Implementation Of Signal Detection Algorithm In Multi-carrier Communication System With FPGA

With the rapid development of the aviation industry, the current aviation communication system has been unable to meet the needs of aviation communication. In this paper, the mature non-continuous orthogonal frequency division multiplexing(NC-OFDM) system is applied in aviation communication system and the FPGA(Field-Programmable Gate Array) implementation of channel estimation and modulation signal demodulation in aeronautical communication is studied.The first chapter briefly introduces the aronautical communication and aeronautical channel and introduces multi carrier communication and its characteristics in detail.At last it pointed out the great significance of implementation of signal detection in multi carrier system using FPGA.The second chapter of this paper introduces the system architecture and the various modules of the system respectively.The third chapter firstly introduces the frequency linear interpolation channel estimation algorithm, which is based on least squares(LS) estimation.At the base of this channel estimation, this chapter introduces another channel estimation method, which is called Channel Estimation Method with Modified Noise.Then, we start to discuss the algorithm implementation in FPGA.The second channel estimation algorithm consists of very complex matrix operation. In order to solve this problem, two equivalent algorithms of FFT and IFFT for matrix operation is proposed.And next, this chapter introduces FPGA implementation of the Toeplitz matrix in detail. Finally, this chapter gives the Modelsim simulation diagram of the two kinds of channel estimation.The fourth chapter describes signal demodulation algorithm and its FPGA implementation of this system.In this system,we have two kinds of signals, one is the quadrature phase shift keying(QPSK) signal, the other is cyclic code shift keying(CCSK) signal.To demodulate these two signals, we use soft decision for QPSK signal and use hard decision for CCSK signal. On the basis of the analysis of the soft and hard decision algorithm of the two signal, the implementation process of FPGA is described in detail, and the corresponding ModelSim simulation diagram is given.In the fifth chapter, we put forward a test method which combines the software test and the hardware test, and test the signal detection algorithm, which fully proves the correctness of the hardware design of the signal detection algorithm.