Performance enhancement technique for TCP over mobile ad hoc networks

Ad hoc networks are wireless networks of mobile nodes, self-organizing systems formed by co-operating nodes within communication range of each other that form temporary networks in which the topology rapidly changes result from the movement of mobile nodes. This frequent topology may lead to sudden packet losses and delays. So, the current implementation of TCP for the Internet is not efficient when used for mobile ad hoc networks. This is because TCP dose not show a satisfactory performance in mobile ad hoc networks due to a high BER (Bit Error Rate) and node mobility. Base TCP-Vegas does not recognize the distinction between congestion and packet losses because of transmission errors, which are current in mobile ad hoc networks. In particular, when a route is re-established it requires to be set CWND in accordance with the new route characteristic. In this paper, we propose a method to improve the TCP performance over mobile ad hoc network using new additional new module to TCP-Vegas. With this module sender node distinguishes between congestion and transmission errors it effectively adjusts the TCP's CWND and transmission rate. Simulation results using OPNET show that the proposed scheme increase TCP throughput compared with those of general TCPI.