Research Of OFDM Receiver Key Technologies And FPGA Implementation In High Speed Mobile Environment

Orthogonal Frequency Division Multiplexing (OFDM) has been a core technology for B3Gand4G with high spectrum, resistance to multipath fading, simple channel equalization and easyhardware implementation. OFDM has been widely applied in the field of radio communication,especially in the burst transfer of the data services system. However, multipath causes signalfrequency selective fading, Doppler frequency offset causes signal time selective fading andnon-orthogonal.Compared with the single-carrier communication system, OFDM is more sensitive tosynchronization error and channel estimation error. To address these problems, the thesis mainlyfocuses on frame synchronization, ICI analysis of compensation as well as channel estimation andequalization.Firstly, the thesis studys on the capture of burst OFDM frame. Based on the analysis of thetraditional SC algorithm pros and cons, the paper introduces the Improved SC and makessimulations, the simulation results show that the stability of the Improved SC algorithm is superiorto the traditional SC algorithm, but can not achieve fine synchronization, its synchronization pointfalls within the CP. Then based on the correlation of the PN sequence, the PN sequence SCalgorithm is claimed and simulated, the simulation results show that it can achieve finesynchronization. However, the PN SC Algorithm needs to consume a large amount of multipliersfor FPGA implementation, which is not desirable. But the Improved SC algorithm uses RAM totake place of multipliers, and the burst frame is capture by FPGA simulation.Secondly, analysis and simulation of multipath Rayleigh channel are made, which gives theaffect for signal-to-noise ratio of the system produced by Doppler frequency shift. Then the analysisand comparison of the two methods based on ICI Self-Cancellation (ICI SC) modulation are made.ICI self-cancellation modulation and standard OFDM modulation algorithms are compared by thesimulation in Matlab platform.Finally, the paper analyzes LS and MMSE channel estimation algorithms based on the combpilots, then selects the LS algorithm which is easily implemented in hardware. Linear interpolation and the second-order polynomial interpolation algorithms are theoretically analyzed and simulated,the results show that the ICI self-cancellation modulation system using the LS-based linearinterpolation algorithm can achieve low BER transmission under15dB signal-to-noise ratio.Channel estimation and equalization simulation based on ICI SC demodulation using VerilogHDLunder the guidance of Matlab simulation results...