Abstract:
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) has been used for so many years in 802.11 WLANs for its simplistic nature. A Binary Exponential Backoff (BEB) is used here so that each contending station in a network is chosen randomly. However the overall throughput of the network degrades drastically due to random nature of backoff mechanism. Therefore an alternate contention mechanism is required to overcome this problem. To overcome this problem of MAC inefficiency, we propose a modified backoff mechanism for MAC which can order the contending station by predictive backoff values of others stations. We use a hash based backoff mechanism to resolve the initial contention of the contending stations and after each successful transmission a fixed slot is assigned to each individual station. Therefore, our proposed approach contain the combination of backoff mechanism which is predictive hash based backoff for initial contention and modified deterministic backoff after successful trans- mission. In this way, a collision free schedule can be created and can support a large number of contenders. The simulation study show that the proposed scheme reduces the contention overhead and can gain high efficiency compared to standard channel access
