Method and apparatus for transmitting measurement report in a wireless communication system

1. A method for transmitting a measurement report at a User Equipment (UE) in a wireless communication system supporting a coordinated multi-point (CoMP), the method comprising:

measuring, by the UE, received strengths and reception frequencies of first and second signals respectively transmitted from first and second transmission points in a CoMP measurement set;

calculating a frequency offset between the reception frequencies; and

transmitting, by the UE to the first transmission point, a measurement report including information on the frequency offset between the first and second signals, if the received strength of the second signal is equal to or larger than a predetermined threshold,

wherein the information on the frequency offset is used to support cooperative transmission of transmission points transmitting the first and second signals, and

wherein a transmission period for the measurement report is determined based on a frequency offset change rate.

2. The method according to claim 1 , wherein the support of cooperative transmission includes at least one of determination as to whether the transmission points are to perform cooperative transmission, determination of a cooperative transmission scheme of the transmission points, or correction of transmission frequencies of one or more of the transmission points.

3. The method according to claim 1 , wherein the first signal is a cell-specific reference signal transmitted by a first transmission point being a serving cell of the UE and the second signal is a cell-specific reference signal transmitted by a second transmission point being neighbor cell of the serving cell.

4. The method according to claim 3 , wherein the second transmission point is included in a neighbor cell list received from the first transmission point.

5. The method according to claim 3 , wherein the second transmission point is indicated in a neighbor cell list received from the first transmission point by the first transmission point.

6. The method according to claim 1 , wherein the first and second signals are Channel State Information-Reference Signals (CSI-RSs).

7. The method according to claim 6 , wherein the first and second signals are indicated for frequency offset reporting in a CSI-RS list related to cooperative transmission.

8. The method according to claim 7 , wherein the first signal is a first CSI-RS listed in the CSI-RS list.

9. The method according to claim 8 , wherein the CSI-RS list includes a plurality of CSI-RS configurations.

10. The method according to claim 1 ,

wherein the measurement report further includes a Reference Signal Time Difference (RSTD) between the transmission points transmitting the first and second signals, and

wherein the RSTD is used to support the cooperative transmission.

11. The method according to claim 10 , wherein the RSTD is the difference between the starts of subframes received from the transmission points.

12. The method according to claim 1 , wherein the cooperative transmission is joint transmission.

13. The method according to claim 1 , further comprising:

measuring, by the UE, a phase offset of the first and second signals; and

transmitting, by the UE to the first transmission point, information on the phase offset when the frequency offset is less than a predetermined value.

14. A User Equipment (UE) in a wireless communication system supporting a coordinated multi-point (CoMP), comprising:

a transmitter; and

a processor, wherein the processor is configured to:

measure received strengths and reception frequencies of first and second signals respectively transmitted from first and second transmission points in a CoMP measurement set,

calculate a frequency offset between the reception frequencies, and

transmit a measurement report to the first transmission point, the measurement report including information on the frequency offset between the first and second signals, if the received strength of the second signal is equal to or larger than a predetermined threshold,

wherein the information on the frequency offset is used to support cooperative transmission of transmission points transmitting the first and second signals, and

wherein a transmission period for the measurement report is determined based on a frequency offset change rate.

15. A method for receiving a measurement report, by a first transmission point in a wireless communication system supporting a coordinated multi-point (CoMP), the method comprising:

receiving a measurement report from a User Equipment (UE) that has received first and second signals respectively transmitted from first and second transmission points in a CoMP measurement set,

wherein the measurement report includes a frequency offset between the first and second signals, if the received strength of the second signal is equal to or larger than a predetermined threshold,

wherein the information on the frequency offset is used to support cooperative transmission of transmission points transmitting the first and second signals, and

wherein a transmission period for the measurement report is determined based on a frequency offset change rate.

16. A first transmission point in a wireless communication system supporting a coordinated multi-point (CoMP), comprising:

a receiver; and

a processor, wherein the processor is configured to:

receive a measurement report from a User Equipment (UE) that has received first and second signals respectively transmitted from first and second transmission points in a CoMP measurement set,

wherein the measurement report includes information on a frequency offset between the first and second signals, if the received strength of the second signal is equal to or larger than a predetermined threshold,

wherein the frequency offset is used to support cooperative transmission of transmission points transmitting the first and second signals, and

wherein a transmission period for the measurement report is determined based on a frequency offset change rate.