Optimization Design And FPGA Implementation Of Ionospheric Scattering Channel Encoding,Decoding And Equalization Algorithms

With the rapid development of modern wireless communication technology,there is an increasing demand for using special communication methods to achieve large-area coverage of single site and over-the-horizon long-distance communication.Ionospheric scattering wireless communication using the scattering effect of the ionosphere can cover an area of millions of square kilometers and achieve a transmission distance of thousands of kilometers.However,the ionospheric scattering channel is complex,accompanied by strong multipath effect and time-frequency selective fading,and often works in low signal-to-noise ratio environment.Therefore,improving the anti-fading performance of ionospheric scattering communication system has become a current hot spot.Based on Single-Carrier Interleaved Frequency-Division Multiple Access(SC-IFDMA)systems,this thesis focuses on channel coding,decoding and equalization algorithms in ionospheric scattering communications.In order to improve the performance of channel coding and decoding and channel equalization algorithm,it pays attention to balance the algorithm complexity,and the SC-IFDMA ionospheric scattering communication system is developed on the FPGA hardware platform.The main research contents of this thesis are summarized as follows:Aiming at the problem of insufficient decoding performance and high encoding and decoding complexity of traditional channel coding and decoding algorithms in ionospheric scattering channel,a Packet Polar code is proposed.In the encoding step,the polarization effect of Polar code in ionospheric scattering channel is used.A Bhattacharyya parameter method based on channel estimation was proposed to construct Polar codes under ionospheric scattering channels.In the encoding and decoding step,the polarization complexity at high code length was reduced and the encoding and decoding delay was shortened by parallel packing after encoding at the encoder and parallel decoding after unpacking at the decoder.The performance of the proposed algorithm in ionospheric scattering channel was verified by simulation experiments.Aiming at the problem that the traditional linear channel equalization algorithm has low performance in ionospheric scattering channel and the nonlinear channel equalization algorithm has high complexity and is difficult to apply,an improved iterative feedback equalization algorithm was proposed,which used soft information iterative equalization to improve the equalization performance in ionospheric scattering channel.The coefficients of the feedforward filter and the feedback filter of the equalizer are kept unchanged in the iterative process,which reduces the computational complexity of the equalizer.The performance of the proposed channel equalization algorithm in ionospheric scattering channel is verified by simulation experiments.The proposed channel encoding and decoding algorithm and channel equalization algorithm are implemented on the FPGA platform,so as to develop a complete communication system suitable for ionospheric scattering channel.Through the modular design,the system is divided into sending module,synchronization module and receiving module,and the system joint debugging experiment is completed.The experimental data show that the developed scattering communication system can carry out stable data transmission,and has important application value in the field of long-distance communication.