The large untapped spectrum in the sub-THz allows for ultra-high throughput communication to realize many seemingly impossible applications in 6G. One of the challenges in radio communications in sub-THz is the hardware impairments. Specifically, phase noise is one key hardware impairment, which is accentuated as we increase the frequency and bandwidth. Furthermore, the modest output power of the sub-THz power amplifier demands limits on peak to average power ratio (PAPR) signal design. Single carrier frequency domain equalization (SC-FDE) waveform has been identified as a suitable candidate for sub-THz, although some challenges such as phase noise and PAPR still remain to be tackled. In this work, we design a phase noise robust, low PAPR SC-FDE waveform by geometrically shaping the constellation under practical conditions. We formulate the waveform optimization problem in its augmented Lagrangian form and use a back-propagation-inspired technique to obtain a constellation design that is numerically robust to phase noise, while maintaining a low PAPR.

翻译：亚太赫兹频段中大量未开发的频谱资源，使得实现6G中许多看似不可能的应用成为可能，从而支持超高吞吐量通信。亚太赫兹频段无线通信面临的挑战之一在于硬件损伤。具体而言，相位噪声是一项关键的硬件损伤问题，随着频率和带宽的增加而愈发突出。此外，亚太赫兹功率放大器有限的输出功率对信号设计的峰均功率比（PAPR）提出了限制。单载波频域均衡（SC-FDE）波形已被认定为适合亚太赫兹通信的候选方案，尽管如此，相位噪声和PAPR等挑战仍有待攻克。在本工作中，我们通过在实际条件下对星座进行几何整形，设计了一种对相位噪声鲁棒且具有低PAPR的SC-FDE波形。我们将波形优化问题构建为增广拉格朗日形式，并采用一种受反向传播启发的方法，获得了一种在数值上对相位噪声鲁棒且保持低PAPR的星座设计。