A modified back-off algorithm for the IEEE 802.11 DCF

The primary medium access control (MAC) technique of IEEE 802.11 is called distributed coordination function (DCF). This protocol adopts a carrier sense multiple access with collision avoidance (CSMA/CA) with truncated exponential backoff to access the channel. The protocol performance mainly depends on backoff procedure which reduces the probability of collision. In this paper, we deal with the distributed inter-frame space (DIFS) overhead due to DIFS periods resulting in the backoff procedure. A modified backoff procedure is proposed that minimizes the DIFS overhead. This overhead is more significant at higher data rates and degrades the protocol performance. We present the effect of DIFS overhead on the throughput and delay performance of the basic access mechanism for the finite number of stations under ideal channel conditions. Simulation results of modified backoff procedure are compared with the original DCF performance.