UMTS radio planning: optimizing base station configuration

The planning of UMTS radio networks must take into account not only signal levels in the service area but also signal quality requirements since in the W-CDMA air interface the radio resources are shared by all base stations. In previous work we have proposed discrete optimization models and algorithms for the UMTS base station location problem. However, optimizing BS configuration is often more critical than BS location since service providers may have a very limited set of candidate sites due to authority constraints. We address the general problem of optimizing base station locations as well as their configurations, such as antenna height, tilt, and sector orientation. We describe a mathematical programming model which considers the power control mechanism typical of W-CDMA and the signal-to-interference ratio (SIR) as quality measure. The two contrasting objectives of the optimization process are traffic coverage maximization and installation costs minimization. A tabu search algorithm is proposed to find good approximate solutions of this NP-hard problem. Numerical results obtained for synthetic but realistic instances are also presented.