Joint uplink and downlink capacity considerations in admission control in multiservice CDMA/HSDPA systems

Abstract

TCP-based data flows generate packets and ACKs in two directions, be it in the wireline or wireless networks. In the latter case, packets are typically found in the downlink whereas ACKs are in the uplink. Those two links are asymmetric in the case of CDMA-based High Data Rate (HDR)/High-Speed Downlink Packet Access (HSDPA) systems, the uplink being much slower than the downlink and thus, in some cases, restrictive in terms of the achievable throughput of the TCP flow. The aim of this work is to evaluate the performance of such a setting, in the presence of both streaming and elastic traffic, under a dynamic scenario where users arrive to the system and leave it after completion of their service. We specifically quantify the impact of the uplink on the overall performance of TCP and study the model variations according to several parameters such as load, file size and radio conditions 1 .