论文标题
三用户D2D编码的缓存，带有两个随机请求者和一个发件人
Three-user D2D Coded Caching with Two Random Requesters and One Sender
论文作者
论文摘要
在设备到设备（D2D）编码的缓存问题中，并非所有用户都可能在交货阶段提出文件请求。因此，我们提出了一个新的D2D集中式编码缓存问题，该问题名为3用户D2D编码的缓存，带有两个随机请求者和一个发件人（2RR1），在此，在交货阶段，三个用户中的任何两个都会提出文件请求，而没有提出任何文件请求的用户是指定的发件人。我们通过证明匹配的相反和可实现的结果，找到了任何数量的文件n，找到了最佳的缓存和交付方案，称为2RRIS方案。结果表明，需要进行编码的缓存位置以实现最佳性能。此外，最佳速率内存权衡对n> = 4具有均匀的表达，而n = 2和3的表达式不同。 为了检查提出的模型和方案的有用性，我们将2RR1S方案调整为三种情况。第一个是Ji等人提出的3用户D2D编码的缓存模型。通过表征3用户D2D编码的缓存的最佳速率内存权衡，当时n = 2（以前未知），我们表明，适应的2RR1S方案实际上对于3用户D2D编码的缓存问题是最佳的，当n = 2时，CACHE大小是中等的。好处来自编码的缓存位置，这是现有的D2D编码缓存方案所缺少的。第二种情况是在交付阶段，每个用户都以相同的概率p随机和独立地进行文件请求。我们将此模型称为请求随机D2D编码的缓存问题。将2RR1S方案调整到这种情况下，我们显示了适用于中等高速缓存大小的其他现有D2D编码的缓存方案的优越性。第三种情况是带有K-S随机请求者和S发件人问题的K-用户D2D编码的缓存，通过概括2RR1S方案，获得了可实现的结果。
In device-to-device (D2D) coded caching problems, it is possible that not all users will make file requests in the delivery phase. Hence, we propose a new D2D centralized coded caching problem, named the 3-user D2D coded caching with two random requesters and one sender (2RR1S), where in the delivery phase, any two of the three users will make file requests, and the user that does not make any file request is the designated sender. We find the optimal caching and delivery scheme, denoted as the 2RRIS scheme, for any number of files N by proving matching converse and achievability results. It is shown that coded cache placement is needed to achieve the optimal performance. Furthermore, the optimal rate-memory tradeoff has a uniform expression for N>=4 and different expressions for N=2 and 3. To examine the usefulness of the proposed model and scheme, we adapt the 2RR1S scheme to three scenarios. The first one is the 3-user D2D coded caching model proposed by Ji et al. By characterizing the optimal rate-memory tradeoff for the 3-user D2D coded caching when N=2, which was previously unknown, we show that the adapted 2RR1S scheme is in fact optimal for the 3-user D2D coded caching problem when N=2 and the cache size is medium. The benefit comes from coded cache placement which is missing from existing D2D coded caching schemes. The second scenario is where in the delivery phase, each user makes a file request randomly and independently with the same probability p. We call this model the request-random D2D coded caching problem. Adapting the 2RR1S scheme to this scenario, we show the superiority of our adapted scheme over other existing D2D coded caching schemes for medium to large cache size. The third scenario is the K-user D2D coded caching with K-s random requesters and s senders problem, for which an achievability result is obtained by generalizing the 2RR1S scheme.
