Low-complexity graph-based turbo equalisation for single-carrier and multi-carrier FTN signalling

The authors propose a novel turbo detection scheme based on the factor graph (FG) serial-schedule belief propagation equalisation algorithm with low complexity for single-carrier faster-than-Nyquist (SC-FTN) and multi-carrier FTN (MC-FTN) signalling. In this work, the additive white Gaussian noise channel and multi-path fading channels are both considered. The iterative FG-based equalisation algorithm can deal with severe intersymbol interference and intercarrier interference introduced by the generation of SC and MC-FTN signals, as well as the effect of multi-path fading. With the application of Gaussian approximation, the complexity of the proposed equalisation algorithm is significantly reduced. In the turbo detection, low-density parity check code is employed. The simulation results demonstrate that the FG-based turbo detection method can achieve satisfactory performance with low complexity.