Partial-response precoding scheme for multiple pulse-position modulation

The authors propose a partial-response precoding scheme for combating intersymbol interference that is compatible with trellis codes based on multiple pulse-position modulation. The scheme reduces the span of intersymbol interference from a possibly infinite number to two baud periods, significantly reducing the complexity of the receiver equaliser. Numerical results show that, in terms of performance and complexity, the proposed scheme compares favourably to conventional linear equalisation, block decisionfeedback equalisation and superstate maximum-likelihood sequence detection.