Adaptive access control of CSMA/CA in wireless LANs for throughput improvement

This paper presents an adaptive access scheme for Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) aiming to take advantage of multi-user diversity and improve throughput, while supporting distributed and asynchronous operation. By assigning channel-adaptive access probabilities to different users, this method prioritizes users who gain most from using a channel, and hence, improves channel utilization in comparison with a simple random access scheme. Furthermore, in this method, access probabilities are designed to achieve long-term fairness by keeping a same average access probability for all users. Performance of the proposed adaptive CSMA/CA is evaluated in terms of collision probability and saturation throughput by analysis and simulation. Illustrative and analytical results show that A-CSMA/CA significantly improves the throughput by controlling contention among users and decreasing the collision probability, specifically in a large network.