Extra-large massive multiple-input multiple-output (XL-MIMO) systems is a new concept, where spatial non-stationarities allow activate a high number of user equipments (UEs). This letter focuses on a grant-based random access (RA) approach in the novel XL-MIMO channel scenarios. Modifications in the classical Strongest User Collision Resolution (SUCRe) protocol have been aggregated to explore the visibility regions (VRs) overlapping in XL-MIMO. The proposed grant-based RA protocol takes advantage of this new degree of freedom for improving the number of access attempts and accepted UEs. As a result, the proposed grant-based protocol for XL-MIMO systems is capable of reducing latency in the pilot allocation step.

中文翻译：

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超大型Massive MIMO系统中基于授权的随机接入协议

超大型大规模多输入多输出 (XL-MIMO) 系统是一个新概念，其中空间非平稳性允许激活大量用户设备 (UE)。这封信重点介绍了新型 XL-MIMO 信道场景中基于授权的随机接入 (RA) 方法。对经典的最强用户冲突解决 (SUCRe) 协议的修改进行了汇总，以探索 XL-MIMO 中重叠的可见性区域 (VR)。提议的基于授权的 RA 协议利用这种新的自由度来提高接入尝试和接受的 UE 的数量。因此，为 XL-MIMO 系统提出的基于授权的协议能够减少导频分配步骤中的延迟。