Method, apparatus, and system for channel access in unlicensed band

• US 10,624,130 B2
• Filed: 06/20/2018
• Issued: 04/14/2020
• Est. Priority Date: 12/24/2015
• Status: Active Grant

• Current Assignee: Beijing Xiaomi Mobile Software Co., Ltd. (Xiaomi Corp.)
• Original Assignee: WILUS Inc.
• Inventors: Noh, Minseok, Kwak, Jinsam, Son, Juhyung
• Primary Examiner(s): Jagannathan, Melanie
• Application Number:
  US16/013,918
• Publication Number:
  US 20180302927A1
• Time in Patent Office: 664 Days
• 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 27/26 Systems using multi-frequency codes H04L27/32 takes precedence
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04W 72/0446 Resources in time domain, e.g. slots or frames
• CPC Class Codes: H04W 72/1221 based on age of data to be sent
• CPC Class Codes: H04W 72/21 in the uplink direction of a wireless link, i.e. towards the network
• CPC Class Codes: H04W 72/569 of the traffic information
• 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

Abstract

A base station and terminal in a wireless communication system is disclosed. Each of the base station and the terminal of the wireless communication system includes a communication module and a processor. The processor is configured to determine whether a channel is idle during a defer duration, determine whether the channel is idle during a random backoff time interval determined based on an initial value of a counter and a slot duration that is a constant time unit when the channel is idle during the defer duration, wherein the initial value of the counter is determined based on a random value, and perform a transmission when the channel is idle during the random backoff time interval. The random number is obtained with a uniform probability within a contention window that is an integer set by the base station.

Claims

1. A base station of a wireless communication system, the base station comprising:

a communication module; and

a processor,

wherein the processor is configured to;

determine whether a channel is idle during a defer duration,

when the channel is idle during the defer duration, perform a counter decrementing operation including decrementing a value of a counter by 1 in a random backoff time interval and determining whether the channel is idle during one slot duration, wherein the random backoff time interval is determined based on an initial value of the counter and a slot duration that is a constant time unit, wherein the initial value of the counter is determined based on a random number,

determine whether the channel is idle during an additional defer duration having the same duration as the defer duration when the channel is not idle during the one slot duration,

when the channel is busy during any one of a plurality of slot durations included in the additional defer duration, determine whether the channel is idle during the additional defer duration from an end of the slot duration determined to be busy,

repeat the counter decrementing operation until the value of the counter reaches 0 when the value of the counter is not 0, and

perform a transmission when the value of the counter is 0,

wherein the random number is obtained with a uniform probability within a contention window that is an integer set by the base station.

2. The base station of claim 1, wherein when the initial value of the counter is 0, the processor is configured to access the channel without sensing whether the channel is idle during the one slot duration after the defer duration.

3. The base station of claim 2, wherein the processor is configured to determine whether the initial value of the counter is 0 at an end of the defer duration, and access the channel when the initial value of the counter is 0.

4. The base station of claim 1, wherein the processor is configured to perform the transmission without sensing whether the channel is idle during the one slot duration when the value of the counter is 0 at an end of the additional defer duration.

5. The base station of claim 1, wherein the processor is configured to selectively decrement the value of the counter by 1 during the counter decrementing operation.

6. The base station of claim 1, wherein the processor is configured to determine the initial value of the counter to be a value larger than the random number.

7. The base station of claim 6, wherein the processor is configured to determine the initial value of the counter to be a value larger by 1 than the random number.

8. The base station of claim 1, wherein the defer duration is determined based on a channel access priority class of traffic included in a data channel to be transmitted through the transmission.

9. An operating method of a wireless communication system, the method comprising:

determining whether a channel is idle during a defer duration,

when the channel is idle during the defer duration, performing a counter decrementing operation including decrementing a value of a counter by 1 in a random backoff time interval and determining whether the channel is idle during one slot duration, wherein the random backoff time interval is determined based on an initial value of the counter and a slot duration that is a constant time unit, wherein the initial value of the counter is determined based on a random number,

determining whether the channel is idle during an additional defer duration having the same duration as the defer duration when the channel is not idle during the one slot duration,

when the channel is busy during any one of a plurality of slot durations included in the additional defer duration, determining whether the channel is idle during the additional defer duration from an end of the slot duration determined to be busy,

repeating the counter decrementing operation until the value of the counter reaches 0 when the value of the counter is not 0, and

performing a transmission when the value of the counter is 0,

wherein the random number is obtained with a uniform probability within a contention window that is an integer set by the base station.

10. A user equipment of a wireless communication system, the user equipment comprising:

a communication module; and

a processor,

wherein the processor is configured to;

determine whether a channel is idle during a defer duration,

when the channel is idle during the defer duration, perform a counter decrementing operation including decrementing a value of a counter by 1 in a random backoff time interval and determining whether the channel is idle during one slot duration, wherein the random backoff time interval is determined based on an initial value of the counter and a slot duration that is a constant time unit, wherein the initial value of the counter is determined based on a random number,

determine whether the channel is idle during an additional defer duration having the same duration as the defer duration when the channel is not idle during the one slot duration,

when the channel is busy during any one of a plurality of slot durations included in the additional defer duration, determine whether the channel is idle during the additional defer duration from an end of the slot duration determined to be busy,

repeat the counter decrementing operation until the value of the counter reaches 0 when the value of the counter is not 0, and

perform a transmission when the value of the counter is 0,

wherein the random number is obtained with a uniform probability within a contention window that is an integer set by the user equipment.

11. The user equipment of claim 10, wherein when the initial value of the counter is 0, the processor is configured to perform the transmission without sensing whether the channel is idle during the one slot duration after the defer duration.

12. The user equipment of claim 10, wherein the processor is configured to perform the transmission without sensing whether the channel is idle during the one slot duration when the value of the counter is 0 at an end of the additional defer duration.