Analysis of a FTN Multicarrier System: Interference Mitigation Based on Tight Gabor Frames

Abstract

Cognitive radio applications require flexible waveforms to overcome challenges such as opportunistic spectrum allocation. In this context, filtered multicarrier modulations are particularly justified to fit time-frequency characteristics of the channel. In our theoretical framework, a multicarrier signal is described as a Gabor family the coefficients of which are the symbols to be transmitted and the generators are the time-frequency shifted pulse shapes to be used. In this article, we consider non-rectangular pulse shapes and an increased signaling density such that inter-pulse interference is unavoidable. Such an interference is minimized when using a tight Gabor frame. We show that, in this case, it can be approximated as an additive Gaussian noise, allowing us to compute theoretical bit-error-probability. This result allows to predict the convergence of a coded system using iterative decoding. We also study the relevancy of such a system in an interference cancellation context.

Keywords

• multicarrier modulations
• faster-than-Nyquist signaling
• linear system
• optimal pulse-shapes
• Gabor frames
• interference analysis
• interference cancellation
• low-density parity check codes