Design And Implementation Of HARQ And Combined Decoding For LPLC

With the rapidly development of PLC communication technology, it has become a hot spot in the current scientific and technological research. However, the power line channel, which has the characteristics of strong signal interference, the complex types of noise, strong signal attenuation, seriously affect the reliability of data communication. So this topic researches the error control technology applicable to PLC system, which is one of the key technologies used to ensure the low-voltage PLC system’s reliability.After analysis and comparison of modulation and demodulation technology, this paper proposes an improved algorithm of 2FSK demodulation based on DSTFT. Used MATLAB to comparison of DFT algorithm and the improved algorithm of 2FSK demodulation, verifying the effectiveness of the algorithm. The improved algorithm can make the system hardware structure simply, and improves the real-time performance of the system.Thoroughly considering the effect of noises on the PLC system, the existing error control technologies are researched and analyzed by MATLAB, including CRC code, error correction code, HARQ and combination decoding technologies, etc. It used MATLAB to model and simulate the power line communication, include error correction coding, ARQ, Combined decoding. The different combination of these technologies is studied to improve system performance. The technologies which mentioned are easy to be implemented. They have good anti-disturbance performances when applied in the following occasion: non-strict demand for delaying, low carrier frequency, low transmission rate.This paper adopts a high-performance,32-bit, fixed-point DSP chip, TMS320F2812 of the TI company as the key control platform, to implement the core algorithms of main modules in the PLC error control system, including serial transceiver, modem modules, CRC inspection code, the error correction code, HARQ and combination decoding modules, etc. Each module is designed to each independent API functions, which can be called by system’s main function. Then the appropriate peripheral circuits are designed, including the transmission of power amplifier, coupled circuit, coupled resonator filter and receiving signal amplifier circuit, etc. The whole system is simple and flexible. These key technologies are easy to be implemented, which has better anti-fading performance on the low voltage power line. In the practical applications, the error control scheme on the PLC can be designed based on the above technologies in order to achieve the low cost, easy to realize and reliable communication, according to the demand of applications and software and hardware resource allocation.A low-voltage PLC experiment system is built, and it is tested and analysis. The experimental results show that error control scheme designed for PLC can effectively resist random errors and burst errors caused by channel noises, and improve the anti-interference ability of the carrier communication system. The key error control technology provides a candidate scheme for improving the reliability of communication.