The Smart Grid concept has been conceived as the integration of the electrical grid (generation, transmission and distribution) and the communications network of an electric utility. Although, traditional communications interfaces, protocols and standards has been used in the electrical grid in an isolated manner, modern communications networks are considered as the fundamental enabling technologies within a Smart Grid environment. Emerging communications technologies, protocol architectures and standards can help to build a common communications network infrastructure for data transport between customer premises, power substations, power distribution systems, utility control centers and utility data centers. The Smart Grid will support traditional applications such as supervisory control and data acquisition (SCADA), distribution automation (DA), energy management systems (EMS), demand site management (DSM) and automated meter reading (AMR), etc., as well as new applications like advanced metering infrastructure (AMI), substation automation (SA), microgrids, distributed generation (DG), grid monitoring and control, data storage and analysis, among others. To make this possible, the Smart Grid requires a two-way wide area communications network between different dispersed areas, from generation to consumer premises. An AMI system uses communication technologies for smart meter reading several times a day to get data consumption of electricity, as well as sending outage alarm information and meter tampering almost in real time, from the meter to the control center. Currently, there are various communication technologies to implement AMI systems. This paper presents an overview of the most relevant communications technologies that can be used to implement AMI communications infrastructure such as neighborhood area networks (NAN), field area networks (FAN) and wide area networks (WAN) using different transmission media such as fiber optics, spread spectrum radio frequency, microwave, WiMax, Wi-Fi, ZigBee, cellular, and power line carrier. In addition, a review of the current state of various AMI projects around the world, including the progress in the implementation of AMI systems in Mexico, besides the evaluation performance of CFE´s AMI networks
