OFDM Wireless Optical Communication Systems with Serial Relays Over Exponentially Modeled Turbulence Channels

The optical wireless communication systems attract very significant research and commercial interest, the last years, due to their high availability, and performance characteristics with relatively low installation and operational cost. On the other hand, due to the fact that the optical channel which is used in this technology is the atmosphere, their performance depends strongly on the atmospheric conditions and the link’s characteristics. Thus, the effective distance that these systems can cover is relatively short. Thus, in many cases where the long distance signal propagation using wireless optical systems, is necessary, relay nodes are used. In this work, we study the performance of a wireless optical system, which is using the orthogonal frequency division multiplexing (OFDM) technique and relay nodes which decode and retransmit the received signal, over atmospheric turbulence channels modeled with the negative exponential distribution. For this system, we derive closed form mathematical expressions for its outage probability and average bit error rate (BER). Finally, we present the corresponding numerical results for realistic cases with common parameter values