The effect of reordering and dropping packets on TCP over a slow wireless link

Abstract

Transmission control protocol (TCP) is used by many standard data application in current wired networks. It has proven to work well in traditional networks where packets losses are mainly due to network congestion. On the other hand, a totally different scenario happens in the wireless link. Due to the high bit error rate (BER), TCP performance is affected. Many corrupted and delayed packets occur in the wireless link that result a poor performance of TCP. There have been a lot of schemes proposed to improve the performance of TCP over wireless networks. This paper discusses the behavior of TCP over a wireless slow link. The effects of dropping and reordering packets are studied. The network is simulated using the network simulator NS (Ref.13), a discrete event simulator targeted at networking research. The modeled link does not suffer from any congestion issues, and there are no intermediate routers where some packets could be dropped due to buffer exhaustion. The behavior and the performance of different TCP enhancement are compared to the new Reno. The TCP enhancements include limiting receiver's advertised window, selective acknowledgment (SACK) option, duplicate selective acknowledgment (D-SACK) option, limited transmit, and initial window of four segments.