Medium Access Control Protocols for Wireless Sensor Networks

Recent improvements in affordable and effecient integrated electronic devices have a considerable impact on advancing the state of wireless sensor networks (WSNs), which constitute the platform of a broad range of applications related to national security, surveillance, military, health care, environmental monitoring, smart spaces, inventory tracking, and recently industrial controls. A WSN is a collection of a large number of wireless nodes deployed to measure and report certain parameters such as temperature, pressure, humidity, etc. Each node consists of sensing, processing, power and radio units. Sensor nodes are usually deployed to serve one application and are configured to operate as a multi-hop network. A WSN contains one or more sinks that relay data between users and sensor nodes. The main functions of a sensor node are to sense the surrounding environment and to participate in data forwarding. Additionally, a sensor node might perform data aggregation in order to reduce the bandwidth consumption, power consumption for communication, and media access delay. The two important operations of a WSN are data dissemination (send data/queries from sinks to sensor nodes) and data gathering (send sensed data from sensor nodes to the sinks).