Presented by:
P.V.S.Krishna
P.Nataraju

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ABSTRACT:
ZigBee is a low-cost, low-power, wireless mesh networking standard. The low cost allows the technology to be widely deployed in wireless control and monitoring applications, the low power-usage allows longer life with smaller batteries, and the mesh networking provides high reliability and larger range.
While Bluetooth focuses on connectivity between large packet user devices, such as laptops, phones, and major peripherals, ZigBee is designed to provide highly efficient connectivity between small packet devices. As a result of its simplified operations, which are one to two full orders of magnitude less complex than a comparable Bluetooth device, pricing for ZigBee devices is extremely competitive, with full nodes available for a fraction of the cost of a Bluetooth node.
What is ZigBee?
The name "ZigBee" is derived from the erratic zigging patterns many bees make between flowers when collecting pollen. This is evocative of the invisible webs of connections existing in a fully wireless environment. The standard itself is regulated by a group known as the ZigBee Alliance, with over 150 members worldwide.
INTRODUCTION:
ZigBee devices are actively limited to a through-rate of 250Kbps,compared to Bluetooth's much larger pipeline of 1Mbps, operating on the 2.4 GHz ISM band, which is available throughout most of the world.
ZigBee has been developed to meet the growing demand for capable wireless networking between numerous low-power devices. In industry ZigBee is being used for next generation automated manufacturing, with small transmitters in every device on the floor, allowing for communication between devices to a central computer. This new level of communication permits finely-tuned remote monitoring and manipulation. In the consumer market ZigBee is being explored for everything from linking low-power household devices such as smoke alarms to a central housing control unit, to centralized light controls.
The specified maximum range of operation for ZigBee
devices is 250 feet (76m), substantially further than that used by Bluetooth capable devices, although security concerns raised over "sniping" Bluetooth devices remotely,
may prove to hold true for ZigBee devices as well.
ZIGBEE:A FUTURE REVOLUTION:
Due to its low power output, ZigBee devices can sustain themselves on a small battery for many months, or even years, making them ideal for install-and-forget purposes, such as most small household systems. Predictions of
ZigBee installation for the future, most based on the explosive use of
ZigBee in automated household tasks in China, look to a near future when upwards of sixty
ZigBee devices may be found in an average American home, all
communicating with one another freely and regulating common tasks seamlessly.
Who Needs ZigBee?
We’re beginning to hear more and more about this wireless technology called ZigBee. A catchy name for sure, but what is it and who needs it? We already have Bluetooth- and Wi-Fi-enabled devices, and WiMAX and Wireless USB proliferation are at the doorstep. Who needs another wireless standard?
First, let’s understand that each wireless technology that makes it to market serves a special purpose or function. Bluetooth and wireless USB provide short-range connectivity in what is called a personal-area network (PAN). Bluetooth serves a short-range, moderate-speed, wire replacer, and wireless USB provides short-range, high-speed device connectivity. Wi-Fi is for local-area networks (LANs) and WiMAX is designed to provide wide-area networking (WAN) or metropolitan-area networking (MAN).
ZigBee fills yet another nitch. It is a PAN technology based on the IEEE 802.15.4 standard. Unlike Bluetooth or wireless USB devices, ZigBee devices have the ability to form a mesh network between nodes. Meshing is a type of daisy chaining from one device to another. This technique allows the short range of an individual node to be expanded and multiplied, covering a much larger area.
One ZigBee network can contain more than 65,000 nodes (active devices). The network they form in cooperation with each other may take the shape of a star, a branching tree or a net (mesh). What’s more, each device can operate for years off of a AA cell. That means that each node uses little power.
What might be perceived as a disadvantage is the low data rate of ZigBee devices, typically less than 100 kbps, depending on the selected frequency band. Is slow bad? That depends on the function or service the technology is intended to provide. That brings us to the opening question: Who needs ZigBee?
If you are looking for wireless monitoring and remote control solutions, ZigBee may be the answer.
Those are the functions for which ZigBee was designed. ZigBee nodes can be used to tie an entire home, office or factory together for safety, security and control.
Nodes are embedded in hundreds of sensors and controls that are built into large infrastructures for home automation, industrial automation, remote metering, automotives, medical equipment, patient monitoring, asset tracking systems, security systems, lighting and temperature control systems, and even toys.
There are three categories of ZigBee devices:
ZigBee Network Coordinator. Smart node that automatically initiates the formation of the network.
ZigBee Router. Another smart node that links groups together and provides multi-hoping for messages. It associates with other routers and end-devices.
ZigBee End Devices. Where the rubber hits the road—sensors, actuators, monitors, switches, dimmers and other controllers.
ZigBee networks provide smart, low-cost, low-power, low-maintenance monitoring and control systems.