Low Complexity Turbo Equalisation for Power Line Communications

Due to the highly dispersive nature of the power line channel, there has been a strong trend towards the use of orthogonal frequency division multiplexing (OFDM) modulation for wideband power line communications (PLC). However, OFDM modulation has the drawbacks of high peak-to-average power ratio and increased sensitivity to carrier synchronisation errors. On the other hand, single-carrier (SC) modulation techniques do not suffer from these problems and they are widely used in low-rate narrowband PLC. For broadband PLC, however, the strong intersymbol interference (ISI) introduced by the power line channel calls for the use of powerful coding and equalisation techniques, such as turbo coding/equalisation. In this paper, we investigate the performance of the so-called soft interference cancellers (SIC) techniques for turbo equalisation (TE) in PLC applications. The results of simulations over powerline channels with different amounts of memory show that, after performing some number of iterations, the SIC-based TE scheme outperforms a COFDM system that uses the same turbo code, over the entire range of SNR values.