Collaborative Caching for Energy Optimization in Content-Centric Internet of Things

The development of the content-centric Internet of Things (C2IoT) enriches the services provided by the IoT devices, which diversifies the provided contents. However, system resources are terribly wasted by repeated delivering the same content. Efficiently utilizing caching resources can reduce the link load caused by delivering and forwarding contents, further improving the users’ quality of experience (QoE). However, the collaboration among independent decision nodes is insufficient, which consumes substantial energy redundantly. To solve the mentioned issue, we propose a genetic-algorithm-based collaborative caching scheme integrating on-path strategy and off-path strategy, named cost-oriented caching scheme (CCS), to minimize the energy consumption of requesting contents. First, based on the analysis of content popularity, users’ historical requests, and transmission delay, an optimization problem is formulated to minimize the communication delay of obtaining content. Then, we formulate a submodular function optimization problem to optimize energy consumption, and an improved genetic algorithm is proposed to solve the mentioned problem. Performance evaluations demonstrate that the proposed CCS is superior to other existing caching schemes.

I. Introduction

The evolution and update of network technology have promoted the popularity of various mobile devices and the Internet-of-Things (IoT) terminals [1]. According to the global mobile data traffic forecast report released by Cisco [2], the total amount of mobile data of IoT generated globally will reach 396EB by 2022. As the data dramatically increases yearly [3], many problems, such as network delay and energy consumption, have already overwhelmed the traditional host-centric network. The network architecture has transformed from host-centric end-to-end communication to receiver-driven content retrieval. Thus, the content-centric Internet of Things (C2IoT) came into being. Efficient utilization of caching resources can reduce the network traffic, server workload, and user access delay and further improve the users’ quality of experience (QoE) [4], [5]. Therefore, caching resources are regarded as one of the most valuable resources to investigate in the IoT, which can directly affect the states and performance of the network. IoT is also regarded as the rather promising solution for managing resources [6]. Herein, caching-enhanced C2IoT is a promising direction since the caching resource utilization alleviates the network burden dramatically. The caching-enhanced C2IoT is illustrated in Fig. 1; each device has a certain storage capacity to cache contents and deliver them to requesters [7]. Information perception technique can recognize the cached content without applications [8], just like web caching. Caching contents intends to copy them regardless of which transmitting path is selected in the IoT [9]. The numbers of copies and the selection of copy nodes are determined according to the observed states of network and traffic. The caching decisions can be affected by many factors including node availability, available caching resources, and content popularity [10]. Those factors are made a tradeoff to construct a complex caching system, which is sensitive to short-term changes dramatically influencing mechanism complexity. Fig. 1.

Caching-enhanced C2IoT.