  In this paper, we investigate the detection problem of binary
faster-than-Nyquist (FTN) signaling and propose a novel sequence estimation
technique that exploits its special structure. In particular, the proposed
sequence estimation technique is based on sphere decoding (SD) and exploits the
following two characteristics about the FTN detection problem: 1) the cor-
relation between the noise samples after the receiver matched filter, and 2)
the structure of the intersymbol interference (ISI) matrix. Simulation results
show that the proposed SD-based sequence estimation (SDSE) achieves the optimal
performance of the maximum likelihood sequence estimation (MLSE) at reduced
computational complexity. This paper demonstrates that FTN signaling has the
great potential of increasing the data rate and spectral efficiency
substantially, when compared to Nyquist signaling, for the same bit-error-rate
(BER) and signal-to-noise ratio (SNR).
