|M.Sc Student||Skarbovsky Alina|
|Subject||Performance Evaluation and Modeling of TCP over Cellular|
|Department||Department of Computer Science||Supervisor||Professor Dan Raz|
With wireless communication becoming widespread in the world, the number of mobile devices connected to the Internet via wireless links increases rapidly, making wireless networks an integral part of the Internet. Nowadays, the GSM wireless cellular networks are widespread all around the world, most of them providing GPRS (General Packet Network) services to their clients, which enables “always-on" data connections at theoretical rates of wired telephone modems. The performance of TCP protocol over these networks is extremely important, since it has a profound effect on the overall performance as experienced by the end user. Moreover, many of the technologies used in today's GPRS are adopted in the upcoming EDGE protocol, and thus our findings are likely to apply to future networks as well. We have performed a study of the characteristics of real GPRS networks and their effect on the performance of TCP, based on extensive tests performed over several operational GPRS networks. We present measurements of the actual characterization of such networks, concentrating on parameters that affect the end-to-end TCP behavior, such as excessive queuing, and packet reordering (in addition to the traditional loss, bandwidth and RTT parameters). Our results indicate that the internal GPRS network characteristics, not specified by the standard, play a major role in the end-to-end performance of the transport layer protocols and applications using them.