We consider distributed and dynamic caching of coded content at small base stations (SBSs) in an area served by a macro base station (MBS). Specifically, content is encoded using a maximum distance separable code and cached according to a time-to-live (TTL) cache eviction policy, which allows coded packets to be removed from the caches at periodic times. Mobile users requesting a particular content download coded packets from SBSs within communication range. If additional packets are required to decode the file, these are downloaded from the MBS. We formulate an optimization problem that is efficiently solved numerically, providing TTL caching policies minimizing the overall network load. We demonstrate that distributed coded caching using TTL caching policies can offer significant reductions in terms of network load when request arrivals are bursty. We show how the distributed coded caching problem utilizing TTL caching policies can be analyzed as a specific single cache, convex optimization problem. Our problem encompasses static caching and the single cache as special cases. We prove that, interestingly, static caching is optimal under a Poisson request process, and that for a single cache the optimization problem has a surprisingly simple solution.

中文翻译：

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无线网络中的动态编码缓存

我们考虑在宏基站 (MBS) 服务的区域中的小型基站 (SBS) 上分布式和动态缓存编码内容。具体而言，内容使用最大距离可分离代码进行编码，并根据生存时间 (TTL) 缓存逐出策略进行缓存，该策略允许定期从缓存中删除编码数据包。请求特定内容的移动用户从通信范围内的 SBS 下载编码包。如果需要额外的数据包来解码文件，则从 MBS 下载这些数据包。我们制定了一个通过数值有效解决的优化问题，提供 TTL 缓存策略，最大限度地减少整体网络负载。我们证明，当请求到达突发时，使用 TTL 缓存策略的分布式编码缓存可以显着减少网络负载。我们展示了如何将利用 TTL 缓存策略的分布式编码缓存问题分析为特定的单个缓存、凸优化问题。我们的问题包括静态缓存和作为特殊情况的单一缓存。我们证明，有趣的是，静态缓存在 Poisson 请求过程下是最佳的，并且对于单个缓存，优化问题有一个非常简单的解决方案。