Cell-free massive multi-input multi-output (MIMO) has recently gained much attention for its potential in shaping the landscape of sixth-generation (6G) wireless systems. This paper proposes a hierarchical network architecture tailored for cell-free massive MIMO, seamlessly integrating co-located and distributed antennas. A central base station (CBS), equipped with an antenna array, positions itself near the center of the coverage area, complemented by distributed access points spanning the periphery. The proposed architecture remarkably outperforms conventional cell-free networks, demonstrating superior sum throughput while maintaining a comparable worst-case per-user spectral efficiency. Meanwhile, the implementation cost associated with the fronthaul network is substantially diminished.

翻译：无蜂窝大规模多输入多输出（MIMO）技术因其在塑造第六代（6G）无线系统格局中的潜力而备受关注。本文提出一种专为无蜂窝大规模MIMO设计的分层网络架构，将共址天线与分布式天线无缝融合。该架构中，配备天线阵列的中心基站（CBS）位于覆盖区域中心附近，并由覆盖边缘的分布式接入点作为补充。该架构显著优于传统无蜂窝网络，在保持可比较的最坏情况用户频谱效率的同时，展现出更高的总吞吐量。此外，与前传网络相关的实现成本也大幅降低。