WiMAX over Free-Space Optics - Evaluating OFDM Multi-Subcarrier Modulation in Optical Wireless Channels

This paper analyzes performance of optical wireless communication systems with multi-subcarrier OFDM as set out in the IEEE 802.16-2004 WiMAX standard. Average power efficiency, atmospheric turbulence, adaptive modulation as well as various noise models are considered. Performance is evaluated in a simulation environment with symbol error probability as the metric of interest. Results indicate that smaller constellation sizes are better suited for the optical wireless channel, as they provide larger Ps gains for relatively small increases in average received optical power and are more resilient to atmospheric turbulence. Furthermore, although increasing the number of subcarriers N degrades performance since total optical power is fixed by laser linearity constraints, with proper design, optical wireless technology is capable of distributing WiMAX.