Dynamic Contention Window Update via HARQ Feedback
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Solution Overview
Problem
In 5G NR systems, accurately determining the contention window (CW) for channel access on unlicensed bands is challenging due to the finer resource division, which affects channel access efficiency and user experience.
Innovation Solution
A method for dynamically updating the contention window based on HARQ feedback, where the CW size is adjusted according to the proportion of ACKs and NACKs received, allowing for more flexible resource transmission units and improved channel sensing mechanisms.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the contention window is dynamically updated based on HARQ feedback in 5G NR systems with finer resource division, then the channel access efficiency and measurement precision are improved, but the device complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where the sending device updates the contention window size based on HARQ-ACK feedback received from receiving devices. The processor determines whether to increase or reset the CW by evaluating HARQ-ACK states (ACK, NACK, DTX) and their proportions, creating a closed-loop control system that continuously adapts the contention window based on actual channel conditions and transmission outcomes
Solution Approach 2:
The patent makes the contention window dynamic by allowing it to be adjusted in real-time based on HARQ feedback proportions. The CW transitions between different states (increase or reset to minimum) depending on channel conditions, transforming a static parameter into a dynamically adaptive one that responds to changing environmental conditions
2Productivity
If the contention window is updated more frequently based on HARQ feedback, then the channel access efficiency is improved, but the loss of time for processing feedback increases
Solution Approach 1:
The patent applies partial action by updating the contention window based on the proportion of HARQ-ACK feedback rather than processing every single feedback individually. By evaluating the aggregate proportion of ACKs, NACKs, and DTX states, the system achieves effective channel adaptation without the overhead of processing each feedback message separately, thus balancing efficiency with time consumption
Data Source
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AI summary
Embodiments of this application provide a contention window management method applied to an unlicensed band, including: sending, by a sending device, one or more data packets to one or more receiving devices in one reference time unit or a plurality of reference time units, where the one or more data packets occupy a first bandwidth; receiving, by the sending device from the one or more receiving devices, a hybrid automatic repeat request HARQ or HARQs for the one or more data packets; and determining, by the sending device, a contention window CW size of a second bandwidth with reference to the HARQ or HARQs for the one or more data packets. According to the method provided in this application, contention window CW update can be determined based on a HARQ feedback for a data packet, to improve communication efficiency.