Channel-sounding method using a plurality of antennas, and apparatus for same

Abstract

The present invention relates to a wireless communication system. More particularly, the present invention relates to a method and to an apparatus for transmitting an SRS in a multi-antenna system. The method comprises the steps of: acquiring specific information for discriminating a first antenna group and a second antenna group from among a plurality of antennas, wherein said first antenna group includes one or more antennas which are set to a turned-on state to perform communication with a base station, and said second antenna group includes one or more other antennas which are set to a turned-off state; transmitting an SRS to the base station if a predetermined condition is satisfied, under the condition that the second antenna group is set to the turned-off state; and setting the second antenna group to a turned-off state after the transmission of the SRS.

The invention claimed is:  
     
       1. A method of transmitting sounding reference signals in a wireless communication system, the method comprising:
 generating, by a user equipment (UE), sounding reference sequences for multiple antenna ports of the UE, 
 wherein each sounding reference sequence is defined using a base sequence number and a cyclic shift value; 
 mapping, by the UE, each sounding reference sequence to resource elements of a corresponding antenna port of the multiple antenna ports on a single carrier frequency division multiple access (SC-FDMA) symbol of a subframe; and 
 transmitting, by the UE, the sounding reference sequences for the multiple antenna ports within the SC-FDMA symbol of the subframe, 
 wherein sounding reference sequences for a first group of antenna ports among the multiple antenna ports are mapped to a first set of every two resource elements in the SC-FDMA symbol of the subframe, 
 wherein sounding reference sequences for a second group of antenna ports among the multiple antenna ports are mapped to a second set of every two resource elements in the SC-FDMA symbol of the subframe, the second set being different from the first set, 
 wherein the cyclic shift value is defined for each antenna port within N cyclic shift values based on a signaled value and an offset corresponding to each antenna port of the multiple antenna ports, and 
 wherein N is a predetermined positive integer equal to or greater than 2. 
 
     
     
       2. The method of  claim 1 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe. 
     
     
       3. A method of processing sounding reference signals in a wireless communication system, the method comprising:
 receiving, by a base station (BS), sounding reference sequences for multiple antenna ports of a user equipment (UE) on resource elements of a single carrier frequency division multiple access (SC-FDMA) symbol of a subframe, 
 wherein each sounding reference sequence is defined using a base sequence number and a cyclic shift value; and 
 de-mapping, by the BS, each sounding reference sequence from the resource elements of a corresponding antenna port of the multiple antenna ports on the SC-FDMA symbol of the subframe, 
 wherein sounding reference sequences for a first group of antenna ports among the multiple antenna ports are de-mapped from a first set of every two resource elements in the SCFDMA symbol of the subframe, 
 wherein sounding reference sequences for a second group of antenna ports among the multiple antenna ports are de-mapped from a second set of every two resource elements in the SC-FDMA symbol of the subframe, the second set being different from the first set, 
 wherein the cyclic shift value is defined for each antenna port within N cyclic shift values based on a signaled value and an offset corresponding to each antenna port of the multiple antenna ports, and 
 wherein N is a predetermined positive integer equal to or greater than 2. 
 
     
     
       4. The method of  claim 3 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe. 
     
     
       5. The method of  claim 3 , further comprising:
 estimating an uplink channel state using the de-mapped sounding reference sequences. 
 
     
     
       6. A user equipment (UE) for use in a wireless communication system, the UE comprising:
 a radio frequency (RF) unit configured to transmit signals; and 
 a processor, configured to:
 generate sounding reference sequences for multiple antenna ports of the UE, 
 wherein each sounding reference sequence is defined using a base sequence number and a cyclic shift value; 
 map each sounding reference sequence to resource elements of a corresponding antenna port of the multiple antenna ports on a single carrier frequency division multiple access (SC-FDMA) symbol of a subframe; and 
 transmit the sounding reference sequences for the multiple antenna ports within the SC-FDMA symbol of the subframe, 
 wherein sounding reference sequences for a first group of antenna ports among the multiple antenna ports are mapped to a first set of every two resource elements in the SC-FDMA symbol of the subframe, 
 wherein sounding reference sequences for a second group of antenna ports among the multiple antenna ports are mapped to a second set of every two resource elements in the SC-FDMA symbol of the subframe, the second set being different from the first set, 
 wherein the cyclic shift value is defined for each antenna port within N cyclic shift values based on a signaled value and an offset corresponding to each antenna port of the multiple antenna ports, and 
 wherein N is a predetermined positive integer equal to or greater than 2. 
 
 
     
     
       7. The UE of  claim 6 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe. 
     
     
       8. A base station (BS) for use in a wireless communication system, the BS comprising:
 a radio frequency (RF) unit configured to transmit signals; and 
 a processor configured to:
 receive sounding reference sequences for multiple antenna ports of a user equipment (UE) on resource elements of a single carrier frequency division multiple access (SC-FDMA) symbol of a subframe, 
 wherein each sounding reference sequence is defined using a base sequence number and a cyclic shift value; and 
 de-map each sounding reference sequence from the resource elements of a corresponding antenna port of the multiple antenna ports on the SC-FDMA symbol of the subframe, 
 wherein sounding reference sequences for a first group of antenna ports among the multiple antenna ports are de-mapped from a first set of every two resource elements in the SCFDMA symbol of the subframe, 
 wherein sounding reference sequences for a second group of antenna ports among the multiple antenna ports are de-mapped from a second set of every two resource elements in the SC-FDMA symbol of the subframe, the second set being different from the first set, 
 wherein the cyclic shift value is defined for each antenna port within N cyclic shift values based on a signaled value and an offset corresponding to each antenna port of the multiple antenna ports, and 
 wherein N is a predetermined positive integer equal to or greater than 2. 
 
 
     
     
       9. The BS of  claim 8 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe. 
     
     
       10. The BS of  claim 8 , wherein the processor is further configured to estimate an uplink channel state using the de-mapped sounding-reference sequences.