CCA clearance in unlicensed spectrum

• US 10,159,049 B2
• Filed: 08/17/2017
• Issued: 12/18/2018
• Est. Priority Date: 06/24/2014
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Dabeer, Onkar, Damnjanovic, Aleksandar, Yerramalli, Srinivas, Chen, Wanshi, Somasundaram, Kiran Kumar, Bhushan, Naga
• Primary Examiner(s): Trinh, Tan H
• Application Number:
  US15/680,017
• Publication Number:
  US 20170374628A1
• Time in Patent Office: 488 Days
• Field of Search: 455 69, 455522, 455 631, 4551271, 455132, 455574, 455 6711, 455450, 455560, 370254, 370445, 370311, 370329, 370336, 370330, 370312, 370332, 370350, 370252, 370338, 370333, 709225
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04W 52/225 Calculation of statistics, e.g. average, variance
• CPC Class Codes: H04W 52/241 taking into account channel quality metrics, e.g. SIR, SNR, CIR, Eb/lo
• CPC Class Codes: H04W 52/243 taking into account interferences
• CPC Class Codes: H04W 52/246 where the output power of a terminal is based on a path parameter calculated in said terminal
• CPC Class Codes: H04W 52/262 taking into account adaptive modulation and coding [AMC] scheme AMC per se H04L1/0001
• CPC Class Codes: H04W 74/0808 using carrier sensing, e.g. carrier sense multiple access [CSMA]

Abstract

Techniques are described for contention-based wireless communications channel access that may improve the likelihood that a contention procedure will pass and allow a device to transmit an uplink or downlink transmission using the contention-based channel. Various disclosed techniques may determine a transmit power for a subsequent transmission based on channel characteristics during one or more clear channel assessment (CCA) time durations. The transmit power may be selected to provide a CCA threshold that may increase the likelihood that a device will win contention for the channel during the CCA procedure.

Claims

1. A method of wireless communication at a user equipment (UE), comprising:

measuring, by the UE, a shared channel during at least one time duration equivalent to a clear channel assessment (CCA) time duration prior to performing a CCA;

determining, by the UE, a channel condition of the shared channel during the at least one time duration based at least in part on the measuring;

adjusting, by the UE, prior to performing the CCA, at least one of a transmit power associated with a transmission from the UE following the CCA or a CCA threshold level of the CCA, wherein the adjusting is based at least in part on the determined channel condition; and

performing, by the UE, the CCA based at least in part on the adjusting, wherein the CCA is performed subsequent to the at least one time duration and during an uplink OFDM symbol period identified for use.

2. The method of claim 1, wherein the adjusting comprises:

adjusting the transmit power based on the channel condition, wherein the adjusted transmit power is a maximum transmit power; and

adjusting the CCA threshold level based on the adjusted transmit power.

3. The method of claim 2, further comprising:

transmitting one or more control signals using a higher transmit power than the adjusted transmit power; and

transmitting data signals at the adjusted transmit power.

4. The method of claim 1, wherein the adjusting comprises:

adjusting the CCA threshold level based on the channel condition; and

adjusting the transmit power based on the adjusted CCA threshold level.

5. The method of claim 1, further comprising:

adjusting a modulation and coding scheme (MCS) based on the determined channel condition.

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

monitoring the channel condition of the shared channel during a plurality of CCA time durations; and

determining an expected channel condition for a subsequent CCA time duration.

7. The method of claim 1, further comprising:

selecting at least one antenna of a plurality of antennas to be used for performing the CCA.

8. The method of claim 7, wherein performing the CCA comprises performing one or more CCAs using the selected antenna(s), the method further comprising:

determining that the shared channel is unavailable for transmission when an energy on the shared channel during the one or more CCAs exceeds the CCA threshold level; and

determining that the shared channel is available for transmission when the energy on the shared channel is less than the CCA threshold level.

9. The method of claim 7, wherein the determining comprises:

monitoring a plurality of channel conditions for each of the plurality of antennas during a plurality of CCA time durations; and

determining a plurality of expected channel conditions for each monitored antenna for a subsequent CCA time duration.

10. The method of claim 1, wherein the determining comprises:

determining at least one statistic for the channel condition based at least in part on the measuring.

11. The method of claim 10, further comprising:

transmitting the at least one statistic to a base station.

12. The method of claim 10, wherein the at least one statistic includes a cumulative distribution function (CDF).

13. The method of claim 1, further comprising:

receiving, from a base station, one or more of an adjusted transmit power, an adjusted CCA threshold, or a modulation and coding scheme (MCS) to be used for an uplink transmission, wherein the transmit power or the CCA threshold level is adjusted based at least in part on the receiving.

14. The method of claim 13, wherein the one or more adjusted transmit power, adjusted CCA threshold, or MCS are received semi-statically or dynamically.

15. An apparatus for wireless communication at a user equipment (UE), comprising:

a processor, and memory coupled to the processor, wherein the processor is configured to;

measure, by the UE, a shared channel during at least one time duration equivalent to a clear channel assessment (CCA) time duration prior to performing a CCA;

determine, by the UE, a channel condition of the shared channel during the at least one time duration based at least in part on the measuring;

adjust, by the UE, prior to performing the CCA, at least one of a transmit power associated with a transmission from the UE following the CCA or a CCA threshold level of the CCA, wherein the adjusting is based at least in part on the determined channel condition; and

perform, by the UE, the CCA based at least in part on the adjusting, wherein the CCA is performed subsequent to the at least one time duration and during an uplink OFDM symbol period identified for use.

16. The apparatus of claim 15, wherein the processor is further configured to:

transmit one or more control signals using a higher transmit power than the adjusted transmit power; and

transmit data signals at the adjusted transmit power.

17. The apparatus of claim 15, wherein the processor is further configured to:

adjust a modulation and coding scheme (MCS) based on the determined channel condition.

18. The apparatus of claim 15, wherein the processor is further configured to:

monitor the channel condition of the shared channel during a plurality of CCA time durations, and wherein determining the channel condition of the shared channel comprises determining an expected channel condition for a subsequent CCA time duration based at least in part on the monitoring.

19. The apparatus of claim 15, wherein the processor is further configured to:

select at least one antenna of a plurality of antennas to be used for performing the CCA.

20. The apparatus of claim 15, wherein the processor is further configured to:

determine at least one statistic for the channel condition based at least in part on the measuring; and

transmit the at least one statistic to a base station.

21. The apparatus of claim 15, wherein the processor is further configured to:

receive, from a base station, one or more of an adjusted transmit power, an adjusted CCA threshold, or a modulation and coding scheme (MCS) to be used for an uplink transmission, wherein the transmit power or the CCA threshold level is adjusted based at least in part on the receiving.

22. An apparatus for wireless communication at a user equipment (UE), comprising:

means for measuring, by the UE, a shared channel during at least one time duration equivalent to a clear channel assessment (CCA) time duration prior to performing a CCA;

means for determining, by the UE, a channel condition of the shared channel during the at least one time duration based at least in part on the measuring;

means for adjusting, by the UE, prior to performing the CCA, at least one of a transmit power associated with a transmission from the UE following the CCA or a CCA threshold level of the CCA, wherein the adjusting is based at least in part on the determined channel condition; and

means for performing, by the UE, the CCA based at least in part on the adjusting, wherein the CCA is performed subsequent to the at least one time duration and during an uplink OFDM symbol period identified for use.

23. The apparatus of claim 22, further comprising:

means for transmitting one or more control signals using a higher transmit power than the adjusted transmit power; and

means for transmitting data signals at the adjusted transmit power.

24. The apparatus of claim 22, further comprising:

means for adjusting a modulation and coding scheme (MCS) based on the determined channel condition.

25. The apparatus of claim 22, further comprising:

means for determining at least one statistic for the channel condition based at least in part on the measuring; and

means for transmitting the at least one statistic to a base station.

26. The apparatus of claim 22, further comprising:

means for receiving, from a base station, one or more of an adjusted transmit power, an adjusted CCA threshold, or a modulation and coding scheme (MCS) to be used for an uplink transmission, wherein the transmit power or the CCA threshold level is adjusted based at least in part on the receiving.

27. A non-transitory computer-readable medium storing computer-executable code for wireless communication at a user equipment (UE), the code executable by a processor to:

measure, by the UE, a shared channel during at least one time duration equivalent to a clear channel assessment (CCA) time duration prior to performing a CCA;

determine, by the UE, a channel condition of the shared channel during the at least one time duration based at least in part on the measuring;

adjust, by the UE, prior to performing the CCA, at least one of a transmit power associated with a transmission from the UE following the CCA or a CCA threshold level of the CCA, wherein the adjusting is based at least in part on the determined channel condition; and

perform, by the UE, the CCA based at least in part on the adjusting, wherein the CCA is performed subsequent to the at least one time duration and during an uplink OFDM symbol period identified for use.

28. The non-transitory computer-readable medium of claim 27, wherein the code is further executable by the processor to:

transmit one or more control signals using a higher transmit power than the adjusted transmit power; and

transmit data signals at the adjusted transmit power.

29. The non-transitory computer-readable medium of claim 27, wherein the code is further executable by the processor to:

determine at least one statistic for the channel condition based at least in part on the measuring; and

transmit the at least one statistic to a base station.

30. The non-transitory computer-readable medium of claim 27, wherein the code is further executable by the processor to:

receive, from a base station, one or more of an adjusted transmit power, an adjusted CCA threshold, or a modulation and coding scheme (MCS) to be used for an uplink transmission, wherein the transmit power or the CCA threshold level is adjusted based at least in part on the receiving.