Eigendecomposition-Precoded Faster-Than-Nyquist Signaling With Optimal Power Allocation in Frequency-Selective Fading Channels

Takumi Ishihara,Shinya Sugiura

doi:10.1109/twc.2021.3106098

Takumi Ishihara, Shinya Sugiura

Open Access

https://doi.org/10.1109/twc.2021.3106098

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Abstract

In this paper, we propose eigenvalue decomposition (EVD)-precoded faster-than-Nyquist (FTN) signaling with power allocation in a frequency-selective fading channel. More specifically, we derive the mutual information associated with the proposed FTN signaling. Then, the optimal power coefficients are calculated such that the derived mutual information is maximized. Our analytical performance results show that the proposed FTN signaling scheme achieves a higher information rate than the conventional FTN signaling scheme without relying on power allocation and the classic Nyquist signaling scheme, under the assumption that all the schemes employ a root-raised cosine shaping filter. Moreover, we derive the proposed scheme’s achievable information rate in the presence of channel estimation errors. Furthermore, our numerical simulation results for the bit error ratio performance and the power spectral density demonstrate that the proposed FTN scheme outperforms the conventional Nyquist signaling scheme without incurring any bandwidth broadening.

Highlights

The classic Nyquist criterion has played an essential role in bandlimited communication systems, having finite bandwidth 2W Hz, since it achieves intersymbol interference (ISI)-free information transmission
We introduce the concept of bit loading per symbol, where binary phase-shift keying (BPSK), quadrature PSK (QPSK), 16–quadrature amplitude modulation (QAM), 64–QAM, 256–QAM, and 1024–QAM schemes were assigned onto each activated symbol in order to achieve a target transmission rate [21]
We proposed the novel eigenvalue decomposition (EVD)-precoded FTN signaling scheme with optimal power allocation for a frequency-selective fading channel

Summary

Introduction

The classic Nyquist criterion has played an essential role in bandlimited communication systems, having finite bandwidth 2W Hz, since it achieves intersymbol interference (ISI)-free information transmission. In the Nyquist criterion, a minimum symbol interval is limited to T0 = 1/(2W ) [sec], and the achievable symbol rate is upper-bounded by 1/T0. To overcome this limitation, the concept of faster-than-Nyquist (FTN) signaling has been studied [1–7]. In FTN signaling, a symbol interval is defined by T = τ T0 (0 < τ ≤ 1), where τ is the symbol packing ratio. FTN signaling has the potential of achieving a higher transmission rate than the conventional ISI-free Nyquist counterpart without imposing any extra bandwidth. In [4], it was shown that the minimum Euclidean distance (MED) of FTN signaling is the same as that of Nyquist signaling for τ ≥ 0.802 under

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