Hierarchical network structuring will be a central issue in future cellular networks. In the literature, many graph partitioning methods have been proposed to assign network elements to controllers to minimize network signaling. This paper presents two refinements to such methods, namely the connectedness and site constraints, to improve the spatial consistency of solutions, which is key for easy checking by the operator. Assessment is based on real problem instances of the assignment of base stations to packet control units in GSM-EDGE Radio Access Network (GERAN). Results show that fragmentation and overlapping in the final solution can be greatly reduced, while degrading the network performance only marginally.