TCP Performance Enhancement for UMTS Access Network

We aim at optimize the TCP performance over UMTS access network challenged by the large delay bandwidth product that is mainly caused by the latency from the link layer ARQ retransmissions and diversity technique at physical layer. We propose to place a split TCP proxy at GGSN nodes which is between UMTS access network and Internet. The split proxy divides the bandwidth delay product into two parts, resulting in two TCP connections with smaller bandwidth delay products. Simulation results show, the split TCP proxy can significantly improve the TCP performance under high bit rate DCH channel scenario (e.g.256 kbps). Besides, the split TCP proxy brings more performance gain for downloading large files than downloading small ones. Finally, an aggressive initial TCP congestion window size at proxy can brings even more performance gain for radio links with high data rates DCH channels with large delay bandwidth product.