Dimensioning Telstra's WCDMA (3G) network

Abstract

Loss models can be used to determine engineered capacity of circuit-switched telecommunications systems. They readily model the multi-service, multi-resource nature of call admission control (CAC) schemes for such systems, including service prioritization via the use of resource reservation. Third generation wireless networks (3G) are incredibly complex with regard to system resources and supported services. In particular, the 3G radio environment is subject to interference and fading. Recognizing that communications systems are engineered to a nominal “time consistent busy hour”, we seek a method for capturing the behavior of the 3G radio environment over such a time period, and incorporating it into a modified loss model for determining capacity. We present a novel methodology to derive environmental parameters that can be used to characterize the radio environment as it affects individual cells in the network. Consequently we have developed a 3G radio access network (RAN) and transport network (TN) dimensioning tool for Telstra that, on a per cell and hourly basis, estimates spare capacity based on target grades of service (GoS). These incorporate loss probabilities for all services, and throughput requirements for high speed downlink packet access (HSDPA) services. This integrated network management tool calculates each resource's utilization at various envelope boundary points to determine the active resource constraints, thereby allowing Telstra engineers to most effectively apply capacity expansions to the RAN & TN.