Uplink access request in an OFDM communication environment

• US 20080013521A1
• Filed: 07/14/2006
• Published: 01/17/2008
• Est. Priority Date: 07/14/2006
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Li, Junyi, Rangan, Sundeep
• Granted Patent: US 7,869,421 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: H04L 5/003 Arrangements for allocating sub-channels of the transmission path
• CPC Class Codes: H04L 5/0078 Timing of allocation
• CPC Class Codes: H04L 5/0098 Signalling of the activation or deactivation of component carriers, subcarriers or frequency bands
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time

Abstract

The claimed subject matter relates to acquiring channel access in a wireless communication environment. A wireless terminal may transmit first and second sets of tones over respective first and second contiguous transmission periods. The first and second tone sets may be disjoint from each other and may each comprise a number of contiguous tones. The terminal may then refrain from transmitting during a third time period in order to receive a grant signal from a base station in response to the access request. The beginnings of the first time period and the second time period may be a function of a determined uplink transmission time.

Claims

1. A method of acquiring synchronization at a wireless terminal in a wireless communication environment, comprising:

receiving a downlink signal from a base station;

determining downlink signal timing information from the received signal;

determining an uplink transmission time for an access request signal as a function of the determined downlink timing information;

transmitting a first set of tones during a first time period; and

transmitting a second set of tones during a second time period, wherein the beginnings of the first time period and the second time period are a function of the determined uplink transmission time.

2. The method of claim 1, wherein the second time period follows immediately the first time period.

3. The method of claim 2, wherein the first and the second tone sets are disjoint.

4. The method of claim 1, wherein each of the first and second time periods has a duration of approximately two symbol periods.

5. The method of claim 1, wherein the first and the second tone sets are different.

6. The method of claim 2, wherein each of the first set of tones and the second set of tones comprises contiguous tones.

7. The method of claim 6, wherein the number of tones in each of the first and the second tone sets is between 8 and 32.

8. The method of claim 6, wherein the second set of tones is determined by the first set of tones according to a predetermined function.

9. The method of claim 8, further comprising refraining from transmitting a signal during a third time period, the third time period being immediately subsequent to the second time period.

10. The method of claim 9, wherein the third time period has a duration of at least 4 symbol periods.

11. The method of claim 9, further comprising receiving a response to the access request signal, the response including at least a timing correction command.

12. The method of claim 11, further comprising adjusting the uplink transmission time as a function of the timing correction command and transmitting the signal using the adjusted uplink transmission time.

13. An apparatus that facilitates synchronization of a wireless terminal to a base station, comprising:

a receiver that receives a downlink signal from a base station;

a processor that evaluates downlink signal timing information in the received signal and identifies an uplink transmission time for an access request signal as a function of the downlink timing information; and

a transmitter that transmits a first set of tones during a first time period and a second set of tones during a second time period, wherein the beginnings of the first time period and the second time period are a function of the determined uplink transmission time.

14. The apparatus of claim 13, wherein the second time period immediately follows the first time period.

15. The apparatus of claim 14, wherein the first and the second tone sets are disjoint.

16. The apparatus of claim 13, wherein each of the first and second time periods has a duration of approximately two symbol periods.

17. The apparatus of claim 13, wherein the first and the second tone sets are different.

18. The apparatus of claim 13, wherein the first set of tones comprises contiguous tones and the second set of tones comprises contiguous tones.

19. The apparatus of claim 18, wherein the number of tones in each of the first and the second tone sets is between 8 and 32.

20. The apparatus of claim 18, wherein the second set of tones is determined by the first set of tones according to a predetermined function.

21. The apparatus of claim 19, wherein the transmitter does not transmit a signal during a third time period, which is immediately subsequent to the second time period.

22. The apparatus of claim 21, wherein the third time period has a duration of at least 4 symbol periods.

23. The apparatus of claim 21, wherein the receiver listens for a response to the access request signal during the third time period, the response including at least a timing correction command.

24. The apparatus of claim 20, further comprising adjusting the uplink transmission time as a function of the timing correction command and transmitting the signal using the adjusted uplink transmission time.

25. An apparatus that facilitates synchronizing a wireless terminal in a wireless communication environment, comprising:

means for receiving a downlink signal from a base station;

means for determining downlink signal timing information from the received signal;

means for determining an uplink transmission time for an access request signal as a function of the determined downlink timing information;

means for transmitting a first set of tones during a first time period; and

means for transmitting a second set of tones during a second time period, wherein the beginnings of the first time period and the second time period are a function of the determined uplink transmission time.

26. The apparatus of claim 25, wherein the second time period follows immediately the first time period.

27. The apparatus of claim 26, wherein the first and the second tone sets are disjoint.

28. The apparatus of claim 25, wherein each of the first and second time periods has a duration of approximately two symbol periods.

29. The apparatus of claim 25, wherein the first and the second tone sets are different.

30. The apparatus of claim 26, wherein each of the first set of tones and the second set of tones comprises contiguous tones.

31. The apparatus of claim 30, wherein the number of tones in each of the first and the second tone sets is between 8 and 32.

32. The apparatus of claim 30, wherein the second set of tones is determined by the first set of tones according to a predetermined function.

33. The apparatus of claim 32, wherein the means for transmitting refrains from transmitting a signal during a third time period, the third time period being immediately subsequent to the second time period.

34. The apparatus of claim 33, wherein the third time period has a duration of at least 4 symbol periods.

35. The apparatus of claim 33, wherein the means for receiving receives a response to the access request signal, the response including at least a timing correction command.

36. The apparatus of claim 35, further comprising means for adjusting the uplink transmission time as a function of the timing correction command and transmitting the signal using the adjusted uplink transmission time.

37. A computer-readable medium having stored thereon computer-readable instructions, the instructions comprising:

receiving a downlink signal from a base station;

determining downlink signal timing information from the received signal;

determining an uplink transmission time for an access request signal as a function of the determined downlink timing information;

transmitting a first set of tones during a first time period; and

transmitting a second set of tones during a second time period, wherein the beginnings of the first time period and the second time period are a function of the determined uplink transmission time.

38. The computer-readable medium of claim 37, wherein the second time period follows immediately the first time period.

39. The computer-readable medium of claim 38, wherein the first and the second tone sets are disjoint.

40. The computer-readable medium of claim 37, wherein each of the first and second time periods has a duration of approximately two symbol periods.

41. The computer-readable medium of claim 37, wherein the first and the second tone sets are different.

42. The computer-readable medium of claim 38, wherein each of the first set of tones and the second set of tones comprises contiguous tones.

43. The computer-readable medium of claim 42, wherein each of the first and the second tone sets has a number of tones ranging from 8 to 32 tones.

44. The computer-readable medium of claim 42, further comprising instructions for determining the second set of tones based on the first set of tones according to a predetermined function.

45. The computer-readable medium of claim 44, further comprising instructions for refraining from transmitting a signal during a third time period, the third time period being immediately subsequent to the second time period.

46. The computer-readable medium of claim 45, wherein the third time period has a duration of at least 4 symbol periods.

47. The computer-readable medium of claim 45, further comprising instructions for receiving a response to the access request signal, the response including at least a timing correction command.

48. The computer-readable medium of claim 47, further comprising instructions for adjusting the uplink transmission time as a function of the timing correction command and transmitting the signal using the adjusted uplink transmission time.

49. A processor that executes instructions for requesting channel access in a wireless communication environment, the instructions comprising:

receiving a downlink signal from a base station;

determining downlink signal timing information from the received signal;

determining an uplink transmission time for an access request signal as a function of the determined downlink timing information;

transmitting a first set of tones during a first time period; and

transmitting a second set of tones during a second time period, wherein the beginnings of the first time period and the second time period are a function of the determined uplink transmission time.

50. The processor of claim 49, wherein the second time period is immediately subsequent to the first time period.

51. The processor of claim 50, wherein the first and the second tone sets are disjoint.

52. The processor of claim 49, wherein each of the first and second time periods has a duration of approximately two symbol periods.

53. The processor of claim 49 wherein the first and the second tone sets are different.

54. The processor of claim 50, wherein each of the first set of tones and the second set of tones comprises contiguous tones.

55. The processor of claim 54, wherein each of the first and the second tone sets has a number of tones ranging from 8 to 32 tones.

56. The processor of claim 54, further comprising instructions for determining the second set of tones based on the first set of tones according to a predetermined function.

57. The processor of claim 56, further comprising instructions for refraining from transmitting a signal during a third time period, the third time period being immediately subsequent to the second time period.

58. The processor of claim 57, wherein the third time period has a duration of at least 4 symbol periods.

59. The processor of claim 57, further comprising instructions for receiving a response to the access request signal, the response including at least a timing correction command.

60. The processor of claim 59, further comprising instructions for adjusting the uplink transmission time as a function of the timing correction command and transmitting the signal using the adjusted uplink transmission time.

61. A method of providing channel access to a wireless terminal in a wireless communication environment, comprising:

receiving a first and second sets of tones during a channel acquisition time period;

performing a fast-Fourier transform protocol on each received tone set to demodulate a complete access request waveform for each tone set; and

transmitting a signal granting access to one or more requested channels.

62. The method of claim 61, further comprising performing the FFT protocol during a first five symbols of the channel acquisition time period and transmitting the signal granting access during a last four symbols of the acquisition time period.