Wide-Band Satellite Characteristic Channel Simulation Technology And FPGA Implementation

Satellite communication is an important part of the sixth-generation mobile communication system,because it has advantages of large coverage and doesn’t affected by land disasters.Satellite communication can make up for the defect of insufficient coverage of terrestrial cellular systems.Compared with terrestrial wireless communication networks,satellite communication has obvious advantages,but because of its greater broadcast and complexity,it is easily affected by complex spatial fading,Doppler frequency shift,bad weather and other factors.Moreover,in order to ensure that the system can still work normally under the actual satellite link,it is now necessary to carry out repeated tests during the system development process,resulting in high cost.Therefore,designing a suitable set of channel simulators is of great significance for the development and testing of the system.This paper conducts in-depth research from the following aspects:This paper firstly introduces the related concepts of wireless channels,expounds the characteristics of various fading channels,and further discusses the problems existing in the existing satellite channel models.At the same time,the helicopter rotor occlusion and the nonlinear distortion phenomenon in the satellite forwarding process are introduced,and the influence of the unique application scenarios in the satellite communication system on the signal is improved.Aiming at the poor generality of various channel models in satellite communication systems and the many but imperfect channel models corresponding to some functions,this paper proposes a universal broadband satellite channel model.The model fully considers the existing satellite channel models,including free space path loss,shadow effect,rain attenuation effect,multipath effect,Doppler frequency shift and other models.At the same time,the rotor occlusion phenomenon in the helicopter communication scene and the nonlinear distortion phenomenon in the satellite transponder are also considered.In addition,the model is also adaptable to high-throughput satellite signals operating in the Ka-band,so the application scenarios supported by the model are more comprehensive.Aiming at the realization of the Field Programmable Gate Array(FPGA)of the satellite channel simulator,according to the proposed channel model,this paper designs a channel simulator hardware architecture that supports high bandwidth and has low complexity.The architecture can support Gaussian noise module with configurable bandwidth,rainfall attenuation module,dynamic Doppler frequency offset module,flat fading module,helicopter rotor shielding module,nonlinear distortion module and digital frequency conversion module.of each function.At the same time,the host computer software supporting the channel simulator is designed,which can realize flexible selection of channel functions,real-time configuration of parameters and visualization of results.Finally,a high-throughput satellite system hardware test platform is built,and the functions of each module of the satellite channel simulator are tested,which proves the correctness of the system.