Precoding and feedback channel information in wireless communication system

Abstract

The present invention relates to precoding and feedback channel information in wireless communication system. A method includes receiving a first Precoding Matrix Index (PMI) and a second PMI from a terminal; mapping one or two codewords into layers; precoding symbols mapped into the layers using a first precoding matrix derived from the first PMI and a second precoding matrix derived from the second PMI; and transmitting the precoded symbols to the terminal, wherein the reception of the first PMI is less frequent than the reception of the second PMI.

1 . A method for transmitting control information of a terminal, the method comprising:
 estimating a downlink channel from a signal received from a base station;   transmitting a first precoding matrix index (PMI) to the base station;   transmitting a second PMI to the base station; and   receiving, from the base station, precoded data symbols through an antenna,   wherein the precoded data symbols are mapped into at least one layers based on a precoding matrix derived from the first PMI and the second PMI.   
     
     
         2 . The method of  claim 1 , wherein the transmission frequencies of the first PMI and the second PMI are different from each other. 
     
     
         3 . The method of  claim 2 , wherein the transmission of the first PMI is more frequent than the transmission of the second PMI. 
     
     
         4 . The method of  claim 2 , wherein the second PMI is transmitted in every several transmissions of the first PMI. 
     
     
         5 . The method of  claim 1 , wherein a rank indicator (RI) is transmitted with at least one of the first PMI and the second PMI. 
     
     
         6 . A mobile terminal, comprising:
 a receiver configured to receive, from the base station, a signal; and   a channel estimator configured to estimate a downlink channel from the received signal;   wherein the mobile terminal is configured to transmit a first precoding matrix index (PMI) and a second PMI to the base station,   wherein the receiver is further configured to receive, from the base station, precoded data symbols through an antenna,   wherein the precoded data symbols are mapped into at least one layers based on a precoding matrix derived from the first PMI and the second PMI.   
     
     
         7 . The mobile terminal of  claim 6 , wherein the transmission frequencies of the first PMI and the second PMI are different from each other. 
     
     
         8 . The mobile terminal of  claim 7 , wherein the transmission of the first PMI is more frequent than the transmission of the second PMI. 
     
     
         9 . The mobile terminal of  claim 7 , wherein the second PMI is transmitted in every several transmissions of the first PMI. 
     
     
         10 . The mobile terminal of  claim 6 , wherein a rank indicator (RI) is transmitted with at least one of the first PMI and the second PMI. 
     
     
         11 . A method for receiving control information by a base station, the method comprising:
 transmitting a signal for channel estimation to a mobile terminal;   receiving a first precoding matrix index (PMI) from the mobile terminal;   receiving a second PMI from the mobile terminal;   precoding symbols based on a precoding matrix derived from the first PMI and the second PMI;   mapping the precoded data symbols into at least one layer; and   transmitting, to the mobile terminal, the precoded data symbols through at least one antenna.   
     
     
         12 . The method of  claim 11 , wherein the transmission frequencies of the first PMI and the second PMI are different from each other. 
     
     
         13 . The method of  claim 12 , wherein the transmission of the first PMI is more frequent than the transmission of the second PMI. 
     
     
         14 . The method of  claim 12 , wherein the second PMI is transmitted in every several transmissions of the first PMI. 
     
     
         15 . The method of  claim 11 , wherein a rank indicator (RI) is transmitted with at least one of the first PMI and the second PMI.