Congestion Control and Performance Improvement of Ad-hoc Networks by Increasing Throughput and Reducing Delay

A medium access control (MAC) protocol decides when competing nodes may access the radio channel, and tries to ensure that no two nodes are interfering with each other’s transmissions. In this paper we propose a QoS model for wireless ad hoc networks. Unlike other models it provides stochastic end to end delay guarantees using a routing protocol called GPSR (Greedy Perimeter Stateless Routing) protocol. After the routing is over the packets transmission is done through CTMAC (Concurrent Transmission MAC) protocol with fragmentation. The packets are transmitted concurrently where concurrent transmission is possible. CTMAC inserts additional control gap between the transmission of control packets (RTS/CTS) and data packets (DATA/ACK), which allows a series of RTS/CTS exchanges to take place between the nodes in the vicinity of the transmitting, or receiving node to schedule possible multiple, concurrent data transmissions. It completely utilizes the channel bandwidth and increase the fairness of each flow without causing congestion. This increases the throughput. The results shows us that the throughput of QoS model, where network flow is identified using GPSR protocol and packets are transmitted through CTMAC protocol with fragmentation, is increased when compared with the throughput of CTMAC protocol alone.