Research And Implementation On Single Carrier Frequency Domain Equalization For LEO Satellite Mobile Communication

Satellite communication system is the mainstays of Space-Earth Integration Information Network Platform(SEIINP). Researchers’ attention to satellite communications has reached an unprecedented level. The research on the transmission technology of the low earth orbit(LEO) satellite mobile communication, which is an important part of satellite communication, has been a hot issue. Multipath fading and Doppler frequency shift are the issues of LEO satellite mobile communication channel. When the communication is the high speed transmission, the multipath effect will bring the frequency selective fading. In order to overcome the effect of multipath effects in the LEO satellite mobile communication down link, many scholars put forward that the application of OFDM technology can solve the issues. But the peak average power ratio(PAPR) of OFDM is too high to solve the problem. Single carrier frequency domain equalization(SC-FDE) technology can effectively avoid the defects of OFDM and meanwhile take into account the advantages of it. Therefore, this paper proposes the application of SC-FDE technology in LEO satellite communication. In this paper, we have studied the related equalization algorithm of and improve the optimization. Also, the paper implements one of the equalization algorithms in hardware to validate it.Firstly, this paper mainly discusses the background of the subject and the purpose and the significance of the research. Secondly, this paper explains the multipath channel model and the characteristics of the LEO satellite mobile communication in detail. Meanwhile, the transmission model of single carrier frequency domain equalization system is also introduced in detail. In this paper, the channel estimation is based on the least square(LS) algorithm. Thirdly, this paper mainly studies several algorithms of SC-FDE, including the traditional linear equalization algorithms that are zero forcing(ZF) equalization algorithm and minimum mean square error(MMSE) equalization algorithm. And this paper compares the performance of the two. In order to improve the applicability of equalization, an adaptive equalization algorithm based on ZF equalization is studied. The simulation results show that the bit error ratio(BER) performance of the system is significantly improved at the condition of high signal to noise ratio(SNR).Then, this paper studies the iterative block decision feedback equalization(IBDFE) algorithm, which is the typical representative of the nonlinear equalization algorithm. In order to reduce the complexity of the IBDFE, this paper proposes an improved IBDFE algorithm. And the performance of the improved algorithm and the traditional algorithm of IBDFE is compared and analyzed. The simulation results show that the improved algorithm can decrease the system performance to a certain extent. But the BER performance of improved algorithm is still better than MMSE algorithm. One obvious advantage is that the improved IBDFE algorithm greatly reduces the computational complexity compared with the traditional one. Finally, this paper gives the implementation scheme of ZF equalization to SC-FDE system on engineering application. And the equalization processing module of the receiver is designed and implemented to lay the foundation for the further performance of the algorithm..