面向直连设备到卫星通信的采用DFT-s-OFDM的激进非正交传输
Aggressive Non-Orthogonal Transmission with DFT-s-OFDM for Direct Device-to-Satellite Communications
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中文总结 AI 辅助
本文针对D2S通信的SE瓶颈与UE功率效率问题，提出结合激进非正交传输与DFT-s-OFDM的新型接收机，仿真显示其SE与PAPR性能均优于基线及现有方案。
中文摘要 AI 辅助
直连设备到卫星（D2S）通信可实现未修改的用户设备（UE）的全球连接，将覆盖范围扩展到地面网络之外，但实现这一愿景面临根本性挑战：严重的路径损耗和有限的UE发射功率使得上行链路信噪比远低于地面网络标准，同时合适的频谱资源仍十分稀缺。这些约束共同造成了频谱效率（SE）瓶颈，在此情况下，UE功率放大器的效率至关重要，其共同决定了发射功率和电池寿命。为提升UE侧功率效率，3GPP已采用离散傅里叶变换扩展正交频分复用（DFT-s-OFDM）作为可选上行链路波形，利用其相对于OFDM显著更低的峰均功率比（PAPR）。为打破SE瓶颈，本文表明激进非正交传输（即并发用户数超过接收天线数2倍以上）可释放大量未被利用的容量增益。然而，要实现这些增益，需要尚未开发的接收机架构。DFT-s-OFDM加剧了这一难题：DFT扩展使信号分量在子载波间耦合，增大了检测问题的有效维度。本文提出一种新型接收机设计，同时利用激进非正交传输的SE增益和DFT-s-OFDM的功率效率优势。在考虑实际信道估计误差和高移动性多普勒的仿真中，该方案实现了基线2倍的SE，在复杂度仅为近期非线性MIMO接收机15%的情况下，SE超出后者40%，且相对于DFT-s-OFDM MIMO降低PAPR达6 dB，相对于OFDM降低达11 dB。
英文摘要
Direct Device-to-Satellite (D2S) communications promise global connectivity to unmodified user equipment (UE), extending coverage beyond terrestrial networks. Realizing this promise is fundamentally challenging: severe path loss and limited UE transmit power push uplink SNRs far below terrestrial norms, while suitable spectrum remains scarce. Together, these constraints impose a spectral-efficiency (SE) bottleneck, and under such conditions the efficiency of the UE power amplifier becomes critical, jointly governing transmit power and battery life. To improve UE-side power efficiency, 3GPP has adopted Discrete Fourier Transform-spread OFDM (DFT-s-OFDM) as an optional uplink waveform, exploiting its substantially lower Peak-to-Average Power Ratio (PAPR) relative to OFDM. To break the SE bottleneck, we show that aggressive non-orthogonal transmission, in which the number of concurrent users exceeds the number of receive antennas by more than 2x, can unlock substantial capacity gains that remain entirely unexploited. Realising these gains, however, requires receiver architectures that, to the best of our knowledge, have not yet been developed. DFT-s-OFDM intensifies the difficulty: the DFT spreading couples signal components across subcarriers, inflating the effective dimensionality of the detection problem. We address both challenges with a novel receiver design that jointly exploits the SE gains of aggressive non-orthogonal transmission and the power-efficiency benefits of DFT-s-OFDM. Simulations under realistic channel-estimation errors and high-mobility Doppler show that the proposed scheme achieves 2x the SE of baseline, surpasses recent nonlinear MIMO receivers by 40% at 15% of their complexity, and reduces PAPR by up to 6 dB relative to DFT-s-OFDM MIMO and 11 dB relative to OFDM.
