Optimization Algorithm Based On The Layer Interact Tcp Over, Gprs Performance Study

With the rapid development of network, mobile communication especially personal communication and Internet application have both experienced explosive growth rates since the 1990's. Nowadays, the demand of mobile devices to access the Internet has become more and more imminent. How to access the Internet any time and anywhere has become one of the hot research topics and the object of next generation personal communication.With its advantage of high usage of resource, fast data rate, always on line and low charges, GPRS(General Packet Radio Service), a step between GSM and 3G cellular networks, has been widespread all over the world.Unfortunately, the performance of Internet applications over wireless links is severely degraded by transmission errors. The Transmission Control Protocol (TCP) is the de facto standard for reliable data transmission in the Internet today. While TCP lias been tuned to work well over traditional wired networks, it does not adequately handle the vagaries of wireless media. The adverse effects arise primarily because TCP misinterprets wireless losses as being due to congestion. Especially, for TCP performance over GPRS, it has been greatly challenged by the characteristics of GPRS: high bit error rate, long delay and fast variation of RTT(Round Trip Time). In this thesis, we address these challenges in detail and design solutions to them and evaluate the perfonnance of them over GPRS by simulation. Our results show that these solutions improved their perfonnance greatly.Chapter 1 gives a brief introduction of the development of mobile data communication and the challenge brought by it. Then the contribution and structure of the thesis were described.Chapter 2 presents a detail survey on GPRS, its principle and development, its network architecture, its protocol stack, mobility management and data process.Chapter 3 is a systematic study on the TCP protocol and its performance over wirless network.. Based on that, several ways to enhance its performance are introduced and compared.Chapter 4 gives a brief introduction of the enviroment, methodology and topology of network simulation-ns2. Also the model of wireless link and the simulation topology of TCP over GPRS are presented.In Chaper 5, an implementation of a novel protocol, called Berkeley Snoop Protocol, over GPRS is presented. By analysing the degradation of Snoop performance over GPRS, we promote several methods to improve its performance by using the TCP options.In Chaper 6, the study of GPRS delay and the alogrithm to alleviate the spurious timeout, called Eifel, are presented. Finally the combination of Eifel alogrithm with Snoop is discussed.At last the conclusion and future work are proposed.