Cell density requirements for UMTS network planning

Cell planning for the Universal Mobile Telecommunications System (UMTS) is challenging due to the interrelationships between coverage, capacity, service requirements and the power control mechanism inherent to the system. This means that classical coverage models, adopted from second generation systems are insufficiently detailed for UMTS cell planning purposes. An important stage in the cell planning process is network dimensioning to determine the required cell density. This can be used to guide the deployment of infrastructure and assess the optimality of operational networks. Highly efficient cell placement is important for UMTS since transmission infrastructure and site costs will account for a substantial proportion of total network costs. In this paper, we show how link budget and capacity analysis can be used to derive estimates on the minimum number of cells required to support a particular mix of UMTS services. For typical service requirements, we show how key factors in the model, such as service type, load, propagation environment and system parameters affect the minimum required cell density. We also demonstrate points at which cell density requirements change dependency on coverage and capacity based requirements.