太赫兹频段中采用低分辨率模数转换器与空间过采样实现高阶星座传输的检测方案
Detection Schemes with Low-Resolution ADCs and Spatial Oversampling for Transmission with Higher-Order Constellations in the Terahertz Band
AI总结：
本文研究太赫兹SIMO系统中低分辨率ADC与空间过采样下的检测方案，提出最优及次优检测器，并通过星座优化显著降低高阶QAM传输的符号错误率。
摘要：
在本文中，我们研究了接收端采用低分辨率均匀量化与空间过采样的太赫兹（THz）通信，其对应于单输入多输出（SIMO）传输。我们通过保持模数转换器（ADC）功耗恒定，对不同ADC参数化方案进行了公平比较。在此，我们研究了具有不同过采样因子的1比特、2比特和3比特量化。我们解析地计算了检测变量的统计特性，并针对任意量化分辨率提出了最优检测方案和几种次优检测方案。随后，我们评估了不同检测器在16进制和64进制正交幅度调制（QAM）下的符号错误率（SER）。结果表明，当星座规模大于量化电平数时，与最优检测器相比，次优检测器的性能下降明显。此外，在低信噪比（SNR）条件下，即使采用高阶星座，1比特量化也分别优于2比特和3比特量化。我们通过蒙特卡洛仿真验证了解析结果。我们同时考虑了纯视距（LoS）信道和更符合实际的室内太赫兹信道模型。然后，我们针对1比特和2比特量化，以符号错误率为目标优化了输入信号星座。研究结果为任意量化分辨率下高阶星座的优化提供了见解，并表明通过适当放置星座点可以显著降低最小符号错误率。
英文摘要：
In this work, we consider Terahertz (THz) communications with low-resolution uniform quantization and spatial oversampling at the receiver side, corresponding to a single-input multiple-output (SIMO) transmission. We fairly compare different analog-to-digital converter (ADC) parametrizations by keeping the ADC power consumption constant. Here, 1-, 2-, and 3-bit quantization is investigated with different oversampling factors. We analytically compute the statistics of the detection variable, and we propose the optimal and several suboptimal detection schemes for arbitrary quantization resolutions. Then, we evaluate the symbol error rate (SER) of the different detectors for 16- and 64-ary quadrature amplitude modulation (QAM). The results indicate that there is a noticeable performance degradation of the suboptimal detectors compared to the optimal detector when the constellation size is larger than the number of quantization levels. Furthermore, at low signal-to-noise ratios (SNRs), 1-bit quantization outperforms 2- and 3-bit quantization, respectively, even when employing higher-order constellations. We confirm our analytical results by Monte Carlo simulations. Both a pure line-of-sight (LoS) and a more realistically modeled indoor THz channel are considered. Then, we optimize the input signal constellation with respect to SER for 1- and 2-bit quantization. The results give insights for optimizing higher-order constellations for arbitrary quantization resolutions and show that the minimum SER can be lowered significantly by appropriately placing the constellation points.
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