Reference Signal for a Coordinated Multi-Point Network Implementation

1. A method of operating a user equipment (UE) in a wireless communications network, the method comprising: receiving, by the UE, a first channel state information reference signal (CSI-RS) transmitted from a base station, the first CSI-RS being transmitted at a first periodicity using a first set of antenna ports; receiving, by the UE, a second CSI-RS transmitted from the base station, the second CSI-RS being transmitted at a second periodicity using a second set of antenna ports, wherein the second set of antenna ports comprises fewer ports than the first set of antenna ports, and the second periodicity is greater than the first periodicity; determining the UE moves relative to the base station at a speed greater than a threshold; and in response to the determining, using, by UE, the second CSI-RS to perform channel measurement.

2. The method of claim 1 , wherein the first CSI-RS is transmitted in a first resource of a first radio frame.

3. The method of claim 2 , wherein the second CSI-RS is transmitted in a second resource of a second radio frame.

4. The method of claim 3 , wherein the first radio frame and the second radio frame are the same radio frame.

5. The method of claim 3 , wherein the first resource and the second resource are transmitted in the same subframe of a radio frame.

6. The method of claim 1 , wherein the second set of antenna ports is a subset of the first set of antenna ports.

7. The method of claim 1 , including receiving an instruction from the base station identifying the second CSI-RS to use for channel measurement.

8. The method of claim 7 , including transmitting a channel measurement report to the base station, the measurement report indicating the channel measurement is based on the second CSI-RS for channel.

9. The method of claim 1 , including: receiving an antenna mapping from the base station, the antenna mapping identifying the second set of antenna ports.

10. The method of claim 1 , wherein the second set of antenna ports includes a virtual antenna comprising a combination of two or more antenna ports from the first set of antenna ports.

11. The method of claim 1 , including: receiving an identification from the base station of a third CSI-RS of a neighbor cell, wherein the third CSI-RS is received in one or more resource elements; and muting at least one of the one or more resource elements corresponding to the third CSI-RS.

12. A method of operating a base station in a wireless communications network, the method comprising: transmitting, by a base station, a first channel state information reference signal (CSI-RS) to a user equipment, the first CSI-RS being transmitted at a first periodicity using a first set of antenna ports; transmitting, from by the base station, a second CSI-RS to the user equipment, the second CSI-RS being transmitted at a second periodicity using a second set of antenna ports, wherein the second set of antenna ports comprises fewer ports than the first set of antenna ports, and the second periodicity is greater than the first periodicity; and receiving, by the base station, a channel measurement report from the user equipment, the channel measurement report being based upon the second CSI-RS used when the UE moves relative to the base station at a speed greater than a threshold.

13. The method of claim 12 , wherein the first CSI-RS is transmitted in a first resource of a first radio frame.

14. The method of claim 13 , wherein the second CSI-RS is transmitted within a second resource of a second radio frame.

15. The method of claim 14 , wherein the first radio frame and the second radio frame are the same radio frame.

16. The method of claim 14 , wherein the first resource and the second resource are in the same subframe of a radio frame.

17. The method of claim 12 , wherein the second set of antenna ports is a subset of the first set of antenna ports.

18. The method of claim 12 , including transmitting an instruction to the user equipment identifying the second CSI-RS to use for channel measurement.

19. The method of claim 18 , including using the received channel measurement report to determine that the measurement report is based on the second CSI-RS to use for channel measurement.

20. The method of claim 12 , including: transmitting an antenna mapping to the user equipment, the antenna mapping identifying the second set of antenna ports.

21. The method of claim 12 , wherein the second set of antenna ports includes a virtual antenna comprising a combination of two or more antenna ports from the first set of antenna ports.

22. The method of claim 12 , wherein the second set of antenna ports is a subset of the first set of antenna ports.

23. The method of claim 12 , including, when a load on the base station exceeds a predetermined threshold, decreasing a frequency of the second periodicity.

24. The method of claim 12 , including, when a load on the base station falls below a predetermined threshold, increasing a frequency of the second periodicity.

25. A user equipment, comprising: a processor configured to communicate with a memory, the memory storing instructions, which when executed by the processor, cause the processor to perform the steps of: receiving a first channel state information reference signal (CSI-RS) transmitted from a base station, the first CSI-RS being transmitted at a first periodicity using a first set of antenna ports; receiving a second CSI-RS transmitted from the base station, the second CSI-RS being transmitted at a second periodicity using a second set of antenna ports, wherein the second set of antenna ports comprises fewer ports than the first set of antenna ports, and the second periodicity is greater than the first periodicity; determining the UE moves relative to the base station at a speed greater than a threshold; and in response to the determining, using, by the user equipment, the second CSI-RS to perform channel measurement.

26. The user equipment of claim 25 , wherein the first CSI-RS is transmitted in a first resource of a first radio frame.

27. The user equipment of claim 26 , wherein the second CSI-RS is transmitted in a second resource of a second radio frame.

28. The user equipment of claim 27 , wherein the first radio frame and the second radio frame are the same radio frame.

29. The user equipment of claim 27 , wherein the first resource and the second resource are transmitted in the same subframe of a radio frame.

30. A base station, comprising: a processor configured to communicate with a memory, the memory storing instructions, which when executed by the processor, cause the processor to perform the steps of: transmitting a first CSI-RS to a user equipment, the first CSI-RS being transmitted at a first periodicity using a first set of antenna ports; transmitting a second CSI-RS to the user equipment, the second CSI-RS being transmitted at a second periodicity using a second set of antenna ports, wherein the second set of antenna ports comprises fewer ports than the first set of antenna ports, and the second periodicity is greater than the first periodicity; and receiving a channel measurement report from the user equipment, the channel measurement report being based upon the second CSI-RS used when the UE moves relative to the base station at a speed greater than a threshold.

31. The base station of claim 30 , wherein the first CSI-RS is transmitted in a first resource of a first radio frame.

32. The base station of claim 31 , wherein the second CSI-RS is transmitted within a second resource of a second radio frame.

33. The base station of claim 32 , wherein the first radio frame and the second radio frame are the same radio frame.

34. The base station of claim 32 , wherein the first resource and the second resource are in the same subframe of a radio frame.