Performance analysis of the TCP behavior in a geo satellite environment

The paper shows the main problems that the Transmission Control Protocol (T CP) meets in a Geo Stationary Orbit (GEO) satellite environment characteriz ed by high 'delay per bandwidth product'. In a GEO environment, the delay i n the delivery of a message is very high, the Round Trip Time (RTT) is abov e 500 ms. These characteristics heavily affect the acknowledgement mechanis m on which the TCP is based and the performance of the protocol is much low er than in cable networks. The paper proposes and analyses possible solutions aimed at mitigating the negative effect and at improving the performance. A real test-bed is used t o carry out the study: two remote hosts are connected together through a sa tellite link in the Ka-band (20-30 GHz) by using IP routers. The system has been tested by using a ftp-like application, that allows transferring data of variable size between the two hosts. This is due to the observation tha t most of the Internet multimedia applications, as browsing and distance le arning, use massive file transfer. The protocol behavior is investigated both by tuning the parameters buffer size and initial congestion window and by modifying the dynamic characteris tics of the slow start algorithm. The analysis itself allows suggesting sol utions and taking decisions. (C) 2001 Elsevier Science B.V. All rights rese rved.