发表机构
Atilim University; Cankiri Karatekin University; Middle East Technical University; Ankara Yildirim Beyazit University; Izmir Bakircay University; Carleton University（阿提利姆大学; 昌克勒卡雷特金大学; 中东技术大学; 安卡拉耶尔德勒姆贝亚齐特大学; 伊兹密尔巴希切希尔大学; 卡尔顿大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究针对 BPSK、QPSK 和 16-QAM 的 FTN 信号，在 MMSE-CS 检测框架下分析其可实现信息率，发现星座阶数越高，最佳加速因子越接近奈奎斯特极限，为 FTN 信号工作点选择提供依据。
AI 中文摘要
超奈奎斯特（Faster-than-Nyquist, FTN）信号通过传输比奈奎斯特极限更密集的符号来提升频谱效率，代价是会产生额外的符号间干扰（ISI）。在本通讯中，我们研究了在发射功率约束和通用最小均方误差（MMSE）信道缩短（CS）检测框架下，BPSK、QPSK 和 16-QAM 有限字母符号的可实现信息率（AIR），并针对 BPSK 与独立的降阶 Ungerboeck Bahl-Cocke-Jelinek-Raviv（BCJR）基准进行了交叉验证。我们的结果显示出明确的趋势：低阶星座可从更激进的时间加速中获益，而高阶星座对加速的容忍度更低，其最佳频谱效率出现在更接近奈奎斯特极限的位置。在参考信噪比（SNR）为 6 dB 时，最佳加速因子从 BPSK 的 τ*≈0.65 变为 QPSK 的 0.75，再到 16-QAM 的 0.90。我们进一步证明，该趋势在编码系统中得以保留，且对检测器记忆具有鲁棒性；同时还研究了 FTN 操作对瞬时平均功率比（IAPR）的影响。总体而言，结果强调在选择 FTN 信号的工作点时应考虑星座阶数。
英文摘要
Faster-than-Nyquist (FTN) signaling can improve spectral efficiency by transmitting symbols closer together than the Nyquist limit, at the cost of additional inter-symbol interference (ISI). In this letter, we study the finite-alphabet symbol-wise achievable information rate (AIR) of FTN signaling for BPSK, QPSK, and 16-QAM under a transmit-power constraint and a common minimum mean square error (MMSE) channel-shortening (CS) detection framework, cross-validated for BPSK against an independent reduced-state Ungerboeck Bahl-Cocke-Jelinek-Raviv (BCJR) benchmark. Our results show a clear trend. Lower-order constellations can benefit from more aggressive time acceleration, while higher-order constellations become less tolerant of acceleration and achieve their best spectral efficiency closer to the Nyquist limit. At a reference signal-to-noise ratio (SNR) of 6 dB the optimum acceleration factor shifts from $τ^\star\approx0.65$ for BPSK to 0.75 for QPSK and 0.90 for 16-QAM. We further show that this trend is preserved in coded systems and remains robust to the detector memory. The impact of FTN operation on the instantaneous-to-average power ratio (IAPR) is also examined. Overall, the results highlight how constellation order should be considered when selecting the operating point for FTN signaling.
Comments5 pages, 5 figures, 2 tables. Submitted to IEEE Communications Letters
