Effect of pointing error on cooperative free space optical communication systems under different channel conditions

We have investigated the performance improvement of cooperative free space optical (FSO) communication over single input single output (SISO) system in this paper. Bit error rate (BER) analysis for gamma-gamma channel model, pointing error and additive white Gaussian noise (AWGN) has been demonstrated for SISO and cooperative system, as well as, where the performance improvement with different combining techniques in cooperative system has been discussed in this paper. Significant performance improvement is achieved in case of cooperative communication with the use of Maximal Ratio combining as compared to Equal Gain combining and Selection combining diversity combining techniques as reported in literature where pointing error deteriorates the system performance. Different channel environments, where direct and indirect links are facing different turbulence, are also analyzed in this paper.