Caching at the wireless edge nodes is a promising way to boost the spatial and spectral efficiency, for the sake of alleviating networks from content-related traffic. Coded caching originally introduced by Maddah-Ali and Niesen significantly speeds up communication efficiency by transmitting multicast messages simultaneously useful to multiple users. Most prior works on coded caching are based on the assumption that each user may request all content in the library. However, in many applications the users are interested only in a limited set of content items that depends on their location. For example, visitors in a museum may stream audio and video related to the artworks in the room they are visiting, or assisted self-driving vehicles may access super-high definition maps of the area through which they are travelling. Motivated by these considerations, this paper formulates the coded caching problem for location-based content with edge cache nodes. The considered problem includes a content server with access to N location-based files, K edge cache nodes located at different regions, and K users each of which is in the serving region of one cache node and can retrieve the cached content of this cache node with negligible cost. Depending on the location, each user only requests a file from a location-dependent subset of the library. The objective is to minimize the worst-case load transmitted from the content server among all possible demands. We propose a highly non-trivial converse bound under uncoded cache placement, which shows that a simple achievable scheme is optimal. In addition, this achievable scheme is generally order optimal within 3. Finally, we extend the coded caching problem for location-based content to the multiaccess coded caching topology, where each user is connected to L nearest cache nodes. When $L \geq 2$ we characterize the exact optimality on the worst-case load.

中文翻译：

---

基于位置内容的编码缓存的最佳负载记忆权衡

为了减轻网络与内容相关的流量，在无线边缘节点缓存是一种提高空间和频谱效率的有前途的方法。最初由 Maddah-Ali 和 Niesen 引入的编码缓存通过同时传输对多个用户有用的多播消息来显着提高通信效率。大多数关于编码缓存的先前工作都基于这样的假设：每个用户都可以请求库中的所有内容。然而，在许多应用程序中，用户只对有限的一组内容项目感兴趣，这取决于他们的位置。例如，博物馆的参观者可以流式传输与他们正在参观的房间内的艺术品相关的音频和视频，或者辅助自动驾驶汽车可以访问他们正在旅行的区域的超高清地图。基于这些考虑，本文制定了具有边缘缓存节点的基于位置的内容的编码缓存问题。考虑的问题包括可以访问 N 个基于位置的文件的内容服务器，位于不同区域的 K 个边缘缓存节点，以及 K 个用户，每个用户都在一个缓存节点的服务区域中，并且可以检索该缓存节点的缓存内容以微不足道的成本。根据位置的不同，每个用户仅从依赖于位置的库子集中请求一个文件。目标是在所有可能的需求中最小化从内容服务器传输的最坏情况负载。我们在未编码的缓存放置下提出了一个非常重要的逆界，这表明一个简单的可实现方案是最佳的。另外，这个可实现的方案一般是3阶以内的最优。最后，我们将基于位置的内容的编码缓存问题扩展到多访问编码缓存拓扑，其中每个用户都连接到 L 个最近的缓存节点。当 $L \geq 2$ 时，我们表征了最坏情况负载的精确最优性。