Study Of Power Line Communication Technology Based On The SOQPSK

With the fast development of power industry, the construction of low- voltage distribution network has already been completed in urban, rural and remote mountainous areas. Therefore, as a transmission medium, the low- voltage power line communication has many advantages, such as easy access, no wiring, quick construction and wide distribution, so it receives widespread attention in the intelligent meter reading, smart home, internet broadband access, and it is one of the best options to solve the ‘last kilometer' problem. Due to the heavy time-varying and the interference characteristics of the communication channel, some thorny problems need to be solved in the power line communication. In order to transmit the high-speed data over the power line, the cha nnel of the low-voltage power line should be analyzed and estimated. A reasonalble s ignal encoding and modulation technology also needed to be adopted to resist the channel noise and attenuation of interference.In this paper, the characteristics of low voltage power line channel, such as impedance, noise and attenuation, are studied and analyzed, then the simulation of the low voltage power line channel model and noise model is provided. This paper analyzes the theory of Shaping Quadrature Phase Shift Keying Modulation(SOQPSK) in detail, and compares recursive/nonrescursive SOQPSK by simulation. Then, an improved SOQPSK modulation method is proposed, and a power line communication simulation system based on SOQPSK is established. The simulation results demonstrate that the improved SOQPSK modulation has many advantages at anti- inference, spectral efficiency and anti- nonlinear characteristics, which showes good application value in future power line communication system. To further improve the performance of power line communication, we are inspired from the method of the cognitive radio and design a scheme of power line channel sensing and access based on Partially Observable Markov Decision Process(POMDP) model. By simulation, the results show that the scheme could improve the anti- interference ability and channel throughput of power line co mmunication.