Research On Frequency Characteristics And System Performance Of Low Voltage Power Carrier Communication

During to its advantages of low cost and widely distributed circuit, power line carrier communication has bright application prospects in the smart home, remote control and other fields, which has become the iconic breakthrough of the target of the country achieving four networks convergence in future. However, the communication environment of low-voltage power line channel is quite harsh, which brings numerous difficulties for study of channel characteristics and exploitation experiment of communication product. The research work in this thesis is carried on just under this background, through research on the frequency characteristic of noise in different power line environments by site measurement and performance of PLC simulation system with different modulation technique.In this thesis, the background and significance of PLC technology were introduced firstly, and puts forward the main work contents according to the basic principle and the development history and research status both at home and abroad. And we use the low-voltage power line noise acquisition equipment to collect noise data in different power environments, then analyzes variation tendency of the power line noise amplitude with typical communication frequency and different periods. According to the phenomenon that the noise amplitude in different communication frequency are highly variable in the same area, which put forward the assumption related to noise interference frequency of electrical appliances, and verified the correctness of the assumption by analysis of experimental results.Finally, with traditional single-carrier modulation technique and OFDM modulation technology, the carrier communication systems are built in Matlab/Simulink simulation platform. In the case of different environments, different coding and different carrier modulation, we makes experimental analysis about system BER changes along with SNR and baseband transmission rate. The simulation results show that:traditional single-carrier PLC system is not suitable for signals transmission in complicated grid environment, because the noise interference in the channel is serious. BER changes of OFDM system, by contrast, both along with the SNR and the baseband transmission rate, are superior to traditional single-carrier system, especially the channel undergoes the error correction coding, the system performance has further upgrade, which demonstrated OFDM multi-carrier communication system is more appropriate for the application development in the PLC.