Feedback Method For Performing A Feedback By Using A Codebook In Mimo System

Abstract

A feedback method for performing a feedback by using a codebook in Multiple Input Multiple Output (MIMO) system includes receiving, by the mobile station, a MIMO mode type information, generating feedback information by using the codebook selected according to the MIMO mode type information, and transmitting the feedback information to the base station. The codebook includes a SU-MIMO codebook and a MU-MIMO codebook, and the MU-MIMO codebook is formed by extracting codebook elements from the SU-MIMO codebook. As a result, the method maximizes a system throughput simultaneously while effectively reducing an amount of feedback information.

1 . A method for receiving, by a base station having N t  (>1) transmit antennas, a feedback from a mobile station, the method comprising:
 transmitting multi-input multi-output (MIMO) mode type information to the mobile station; and   receiving feedback information transmitted according to the MIMO mode type information from the mobile station;   computing a precoding matrix for the mobile station by using the feedback information and a codebook selected according to the MIMO mode type information,   wherein the selected codebook is one of a plurality of single-user MIMO (SU-MIMO) codebooks each of which is defined per rank for N t  transmit antennas or a multi-user MIMO (MU-MIMO) codebook,   wherein the MU-MIMO codebook is formed with codebook elements extracted from an SU-MIMO codebook of rank- 1  for N t  transmit antennas.   
     
     
         2 . The method of  claim 1 , wherein the plurality of SU-MIMO codebooks include the SU-MIMO codebook of rank- 1 , an SU-MIMO codebook of rank- 2 , . . . , an SU-MIMO codebook of rank-N t . 
     
     
         3 . The method of  claim 1 , wherein the MIMO mode type information indicates an SU-MIMO mode or an MU-MIMO mode. 
     
     
         4 . The method of  claim 3 , wherein when the MIMO mode type information indicates the MU-MIMO mode, the selected codebook is the MU-MIMO codebook. 
     
     
         5 . The method of  claim 3 , wherein when the MIMO mode type information indicates the SU-MIMO mode, the selected codebook is the one of the plurality of SU-MIMO codebooks. 
     
     
         6 . The method of  claim 1 , further comprising:
 transmitting, to the mobile station, information indicating which codebook elements of the SU-MIMO codebook of rank-1 are prohibited for the feedback.   
     
     
         7 . A method for transmitting, by a mobile station, a feedback to a base station having N t  (>1) transmit antennas, the method comprising:
 receiving multi-input multi-output (MIMO) mode type information from the base station;   selecting a precoding matrix from a codebook selected according to the MIMO mode type information, and   transmitting feedback information indicating the precoding matrix to the mobile station,   wherein the selected codebook is one of a plurality of single-user MIMO (SU-MIMO) codebooks each of which is defined per rank for N t  transmit antennas or a multi-user MIMO (MU-MIMO) codebook,   wherein the MU-MIMO codebook is formed with codebook elements extracted from an SU-MIMO codebook of rank-1 for N t  transmit antennas.   
     
     
         8 . The method of  claim 7 , wherein the plurality of SU-MIMO codebooks include the SU-MIMO codebook of rank- 1 , an SU-MIMO codebook of rank- 2 , . . . , an SU-MIMO codebook of rank-N t . 
     
     
         9 . The method of  claim 7 , wherein the MIMO mode type information indicates an SU-MIMO mode or an MU-MIMO mode. 
     
     
         10 . The method of  claim 9 , wherein when the MIMO mode type information indicates the MU-MIMO mode, the selected codebook is the MU-MIMO codebook. 
     
     
         11 . The method of  claim 9 , wherein when the MIMO mode type information indicates the SU-MIMO mode, the selected codebook is the one of the plurality of SU-MIMO codebooks. 
     
     
         12 . The method of  claim 7 , further comprising:
 receiving, from the base station, information indicating which codebook elements of the SU-MIMO codebook of rank- 1  are prohibited for the feedback.