Signal detection algorithm in free-space optical communication systems with distributed transmit antennas

The distributed multiple-input multiple-output(MIMO) technique is one of the effective ways to mitigate the effect of atmospheric turbulence and reduce the packet error rate in free-space optical communications.Because the time of laser propagation is different and random among atmospheric turbulence links,signals arrive at the receiving antennas randomly and asynchronously,which causes the problem of inter-symbol interference.But linear detection algorithms are more complicated to solve it for the free-space optical(FSO) system with distributed transmit antennas.The valuable information obtained from signs of distributed receiving antennas depends on combining mode,and the performance of anti-interference is determined by the detection algorithm.Focusing on the problem above,this paper proposes the algorithm based on maximum likelihood detection and Neyman-Pearson(NP) fusion criterion for distributed receiving antennas system.Simulation results show that when receiving signal is synchronous,NP algorithm has better robustness,it is comparable to optimal combining(OC) algorithm,and it is better than the equal gain combining(EGC) algorithm.When receiving signal is asynchronous,NP algorithm is better than EGC and OC algorithms,which improves spatial diversity performance in the distributed antennas system,suppressing inter-symbol interference.