Improving the performance of switched diversity with post-examining selection

Switched diversity offers one of the lowest complexity solutions for fading mitigation. The receiver employing switched combining schemes seeks and uses an acceptable diversity path for data reception. When no acceptable path is found after all paths have been examined, however, the receiver randomly chooses an unacceptable path. In this paper, we consider the performance improvement of switched combining schemes. In particular, we modify the conventional switch and examine combining (SEC) scheme in a way such that the best path is selected when there is no acceptable path. For the resulting SEC with post-examining selection (SECps) scheme, we carry out a thorough performance analysis over fading channels. Noting that SECps can be viewed as selection combining (SC) with an output threshold scheme, we perform a tradeoff study of performance versus complexity between SECps and SC. The analytical results are illustrated with some selected numerical examples.