Design Of Transmission Method For Broadband Sky-wave Massive MIMO Communication

Skywave communication has the characteristics of ultra-long communication distance and communication coverage of thousands of kilometers,as well as the advantages of short construction period,strong mobility and low maintenance cost,which are suitable for special situations such as ocean going,disaster relief,and combat readiness,which can make up for the shortcomings of terrestrial cellular networks.Defects in communication range and emergency capability.On the one hand,the existing sky wave communication is mainly narrow-band communication,and its communication bandwidth is small,and the communication capability cannot meet the needs of wide-area coverage communication.On the other hand,the single-antenna configuration is mainly used,and it is difficult to effectively improve the spectrum utilization rate and coverage capability.Based on the analysis of sky wave channel characteristics and link budget,this paper studies the multi-carrier technology for broadband sky wave communication,and then introduces the massive MIMO technology and efficient coding and decoding technology in 5G into the sky wave communication system to form broadband massive MIMO sky wave communication Waveform technology,greatly improve the system capabilities,and build a broadband sky wave communication prototype verification system to complete the experimental verification of the external environment.Firstly,this paper analyzes the properties of sky-wave channel,expounds the characteristics of ionosphere,sky-wave fading,multipath transmission,Doppler effect,available frequency window and optimal operating frequency for communication.According to the nature of sky wave,the transmission model of sky wave is systematically analyzed,and different ionospheric reflection models are listed.On this basis,the gain of massive MIMO array to sky wave communication system is analyzed.For the research,the mature ionospheric prediction software Proplab is used to supplement the model,the link capacity is analyzed according to the results,and the sky wave channel measurement experiment is carried out through the experimental platform to further verify the sky wave channel characteristics and massive MIMO spatial resolution characteristics.Secondly,on the basis of reviewing the existing sky-wave multi-carrier technology,a broadband skywave communication technology based on fast convolution multi-carrier technology is proposed to meet the needs of broadband communication and flexible bandwidth allocation.Starting from the asynchronous frequency division multiple access signal model,the fast convolution method is used to realize the synthesis and analysis of multi-carrier filter banks.The proposed FCMC-based multi-carrier sky-wave communication technology not only maintains the advantages of flexible sub-band allocation,but also solves the shortcomings of OFDM multi-carrier technology in sky-wave communication,such as difficulty in supporting asynchronous communication and large out-of-band leakage.Thirdly,in order to improve the communication rate and link stability of sky wave communication,a5G-integrated broadband massive MIMO sky wave communication system is proposed.Combined with 5G high-efficiency encoding and decoding technology and massive MIMO technology,based on the multi-carrier technology mentioned above,the reception equalization algorithm and beamforming technology of sky wave communication are designed.On this basis,an automatic link establishment mechanism is designed to maintain the stable operation of the link.Using MATLAB to simulate the performance of the sky-wave communication link designed by this system,the proposed sky-wave communication system has good performance in the simulation environment.Finally,based on the research on the key algorithms of broadband large-scale sky-wave communication,combined with the characteristics of the antenna array and radio frequency transceiver unit of the actual skywave communication system,a baseband processing implementation architecture based on optical switching and soft baseband processing is proposed.The baseband signal processing subsystem and prototype terminal of the prototype system on the base station side are used to complete transmit signal processing algorithms such as LDPC coding,waveform modulation,and FCMC multi-carrier synthesis,and receive signal processing algorithms such as multi-carrier decomposition,waveform demodulation,and LDPC decoding.The implementation and deployment in the base station architecture enables the verification of real-time data transmission in the actual environment.