Adaptive permutation coded differential OFDM system for power line communications

With a view to improving the capacity of the differential OFDM modulation scheme, specified in the narrowband power line communications (PLC) standards, in combating PLC channel associated noise, we hereby propose a permutation coded modulation scheme, which employs the hybridization of two kinds of DPSK (differential phase shift keying) modulations in an adaptive manner. The algorithm for deducing the encoded information from the hybridized modulations is described as well. This scheme is simulated and its performance is compared with a recently reported differential quinary PSK-OFDM system in the literature, whose behaviour has been shown to be better than the conventional permutation coded D8PSK-OFDM scheme at lower signal power to noise spectral density. Due to the simplicity in its encoding and decoding algorithms, this scheme is a good candidate for a number of low speed telemetry signaling in smart grids.