Analysis and Design of LDPC Codes for FTN Signaling with Finite Number of Turbo Iterations

This paper contains a performance analysis of Faster than Nyquist (FTN) signaling schemes that employ low-density parity-check (LDPC) codes, trellis-based detector and turbo equalization decoding principle. Based on EXIT charts analysis, we provide a numerical upper bound on achievable information rate (AIR) of FTN communication systems with identically and uniformly distributed (i.u.d.) inputs and finite number of turbo decoding iterations. Additionally, we derive a tighter conjectured upper bound on AIR and demonstrate its usefulness by showing that it is possible to design randomly constructed LDPC codes that operate within 0.7 dB of the proposed bound.