Research On Synchronization And Receiver Of New Broadband Multi-Carrier Systems

Orthogonal Frequency Division Multiplexing(OFDM),with its excellent transmission performance and simple implementation,has been widely used in many communication standards including 4G Long Term Evolution(LTE)and IEEE 802.11.However,OFDM also has the disadvantages of high out-of-band emissions and sensitivity to time-frequency variations.The fifth-generation mobile communication system(5G)will make greater use of existing spectrum resources.Therefore,it is necessary to introduce more flexible waveform configurations to meet the needs of enhanced mobile broadband(eMBB),ultra-high reliability and low-latency Extended connection(URLLC),massive machine-type communication(mMTC),which are three kinds of application scenarios in 5G.And now filtered-OFDM(f-OFDM),Universal Filtered Multicarrier(UFMC)and windowed OFDM.(W-OFDM)has been widely studied as the new multi-carrier waveform.In this paper we studies these three kinds of waveforms,and focuse on the Peak to Average Power Ratio(PAPR)reduction technology,synchronization technology of new multi-carrier systems,and builds the hardware test platform based on Software Defined Radio(SDR).The first chapter outlines the goals of 5G and the requirements for waveforms,introduces the state of the art of several candidate waveforms,the research content and structure of this paper.The second chapter introduces the system models of f-OFDM,UFMC and W-OFDM in detail,and compares the spectrum performance and BER performance of the three waveforms.The results show that in the scenario of single user,the BER performance of the new multi-carrier systems degrades due to the filtering and windowing,compared to conventional cyclic-prefix based OFDM system.In multi-user scenarios,f-OFDM provides the best BER performance due to its lowest out-of-band attenuation,improved by 3dB over OFDM.The third chapter studies the PAPR performance of the new multi-carrier system.PAPR can be measured by Complementary Cumulative Distribution Fuction(CCDF).This chapter firstly analyzes and derives the CCDF theoretical curve of f-OFDM,Secondly propose three PAPR reduction algorithms for new multi-carrier systems,such as Iterative Clipping And Filtering,Iterative Crest Factor Reduction and Clipping AndWindowing.The simulation results show that these three methods successfully reduce the PAPR of the new multi-carrier system.The iterative crest factor reduction is most suitable for the filter-based multi-carrier system.The PAPR performance and BER performance of W-OFDM based on the clipping and windowing are better than f-OFDM and UFMC,improved by 5dB over OFDM in PAPR performance.The fourth chapter studies the synchronization technology of the new multi-carrier system.This chapter firstly derives the influence of time and frequency offset on new multi-carrier system,and proves that the effect of time-frequency offset on f-OFDM is almost the same as that of OFDM,but UFMC can tolerate less time-frequency deviation than f-OFDM.Secondly,a new style of synchronization pilot and a new synchronization algorithm are designed for the new multi-carrier system.In addition,the performance of the new synchronization algorithm is simulated under three scenarios: extended pedestrian channel model,extended vehicle channel model,and extended urban channel model.The simulation results show that the new synchronization algorithm successfully estimates the time-frequency offset and can adapt to more application scenarios than the original algorithm.Chapter 5 focuses on hardware verification of the new multi-carrier system transceiver structure,PAPR reduction technology,and synchronization algorithm introduced in the previous chapter.Based on the Universal Software Radio Peripheral(USRP),the hardware test platform demonstrate the communication process of the new broadband multi-carrier system and prototype verification of the new multi-carrier system.The last chapter summarizes the work of this paper,and discusses the problems of the new multi-carrier system and the next research direction.