Optimal combiners in optical wireless systems with spatial diversity and pre-amplification

Abstract

We present analytical results on the operation of a pre-amplified optical wireless communication (OWC) system that also takes advantage of spatial diversity to improve its outage probability and average bit-error-rate (BER) performance against turbulence induced fading. The paper focuses on the design of an optimal electronic combiner that minimizes the instantaneous BER for any given channel state by properly adjusting the gains that are provided to each receiver output after detection. We demonstrate that the optimal combiner performs in a similar manner to an equal gain combiner for a limited number of receiving elements in moderate turbulence, while its potential can be harvested in systems with high diversity factors or under the strong-to-saturated turbulence regime.