The Content Placement Problem in D2D Networks Under Coupling Distributed Caching and Distributed Storage.

In this paper, we address the distributed caching device-to-device (D2D) network in which the popular contents are cached proactively as chunks in the storage of users' devices (referred to as "helpers") in order to offload the content delivery traffic and reduce the transmission delay. If a content is cached as a chunk-based content, the requester has to download all the chunks of this content, thus, he may encounter a case wherein the consumed energy for obtaining this chunk-based content exceed the one for obtaining the same content as single-based content, if any. As the dissemination of a content as a single-based content can considerably impact the helper energy expenditure, the chunk-based caching may incurs additional energy burden owing to the limited battery capacity. So, in order to optimally trade-off between energy consumption and transmission delay, we propose a hybrid strategy wherein each content is cached simultaneously as single-based strategy and chunk-based strategy. We show through simulations that the proposed strategy outperforms these two strategies and achieves the trade-off.