A Simple Closed form Approximation of Average Channel Capacity for Weakly Turbulent Optical Wireless Links

Performance of optical wireless link is degraded by the presence of atmospheric turbulence induced fading. In this paper, a simple tight closed form expression for average channel capacity of optical wireless communication (OWC) system in weak atmospheric turbulence is given. The channel capacity of OWC systems employing spatial diversity reception with maximum ratio combining and equal gain combining over independent and identical turbulence induced fading channels is also computed using proposed expression. Results computed by employing our expressions are in excellent agreement with results based on numerical Monte Carlo simulations over permissible turbulence strength for a wide range of signal to noise ratio.