Comparison of the Spectral and Energy Efficiency of FTN Signals Based on RRC Pulses and Obtained by the Optimization Method

The paper is devoted to the study of signals obtained as a solution of the optimization task. This approach can be used in Faster-Than-Nyquist (FTN) signaling to provide extremely high transmission rates. However, an increase in transmission rate results in the strong intersymbol interference (ISI), affecting energy efficiency, especially for commonly used square-root-raised-cosine pulses. The main advantage of optimal signal is in controlled ISI level for different rates and pulse durations. We consider application of Viterbi Algorithm for optimal FTN signals reception. Using the Viterbi algorithm for receiving signals with increased duration and intersymbol interference provides close to potential BER performance, while symbol rate is higher the Nyquist limit. The paper provides the comparison of spectral and time characteristics for the optimal and root-raised-cosine pulses for different cases (pulse durations, roll-off factors).