Buffer management for TCP over HS-DSCH

Abstract In this paper we investigate the influence of buer,management for TCP on performance of the High Speed Downlink Channel (HS-DSCH) introduced in WCDMA release 5. HS-DSCH is a shared channel, but user data is buered,individually prior to the wireless link. Three queue man- agement principles, e.g., passive queuing, the Packet Discard Prevention Counter (PDPC) method,and the Random Early Detection (RED) algo- rithm were evaluated for a number of buer,sizes and scenarios. Also, a buer,large enough to prevent packets from being lost was included for reference. For round robin (RR) scheduling of radio-blocks, PDPC and the pas- sive approach, that both manage to keep the buer short, gave the best system goodput,as well as the shortest average transfer times together with the excessively large buer.,With signal-to-interference ratio (SIR) scheduling, the strategy to avoid all packet losses, resulted in a lower system goodput than for the short buers. As illustrated in this article, peak transfer rates may not be achieved with very small buers, but buers of 10-15 IP packets seem to represent a good trade-o between transfer rates, delay and system goodput. We would like to investigate how,to make,use of system parameters such as the current amount of data oered,for HS-DSCH in total to regulate