Soft handover gain in WCDMA

This paper deals with the WCDMA intra frequency soft handover, where the mobile station is connected simultaneously to several base stations on the same frequency. The first part of this paper estimates the advantage of using soft instead of hard handover in order to extend coverage (soft handover gain). The results show that the soft handover gain increases, when the soft handover enter threshold increases. The second part evaluates to which extent additional interference, due to soft handover in downlink, influences the system quality of service (only speech users are considered). It has been found that, when the traffic load increases over a certain value, the interference in downlink can nullify the advantage brought about by maximal ratio combining. Finally, on the basis of the second analysis, this study outlines how the system can dynamically adapt the soft handover enter threshold in order to improve the capacity of the system, while maintaining the same quality.