Method and apparatus for selecting a voice coding rate based on the air interface efficiency of the serving base station

1. A method for a user equipment (UE) device, comprising:

receiving, by the UE device and from a base station serving the UE device, information indicative of an air interface efficiency of the base station serving the UE device;

selecting, by the UE device, a voice coding rate for a voice call involving the UE device based on the information indicative of the air interface efficiency of the base station serving the UE device, the information further comprising at least one of a beamforming capability associated with the base station, a multi-user multiple-input multiple-output (MU-MIMO) capability associated with the base station, or an antenna configuration associated with the base station;

transmitting, by the UE device, an indication of the selected voice coding rate to the base station; and

transmitting, by the UE device, one or more voice frames to the base station during the voice call, wherein the one or more voice frames convey voice data coded at the selected voice coding rate.

2. The method of claim 1 , wherein the one or more factors indicative of the air interface efficiency of the base station include information indicative of the air interface efficiency of the base station serving the UE device comprises information indicative of a beamforming capability of the base station.

3. The method of claim 2 , wherein the information indicative of the beamforming capability of the base station comprises:

(i) an indication of a number of UE devices that the base station is currently beamforming to; and

(ii) an indication of a number of UE devices that the base station could potentially beamform to.

4. The method of claim 3 , further comprising:

wherein selecting, by the UE device, the voice coding rate for the voice call based on the information indicative of the air interface efficiency of the base station serving the UE device comprises:

determining, by the UE device, a beamforming capability index of the base station based on the number of UE devices that the base station is currently beamforming to and the number of UE devices that the base station could potentially beamform to, wherein the UE device has access to a mapping between a plurality of beamforming capability indexes and a plurality of voice coding rates, wherein the mapping maps each beamforming capability index to a respective voice coding rate; and

applying the mapping to map the beamforming capability index of the base station to one of the plurality of voice coding rates.

5. The method of claim 1 , wherein the one or more factors indicative of the air interface efficiency of the base station include information indicative of the air interface efficiency of the base station serving the UE device comprises information indicative of a multi-user multiple-input multiple-output (MU-MIMO) capability of the base station.

6. The method of claim 5 , wherein the information indicative of the MU-MIMO capability of the base station comprises:

(i) an indication of a number of UE devices that are currently being paired for MU-MIMO by the base station and

(ii) an indication of a number of UE devices that could potentially be paired for MU-MIMO by the base station.

7. The method of claim 6 , wherein selecting, by the UE device, the voice coding rate for the voice call based on the information indicative of the air interface efficiency of the base station serving the UE device comprises:

determining, by the UE device, a MU-MIMO capability index of the base station based on the number of UE devices that are currently being paired for MU-M IMO by the base station and the number of UE devices that could potentially be paired for MU-M IMO by the base station, wherein the UE device has access to a mapping between a plurality of MU-MIMO capability indexes and a plurality of voice coding rates, wherein the mapping maps each MU-MIMO capability index to a respective voice coding rate; and

applying the mapping to map the MU-M IMO capability index of the base station to one of the plurality of voice coding rates.

8. The method of claim 1 , wherein the information indicative of the air interface efficiency of the base station serving the UE device comprises information indicative of an antenna configuration of the base station.

9. The method of claim 8 , wherein the information indicative of the antenna configuration of the base station comprises:

an indication of a number of transmit antennas of the base station; and

an indication of a number of receive antennas of the base station.

10. The method of claim 9 , wherein selecting, by the UE device, the voice coding rate for the voice call based on the information indicative of the air interface efficiency of the base station serving the UE device comprises:

determining, by the UE device, an antenna configuration index of the base station based on the number of transmit antennas of the base station and the number of receive antennas of the base station, wherein the UE device has access to a mapping between a plurality of antenna configuration indexes and a plurality of voice coding rates, wherein the mapping maps each antenna configuration index to a respective voice coding rate; and

applying the mapping to map the antenna configuration index of the base station to one of the plurality of voice coding rates.

11. The method of claim 1 , further comprising:

receiving, by the UE device and during the voice call, information indicative of a new air interface efficiency;

selecting, by the UE device, a new voice coding rate for the voice call based on the new air interface efficiency; and

transmitting, by the UE device, one or more subsequent voice frames during the voice call, wherein the one subsequent voice frames convey voice data coded at the new voice coding rate.

12. A user equipment (UE) device, comprising:

a wireless communication interface;

a processor;

data storage;

program instructions stored in the data storage and executable by the processor to cause the UE device to perform functions, the functions comprising:

receiving, via the wireless communication interface and from a base station serving the UE device, information indicative of an air interface efficiency data of the base station serving the UE device, the information further comprising at least one of a beamforming capability associated with the base station, a multi-user multiple-input multiple-output (MU-MIMO) capability associated with the base station, or an antenna configuration associated with the base station; and

selecting, based on the information indicative of the air interface efficiency of the base station serving the UE device, a voice coding rate for a voice call involving the UE device.

13. The UE device of claim 12 , wherein the information indicative of the air interface efficiency of the base station serving the UE device comprises information indicative of a beamforming capability of the base station.

14. The UE device of claim 13 , wherein the information indicative of the beamforming capability of the base station comprises:

(i) an indication of a number of UE devices that the base station is currently beamforming to; and

(ii) an indication of a number of UE devices that the base station could potentially beamform to.

15. The UE device of claim 14 , wherein selecting, based on information indicative of the air interface efficiency of the base station serving the UE device, the voice coding rate for the voice call involving the UE device comprises:

determining a beamforming capability index of the base station based on the number of UE devices that the base station is currently beamforming to and the number of UE devices that the base station could potentially beamform to, wherein the UE device has access to a mapping between a plurality of beamforming capability indexes and a plurality of voice coding rates, wherein the mapping maps each beamforming capability index to a respective voice coding rate; and

applying the mapping to map the beamforming capability index of the base station to one of the plurality of voice coding rates.

16. The UE device of claim 12 , wherein the information indicative of the air interface efficiency of the base station serving the UE device comprises information indicative of a multi-user multiple-input multiple-output (MU-MIMO) capability of the base station.

17. The UE device of claim 16 , wherein the information indicative of the MU-MIMO capability of the base station comprises:

(i) an indication of a number of UE devices that are currently being paired for MU-MIMO by the base station; and

(ii) an indication of a number of UE devices that could potentially be paired for MU-MIMO by the base station.

18. The UE device of claim 17 , wherein selecting, based on information indicative of the air interface efficiency of the base station serving the UE device, the voice coding rate for the voice call involving the UE device comprises:

determining a MU-MIMO capability index of the base station based on the number of UE devices that are currently being paired for MU-MIMO by the base station and the number of UE devices that could potentially be paired for MU-MIMO by the base station, wherein the UE device has access to a mapping between a plurality of MU-MIMO capability indexes and a plurality of voice coding rates, wherein the mapping maps each MU-MIMO capability index to a respective voice coding rate; and

applying the mapping to map the MU-MIMO capability index of the base station to one of the plurality of voice coding rates.

19. The UE device of claim 12 , information indicative of the air interface efficiency of the base station serving the UE device comprises information indicative of an antenna configuration of the base station, and wherein the information indicative of the antenna configuration of the base station comprises an indication of a number of transmit antennas of the base station and an indication of a number of receive antennas of the base station.

20. The UE device of claim 19 , wherein selecting, based on information indicative of the air interface efficiency of the base station serving the UE device, the voice coding rate for the voice call involving the UE device comprises:

determining an antenna configuration index of the base station based on the number of transmit antennas of the base station and the number of receive antennas of the base station, wherein the UE device has access to a mapping between a plurality of antenna configuration indexes and a plurality of voice coding rates, wherein the mapping maps each antenna configuration index to a respective voice coding rate; and

applying the mapping to map the antenna configuration index of the base station to one of the plurality of voice coding rates.