Wireless Sensor and Actuator Networks: Algorithms and Protocols for Scalable Coordination and Data Communication

4.1 FLOODING-BASED ROUTING AND GEOROUTING IN SENSOR NETWORKS

Sensors report their measurement to a monitoring station, also called a base station, or simply, a sink. Individual reporting of discovered events are normally done by a routing task, from a sensor to the sink. In a routing task, a packet is to be sent from a source node to a destination node, via some intermediate nodes in a given multihop network. In wireless sensor networks, the source is normally a sensor while the destination is a sink. In sensor-actuator networks, the actuator (actor) may serve as a source and/or destination node. Sinks, actuators, and even sensors could be fixed or mobile.

Existing practical implementations of sensor networks normally avoid the use of position information due to current technological difficulties in providing it to sensors with sufficient accuracy. Routing is then based on flooding as a step to find a route. Flooding was covered in Chapter 2. It will be reviewed again in Chapter 6 to illustrate data gathering and data aggregation by constructing a tree centered at the sink/actuator. Monitoring center floods route discovery (short) message to all sensors located inside a region. Sensors establish links toward the sensor from which the first copy of the packet is received, and use that link for reporting, or forwarding reports received from neighbors. Thus, effectively, sensors report along the reverse broadcast tree. In wireless ad hoc networks, this method is currently a candidate ...