Channel state information (CSI) has been a key component in traditional wireless communication systems. This might no longer hold in future networks supporting services with stringent quality of service constraints such as extremely low latency, low energy, and/or large number of simultaneously connected devices, where acquiring CSI would become extremely costly or even impractical. We overview the main limitations of CSI at the transmitter side (CSIT)-based designs toward the 6G era, assess how to design and use efficient CSIT-limited schemes that allow meeting the new and stringent requirements, and highlight some key research directions. We delve into the ideas of efficiently allocating pilot sequences, relying on statistical CSIT and/or using location-based strategies, and demonstrate viability via a selected use case.

中文翻译：

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6G时代的超低时延、低能耗、海量，高效的CSIT-Limited方案

信道状态信息 (CSI) 一直是传统无线通信系统中的关键组件。这可能不再适用于支持具有严格服务质量约束（例如极低延迟、低能耗和/或大量同时连接的设备）的服务的网络，在这些网络中，获取 CSI 将变得极其昂贵甚至不切实际。我们概述了面向 6G 时代的基于发射机侧 (CSIT) 设计的 CSI 的主要限制，评估如何设计和使用满足新的严格要求的高效 CSIT 限制方案，并强调一些关键研究方向。我们深入研究了有效分配导频序列、依靠统计 CSIT 和/或使用基于位置的策略的想法，并通过选定的用例证明了可行性。