COLLISION AVOIDANCE SCHEME FOR WIRELESS COMMUNICATIONS OVER UNLICENSED SPECTRUM

• US 20140341135A1
• Filed: 05/19/2014
• Published: 11/20/2014
• Est. Priority Date: 05/20/2013
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Bhushan, Naga, Wei, Yongbin, Gaal, Peter, Luo, Tao, Ji, Tingfang, Horn, Gavin Bernard, Chen, Wanshi, Damnjanovic, Aleksandar, Malladi, Durga Prasad
• Granted Patent: US 9,717,098 B2
• Time in Patent Office: Days
• US Class Current: 370/329
• CPC Class Codes: H04J 11/00 Orthogonal multiplex systems, e.g. using WALSH codesH04J13/00 takes precedence
• CPC Class Codes: H04L 1/00 Arrangements for detecting or preventing errors in the information received correcting synchronisation H04L7/00
• CPC Class Codes: H04L 1/0003 by switching between different modulation schemes
• CPC Class Codes: H04L 1/0009 by adapting the channel coding H04L1/1812 takes precedence
• CPC Class Codes: H04L 1/0026 Transmission of channel quality indication
• CPC Class Codes: H04L 1/003 Adaptive formatting arrangements particular to signalling, e.g. variable amount of bits
• CPC Class Codes: H04L 1/009 arrangements specific to transmitters
• CPC Class Codes: H04L 1/0612 Space-time modulation
• CPC Class Codes: H04L 27/0006 Assessment of spectral gaps suitable for allocating digitally modulated signals, e.g. for carrier allocation in cognitive radio for spectrum sharing between different networks H04W16/14
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2603 Signal structure ensuring backward compatibility with legacy system
• CPC Class Codes: H04L 5/001 the frequencies being arranged in component carriers
• CPC Class Codes: H04L 5/0044 allocation of payload
• CPC Class Codes: H04L 5/005 of common pilots, i.e. pilots destined for multiple users or terminals
• CPC Class Codes: H04L 5/0053 Allocation of signaling, i.e. of overhead other than pilot signals
• CPC Class Codes: H04L 5/14 Two-way operation using the same type of signal, i.e. duplex
• CPC Class Codes: H04L 5/1469 using time-sharing
• CPC Class Codes: H04W 16/14 Spectrum sharing arrangements between different networks
• CPC Class Codes: H04W 24/02 Arrangements for optimising operational condition
• CPC Class Codes: H04W 28/0252 per individual bearer or channel dynamic wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 28/0289 : Congestion control load shedding arrangements in network planning H04W16/08; performing reselection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 28/08 : Load balancing or load distribution transferring a connection for handling the traffic H04W36/22; wireless traffic scheduling H04W72/12
• CPC Class Codes: H04W 28/16 : Central resource management; Negotiation of resources or communication parameters, e.g. negotiating bandwidth or QoS [Quality of Service]
• CPC Class Codes: H04W 48/10 : using broadcasted information
• CPC Class Codes: H04W 56/001 : Synchronization between nodes
• CPC Class Codes: H04W 56/0015 : one node acting as a reference for the others
• CPC Class Codes: H04W 56/002 : Mutual synchronization
• CPC Class Codes: H04W 72/04 : Wireless resource allocation
• CPC Class Codes: H04W 72/12 : Wireless traffic scheduling
• CPC Class Codes: H04W 72/21 : in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/541 : using the level of interference
• CPC Class Codes: H04W 74/006 : in the downlink, i.e. towards the terminal
• CPC Class Codes: H04W 74/04 : Scheduled access hybrid access H04W74/02
• CPC Class Codes: H04W 74/0808 : using carrier sensing, e.g. carrier sense multiple access [CSMA]
• CPC Class Codes: H04W 74/0816 : with collision avoidance
• CPC Class Codes: H04W 74/0833 : Random access procedures, e.g. with 4-step access
• CPC Class Codes: H04W 76/15 : Setup of multiple wireless link connections
• CPC Class Codes: H04W 84/12 : WLAN [Wireless Local Area Networks]
• CPC Class Codes: H04W 88/02 : Terminal devices
• CPC Class Codes: H04W 88/06 : adapted for operation in multiple networks or having at least two operational modes, e.g. multi-mode terminals
• CPC Class Codes: H04W 88/08 : Access point devices

Abstract

Methods and apparatuses are described in which an unlicensed spectrum is used for Long Term Evolution (LTE) communications. A first method includes performing clear channel assessment (CCA) to determine availability of an unlicensed spectrum, transmitting a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available, and receiving, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal. A second method includes transmitting an RTS signal in an unlicensed spectrum or a V-RTS signal in a licensed spectrum, addressed to a set of UEs, and transmitting a CTS-to-self signal in the unlicensed spectrum along with the transmission of the V-RTS signal.

Claims

1. A method for wireless communications, comprising:

performing clear channel assessment (CCA) to determine availability of an unlicensed spectrum;

transmitting a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receiving, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal.

2. The method of claim 1, wherein transmitting the RTS signal comprises:

transmitting the RTS signal prior to an uplink grant to protect a subsequent uplink transmission over the unlicensed spectrum from the set of UEs.

3. The method of claim 1, wherein the RTS signal comprises a Media Access Control Identifier (MAC ID) of a source of the RTS signal.

4. The method of claim 3, wherein the MAC ID of the source comprises a 48-bit MAC ID.

5. The method of claim 1, wherein the RTS signal comprises a hashed version of the MAC ID of the UEs in the set.

6. The method of claim 1, wherein the common CTS signal is received a short inter-frame space (SIFS) after the transmission of the RTS signal, the common CTS signal comprising a MAC ID of a source of the RTS signal.

7. The method of claim 1, wherein each individual CTS comprises a MAC ID of a source of the RTS signal and a MAC ID of the UE transmitting the individual CTS.

8. The method of claim 1, wherein the individual CTS signals for the UEs in the set are received at staggered times.

9. The method of claim 1, wherein:

the CCA is performed during a subframe in a current gating interval;

the RTS signal is transmitted after the CCA; and

the common CTS signal and the individual CTS signals are received before an end of the subframe.

10. The method of claim 9, wherein a time associated with the CCA and a time associated with the subsequent transmission of the RTS signal are randomly staggered among different eNBs to avoid collisions at devices receiving the RTS signal.

11. The method of claim 9, wherein a time associated with the CCA and a time associated with the subsequent transmission of the RTS signal are mutually staggered to avoid collisions at devices receiving the RTS signal, the staggering being based at least on coordination signaling exchanged between eNBs.

12. An apparatus for wireless communications, comprising:

means for performing clear channel assessment (CCA) to determine availability of an unlicensed spectrum;

means for transmitting a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

means for receiving, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal.

13. The apparatus of claim 12, wherein the means for transmitting the RTS signal comprises:

means for transmitting the RTS signal prior to an uplink grant to protect a subsequent uplink transmission over the unlicensed spectrum from the set of UEs.

14. The apparatus of claim 12, wherein the RTS signal comprises a Media Access Control Identifier (MAC ID) of a source of the RTS signal.

15. The apparatus of claim 14, wherein the MAC ID of the source comprises a 48-bit MAC ID.

16. The apparatus of claim 12, wherein the RTS signal comprises a hashed version of the MAC ID of the UEs in the set.

17. The apparatus of claim 12, wherein the common CTS signal is received a short inter-frame space (SIFS) after the transmission of the RTS signal, the common CTS signal comprising a MAC ID of a source of the RTS signal.

18. The apparatus of claim 12, wherein each individual CTS comprises a MAC ID of a source of the RTS signal and a MAC ID of the UE transmitting the individual CTS.

19. The apparatus of claim 12, wherein the individual CTS signals for the UEs in the set are received at staggered times.

20. The apparatus of claim 12, wherein:

the CCA is performed during a subframe in a current gating interval;

the RTS signal is transmitted after the CCA; and

the common CTS signal and the individual CTS signals are received before an end of the subframe.

21. The apparatus of claim 20, wherein a time associated with the CCA and a time associated with the subsequent transmission of the RTS signal are randomly staggered among different eNBs to avoid collisions at devices receiving the RTS signal.

22. The apparatus of claim 20, wherein a time associated with the CCA and a time associated with the subsequent transmission of the RTS signal are mutually staggered to avoid collisions at devices receiving the RTS signal, the staggering being based at least on coordination signaling exchanged between eNBs.

24. The apparatus of claim 22, wherein the instructions executable by the processor to transmit the RTS signal comprise instructions executable by the processor to:

transmit the RTS signal prior to an uplink grant to protect a subsequent uplink transmission over the unlicensed spectrum from the set of UEs.

25. The apparatus of claim 22, wherein the individual CTS signals for the UEs in the set are received at staggered times.

26. The apparatus of claim 22, wherein:

the CCA is performed during a subframe in a current gating interval;

the RTS signal is transmitted after the CCA; and

the common CTS signal and the individual CTS signals are received before an end of the subframe.

27. The apparatus of claim 26, wherein a time associated with the CCA and a time associated with the subsequent transmission of the RTS signal are randomly staggered among different eNBs to avoid collisions at devices receiving the RTS signal.

28. The apparatus of claim 26, wherein a time associated with the CCA and a time associated with the subsequent transmission of the RTS signal are mutually staggered to avoid collisions at devices receiving the RTS signal, the staggering being based at least on coordination signaling exchanged between eNBs.

23. An apparatus for wireless communications, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

perform clear channel assessment (CCA) to determine availability of an unlicensed spectrum;

transmit a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receive, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal.

29. A computer program product for communications by a wireless communications apparatus in a wireless communications system, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to cause the wireless communications apparatus to:

perform clear channel assessment (CCA) to determine availability of an unlicensed spectrum;

transmit a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receive, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal.

30. A method for wireless communications, comprising:

receiving, at a user equipment (UE), a request-to-send (RTS) signal transmitted to a set of UEs over an unlicensed spectrum; and

transmitting, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal in response to the RTS signal.

31. The method of claim 30, wherein receiving the RTS signal comprises:

receiving the RTS signal prior to an uplink grant to protect a subsequent uplink transmission over the unlicensed spectrum from the set of UEs.

32. The method of claim 30, wherein the RTS signal comprises a Media Access Control Identifier (MAC ID) of a source of the RTS signal.

33. The method of claim 32, wherein the MAC ID of the source comprises a 48-bit MAC ID.

34. The method of claim 30, wherein the RTS signal comprises a hashed version of a MAC ID of the UE.

35. The method of claim 30, wherein the common CTS signal is transmitted a short inter-frame space (SIFS) after the reception of the RTS signal, the common CTS signal comprising a MAC ID of a source of the RTS signal.

36. The method of claim 30, wherein the individual CTS comprises a MAC ID of a source of the RTS signal and a MAC ID of the UE.

37. The method of claim 30, wherein the individual CTS signal is transmitted at a staggered time with respect to another individual CTS signal transmitted by another UE in the set of UEs.

38. The method of claim 30, wherein:

the RTS signal is received during a subframe; and

the common CTS signal and the individual CTS signals are transmitted before an end of the subframe.

39. An apparatus for wireless communications, comprising:

means for receiving, at a user equipment (UE), a request-to-send (RTS) signal transmitted to a set of UEs over an unlicensed spectrum; and

means for transmitting, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal in response to the RTS signal.

40. The apparatus of claim 39, wherein the means for receiving the RTS signal comprises:

means for receiving the RTS signal prior to an uplink grant to protect a subsequent uplink transmission over the unlicensed spectrum from the set of UEs.

41. The apparatus of claim 39, wherein the RTS signal comprises a Media Access Control Identifier (MAC ID) of a source of the RTS signal.

42. The apparatus of claim 41, wherein the MAC ID of the source comprises a 48-bit MAC ID.

43. The apparatus of claim 39, wherein the RTS signal comprises a hashed version of a MAC ID of the UE.

44. The apparatus of claim 39, wherein the common CTS signal is transmitted a short inter-frame space (SIFS) after the reception of the RTS signal, the common CTS signal comprising a MAC ID of a source of the RTS signal.

45. The apparatus of claim 39, wherein the individual CTS comprises a MAC ID of a source of the RTS signal and a MAC ID of the UE.

46. The apparatus of claim 39, wherein the individual CTS signal is transmitted at a staggered time with respect to another individual CTS signal transmitted by another UE in the set of UEs.

47. The apparatus of claim 39, wherein:

the RTS signal is received during a subframe; and

the common CTS signal and the individual CTS signals are transmitted before an end of the subframe.

48. An apparatus for wireless communications, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

receive, at a user equipment (UE), a request-to-send (RTS) signal transmitted to a set of UEs over an unlicensed spectrum; and

transmit, in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal in response to the RTS signal.

49. The apparatus of claim 48, wherein the instructions executable by the processor to receive the RTS signal comprise instructions executable by the processor to:

receive the RTS signal prior to an uplink grant to protect a subsequent uplink transmission over the unlicensed spectrum from the set of UEs.

50. The apparatus of claim 48, wherein the individual CTS comprises a MAC ID of a source of the RTS signal and a MAC ID of the UE.

51. The apparatus of claim 48, wherein the individual CTS signal is transmitted at a staggered time with respect to another individual CTS signal transmitted by another UE in the set of UEs.

52. The apparatus of claim 48, wherein:

the RTS signal is received during a subframe; and

the common CTS signal and the individual CTS signals are transmitted before an end of the subframe.

53. A computer program product for communications by a user equipment (UE) in a wireless communications system, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to cause the UE to:

perform clear channel assessment (CCA) to determine availability of an unlicensed spectrum;

transmit a request-to-send (RTS) signal to a set of user equipments (UEs) using the unlicensed spectrum when a determination is made that the unlicensed spectrum is available; and

receive in the unlicensed spectrum, a common clear-to-send (CTS) signal and an individual CTS signal from one or more of the UEs in response to the RTS signal.

54. A method for wireless communications, comprising:

transmitting a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) signal in a licensed spectrum, addressed to a set of user equipments (UEs); and

transmitting a clear-to-send (CTS)-to-self signal in the unlicensed spectrum along with the transmission of the V-RTS signal.

55. The method of claim 54, further comprising:

receiving in the licensed spectrum a virtual CTS (V-CTS) signal from each UE in the set, in response to the RTS signal or to the V-RTS signal.

56. The method of claim 55, wherein the V-CTS signal comprises measurements made by the respective UE for use in future scheduling.

57. The method of claim 55, further comprising:

scheduling, after receiving the V-CTS signal, traffic based on current channel knowledge for a remainder of a subframe.

58. The method of claim 54, wherein the RTS signal is transmitted in the downlink primary component carrier for each UE in the set of UEs.

59. An apparatus for wireless communications, comprising:

means for transmitting a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) signal in a licensed spectrum, addressed to a set of user equipments (UEs); and

means for transmitting a clear-to-send (CTS)-to-self signal in the unlicensed spectrum along with the transmission of the V-RTS signal.

60. The apparatus of claim 59, further comprising:

means for receiving in the licensed spectrum a virtual CTS (V-CTS) signal from each UE in the set, in response to the RTS signal or to the V-RTS signal.

61. The apparatus of claim 60, wherein the V-CTS signal comprises measurements made by the respective UE for use in future scheduling.

62. The apparatus of claim 60, further comprising:

means for scheduling, after receiving the V-CTS signal, traffic based on current channel knowledge for a remainder of a subframe.

63. The apparatus of claim 59, wherein the RTS signal is transmitted in the downlink primary component carrier for each UE in the set of UEs.

64. An apparatus for wireless communications, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

transmit a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) signal in a licensed spectrum, addressed to a set of user equipments (UEs); and

transmit a clear-to-send (CTS)-to-self signal in the unlicensed spectrum along with the transmission of the V-RTS signal.

65. The apparatus of claim 64, wherein the instructions are executable by the processor to:

receive in the licensed spectrum a virtual CTS (V-CTS) signal from each UE in the set, in response to the RTS signal or to the V-RTS signal.

66. The apparatus of claim 65, wherein the V-CTS signal comprises measurements made by the respective UE for use in future scheduling.

67. The apparatus of claim 65, wherein the instructions are executable by the processor to:

schedule, after receiving the V-CTS signal, traffic based on current channel knowledge for a remainder of a subframe.

68. A computer program product for communications by a wireless communications apparatus in a wireless communications system, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to cause the wireless communications apparatus to:

transmit a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) signal in a licensed spectrum, addressed to a set of user equipments (UEs); and

transmit a clear-to-send (CTS)-to-self signal in the unlicensed spectrum along with the transmission of the V-RTS signal.

69. A method for wireless communications, comprising:

receiving, at a user equipment (UE), a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) in a licensed spectrum, the RTS signal or the V-RTS signal being addressed to a set of UEs.

70. The method of claim 69, further comprising:

transmitting in the licensed spectrum a virtual CTS (V-CTS) signal from the UE, in response to the RTS signal or to the V-RTS signal.

71. The method of claim 70, wherein the V-CTS signal comprises measurements made by the UE for use in future scheduling.

72. The method of claim 69, wherein the RTS signal is received in the downlink primary component carrier of the UE.

73. An apparatus for wireless communications, comprising:

means for receiving, at a user equipment (UE), a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) in a licensed spectrum, the RTS signal or the V-RTS signal being addressed to a set of UEs.

74. An apparatus for wireless communications, comprising:

a processor;

memory in electronic communication with the processor; and

instructions stored in the memory, the instructions being executable by the processor to;

receive, at a user equipment (UE), a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) in a licensed spectrum, the RTS signal or the V-RTS signal being addressed to a set of UEs.

75. A computer program product for communications by a UE in a wireless communications system, the computer program product comprising a non-transitory computer-readable medium storing instructions executable by a processor to cause the UE to:

receive a request-to-send (RTS) signal in an unlicensed spectrum or a virtual RTS (V-RTS) in a licensed spectrum, the RTS signal or the V-RTS signal being addressed to a set of UEs.