Zigbee

ZigBee is an established set of specifications for wireless personal area networking (WPAN), i.e. digital radio connections between computers and related devices.

676 Views, 03 Nov 2017 05:52 pm

Description

Zigbee

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 one of the global standards of communication protocol formulated by the relevant task force under the IEEE 802.15 working group. The fourth in the series, WPAN Low Rate/ZigBee is the newest and provides specifications for devices that have low data rates, consume very low power and are thus characterized by long battery life. Other standards like Bluetooth and IrDA address high data rate applications such as voice, video and LAN communications.

The ZigBee Alliance has been set up as “an association of companies working together to enable reliable, cost-effective, low-power, wirelessly networked, monitoring and control products based on an open global standard”.

Once a manufacturer enrolls in this Alliance for a fee, he can have access to the standard and implement it in his products in the form of ZigBee chipsets that would be built into the end devices. Philips, Motorola, Intel, HP are all members of the Alliance . The goal is “to provide the consumer with ultimate flexibility, mobility, and ease of use by building wireless intelligence and capabilities into every day devices. ZigBee technology will be embedded in a wide range of products and applications across consumer, commercial, industrial and government markets worldwide. For the first time, companies will have a standards-based wireless platform optimized for the unique needs of remote monitoring and control applications, including simplicity, reliability, low-cost and low-power”.

The target networks encompass a wide range of devices with low data rates in the Industrial, Scientific and Medical (ISM) radio bands, with building-automation controls like intruder/fire alarms, thermostats and remote (wireless) switches, video/audio remote controls likely to be the most popular applications. So far sensor and control devices have been marketed as proprietary items for want of a standard. With acceptance and implementation of ZigBee, interoperability will be enabled in multi-purpose, self-organizing mesh networks

Application of ZigBee


  •        Monitoring and control of lights, HVAC, and security in commercial buildings
  •        Industrial monitoring and control, with sensors and actuators in manufacturing, process control, farming, environmental, and other areas
  •        Automatic meter reading (AMR) with load management, enabling the utility industry to cut costs and save electrical and gas energy
  •        Oil and gas production, transmission, and exploration with supervisory control and data acquisition (SCADA) as well as other telemetry
  •        Home monitoring and control of lights, HVAC, security, and other systems
  •        Medical and health monitoring of patients, equipment, and facilities
  •        Military, with battlefield monitoring and robotic control
  •        Automotive, with sensor networks to report on the status of all systems
  •        Consumer, with remote control of toys, games, TV, stereo, DVD, stereo, and appliances
  •        Computer peripherals, such as the mouse, keyboard, game controllers, and printer
  •        Active RFID, with battery-powered tags for shipping, tracking, and storing larger items and asset management
  •        Machine-to-machine (M2M) communications between devices via the Internet


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