Packet service in UMTS: delay-throughput performance of the downlink shared channel (DSCH)

The Universal Mobile Telecommunications System, wide band code-division multiple access (W-CDMA) radio interface is characterized by great flexibility and a variety of different physical and logical channel types: for example, on the downlink the dedicated channels (DCH) offers circuit switching, the downlink shared channel (DSCH) and forward access channel use packet switching, the former with closed loop power control. Furthermore, several user rates and protections are possible, by choosing suitable parameters, such as spreading factors (SFs), code rates and automatic repeat request (ARQ) schemes. In this paper we present the results, obtained by a detailed simulation, about the effect of several parameters and system alternatives on the capacity of the downlink segment of the W-CDMA interface with packet service. In particular, we investigate the effect of the SF, the code rate, the ARQ and the power control on the DSCH capacity and delay-throughput performance.