Investigation on the error performance of modulation formats in free-space optical communication links with turbulences

Free-space optical (FSO) communication system has become a popular option in the communication industry. This is due to the increasing demand of high-speed wireless optical links. The common wireless communication technology that is being deployed currently is the radio frequency (RF) technology. However, limited bandwidth and power efficiency are the vulnerabilities in this technology. FSO is then studied and developed to overcome some of the issues. FSO uses light to transmit information through air without any physical medium. It provides a flexible communication system as it is able to reduce power consumption to only half of power needed in radio frequency technology. It is a more preferred alternative compared to radio frequency technology, as it provides stable data transmission especially in the communications between terrestrial buildings. Our study shows that the bit-error-rate (BER) performance of the FSO communication system can be improved by implementation of modulation and signaling formats which is phase shift keying (PSK) in this paper. The lowest achievable BER can be obtained by applying quadrature phase shift keying (QPSK) under weak atmospheric turbulence.