Method and apparatus for phase tracking

1. A method performed by a user equipment (UE), the method comprising:

transmitting coherent information of a communication device, wherein the coherent information indicates:

that the communication device uses a non-coherent transmission, and a number of antenna ports configured at the communication device being N; or

that the communication device uses a partial-coherent transmission, the number of coherent antenna groups configured at the communication device being M, and the number of antenna ports in each coherent antenna group; and

receiving configuration information for the communication device, wherein the configuration information is based at least on the coherent information, indicates a plurality of phase tracking reference signal ports assigned to the communication device, and a number of the plurality of phase tracking reference signal ports being M.

2. The method of claim 1 , further comprising:

transmitting phase tracking reference signal with v phase tracking reference signal ports selected from an N phase tracking reference signal ports, wherein v denotes the number of transmission layers.

3. The method of claim 2 , wherein each phase tracking reference signal port is associated with a transmission layer transmitted with a corresponded sounding reference signal port.

4. The method of claim 1 , further comprising:

transmitting phase tracking reference signal with k phase tracking reference signal ports, wherein k=min{v,M} and v denotes the number of transmission layers.

5. The method of claim 4 , wherein a phase tracking reference signal port i is associated with a transmission layer [xi] of transmission layers, transmitted with sounding reference signal ports within ith coherent antenna group.

6. The method of claim 5 , wherein the configuration information further includes downlink control information including a parameter indicating a value of [xi].

7. The method of claim 6 , wherein the parameter has a bitwidth of Σ i=1 min{v,M} ┌log 2 (S 1 )┐ comprised of min{v,M} parts, wherein S i denotes the number of antenna ports in ith coherent antenna group.

8. The method of claim 7 , wherein the value of [xi] is indicated in an ith part of the parameter.

9. A method performed by a base station, the method comprising:

receiving coherent information of a communication device, wherein the coherent information indicates:

that the communication device uses a non-coherent transmission, and a number of antenna ports configured at the communication device being N; or

that the communication device uses a partial-coherent transmission, the number of coherent antenna groups configured at the communication device being M, and the number of antenna ports in each coherent antenna group;

determining a plurality of phase tracking reference signal ports for the communication device based at least on the coherent information; and

transmitting configuration information to the communication device indicating the phase tracking reference signal ports assigned to the communication device, and a number of the plurality of phase tracking reference signal ports being M.

10. The method of claim 9 , wherein each phase tracking reference signal port is associated with a layer transmitted with a corresponded sounding reference signal port.

11. The method of claim 9 , wherein a phase tracking reference signal port i is associated with a transmission layer [xi] of transmission layers transmitted with sounding reference signal (SRS) ports within ith coherent antenna group.

12. The method of claim 11 , wherein the configuration information further includes downlink control information including a parameter indicating a value of [xi].

13. The method of claim 12 , wherein the parameter has a bitwidth of Σ i=1 min{v,M} ┌log 2 (S i )┐ comprising min{v,M} parts, wherein v denotes the number of transmission layers, and S i denotes the number of antenna ports in ith coherent antenna group.

14. The method of claim 13 , wherein the value of [xi] is indicated in an ith part of the parameter.

15. A user equipment (UE), comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the UE to:

transmit coherent information of the UE, wherein the coherent information indicates that:

the UE uses a non-coherent transmission, and a number of antenna ports configured at the UE being N; or

the UE uses a partial-coherent transmission, the number of coherent antenna groups configured at the UE being M, and the number of antenna ports in each coherent antenna group; and

receive configuration information for the UE, wherein the configuration information is based at least on the coherent information, indicates a plurality of phase tracking reference signal ports assigned to the UE, and a number of the plurality of phase tracking reference signal ports being M.

16. The UE of claim 15 , wherein the at least one processor is configured to cause the UE to:

transmit a phase tracking reference signal with v phase tracking reference signal ports selected from N phase tracking reference signal ports, wherein v denotes the number of transmission layers.

17. The UE of claim 16 , wherein the at least one processor is configured to cause the UE to associate each phase tracking reference signal port with a transmission layer transmitted with a corresponded sounding reference signal port.

18. A base station, comprising:

at least one memory; and

at least one processor coupled with the at least one memory and configured to cause the base station to:

receive coherent information of a communication device, wherein the coherent information indicates:

that the communication device uses a non-coherent transmission, and a number of antenna ports configured at the communication device being N; or

that the communication device uses a partial-coherent transmission, the number of coherent antenna groups configured at the communication device being M, and the number of antenna ports in each coherent antenna group;

determine a plurality of phase tracking reference signal ports for the communication device based at least on the coherent information; and

transmit configuration information to the communication device indicating the phase tracking reference signal ports assigned to the communication device, and a number of the plurality of phase tracking reference signal ports being M.