Category Archives: Smart Homes

This series focuses on which wireless home automation platform may make more sense for your requirement. In part 1, we tackle Zigbee.

ZIGBEE TECHNOLOGY: ZigBee is the original and open global wireless standard. This is appropriate in radio environment and remote areas. ZigBee technology formed on IEEE standard 802.15.4 which describes the operation of low rate WPAN. it covers up to 70mts(that is the distance between from station to another station). The main applications of this technology is sensors, lighting controls and many more applications. The ZigBee network layer supports both star and tree network topology, and very comprehensively mesh network. ZigBee operates at different frequency rates in the industries, scientific and medical radio bands: 2.4 GHz used most in worldwide and some devices in China, Europe and the USA also uses 784 MHz, 868 MHz and 915MHz respectively, however 2.4GHz frequency rate is still use in those regions and countries for commercial ZigBee devices. 20 kbit/s (868 MHz band) to 250 kbit/s (2.4 GHz band) is the data rate variation . ZigBee basically formed on the physical layer and media area control (MCA) which are defined by IEEE standard 802.15.4 for (WPANs). Specifies some additional key components, they are

ZODs: ZODs performs some tasks that includes keeping track of device roles, handles all the requests to join a network, device discovery and security.

NETWORK LAYER: The network layer are used to make the correct use of the MAC sublayer and to provide a sufficient interface for use by the application. It performs with network functions like connecting, disconnecting, and setting up networks. It will also perform operations like add a network, allocate addresses, and add/remove certain devices. This layer uses star, mesh and tree topologies.

APPLICATION LAYER: The highest-level layer is the application layer which provides the effective interface of the ZigBee system to its end users. It combines both ZDO and its management procedures, together with application objects defined by the manufacturer, are considered part of this layer. This layer binds tables, sends messages between bound devices, manages group addresses, reassembles packets and also transports data. It is responsible for providing service to ZigBee device profiles.

ZigBee networks are not limited to any specific number of  hops. A ZigBee network theoretically could have some 65K devices connected to it but it is possible to reach up 65K devices cause it would run into bandwidth problem.

ZIGBEE INTEROPERABILITY: ZigBee technology is an open and original global wireless standard that is maintained by the ZigBee Alliance. A group of companies that support its development and its use is called as a ZigBee Alliance. The biggest strike of this is lack of interoperability due to confusion with the certification program. There are actually two levels of certification. One certifies hardware and software. It is possible that a product may get their hardware certification but not their software. Products like this might be labelled “ZigBee-ready”. A consumer may buy the product expecting it to work with all the other ZigBee products but it won’t. actually there are many interoperable ZigBee devices but it has got a bad reputation because of the loose of certification process.