Performance Evaluation of QoS by Combining Medium Access Control and Slow Start in MANETS

This paper evaluates the performance evaluation of interaction between Transport and the MAC layer protocols operating in a mobile adhoc network. In Adhoc networks, certain QoS parameters like error rate, delay and packet loss are increased and certain parameters like throughput and delivery ratio are decreased in Transport layer is due to MAC problems and disconnection is also possible due to mobility or power failure. So, combine the mechanisms of these two layers improve the QoS drastically. We examine the effects of two different MAC protocols— IEEE 802.11and IEEE802.11e with Slow start mechanism of TCP. Specifically, we access the impact of multiple wireless hops and node mobility on the throughput performance of TCP on each MAC protocol. Additionally the other Qos parameters of throughput, delay, Bandwidth delay product, delivery ratio and packet loss using slow start of TCP mechanism with two different MAC protocols is also investigated. Results show that in all instances, the QoS parameters 15-20% improvement in throughput, 40-45% improvement in bandwidth-delay product, 10-15% improvement in delivery ratio in IEEE 802.11e than IEEE802.11 and packet loss is reduced drastically to 40-50% in IEEE802.11e where only 3-5%delay is higher in IEEE802.11e than IEEE802.11.