Considerations for UMTS capacity and range estimation

In this paper, example uplink and downlink capacity and range estimation methods have been outlined. These have been limited to the single service case where the modem performance, multipath structure, environmental conditions and service rate are common to all users in the network. It has been found that uplink capacity estimation is primarily a function of modem performance and the F-factor. This is due to the dominance of other user noise over the thermal noise, even in lightly loaded cells, as well as the variability of the in-cell and out-of-cell noise (the F-factor). Simplifications to the downlink numerical modelling have been shown using fixed RAKE finger characteristics. These simplifications assume that the average channel conditions do not change with position, time or when the subscriber unit is in soft-handover. We have also considered the consequences of the simplified link-budget and user to interference margin mapping in the context of estimating capacity and range for a homogenous network. Homogeneity does not describe realistic network topologies; however, the generic case does give some indication of UMTS capabilities. Coupled with a numerical modelling technique, the methods outlined in this paper can help dimension the air-interface network for UMTS