Design And Implementation On Key Technologies Of SEFDM Communication System

In modern society,people’s demand for communication services is getting stronger and stronger,but the frequency band resources of communication systems are limited.Therefore,how to improve the frequency band utilization of the communication system has become the focus of scholars’ research.Currently mainstream technologies such as Orthogonal Frequency Division Multiplexing(OFDM)can effectively combat inter-sub-carrier interference and inter-symbol interference because of the orthogonality between sub-carriers.But it is precisely because the orthogonality is to be maintained,the only way to improve the spectral efficiency is to increase the modulation order,which will lead to a decrease in the bit error rate performance of the system.Therefore,in recent years,the research on improving spectral efficiency has gradually turned to non-orthogonal transmission technology.High spectral efficiency frequency division multiplexing(SEFDM)technology is a non-orthogonal transmission system,it is based on the multi-carrier mode of the OFDM system.By reducing the interval between the sub-carriers,the orthogonality between the sub-carriers is relaxed,and the spectral efficiency is improved.However,it is precisely because the orthogonality of the sub-carriers is destroyed that compared with the OFDM technology,the SEFDM system will cause severe inter-sub-carrier interference(ICI),which brings many difficulties to the design and implementation of the SEFDM communication system.The purpose of this paper is to balance the performance and complexity of the system,to simulate and design the key technical part of the SEFDM communication system,then make an FPGA implementation of system.The main tasks as follows:1.The basic theory of SEFDM signal is analyzed by OFDM technology,and the advantages and difficulties of SEFDM technology are shown.On this basis,several key technical parts in the SEFDM system are introduced,including signal generation and preliminary demodulation,channel estimation and equalization,and signal detection.It lays the foundation for the design and implementation of the system.For the self-interference problem of SEFDM system,the importance of the signal detection part is emphasized,and several classical detection algorithms of SEFDM signals are introduced,including TSVD algorithm,ID algorithm,SD algorithm,FSD algorithm and their hybrid algorithm.etc.It is found that in the scenario of large system scale or high degree of compression,the detection algorithm with lower complexity has poor performance of bit error rate by Matlab simulation and analysis,which is difficult to meet the actual communication needs,while the detection algorithm with excellent performance is There is also the problem of high computational complexity,which makes the algorithm difficult to implement on some hardware platforms.2.Aiming at the shortcomings of traditional detection algorithms,two SEFDM signal detection algorithms with low complexity and excellent performance are introduced: the detection algorithm based on Turbo equalization and the detection algorithm based on ICI compensation.Based on these two algorithms,combined with Turbo coding,an improved SEFDM signal detection algorithm is proposed.The results of comparative analysis and Matlab simulation show that the improved algorithm not only further reduces the computational complexity,but also solves the problem that the original algorithm requires multiple iterations,which means the algorithm is simple to implement in hardware.At the same time,it can provide excellent bit error rate performance.3.The structure of the transceiver ends of the system is built by the introduction and analysis of the key technical parts of the SEFDM system,the overall scheme of the baseband part of the physical layer of the system is designed,and the correctness of the scheme is verified by simulation.The hardware implementation in this paper uses the Vivado design environment and FPGA platform,and finally completes the baseband system design,development and preliminary verification.This paper focuses on the implementation details of several key modules,including port definitions,main processes,etc.,and verifies the correctness of the hardware solution through simulation waveforms.