Effect of aperture averaging and spatial diversity on capacity of optical wireless communication systems over lognormal channels

Abstract

In this paper it is evaluated average channel capacity of an optical wireless communication system with aperture averaging and diversity reception over lognormal channels using a simple approximate closed form expression. The qualitative improvement in channel capacity is compared and investigated for various turbulence mitigation techniques: namely aperture averaging, diversity techniques such as maximal ratio combining and equal gain combining. Based on our study it is found that aperture averaging gives reasonably improved performance as compared to both types of diversity reception beyond certain turbulence strength. However, irrespective of turbulence strength, substantial improvement in capacity may be achieved with an array of direct detection receivers. Results obtained using the proposed expressions are in excellent agreement with those based on Monte Carlo simulations.