08-03-2011, 12:13 PM
PRESENTED BY:
Vineet gupta
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ABSTRACT
My seminar topic is “ZigBee”. ZigBee is a new wireless technology developed by the ZigBee Alliance to overcome the limitations of BLUETOOTH and Wi-Fi. ZigBee is developed on the top of IEEE 802.15.4 standard. It is designed for low-power consumption allowing batteries to essentially last forever.Though we have couple of methods for multimedia applications, 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.IEEE 802.15.4 standard has two basic layers medium Access Control (MAC) and Physical Layer (PHY) wireless standard. The network layer supports various topologies such star, clustered tree topology and self healing mesh topology. Apart from easy installation and easy implementation ZigBee has a wide application area such as home networking, industrial networking, many more having different profiles specified for each field. The upcoming of ZigBee will revolutionize the home networking and rest of the wireless world.
Introduction:
ZigBee is an established set of specifications for wireless personal area networking (WPAN), i.e. digital radio connections between computers and related devices.
WPAN Low Rate or ZigBee provides specifications for devices that have low data rates, consume very low power and are thus characterized by long battery life. ZigBee makes possible completely networked homes where all devices are able to communicate and be controlled by a single unit.
ZigBee is a low-cost, low-power, wireless mesh networking standard. First, the low cost allows the technology to be widely deployed in wireless control and monitoring applications. Second, the low power-usage allows longer life with smaller batteries. Third, the mesh networking provides high reliability and more extensive range.
ZigBee is designed for wireless controls and sensors. It could be built into just about anything you have around your home or office, including lights,switches, doors and appliances. These devices can then interact without wires, and you can control them all . . . from a remote control or even your mobile phone.Although ZigBee's underlying radio-communication technology isn't revolutionary, it goes well beyond single-purpose wireless devices, such as garage door openers and "The Clapper" that turns light on and off. It allows wireless two-way communications between lights and switches, thermostats and furnaces, hotel-room air-conditioners and the front desk, and central command posts. It travels across greater distances and handles many sensors that can be linked to perform different tasks.
Zigbee Alliance
The ZigBee Alliance is an association of companies working together to enable reliable, cost-effective, and low-power wirelessly networked monitoring and control products based on an open global standard.
Origin of ZigBee name
The name of the brand is originated with reference to the behaviour of honey bees after their return to the beehive.
Zigbee characteristics
The focus of network applications under the IEEE 802.15.4 / ZigBee standard include the features of low power consumption, needed for only two major modes (Tx/Rx or Sleep), high density of nodes per network, low costs and simple implementation. These features are enabled by the following characteristics (technical data from ZigBee: 'Wireless Control That Simply Works') :
• 2.4GHz and 868/915 MHz dual PHY modes. This represents three license-free bands: 2.4-2.4835 GHz, 868-870 MHz and 902-928 MHz. The number of channels allotted to each frequency band is fixed at sixteen (numbered 11-26), one (numbered 0) and ten (numbered 1-10) respectively. The higher frequency band is applicable worldwide, and the lower band in the areas of North America, Europe, Australia and New Zealand .
• Low power consumption, with battery life ranging from months to years. Considering the number of devices with remotes in use at present, it is easy to see that more numbers of batteries need to be provisioned every so often, entailing regular (as well as timely), recurring expenditure. In the ZigBee standard, longer battery life is achievable by either of two means: continuous network connection and slow but sure battery drain, or intermittent connection and even slower battery drain.
• Maximum data rates allowed for each of these frequency bands are fixed as 250 kbps @2.4 GHz, 40 kbps @ 915 MHz, and 20 kbps @868 MHz. • High throughput and low latency for low duty-cycle applications (<0.1%) • Channel access using Carrier Sense Multiple Access with Collision Avoidance (CSMA - CA) • Addressing space of up to 64 bit IEEE address devices, 65,535 networks • 50m typical range • Fully reliable “hand-shaked” data transfer protocol. • Different topologies as illustrated below: star, peer-to-peer, mesh
• Band – 868, 902-928MHz, and 2.4GHz
• Topology – Ad-hoc, Star, Point to Point, Mesh
• Data Rate – 20/40Kb/s and 250Kb/s
• Power Consumption – Very Low
• Range – 10-100+ meters
• Security – very high; AES-128 level encryption
• Size – up to 64K nodes in a single logical network
Device Types
There are three different ZigBee device types .These devices have 64-bit IEEE addresses, with option to enable shorter addresses to reduce packet size, and work in either of two addressing modes – star and peer-to-peer.
1. The ZigBee(PAN) coordinator node :
There is one, and only one, ZigBee coordinator in each network to act as the router to other networks, and can be likened to the root of a (network) tree. It is designed to store information about the network.
2. The full function device FFD :
The FFD is an intermediary router transmitting data from other devices. It needs lesser memory than the ZigBee coordinator node, and entails lesser manufacturing costs. It can operate in all topologies and can act as a coordinator.
3. The reduced function device RFD :
This device is just capable of talking in the network; it cannot relay data from other devices. Requiring even less memory, (no flash, very little ROM and RAM), an RFD will thus be cheaper than an FFD. This device talks only to a network coordinator and can be implemented very simply in star topology.
