5G Optimized Caching and Downlink Resource Sharing for Smart Cities

In smart cities, millions of things, systems, and people are interconnected and communicate with each other over wireless sensor networks, Internet of Things (IoT), and 5G networks. A tremendous amount of data traffic, which is frequently generated by the things in wireless multimedia sensor networks (WMSNs) and/or IoT, is accessed by a massive number of mobile users (MUs). These MUs are all competing to access the 5G network for data as well as urban applications and services. This can in turn cause exhaustion to the 5G network. In such cases, users can experience low data delivery and traffic congestions through backhaul links by macro base stations (MBSs). In this paper, we propose a joint caching and downlink resource sharing optimization framework (CSF) in 5G networks to assist WMSNs to efficiently deliver multimedia contents to the MUs. The CSF enables the MBSs to optimally decide how many replicas of each multimedia content to cache in which fem to base stations for high multimedia content hit rate. It also optimally exploits the MUs that are willing to share their downlink resources and that have retrieved multimedia contents, for offloading with device-to-device communications. The objective is to eventually maximize the system delivery capacity. Simulation results demonstrate that the CSF provides the best performance in terms of hit rate and system delivery capacity.