UMTS coverage and capacity enhancement using repeaters and remote RF heads

For the evolving 3rd generation UMTS networks, there is a need for coverage and capacity enhancement with the flexibility of solutions. The target of this paper is to evaluate and propose a scheme for UMTS network upgrade, with the coexistence of repeaters and remote RF heads as solution to improve the network coverage and capacity. A step-by-step study of the UMTS network with repeaters and remote RF heads in a downlink limited system is presented. Results from dynamic system level simulations for circuit switched services under varying traffic distributions are evaluated. The simulation results indicate that, repeaters, in principle, are useful to enhance the network coverage. Proper tuning of repeater gain is essential. Nevertheless, additional gain on using repeaters in an already optimized pure macro network is limited. The results show that, at system level, networks enhanced with a mixture of repeaters and remote RF heads can carry significantly more traffic than the pure macro network. The antennas mounted below rooftops in such a network, yields considerable improvement in the signal-to-noise-plus-interference ratio (SNIR) of the common pilot channel (CPICH). Roughly 50% reduction in downlink power consumption was observed. Thus, during the initial UMTS network upgrade, repeaters could be added to the macro cells to enhance coverage. Further, some or all of the repeater locations can be reused and converted to remote RF heads when additional capacity requirement arises.