On the spectral analysis of discrete-time faster-than-nyquist signaling

The main purpose of the FTN signaling is to increase data rate without using additional bandwidth or transmission power. To analyze system characteristics of the FTN-based system, such as system capacity, there have been some studies on the power spectral density (PSD) of the FTN signaling. The present study analyzes the PSD characteristics of a discrete-time model of the FTN signaling, and compares it to those of the existing work. From the analysis, we obtain the following meaningful observations: a certain relation between the truncation of the FTN data spectrum and the optimal choice of the FTN factor τ in terms of achieving the highest system capacity, and a possibility to reduce the down-sampling rate of the receivers to avoid aliasing when the bandwidth of the transmission pulse is less than the symbol rate.