Glossary of Wireless Sensor Networks Terminology

BACnet

BACnet was designed to allow communication of building automation and control systems for applications such as heating, ventilating, and air-conditioning control, lighting control, access control, and fire detection systems and their associated equipment. The BACnet protocol provides mechanisms for computerized building automation devices to exchange information, regardless of the particular building service they perform.

DHCP service

Dynamic Host Configuration Protocol (DHCP) is a network protocol that enables a server to automatically assign an IP address to a computer from a defined range of numbers (i.e., a scope) configured for a given network.

Distributed frequency spread spectrum (DFSS)

Distributed Frequency Spread Spectrum, (DFSS) combines the properties of FHSS and DSSS. Like DSSS, DFSS uses a spread channel approach to transmit data. The spreading is intrinsic to 802.15.4 radios, where the data is spread across a channel about 3 megahertz wide. DFSS extends DSSS by dynamically changing the channel of all of the nodes in the network in a manner similar to frequency hopping.

Frequency-hopping technology

Various spread spectrum techniques that transmit data across a range of frequency channels (while remaining within a given radio “band”), have been designed to reduce a device’s susceptibility to interference. Frequency Hopping Spread Spectrum (FHSS) takes a data signal and transmits on a narrow-band frequency while rapidly changing or “hopping” across a group of frequency channels on a pre-defined but usually arbitrary pattern. Direct Sequence Spread Spectrum (DSSS) simultaneously transmits portions of the data across an entire range of frequencies within a channel of known width

Full function device (FFD)

A FFD or Full Function Device can operate as both an I/O device and a network router /repeater and is a key device in a Mesh Network architecture. Usually line powered as they have to stay on all the time

Gateway (PAN coordinator)

A Private Area Network (PAN) Coordinator which discovers and continuously manages the network devices (nodes)

GSM

GSM (Global System for Mobile Communications, originally Groupe Spécial Mobile), is a standard developed by the European Telecommunications Standards Institute (ETSI) to describe protocols for second generation (2G) digital cellular networks used by mobile phones

IEEE 802.15.4

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.

ISM Band

The industrial, scientific and medical (ISM) radio bands are radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than telecommunications.

LonWorks

LonWorks (local operating network) is a networking platform specifically created to address the needs of control applications. The platform is built on a protocol created by Echelon Corporation for networking devices over media such as twisted pair, powerlines, fiber optics, and RF.

MAC Address

A media access control address (MAC address) is a unique identifier assigned to network interfaces for communications on the physical network segment. MAC addresses are most often assigned by the manufacturer of a network interface controller (NIC) and are stored in its hardware, such as the card’s read-only memory or some other firmware mechanism.

Modbus TCP

Modbus is an application protocol, as it defines rules for organizing and interpreting data, but remains simply a messaging structure, independent of the underlying physical layer.
Modbus TCP (also Modbus-TCP/IP) is simply the Modbus RTU protocol with a TCP interface that runs on Ethernet.

Modbus RTU

Modbus RTU is an open, serial (RS-232 or RS-485) protocol derived from the Master/Slave architecture. It is a widely accepted protocol due to its ease of use and reliability. Modbus RTU is widely used within Building Management Systems (BMS)

Network topology

Network topology is the arrangement of the various elements (links, nodes, etc.) of a computer network. Essentially, it is the topological structure of a network, and may be depicted physically or logically. Physical topology refers to the placement of the network’s various components, including device location and cable installation, while logical topology shows how data flows within a network, regardless of its physical design. Distances between nodes, physical interconnections, transmission rates, and/or signal types may differ between two networks, yet their topologies may be identical.

Node

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).

PAN ID

The Co-ordinator starts the network, assigning a PAN ID (Personal Area Network identifier) to the network. The PAN ID can be pre-determined, or can be obtained dynamically by detecting other networks operating in the same frequency channel and choosing a PAN ID that does not conflict with theirs.

Reduced function device (RFD)

A RFD or Reduced Function Device only handles I/O and does not route signals from other devices. It is therefore dependent upon the FFD’s to broadcast and receive communications over the Mesh Network. Most often battery-powered and uses sleep-mode to conserve power. Sleep-mode operation is a key feature designed into the 802.15.4 standard

Self healing 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.

Self-forming network

Wireless sensor networks 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.

SNMP

Simple Network Management Protocol (SNMP) is an “Internet-standard protocol for managing devices on IP networks”. Devices that typically support SNMP include routers, switches, servers, workstations, printers, modem racks and more.SNMP is used mostly in network management systems to monitor network-attached devices for conditions that warrant administrative attention

Star Network

Wireless sensor networks employing a star network rely on a central base-station that communicates directly to sensor nodes. The failure of an individual link means that information is lost.

Static IP Address

Static IP addresses are manually assigned to a computer by an administrator.

Wireless sensor networks

Wireless sensor networks (WSN) refers to a group of spatially dispersed and dedicated sensors for monitoring and recording the physical conditions of the environment and organizing the collected data at a central location. Wireless sensor networks measure environmental conditions like temperature, sound, pollution levels, humidity, wind speed and direction, pressure, etc.

Wireless 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.

WPAN

Wireless Personal Area Networks (or wireless sensor 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.

Zigbee

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 sensor networks.