Phase-shifted linear partial-response modulation

Partial-response modulations are widely used for spectrum shaping and bandwidth reduction. Linear partial-response signaling (PRS) is a well-known form of linear coded modulation which was proposed by Lender (1963). Due to the lack of efficient algorithms for maximum likelihood detection the research on the subject concentrated on the simplest forms of PRS, and mainly with suboptimal detection. We analyze the properties of PRS signals generated from complex-valued functions. Those signals have not only the usual intentional intersymbol interference (ISI), but also an intentional interference between the quadrature components of the RF modulated signal. Our objective is to show how these two forms of interference should be used together. The theory presented is particularly important in the design of PRS generators for bandwidth efficient coded modulation, which are schemes with severe ISI. Furthermore, since the results are valid for intentional or non-intentional ISI, they can also be used to improve the performance of communications in non-ideal channels