We consider a cache-aided wireless device-to-device (D2D) network of the type introduced by Ji, Caire, and Molisch [1], where the placement phase is orchestrated by a central server. We assume that the devices' caches are filled with uncoded data, and the whole content database is contained in the collection of caches. After the cache placement phase, the files requested by the users are serviced by inter-device multicast communication. For such a system setting, we provide the exact characterization of the optimal load-memory trade-off under the assumptions of uncoded placement and one-shot delivery. In particular, we derive both the minimum average (under uniformly distributed demands) and the minimum worst-case sum-load of the D2D transmissions, for given individual cache memory size at disposal of each user. Furthermore, we show that the performance of the proposed scheme is within factor $4$ of the information-theoretic optimum. Capitalizing on the one-shot delivery property, we also propose an extension of the presented scheme that provides robustness against random user inactivity.

翻译：我们考虑的是Ji、Caire和Molisch[1]采用的那种缓存辅助无线装置到装置(D2D)网络,其定位阶段是由中央服务器操纵的。我们假设,装置的缓存装满了未编码的数据,而整个内容数据库包含在缓存的收集中。在缓存放置阶段之后,用户所要求的文件由跨构件多播式通信提供服务。对于这样一个系统设置,我们提供未经编码的放置和一发投送假设下的最佳负载-模样交换的准确特征。特别是,我们提出了最低平均数(根据统一分布的要求)和D2D传输的最低最坏总和,因为每个用户都有个人缓存大小。此外,我们表明拟议办法的性能在信息理论最佳的因数4美元之内。我们利用了一发运财产,我们还提议扩大所提出的计划的范围,为避免随机用户的不活跃提供稳健。