Selection Combining Upgrade Schemes for Mobile Units in Wireless Networks

Selection combining is considered for upgrading the performance of mobile units in wireless networks. Three upgrade schemes are considered: 2 antennas array, 3 antennas array in circular geometrical setting and 3 antennas in linear geometrical setting. The problem of diversity loss due to antennas proximity is addressed and an approach for decreasing the loss is proposed. The approach is based on the Karhunen-Loeve transform which is derived from the channel covariance matrix. As an example, the upgrade of mobile units in an IS-136 network is analyzed for Rayleigh fading channels. Performance is evaluated by computing the bit error rate, outage probability, average signal to noise ratio and mean switching rate of the considered schemes. Key-Words: Diversity methods, fading channels, wireless networks