发表机构
Hamad Bin Khalifa University; University of Cambridge; Professionals for Smart Technology; Qatar University（哈马德·本·哈利法大学; 剑桥大学; 智能技术专业人士; 卡塔尔大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
针对指向误差下M-PAM星间链路，提出OHL辅助的全光再生中继，避免AF噪声累积与DF的O/E/O开销，通过理论推导与仿真验证，为低延迟指向感知全光再生中继提供设计基准。
AI 中文摘要
低轨（LEO）星座中星间流量的快速增长要求频谱效率高、低延迟的光中继。放大转发（AF）中继延迟效率高，但会传播噪声；译码转发（DF）中继可抑制噪声，但需经过光-电-光（O/E/O）转换，复杂度显著。本文针对指向误差下的多进制脉冲幅度调制（M-PAM）多跳链路，提出一种全光再生中继。并行光限幅器（OHL）阵列执行符号级判决，直接在光域再生信号电平；采用可变增益掺铒光纤放大器（EDFA）稳定功率并定义阈值稳定区域。结合指向引起的衰落、包括ASE-ASE和信号-ASE拍噪声在内的各类噪声源以及与实现相关的判决噪声，推导得到每跳符号差错率（SER）的闭式表达式；利用马尔可夫转移矩阵模型，将其扩展至任意调制阶数和跳数的端到端性能。通过对波束宽度、指向精度和阈值缩放的分析，证明该中继可实现可靠多跳运行，避免AF的噪声累积和DF的O/E/O处理开销。经蒙特卡洛仿真和数值积分验证，该框架为低延迟、感知指向的全光再生中继提供了设计基准。
英文摘要
Rapid inter-satellite traffic growth in LEO constellations demands spectrally efficient, low-latency optical relaying. While amplify and forward (AF) relays are latency-efficient, they propagate noise; conversely, decode and forward (DF) relays suppress noise but incur significant complexity via O/E/O conversion. This paper proposes an all-optical regenerative relay for M-ary pulse amplitude modulation (M-PAM) multi-hop links under pointing errors. A parallel optical hard-limiter (OHL) bank performs symbol-level discrimination, regenerating signal levels directly in the optical domain. A variable gain EDFA is employed to stabilize power and define the threshold-stable region. By incorporating pointing-induced fading, various noise sources including ASE-ASE and signal-ASE beat noise and implementation-dependent decision noise, we derive closed-form per-hop symbol error rate (SER) expressions. These are extended to end-to-end performance using a Markov transition-matrix model for arbitrary modulation order and hop count. Analysis of beamwidth, pointing accuracy, and threshold scaling demonstrates reliable multi-hop operation, avoiding both AF noise accumulation and DF O/E/O processing overhead. Verified by Monte Carlo simulations and numerical integration, this framework provides a design benchmark for low-latency, pointing-aware all-optical regenerative relaying.
