  Smart city vision brings emerging heterogeneous communication technologies
such as Fog Computing (FC) together to substantially reduce the latency and
energy consumption of Internet of Everything (IoE) devices running various
applications. The key feature that distinguishes the FC paradigm for smart
cities is that it spreads communication and computing resources over the
wired/wireless access network (e.g., proximate access points and base stations)
to provide resource augmentation (e.g., cyberforaging) for resource and
energy-limited wired/wireless (possibly mobile) things. Moreover, smart city
applications are developed with the goal of improving the management of urban
flows and allowing real-time responses to challenges that can arise in users'
transactional relationships. This article presents a Fog-supported smart city
network architecture called Fog Computing Architecture Network (FOCAN), a
multi-tier structure in which the applications running on things jointly
compute, route, and communicate with one another through the smart city
environment to decrease latency and improve energy provisioning and the
efficiency of services among things with different capabilities. An important
concern that arises with the introduction of FOCAN is the need to avoid
transferring data to/from distant things and instead to cover the nearest
region for an IoT application. We define three types of communications between
FOCAN devices (e.g., interprimary, primary, and secondary communication) to
manage applications in a way that meets the quality of service standards for
the IoE. One of the main advantages of FOCAN is that the devices can provide
the services with low energy usage and in an efficient manner. Simulation
results for a selected case study demonstrate the tremendous impact of the
FOCAN energy-efficient solution on the communication performance of various
types of things in smart cities.
