This article proposes the concept of channel knowledge map (CKM) as an enabler toward environment-aware wireless communications. CKM is a site-specific database, tagged with the locations of the transmitters and/or receivers, that contains channel-related information useful to enhance environment-awareness and facilitate or even obviate sophisticated real-time channel state information (CSI) acquisition. Therefore, CKM is expected to play an important role for 6G networks targeting for super high capacity, extremely low latency, and ultra-massive connectivity, by offering potential solutions to practical challenges brought by the drastically increased channel dimensions and training overhead. In this article, the motivations of environment-awareness enabled by CKM are first discussed, followed by the key techniques to build and utilize CKM. In particular, it is highlighted that CKM is especially appealing for four channel types: channels for yet-to-reach locations, channels for non-cooperative nodes, channels with large dimensions, and channels with severe hardware/processing limitations. Two case studies with extensive numerical results are presented to demonstrate the great potential of environment-aware communications enabled by CKM.

中文翻译：

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通过信道知识图实现环境感知 6G 通信

本文提出了信道知识图 (CKM) 的概念，作为实现环境感知无线通信的推动因素。CKM 是一个特定于站点的数据库，标有发射器和/或接收器的位置，其中包含有助于增强环境意识和促进甚至避免复杂的实时信道状态信息 (CSI) 获取的信道相关信息。因此，CKM 有望为以超高容量、极低延迟和超大规模连接为目标的 6G 网络发挥重要作用，为信道维度和训练开销急剧增加所带来的实际挑战提供潜在的解决方案。在本文中，首先讨论了 CKM 实现环境感知的动机，然后是构建和利用 CKM 的关键技术。特别要强调的是，CKM 对四种通道类型特别有吸引力：用于尚未到达位置的通道、用于非合作节点的通道、大尺寸通道以及具有严重硬件/处理限制的通道。提供了两个具有广泛数值结果的案例研究，以证明 CKM 实现的环境感知通信的巨大潜力。