Downlink transmit power issues in a WCDMA cellular system

After many years of standardisation third generation cellular systems have now reached the deployment phase. Prior to this deployment, a dimensioning and planning stage is necessary to assess the radio access network coverage and capacity. A critical downlink issue of radio capacity and coverage planning is the power allocation required per user to fulfil network GoS requirements. Indeed, each Node B within a WCDMA system has a finite power resource that has to be shared amongst a number of users, or more accurately links elements (including users in soft handover). The consequent capacity of a 3G cellular system is dependant on the adequate resource sharing of the Node B transmit power. Three fundamental parameters describe this power: 1. The total transmit power 2. The pilot power 3. The allocated transmit power per dedicated traffic channel (DCH). This paper discusses the impact of these tuneable parameters on capacity, coverage, QoS and consequently GoS in a WCDMA network.