Effect of Macrodiversity and Microdiversity on Outages and Bit Error Rates in a Cellular System

Wireless service providers striving to improve the coverage of their systems or enlarge the cells' size can choose either one or a combination of two different diversity techniques, namely, microdiversity and macrodiversity. In this paper, we focus on Maximum Ratio Combining (MRC) in each base station and switching between base stations as a simple macrodiversity technique. The first technique requires adding antennas, radio resources and Digital Signaling Processing (DSP) power to each base station. The second is basically a fast response handoff mechanism that instantaneously, or with minimal delay, chooses the best base station to serve the mobile based on the signal power received. In many practical situations, "Switching Macrodiversity" (SM) is significantly cheaper to implement. It is therefore important to find and compare the improvement in coverage and "Bit Error Rate" (BER) that could be achieved by each scheme or by a particular combination of both techniques. However, while each technique has been thoroughly studied and implemented in different forms, the literature does not provide sufficient information for systems using both techniques. In this work, we obtain analytical results for outage (uncovered fraction of a cell) and BER for systems using a combination of both techniques to cover a desired area.