IEEE 802.15.4-2003 (Low Rate WPAN) is a radio communication standard for part of the complete wireless radio protocol (see Wireless Protocol). It specifically is targeted at applications with low data rate and low radio power consumption which can therefore be battery operated with very long battery life (months or even years) and very low complexity. The first edition of the 802.15.4 standard was released in May 2003.
Mesh networking is a way to route data and instructions between nodes. It allows for continuous connections and reconfiguration around broken or blocked paths by “hopping” from node to node until the destination is reached.
Individual elements in a wireless sensor network that perform the function of sensing some physical parameter (sensor node ), routing messages through the network (mesh or repeater node) or linking to an existing wired infrastructure (gateway or bridge node).
The ability of a mesh network, upon installation and activation, to automatically determine the optimal connections between nodes to create the mesh and to create the optimal routes through the mesh network from each sensing node via the mesh nodes to the gateway or bridge node. It also refers to the ability of an existing mesh network to discover a newly activated node and incorporate it into the network without the need for manual intervention. This feature can be restricted in some systems to prevent unauthorised devices from joining an established network.
The ability of a mesh network to route messages via alternative paths without the need for manual intervention in the event of one or more nodes failing.
Star networks rely on a central base-station that communicates directly to sensor nodes. The failure of an individual link means that information is lost.
ZigBee is the name of a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs).
Wireless Personal Area Network. Personal Area Networks are designed for ad-hoc short range communication, originally with about 10 metre range to allow wireless communication in the environs of a ‘person’. An example application would be connecting a mobile phone to a printer or laptop. Bluetooth is a good example of a WPAN protocol.
In radio data applications the way the data that is transferred over the radio link and gets from the device at one end to the device at the other end through the radio hardware and airwaves must be designed. That design is called a radio protocol. Radios such as IEEE 802.15.4 are digital. This introduces many of the concepts of wired digital data networks (such as Ethernet) into the design of radio networks. For ease of definition the radio protocol is divided into sections or ‘layers’ following the OSI seven layer model. For this reason it is often termed a ‘protocol stack’. The IEEE 802.15.4 standard only defines the lowest two layers of the stack (the Physical layer and the Medium Access Control (or MAC) layer). Many companies and alliances (such as ZigBee) have developed upper layers (Data Link, Network, Application Programming Interface layers) to complete the protocol. This means that, although protocols can be compliant with 802.15.4, as complete protocols they can all be very different. Bodies such as the ISA are now trying to define complete wireless mesh networking protocol stacks for industrial use.