A Monte Carlo simulation approach to finding optimal parameter settings for soft handovers in WCDMA

The aim of this paper is to find the optimal parameter settings for the WCDMA soft handover algorithm as described by the 3GPP standards and the impact on the system performance. The various layers involved during a soft handover are modelled inclusive of the physical layer, layer 2 and layer 3. Event based handover is considered in terms of a handover being triggered by the reporting of certain events. Utilising Monte Carlo simulations, the effect of soft handover parameters are investigated to determine the effect on soft handover boundaries in a suburban morphology. The optimal set of parameter values can now be determined and provide insight on what can be expected prior to implementation in a live network. The proposed parameter settings were trialled and validated in a live WCDMA network. Experimental results showed that the optimal settings implemented in the network did significantly improve soft handover performance and drop call rate, thereby improving the subscriber experience.