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), a codebook value representing a multi-column precoding matrix, as feedback;
receiving, by the WTRU via the eNB, control signaling including a multi-bit indicator;
determining, by the WTRU based on the multi-bit indicator, a rank and precoding information for decoding by the WTRU; and
decoding, by the WTRU, the data received via the eNB using the determined precoding information,
wherein:
on condition that the multi-bit indicator corresponds to a first value, the rank is one and the precoding information is based on a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback,
on condition that the multi-bit indicator corresponds to a second value, the rank is one and the precoding information is based on the second column of the multi-column precoding matrix represented by the codebook value sent in the feedback, and
on condition that the multi-bit indicator corresponds to a third value, the rank is greater than one and the precoding information is based on a predetermined precoding matrix that is not sent in the feedback.
2. The method of claim 1 , further comprising on condition that the multi-bit indicator corresponds to a fourth value, the rank is greater than one and the precoding information is based on a plurality of columns of the multi-column precoding matrix represented by the codebook value sent in the feedback, wherein the decoding of the received data uses the precoding information determined based on the plurality of columns of the multi-column precoding matrix represented by the codebook value sent in the feedback.
3. 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.
4. The method of claim 1 , wherein:
the sending of the feedback includes sending a suggested rank for communications with the eNB; and
on condition that the multi-bit indicator corresponds to the first value or the second value, determining, by the WTRU, that the eNB has overridden the suggested rank from the WTRU for communication with the eNB.
5. A Wireless Transmit/Receive Unit (WTRU) configured to decode received data, comprising:
a transmitter/receiver unit configured to:
send, to an evolved Node B (eNB), a codebook value representing a multi-column precoding matrix, as feedback, and
receive, via the eNB, control signaling including a multi-bit indicator; and
a processor configured to:
determine, by the WTRU based on the multi-bit indicator, a rank and precoding information associated with the WTRU, and
decode the data received via the eNB using the determined precoding information,
wherein:
on condition that the multi-bit indicator corresponds to a first value, the rank is one and the precoding information is based on a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback,
on condition that the multi-bit indicator corresponds to a second value, the rank is one and the precoding information is based on a second column of the multi-column precoding matrix represented by the codebook value sent in the feedback, and
on condition that the multi-bit indicator corresponds to a third value, the rank is greater than one and the precoding information is based on a predetermined precoding matrix that is not sent in the feedback.
6. The WTRU of claim 5 , wherein on condition that the multi-bit indicator corresponds to a fourth value, the rank is greater than one and the precoding information is based on a plurality of columns of the multi-column precoding matrix represented by the codebook value sent in the feedback.
7. The WTRU of claim 5 , wherein the processor is configured to translate the codebook value sent in the feedback to the precoding information to decode the received data.
8. The WTRU of claim 1 , wherein:
the transmitter/receiver unit configured to sending a suggested rank for communication with the eNB; and
the processor is configured to, on condition that the multi-bit indicator corresponds to the first value or the second value, determine that the eNB has overridden the suggested rank from the WTRU for communication with the eNB.
9. A network entity configured to signal control information, comprising:
a transmitter/receiver unit configured to receive, from a wireless transmit/receive unit (WTRU), a codebook value representing a multi-column precoding matrix and a suggested rank of greater than one, as feedback; and
a processor configured to:
determine whether to assign the suggested rank of greater than one, which was suggested by the WTRU in the feedback, or a rank of one for communication with the WTRU, and
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, the assigned rank is one and precoding information is based on a first column of the multi-column precoding matrix represented by the codebook value sent in the feedback; (2) on condition that the multi-bit indicator corresponds to a second value, the assigned rank is one and the precoding information is based on a second column of the multi-column precoding matrix represented by the codebook value sent in the feedback; (3) on condition that the multi-bit indicator corresponds to a third value, the assigned rank is greater than one and the precoding information is based on a predetermined precoding matrix that is not sent in the feedback,
wherein the transmitter/receiver unit is configured to send, to the WTRU, the generated control signaling including the multi-bit indicator.
10. The network entity of claim 9 , wherein on condition that the multi-bit indicator corresponds to a fourth value, indicating to the WTRU the rank is greater than one and the precoding information is based on a plurality of columns of the multi-column precoding matrix represented by the codebook value sent in the feedback.
11. The network entity of claim 9 , wherein the transmitter/receiver unit is configured to send to the WTRU data coded in accordance with the precoding information.