Study Research On Key Technologies For WOFDM In Low-Voltage Power-Line

Recent years, with the continuous development of communication technology, data transmission has become the focus of attention through the current coverage of a wide variety of power line. Earlier communication technologies could not meet the demand for high-performance transmission any more, OFDM technology has been classified as the main power line transmission technology, but for the low-voltage power line channel environment which is worse than wireless channel, OFDM technology need to be improved in some aspects, such as the addition of cyclic prefix make OFDM reduce the bandwidth utilization, so domestic and foreign scholars continued to study the new multi-carrier communications systems, wavelet transform has become the focus of the study with more powerful signal processing than Fourier transform. However, wavelet transform is in reserching stage, some key problems still need to be resolved. For example, how to select the optimal wavelet bases in different environments channel, how to achieve the technology with hardware and so on.The improved multi-carrier communication system WOFDM was deeply researched and analyzed in this paper. The main content is below: (1) Compared and analyzed variety of modulation techniques in low-voltage power line, designed automatic meter reading of power-line networking system based on OFDM. (2) Analyzed the theoretical basis of WOFDM system deeply, and researched the differences between OFDM system and WOFDM system, and simulated the performance of the two system based on different channel environments. (3) Studyed the feasibility of wavelet transform discrete applies to WOFDM system, and proved that wavelet transform was superior to Fourier transform in multi-carrier communication from the perspective of signal space orthogonal decomposition. (4) Considering the difficulty of choosing wavelet bases, analyzed and simulated the performance of WOFDM system based on different orthogonal wavelet comprehensively. It was to lay a theoretical foundation for the future of the adaptive WOFDM system (5) Multi-path of WOFDM system can choose different carrier modulation. So designed and achieved a variety of modulation techniques based on FPGA, and proved the correctness of designs by experiment. It was to lay a foundation for the future hardware implementation of the adaptive WOFDM system. (6)Achieved hamming code and decode of the WOFDM system with FPGA. (7) Existing problems and the further research direction of WOFDM system were discussed. The Matlab simulation results show that the WOFDM system has superior performance than the traditional OFDM system.