用注意力机制解决大规模无小区多天线系统中的导频污染问题,提升功率控制效率。
Pilot Contamination Aware Transformer for Downlink Power Control in Cell-Free Massive MIMO Networks
- 引入导频分配信息的自注意力结构,显式建模导频污染影响
- 在大规模网络中实现与优化算法相当的频谱效率公平性
- 支持用户数动态变化,无需重训练,计算效率显著优于传统方法
基于学习的下行功率控制为无小区大规模多输入多输出(CFmMIMO)系统提供了替代传统迭代优化算法的可行方案,后者因在线迭代步骤而计算开销大。现有学习方法常忽略信道数据内在结构及导频分配信息,导致在大规模、多用户场景下性能不佳。本文提出导频污染感知功率控制(PAPC)Transformer神经网络,将导频分配数据融入网络,有效应对导频污染场景。PAPC采用自定义掩码的注意力机制,利用信道结构与导频信息;架构包含定制预处理与后处理阶段,实现高效特征提取并满足功率约束。在无监督学习框架下训练,评估显示其频谱效率公平性与加速近端梯度(APG)算法相当,但计算效率大幅提升。仿真表明,相比缺乏导频信息的全连接网络(FCNs),PAPC性能更优;具备扩展至大规模CFmMIMO网络的能力,且计算效率远超APG。此外,通过填充技术,PAPC可适应动态用户数变化,无需重新训练。
原文摘要 · Abstract (English)
Learning-based downlink power control in cell-free massive multiple-input multiple-output (CFmMIMO) systems offers a promising alternative to conventional iterative optimization algorithms, which are computationally intensive due to online iterative steps. Existing learning-based methods, however, often fail to exploit the intrinsic structure of channel data and neglect pilot allocation information, leading to suboptimal performance, especially in large-scale networks with many users. This paper introduces the pilot contamination-aware power control (PAPC) transformer neural network, a novel approach that integrates pilot allocation data into the network, effectively handling pilot contamination scenarios. PAPC employs the attention mechanism with a custom masking technique to utilize structural information and pilot data. The architecture includes tailored preprocessing and post-processing stages for efficient feature extraction and adherence to power constraints. Trained in an unsupervised learning framework, PAPC is evaluated against the accelerated proximal gradient (APG) algorithm, showing comparable spectral efficiency fairness performance while significantly improving computational efficiency. Simulations demonstrate PAPC's superior performance over fully connected networks (FCNs) that lack pilot information, its scalability to large-scale CFmMIMO networks, and its computational efficiency improvement over APG. Additionally, by employing padding techniques, PAPC adapts to the dynamically varying number of users without retraining.
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