This letter proposes a novel broadband transmission technology, termed delay alignment modulation (DAM), which enables the low-complexity equalization-free single-carrier communication, yet without suffering from inter-symbol interference (ISI). The key idea of DAM is to deliberately introduce appropriate delays for information-bearing symbols at the transmitter side, so that after propagating over the time-dispersive channel, all multi-path signal components will arrive at the receiver simultaneously and constructively. We first show that by applying DAM for the basic multiple-input single-output (MISO) communication system, an ISI-free additive white Gaussian noise (AWGN) system can be obtained with the simple zero-forcing (ZF) beamforming. Furthermore, the more general DAM schemes are studied with the ISI-maximal-ratio transmission (MRT) and the ISI-minimum mean-square error (MMSE) beamforming. Simulation results are provided to show that when the channel is sparse and/or the antenna dimension is large, DAM not only resolves the notorious practical issues suffered by orthogonal frequency-division multiplexing (OFDM), such as high peak-to-average-power ratio (PAPR) and vulnerability to carrier frequency offset (CFO), but also achieves higher spectral efficiency due to the saving of guard interval overhead.

中文翻译：

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延迟对齐调制：实现无均衡单载波通信

这封信提出了一种新颖的宽带传输技术，称为延迟对齐调制（DAM），它可以实现低复杂度的无均衡单载波通信，但不会受到符号间干扰（ISI）的影响。DAM 的关键思想是在发送端故意为信息承载符号引入适当的延迟，以便在时间色散信道上传播后，所有多径信号分量将同时且建设性地到达接收端。我们首先表明，通过将 DAM 应用于基本的多输入单输出 (MISO) 通信系统，可以通过简单的迫零 (ZF) 波束形成获得无 ISI 的加性高斯白噪声 (AWGN) 系统。此外，使用 ISI 最大比传输 (MRT) 和 ISI 最小均方误差 (MMSE) 波束形成来研究更一般的 DAM 方案。