The Research Of Key Algorithm On OFDM Over Low-voltage Power Line Carrier Communication

Power Line Carrier (PLC) communication is a mean of communication using the medium-voltage or low-voltage distribution network as a medium for data transmission. It uses the existing distribution network as infrastructure, does not require any wiring, and has the low construction costs. Besides, it has a wider coverage compared to any other kind of wired networks. Due to these, the PLC communication has a unique advantage in the applications of remote meter reading automation, distribution automation, smart home, and so on. However, as a communication channel, the low-voltage power line has the inherent and unfavorable characteristics, such as a large number of load, significant attenuation, time variant, complex noise interference, and so on. Therefore, it’s necessary to choose an appropriate modulation and demodulation system for this environment to ensure the reliability of the power line carrier communication.Orthogonal Frequency Division Multiplexing (OFDM) has been more widely used in the field of power line carrier communication for its tremendous advantages, such as powerful anti-jamming capability, high spectrum efficiency, adoption of IFFT/FFT for modulation and demodulation, and so on. However, the OFDM technique also has some shortcomings. The peak to average power ratio (PAPR) is high and the requirement for synchronization system performance of the receiver is more demanding, and so on. In this paper, an OFDM communication system which is more suitable for data transmission in the low-voltage power line noise environment is designed through the research on low-voltage power line carrier communication technology based on OFDM.First, the noise characteristics of the low-voltage power line channel are analysed for the domestic power line noise environment. And mathematical models of the PLC channel noise are established considering the system application and test environment. Also the transmission characteristics of the power line channel are analysed to provide a theoretical basis for the study of the influence of power line channel on the performance of communication systems. Then, this paper analyzed the OFDM communication system, including channel estimation method、basic principle of parameter choice of OFDM and so on. Next, this paper analyses synchronization technology including following parts:① Analyzed synchronization’s influence on system;②Discuss three classical synchronization algorithm based on training sequence,analyze their advantages and disadvantages;③ Propose a low amount of calculation and low system hardware requirements algorithm;④ Through accurate synchronization probability and synchronization of mean square error analysis, validate the proposed algorithm performance is good;⑤Further optimize the proposed algorithm。After these,this paper analyses PAPR technology, First several common methods of reducing PAPR of OFDM system are compared in this paper and a better improvement Nyquist pulse shaping method is studied to reduce the PAPR of the system.Finally, this paper designed a suitable scheme on the power line communication of OFDM system, using proposed synchronization algorithm. This paper introduces the system’s design process of each module of the sender and the receiver, the use of MATLAB simulation analysis on the various modules, has carried on the simulation to the BER performance of the whole system, verify the availability of the system. Laid a theoretical foundation for the future using DSP and FPGA to implemented low voltage power line system based on OFDM.