Method and apparatus for feedback overhead reduction in wireless communications
A method and apparatus for reducing feedback transmission overhead in wireless communications. Averaging, compression, or both are used to reduce a number of bits needed for transmission of channel quality information.
1. A wireless transmit/receive unit (WTRU) comprising:
a processor configured to determine a first channel quality metric for a first transmission layer of each of N groups of sub-bands of a downlink bandwidth and a second channel quality metric for a second transmission layer of each of the N groups of sub-bands of the downlink bandwidth, wherein N is a positive integer greater than 1 and each group comprises a plurality of sub-bands of the downlink bandwidth; and
wherein the processor is configured to transmit each of the N pairs of first and second channel quality metrics in a different reporting transmission time interval (TTI).
2. The WTRU of claim 1 wherein the reporting TTI and the sub-band group to be reported in that reporting TTI are known in advance of the transmission by the WTRU and a wireless network.
3. The WTRU of claim 1 wherein the transmission in each of the reporting transmission time intervals does not include an index of a position of the group within the downlink bandwidth.
4. A method comprising:
determining, by a wireless transmit/receive unit (WTRU), a first channel quality metric for a first transmission layer of each of N groups of sub-bands of a downlink bandwidth and a second channel quality metric for a second transmission layer of each of the N groups of sub-bands of the downlink bandwidth, wherein N is a positive integer greater than 1 and each group comprises a plurality of sub-bands of the downlink bandwidth; and
transmitting, by the WTRU, each of the N pairs of first and second channel quality metrics in a different reporting transmission time interval (TTI).
5. The method of claim 4 wherein the reporting TTI and the sub-band group to be reported in that reporting TTI are known in advance of the transmission by the WTRU and a wireless network.
6. The method of claim 4 wherein the transmission in each of the reporting transmission time intervals does not include an index of a position of the group within the downlink bandwidth.
7. A wireless network node comprising:
a processor and a receiver configured to receive first and second channel quality index (CQI) metrics from a wireless transmit/receive unit (WTRU) in N reporting transmission time intervals (TTIs);
wherein the first CQI metric in each of the N reporting TTIs corresponds to a first transmission layer of a respective one of N groups of sub-bands of a downlink bandwidth and the second CQI metric in each of the N reporting TTIs corresponds to a second transmission layer of the respective one of the N groups of sub-bands of the downlink bandwidth.
8. The wireless network device of claim 7 wherein each reporting TTI and the sub-band group to be reported in that reporting TTI are known in advance of reception by the wireless network device.
9. The wireless network device of claim 7 wherein information received in the N reporting TTIs does not include an index of a position of the group within the downlink bandwidth.
10. The wireless network device of claim 7 wherein the processor is further configured to determine a CQI metric for all of the N groups from CQI information in each of the N reporting TTIs.