheme reduces to the scheme as shown in Table 12C.

<td> PMIJND</td><td> State</td><td> Usage</td>

<td> 000000</td><td> Precoding confirmation message</td><td> Confirm that the eNodeB uses the precoding information fed back from the WTRU.</td>

<td> 000001- 111111</td><td> Precoding infbrmation or indication message 1-63</td><td> Inform the WTRU to use precoding matrix Cl to C63, respectively.</td>

Table-12G:—Modified JointCoding-for-PrecodingGonfirmatdon-aiidTndication------Messages.

[00981 When each group has only one PMI (the PMI or antenna weight indicator) and the PMIJND is Set at (n) = 1, it indicates that the η^Λ PMI that is used at the eNodeB and the WTRU are not identical. This usually occurs in the event of feedback errors or if the eNodeB overrides the WTRU's feedback. Then⁰* PMI is sent. For example, in Figure 8, if PMI_n is not the same for ihe eNodeB and the WTRU, PMI_IND(n) and PMI_n are sent by the eNodeB. This increases signaling efficiency,

[0099] When each groupihas only one PMI (the PMI or antenna weight indicator) and the PMIJND is set at n = 0, it indicates that the PMIs that are used at the eNodeB end if the WTRU are identical. This usually occurs in the event of no feedback error and if the eNodeB does not override the WTRU’s feedback. The η^Λ PMI is not sent, but only the PMIJND for the nth PMI, i.e.,

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PMI_IND(n) is sent. For example, in Figure 8, if PMI_n is the same for the eNodeB and the WTRU, only the l-bit PMIJNIXn) is sent by the eNodeB.

[00100] A PMI indicator may he sent along with, attached to, or embedded in the existing control signaling. Figure 9 shows that PMI validation signaling is attached to a control signaling.Figure 10 shows that PMI validation signaling is inserted in a control signaling! Alternatively, the PMI indicator may be sent using a separate signaling or a* stand alone signaling.

[00101] The PMI validation messages may be signaled to the WTRU via control signaling or a dedicated reference signal (RS). Alternatively, part ofthe validation message may be sent via control signaling and part ofthe validation message may be sent via a dedicated reference signal. For example, the precoding confirmation part may be sent via control signaling and the preceding indication part may be sent via dedicated reference signal. The PMI indicator signaling may be applied to both the control signaling and the dedicated reference signal and be used to reduce the amount of control signaling overhead or dedicated RS overhead. Whea dedicated reference signals are used to send the . __EMZLvalidationjrnessages^several formsTor dedicated reference signals-inay be---------used, such as precoded pilots. The use of the PMI indicator to reduce dedicated.

RS is described as follows.

i '. .

[00102] New downlink PIMt indicator signaling for dedicated reference signal

[00103] When the PMI_IND is set to 1 (a negative confirmation message), it indicates that at least one of the multiple PMIs used at the eNodeB and the WTRU are not identical. This usually occurs in the event of feedback errors or if the eNodeB overrides the WTRU's feedback. All dedicated reference signals that cany PMIs are sent by the eNodeB. The PMI_IND is set to 1 and is also sent by j . I the eNodeB. |

[00104] When the PMI_IND is set to 0 (a positive confirmation message), it !

indicates that all of the multiple PMIs used at the eNodeB and the WTRU are J identical. This usually occurs ir. the event of no feedback error and if the eNode/3 ;

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62/18/2009 13:58 FAX 2155686400 rrC-2-1683.01.WO does not override the WTRlTs^{* 1} feedback. All dedicated reference signals that carry PMIs are not sent by the eNodeB, but only the 1-bit PMIJND that is set to 0 is sent by the eNodeB.

[00105] Most of the time, nil of the multiple PMIs used at the eNodeB and the WTRU are identical and dedicated reference signals are not transmitted, but only the 1-bit PMIJND that ia set to 0 is sent by the eNodeB. Therefore, this signaling scheme significantly reduces the overhead of dedicated reference signals.

[00106] PMI indicator signaling may be applied to both single user (SU)

ΜΙΜΟ and multi-user (MU) ΜΙΜΟ for reduced signaling overhead. In SU- j

ΜΙΜΟ, only the PMI indicator! for one WTRU is sent by the eNodeB in a subband or a frequency and time resource. In MU-MIMO, multiple PMI indicators for multiple WTRUs that share the same sub-band or the same frequency and time resource are sent by the eNodeB. It is, therefore, a simple extension from SU-MIMO, ‘

[00107] In MU-MIMO, it is assumed that K WTRUs exist. An eNodeB sends multiple PMI validation sjgnals eachnfwhich has one or multiple EMls for-eadi----WTRU (WTRU 1, WTRU 2, .., WTRU K). The eNodeB sends multiple PMI indicators to the WTRUs. Each WTRU receives one PMI indicator if no group PMI is used as shown in Figured, or multiple PMI indicators if group PMIs are used for the WTRU as shown in Figures 5-8.

[00108] In the case that the PMIs are the same at the eNodeB and the k^th

WTRU, the eNodeB sends a 1-bit PMI indicator to the k* WTRU. In case that the PMIs are not the same for the eNodeB and the k* WTRU, the eNodeB sende j the PMI indicator denoted by PMIJND⁰⁰ and PMIs denoted by PMFW of the k^ta j

WTRU to the k* WTRU.

[00109] For example, if the PMIs are not the same for the eNodeB and the first WTRU, but the same for ail other WTRUs, then the 1-bit ΡΜΙ_ΙΝΓ>⁽¹⁾ an«l ΡΜΓ^υ are sent to the first WTRU by the eNodeB and the 1-bit PMI_IND^tk) for j

I k=2,3,..,K are sent to all other. WTRUs by the eNodeB. Alternatively in MUMIMO, the eNodeB sends multiple PMI indicators, each for one group of WTRUs.

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The eNodeB may also send one PMI indicator for all WTRUs. For MU-MIMO, the precoding schemes and usage can be generalized as described earlier. [00110] For two users simultaneously supported in the same RB or RBG, it is assumed there is one stream per user, Le., each WTRU sees a rank 1 transmission for itself. Further suppose there are eight beamforming vectors C1, C2, .., C8 in the beamforming codebook. Table 13 describes this scheme: If PMIJND = 0 (a positive confirmation message), it indicates that the eNodeB confirms that the WTRU’s feedback is used at the eNodeB (Cdemrwi). A 3-hit PMI indicates seven possible interfering beamforming vectors of the other user, Cj, j-l,2,..,8 andCj^Cdcidred. One bit combination (111) is reserved. If PMIJND = 1, it indicates that the eNodeB will not use the WTRU’s feedback and a different beamforming vector will he used. A 3-bit PMI indicates eight possible beamforming vectors (Cj, j=l,2,..,8) for the desired user. There is no separate indication for an interfering beamforming vector unless the signaling overhead is allowed to increase.

<td rowspan="2"> PMIJND (1 bit) (Confirmation^ Message)</td><td colspan="2"> PMI (3 bits)</td>

<td colspan="2"> --------------------------(IifdieataaaTMessages)</td>

<td rowspan="2"> 0</td><td> 000 -110</td><td> Qf for j=l,2,..,8, and Cj Cdedred</td>

<td> 111</td><td> Reserved</td>

<td rowspan="8"> 1</td><td> 000</td><td> Cl</td>

<td> 001</td><td> C2</td>

<td> 010</td><td> C3</td>

<td> Oil</td><td> C4</td>

<td> 100</td><td> C5</td>

<td> 101</td><td> C6</td>

<td> no</td><td> C7</td>

<td>¹¹¹</td><td> C8</td>

Table 13; Separate Coding for Confirmation and Indication Messages

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[00111] Another option is (the use of a default beamfonning vector for the desired user when the PMIJND is 1 (a negative confirmation message) and use a 3-bit PMI to indicate seven possible interfering vectors similar to the case when PMIJND = 0.

[00112] Similarly, for a four user MU-MIMO and rank 1 per user, a schem e is described in table 14.

<td> PMIJND (1 bit)</td><td colspan="2"> PMI (6 bits)</td>

<td> 0</td><td> 000000-100010</td><td> 35 combinations Ci, Cj, Ck, fori, j, k = 1,2,..,8, i&lt; j&lt;k and Ci, Cj, Ck Cdeeired</td>

<td></td><td> loooii - ium</td><td> reserved</td>

<td> 1</td><td> 000 - 111 (First 3 bits indicate the</td><td> Ci, i = 1,2...8</td>

<td></td><td> desired beannfonmng vector)</td><td></td>

<td></td><td> 000-111 (Last 3 bits indicate the interference vector combinations)</td><td> 8 combinations (Ci,Q,Ck), for i, j, k = 1,2 8, i&lt;j&lt;k and Ci, Cj Ck Ψ Cdeaired</td>

Table 14: Separate Coding for Confirmation and Indication Messages

[00113] If some kind of restriction is imposed, the number of vector combinations can be reduced and thus the number of bits can be reduced. For example, if the rule indicates that only certain combinations are allowed, for instance Cl, C2, C3, C4 can be combined together as a group, and C5, C6, C7, C8 can be combined together as a group. But the group Cl, C2, C3, C4 cannot be

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C2, C3, or C4 but cannot be combined with C5, C6, C7, or C8. Combination restriction requirements may be rules to meet unitary properties or a unitary beamforming requirement.

[00114] As an example, assume that Cl is the beamforming vector for the desired user and that the restriction rule is used. The vector combinations can be reduced to seven combinations. For two users, only combinations [Cl, C2], [Cl,

C3], and [Cl, C4] are allowed. For three users only [Cl, C2, C3J, [Cl, C2, C4], and [Cl, C3, C4] are allowed. For four users only [Cl, C2, C3, C4] is allowed.

Table 15 summarizes this particular scheme with restrictions:

<td> Two WTRUs</td><td> S1=(C1, CB), S2=(C1, C3), S3=(C1, C4)</td>

<td> Three WTRUs</td><td> S4=(C1, CB, C3), S5=(C1, C2, C4), S6=(C1, C3, C4)</td>

<td> Four WTRUs</td><td> S7=(C1, CB, C3, C4)</td>

Table 15: Beamforming Vector Combinations (Assuming Cl is the Desired Vector)

[ΟΟ1ΊΒ] Similar tables cam be BinlFfOTdifferent Feamforming vectors other than Cl used for the desired' user. The PMI confirmation and indication messages can be jointly coded: and . the corresponding PMI confirmation and indication scheme can be the following. If PMI_IND = 000, confirm the WTRU*3 feedback. If PMI_IND=001, inform the WTRU that C2 is the interfering beamforming vector. If PMIJIND^OIO, inform the WTRU that C3 is the interfering beamforming vector, and so on as shown in Table 16. If PMI_INI>=111, inform the WTRU that C2, C3, and C4 are the interfering beamforming vectors.

<td> PMIJND (Confirmation/Indication Messages)</td><td> Messages or States</td>

<td> 000</td><td> Confirm</td>

<td> 001</td><td> C2</td>

<td> 010</td><td> C3</td>

<td> 01Ϊ</td><td> C4</td>

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<td> 100</td><td> C2,C3</td>

<td> 101</td><td> C2,C4</td>

<td> 110</td><td> C3, C4</td>

<td> 111</td><td> C2, C3, C4</td>

Table 16: Joint Coding for Precoding Confirmation and Indication Messages

[00116] . Another alternative is to have PMXJND=000 as the confirmation message and PMI_INI>=001-lll as the indication messages to indicate the seven possible desired vectors. The:seven vectors or matrices are selected or preselected from C1-C8. Similar, tables can be built for different beamforming vectors other than Cl for a desired user.

[00117] Joint coding may be performed for the precoding confirmation message, the precoding information, or the indication messages, which may or may not include rank information. In addition, joint coding may also be performed for the rank overrideonessages, the feedback error messages, or other ΜΙΜΟ related information and; messages.

____[00118]-Eigurel-l-showsa-wirelesa-commuiiication-system-with-multipliB eNodeBs 1113 implementing the embodiments as described. Each eNodeB 1113 provides communication coverage for a particular geographic area commonly referred to as cells and shown as idealized hexagons. The term cell can refers to its coverage area depending on the context in which the term is used. To improve system capacity, an eNodeB coverage area may be partitioned into multiple smaller areas, e.g., three smaller areas. WTRUs 1111 may be dispersed throughout the coverage area.

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[00119] EMBODIMENTS

I

1. A method for reducing signaling overhead for a Wireless Transmit/Receive Unit (WTRU), in a multiple-input multiple-output ΜΙΜΟ wireless communications by using precoding confirmation and precoding information or indication in the form of a validation message, the method comprising:

using the validation message to indicate the kind of precoding information used at an evolved Node B (eNodeB) wherein the validation message comprises of ί

at least one bit;

the validation message. provides precoding confirmation message and indication message and validation message could be composed of one confirmation message and one indication message using separate coding;

validation message could also be a single message that indicates confirmation, information, override or error message using joint coding; and indication message can he a precoding information indication message or rank override message or a feedback error message or a combination and can ___indicate precoding informationjfor_single-user SU-MIMQ-and-caii.also-indicafca--desired precoding information,' interfering precoding information or both for multi user MU-MEMO.

2. The method of embodiment 1, wherein the precoding information may also contain precoding matrices or ranks or other precoding related information or a combination of all.

3. The method of embodiment 1, wherein the validation message comprises of at least two of a confirmation message and an indication message, a feedback error message and am override error message. ;

4. The method of embodiment 1, wherein the precoding confirmation and indication messages (validation message) can be separately encoded ar jointly encoded.

i

5. The method of embodiment 1, wherein when the validation message I is separately coded or encoded, the validation message itself consists of two parts: . j a confirmation part and an indication part. i

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6. The method of embodiment 5, wherein the confirmation part uses one bit or a plurality of bitsto cany a positive confirmation message or a negative confirmation message.

7. The method of embodiment 6, wherein a positive confirmation message is used to inform the WTRU that precoding information used at eNodeB is exactly the same as the preceding information fed back from the WTRU.

8. The method of embodiment 6, wherein a negative confirmation message is used to inform WTRU that the precoding information used at the eNodeB is not the same as the precoding information fed back from the WTRU.

9. The method of embodiment 6, wherein the indication part uses at least one hit to carry a two or more indication messages.

10. The method of embodiment 6, wherein the indication part indicates to the WTRU that different precoding information is being used at the eNodeB.

11. The method of embodiment 3, wherein when the validation message is jointly coded or encoded, the validation message combines the confirmation part and the indication part.

__;_12. A_methnd_for_xadncing—signaling—overhead fort_a—Wireless-Transmit/Receive Unit (WTRU), in a multiple-input multiple-output ΜΙΜΟ wireless communications by using precoding confirmation and precoding information or indication, the method comprising:

transmitting a precoding matrix index (PMI) that includes antenna weights and beamforming weights to an evolved Node-B (eNodeB); and receiving a validation message from the eNodeB as a PMI indicator that includes information about its antenna weights.

13. The method of embodiment 12 wherein the part of validation message is sent to the WTRU ria a dedicated reference signal and the part of validation message is sent to the WTRU via control signaling scheme.

14. The method of embodiment 12 wherein the eNodeB sends only a precoding confirmation message or PMI indicator when the PMI of the WTRU and-a PMI of the eNodeB are identical

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WTRU a PMI indicator with its PMI when the PMI of the WTRU and a PMI of the eNodeB are not identical on when the PMI ofthe WTRU is overridden by the PMI of the eNodeB or when a feedback error occurs.

16. The method of embodiment 12 wherein PMI indicator size is one bit or more than one bit, can represent state confirmations and can be any arbitrary value depending upon design choice.

17. A method for reducing signaling overhead for a Wirelers TransmitZReceive Unit (WTRU), in a multiple-input multiple-output ΜΙΜΟ wireless communications, by musing precoding confirmation and precoding information or indication, the method comprising;

transmitting a plurality of precoding matrix indices (PMI) that includes antenna weights and beamforming weights to an eNodeB;

receiving a validation message from the eNode B as an individual PMI indicator for each PMI that includes information about its antenna weights.

18. The method of embodiment 12 wherein the part of validation ._ffiesaagfi_is_sentJtQ_theWTRU-xia-a-dedicated-reference-8ignal-and-the-part-ef---validation message is sent to the WTRU via control signaling scheme.

19. The method of embodiment 17 wherein the eNodeB sends only a PMI indicator when the PMI 'of the WTRU and a PMI of the eNodeB ar® identical.

20. The method of embodiment 17 wherein the Node-B sends to the WTRU a PMI indicator with its PMI when at least one of the PMIs of the WTRU and at least one of the PMIs of the eNodeB are not identical or when the PMI of the WTRU is overridden by the PMI of the eNodeB or when a feedback error occurs.

21. The method of embodiment 17, wherein PMI indicator size is one hilt or more than one bit, can represent state confirmations and can be any arbitrary value depending upon design choice.

22. A method for reducing signaling overhead for a Wireless TransmitZReceive Unit (WTRU), in a multiple-input multiple-output ΜΙΜΟ

-.

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transmitting a plurality of precoding matrix indexes PMI that are separated into groups that includes antenna weights and beamforming weights to a eNodeB;

receiving from the eNodeB a validation message as an individual PMI indicator for each group of PMIb that includes information about its antenna weights.

23. The method of embodiment 22 wherein the part of validation message is sent to the WTRU via a dedicated reference signal and the part of validation message is sent to the WTRU via control signaling scheme.

24. The method of embodiment 22 wherein the eNodeB sends only a PMI indicator that includes the PMI indicators of all groups when the PMIs at the WTRU and a PMI of the group at eNodeB are identical.

26. The method of embodiment 22 wherein the eNodeB sends to the WTRU a PMI indicator with its PMI when at least one ofthe PMIs of groups of theAVTRU-andatleasLoneOfthe.EMIsofthegroupsuteNodeBarenot-identic£lor when the PMI of the WTRU is overridden by the PMI of the eNodeB or when a feedback error occurs.

26. The method of embodiment 22 wherein each group of PMI indicators or each PMI indicator has one bit or more than one bit to indicate whether antenna weights are same for eNodeB and WTRU.

27. The method of embodiment 22 when each group has only one PMI.

28. A method of either of embodiments 1,12,17, or 22 to send the PMI indicator without modifying the existing control signaling wherein the PMI is either attached to or embedded into existing control signaling.

29. A method for reducing signaling overhead in multiple-input multiple-output ΜΙΜΟ wireless'communications by use of a validation message that includes precoding confirmation and precoding information or indication ,messages, and the validation message comprises of::

a confirmation message having one bit;

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one possible sub-message for an indication message having at least one bit showing the different possible precoding information;

one possible sub-message for an override message having at least one bit showing the different override rules for precoding; and one possible sub-message for feedback error message having at least one bit showing different precoding rules to handle feedback error.

30. An evolved Node R eNodeB for reducing signaling overhead between a Wireless Transmit/Receive Unit (WTRU) and the eNodeB, in a multiple-input multiple-output ΜΙΜΟ wirelessicommunications by using precoding confirmation and precoding information or indication in the form of a validation message, the eNodeB configured to:

transmit the validation message to indicate the kind of precoding information used at the eNodeB wherein the validation message comprises of g t least one bit;

the validation message provides confirmation message and indication message and-validationjuessaggcouldbe-compoaedofoneconfirmationmessage------and one indication message using separate coding;

validation message could also he a single message that indicates confirmation, information, override or error message using joint coding; and indication message can be a precoding information indication message or rank override message or a feedback error message or a combination and can indicate precoding informationfor single user SU-MEMO and can also indicate desired precoding information,: interfering precoding information or both for multi user MU-MEMO.

31. The eNode of embodiment 30, wherein the precoding information may contain precoding matrices or ranks or other precoding related information or a combination of all.

32. The eNodeB of embodiment 30, wherein the validation message comprises a combination of at least two of a confirmation message, an indication message, a feedback error message and an override error message.

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33. The eNodeB of embodiment 30, wherein the validation message can be separately coded or encoded or jointly coded or encoded.

34. The eNodeB of embodiment 30, wherein when the precoding confirmation and indication messages (validation message) is separately coded or encoded, the validation message itself consists of two parts: a confirmation pai-t and an indication part.

35. The eNodeB of embodiment 34, wherein the confirmation part uses one hit or more than one bit ; to carry a positive-confirmation message or a negative confirmation message.

36. The eNodeB of embodiment 34, wherein a positive confirmation message is used to inform tbe WTRU that precoding information used at eNodeB is exactly the same as the precoding information fed back from the WTRU.

37. The eNodeB of embodiment 34, wherein a negative confirmation message is used to inform WTRU that the precoding information used at the eNodeB is not the same as the precoding information fed back from the W'iRU.

38. The eNodeB of embodiment 34, wherein the indication part uses at ^:_least one bit to carrv a two ormoreJndication messages_______

39. The eNodeB of embodiment 34, wherein the indication part indicates to the WTRU that different precoding information is being used at the eNodeB,

40. The eNodeB of embodiment 34, wherein when the validation message is jointly coded or encoded, the validation message combines the confirmation part and the indication part into a single part or field.

41. An evolved Node :B (eNodeB) for reducing signaling overhead, operating in multiple-input multiple-output MEMO wireless communications suitable for precoding confirmation and precoding information or indication and configured to:

receive a precoding matrix index (PMI) from a Wireless Transmit/Receivo Unit (WTRU) that includes the:WTRUs antenna weights;

transmit a validation message to the WTRU as a PMI indicator thac includes information about its own antenna weights.

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42. The eNodeB of embodiment 41 wherein the validation message is sent to the WTRU via a dedicated reference signal or via control signaling scheme.

43. The eNodeB of embodiment 41 wherein the eNodeB sends only a PMI indicator when the PMI of the WTRU and a PMI of the eNodeB are identical.

44. The eNodeB of embodiment 41 wherein the Node-B sends to the WTRU a PMI indicator with its PMI when the PMI of the WTRU and a PMI of the eNodeB are not identical oriwhen the PMI of the WTRU is overridden by the PMI of the eNodeB or when a feedback error occurs.

45. The eNodeB of embodiment 41 wherein PMI indicator size is one hit or more than one bit, can represent state confirmations and can be any arbitrary value depending upon design choice.

46. An evolved Node¹ B (eNodeB) for reducing signaling overhead, operating in multiple-input multiple-output MEMO wireless com mi mirations suitable for precoding confirmation and precoding information or indication and configured to:........:-----~---------------receive a plurality of precoding matrix indices (PMIs) from a Wireless Transmit/Receive Unit (WTRU) that includes the WTRUs antenna weights; and transmit a validation message to the WTRU as an individual PMI indicator that includes information about its own antenna weights.

47. The method of embodiment 46 wherein the part of validation message is sent to the WTRU via a dedicated reference signal and the part of validation message is sent to the WTRU via control signaling scheme.

48. The eNodeB of embodiment 46 wherein the eNodeB sends only a PMI indicator when the PMI of the WTRU and a PMI of the eNodeB are identical.

49. The eNodeB of embodiment 46 wherein the eNodeB sends to the WTRU a PMI indicator with itsPMI when at least one of the PMIb of the WTRU and at least one of the PMIs of the eNodeB are not identical or when the PMI of

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50. The eNodeB of embodiment 46 wherein PMI indicator size is one bit or more than one bit, can represent state confirmations and can be any arbitrary value depending upon design choice.

51. The eNodeB of embodiment 46 configured to send the PMI indicator without modifying the existing control signaling wherein the PMI is either attached to or embedded into existing control signaling.

52. An evolved Node- B (eNodeB) for reducing signaling overhead, operating in multiple-input multiple-output ΜΙΜΟ wireless communications suitable for precoding confirmation and precoding information or indication and configured to:

receive a plurality of precoding matrix indices (PMIs) from a Wireless Transmit/Receive Unit (WTRU) that are separated into groups that includes the WTRUs antenna weights; and transmit a validation message to the WTRU as an individual PMI ______indicatQr_for_each_group-of-RMIs—that-includes-mformation-about4ts-ow5a-. antenna weights.

53. The eNodeB of embodiment 52, wherein part of validation message is sent to the WTRU via a dedicated reference signal and the part of validation message is sent to the WTRU via control signaling scheme.

54. The eNodeB of embodiment 52, wherein the eNodeB sends only a PMI indicator that includes the PMI indicators of all groups when the PMIs at the WTRU and a PMI of the group at eNodeB are identical.

55. The eNodeB of embodiment 52 wherein the eNodeB sends to the WTRU a PMI indicator with itsi PMI when at least one of the PMIs of groups of the WTRU and at least one of thb PMIs of the groups at eNodeB are not identical or when the PMI ofthe WTRU is overridden by the PMI of the eNodeB or when a feedback error occurs.

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56. The eNodeB of embodiment 52 wherein each group of PMI ¹ indicators or each PMI indicator has one bit or more than one hit to indicate whether antenna weights are same for eNodeB and WTRU.

57. The eNodeB of embodiment 52 wherein each group has only one

PMI.

58. The eNodeB of embodiment 52 configured to send the PMI indicator without modifying the existing control signaling wherein the PMI is either ¹ attached to or embedded into existing control signaling.

59. An evolved Nodes B (eNodeB) for reducing signaling overhead, operating in multiple-input miiltiple-output ΜΙΜΟ wireless communications i having a transceiver and processor for precoding confirmation and precoding information, or indication and configured to generate a validation message that includes precoding matrix information PMI, and the validation message comprises: ’ a confirmation message having one bit; or a confirmation message having more than one bit;

___ one possible sub-messagd for anindicatjon mesaage having at leaat one hit------showing the different possible precoding information;

one possible sub-message for an override message having at least one hit showing the different override rules for precoding; and one possible sub-message for feedback error message having at least one bit showing different precodingirules to handle feedback error.

60. A wireless transmit/receive unit (WTRU) for reducing signaling j overhead between an evolved-Node B and the WTRU, in a multiple-input multiple-output ΜΙΜΟ wireless>communicationB by using precoding confirmation and precoding information or indication in the form of a validation message, the ¹

WTRU configured to : j receive the validation message to indicate the kind of precoding information used at the eNodeB’wherein the validation message comprises of at least one bit;

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ITC-2-1683.01.WO REPLACEMENT SHEET . I the validation message provides precoding confirmation message and indication message and validation message could be composed of one confirmation message and oneiindication message using separate coding;

validation message could also be a single message that indicates confirmation, information, override or error message using joint coding; and indication message can he a precoding information indication message or rank override message or a feedback error message or a combination and can indicate precoding information) for single user SU-MIMO and can also indicate desired precoding information; interfering precoding information or both f6r multi user MU-MIMO.

61. The WTRU of embodiment 60, wherein the validation message comprises a combination of at least two of: a confirmation message, an indication message, a feedback error message and an override error message.

62. The WTRU of embodiment 60, wherein the precoding information and indication messages (validation message) can be separately encoded or jointly encoded.

_63, The WrfeU of embt^dimentfiP, jgheranwhentii&amp;validatiQn-mesBflgBis separately coded or encoded, the validation message itself consists of two parts: a confirmation part and an indication part.

64. The WTRU of embodiment 63, wherein the confirmation part uses one hit or more than one bit to carry a positive-confirmation message or a negative confirmation message.

65. The WTRU of embodiment 60, wherein a positive confirmation message is used to inform the WTRU that precoding information used at eNodeB is exactly the same as the preceding information fed back from the WTRU.

66. The WTRU of embodiment 60, wherein a negative confirmation message is used to inform WTRU that the precoding information used at the eNodeB is not the same as the precoding information fed hack from the WTRU.

67. The WTRU of embodiment 63, wherein the indication part uses one bit or more than one bit to carry a two or more indication messages.

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68. The WTRU of embodiment 64, wherein the indication part indicates to the WTRU that different preceding information is being used at the eNodeB.

69. The WTRU of embodiment 64, wherein when the validation message is jointly coded or encoded* the validation message combines the confirmation part and the indication part.

70. . A wireless transmit/receive unit WTRU for reducing signaling overhead, operating in multiple-input multiple-output ΜΙΜΟ wireless communications having a transceiver and processor and processor for precoding confirmation and precoding information or indication and configured to general» a validation message that includes precoding matrix information PMI, and the validation message comprises:

a confirmation message having one bit; or a confirmation message having at least one bit;

one possible sub-message for an indication message having at least one bit showing the different possible precoding information;

one possible sub-message for an override message having at least one bit __\__showing the different override ruleB for precoding:_and_________________ one possible sub-message for feedback error message having at least one bit showing different precoding rules to handle feedback error.

71. A wireless transmit/receive unit (WTRU) for reducing signaling overhead, operating in multiple-input multiple-output ΜΙΜΟ wireless communications, having a transceiver and a processor for precoding confirmation and precoding information or indication and configured to:

transmit a precoding matrix index (PMI) to an evolved Node B (eNodeB) that includes the WTRUs antenna weights;

receive a validation mes(3age from the eNodeB as a PMI indicator that includes information about its cwn antenna weights.

72. The WTRU of embodiment 71, wherein part of validation message is received via a dedicated reference signal and the part of validation message i.3 received via control signaling scheme.

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73. The WTRU of embodiment 72, wherein the WTRU receives only a precoding confirmation or PMI indicator when the PMI of the WTRU and PMI of the eNodeB are identical.

74. The WTRU of embodiment 71, wherein the WTRU receives a PMI indicator with its PMI when the PMI of the WTRU and a PMI of the eNodeB afe not identical or when the PMS of the WTRU is overridden by the PMI of th e eNodeB or when a feedback error occurs.

75. The WTRU of embodiment 71, wherein PMI indicator size is one bit ' or more than one bit, can represent state confirmations and can be any arbitrary value depending upon design choice.

76. The WTRU of embodiment 71, wherein part of validation message is received by the transceiver via a dedicated reference signal and the part of validation message is received via control signaling scheme.

77. A wireless transmit/receive unit (WTRU) for reducing signaling overhead, operating in multiple-input multiple-output ΜΙΜΟ wireless communications, having a transceiver and a processor for precoding confirmation __ and precodinginformation.or.mciicationandconfigured4o:--------transmit a plurality of precoding matrix indices (PMIs) to an evolved Node

B (eNodeB) that includes the WTRUS antenna weights; and receive a validation message from the eNodeB as an individual PMI indicator that includes information about eNodeBs own antenna weights.

78. The WTRU of embodiment 77, wherein part of validation message is received by the transceiver via a dedicated reference signal or via control signaling scheme.

79. The WTRU of embodiment 77, wherein the WTRU receives only a PMI indicator from the eNodeE when the PMI of the WTRU and a PMI of the eNodeB are identical.

80. The WTRU of embodiment 77, wherein the WTRU receives a PMI indicator with eNodeBs PMI when at least one of the PMIs of the WTRU and at least one of the PMIs of the eNodeB are not identical or when the PMI of the WTRU is overridden by the ΡΜΪ of the eNodeB or when a feedback error occurs.

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81. The WTRU of embodiment 80, wherein PMI indicator size is one bit or more than one bit, can represent state confirmations and can be any arbitrary value depending upon design choice.

82. A wireless transmit/receive unit (WTRU) for reducing signaling overhead, operating in multiple-input multiple-output ΜΙΜΟ wireless communications, having a transceiver and a processor for precoding matrix indication and configured to:

transmit a plurality of precoding matrix indices (PMIs) to an evolved Node B (eNodeB) that are separated., into groups that includes the WTRUs antenna weights; and receive a validation message from the eNodeB as an individual PMI indicator for each group of PMIs that includes information about its own antenna weights.

83. The WTRU of embodiment 82, wherein part of validation message is received by the transceiver via a dedicated reference signal and the part cf validation message is received via control signaling scheme.

__84. The WTRU of embodiment 82, wherein the wherein, the WTRU___ receives only a PMI indicator from the eNodeB that includes the PMI indicators of all groups when the PMIs at the WTRU and a PMI of the group at eNodeB are identical

85. The WTRU of embodiment 82, wherein the WTRU receives a ΡΜΪ indicator from eNodeB with its PMI when at least one of the PMIs of groups cf the WTRU and at least one of the PMIs of the groups at eNodeB are not identical or when the PMI of the WTRU is overri dden by the PMI of the eNodeB or when a feedback error occurs.

86. The WTRU of embodiment 82, wherein each group of PMI indicators or each PMI indicator has on.» bit or more than one bit to indicate whether antenna weights are same for eNodeB and WTRU.

87. The WTRU of embodiment 82, wherein each group has only one

PMI.

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I

88. The WTRU of embodiment 82 configured to receive the PMI indicator from the eNodeB wherein the PMI is either attached to or embedded into existing control signaling.

. [00120] Although the features and elements of the present invention are . described in the preferred embodiments in particular combinations, each feature or element can be used alone without the other features and elements of th e ' preferred embodiments or in various combinations with or without other features and elements of the present invention. The methods or flow charts provided in : the present invention may be implemented in a computer program, software, or ( firmware tangibly embodied iin a computer-readable storage medium for execution by a general purpose computer or a processor. Examples of computerreadable storage mediums include a read only memory ROM, a random access memory RAM, a register, cache memory, semiconductor memory devices, !

magnetic media such as internal hard disks and removable disks, magnetooptical media, and optical media such as CD-ROM disks, and digital versatile disks DVDs.

_____[00121] Suitable processor include.Javjvav.of-example.-a general DurpGga-----1 processor, a special purpose processor, a conventional processor, a digital signal processor DSP, a plurality of microprocessors, one or more microprocessors in association with a DSP core, a controller, a microcontroller, Application Specific Integrated Circuits ASICs, Field Programmable Gate Arrays FPGAs circuits, any other type of integrated circuit XC, and/or a state machine.

[00122] A processor in association, with software may be used to implement { a radio frequency transceiver for use in a wireless transmit receive unit WTRU,

Wireless Transmit/Receive Unit WTRU, terminal, base station, radio network controller RNC, or any host computer. The WTRU may be used in conjunction ' with modules, implemented in hardware and/or software, such as a camera, a I video camera module, a videophone, a speakerphone, a vibration device, a speaker, a microphone, a television transceiver, a hands free headset, a keyboard, a Bluetooth® module, a frequency modulated FM radio unit, a liquid crystal display LCD display unit, an organic light-emitting diode OLED display unit, a !

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