A novel near-field transmission framework is proposed for dynamic metasurface antenna (DMA)-enabled nonorthogonal multiple access (NOMA) networks. The base station (BS) exploits the hybrid beamforming to communicate with multiple near users (NUs) and far users (FUs) using the NOMA principle. Based on this framework, two novel beamforming schemes are proposed. 1) For the case of the grouped users distributed in the same direction, a beam-steering scheme is developed. The metric of beam pattern error (BPE) is introduced for the characterization of the gap between the hybrid beamformers and the desired ideal beamformers, where a two-layer algorithm is proposed to minimize BPE by optimizing hybrid beamformers. Then, the optimal power allocation strategy is obtained to maximize the sum achievable rate of the network. 2) For the case of users randomly distributed, a beam-splitting scheme is proposed, where two subbeamformers are extracted from the single beamformer to serve different users in the same group. An alternating optimization (AO) algorithm is proposed for hybrid beamformer optimization, and the optimal power allocation is also derived. Numerical results validate that: 1) the proposed beamforming schemes exhibit superior performance compared with the existing imperfect-resolution-based beamforming scheme and 2) the communication rate of the proposed transmission framework is sensitive to the imperfect distance knowledge of NUs but not to that of FUs.

中文翻译：

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DMA-NOMA 网络的近场通信


为支持动态超表面天线（DMA）的非正交多址（NOMA）网络提出了一种新颖的近场传输框架。基站 (BS) 利用 NOMA 原理利用混合波束成形与多个近用户 (NU) 和远用户 (FU) 进行通信。基于该框架，提出了两种新颖的波束形成方案。 1）针对分组用户分布在同一方向的情况，开发了波束控制方案。引入波束方向图误差（BPE）度量来表征混合波束形成器与所需的理想波束形成器之间的差距，其中提出了一种两层算法，通过优化混合波束形成器来最小化 BPE。然后，获得最优功率分配策略以最大化网络的总可实现速率。 2）针对用户随机分布的情况，提出了一种波束分割方案，从单个波束形成器中提取两个子波束形成器来服务同一组中的不同用户。提出了一种用于混合波束形成器优化的交替优化（AO）算法，并导出了最优功率分配。数值结果验证了：1）与现有的基于不完美分辨率的波束形成方案相比，所提出的波束形成方案表现出优越的性能；2）所提出的传输框架的通信速率对NU的不完美距离知识敏感，但对NU的不完美距离知识不敏感。 FU。