In the design of radio networks, the problem of cellular planning is of critical importance. The present paper addresses the problem of determining the minimum number of Base Stations required to cover a design area, the associated optimal cell sizes and the best topographical configurations for the cells, while meeting system performance requirements. The problem is formulated as a Set Partitioning Problem, where the requirements of radio coverage, non-uniform traffic distribution, and the topographical constraints are taken into account. A highly efficient Branch and Bound algorithm is then used for obtaining guaranteed optimal solution. By considering a range of benchmark network problems that have appeared in the literature, it is shown that the proposed technique has a significantly superior performance to other known techniques.