Smart grid combines a set of functionalities that can only be achieved through ubiquitous sensing and communication across the electrical grid. The communication infrastructure must be able to cope with an increasing number of traffic types which is as a result of increased control and monitoring, penetration of renewable energy sources and adoption of electric vehicles. The communication infrastructure must serve as a substrate that supports different traffic requirements such as QoS (i.e. latency, bandwidth and delay) across an integrated communication system. This engenders the implementation of middleware systems which considers QoS requirements for different types of traffic in order to allow prompt delivery of these traffic in a smart grid system. A heterogeneous communication applied through the adaptation of the Ubiquitous Sensor Network (USN) layered structure to smart grid has been proposed by the International Telecommunication Union (ITU). This paper explores the ITU's USN architecture and presents the communication technologies which can be deployed within the USN schematic layers for a secure and resilient communication together with a study of their pro's and con's, vulnerabilities and challenges. It also discusses the factors that can affect the selection of communication technologies and suggests possible communications technologies at different USN layers. Furthermore, the paper highlights the USN middleware system as an important mechanism to tackle scalability and interoperability problems as well as shield the communication complexities and heterogeneity of smart grid. 
Resilient communication for smart grid ubiquitous sensor network: State of the art and prospects for next generation