Research on timer settings for the soft handover algorithm with different system loads in WCDMA

Abstract

The capacity of a CDMA system is mainly limited by mutual interference among mobile users, so system capacity and system performance depends highly on the system load, i.e., number of users per cell. On the other hand, one important measure for the signaling load in WCDMA is the number of handovers per time unit. In particular, the branch additions and releases for soft handover are crucial for the amount of signaling load in the network. The work to tradeoff between system capacity and signaling load in a cellular network needs to be considered. We investigate the soft handover algorithm known from the current 3rd Generation Partnership Project (3GPP) standardization with its timers to tradeoff the signaling rate against network performance which is defined by the satisfied user criteria as in ETSI SMG 2 UMTS 30.03. The effect of different loads given by the density of users is investigated and some instructive figures of timer settings according to the different load of the network are given in this paper. We have assumed speech service for our investigations.