Dynamic Resource Caching in the IoT Application Layer for Smart Cities

We propose to apply constrained application protocol publish/subscribe to cache popular Internet of Things (IoT) resources in a broker to reduce the energy consumption of servers (which host these popular resources) and the average delay for delivering the IoT resources' contents to the clients. We provide the smart parking application in smart cities as an example to demonstrate the benefit for conducting popular IoT resource caching. However, caching popular IoT resources in the broker may not always be the optimal choice, i.e., the broker may be congested by caching too many IoT resources, and so the average delay for enabling the broker to deliver contents of the IoT resources may be unbearable. Thus, we propose a novel energy aware and latency guaranteed dynamic resource caching (EASE) strategy to enable the broker to cache suitable popular resources such that the energy savings from the servers are maximized, while the average delay for publishing the contents of the resources to the corresponding clients is minimized. We demonstrate the performances of EASE via simulations as compared to other two baseline IoT resource caching strategies.