Spatial Reuse Prioritized Channel Access in Dense WLANs
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Solution Overview
Problem
In dense wireless local area networks (WLANs), existing Clear Channel Assessment (CCA) schemes fail to optimize network throughput as they do not differentiate between stations with varying spatial reuse capabilities, leading to inefficient channel access and reduced overall throughput due to equal contention probabilities for all stations below a fixed CCA level, regardless of their interference levels.
Innovation Solution
A spatial reuse prioritized channel access scheme is introduced, where stations with higher spatial reuse capability, determined by co-channel interference signal strength from overlapping basic service sets (OBSSs), are given a higher probability to win channel access contention by adjusting EDCA parameters such as contention permit probability, initial counting down value, and counting down speed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed CCA level is used for all stations, then channel access contention is simple to implement, but network throughput is reduced due to equal contention probabilities for all stations regardless of their spatial reuse capabilities
Solution Approach 1:
The patent applies local quality by differentiating channel access parameters based on each station's spatial reuse capability. Stations are classified into different groups (first group with higher spatial reuse capability, second group with lower capability) and assigned different EDCA parameters. This allows the system to optimize throughput for stations that can tolerate higher interference while maintaining fairness for stations that are more interference-sensitive, thereby resolving the contradiction between implementation simplicity and network throughput optimization.
2Productivity
If CCA level is increased to enhance spatial reuse, then simultaneous transmissions in multiple OBSSs increase, but stations with lower spatial reuse capability lose channel access opportunities
Solution Approach 1:
The patent changes the CCA threshold parameter dynamically based on spatial reuse capability. The first CCA threshold level is set higher than the second CCA threshold level. Stations in the first group (with higher spatial reuse capability) use the higher threshold, allowing them to transmit simultaneously in overlapping BSSs. Stations in the second group (with lower spatial reuse capability) use the lower threshold, ensuring they retain channel access opportunities. This parameter differentiation resolves the contradiction by allowing spatial reuse optimization without completely excluding low-capability stations.
3Ease of operation
If all stations below CCA level have equal contention probability, then channel access is fair and simple, but overall network throughput is suboptimal due to inability to prioritize high spatial reuse capability stations
Solution Approach 1:
The patent segments the station population into distinct groups based on spatial reuse capability measurements. Stations are divided into a first group (higher capability) and a second group (lower capability). Each group is assigned different contention parameters including different CCA threshold levels and different EDCA parameters. This segmentation allows the system to prioritize channel access for high-capability stations that can contribute more to spatial reuse, while still providing controlled access to low-capability stations, thereby optimizing overall network throughput while maintaining a manageable level of fairness.
Data Source
AI summary
A spatial reuse prioritized channel access scheme is proposed to enhance the average throughput per station in a wireless network by optimizing spatial reuse. Spatial reuse capability (SRC) is defined as a monotonically decreasing function of co-channel interference signal strength from OBSSs. Higher spatial reuse capability can be transformed into higher data rate or less usage of airtime by using higher MCS or less interferences to OBSSs by reducing TX power. By allowing the stations that have larger spatial reuse capability to have higher probability to win channel access contention, the overall network throughput is enhanced.