ABSTRACT
Next-generation cellular networks need to be designed to explore the benefits of device-to-device (D2D) communications with reference to the social and industrial Internet of Things (IoT). As the requirements of high-speed data communications are increasing at a rapid speed, current technologies are focusing on short-range communications for better energy and spectral efficiency. This chapter investigates various aspects of single and multi-hop D2D communications for social IoT (SIoT). In SIoT, D2D users follow several rules governed by their social relationship so that every user not only thinks of its benefit, but also thinks of overall social improvement. We focus on elaborating existing techniques for improving the energy and spectral efficiency, latency, and fairness of the D2D users. Employing multidimensional network status attributes such as local centrality, cooperation among users, content similarity, and other social parameters, intra-community and inter-community D2D communication mechanisms are devised for network optimizations. Thereafter, we discuss the state-of-the-art survey on incorporating D2D functionalities on top of SIoT architecture (modules, relational features, trust management, cooperation, and connectivity among different blocks). We further identify appropriate protocols for the integration of D2D SIoT architecture with upcoming 5G and beyond cellular networks. Various caching techniques are discussed that can improve the cache hit ratio in D2D-enabled SIoT networks. At the end, an in-depth investigation is done for improving the current technologies, and finally, future research directions are highlighted.
