Pilot design for channel estimation in a long-tap faster-than-Nyquist signaling transmission

摘要

Faster-than-Nyquist (FTN) techniques offer a transmission rate beyond that of Nyquist criterion without imposing bandwidth expansion. On the other hand, orthogonality among modulated pulse shapes can be destroyed because of the FTN signaling, whereupon inter-symbol interference (ISI) appears, and hence an irreducible error floor occurs. This paper presents the optimal pilot design for channel estimation in FTN signaling transmissions. By taking advantage of an additional cyclic prefix, the resultant ISI imposed by FTN signaling can be approximated by a finite-tap circulant matrix structure, which allows us to employ an efficient fast Fourier transform operation and a low pilot-ratio based frequency-domain channel estimation algorithm. Both analytical and simulation results show that the proposed design is especially beneficial for practical long-dispersion channel scenarios.