UMTS border planning issues

Border planning issues for UMTS due to the limited number of frequency carriers per UMTS operator are investigated. Performance degradation due to the coexistence of two cellular networks using the same frequency carrier is evaluated through system level simulations. The effect of different system parameters on performance degradation is also studied. The critical factor is the "degree of overlapping" between the two networks. It is defined as the percentage of users within the networks that are closer, in terms of radio conditions, to the base stations of the other network. It is concluded that uncoordinated border situations can result in important co-channel interference, creating significant capacity loss to both home and foreign UMTS networks. Solutions to this problem have to be investigated in order to optimise the coverage of border areas.