Channel-sounding method using a plurality of antennas, and apparatus for same
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.
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 for the multiple antenna ports 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 the sounding reference sequences for a first group of antenna ports among the multiple antenna ports are mapped to a set of every two resource elements in the SC-FDMA symbol of the subframe,
sounding reference sequences for a second group of antenna ports among the multiple antenna ports are mapped to another set of every two resource elements in the SC-FDMA symbol of the subframe,
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 sounding reference sequences for the multiple antenna ports are mapped to a same set of every two resource elements in the SC-FDMA symbol of the subframe.
3. The method of claim 1 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe.
4. 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 for the multiple antenna ports from the resource elements of a corresponding antenna port of the multiple antenna ports on the SC-FDMA symbol of the subframe,
wherein the sounding reference sequences for a first group of antenna ports among the multiple antenna ports are de-mapped from a set of every two resource elements in the SC-FDMA symbol of the subframe,
sounding reference sequences for a second group of antenna ports among the multiple antenna ports are de-mapped from another set of every two resource elements in the SC-FDMA symbol of the subframe,
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.
5. The method of claim 4 , wherein the sounding reference sequences for the multiple antenna ports are mapped to a same set of every two resource elements in the SC-FDMA symbol of the subframe.
6. The method of claim 4 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe.
7. The method of claim 4 , further comprising:
estimating an uplink channel state using the de-mapped sounding reference sequences.
8. 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 for the multiple antenna ports 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 the sounding reference sequences for a first group of antenna ports among the multiple antenna ports are mapped to a set of every two resource elements in the SC-FDMA symbol of the subframe,
sounding reference sequences for a second croup of antenna ports among the multiple antenna ports are mapped to another set of every two resource elements in the SC-FDMA symbol of the subframe,
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 UE of claim 8 , wherein the sounding reference sequences for the multiple antenna ports are mapped to a same set of every two resource elements in the SC-FDMA symbol of the subframe.
10. The UE of claim 8 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe.
11. 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 for the multiple antenna ports from the resource elements of a corresponding antenna port of the multiple antenna ports on the SC-FDMA symbol of the subframe,
wherein the sounding reference sequences for a first group of antenna ports among the multiple antenna ports are de-mapped from a set of every two resource elements in the SC-FDMA symbol of the subframe,
sounding reference sequences for a second group of antenna ports among the multiple antenna ports are de-mapped from another set of every two resource elements in the SC-FDMA symbol of the subframe,
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.
12. The BS of claim 11 , wherein the sounding reference sequences for the multiple antenna ports are mapped to a same set of every two resource elements in the SC-FDMA symbol of the subframe.
13. The BS of claim 11 , wherein the SC-FDMA symbol is a last SC-FDMA symbol of the subframe.
14. The BS of claim 11 , wherein the processor is further configured to estimate an uplink channel state using the de-mapped sounding reference sequences.