Wireless TCP in Unfair Situation: Performance Degradation and Improvement
Waselul Haque Sadid, Mohammod Abul Kashem, M. A Rahman · 2009
Abstract — Traditional TCP implementations are tuned to work well over wired networks. A packet loss is occurred in a wired network mainly due to network congestion. On the other hand in a wireless link packet losses are caused mainly due to bit errors resulted from noise, interference, and various kinds of fadings. TCP performance in these environments is impacted by three path characteristics, not normally present in wired environments: high bandwidth delay product, packet losses due to corruption and bandwidth asymmetry. Wireless TCP has no idea whether a packet loss is caused by congestion or bit error. TCP assumes loss is caused by congestion and turns on its congestion control algorithms to slow down the amount of data it transmits as well as adopts retransmission policy. Invoking congestion control for bit errors in wireless channel reduces TCP throughput drastically. We propose an empirical architecture to recover these bit errors at Data Link Layer dynamically before entering the frame into buffer which reduces the number of retransmission at TCP level and thus preserves time to send more data, as our simulation results show. Consequently overall throughput can be increased where retransmission technique is almost 100 % ineffective for unfair noisy channel.