AI 中文总结
针对低地球轨道卫星网络大规模连接中现有方案性能不佳的问题，提出迭代残差反馈多测量向量近似消息传递算法，利用多域协同稀疏性及残差反馈机制，并设计数据调制方案，提升了检测精度等性能。
AI 中文摘要
免授权随机接入因其减少接入延迟而有望应用于低地球轨道卫星互联网。然而，现有方案在大规模连接场景中性能不佳。为此，我们首先提出一种迭代残差反馈多测量向量近似消息传递算法，利用空间 - 频率和角度 - 延迟域中的多域协同稀疏性交替进行活跃用户终端检测和信道估计，并引入残差反馈机制抑制误差积累。此外，传统数据检测方法在活跃用户终端空间距离近或数量超过卫星接收天线时性能显著下降，我们设计了联合空间 - 频率多域扩频的数据调制方案来缓解此问题。仿真结果表明，该方案在活跃用户终端检测精度、信道估计精度和误码率方面显著优于现有免授权方法，尤其在低有效导频长度和实际信噪比条件下。
英文摘要
Grant-Free (GF) random access is promising for low Earth orbit satellite Internet due to its reduced access latency. However, existing schemes suffer from poor performance in massive connectivity scenarios. To address this challenge, we firstly propose an iterative residual feedback multi-measurement vector approximate message passing algorithm. This algorithm leverages multi-domain synergistic sparsity in the spatial-frequency and angular-delay domains to alternately perform active user terminal detection (AUD) and channel estimation (CE). Additionally, a residual feedback mechanism is incorporated to suppress error accumulation, thereby enhancing AUD performance. Furthermore, conventional data detection (DD) methods significantly degrade when active user terminals are spatially close or outnumber the satellite's receive antennas, making the demodulation problem rank-deficient or underdetermined. To mitigate this, we design a data modulation scheme via joint spatial-frequency multi-domain spreading, which utilizes observations from both spatial and frequency domains to facilitate multi-domain DD. Simulation results demonstrate that the proposed scheme significantly outperforms existing GF methods in terms of AUD accuracy, CE precision, and bit error rate, especially under conditions of low effective pilot length and practical signal-to-noise ratios.
