| Overview ZigBee is a low-cost, low-power, wireless | | | | constantly, since it is connected to the mains supply, |
| mesh networking proprietary standard. The low cost | | | | while a battery-powered light switch would remain |
| allows the technology to be widely deployed in | | | | asleep until the switch is thrown. The switch then |
| wireless control and monitoring applications, the low | | | | wakes up, sends a command to the lamp, receives an |
| power-usage allows longer life with smaller batteries, | | | | acknowledgment, and returns to sleep. In such a |
| and the mesh networking provides high reliability and | | | | network the lamp node will be at least a ZigBee |
| larger range. The ZigBee Alliance, the standards body | | | | Router, if not the ZigBee Coordinator; the switch node |
| that defines ZigBee, also publishes application profiles | | | | is typically a ZigBee End Device. In beacon-enabled |
| that allow multiple OEM vendors to create | | | | networks, the special network nodes called ZigBee |
| interoperable products. The current list of application | | | | Routers transmit periodic beacons to confirm their |
| profiles either published or in the works are: Home | | | | presence to other network nodes. Nodes may sleep |
| Automation ZigBee Smart Energy Commercial Building | | | | between beacons, thus lowering their duty cycle and |
| Automation Telecommunication Applications Personal, | | | | extending their battery life. Beacon intervals may range |
| Home, and Hospital Care Toys The relationship | | | | from 15.36 milliseconds to 15.36 ms * 214 = 251.65824 |
| between IEEE 802.15.4 and ZigBee is similar to that | | | | seconds at 250 kbit/s, from 24 milliseconds to 24 ms * |
| between IEEE 802.11 and the Wi-Fi Alliance. The | | | | 214 = 393.216 seconds at 40 kbit/s and from 48 |
| ZigBee 1.0 specification was ratified on 14 December | | | | milliseconds to 48 ms * 214 = 786.432 seconds at 20 |
| 2004 and is available to members of the ZigBee | | | | kbit/s. However, low duty cycle operation with long |
| Alliance. Most recently, the ZigBee 2007 specification | | | | beacon intervals requires precise timing, which can |
| was posted on 30 October 2007. The first ZigBee | | | | conflict with the need for low product cost. In general, |
| Application Profile, Home Automation, was announced | | | | the ZigBee protocols minimize the time the radio is on |
| 2 November 2007. ZigBee operates in the industrial, | | | | so as to reduce power use. In beaconing networks, |
| scientific and medical (ISM) radio bands; 868 MHz in | | | | nodes only need to be active while a beacon is being |
| Europe, 915 MHz in the USA and Australia, and | | | | transmitted. In non-beacon-enabled networks, power |
| 2.4 GHz in most jurisdictions worldwide. The | | | | consumption is decidedly asymmetrical: some devices |
| technology is intended to be simpler and less | | | | are always active, while others spend most of their |
| expensive than other WPANs such as Bluetooth. | | | | time sleeping. ZigBee devices are required to conform |
| ZigBee chip vendors typically sell integrated radios and | | | | to the IEEE 802.15.4-2003 Low-Rate Wireless Personal |
| microcontrollers with between 60K and 128K flash | | | | Area Network (WPAN) standard. The standard |
| memory, such as the Jennic JN5148, the Freescale | | | | specifies the lower protocol layershe physical layer |
| MC13213, the Ember EM250, the Texas Instruments | | | | (PHY), and the media access control (MAC) portion of |
| CC2430, the Samsung Electro-Mechanics ZBS240 | | | | the data link layer (DLL). This standard specifies |
| and the Atmel ATmega128RFA1. Radios are also | | | | operation in the unlicensed 2.4 GHz (worldwide), |
| available stand-alone to be used with any processor or | | | | 915 MHz (Americas) and 868 MHz (Europe) ISM |
| microcontroller. Generally, the chip vendors also offer | | | | bands. In the 2.4 GHz band there are 16 ZigBee |
| the ZigBee software stack, although independent ones | | | | channels, with each channel requiring 5 MHz of |
| are also available. Because ZigBee can activate (go | | | | bandwidth. The center frequency for each channel |
| from sleep to active mode) in 15 msec or less, the | | | | can be calculated as, FC = (2405 + 5 * (ch - 11)) MHz, |
| latency can be very low and devices can be very | | | | where ch = 11, 12, ..., 26. The radios use direct-sequence |
| responsive particularly compared to Bluetooth | | | | spread spectrum coding, which is managed by the |
| wake-up delays, which are typically around three | | | | digital stream into the modulator. BPSK is used in the |
| seconds. Because ZigBees can sleep most of the | | | | 868 and 915 MHz bands, and OQPSK that transmits |
| time, average power consumption can be very low, | | | | two bits per symbol is used in the 2.4 GHz band. The |
| resulting in long battery life. The first stack release is | | | | raw, over-the-air data rate is 250 kbit/s per channel in |
| now called ZigBee 2004. The second stack release is | | | | the 2.4 GHz band, 40 kbit/s per channel in the |
| called ZigBee 2006, and mainly replaces the MSG | | | | 915 MHz band, and 20 kbit/s in the 868 MHz band. |
| KVP structure used in 2004 with a "cluster library". The | | | | Transmission range is between 10 and 75 meters (33 |
| 2004 stack is now more or less obsolete.[citation | | | | and 246 feet) and up to 1500 meters for zigbee pro, |
| needed] ZigBee 2007, now the current stack release, | | | | although it is heavily dependent on the particular |
| contains two stack profiles, stack profile 1 (simply | | | | environment. The maximum output power of the |
| called ZigBee), for home and light commercial use, and | | | | radios is generally 0 dBm (1 mW). The basic channel |
| stack profile 2 (called ZigBee Pro). ZigBee Pro offers | | | | access mode is "carrier sense, multiple access/collision |
| more features, such as multi-casting, many-to-one | | | | avoidance" (CSMA/CA). That is, the nodes talk in the |
| routing and high security with Symmetric-Key Key | | | | same way that people converse; they briefly check to |
| Exchange (SKKE), while ZigBee (stack profile 1) offers | | | | see that no one is talking before they start. There are |
| a smaller footprint in RAM and flash. Both offer full | | | | three notable exceptions to the use of CSMA. |
| mesh networking and work with all ZigBee application | | | | Beacons are sent on a fixed timing schedule, and do |
| profiles.[citation needed] ZigBee 2007 is fully backward | | | | not use CSMA. Message acknowledgments also do |
| compatible with ZigBee 2006 devices: A ZigBee 2007 | | | | not use CSMA. Finally, devices in Beacon Oriented |
| device may join and operate on a ZigBee 2006 | | | | networks that have low latency real-time requirements |
| network and vice versa. Due to differences in routing | | | | may also use Guaranteed Time Slots (GTS), which by |
| options, ZigBee Pro devices must become non-routing | | | | definition do not use CSMA. ZigBee RF4CE On March |
| ZigBee End-Devices (ZEDs) on a ZigBee 2006 or | | | | 3, 2009 the RF4CE (Radio Frequency for Consumer |
| ZigBee 2007 network, the same as ZigBee 2006 or | | | | Electronics) Consortium agreed to work with the |
| ZigBee 2007 devices must become ZEDs on a | | | | ZigBee Alliance to jointly deliver a standardized |
| ZigBee Pro network. The applications running on those | | | | specification for radio frequency-based remote |
| devices work the same, regardless of the stack profile | | | | controls. ZigBee RF4CE is designed to be deployed in |
| beneath them. Licensing For non-commercial purposes, | | | | a wide range of remotely-controlled audio/visual |
| the ZigBee specification is available free to the general | | | | consumer electronics products, such as TVs and |
| public. An entry level membership in the ZigBee | | | | set-top boxes. It promises many advantages over |
| Alliance, called Adopter, provides access to the as-yet | | | | existing remote control solutions, including richer |
| unpublished specifications and permission to create | | | | communication and increased reliability, enhanced |
| products for market using the specifications. The click | | | | features and flexibility, interoperability, and no |
| through license on the ZigBee specification requires a | | | | line-of-sight barrier. Software and hardware The |
| commercial developer to join the ZigBee Alliance. "No | | | | software is designed to be easy to develop on small, |
| part of this specification may be used in development | | | | inexpensive microprocessors. The radio design used |
| of a product for sale without becoming a member of | | | | by ZigBee has been carefully optimized for low cost in |
| ZigBee Alliance." The annual fee conflicts with the | | | | large scale production. It has few analog stages and |
| GNU General Public License. From the GPL v2, "b) | | | | uses digital circuits wherever possible. Even though the |
| You must cause any work that you distribute or | | | | radios themselves are inexpensive, the ZigBee |
| publish, that in whole or in part contains or is derived | | | | Qualification Process involves a full validation of the |
| from the Program or any part thereof, to be licensed | | | | requirements of the physical layer. This amount of |
| as a whole at no charge to all third parties under the | | | | concern about the Physical Layer has multiple benefits, |
| terms of this License." Since the GPL makes no | | | | since all radios derived from that semiconductor mask |
| distinction between commercial and non-commercial | | | | set would enjoy the same RF characteristics. On the |
| use it is impossible to implement a GPL licensed | | | | other hand, an uncertified physical layer that |
| ZigBee stack or combine a ZigBee implementation | | | | malfunctions could cripple the battery lifespan of other |
| with GPL licensed code. The requirement for the | | | | devices on a ZigBee network. Where other protocols |
| developer to join the ZigBee Alliance similarly conflicts | | | | can mask poor sensitivity or other esoteric problems in |
| with most other Free software licenses. Uses ZigBee | | | | a fade compensation response, ZigBee radios have |
| protocols are intended for use in embedded | | | | very tight engineering constraints: they are both power |
| applications requiring low data rates and low power | | | | and bandwidth constrained. Thus, radios are tested to |
| consumption. ZigBee's current focus is to define a | | | | the ISO 17025 standard with guidance given by Clause |
| general-purpose, inexpensive, self-organizing mesh | | | | 6 of the 802.15.4-2006 Standard. Most vendors plan to |
| network that can be used for industrial control, | | | | integrate the radio and microcontroller onto a single |
| embedded sensing, medical data collection, smoke and | | | | chip. History ZigBee-style networks began to be |
| intruder warning, building automation, home automation, | | | | conceived about 1998, when many installers realized |
| etc. The resulting network will use very small amounts | | | | that both WiFi and Bluetooth were going to be |
| of power individual devices must have a battery life | | | | unsuitable for many applications. In particular, many |
| of at least two years to pass ZigBee certification. | | | | engineers saw a need for self-organizing ad-hoc digital |
| Typical application areas include Home Entertainment | | | | radio networks. The IEEE 802.15.4 standard was |
| and Control Smart lighting, advanced temperature | | | | completed in May 2003.[citation needed] In the summer |
| control, safety and security, movies and music Home | | | | of 2003, Philips Semiconductors, a major mesh |
| Awareness Water sensors, power sensors, energy | | | | network supporter, ceased the investment. Philips |
| monitoring, smoke and fire detectors, smart appliances | | | | Lighting has, however, continued Philips' participation, |
| and access sensors Mobile Services m-payment, | | | | and Philips remains a promoter member on the ZigBee |
| m-monitoring and control, m-security and access | | | | Alliance Board of Directors.[citation needed] The |
| control, m-healthcare and tele-assist Commercial | | | | ZigBee Alliance announced in October 2004 that the |
| Building Energy monitoring, HVAC, lighting, access | | | | membership had more than doubled in the preceding |
| control Industrial Plant Process control, asset | | | | year and had grown to more than 100 member |
| management, environmental management, energy | | | | companies, in 22 countries. By April 2005 membership |
| management, industrial device control Device types | | | | had grown to more than 150 companies, and by |
| There are three different types of ZigBee devices: | | | | December 2005 membership had passed 200 |
| ZigBee coordinator (ZC): The most capable device, the | | | | companies.[citation needed] The ZigBee specifications |
| coordinator forms the root of the network tree and | | | | were ratified on 14 December 2004.[citation needed] |
| might bridge to other networks. There is exactly one | | | | The ZigBee Alliance announces public availability of |
| ZigBee coordinator in each network since it is the | | | | Specification 1.0 on 13 June 2005, known as ZigBee |
| device that started the network originally. It is able to | | | | 2004 Specification. The ZigBee Alliance announces the |
| store information about the network, including acting as | | | | completion and immediate member availability of the |
| the Trust Centre & repository for security keys. | | | | enhanced version of the ZigBee Standard in |
| ZigBee Router (ZR): As well as running an application | | | | September 2006, known as ZigBee 2006 |
| function, a router can act as an intermediate router, | | | | Specification. During the last quarter of 2007, ZigBee |
| passing on data from other devices. ZigBee End | | | | PRO, the enhanced ZigBee specification was |
| Device (ZED): Contains just enough functionality to talk | | | | finalized.[citation needed] Origins of ZigBee name |
| to the parent node (either the coordinator or a router); | | | | Articles published by technology news organizations |
| it cannot relay data from other devices. This | | | | such as EDN See also 6loWPAN Comparison of |
| relationship allows the node to be asleep a significant | | | | 802.15.4 radio modules Comparison of wireless data |
| amount of the time thereby giving long battery life. A | | | | standards DASH7 EnOcean Internet 0 Insteon |
| ZED requires the least amount of memory, and | | | | NeuRFon ONE-NET Wibree Z-Wave ZigBee |
| therefore can be less expensive to manufacture than | | | | specification References ^ "Our Mission". zigbee.org. |
| a ZR or ZC. Protocols The protocols build on recent | | | | Retrieved 2009-07-11. ^ ZigBee: Wireless Technology |
| algorithmic research (Ad-hoc On-demand Distance | | | | for Low-Power Sensor Networks ^ "ZigBee |
| Vector, neuRFon) to automatically construct a | | | | Specification Download Request". zigbee.org. |
| low-speed ad-hoc network of nodes. In most large | | | | Retrieved 2009-04-15. ^ "Zigbee, Linux, and the GPL". |
| network instances, the network will be a cluster of | | | | freaklabs.org. Retrieved 2009-06-14. ^ ^ "What's so |
| clusters. It can also form a mesh or a single cluster. | | | | good about ZigBee networks?". Daintree Networks. |
| The current profiles derived from the ZigBee protocols | | | | Retrieved 2007-01-19. ^ "Introducing ZigBee RF4CE". |
| support beacon and non-beacon enabled networks. In | | | | Daintree Networks. Retrieved 2009-05-04. ^ {{cite |
| non-beacon-enabled networks (those whose beacon | | | | web|url= External links ZigBee Alliance homepage IEEE |
| order is 15), an unslotted CSMA/CA channel access | | | | 802.15.4 web site ZigBee Suppliers ZigBee Review |
| mechanism is used. In this type of network, ZigBee | | | | and comparison to other home automation |
| Routers typically have their receivers continuously | | | | technologies ZigBee Resources including whitepapers |
| active, requiring a more robust power supply. However, | | | | and specification updates FreakZ open source ZigBee |
| this allows for heterogeneous networks in which some | | | | project, Project homepage, and ZigBee/802.15.4 chip |
| devices receive continuously, while others only transmit | | | | comparison Java XBee API (under GPLv3) zPoint |
| when an external stimulus is detected. The typical | | | | Products offers a suite of ZigBee devices XBee |
| example of a heterogeneous network is a wireless | | | | Library for the .NET Micro Framework Toolkit .NET |
| light switch: The ZigBee node at the lamp may receive | | | | API Library for XBee 2. |