WSNs

Wireless sensor networks (WSNs) are networks of spatially distributed autonomous sensors that monitor physical or environmental conditions, such as temperature, sound, or pressure, and cooperatively pass their data through the network to a central location for processing and analysis. WSNs are designed to operate unattended for long periods on constrained power and computational resources.

Nodes in a WSN typically consist of a microcontroller, memory, a radio transceiver, sensors, and a power source, often a battery or energy-harvesting device. The network may be organized in flat, cluster-based, or hierarchical architectures. In many deployments, data is relayed to a base station or gateway via multi-hop paths, reducing energy expenditure on any single node.

Operating in a WSN involves sensing, local processing, data aggregation, and communication. Because energy is scarce, protocols emphasize low duty cycles and energy-efficient communication. MAC protocols (for example, IEEE 802.15.4 and light-weight schedules) and routing protocols (such as Directed Diffusion, LEACH variants, and PEGASIS) are common, often with data-centric or query-based approaches.

WSNs find applications in environmental monitoring, agriculture, smart cities, industrial automation, health monitoring, and disaster response. Major challenges include limited energy, unreliable wireless links, node failures, scalability, and security. Security concerns include eavesdropping, tampering, and node compromise, motivating the use of lightweight cryptography and secure routing.

Standardization efforts and technologies that support WSNs include IEEE 802.15.4, Zigbee, 6LoWPAN, and IP-based solutions. Research continues in energy harvesting, cross-layer optimization, data fusion, and edge computing to extend network lifetime and enhance reliability.