Multicast Sidelink Contention Window Adjustment Using Terminal Feedback
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Solution Overview
Problem
In wireless communication systems, there is a lack of adjustment solutions for setting the size of a contention window for data transmission in a multicast manner, particularly in scenarios without HARQ feedback, leading to potential conflicts and suboptimal data transmission performance.
Innovation Solution
A method for determining the size of a contention window based on feedback information from multiple terminal devices, adjusting the window size to account for multicast scenarios and potential conflicts, using conditions such as ACK/NACK ratios or blind retransmission counts to optimize channel access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed contention window size is used for multicast data transmission, then the channel access procedure is simple, but transmission conflicts increase and data transmission performance deteriorates
Solution Approach 1:
The patent applies dynamics by transitioning from a fixed contention window size to a variable contention window size that adapts based on transmission conditions. The terminal device adjusts the contention window size dynamically according to feedback information from multiple receiving terminal devices, enabling the system to respond to changing channel conditions and reduce transmission conflicts while maintaining manageable complexity through standardized adjustment rules.
2Reliability
If the contention window size is increased to reduce conflicts, then data transmission reliability improves, but channel access efficiency decreases
Solution Approach 1:
The patent applies parameter changes by adjusting the contention window size parameter based on feedback information from receiving terminal devices. When feedback indicates successful reception (ACK), the contention window size is reduced to improve channel access efficiency. When feedback indicates transmission failures (NACK), the contention window size is increased to reduce conflicts. This dynamic parameter adjustment optimizes both reliability and productivity by adapting to actual transmission conditions.
Solution Approach 2:
The patent implements feedback mechanisms where receiving terminal devices send acknowledgment information (ACK/NACK) back to the transmitting device. This feedback is used to adjust the contention window size for subsequent transmissions. The feedback loop enables the system to learn from past transmission outcomes and optimize future channel access decisions, balancing conflict reduction with access efficiency.
3Reliability
If random backoff is used for channel access, then collision probability is reduced, but channel access time increases
Solution Approach 1:
The patent applies dynamics by making the contention window size variable rather than fixed. The random backoff mechanism operates within this variable window, allowing the system to expand the window when conflicts are detected (increasing collision avoidance) and contract it when conditions are favorable (reducing access time). This dynamic adjustment optimizes the trade-off between collision avoidance and access time based on real-time feedback from the network.
Data Source
AI summary
Embodiments of this application provide a communication method, a communication apparatus, and a system. In the method, a terminal device obtains channel occupancy time COT, where the COT consists of N time units, and N is an integer greater than or equal to 1; sends first sidelink information to at least two terminal devices in a first time unit in the COT; determines a size of a contention window based on feedback information of the at least two terminal devices for the first sidelink information; and determines, based on the size of the contention window, a random backoff number for performing a channel access procedure, and sends second sidelink information based on a result of the channel access procedure.