Systems engineering of data services in UMTS W-CDMA systems

We address issues concerning technology selection for non-real time, near real time and interactive data services for 3G W-CDMA systems. Specifically, we compare the packet mode of operation with the circuit mode of operation in UMTS W-CDMA. We show that the use of packet channels such as the common packet channel (CPCH) and forward access channel (FACH) lead to an order of magnitude higher spectrum efficiency as compared to use of the dedicated channels. We also show in an example and under a set of service mixture assumptions that their use lead to a factor of 3.3 higher spectrum efficiency in the downlink and 21 in uplink, and to more than two order of magnitude resource utilization efficiency gain in the range of 2-134. Finally, CPCH offers eightfold increase in throughput and capacity efficiency as compared to the random access channel (RACH). We find that the level of resource utilization gain is sensitive to the level of burstiness of traffic as is the case with the spectrum efficiency gain