Research And Implementation Of Spectrum Division And Recombination Technology In Satellite Communication

As the demand for high-speed and security of satellite communication services continues to increase,satellite communication systems should continue to evolve in terms of related technologies and overall architecture to meet the growing needs of users.However,the development of satellite communication systems is subject to two obvious shortcomings: First,the spectrum resources of satellite communication systems are limited,but the fixed spectrum allocation methods in traditional satellites and the idle discrete frequency bands that cannot be fully utilized have aggravated the problem of infrequent spectrum resources.Secondly,the satellite signal covers a large area,the signal is more easily intercepted,and the communication security is reduced.The traditional spread spectrum security technology will lead to the reduction of system communication efficiency.Under such circumstances,the filter bank multi-carrier technology combining Cognitive Radio(CR)with spectrum division,scrambling and recombination is applied to the satellite communication system,which is undoubtedly the solution to the two satellite communications shortcoming.First,cognitive radio can efficiently use dynamic channel spectrum resources to improve communication efficiency.Second,the system can solve the problem that the large bandwidth signal can't access the spectrum scattered channel by using this highly dynamic spectrum division and recombination technique to achieve arbitrary bandwidth segmentation of signals,and the system anti-interception performance is also significantly improved.Third,the split and division filter bank technology does not need to change the modulation mode of the original satellite communication.Therefore,this paper studies and analyzes the related technologies and existing problems of spectrum division and recombination.The main contents of the paper are as follows:(1)This paper explains the limitations of the existing multi-carrier communication technology of terrestrial communication in satellite communication,and discusses the basic principles and technical advantages of the division and recombination filter bank technology,deduct the key technologies of spectrum division and recombination technology.In addition,this paper builds a spectrum division and recombination communication system through simulation software,verify and analyze the spectrum division and recombination communication system and performance under QPSK signal.(2)This paper analyzes the phase distortion problem caused by the large delay of the transmission link of the satellite communication system,the pilot phase compensation method and the blind phase compensation method in the division and recombination filter bank technology.And according to the simulation software,the paper verifies the feasibility of pilot-based phase compensation method and blind phase compensation method.(3)The FPGA baseband implementation scheme and synchronization scheme of spectrum division and recombination communication system are designed in this paper.The spectrum division and recombination communication system of QPSK signal and the digital logic circuit of synchronization algorithm are designed by Verilog language,and the sequential logic verification is performed inside the FPGA.At the same time,this paper analyzes the occupation of FPGA resources and other issues.(4)Aiming at the problem of high complexity of spectrum in traditional signal segmentation and aggregation technology,this paper combines chirp spread spectrum signal with spectrum division and recombination,and uses the time-frequency uniformity of Chirp signal to design a time domain shaping window algorithm,and proves the equivalent effect with frequency domain filtering through theoretical analysis,which greatly reduces the computational complexity and improves the aggregation robustness.