Performance Analysis of TCP and its Enhancement for Quality of Service in Mobile Wireless Networks in Single Traffic Using Prioritised Hard Handoff (PH2)

The research activities in mobile computing and wireless networks strongly indicates that mobile computers and their wireless communication links will be an integral part of the current internet works. Communication over wireless links is characterised by limited bandwidth, high latency, high bit-error rates and temporary disconnections. Most often, networks with wireless links and mobile hosts incur significant losses due to handoff. It is also most important that in wireless environment TCP (transmission control protocol) causes degraded end-to-end performance. In this paper, we tried to give solutions to these problems. We adopt a new method to improve the end-to-end reliable transport performance in mobile wireless environment by incorporating changes to network-layer at the base station and mobile host and preserve end-to-end semantics of TCP. The methodology employs NDG (normalised delay gradient) loss-predictor function to determine congestion losses from that of transmission loss. The sender window can adjust its size depending on the loss information. If the loss is due to congestion, congestion control algorithm is invoked to decrease the flow rate. If the loss is due to handoff (transmission loss), immediate-recovery algorithm is invoked to recover the losses caused by the sender TCP. Stochastic equations are used to analyse, i) arrival rate handoff calls, ii) blocking probability of handoff request, iii) distinguish packet loss due to congestion or handoff, iv) dynamics of sender window, v) queue length at the ingress point of the BS router , vi) throughput, and vii) the losses due to congestion and handoff blocking. Our results provide better way understanding the problem of calls drop due to handoff, and providing most accurate solutions for mobile wireless system.