Device-to-device content caching techniques in 5G: A taxonomy, solutions, and challenges

Over the past many years, content caching is one of the major challenges in the 5G environment. With the advent of the Internet of Things (IoT) and 5G, users want to access various services within a fraction of seconds resulting an extra burden on the underlying network infrastructure to maintain Quality of Service (QoS) and Quality of Experience (QoE) provisions of different applications for the end-users and service providers. However, caching the most popular contents followed by device-to-device (D2D) sharing can resolve the aforementioned problems. But, access delay is still one of the challenges in front of the research community during content caching using D2D communications in a 5G environment. Motivated from these facts, this paper provides an in-depth survey of various D2D based content caching techniques used for popular content sharing among different devices in the 5G environment. A detailed taxonomy is presented to give deep insights to the readers about the findings, constraints, and challenges of various existing proposals. Finally, a relative comparison of the existing D2D content caching proposals is given in the text with respect to various parameters. It gives deep insights to the readers about the applicability of different caching techniques in 5G.