Improved TCP Hybla: A TCP enhancement for link with high RTT and error rate

Different networks has different transport layer issues, because of that issues, traditional TCP protocols cannot give optimized performance. Transport layer issues for satellite network are high RTT and high link error rate of satellite link. Due to high RTT and high link error rate, congestion window of traditional TCP protocol does not increase up to the level to utilize available bandwidth. TCP Hybla was proposed to solve problem of high RTT in satellite link, it tries to obtain same data transmission rate as of reference wired connection. TCP Westwood is proposed for wireless link where packet loss can be due to link error because of high link error rate. TCP Westwood adjusts its congestion window after packet loss according to bandwidth used by the connection. This paper proposes Improved TCP Hybla, Hybla-i protocol that addresses both the issues of satellite link. Hybla-i combines approach of TCP Hybla to solve the problem of high RTT and approach of TCP Westwood to solve the high link error rate problem. It continuously calculates bandwidth used by the connection; this bandwidth is used to set the congestion window when packet loss occurs. TCP Hybla-i is implemented in NS2 for NS2-TCP-Linux patch.