Aperiodic sounding reference signal transmission method and apparatus

1. A method for wireless communication, comprising:

receiving a first downlink control message, wherein the first downlink control message is created by modifying a portion of a second downlink control message, wherein the second downlink control message does not trigger an aperiodic sounding reference signal (SRS) transmission and wherein the first downlink control message indicates resources allocated to the aperiodic SRS transmission; and

transmitting an aperiodic SRS based on the received first downlink control message.

2. The method of claim 1 , wherein the receiving comprises receiving the first downlink control message in a random access response message.

3. The method of claim 1 , wherein the portion of the second downlink control message comprises one of a one bit field and a two bit field.

4. The method of claim 1 , wherein the transmitting comprises transmitting the aperiodic SRS after a pre-determined time period after receiving the first downlink control message.

5. The method of claim 4 , wherein the pre-determined time period is at least 4 milliseconds.

6. The method of claim 1 , wherein the portion of the second downlink control message comprises an addition of a one bit field to create the first downlink control message.

7. The method of claim 6 , wherein the resources allocated to the aperiodic SRS transmission are associated with the one bit field and are configured by higher layer.

8. An apparatus for wireless communication, comprising:

means for receiving a first downlink control message, wherein the first downlink control message is created by modifying a portion of a second downlink control message, wherein the second downlink control message does not trigger an aperiodic sounding reference signal (SRS) transmission and wherein the first downlink control message indicates resources allocated to the aperiodic SRS transmission;

means for transmitting an aperiodic SRS based on the received first downlink control message.

9. The apparatus of claim 8 , wherein the means for receiving comprises means for receiving the first downlink control message in a random access response message.

10. The apparatus of claim 8 , wherein the portion of the second downlink control message comprises one of a one bit field and a two bit field.

11. The apparatus of claim 8 , wherein the means for transmitting comprises means for transmitting the aperiodic SRS after a pre-determined time period after receiving the first downlink control message.

12. The apparatus of claim 11 , wherein the pre-determined time period is at least 4 milliseconds.

13. The apparatus of claim 8 , wherein the portion of the second downlink control message comprises an addition of a one bit field to create the first downlink control message.

14. The apparatus of claim 13 , wherein the resources allocated to the aperiodic SRS transmission are associated with the one bit field and are configured by higher layer.

15. An apparatus for wireless communication, comprising:

a processor configured to:

receive a first downlink control message, wherein the first downlink control message is created by modifying a portion of a second downlink control message, wherein the second downlink control message does not trigger an aperiodic sounding reference signal (SRS) transmission and wherein the first downlink control message indicates resources allocated to the aperiodic SRS transmission; and

transmit an aperiodic SRS based on the received first downlink control message; and

memory coupled to the processor.

16. The apparatus of claim 15 , wherein the processor is further configured to receive the first downlink control message in a random access response message.

17. The apparatus of claim 15 , wherein the portion of the second downlink control message comprises one of a one bit field and a two bit field.

18. The apparatus of claim 15 , wherein the processor is further configured to transmit the aperiodic SRS after a pre-determined time period after receiving the first downlink control message.

19. The apparatus of claim 18 , wherein the pre-determined time period is at least 4 milliseconds.

20. The apparatus of claim 15 , wherein the portion of the second downlink control message comprises an addition of a one bit field to create the first downlink control message.

21. The apparatus of claim 20 , wherein the resources allocated to the aperiodic SRS transmission are associated with the one bit field and are configured by higher layer.

22. A computer program product comprising a non-transitory computer-readable storage medium, the non-transitory computer-readable storage medium comprising:

instructions for causing a computer to receive a first downlink control message, wherein the first downlink control message is created by modifying a portion of a second downlink control message, wherein the second downlink control message does not trigger an aperiodic sounding reference signal (SRS) transmission and wherein the first downlink control message indicates resources allocated to the aperiodic SRS transmission; and

instructions for causing the computer to transmit an aperiodic SRS based on the received first downlink control message.

23. The computer program product of claim 22 , wherein the non-transitory computer-readable storage medium further comprises instructions for causing the computer to receive the first downlink control message in a random access response message.

24. The computer program product of claim 22 , wherein the portion of the second downlink control message comprises one of a one bit field and a two bit field.

25. The computer program product of claim 22 , wherein the non-transitory computer-readable storage medium further comprises instructions for causing the computer to transmit the aperiodic SRS after a pre-determined time period after receiving the first downlink control message.

26. The computer program product of claim 25 , wherein the pre-determined time period is at least 4 milliseconds.

27. The computer program product of claim 22 , wherein the portion of the second downlink control message comprises an addition of a one bit field to create the first downlink control message.

28. The computer program product of claim 27 , wherein the resources allocated to the aperiodic SRS transmission are associated with the one bit field and are configured by higher layer.