Analysis of beam divergence and input bit rate for free space optical communication link

Free Space Optical (FSO) communication has emerged as a highly relevant technology to meet the growing demand for high bandwidth, low latency and cost effective installations applications for its advantages over RF communication. In this paper, we investigate the impact of beam divergence over input data rate using BPSK (Binary Phase Shift Keying) and OOK (On Off Keying) modulation schemes. This study is motivated by the need to enhance the performance of adaptive data rate methods. The adaptive data rate method can further reduce the bit error rate (BER) and outage probability of FSO link. The impact of laser beam divergence and link distance is also investigated for BPSK and OOK modulation techniques to evaluate the FSO link performance in terms of BER. This study shows that the performance of free-space optical channel can be improved by controlling the internal parameters of FSO communication system, which are laser beam divergence, optical transmission power and receiver aperture area. Also, in case of non-stationary free-space optical network, if a flight control mechanism is available, the FSO link can be adjusted to achieve increased performance.