Multiuser Diversity Over Parallel and Hybrid FSO/RF Links and Its Performance Analysis

Hybrid free-space optical (FSO)/radio-frequency (RF) communication has emerged as an effective solution for high-data-rate wireless transmission. In this paper, multiuser diversity over parallel and hybrid FSO/RF links is discussed. We present and analyze a hybrid FSO/RF point-to-multipoint system that consists of a hybrid access point (HAP), multiple FSO users, and multiple RF users. Either an FSO user or an RF user is scheduled to communicate with HAP at each transmission block. We propose a link quality scheduling strategy. The statistical characterizations of the proposed strategy are derived. Based on these characterizations, the outage probability and the average bit error rate are also analyzed. Novel asymptotic closed-form expressions at high signal to noise are derived. The multiuser diversity gain and diversity order for this scheduling strategy are further discussed. Numerical results are given to validate all the analytical results.