Development of Improved Nyquist Filters with piecewise linear frequency characteristics

In this paper we present a design concept for a new family of Improved Nyquist Filters (INFs). The filters performance, in terms of error probability, depends on the presence of symbol timing errors for the same values of the excess bandwidth, timing jitter, signal to noise ratio and number of interfering pulses. The characteristic property of the new family of inter-symbol interference (ISI) free pulses generated by the proposed filters is the asymptotic decay rate of t^-1 and t^-2. The proposed design concept to construct Nyquist filters is based on a piece-wise frequency characteristic, composed of two or three linear pieces in the transition region with different slopes. Analytical and simulation results are presented to show that improvements can be achieved as compared to previously reported pulses taken as references.