Performance research of multiple access of satellite formation flying laser communication in atmospheric turbulence

A novel multiple access model of satellite formation flying is brought forward, which has the advantages of shared signal bandwidth, asynchronous access etc, at the same time it overcomes the problems of difficulty of constructing the addressing codes in the optical code division multiple access and that of hardware implementing in wavelength division multiple access. The model makes use of delay difference between two arms of Mach-Zender interferometer (MZI) to encode and decode at the end of transmitter and receiver respectively, that's to say when the delay difference of receiving end is close to that of transmitting end, the received optical power would be maximum. Frequency shift keying modulation is adopted to achieve the coherent multiplexing multiple access. Then when the micro-satellite beam is transmitted in atmosphere condition of weak turbulence, the receiving optical field is described by the Rytov model based on the premise of independent optical field interference, the formula of SNR and BER is deduced. The simulation results show that given the turbulence amplitude, 1/SNR ascends along with increasing of satellite number, furthermore the larger turbulence amplitude, the more quickly 1/SNR rises, this proves number of satellites and turbulence amplitude are the dominating parameters which affect the system performance.