Performance Evaluation of Multi-Radio Transmission Diversity for TCP Flows

The effect of the TCP congestion control mechanism over rapidly fluctuating wireless links is a deterioration of the TCP performance. The utilization of multi-radio accesses in future networks by means of packet scheduling and dynamic access selection enriches the arsenal of solutions that mitigate radio channel variations. Packet scheduling over multiple radio accesses at link level provides a novel diversity scheme referred to as Multi-Radio Transmission Diversity (MRTD). This work evaluates, through simulations, the effects of different MRTD schemes for TCP flows over heterogeneous radio links. Results indicate that MRTD schemes provide substantial gains in terms of goodput and show a significant reduction in file download times. These gains are due to the diversity obtained and the suppression of the unwanted duplicate acknowledgements that frequently cause degradation in TCP performance over a radio channel.