Removing the MAC Retransmission Times from the RTT in TCP

MAC retransmission of packets (for example in a video transfer) raises the RTT and leads to throughput decrease on TCP versions based on RTT for their sending rate. This is not the appropriate effect, because retransmissions are caused by temporary interferences, which often appear in wireless links. This paper deals with the effects of MAC retransmissions. A new TCP option is proposed, which fully takes into account the effect of MAC retransmissions. In this proposition wireless network cards have a timer which is initialised with the value of the option once the packet is sent the first time, and this value is stored in the option each time the packet is retransmitted. The exact time of retransmissions is then known by the source. Simulations show that the proposed mechanism increases throughput.

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