Performance Optimization Of Inter-Satellite Laser Communication System With Pointing Error

The development of space remote sensing technologies puts forward higher requirements for data transmission rate in the inter-satellite communication links.Intersatellite laser communication has become the focus of current research because of its extremely high data transmission rate.In the inter-satellite laser communication system,the pointing error between the transmitter and the receiver will cause the random fluctuation of the received optical intensity signal,thus affecting the performance of inter-satellite laser communication.In order to further enhance the effectiveness and reliability of inter satellite laser communication systems,the influence of pointing error described by modified Raylaigh distribution on BER,outage probability and channel capacity of intersatellite laser communication system is analyzed,and the parameter selection methods are given to achieve the optimal system performance.(1)Considering the BEP performance,the model of inter-satellite laser communication system is established,and the closed expression of ABEP boundary is given by using the boundary of Gaussian Q function.Simulation results show that there is an optimal beam waist radius to optimize the BER performance,and the optimal beam waist radius decreases with the increase of pointing jitter and the transmitting power.(2)Considering the outage probability performance,the closed expression of the outage probability is given based on the transmission equation of inter-satellite laser communication link.The analytical expressions of the optimal root mean square width are given under certain outage probability and transmitting power respectively.Simulation results show that the outage probability can be optimized by selecting the optimal root mean square width of the transmitted beam.(3)Considering the channel capacity performance,the channel transfer probability matrix with pointing error is given,and the optimization model of mutual information is established.The Lagrange multiplier method is used to solve the model and the analytical expression of the optimal probability distribution of input signal is obtained.The simulation results show that the mutual information under the optimal probability distribution of input signal is significantly higher than that under the equal probability distribution of input signal.So,the system performance can be optimized by the optimal probability distribution design of input signal.(4)The traditional dynamic beam waist adjustment scheme is improved.Without any approximation,an instantaneous channel state model based on Marcum Q function is adopted,and the corresponding dynamic beam waist adjustment scheme is given.Simulation results show that the proposed dynamic beam adjustment scheme improves the system performance to a certain extent compared with the traditional dynamic beam adjustment scheme,and the performance gain increases with the decrease of transmiss-ion distance.