PERFORMANCE STUDY OF AN . IMPROVED SELECTIVE REPEAT PROTOCOL WITH ADAPTIVE RATE - BASED FLOW CONTROL SCHEME

Abstract

Progress in the field of high-speed networking and distributed applications has lead to a debate in the research community on the stability of existing protocols such as TCP/IP for emerging applications over high-speed networks. Protocols have to operate in a complex environment comprised of various performance characteristics like delay, throughput and queuelength. Maximizing bandwidth utilization and providing performance guarantees, in the context of high-speed networking are two incompatible goals. Various protocols which have been proposed use, as a part or a whole, the basic Selective-Repeat ARQ protocol. Recovery of every packet in error through retransmission is very expensive measured in terms of badwidth and delay. It is thus desirable to avoid the unnecessary retransmissions. In this dissertation, a new Selectiver-Repeat ARQ strategy named High-Speed Selective Repeat (HSR) protocol has been simulated which provides a very fast error recovery mechanism. Unlike other ARQ strategies this strategy -ensures- .that---a-=-co-r-recd-y---rece-i-ved --packet --will- -not----be retransmitted. In addition a Rate-based flow control mechanism is implemented to keep the excess load out of the network. Through simulation this new scheme is found to outperform the existing TCP-Slow Start scheme in two important areas: Average Delay and Throughput Efficiency.