ZigBee is an open technology developed by the SigBee Alliance to overcome the limitations of
BLUETOOTH and Wi-Fi. ZigBee is an IEEE 802.15.4 standard for data communications with
business and consumer devices. It is designed around low-power consumption allowing batteries to
essentially last forever. BLUETOOTH as we know was developed to replace wires and Wi-Fi to
achieve higher data transfer rate, as such till now nothing has been developed for sensor networking
and control machines which require longer battery life and continuous working without human
intervention. ZigBee devices allow batteries to last up to years using primary cells (low cost)
without any chargers (low cost and easy installation).
The ZigBee standard provides network, security, and application support services operating on top
of the IEEE 802.15.4 Medium Access Control (MAC) and Physical Layer (PHY) wireless standard.
It employs a suite of technologies to enable scalable, self-organizing, self-healing networks that can
manage various data traffic patterns. The network layer supports various topologies such star, clustered tree topology and self healing mesh topology which is essential in Smartdust
Apart from easy installation and easy implementation ZigBee has a wide application area such as
home networking, industrial networking, Smartdust, many more, having different profiles specified
for each field. The upcoming of ZigBee will revolutionize the home networking and rest of the
It was in 1896 that Guglielmo Marconi invented the first wireless telegraph. In 1901 he sent
telegraphic signals across the Atlantic ocean from Cornwall to St. John’s Newfoundland; a distance
of 1800 miles. Over the last century, advances in wireless technologies have led to the radio, the television, the mobile telephone, and communication satellites. All type of information can now be
send to any corner of the world. A wireless network is a flexible data communication system, which uses wireless media such as radio frequency technology to transmit and receive data over the air, minimizing the need for wired connections. Wireless networks are used to augment rather than replace wired networks and are most commonly used to provide last few stages of connectivity between a mobile user and a wired network.
Wireless networks use electromagnetic waves to communicate information from one point to
another without relying on any physical connection. Radio waves are often referred to as radio carriers because they simply perform the function of delivering energy to a remote receiver. The data being transmitted is superimposed on the radio carrier so that it can be accurately extracted at the receiving end. Once data is superimposed (modulated) onto the radio carrier, the radio signal occupies more than a single frequency, since the frequency or bit rate of the modulating information adds to the carrier. Multiple radio carriers can exist in the same space at the same time without interfering with each other if the radio waves are transmitted on different radio frequencies. To extract data, a radio receiver tunes in one radio frequency while rejecting all other frequencies. The modulated signal thus received is then demodulated and the data is extracted from the signal. Wireless networks offer the following productivity, convenience, and cost advantages over traditional wired networks:
There is a plethora of standards under the IEEE 802 LMSC (LAN / MAN Standard Committee). Of
these even 802.11 has variety of standards, each with a letter suffix. These cover everything from
the wireless standards themselves, to standards for security aspects, quality of service and the like:
802.11a – Wireless network bearer operating in the 5 GHz. ISM band with data rate up to 54 Mbps.
802.11b – Wireless network bearer operating in the 2.4 GHz ISM band with data rates up to 11
802.11e – Quality of service and prioritization
802.11f – Handover
802.11g – Wireless network bearer operating in 24.GHz ISM band with data rates up to 54 Mbps
802.11h – Power control
802.11i – Authentication and encryption
802.11j – Internetworking
802.11k – Measurement reporting
802.11n – stream multiplexing
802.11s – Mesh networking
Of these the standards that are most widely known are the network bearer standards, 802.11a,
There are two types of network that can be formed: infrastructure networks; and ad-hoc networks.
The infrastructure application is aimed at office areas or to provide a “hotspot”. It can be installed
instead of a wired system, and can provide considerable cost savings, especially when used in
established offices. A backbone wired network is still required and is connected to a server.
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