The recent extra-large scale massive multiple-input multiple-output (XL-MIMO) systems are seen as a promising technology for providing very high data rates in high user-density scenarios. Spatial non-stationarities and visibility regions (VRs) appear across the XL-MIMO array, since its large dimension is of the same order of the distances to the user-equipments (UEs). Due to the increased density of UEs in typical applications of XL-MIMO systems and the scarcity of pilots, the design of random access (RA) protocols and scheduling algorithms become challenging. In this paper, we propose a joint RA and scheduling protocol, namely non-overlapping VR XL-MIMO (NOVR-XL) RA protocol, which takes advantage of the different VRs of the UEs for improving RA performance, besides of seeking UEs with non-overlapping VRs to be scheduled in the same payload data pilot (PDP) resource. Our results reveal that the proposed scheme achieves significant gains in terms of sum-rate compared with traditional RA schemes, as well as reducing access latency and improving connectivity performance as a whole.

中文翻译：

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探索 XL-MIMO 随机接入和调度中的非重叠可见性区域


最近的超大规模大规模多输入多输出（XL-MIMO）系统被视为一种有前途的技术，可以在高用户密度场景中提供非常高的数据速率。空间非平稳性和可见区域 (VR) 出现在 XL-MIMO 阵列中，因为其大尺寸与到用户设备 (UE) 的距离具有相同的数量级。由于XL-MIMO系统典型应用中UE密度的增加以及导频的稀缺，随机接入（RA）协议和调度算法的设计变得具有挑战性。在本文中，我们提出了一种联合RA和调度协议，即非重叠VR XL-MIMO（NOVR-XL）RA协议，该协议除了寻找非重叠的UE之外，还利用UE的不同VR来提高RA性能。 -在同一有效负载数据导频（PDP）资源中调度重叠的VR。我们的结果表明，与传统的 RA 方案相比，所提出的方案在总速率方面取得了显着的进步，并且总体上减少了访问延迟并提高了连接性能。