Research On Algorithm For Narrow-Band High Speed OFDM Power Line Communication System

Power-Line Communication (PLC) has now become one of the main communication technologies in the world, just like wireless communication and wired co-cable communication. Since power grid is the largest network in the world, PLC has its natural advantage in this area. With the rise of the smart grid and smart home construction, power line carrier communication ascendant, governments, enterprises and research institutions have invested a lot of manpower and resources to study. However, power line is not very suitable for communication, especially in narrow-band and bright-band high speed communication, impedance, attenuation of communication must become a challenge to face. Unlike wireless power line channel and coaxial cable channel, time-varying, nonlinear, time-and frequency dual selectivity. However, PLC OFDM follows the same Shannon theorem and discrete-time system models.This thesis presents the statistical analysis of the power line channel which including zero and non-zero-crossing point over the noise, impedance, attenuation characteristics that indicate the zero crossing power line channel with low noise, constant impedance, attenuation decreases. Based on these characteristics, this thesis proposes a model of power line channel suitable for NB-OFDM-PLC transmission speed, zero-crossing point of these models is to support single-carrier modulation and demodulation transfer mode on the basis of this thesis, but also with a new LDPC codec to replace the traditional Reed-Solomon code (RS) and Convolution code (CC) joint codec foundation. In this thesis, based on the G3 NB-OFDM-PLC standard, the NB-OFDM-PLC systems and the principle of mathematical models and algorithms of key technologies will be described, and specific physical realization will also be given, which is for the first time panoramic and systematic publicized inland. While, according to the power line nonlinear, large and rapid changes in the delay characteristics, this thesis has offered a unified BPSK/DBPSK/2FSK modulation and demodulation mode at the zero-crossing point of operational frequency, which could improve the success rate of communication when power line is interfered and NB-OFDM-PLC is no longer orthogonal. This thesis has also offered a new LDPC coding matrix to improve the signal/noise rate (SNR) of the system instead of the traditional RS+CC forward error correction (FEC) to improve the system signal/noise rate (SNR).According to the simulation performance, physical realization and field testing situation, the overall performance of the communication system using the new algorithm of NB-OFDM-PLC has reached the target and is much better than the system using 2FSK. In the end of this thesis is an overall description for the research areas which NB-OFDM-PLC technology should be focused in the future. Any success in these theoretical and practical research areas requires lots of material resources and manpower, the author of this thesis has also been constantly work in this field for years.