Zigbee

ZIGBEE

SMART WIRELESS NETWORK

ZIGBEE TECHNOLOGY

ZigBee is the only standards-based wireless technology designed to address the unique needs of low-cost, low-power wireless sensor and control networks in just about any market. This paper aims at presenting the concept of ZigBee, the name of a specification for a suite of high level communication protocols using small, low-power digital radios based on the IEEE 802.15.4-2006 standard for wireless personal area networks (WPANs), such as wireless headphones connecting with cell phones via short-range radio. The technology is intended to be simpler and less expensive than other WPANs, such as Bluetooth. ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.

INTRODUCTION

ü  ZigBee is a specification for a suite of high level communication protocols using small, low-power digital radios based on an IEEE 802.15.4 standard for personal area networks.

ü  802 is the group which is a section of IEEE and is involved in the technologies and network operations which include local networks and mid size networks. The Group 15 specifically deals with the wireless network technologies and it also includes the Bluetooth group.

ü  The technology defined by the ZigBee specification is intended to be simpler and less expensive than other WPANs, such as Bluetooth.

ü  ZigBee is targeted at radio-frequency (RF) applications that require a low data rate, long battery life, and secure networking.

ü  ZigBee has a defined rate of 250 kbps best suited for periodic or intermittent data or a single signal transmission from a sensor or input device.

ü  The name refers to the waggle dance of honey bees after their return to the beehive.

1. TECHNICAL OVERVIEW.

ü  ZigBee is a low-cost, low-power, wireless mesh network standard.

ü  The low cost allows the technology to be widely deployed in wireless control and monitoring applications.

ü  Low power-usage allows longer life with smaller batteries.

ü  Mesh networking provides high reliability and more extensive range.

ü  ZigBee chip vendors typically sell integrated radios and microcontrollers with between 60 KB and 256 KB flash memory.

ü  Operates in the industrial, scientific and medical (ISM) radio bands; 868 MHz in Europe, 915 MHz in the USA and Australia, and 2.4 GHz in most jurisdictions worldwide. Data transmission rates vary from 20 to 900 kilobits/second.

2. COMPARISION WITH BLUETOOTH:

BLUETOOTH	ZIGBEE
Focuses mainly on the connectivity between the large packet devices.	Designed mainly to provide high and efficient connectivity in small packet devices.
Provides operations which are complex	Provides operations which are actually less complex.
Direct Sequence Spread Spectrum 250kb/s	Frequency Hopping Spread Spectrum 720kb/s
As a Mobile Phone Regular Charging	2+ years from ‘normal’ batteries
Bluetooth wake-up delays, which are typically around three seconds.	ZigBee nodes can go from sleep to active mode in 30 ms or less, the latency can be low and devices can be responsive.

3. DEVICE TYPES

There are three different types of ZigBee devices:

ü  ZigBee coordinator (ZC): The most capable device, the coordinator forms the root of the network tree and might bridge to other networks. There is exactly one ZigBee coordinator in each network since it is the device that started the network originally. It is able to store information about the network, including acting as the Trust Center & repository for security keys.^[13][14]

ü  ZigBee Router (ZR): As well as running an application function, a router can act as an intermediate router, passing on data from other devices.

ü  ZigBee End Device (ZED): Contains just enough functionality to talk to the parent node (either the coordinator or a router); it cannot relay data from other devices. This relationship allows the node to be asleep a significant amount of the time thereby giving long battery life. A ZED requires the least amount of memory, and therefore can be less expensive to manufacture than a ZR or ZC.

4. NETWORK  DESIGN:

The ZigBee network layer natively supports both star and tree typical networks, and generic mesh networks. Every network must have one coordinator device, tasked with its creation, the control of its parameters and basic maintenance. Within star networks, the coordinator must be the central node. Both trees and meshes allows the use of ZigBee routers to extend communication at the network level.

5. APPLICATIONS

Wireless connectivity is also making in roads into energy management by enabling communication between utility meters, lighting, HVAC and appliances to control and monitor energy consumption reducing peak demand for utility companies and reducing energy cost for the consumers.

ü  Commercial systems: Building management and control, vending machines, fleet management, kiosk.

ü  Enterprise systems: Health care and patient monitoring, environmental monitoring and detection.

ü  Military and government systems: Asset tracking, personal monitoring and surveillance.

ü  Transportation systems: Audio control and automation, security and access control.

INDUSTRIAL USE

P  Automated meter reading (AMR) for utility and energy management, Logistics and inventory tracking,

P   Security and access control.

P  Systems tracking for preventive maintenance and performance monitoring.

P  Seismic detectors.

P   Inclinometers.

P  Robotics.

6. CLOSING THOUGHT

“Just as the personal computer was a symbol of the '80s, and the symbol of the '90s is the World Wide Web, the next nonlinear shift, is going to be the advent of cheap sensors.”

-Paul Saffo

Institute for the Future

REFERENCES

[1] Indian Journal of Science and Technology     by P.Ramanathan & P.Manjrekar                                                                                                     

[2] Hands-On Zigbee: Implementing 802.15.4 with Microcontrollers (Embedded Technology) by Fred Eady  

[3] Zigbee Resource Guide by Zigbee Alliance Members

[4] Wireless Sensor Networks: Architectures and Protocols by Edgar H. Callaway, Jr., Auerbach Publications, 2003