Throughput comparison between RACH and CPCH in 3GPP

Two uplink common channels using random access techniques are defined in the Universal Mobile Telecommunications System (UMTS): random access channel (RACH) and common packet channel (CPCH). For a better utilization of UMTS resources, it is very important to predict the performance of these channels. We present new expressions to compute the success probability in both channels and, based on these results, we compare the throughput of the channels. Also, we show some conditions to maximize the performance of RACH and CPCH.