Mobile networks are experiencing prodigious increase in data volume and user density , which exerts a great burden on mobile core networks and backhaul links. An efficient technique to lessen this problem is to use caching i.e. to bring the data closer to the users by making use of the caches of edge network nodes, such as fixed or mobile access points and even user devices. The performance of a caching depends on contents that are cached. In this paper, we examine the problem of content caching at the wireless edge(i.e. base stations) to minimize the discounted cost incurred over infinite horizon. We formulate this problem as a restless bandit problem, which is hard to solve. We begin by showing an optimal policy is of threshold type. Using these structural results, we prove the indexability of the problem, and use Whittle index policy to minimize the discounted cost.

翻译：移动网络正经历数据量与用户密度的激增，这对移动核心网络及回程链路造成了巨大负担。缓解该问题的有效技术之一是采用缓存，即利用边缘网络节点（如固定或移动接入点，甚至用户设备）的缓存功能，将数据更贴近用户。缓存的性能取决于被缓存的内容。本文研究了无线边缘（即基站）的内容缓存问题，旨在最小化无限时域上的折现成本。我们将该问题建模为难以求解的Restless Bandit问题。首先证明最优策略具有阈值类型结构。基于这些结构性结果，我们验证了问题的可索引性，并采用Whittle索引策略最小化折现成本。