constraineddevice

A constrained device refers to a computing device with restricted processing power, memory, storage, and energy availability. Such devices are typically small embedded systems that operate in environments where power is scarce, network bandwidth is limited, and physical access may be restricted. They are commonly used in Internet of Things deployments, smart sensors, and actuator nodes, where efficiency and long battery life are essential.

Key characteristics include limited CPU speed, small RAM and flash storage, and a need to minimize energy consumption. Many constrained devices run compact software stacks or lightweight operating systems, and may operate with intermittent connectivity or in lossy networks. To meet these constraints, software is optimized for small code size, predictable memory use, and simple, event-driven or cooperative multitasking models.

Communication with constrained devices relies on lightweight protocols and architectures. Prominent examples are the Constrained Application Protocol (CoAP) over UDP and, in some cases, MQTT-SN. These devices often connect through constrained networks such as 6LoWPAN, Bluetooth Low Energy, or Zigbee. Security solutions emphasize efficiency, using methods like DTLS with pre-shared keys or OSCORE for end-to-end protection with reduced overhead.

Standards and terminology are shaped by the IETF. RFC 7228 provides a definition for a constrained device, describing the resource limitations that influence software and networking capabilities. The concept is central to constrained node networks (CNET) and the broader field of IoT.

Typical applications include environmental sensing, smart buildings and cities, industrial automation, and asset tracking, where small, low-power devices collect data or perform simple control tasks.