Research Of Channel Encode Of Nrrrow-Band Power Line Commuincation

Narrowband power line communication means transmission band at3～500kHz, whose communication channel is the power line. Now China has not yet established a unified power line communications standard, power line carrier chip also varied, but their rate, made in in-home, usually less than many of chips from abroad. The main work of this paper is to design the narrowband power line communications systems based OFDM, including selecting about the band, the number of subcarriers and the way of the modulating model, also including noise power spectrum estimation and dynamic spectrum allocation techniques.This article describes the main principles of the OFDM, and RS convolutional codes, Turbo codes, LDPC codes are defined and its main encoding, decoding algorithm; defines the parameters of each modulation of the power line communication system and method carried out; achieve a real-time estimation to the spectrum of power line noise power from its subchannels, and thus to select modulation mode of the suncarriers and t allocate the power of these subcarriers according estimation.For frequency-selective properties of power line channel, refer to PLC-G3, P1901, PRIME, Homeplug and so on, the relevant parameters of these three methods, of channel encode, including RS convolutional codes, Turbo codes and LDPC codes. By comparing with these three codes’s performance on the power line commuincaion which have desiened, lead to the conclusion:the Turbo code, have better error resilience, is more suitable for of forward error correction of the power line communication system in our country.