Research And Implementation Of Channel Detection And Estimation For LPLC And Its Adaptive Rate Transmission

Low-voltage power line communication is a way of communication using of the existing powerline network for data transmission. As its small line investment and convenient connection, LPLC has widely application foreground. With the development of communication technology and the adaptive technology, LPLC obtains the rapid development and towards the practical direction at the same time, it has become a current hot research topic in the field of science and technology. But compared with the high voltage power line communication, the LPLC has its inherent drawback, outstanding performance in the bad channel conditions, big time-varying, loading more, the small line impedance, signal attenuation, sending a limited power and the serious noise. Designing a communicaiton system suitable for the environment of the channel is a key problem of the low voltage power line communication. In the view of the low voltage power line channel characteristics, this topic research the key communication technology and design an adaptive rate transmission system to realize the reliable and efficient communication.Through the analysis of traditional 2FSK demodulation method, this paper realizes the 2FSK demodulation of the communication system based on DSTFT by using spectral estimation and time-frequency analysis. According to the low voltage power line channel characteristics influence on communication system, we research channel estimation method, and put forward SNR estimation algorithm based on DSTFT in view of the frequence domain demodulation, providing demodulation parameters for the data consolidation of adaptive rate transmission system. The design of the adaptive rate transmission system mainly includes the CRC check wrong words, the error correction code, HARQ technology, data consolidation and adaptive speed synchronous adjustment algorithm. At the same time, we build adaptive rate transmission system model by using MATLAB to analysis of system performance.This paper use the TI company’s high-performance 32-bit fixed point DSP chip TMS320F2812 as the core control platform, and realize the core algorithm of various modules in LPLC adaptive rate transmission system by programming. The core algorithm includes 2FSK modulation,2FSK demodulation based on DSTFT, serial transceiver module, CRC check wrong words, the encoding and decoding of hamming code, HARQ feedback control, data merge, and adaptive speed synchronous adjustment. At the same time, we design the corresponding peripheral circuits to achieve complete point-to-point low voltage power line communication system. The circuits include sending a power amplifier, coupling, resonant filter and received signal amplifying circuit.Finally, this paper sets up low voltage power line communication experimental test platform. Through the different channel environment, we test and analyze the performance of adaptive rate transmission system under the condition of different system parameters. The experimental results show that the LPLC adaptive rate transmission system designed by this paper can effectively improve the anti-interference ability of the communication system, it also can improve the reliability of communication under bad low voltage power line channel environment.