Performance analysis of multibranch switched diversity systems

We investigate the performance of multibranch switched diversity systems. Specifically, we first derive generic formulas for the cumulative distribution function, probability density function, and moment-generating function of the combined signal power for both switch-and-stay combining (SSC) and switch-and-examine combining (SEC) schemes. We then capitalize on these expressions to obtain closed-form expressions for the outage probability and average error rate for various practical communication scenarios of interest. As a byproduct of our analysis we prove that for SSC with identically distributed and uniformly correlated branches, increasing the number of branches to more than two does not improve the performance, but the performance can be different in the case the branches are not identically distributed and/or not uniformly correlated. We also show that, in general, the SEC performance improves with additional branches. The mathematical formalism is illustrated with a number of selected numerical examples.