EFR: a retransmit scheme for TCP in wireless LANs

Abstract

We propose a new, efficient fast retransmission (EFR) scheme for wireless LANs. Wireless LANs are becoming popular and providing an efficient protocol over a wireless link is important. In our experiments with the 2.4 GHz WaveLAN, the poor TCP performance observed was attributed to frequent expiration of the retransmission timer. To avoid unnecessary expiration of the retransmission timer, we propose a scheme in which fast retransmission is performed efficiently. The proposed modification only affects a TCP sender, and our version of TCP where the change is interoperable with existing TCP implementations. The change is especially effective in wireless LAN environments, where we have demonstrated significant improvements in throughput, 10-15%, via experiments.