Performance Analysis of Collision Avoidance MAC Protocol in Multi-hop Wireless Ad-hoc Network

Performance analysis of 802.11Medium Access Control (MAC) protocol has been carried out either by means of simulation or by means of analytical models with simplified back-off rule assumptions. BinaryExponential Back-off (BEB) is the widely used back-off mechanism in many contention-based IEEE 802.11 MAC protocols for its simplicity and good performance, but it has drawbacks especially in multi-hop ad hocnetwork and some new back-off schemes such as Multiplicative Increase and Linear Decrease (MILD) and Double Increment Double Decrement (DIDD) were proposed. This paper, investigate the performance ofcollision avoidance MAC protocol in multi-hop wireless ad-hoc network by adopting MILD back-off mechanism. A three state Markov chain is used to model the channel states and node states. These models were used to derive the duration time, steady-state probabilities of the states of node and throughput of Mobile Ad-hoc NETwork (MANET). Simulation results show no matter the value of average number of neighbors,transmission range , and length of DATA frames , the throughput of MANET always achieves the maximum value at some point of persistent probability and also the throughput of a MANETs increases with increase in persistent probability which is influenced by the number of neighbors, transmission range and length of DATA frame. On the other hand the throughput decreases with increase in sensing range which is also influenced by the number of neighbors, transmission range and length of DATA frame.