14-02-2011, 03:03 PM
A.HEMANTH KUMAR
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Abstract
Zigbee is the new generation technology ,is the application in the Bluetooth technology. In this paper we discuss about the evolution of the technology ,existence of the technology ,compatibility with other technologies namely Bluetooth, Wi-Fi, GPRS and the areas of applications of the Zigbee technology. To overcome the disadvantages of recent wireless communications technologies which are spreading into many new areas, we are using the Zigbee technology. The existing technology has a wide applications in the areas home automation, data acquisition, building control, monitoring systems and industrial automation. The compatibility of this technology with other technologies namely Bluetooth, Wi-Fi, GPRS are discussed in the application areas.Zigbee technology is based on an industry standard, it provides interoperability, allowing communication amongst devices from different manufacturers, and offers system integrators and consumers flexible purchasing options. Zigbee technology also offers simplicity and a cost effective approach to building construction and remodeling with wireless technology
INTRODUCTION
Zigbee is a consortium of software, hardware and services companies that have developed a common standard for wireless networking of sensors and controllers. While other wireless standards are concerned with exchanging large amount of data, Zigbee is for devices that have smaller through put needs. The other driving factors are low cost, high reliability, high security, low battery usage, simplicity and interoperability with other Zigbee devices. ZigBee is a published specification set of high level communication protocols designed to use small, low-power digital radios based on the IEEE 802.15.4 standard for wireless personal area networks (WPANs). The relationship between IEEE 802.15.4 and ZigBee is analogous to that existing between IEEE 802.11 and the Wi-FiAlliance.‘ZigBee’ is a low rate, low power wireless Personal Area Protocol (LR-PAN) intended for low cost devices in automation, home controls and computer peripherals, Complex wiring in buildings and industries containing mesh of thousands of sensors can be done away with Zigbee technology.Zigbee is a low rate wireless personal area network (LR- WPAN) standard. Wireless personal area networks (WPANs) are used to convey information over relatively short distances. Unlike wireless local area networks, connections effected via WPANs involve little or no infrastructure. This feature allows small, power efficient, inexpensive solutions to be implemented for a wide range of devices.The ever decreasing cost and increase in performance of silicon radio frequency integrated circuits makes it practical to manufacture wireless communication capabilities into every day goods.Now with the introduction of the Zigbee wireless networking standard embedded system designers are integrating complete wireless systems on a chips on semiconductors smaller than a postal stamp, enabling product manufacturers to embedded very low cost, low power sensor and control capabilities to every day devices. At its most basic level, Zigbee simply ensures interoperability with other standard compliant products.Zigbee compliant embedded networks have several characteristics that set them apart from conventional wireless local area networks, such as IEEE 802.11.
A node in a Zigbee network has following features
Low powerRelatively low data ratesLow costsReliable, autonomous operationSecuritySelf-healing
Low power
Many applications must run unattended for years using battery power. Commercially available ZigBee system nodes consume less than 50mW when active and less than a microwatt in sleep mode. With a battery source of three Watt-hours, such systems will last 2.5days if active 100% of the time, but with a duty cycle of 0.1%, the same system will last over 6 years without a battery change. Battery life of a device is an important consideration in the design of the Zigbee standard. Many devices will have simple inexpensive batteries and will remain off most of the time. A device can be “pinged” to awaken or scheduled for a prearranged time. In this way the device is checked to see that it remains on the network, yet maximize battery life up to several years. The “sleep” mode and the very low duty cycle of active nodes typically as low as 0.1%, will ensure extensive battery life.
Relatively low data rates
Your average light switch communicates approximately four bits per day, or 46 microbaud. In many applications, high data rates are not a requirement. The Zigbee v1.0 specification defines a communication rate of 250 kilobits per second, which is more than adequate for low-rate sensing and control applications
LOW COSTS
Zigbee networks are engineered to be built into a broad spectrum of products, many of which are cost sensitive. It is now possible to purchase zigbee complaint systems an a chip for under $5.00, making them suitable for many commercial and consumer applications naturally, Moores law holds for RFICs as well as for other silicon devices, so the price of zigbee semiconductors will continue to fall over time and enable ever broader applications .
RELAIBLE, AUTONOMOUS OPERATION
Since there are typically many more nodes in a zigbee network than there are human attendants, nodes must be easy to deploy, operate reliably without human intervention and be self maintaining. A failure of a single node should not interrupt the operation of the entire network.
SECURITY
ZigBee uses 128 bit AES encryption algorithms for a highly secure network. In commercial or industrial settings, hackers might try to perform a denial of lighting, similar to a denial of service on internet sites that they hack into. This might not be done only to be disruptive, but on large buildings in major cities, hackers might be tempted to black out only some lights in order to spell words or slogans with the remaining lights. Access control through wireless connections might lead to break-ins and burglary in an insecure environment. For these reasons Zigbee has been designed to have a high level of security.
SELF-HEALING
While Zigbee can use a star topology or cluster tree topology the most useful is a mesh topology. In a mesh topology, any node can also serve as a router for other devices on the network. If there are barriers such as concrete or steel walls that interfere with the transmission of the radio frequency, another path is chosen to reach the desired device. Higher densities of devices in an area lead to stronger, more reliable networks. If one device should fail, the path is automatically rerouted through other nodes on the network. In this way the networks become “self-healing”.Zigbee can be used in commercial applications such as building maintenance for monitoring and controlling lights, Heating, ventilation and Air Conditioning (HVAC)Smoke alarms, fire alarms, burglar alarms, landscaping sprinklers and lights and many other uses. In health care, Zigbee can be used for patient monitoring equipment, fitness monitoring and other uses. Industrial environments can use Zigbee for asset monitoring, process control, assuring compliance with environmental standards and energy management used correctly, zigbee enabled devices can give a warning before a breakdown occurs so that repairs can be made in the most effective manner. They can also be used to maintain quality and reduce waste.In a home security system, for example, wireless sensors would be much easier to install than sensors that need wiring. The same is true in industrial environments, where wiring typically accounts for 80% of the cost of sensor installations .and then there are applications for sensors where wiring is not practical or even possible
ZIGBEE APPLICATIONS
Zigbee technology is well suited to a wide range of building automation, industrial, medical and residential control & monitoring applications. Essentially, applications that require interoperability and/or the RF performance characteristics of the IEEE 802.15.4 standard would benefit from a ZigBee solution.
Examples include
Lighting ControlsAutomatic Meter ReadingWireless smoke and CO detectorsHVAC controlHeating controlHome securityEnvironmental controlsBlind, drapery and shade controlsMedical sensing and monitoringUniversal Remote Control to a Set-Top Box which includes Home ControlIndustrial automationBuilding automation
Advantages:
Battery life in Zigbee technology is more (1000+days).Transmission range will be 100+ meters .System resources are very comfortable within 20KB.Network size is unlimited .High reliability ,low power and low cost.Very low duty cycle.
Disadvantages:
When compared to other technologies data rate is low in Zigbee.Bandwidth is low.
Conclusion:
The ZigBee Alliance is a global ecosystem of companies creating wireless solutions for use in residential commercial and industrial applications. The ZigBee Alliance companies work together to enable reliable, cost effective, low power, wirelessly networked, monitoring and control products based on an open global standard. The ZigBee Alliance membership comprises technology providers and original equipment manufacturers world wide.
