Method of transmitting feedback message in wireless communication system
A method of transmitting a feedback message in wireless communication system is provided. The method includes selecting N best subbands of M subbands according to CQI, where both M and N are a natural number and M is larger than N, generating multiple input multiple output (MIMO) information comprising N codebook indexes and N differential CQIs and transmitting the feedback message comprising the MIMO information.
1. A method of transmitting a feedback message through a feedback header, the method comprising:
receiving a feedback request message comprising a feedback type field; and
transmitting a feedback header as a response to the feedback request message,
wherein the feedback header has a format comprising the feedback type field and a feedback contents field, wherein a value of the feedback type field indicates a type of information contained in the feedback contents field, and
wherein when the value of feedback type field indicates a closed-loop (CL) multiple input multiple output (MIMO) feedback, the feedback contents field comprises a CL MIMO type field and MIMO information, the CL MIMO type field indicating any one of an antenna grouping, an antenna selection, a codebook based feedback and transition from CL MIMO to open-loop MIMO, and
wherein when the CL MIMO type indicates the codebook based feedback, the MIMO information comprises N codebook indexes and N differential CQIs, wherein the N codebook indexes indicate codebooks used for N best subbands of M subbands according to channel quality indicator (CQI), where both M and N are natural numbers and M is larger than N, and each of the N differential CQIs indicates difference between a reference CQI and a CQI for each of the N best subbands.
2. The method of claim 1 , wherein the feedback type field comprises 4 bits.
3. The method of claim 1 , wherein the CL MIMO type field comprises 2 bits.
4. The method of claim 1 , wherein the reference CQI is transmitted before the feedback message is transmitted.
5. The method of claim 1 , wherein a bit-size of the feedback contents field is 16 bits or 32 bits.
6. The method of claim 1 , wherein the feedback request message further comprises an uplink radio resource allocation used to transmitting the feedback header.
7. The method of claim 1 , wherein the feedback request message is a feedback polling message transmitted on an uplink (UL)-MAP.
8. A mobile station (MS) comprising:
a radio frequency (RF) unit for transmitting and receiving a radio signal; and
a processor coupled with the RF unit and configured to
receive a feedback request message comprising a feedback type field; and
transmit a feedback header as a response to the feedback request message,
wherein the feedback header has a format comprising the feedback type field and a feedback contents field, wherein a value of the feedback type field indicates a type of information contained in the feedback contents field, and
wherein when the value of feedback type field indicates a closed-loop (CL) multiple input multiple output (MIMO) feedback, the feedback contents field comprises a CL MIMO type field indicating any one of an antenna grouping, an antenna selection, a codebook based feedback and transition from CL MIMO to open-loop MIMO, and
wherein when the CL MIMO type indicates the codebook based feedback, the MIMO information comprises N codebook indexes and N differential CQIs, wherein the N codebook indexes indicate codebooks used for N best subbands of M subbands according to channel quality indicator (CQI), where both M and N are natural numbers and M is larger than N, and each of the N differential CQIs indicates difference between a reference CQI and a CQI for each of the N best subbands.