Overview#

As embedded system design has evolved and the Internet of Things (IoT) has emerged, the need for networking support has become a basic design requirement. Like more general-purpose computers, embedded systems have moved toward wireless networking. Most wireless networks have pushed toward ever-higher data rates and greater point-to-point ranges. But not all design applications require high-end wireless networking capabilities. Low-data-rate applications have the potential to outnumber the classic high-data-rate wireless networks worldwide. Simple applications such as lighting control, smart utility meters, Heating, Ventilation, and Air Conditioning (HVAC) control, fire/smoke/CO alarms, remote doorbells, humidity monitors, energy usage monitors, and countless other devices function very well with low-data-rate monitoring and control systems. The ability to install such devices without extensive wiring decreases installation and maintenance costs. Increased efficiencies and cost savings are the primary motives behind this applied technology.

A wireless sensor network (WSN) is a wireless network consisting of distributed devices using sensors at different locations to cooperatively monitor physical or environmental conditions, such as temperature, sound, vibration, pressure, motion, or pollutants.

In addition to one or more sensors, each node in a sensor network is typically equipped with a radio transceiver or other wireless communications device, a small microcontroller, and an energy source, usually a battery. The size of a single sensor node can vary from shoebox-sized nodes down to devices the size of coins. The cost of sensor nodes is similarly variable, depending on the size of the sensor network and the complexity required of individual sensor nodes. Size and cost constraints on sensor nodes result in corresponding constraints on resources such as energy, memory, computational speed, and bandwidth.

Wireless personal area networks have emerged partially as a result of the IEEE 802.15.4 standard for low data rate digital radio connections between embedded devices. Above the medium access control (MAC) and physical (PHY) layers, there have been a number of standards formed such as The Connectivity Standards Alliance and the Thread Group, which were formed to standardize industry efforts to supply technology for networking solutions that are based on 802.15.4, have low data rates, consume very little power, and are therefore characterized by long battery life. The Zigbee Standard makes possible complete and cost-effective networked homes and similar buildings where all devices are able to communicate for monitoring and control. The Thread Group brings IPv6 to these small embedded devices.