Use of distributed antenna systems in maximizing data throughput in 3G microcellular systems-simulation study of the effect of correlated shadowing

The use of multiple geographically-distributed base station antennas to improve high speed multimedia service in a microcellular UMTS system is studied. Macro-diversity is used with widely separated antennas assuming micro-cells whose radii are in the range of hundreds of meters, and the effect of correlation between paths due to the smaller size of the cells is accounted for. Using a simulation of the downlink, assuming optimal power control and equal power allocation to all transmit-diversity branches, the geographical location of multiple base station antennas in hexagonal-shaped cells is varied to find the maximum bit rate for a varying number of active users randomly located in the cell. It is shown that the best location of the antennas need to be at a distance of 40-60% of the cell radius. Distributed antenna systems are found to be a good candidate for low processing gain, high-data rate transmissions.