Method and apparatus for efficient precoding information validation for MIMO communications
A method and apparatus for efficient precoding matrix verification in a multiple-input multiple-output MIMO wireless communication system are disclosed. A wireless transmit/receive unit WTRU sends a precoding matrix index PMI to an eNodeB. The eNodeB sends a verification message including a PMI indicator indicating whether or not the PMI of the WTRU and a PMI of the eNodeB are identical. If the PMI of the WTRU and of the eNodeB are identical, the eNodeB sends just a PMI indicator otherwise the eNodeB sends to the WTRU a PMI indicator and the PMI of the eNodeB. A plurality of PMIs may be sent simultaneously, and the PMIs may be partitioned into a plurality of groups. The PMI indicator may be either attached to or inserted into control signaling. PMI validation messages can be signaled to WTRU by control signaling or use of a dedicated reference signal.
1. A method of decoding data received by a Wireless Transmit/Receive Unit (WTRU), the method comprising:
sending, by the WTRU to an evolved Node B (eNB), (1) a rank indicator indicating a rank of greater than one, the rank of greater than one being suggested by the WTRU for communication with the WTRU and (2) a codebook value representing a multi-column precoding matrix, as feedback;
receiving, by the WTRU, control signaling including a multi-bit indicator;
on condition that the multi-bit indicator corresponds to a first value which indicates to use the rank and the multi-column precoding matrix represented by the codebook value associated with the feedback, determining, by the WTRU, precoding information based on the multi-column precoding matrix represented by the codebook value sent in the feedback to decode the data;
on condition that the multi-bit indicator corresponds to a second value which indicates to use a rank of one and a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback, determining, by the WTRU, the precoding information based on the first column of the multi-column precoding matrix represented by the codebook value sent in the feedback to decode the data;
on condition that the multi-bit indicator corresponds to a third value which indicates to use the rank of one and a second column of the multi-column precoding matrix represented by the codebook value sent in the feedback, determining, by the WTRU, the precoding information based on the second column of the multi-column precoding matrix represented by the codebook value sent in the feedback to decode the data; and
decoding, by the WTRU, the received data using the determined precoding information.
2. The method of claim 1 , further comprising translating the codebook value sent in the feedback to the precoding information for decoding of the received data.
3. A Wireless Transmit/Receive Unit (WTRU) configured to decode received data, comprising:
a processor and transmitter/receiver unit configured to:
send to an evolved Node B (eNB), (1) a rank indicator indicating a rank of greater than one, the rank of greater than one being suggested by the WTRU for communication with the WTRU and (2) a codebook value representing a multi-column precoding matrix, as feedback;
receive control signaling including a multi-bit indicator;
on condition that the multi-bit indicator corresponds to a first value which indicate to use the rank and multi-column precoding matrix represented by the codebook value associated with the feedback, determine precoding information based on the multi-column precoding matrix represented by the codebook value sent in the feedback to decode the data;
on condition that the multi-bit indicator corresponds to a second value which indicates to use a rank of one and a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback, determine the precoding information based on the first column of the multi-column precoding matrix represented by the codebook value sent in the feedback to decode the data;
on condition that the multi-bit indicator corresponds to a third value which indicates to use the rank of one and a second column of the multi-column precoding matrix represented by the codebook value sent in the feedback, determine precoding information based on the second column of the multi-column precoding matrix represented by the codebook value sent in the feedback to decode the data; and
decode the received data using the determined precoding information.
4. The WTRU of claim 3 , wherein the processor is configured to translate the codebook value sent in the feedback to the precoding information to decode the received data.
5. A network entity configured to signal control information, comprising:
a processor and transmitter/receiver unit configured to:
receive, from a wireless transmit/receive unit (WTRU), (1) a rank indicator indicating a rank of greater than one, the rank of greater than one being suggested by the WTRU for communication with the WTRU and (2) a codebook value representing a multi-column precoding matrix, as feedback;
determine whether to assign a rank of one for communication with the WTRU;
generate control signaling including a multi-bit indicator that indicates to the WTRU: (1) on condition that the multi-bit indicator corresponds to a first value, to use the rank and multi-column precoding matrix represented by the codebook value associated with the feedback for decoding data; (2) on condition that the multi-bit indicator corresponds to a second value, to the use a rank of one and a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback for the decoding of the data; and (3) on condition that the multi-bit indicator corresponds to a third value, to use the rank of one and a second column of the multi-column precoding matrix represented by the codebook value sent in the feedback for the decoding of the data; and
send, to the WTRU, the generated control signaling including the multi-bit indicator.
6. The network entity of claim 5 , wherein the processor is configured to translate the codebook value sent in the feedback to precoding information.
7. A method implemented by a network entity, comprising:
receiving, by the network entity from a wireless transmit/receive unit (WTRU), (1) a rank indicator indicating a rank of greater than one, the rank of greater than one being suggested by the WTRU for communication with the WTRU and (2) a codebook value representing a multi-column precoding matrix, as feedback;
determining, by the network entity, whether to assign a rank of one for communication with the WTRU;
generating, by the network entity, control signaling including a multi-bit indicator that indicates to the WTRU: (1) on condition that the multi-bit indicator corresponds to a first value, to use the rank and multi-column precoding matrix represented by the codebook value associated with the feedback for decoding data; (2) on condition that the multi-bit indicator corresponds to a second value, to the use a rank of one and a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback for the decoding of the data; and (3) on condition that the multi-bit indicator corresponds to a third value, to use the rank of one and a second column of the multi-column precoding matrix represented by the codebook value sent in the feedback for the decoding of the data; and
sending, by the network entity to the WTRU, the generated control signaling including the multi-bit indicator.
8. The method of claim 7 , further comprising translating the codebook value sent in the feedback to precoding information.