Method and apparatus for obtaining channel quality indication

1. A method for obtaining a Channel Quality Indication (CQI) in a communication system, wherein the communication system comprises a user equipment (UE), a coordinated multi-point (CoMP) measurement set including more than one base station (BS)/point, and one or more outside BSs/points which is outside the CoMP measurement set, and wherein the UE is served by a serving BS/point in the CoMP measurement set and interfered by at least one interfering BS/point in the CoMP measurement set and the one or more outside BSs/points, the method comprising:

estimating a first interference from at least one outside BS/point which is outside the CoMP measurement set to the UE;

estimating a second interference from at least one interfering BS/point in the CoMP measurement set to the UE; and

obtaining a target CQI based on the first interference and the second interference,

wherein estimating the first interference from the at least one outside BS/point which is outside the CoMP measurement set to the UE comprises:

measuring channel information of a channel from the serving BS/point to the UE;

acquiring CQIs indicating quality of channels from BSs/points in the CoMP measurement set to the UE; and

estimating the first interference based on the measured channel information and the acquired CQIs.

2. The method of claim 1 , wherein estimating the first interference from the at least one outside BS/point which is outside the CoMP measurement set to the UE further comprises:

acquiring a CQI indicating quality of a channel from a reference BS/point to the UE, wherein the reference BS/point belongs to the at least one interfering BS/point in the CoMP measurement set;

acquiring a transmission power of the reference BS/point to the UE, a transmission power of the serving BS/point to the UE, a path loss of the reference BS/point to the UE, and a path loss of the serving BS/point to the UE; and

estimating the first interference based on the measured channel information, the acquired CQI, the transmission power of the reference BS/point to the UE, the transmission power of the serving BS/point to the UE, the path loss of the reference BS/point to the UE, and the path loss of the serving BS/point to the UE.

3. The method of claim 2 , wherein measuring channel information of the channel from the serving BS/point to the UE comprises:

receiving an uplink sounding reference signal from the UE; and

measuring the channel information based on the uplink sounding reference signal.

4. The method of claim 1 , wherein measuring channel information of the channel from the serving BS/point to the UE comprises:

receiving an uplink sounding reference signal from the UE; and

measuring the channel information based on the uplink sounding reference signal.

5. The method of claim 1 , wherein estimating the second interference from the at least one interfering BS/point in the CoMP measurement set to the UE comprises:

acquiring a beamforming matrix for transmission from the at least one interfering BS/point to the UE;

acquiring transmission powers of BSs/points in the CoMP measurement set to the UE, path losses of the BSs/points in the CoMP measurement set to the UE, and channel information of a channel from the at least one interfering BS/point to the UE; and

estimating the second interference based on the transmission powers of the BSs/points in the CoMP measurement set to the UE, the path losses of the BSs/points in the CoMP measurement set to the UE, the acquired beamforming matrix and the acquired channel information.

6. The method of claim 1 , wherein obtaining the target CQI based on the first interference and the second interference comprises:

calculating beamforming gain from the serving BS/point to the UE;

calculating quality of a channel from the serving BS/point to the UE according to the first interference, the second interference and the beamforming gain; and

obtaining the target CQI based on the calculated quality.

7. The method of claim 6 , wherein calculating the quality of the channel from the serving BS/point to the UE according to the first interference, the second interference and the beamforming gain comprises:

updating the second interference based on scheduling of the UE by the at least one interfering BS; and

calculating the quality of a channel from the serving BS/point to the UE according to the first interference, the updated second interference and the beamforming gain.

8. The method of claim 7 , wherein updating the second interference based on scheduling of the UE by the at least one interfering BS/point comprises:

obtaining a scheduling result which comprises information on scheduling of the UE by the at least one interfering BS;

acquiring a beamforming matrix for transmission from the at least one interfering BS/point to the UE based on the scheduling result;

estimating a third interference based on the acquired beamforming matrix, channel information of a channel from the at least one interfering BS/point to the UE, transmission powers of BSs/points in the CoMP measurement set to the UE, and path losses of the BSs/points in the CoMP measurement set to the UE; and

updating the second interference with the third interference.

9. An apparatus for obtaining a Channel Quality Indication (CQI) in a communication system, wherein the communication system comprises a user equipment (UE), a coordinated multi-point (CoMP) measurement set including more than one base station (BS)/point, and one or more outside BSs/points which is outside the CoMP measurement set, and wherein the UE is served by a serving BS/point in the CoMP measurement set and interfered by at least one interfering BS/point in the CoMP measurement set and the one or more outside BSs/points, the apparatus comprising:

at least one non-transitory memory operable to store program code; and

at least one processor operable to read said program code and operate as instructed by said program code to:

estimate a first interference from at least one outside BS/point which is outside the CoMP measurement set to the UE;

estimate a second interference from at least one interfering BS/point in the CoMP measurement set to the UE; and

obtain a target CQI based on the first interference and the second interference,

wherein the operation of estimating the first interference comprises:

measuring channel information of a channel from the serving BS/point to the UE;

acquiring CQIs indicating quality of channels from BSs/points in the CoMP measurement set to the UE; and

estimating the first interference based on the measured channel information and the acquired CQIs.

10. The apparatus of claim 9 , wherein the operation of estimating the first interference further comprises:

acquiring a CQI indicating quality of a channel from a reference BS/point to the UE, wherein the reference BS/point belongs to the at least one interfering BS/point in the CoMP measurement set;

acquiring a transmission power of the reference BS/point to the UE, a transmission power of the serving BS/point to the UE, a path loss of the reference BS/point to the UE, and a path loss of the serving BS/point to the UE; and

estimating the first interference based on the measured channel information, the acquired CQI, the transmission power of the reference BS/point to the UE, the transmission power of the serving BS/point to the UE, the path loss of the reference BS/point to the UE, and the path loss of the serving BS/point to the UE.

11. The apparatus of claim 10 , wherein operation of measuring the channel information of the channel from the serving BS/point to the UE comprises:

receiving an uplink sounding reference signal from the UE; and

measuring the channel information based on the uplink sounding reference signal.

12. The apparatus of claim 9 , wherein the operation of measuring the channel information of the channel from the serving BS/point to the UE comprises:

receiving an uplink sounding reference signal from the UE; and

measuring the channel information based on the uplink sounding reference signal.

13. The apparatus of claim 9 , wherein the operation of estimating the first interference based on the measured channel information comprises:

acquiring a beamforming matrix for transmission from the at least one interfering BS/point to the UE;

acquiring transmission powers of BSs/points in the CoMP measurement set to the UE, path losses of the BSs/points in the CoMP measurement set to the UE, and channel information of a channel from the at least one interfering BS/point to the UE; and

estimating the second interference based on the transmission powers of the BSs/points in the CoMP measurement set to the UE, the path losses of the BSs/points in the CoMP measurement set to the UE, the acquired beamforming matrix and the acquired channel information.

14. The apparatus of claim 9 , wherein the operation obtaining the target CQI based on the first interference and the second interfere comprises:

beamforming gain from the serving BS/point to the UE;

calculating quality of a channel from the serving BS/point to the UE according to the first interference, the second interference and the beamforming gain; and

obtaining the target CQI based on the calculated quality.

15. The apparatus of claim 14 , wherein the operation of calculating the quality of the channel from the serving BS/point to the UE comprises:

updating the second interference based on scheduling of the UE by the at least one interfering BS; and

calculating the quality of a channel from the serving BS/point to the UE according to the first interference, the updated second interference and the beamforming gain.

16. The apparatus of claim 15 , wherein the operation of updating the second interference based on scheduling of the UE comprises:

obtaining a scheduling result which comprises information on scheduling of the UE by the at least one interfering BS;

acquiring a beamforming matrix for transmission from the at least one interfering BS/point to the UE based on the scheduling result;

estimating a third interference based on the acquired beamforming matrix, channel information of a channel from the at least one interfering BS/point to the UE, transmission powers of BSs/points in the CoMP measurement set to the UE, and path losses of the BSs/points in the CoMP measurement set to the UE; and

updating the second interference with the third interference.