Methods of Listen-Before-Talk Mechanism for Opportunistic Spectrum Access

Patent metadata

Field	Value
Publication number	US-2016309512-A1
Application number	US-201615098431-A
Country	US
Kind code	A1
Filing date	Apr 14, 2016
Priority date	Apr 15, 2015
Publication date	Oct 20, 2016
Grant date	—

Abstract

A method of determining and adapting a contention window size (CWS) based on channel loading for load-based equipment (LBE) listen before talk (LBT) channel access mechanism is proposed. The historic observations obtained from carrier sensing can reflect the state of channel loading, which is then used to adapt the maximal contention window size. A wireless device collects historical channel loading information including the number of idle slots and the number of busy slots. The wireless device uses the historical information to estimate the total number of active devices M in the wireless network and the channel-loading factor. The wireless device then computes the thresholds using the long-term value of M and then adapts the value of the CWS based on the channel-loading factor and the thresholds.

First claim

What is claimed is:

1 . A method, comprising:
determining a channel loading factor indicative of a channel loading by a wireless device adopting a load based equipment (LBE) listen-before-talk (LBT) mechanism in a wireless communication network, wherein the channel loading factor is based on a channel idle time sensed by the wireless device; determining a contention window size based on the channel loading factor; performing a backoff procedure to access the channel and generating a random backoff counter from the contention window size; and transmitting radio signals if the wireless device detects a channel idle condition for a period defined by the random backoff counter.

2 . The method of claim 1 , wherein the backoff procedure is an extended clear channel assessment (CCA) channel access procedure.

3 . The method of claim 1 , wherein the channel-loading factor is computed based on a relationship between the channel idle time and a total backoff time sensed by the wireless device.

4 . The method of claim 1 , wherein the channel-loading factor is computed based on a previous backoff procedure performed by the wireless device.

5 . The method of claim 1 , wherein the channel-loading factor is an average of channel loading factors computed based on a plurality of historical backoff procedures.

6 . The method of claim 1 , wherein the contention window size is determined based on a high channel-loading threshold and a low channel-loading threshold.

7 . The method of claim 6 , wherein the contention window size is increased if the channel loading is higher than the high channel-loading threshold.

8 . The method of claim 6 , wherein the contention window size is decreased if the channel loading is lower than the low channel-loading threshold.

9 . The method of claim 6 , wherein the thresholds are determined based on a total number of active devices in the wireless network.

10 . The method of claim 9 , wherein the wireless device further estimates the total number of active devices in the wireless communication network.

11 . A wireless device, comprising:
a channel loading calculator that computes a channel loading factor indicative of a channel loading in a wireless communication network, wherein the channel loading factor is based on a channel idle time sensed by the wireless device adopting a load based equipment (LBE) listen-before-talk (LBT) mechanism; a contention window size adaptor that adapts a contention window size based on the channel loading factor; an LBT channel access handler that performs a backoff procedure to access the channel and generates a random backoff counter from the contention window size; and a transmitter that transmits radio signals if the wireless device detects a channel idle condition for a period defined by the random backoff counter.

12 . The wireless device of claim 11 , wherein the backoff procedure is an extended clear channel assessment (CCA) channel access procedure.

13 . The wireless device of claim 11 , wherein the channel-loading factor is computed based on a relationship between the channel idle time and a total backoff time sensed by the wireless device.

14 . The wireless device of claim 11 , wherein the channel-loading factor is computed based on a previous backoff procedure performed by the wireless device.

15 . The wireless device of claim 11 , wherein the channel-loading factor is an average of channel loading factors computed based on a plurality of historical backoff procedures.

16 . The wireless device of claim 11 , wherein the contention window size is determined based on a high channel-loading threshold and a low channel-loading threshold.

17 . The wireless device of claim 16 , wherein the contention window size is increased if the channel loading is higher than the high channel-loading threshold.

18 . The wireless device of claim 16 , wherein the contention window size is decreased if the channel loading is lower than the low channel-loading threshold.

19 . The wireless device of claim 16 , wherein the thresholds are determined based on a total number of active devices in the wireless network.

20 . The wireless device of claim 19 , wherein the wireless device further estimates the total number of active devices in the wireless communication network.

Assignees

• Mediatek Inc

Inventors

• Li Chien-Chang
• Liao Pei-Kai
• Yang Weidong
• Chen Bo-Si

Classifications

• H04W74/085

  collision avoidance · CPC title

• H04W74/0816 Primary

  with collision avoidance · CPC title