Optimum receiver of coded M-FSK modulation for power line communications

Combining Multiple Frequency Shift Keying (M-FSK) modulation and permutation codes has been used to make power line communications (PLC) robust against narrowband noise disturbance and impulse noise. However, the conventional hard decoding of permutation codes is lacking of stability in frequency selective channel since it depends on threshold comparison with every M-FSK envelope detector. In this paper, authors propose a permutation decoding process based on soft demodulator output. Using this innovative scheme, the decoder performs better error correction capability and presents a gain up to 3 dB over hard decoding for same PLC channel conditions.