LTE-U CLEAR CHANNEL ASSESSMENT OPERATIONS

• US 20150099525A1
• Filed: 10/06/2014
• Published: 04/09/2015
• Est. Priority Date: 10/07/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Ji, Tingfang, Bhushan, Naga, Wei, Yongbin, Gaal, Peter, Luo, Tao, Chen, Wanshi, Malladi, Durga Prasad, Damnjanovic, Aleksandar, Somasundaram, Kiran Kumar, Xu, Hao
• Granted Patent: US 9,763,225 B2
• Time in Patent Office: Days
• US Class Current: 455/450
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 56/0045 compensating for timing error by altering transmission time
• CPC Class Codes: H04W 72/04 Wireless resource allocation
• CPC Class Codes: H04W 72/1215 for collaboration of different radio technologies
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

The subject technology provides for performing clear channel assessment (CCA) in LTE-U. Transmissions may be monitored in a resource reserved for CCA. An energy of the transmissions is detected over a shorter duration than an assigned slot in the resource reserved for CCA. A beacon may be transmitted in a slot assigned to a wireless entity for CCA in response to detecting a clear channel based on the monitoring. In another aspect, a beacon transmission for CCA and a timing for the monitoring are adapted in response to detecting the transmissions for a consecutive number of CCA periods. Further, the subject technology provides for adjusting to a maximum power for transmission of a beacon in a slot assigned to a mobile station for CCA in response to detecting a clear channel based on the monitoring.

Claims

1. A method for performing clear channel assessment (CCA) in LTE-U, the method comprising:

monitoring for transmissions in a resource reserved for CCA; and

detecting an energy of the transmissions over a shorter duration than an assigned slot in the resource reserved for CCA.

2. The method of claim 1, wherein the shorter duration is based on at least one guard period at the edges of the assigned slot.

3. The method of claim 1, further comprising:

transmitting a beacon in a slot assigned to a wireless entity for CCA in response to detecting a clear channel based on the monitoring.

4. The method of claim 1, wherein the transmissions follow a timing mask having an off time period with a first predetermined time offset before an orthogonal frequency division multiplexing (OFDM) symbol boundary, and an on period with a second predetermined time offset after the OFDM symbol boundary.

5. The method of claim 1, further comprising:

adapting a beacon transmission for CCA and a timing for the monitoring in response to detecting the transmissions for a consecutive number of CCA periods.

6. The method of claim 5, wherein adapting the beacon transmission comprises transmitting the beacon in an auxiliary resource reserved for CCA.

7. The method of claim 5, further comprising:

biasing timing for detected transmissions to determine blocking by intra-PLMN nodes.

8. The method of claim 1, further comprising:

adjusting to a maximum power for transmission of a beacon in a slot assigned to a mobile station for CCA in response to detecting a clear channel based on the monitoring.

9. An apparatus for performing clear channel assessment (CCA) in LTE-U, the apparatus comprising:

means for monitoring for transmissions in a resource reserved for CCA; and

means for detecting an energy of the transmissions over a shorter duration than an assigned slot in the resource reserved for CCA.

10. The apparatus of claim 9, wherein the shorter duration is based on at least one guard period at the edges of the assigned slot.

11. The apparatus of claim 9, further comprising:

means for transmitting a beacon in a slot assigned to a wireless entity for CCA in response to detecting a clear channel based on the monitoring,

12. The apparatus of claim 9, wherein the transmissions follow a timing mask having an off time period with a first predetermined time offset before an orthogonal frequency division multiplexing (OFDM) symbol boundary, and an on period with a second predetermined time offset after the OFDM symbol boundary.

13. The apparatus of claim 9, further comprising:

means for adapting a beacon transmission for CCA and a timing for the monitoring in response to detecting the transmissions for a consecutive number of CCA periods.

14. The apparatus of claim 13, wherein adapting the beacon transmission comprises transmitting the beacon in an auxiliary resource reserved for CCA.

15. The apparatus of claim 13, further comprising:

means for biasing timing for detected transmissions to determine blocking by intra-PLMN nodes.

16. The apparatus of claim 9, further comprising:

means for adjusting to a maximum power for transmission of a beacon in a slot assigned to a mobile station for CCA in response to detecting a clear channel based on the monitoring.

17. An apparatus for performing clear channel assessment (CCA) in LTE-U, the apparatus comprising:

at least one transceiver configured for monitoring transmissions in a resource reserved for CCA;

at least one processor configured for detecting an energy of the transmissions over a shorter duration than an assigned slot in the resource reserved for CCA; and

a memory coupled to the at least one processor for storing data.

18. The apparatus of claim 17, wherein the shorter duration is based on at least one guard period at the edges of the assigned slot.

19. The apparatus of claim 17, wherein the transmissions follow a timing mask having an off time period with a first predetermined time offset before an orthogonal frequency division multiplexing (OFDM) symbol boundary, and an on period with a second predetermined time offset after the OFDM symbol boundary.

20. The apparatus of claim 17, wherein the at least one transceiver is further configured for transmitting a beacon in a slot assigned to a wireless entity for CCA in response to detecting a clear channel based on the monitoring.

21. The apparatus of claim 17, wherein the at least one processor is further configured for adapting a beacon transmission for CCA and a timing for the monitoring in response to detecting the transmissions for a consecutive number of CCA periods.

22. The apparatus of claim 21, wherein adapting the beacon transmission comprises transmitting the beacon in an auxiliary resource reserved for CCA.

23. The apparatus of claim 21, means the at least one processor is further configured for biasing timing for detected transmissions to determine blocking by intra-PLMN nodes

24. The apparatus of claim 17, wherein the at least one processor is further configured for adjusting to a maximum power for transmission of a beacon in a slot assigned to a mobile station for CCA in response to detecting a clear channel based on the monitoring.

25. A computer program product comprising:

computer-readable medium storing code for causing at least one computer to;

monitor transmissions in a resource reserved for clear channel assessment (CCA);

detect an energy of the transmissions over a shorter duration than an assigned slot in the resource reserved for CCA.

26. The computer program product of claim 25, wherein the shorter duration is based on at least one guard period at the edges of the assigned slot.

27. The computer program product of claim 25, wherein the transmissions follow a timing mask having an off time period with a first predetermined time offset before an orthogonal frequency division multiplexing (OFDM) symbol boundary, and an on period with a second predetermined time offset after the OFDM symbol boundary.

28. The computer program product of claim 25, wherein the computer-readable medium further stores code for causing the at least one computer to:

transmit a beacon in a slot assigned to a wireless entity for CCA in response to detecting a clear channel based on the monitoring.

29. The computer program product of claim 25, wherein the computer-readable medium further stores code for causing the at least one computer to:

adapt a beacon transmission for CCA and a timing for the monitoring in response to detecting the transmissions for a consecutive number of CCA periods based on the monitoring.

30. The computer program product of claim 29, wherein adapting the beacon transmission comprises transmitting the beacon transmission in an auxiliary resource reserved for CCA.

31. The computer program product of claim 25, wherein the computer-readable medium further stores code for causing the at least one computer to:

bias timing for detected transmissions to determine blocking by intra-PLMN nodes.

32. The computer program product of claim 25, wherein the computer-readable medium further stores code for causing the at least one computer to:

adjust to a maximum power for transmission of a beacon in a slot assigned to a mobile station for CCA in response to detecting a clear channel based on the monitoring.

33. A method for an access point performing timing advance in LTE-U, the method comprising:

receiving, from at least one mobile station, at least one message comprising timing information from the at least one mobile station; and

determining, using the received timing information, at least one timing advance parameter for channel usage beacon signals (CUBS) transmission and an associated clear channel assessment (CCA) window for the at least one mobile station based on reducing a timing difference between the at least mobile station.

34. The method of claim 33, wherein the receiving comprises at least one of receiving a random access preamble or receiving at least one Rx-Tx timing difference report comprising the timing information.

35. The method of claim 33, wherein the transmit timing of CUBS is different from the transmit timing of PUSCH, the method further comprising:

transmitting at least two timing advance commands to a same mobile station.

36. The method of claim 33, wherein the transmit timing of CUBS is the same as a transmit timing from a PUSCH.

37. The method of claim 33, further comprising:

performing, at the access point, uplink power control for a mobile station that needs to perform CCA in LTE-U, the performing comprising;

determining a target received power for CUBS transmissions based on a CCA power threshold and a power margin based on mobile stations of neighboring access points;

determining a slope of a transmission power as a function of an estimated path loss for CUBS transmission; and

sending the determined target received power and the determined slope to the mobile station.

38. The method of claim 37, wherein the power margin is further based on an antenna gain different plus a path loss difference.

39. The method of claim 37, wherein the slope is determined such that CUBS transmissions have a similar power level for mobile stations with small path losses and with large path losses.

40. The method of claim 37, wherein the slope is determined such that CUBS transmissions have higher power for mobile stations with smaller path losses.

41. An apparatus for performing timing advance in LTE-U, the apparatus comprising:

means for receiving, from at least one mobile station, at least one message comprising timing information from the at least one mobile station; and

means for determining, using the received timing information, at least one timing advance parameter for channel usage beacon signals (CUBS) transmission and an associated CCA window for the at least one mobile station based on reducing a timing difference between the at least mobile station.

42. The apparatus of claim 41, further comprising:

means for performing uplink power control for a mobile station that needs to perform clear channel assessment CCA in LTE-U, the means for performing comprising;

means for determining a target received power for CUBS transmissions based on a CCA power threshold and a power margin based on mobile stations of neighboring access points;

means for determining a slope of a transmission power as a function of an estimated path loss for CUBS transmission; and

means for sending the determined target received power and the determined slope to the mobile station.

43. An apparatus for performing timing advance in LTE-U, the apparatus comprising:

at least one transceiver configured for receiving, from at least one mobile station, at least one message comprising timing information from the at least one mobile station;

at least one processor configured for determining, using the received timing information, at least one timing advance parameter for channel usage beacon signals (CUBS) transmission and an associated CCA window for the at least one mobile station based on reducing a timing difference between the at least mobile station; and

a memory coupled to the at least one processor for storing data.

44. The apparatus of claim 43, wherein the at least one processor is further configured for performing uplink power control for a mobile station that needs to perform clear channel assessment CCA in LTE-U, the performing comprising:

determining a target received power for CUBS transmissions based on a CCA power threshold and a power margin based on mobile stations of neighboring access points, determining a slope of a transmission power as a function of an estimated path loss for CUBS transmission.

45. The apparatus of claim 44, wherein the at least one transceiver is further configured for sending the determined target received power and the determined slope to the mobile station.

46. A computer program product comprising:

computer-readable medium storing code for causing at least one computer to;

receive, from at least one mobile station, at least one message comprising timing information from the at least one mobile station; and

determine, using the received timing information, at least one timing advance parameter for channel usage beacon signals (CUBS) transmission and an associated CCA window for the at least one mobile station based on reducing a timing difference between the at least mobile station.

47. The computer program product of claim 46, wherein the computer-readable medium further stores code for causing the at least one computer to:

determine a target received power for CUBS transmissions based on a CCA power threshold and a power margin based on mobile stations of neighboring access points;

determine a slope of a transmission power as a function of an estimated path loss for CUBS transmission; and

send the determined target received power and the determined slope to the mobile station.