Research On Access Algorithm Of Multibeam Satellite Supporting High Maneuvering Target

Under the trend of future integration of space,air and ground,more and more mobile terminals will be connected to satellite networks,and multibeam satellites will be the first choice for satellite networks because they support broadband communications.These mobile terminals include ultra-high-speed mobile devices such as low-orbit satellites and spacecraft,and will also include high-speed mobile devices such as aircraft and highspeed rail.When a high-speed mobile terminal is connected to a multibeam satellite,the carrier frequency offset and phase offset will change due to the Doppler effect,which is one of the main reasons for affecting the system performance.Therefore,this paper aims to correct the frequency offset and phase offset generated when the high maneuvering target communicates with the multibeam satellite and complete the access,and research the algorithm of high maneuvering target accessing multi-beam satellite.First,in view of the low spectral efficiency and low power utilization of the single-carrier modulation often used in the current multibeam satellite access link,this paper designs a multibeam satellite physical layer waveform based on continuous phase modulation(CPM),and designs a Multiuser access algorithm for the multibeam satellite return link.Finally,the designed access algorithm is simulated.Secondly,in order to solve the Doppler frequency offset problem when a high maneuvering target accesses a multibeam satellite in burst mode,a carrier synchronization algorithm for multibeam satellite burst communication is designed,which is based on the code-aid algorithm with Expectation Maximum as the coarse carrier synchronization algorithm.At the same time,an adaptive Gaussian process model-mean absolute soft output(GP-MASO)carrier fine synchronization algorithm is presented.This algorithm analyses the probability of MASO function getting the extreme value,and then obtains the extreme value of MASO function on line by using the parameters of Gumbel distribution obtained by weighted least squares estimation,so as to use the Gaussian estimation function to estimate the frequency offset of the system adaptively.The simulation results show that,combined with the coarse carrier synchronization algorithm,the proposed fine synchronization algorithm can estimate a wide range of Doppler frequency offsets with low parameter search complexity,the estimation results are close to the theoretical bound,and the system bit error rate(BER)loss is less than 0.1 dB.Thirdly,for the problem of phase tracking after frequency offset correction when high maneuvering targets are connected to multibeam satellites in a continuous mode,a carrier phase tracking algorithm for CPM multibeam satellite communication system is designed in this paper.The algorithm first compensates the modulation phase of the received CPM by using data-aid method,and then estimates the Doppler frequency offset and Doppler frequency offset rate of the high maneuvering target by using the structure of the second-order frequency locked loop aid third-order phase locked loop.On this basis,the phase correction of the high maneuvering target is completed by using the estimation result,and finally the high maneuvering target access in the continuous communication scenario is realized.The simulation results show that the frequency offset error is less than 0.5Hz when the algorithm is stable and the BER performance loss of the system is less than 0.1 dB.