Primers: How Are Wireless Sensor Nodes Used?

Wireless Sensor Nodes are much more sophisticated than simple network termination units, commonly referred to as "tags."  Tags typically are capable of only communicating with a network that is made up of far more sophisticated components that monitor and route messages, and in many cases, change the message format that is received from the tags. All of these capabilities are included in a wireless sensor node. These functions, in addition to the control of the sensors themselves, are under the control of a local processor or computer that takes appropriate actions based upon the data or messages that it receives.

Typically, nodes participate in the control and flow of messages in the network to provide order and reduce congestion.  In some configurations, nodes contain static, pre-defined routing tables that result in messages always being routed to specific locations.  In other configurations, nodes may change the paths used to route messages. There are many different techniques and protocols that are used to determine the appropriate routing for a node and the network to use based upon many factors. The TeraHop network implementation uses an on-demand, ad hoc method of routing. This arrangement allows the network to be formed only when there is useful information to be passed. This approach dramatically increases the battery life of the nodes, reduces self-generated interference, accommodates widely varying coverage conditions, and accommodates a large concentration of devices.