Beam selection balancing maximum power exposure and link budget

1. A method for wireless communications by a user equipment (UE), comprising:

selecting, from a plurality of beams, a beam for uplink transmission during a particular time interval, the selecting being based on a transmission power and a radio frequency (RF) exposure for each of the plurality of beams, wherein the particular time interval is part of a moving time window and wherein the selecting is based on the transmission power of previous time intervals in the time window and the RF exposure, for each of the plurality of beams, for a prior time interval in the time window; and

transmitting at least one uplink signal using the selected beam during the particular time interval.

2. The method of claim 1 , further comprising repeating, for a subsequent interval after the particular time interval, the selection of the beam for uplink transmission during the subsequent time interval and the transmission of at least another uplink signal using the selected beam during the subsequent time interval.

3. The method of claim 1 , wherein the plurality of beams comprises a plurality of antenna modules of the UE and wherein the selecting comprises selecting one of the plurality of antenna modules for the uplink transmission.

4. The method of claim 1 , wherein the transmission power of the previous time intervals comprises an effective isotropic radiated power (EIRP) of the previous time intervals in the time window.

5. The method of claim 1 , wherein the moving time window is a predetermined time window in a range from 1 second to 360 seconds and wherein the particular time interval is in a range from 1 millisecond to 5 seconds.

6. The method of claim 1 , wherein the selecting comprises:

converting the transmission power for the prior time interval to a used RF exposure for the prior time interval for each of the plurality of beams;

detecting an indication of the RF exposure for each of the plurality of beams;

scaling the used RF exposure for the prior time interval for each of the plurality of beams using the detected indication of the RF exposure for each of the plurality of beams;

adding the scaled RF exposure for the prior time interval for each of the plurality of beams to an accumulated RF exposure value for the time window for each of the plurality of beams to generate an accumulated sum for each of the plurality of beams;

calculating a maximum allowed transmission power for the particular time interval for each of the plurality of beams based on the accumulated sum for each of the plurality of beams and a maximum RF exposure limit; and

selecting the beam out of the plurality of the beams having the highest maximum allowed transmission power for the particular time interval as the beam for uplink transmission during the particular time interval.

7. The method of claim 1 , wherein the RF exposure comprises a specific absorption rate (SAR) or a power density (PD).

8. The method of claim 1 , wherein the plurality of beams comprises a plurality of combinations of antenna array elements of the UE and wherein the selecting comprises selecting one of the combinations of the antenna array elements for the uplink transmission.

9. An apparatus for wireless communication, comprising:

a processing system configured to select, from a plurality of beams, a beam for uplink transmission during a particular time interval, the selecting being based on a transmission power and a radio frequency (RF) exposure for each of the plurality of beams, wherein the particular time interval is part of a moving time window and wherein the processing system is configured to select the beam based on the transmission power of previous time intervals in the time window and the RF exposure, for each of the plurality of beams, for a prior time interval in the time window; and

a transmitter configured to transmit at least one uplink signal using the selected beam during the particular time interval.

10. The apparatus of claim 9 , wherein, for a subsequent interval after the particular time interval:

the processing system is configured to repeat the selection of the beam for uplink transmission during the subsequent time interval; and

the transmitter is configured to repeat the transmission of at least another uplink signal using the selected beam during the subsequent time interval.

11. The apparatus of claim 9 , wherein the plurality of beams comprises a plurality of antenna modules of the UE and wherein the processing system is configured to select the beam by at least selecting one of the plurality of antenna modules for the uplink transmission.

12. The apparatus of claim 9 , wherein the transmission power of the previous time intervals comprises an effective isotropic radiated power (EIRP) of the previous time intervals in the time window.

13. The apparatus of claim 9 , wherein the moving time window is a predetermined time window in a range from 1 second to 360 seconds and wherein the particular time interval is in a range from 1 millisecond to 5 seconds.

14. The apparatus of claim 9 , wherein the processing system is configured to select the beam by at least:

converting the transmission power for the prior time interval to a used RF exposure for the prior time interval for each of the plurality of beams;

detecting an indication of the RF exposure for each of the plurality of beams;

scaling the used RF exposure for the prior time interval for each of the plurality of beams using the detected indication of the RF exposure for each of the plurality of beams;

adding the scaled RF exposure for the prior time interval for each of the plurality of beams to an accumulated RF exposure value for the time window for each of the plurality of beams to generate an accumulated sum for each of the plurality of beams;

calculating a maximum allowed transmission power for the particular time interval for each of the plurality of beams based on the accumulated sum for each of the plurality of beams and a maximum RF exposure limit; and

selecting the beam out of the plurality of the beams having the highest maximum allowed transmission power for the particular time interval as the beam for uplink transmission during the particular time interval.

15. The apparatus of claim 9 , wherein the RF exposure comprises a specific absorption rate (SAR) or a power density (PD).

16. The apparatus of claim 9 , wherein the plurality of beams comprises a plurality of combinations of antenna array elements of the UE and wherein the processing system is configured to select the beam by at least selecting one of the combinations of the antenna array elements for the uplink transmission.

17. An apparatus for wireless communication, comprising:

means for selecting, from a plurality of beams, a beam for uplink transmission during a particular time interval, the selecting being based on a transmission power and a radio frequency (RF) exposure for each of the plurality of beams, wherein the particular time interval is part of a moving time window and wherein the means for selecting is configured to select the beam based on the transmission power of previous time intervals in the time window and the RF exposure, for each of the plurality of beams, for a prior time interval in the time window; and

means for transmitting at least one uplink signal using the selected beam during the particular time interval.

18. A non-transitory computer-readable medium having instructions stored thereon for:

selecting, from a plurality of beams, a beam for uplink transmission during a particular time interval, the selecting being based on a transmission power and a radio frequency (RF) exposure for each of the plurality of beams, wherein the particular time interval is part of a moving time window and wherein the selecting is based on the transmission power of previous time intervals in the time window and the RF exposure, for each of the plurality of beams, for a prior time interval in the time window; and

transmitting at least one uplink signal using the selected beam during the particular time interval.