Comparative Performance Evaluation for DCF and CONTI MAC Schemes

Abstract

This paper compares the performance analysis of a Medium Access Control (MAC) scheme named Distributed Coordination Function (DCF) with a much efficient scheme called Constant Time Contention (CONTI)by varying number of contending nodes, thus suggesting the better scheme with regard to parameters such as delay, throughput, collision rate and jitter. DCF[4], which is used as the MAC scheme for IEEE 802.11 standard, uses Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol with carrier sense and collision avoidance mechanisms through random back-offs[12]. Its major limitation is its collision rate increases with increase in number of nodes, and thereby in an increase in delay parameter. Other MAC schemes, which are proposed after DCF, resulted decrease in the collision rate but, they utilize variable number of time slots to resolve the contention problem. Unlike these schemes, CONTI considered both the issues by resolving the contention problem with less number of collisions in constant time with a decrease in delay.