An improved IEEE 802.11 CSMA/CA medium access mechanism through the introduction of random short delays

Abstract

The work in this paper studies the performance of Carrier Sense Multiple Access/Collision Avoidance (CSMA/CA) medium access control (MAC) mechanism in IEEE 802.11 DCF. From studying the propagation delay and clock synchronization differences between terminals, it is concluded that the slight timing differences, effectively a relative jitter, contributes to reducing the probability of collisions after a MAC backoff. This lesson is leveraged in a presented new CSMA/CA MAC technique that deliberately introduces a random short delay, akin to jitter, in the backoff slots time structure. The new medium access technique is evaluated through both an analytical model and simulations that consider the realistic timing constraints set in the IEEE 802.11 standard. Simulation results show improvements in normalized saturated throughput with the new technique from at least 14% for 10 nodes up to 26% for 50 nodes.