Method and apparatus in which user equipment transmits feedback information in a distributed antenna system

Patent metadata

Field	Value
Publication number	US-9306649-B2
Application number	US-201113637215-A
Country	US
Kind code	B2
Filing date	Mar 23, 2011
Priority date	Mar 25, 2010
Publication date	Apr 5, 2016
Grant date	Apr 5, 2016

Abstract

Provided is a method for transmitting feedback information of a UE in a distributed antenna system in which a plurality of antennas are distributedly disposed within a cell is provided. The method includes transmitting first feedback information used for a base station (BS) to allocate at least one of a plurality of antennas to a UE, to the BS; receiving antenna allocation information determined based on the first feedback information from the BS; and transmitting second feedback information indicating a channel state with respect to an antenna allocated according to the antenna allocation information to the BS.

First claim

The invention claimed is:

1. A method for transmitting feedback information of a user equipment (UE) in a distributed antenna system in which a plurality of antennas are distributed within a cell and are controlled by a base station (BS), the method comprising:
transmitting, to the BS, first feedback information for the plurality of antennas, the first feedback information being used by the BS to allocate at least one of the plurality of antennas to the UE;
receiving, from the BS, antenna allocation information determined based on the first feedback information; and
transmitting, to the BS, second feedback information indicating a channel state with respect to the at least one of the plurality of antennas allocated to the UE according to the antenna allocation information,
wherein, when the UE does not receive control information to configure a transmission power of a sounding reference signal (SRS) from the BS, the first feedback information includes the SRS and SRS power information indicating the transmission power of the SRS,
wherein, when the UE receives the control information from the BS, the first feedback information includes the SRS without the SRS power information,
wherein, when the BS transmits the control information to the UE, the SRS power information is determined by the BS without feedback based on the control information transmitted to the UE, and
wherein the at least one of the plurality of antennas is allocated selected based on the SRS and the SRS power information.

2. The method of claim 1 ,
wherein the first feedback information further includes information related to:
an effective antenna of the plurality of antennas, the effective antenna being an antenna transmitting a reference signal that exceeds a threshold value as measured by the UE,
a downlink channel coefficient with respect to the effective antenna,
a reception noise strength measured by the UE,
a downlink channel size or signal strength with respect to the effective antenna, and
an index of an antenna of the plurality of antennas preferred by the UE, and
wherein the information related to the downlink channel coefficient, the downlink channel size or the signal strength are transmitted as values normalized with the reception noise strength measured by the UE.

3. The method of claim 1 , further comprising:
receiving a sounding reference signal transmission request from the BS,
wherein the sounding reference signal transmission request includes the control information.

4. The method of claim 1 , wherein the second feedback information includes at least one of a CQI (channel quality indicator) or a PMI (precoding matrix index) with respect to the allocated at least one of the plurality of antennas.

5. The method of claim 4 , wherein the first feedback information is transmitted with a first feedback information transmission period, the second feedback information is transmitted with a second feedback information transmission period, and the first feedback information transmission period is longer than the second feedback information transmission period.

6. The method of claim 4 , wherein the first feedback information is transmitted with a first feedback information transmission period, the second feedback information is transmitted with a second feedback information transmission period, and the first feedback information transmission period and the second feedback information transmission period are equal.

7. The method of claim 6 , wherein the first feedback information and the second feedback information are transmitted in a same subframe.

8. The method of claim 6 , wherein the second feedback information is transmitted after a fixed number of subframes from a subframe in which the first feedback information is transmitted.

9. The method of claim 1 , wherein the antenna allocation information includes allocation information regarding at least one of an antenna node allocated to the UE, an antenna group allocated to the UE, an antenna port allocated to the UE, or a virtual antenna allocated to the UE.

10. A user equipment (UE) configured to transmit feedback information of the UE in a distributed antenna system in which a plurality of antennas are distributed within a cell and are controlled by a base station (BS), the UE comprising:
a radio frequency (RF) unit; and
a processor operatively connected to the RF unit and configured to:
transmit, to the BS, first feedback information for the plurality of antennas, the first feedback information being used by the BS to allocate at least one of the plurality of antennas to the UE;
receive, from the BS, antenna allocation information determined based on the first feedback information; and
transmit, to the BS, second feedback information indicating a channel state with respect to the at least one of the plurality of antennas allocated to the UE according to the antenna allocation information,
wherein, when the UE does not receive control information to configure a transmission power of a sounding reference signal (SRS) from the BS, the first feedback information includes the SRS and SRS power information indicating the transmission power of the SRS,
wherein, when the UE receives the control information from the BS, the first feedback information includes the SRS without the SRS power information,
wherein, when the BS transmits the control information to the UE, the SRS power information is determined by the BS without feedback based on the control information transmitted to the UE, and
wherein the at least one of the plurality of antennas is allocated based on the SRS and the SRS power information.

11. The UE of claim 10 , wherein the first feedback information further includes information related to:
an effective antenna of the plurality of antennas, the effective antenna being an antenna transmitting a reference signal that exceeds a threshold value as measured by the UE,
a downlink channel coefficient with respect to the effective antenna,
a reception noise strength measured by the UE,
a downlink channel size or signal strength with respect to the effective antenna, and
an index of an antenna of the plurality of antennas preferred by the UE, and
wherein the information related to the downlink channel coefficient, the downlink channel size or the signal strength are transmitted as values normalized with the reception noise strength measured by the UE.

12. The UE of claim 10 , wherein the second feedback information includes at least one of a CQI (channel quality indicator) or a PMI (precoding matrix index) with respect to the allocated at least one of the plurality of antennas.

13. The UE of claim 12 , wherein the first feedback information is transmitted with a first feedback information transmission period, the second feedback information is transmitted with a second feedback information transmission period, and the first feedback information transmission period is longer than the second feedback information transmission period.

14. The UE of claim 12 , wherein the first feedback information is transmitted with a first feedback information transmission period, the second feedback information is transmitted with a second feedback information transmission period, and the first feedback information transmission period and the second feedback information transmission period are equal.

Assignees

• Kang Ji Won
• Chun Jin Young
• Kim Su Nam
• Ihm Bin Chul
• Park Sung Ho
• Lg Electronics Inc

Inventors

• Kang Ji Won
• Chun Jin Young
• Kim Su Nam
• Ihm Bin Chul
• Park Sung Ho

Classifications

• H04B7/0626 Primary

  Channel coefficients, e.g. channel state information [CSI] · CPC title

• H04B7/0645

  Variable feedback · CPC title

• H04B7/0691

  using subgroups of transmit antennas · CPC title

• H04B7/0623

  Auxiliary parameters, e.g. power control [PCB] or not acknowledged commands [NACK], used as feedback information · CPC title

• H04B7/024 Primary

  Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems · CPC title