Unlicensed Band Channel Access via Random Backoff and Defer Duration
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Solution Overview
Problem
The increasing demand for cellular communication due to smart devices has led to spectrum shortages, making it challenging to maintain communication quality in licensed frequency bands, and using unlicensed frequency bands introduces interference issues with conventional wireless devices.
Innovation Solution
A method and apparatus for efficiently accessing and sharing channels in unlicensed frequency bands by determining if a channel is idle during a defer duration and performing random backoff based on a counter value, allowing for uniform probability within a contention window, and adjusting the counter decrementing operation to ensure fair channel access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If unlicensed frequency band is used to provide cellular communication service, then spectrum availability is improved, but interference with conventional wireless devices and communication quality guarantee become problematic
Solution Approach 1:
The base station performs channel sensing during a defer duration before actual transmission to detect whether the channel is idle. This preliminary action allows the system to check for existing transmissions from conventional wireless devices and avoid interfering with them, thus resolving the contradiction between utilizing unlicensed spectrum and preventing interference
Solution Approach 2:
The system implements a feedback mechanism where the base station continuously monitors the channel status during the random backoff time interval. Based on the detected channel state (idle or busy), the base station adjusts its transmission timing and counter decrementing operation, enabling adaptive coexistence with conventional wireless devices while maintaining spectrum utilization
2Quantity of substance
If multiple communication facilities use unlicensed band simultaneously without limit, then spectrum utilization is improved, but communication quality guarantee becomes difficult
Solution Approach 1:
The base station dynamically adjusts its channel access behavior by performing random backoff with counter decrementing operations. The counter value is decremented based on channel conditions and a predetermined probability, allowing the system to adaptively control transmission timing and maintain reliable communication quality while utilizing unlicensed spectrum efficiently
Solution Approach 2:
The system changes the parameter of transmission timing by introducing random backoff intervals and conditional counter decrementing. This parameter modification allows multiple communication facilities to share the unlicensed band dynamically, ensuring that transmissions occur only when channel conditions are favorable, thus maintaining communication quality while maximizing spectrum utilization
3Ease of operation
If random backoff with uniform probability is implemented, then fair channel access is improved, but access delay increases
Solution Approach 1:
The base station performs counter decrementing operations partially - only when the channel is detected as idle during the random backoff time interval. This partial action approach maintains fairness through uniform probability selection while reducing unnecessary waiting time, as the counter is decremented only under favorable channel conditions rather than continuously
Solution Approach 2:
The system uses self-service mechanisms where the base station autonomously monitors channel conditions and adjusts its own transmission timing based on detected idle periods. This self-service approach enables fair channel access through randomized backoff while minimizing access delay by immediately utilizing available idle channel opportunities without requiring external coordination
Data Source
AI summary
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.