Influence of adaptive RTS/CTS retransmissions on TCP in wireless and ad-hoc networks

The trend of wireless networking is growing. This is due to the success of IEEE 802.11 WLAN technology, which allows the extension of local area networks by mobile stations and establishing of ad-hoc networks. The latter does not need any pre-installed infrastructure. Nodes communicate directly or the traffic is relayed over intermediate wireless nodes. While there are only few nodes the performance of the network is acceptable, but with increasing number of nodes their performance of the network decreases. If TCP is used additional performance degradation is expected. However, TCP is necessary since most applications and application level protocols are based on it. The poor performance of TCP in wireless networks has several reasons, especially the communication medium with high bit error rates (BER) and TCP´s optimization on fixed networks. In this paper, we present an analysis of TCP´s performance in wireless and ad-hoc networks. We emphasize the role of MAC layer retransmissions without breaking the end-to-end semantic of TCP. For this, we introduce the dynamic short retry limit, which allows the adaptation of RT-S/CTS retransmission.