A MIMO architecture for IEEE 802.16d (WiMAX) heterogeneous wireless access using optical wireless technology

Recently, there has been much interest in convergence in the communications industry: convergence of fixed and mobile terminals, convergence of optical and wireless networks, and convergence of wireless cellular and broadband platforms. At the core of the push for mobile broadband convergence is a user-centric model for next-generation networks that are envisioned to provide an array services "anytime, anywhere" reliably and cost-effectively. Solutions for this problem will undoubtedly require a cross-layer approach that considers everything from physical layer parameters, to scheduling and routing protocols. In this paper, we focus on heterogeneous fixed broadband topologies and study physical-layer convergence of optical and wireless networks. We adopt a point-to-point architecture and present a performance analysis of a multiple-input, multiple output (MIMO) hybrid RF/optical wireless system that implements the physical layer of the IEEE 802.16d WiMAX standard. The key technique of interest is multi-subcarrier modulation of OFDM signals on the optical carrier. Average power efficiency, atmospheric turbulence, adaptive modulation, receiver noise, as well as cross-layer protocol design are considered. Expressions for average symbol error rate are derived and evaluated to determine system performance. We thus assess optical wireless technology as a potential distributor of WiMAX traffic and highlight the MIMO advantage in such a hybrid system.