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O que é ZigBee?
ZigBee é um padrão que será definido por uma aliança de empresas
de diferentes segmentos do mercado, chamada "ZigBee Alliance".
Este protocolo permite comunicação sem fio confiável, com baixo
consumo de energia e baixas taxas de transmissão para aplicações
de monitoramento e controle. Para implementar as camadas MAC (Medium
Access Control) e PHY (Physical Layer) o ZigBee utiliza a
definição 802.15.4 do IEEE, que opera em bandas de freqüência
livres. [Fonte:
Tutorial do site Teleco]
[27/12/04]
Notícias
2006:
Setembro -
Agosto
Artigos
2. IEEE 802.15.4
3. Zig Bee
4. Zig Bee X BlueThooth
5. Aplicações
6. Conclusões
7. ReferênciasFonte: Radio-Eletronics.com
Zigbee and IEEE 802.15.4 for remote data, sensor
and control applications
WiseGeek
What is ZigBee?
Transcrições
Fonte: Radio-Eletronics.com
Zigbee and IEEE 802.15.4 for remote data, sensor and
control applications
Zigbee is a wireless networking standard that is aimed at remote control and sensor applications which is suitable for operation in harsh radio environments and in isolated locations. It builds on IEEE standard 802.15.4 which defines the physical and MAC layers. Above this, Zigbee defines the application and security layer specifications enabling interoperability between products from different manufacturers. In this way Zigbee is a superset of the 802.15.4 specification.
With the applications for remote wireless sensing and control growing rapidly it is estimated that the market size could reach hundreds of millions of dollars as early as 2007. This makes Zigbee a very attractive proposition, and one which warrants the introduction of a focussed standard.
Zigbee organisation
The Zigbee standard is organised under the auspices of the Zigbee Alliance. This organisation has over seventy members, of which five have taken on the status of what they term "promoter." These five companies are Ember, Honeywell, Invensys, Mitsubishi, Motorola, Philips, and Samsung. Under the umbrella of the Zigbee Alliance, the new standard will be pushed forward, taking on board the requirements of the users, manufacturers and the system developers.
Basics
The distances that can be achieved transmitting from one station to the next extend up to about 70 metres, although very much greater distances may be reached by relaying data from one node to the next in a network.
The main applications for 802.15.4 are aimed at control and monitoring applications where relatively low levels of data throughput are needed, and with the possibility of remote, battery powered sensors, low power consumption is a key requirement. Sensors, lighting controls, security and many more applications are all candidates for the new technology.
Physical and MAC layers
The system is specified to operate in one of the three license free bands at 2.4 GHz, 915 MHz for North America and 868 MHz for Europe. In this way the standard is able to operate around the globe, although the exact specifications for each of the bands are slightly different. At 2.4 GHz there are a total of sixteen different channels available, and the maximum data rate is 250 kbps. For 915 MHz there are ten channels and the standard supports a maximum data rate of 40 kbps, while at 868 MHz there is only one channel and this can support data transfer at up to 20 kbps.
The modulation techniques also vary according to the band in use. Direct sequence spread spectrum (DSSS) is used in all cases. However for the 868 and 915 MHz bands the actual form of modulation is binary phase shift keying. For the 2.4 GHz band, offset quadrature phase shift keying (O-QPSK) is employed.
In view of the fact that systems may operate in heavily congested environments, and in areas where levels of extraneous interference is high, the 802.15.4 specification has incorporated a variety of features to ensure exceedingly reliable operation. These include a quality assessment, receiver energy detection and clear channel assessment. CSMA (Carrier Sense Multiple Access) techniques are used to determine when to transmit, and in this way unnecessary clashes are avoided.
Data transfer
The data is transferred in packets. These have a maximum size of 128 bytes, allowing for a maximum payload of 104 bytes. Although this may appear low when compared to other systems, the applications in which 802.15.4 and Zigbee are likely to be used should not require very high data rates.
The standard supports 64 bit IEEE addresses as well as 16 bit short addresses. The 64 bit addresses uniquely identify every device in the same way that devices have a unique IP address. Once a network is set up, the short addresses can be used and this enables over 65000 nodes to be supported.
It also has an optional superframe structure with a method for time synchronisation. In addition to this it is recognised that some messages need to be given a high priority. To achieve this, a guaranteed time slot mechanism has been incorporated into the specification. This enables these high priority messages to be sent across the network as swiftly as possible.
Upper layers (Zigbee)
Above the physical and MAC layers defined by 802.15.4, the Zigbee standard itself defines the upper layers of the system. This includes many aspects including the messaging, the configurations that can be used, along with security aspects and the application profile layers.
There are three different network topologies that are supported by Zigbee, namely the star, mesh and cluster tree or hybrid networks. Each has its own advantages and can be used to advantage in different situations.
The star network is commonly used, having the advantage of simplicity. As the name suggests it is formed in a star configuration with outlying nodes communicating with a central node.
Mesh or peer to peer networks enable high degrees of reliability to be obtained. They consist of a variety of nodes placed as needed, and nodes within range being able to communicate with each other to form a mesh. Messages may be routed across the network using the different stations as relays. There is usually a choice of routes that can be used and this makes the network very robust. If interference is present on one section of a network, then another can be used instead.
Finally there is what is known as a cluster tree network. This is essentially a combination of star and mesh topologies.
Both 802.15.4 and Zigbee have been optimised to ensure that low power consumption is a key feature. Although nodes with sensors of control mechanisms towards the centre of a network are more likely to have mains power, many towards the extreme may not. The low power design has enabled battery life to be typically measured in years, enabling the network not to require constant maintenance.
Summary
Although there is an increasing number of wireless standards that are appearing, Zigbee has a distinct area upon which it is focussed. It is not inteneded to compete with standards such as 802.11, Bluetooth and the like. Instead it has been optimised to ensure that it meets its intended requirements, fulfilling the needs for remote control and sensing applications.
WiseGeek
What is ZigBee?
ZigBee is the set of specs built around the IEEE 802.15.4 wireless protocol. The
IEEE is the Institute of Electrical and Electronics Engineers. They are a
non-profit organization dedicated to furthering technology involving electronics
and electronic devices. The 802 group is the section of the IEEE involved in
network operations and technologies, including mid-sized networks and local
networks. Group 15 deals specifically with wireless networking technologies, and
includes the now ubiquitous 802.15.1 working group, which is also known as
Bluetooth.
The name "ZigBee" is derived from the erratic zigging patterns many bees make
between flowers when collecting pollen. This is evocative of the invisible webs
of connections existing in a fully wireless environment. The standard itself is
regulated by a group known as the ZigBee Alliance, with over 150 members
worldwide.
While Bluetooth focuses on connectivity between large packet user devices, such
as laptops, phones, and major peripherals, ZigBee is designed to provide highly
efficient connectivity between small packet devices. As a result of its
simplified operations, which are one to two full orders of magnitude less
complex than a comparable Bluetooth device, pricing for ZigBee devices is
extremely competitive, with full nodes available for a fraction of the cost of a
Bluetooth node.
ZigBee devices are actively limited to a through-rate of 250Kbps, compared to
Bluetooth's much larger pipeline of 1Mbps, operating on the 2.4 GHz ISM band,
which is available throughout most of the world.
ZigBee has been developed to meet the growing demand for capable wireless
networking between numerous low-power devices. In industry ZigBee is being used
for next generation automated manufacturing, with small transmitters in every
device on the floor, allowing for communication between devices to a central
computer. This new level of communication permits finely-tuned remote monitoring
and manipulation. In the consumer market ZigBee is being explored for everything
from linking low-power household devices such as smoke alarms to a central
housing control unit, to centralized light controls.
The specified maximum range of operation for ZigBee devices is 250 feet (76m),
substantially further than that used by Bluetooth capable devices, although
security concerns raised over "sniping" Bluetooth devices remotely, may prove to
hold true for ZigBee devices as well.
Due to its low power output, ZigBee devices can sustain themselves on a small
battery for many months, or even years, making them ideal for install-and-forget
purposes, such as most small household systems. Predictions of ZigBee
installation for the future, most based on the explosive use of ZigBee in
automated household tasks in China, look to a near future when upwards of sixty
ZigBee devices may be found in an average American home, all communicating with
one another freely and regulating common tasks seamlessly.
Transcrições de Notícias
[29/03/06]
Siemens abraça padrão wireless ZigBee
São Paulo, 28 de março de 2006 - A Siemens,
um dos maiores expoentes mundiais da indústria eletro-eletrônica, acaba de ser
promovida a membro "promotor", o mais alto nível dentro da ZigBee Alliance e
que ainda dá direito a uma cadeira na mesa diretora da entidade. Emulando a
"batalha" entre o
Linux e o Windows, o ZigBee é a resposta opensource ao Bluetooth, sistema
wireless inventado pela sueca Ericsson nos anos 90.
Apesar do atual domínio do
Bluetooth no mercado, a investida da Siemens acompanha os passos já dados
por outros gigantes da indústria como a Philips, Mitsubish, Motorola,
Honeywell, Freescale, Samsung, Texas Intruments, entre outros. Todas essas
empresas contam com representantes na mesa diretora da ZigBee Alliance, ,
associação sem fins lucrativos que tem como missão
divulgar o padrão de intercomunicação sem fios para dispositivos
eletrônicos ZigBee.
Segundo Marcus Torchia, analista sênior da
divisão de negócios móveis/sem fio da consultoria Yankee Group, "a ZigBee
Alliance já provou seu comprometimento com qualidade e interoperabilidade. A
entrada da Siemens no hall das empresas promotoras demonstra o grande
compromisso da indústria em dar suporte e desenvolver aplicativos para o
ZigBee".
"A Siemens investigou detalhadamente as
diversas opções de controle wireless disponíveis no mercado e selecionou o
ZigBee porque oferece um padrão reconhecido internacionalmente que se encaixa
bem nas estratégias de produto em várias de nossas unidades de negócio", disse
Walter Veigel, vice-presidente de padronização e regulamentação da Siemens AG.
"Nossa expertise no campo da automação vai beneficiar o ZigBee nos próximos
anos".
A empresa promete que vai implementar a
tecnologia em sensores utilizados em sistema discretos de manufatura e na
automação de processos, juntamente com os padrões de comunicação já
implantados. Mais informações, em inglês, podem ser obtidas no site da
ZigBee Alliance.
[27/02/04]
ZigBee e WUSB extinguirão o Bluetooth?
Verissimo enviou "Estão chegando a nosso conhecimento os padrões
de WPAN (wireless personal area networks) conhecidos como ZigBee
e WUSB (Wireless USB).
O ZigBee foi lançado em 2003, mas só agora a idéia aporta na
Ilha de Vera Cruz. O WUSB é esperado para o início de 2005.
ZigBee é um padrão homologado pelo IEEE sob o numero 802.15.4 e
já tem até sua aliança: a ZigBee Alliance (http://www.zigbee.com/).
ZigBee é um padrão que visa ter baixo custo, baixa potência e
confiabilidade. A Aliança ajuda na instalação de sistemas
confiáveis, segurança robusta, baterias de "vida longa" e
latência de dados ajustável. O ZigBee é um protocolo wireless de
baixo consumo e baixa velocidade (o limite superior da taxa de
transmissão dele é de 250 Kilobits por segundo). O ZigBee atende
a Rede de Sensores, Controles Remotos, etc...
No lado oposto do time de padrões de WPAN estão as Wireless USB.
Tem a mesma idéia das conexões USB wired que temos hoje, só que
via rádio. WUSB pode chegar até 480 Mbps, bem mais do que o
1Mbps do Bluetooth, banda suficiente para ligar uma câmera de
vídeo.
A ZigBee Alliance corre para justificar a coexistência do ZigBee
e Bluetooth em http://www.zigbee.org/resources/documents/ZigBeeBluetoothComparison4.pdf,
enfatisando que o ZigBee foi idealizado para trabalhar em redes
de sensores, reagindo a consultas. A coexistência do Bluetooth
com o WUSB é mais clara, visto que a primeira tecnologia, assim
como o ZigBee, tem custo idealizado em Us$ 5,00, mais barato do
que se espera para a tecnologia WUSB.
Pelo visto teremos opções. Se ter várias opções será bom ou não,
veremos num futuro próximo. O certo é que cada aplicação tem a
sua aplicação.
Fernando Verissimo :
http://www.pobox.com/~verissimo
Referências
Wireless USB Spec Revealed
www.cellular.co.za/ news_2003/121903-wireless_usb_spec_revealed.htm. Visitado em 27/fev/04
ZigBee Alliance
http://www.zigbee.com. Visitado em 27/fev/04
The Official Bluetooth Website
http://www.bluetooth.com/. Visitado em 27/fev/04
Caderno Link do
Estadão
[19/09/05]
Sistema controla aparelhos da casa via celular
Nokia, Mitsubishi, Freescale e Compera unem tecnologias em
produto para condomínios
Uma nova solução para controlar os equipamentos da casa a
distância pelo telefone celular será apresentada conjuntamente
pela Nokia, Mitsubishi, Freescale e Compera na Febrava, feira
que começa amanhã, no Centro de Exposições Imigrantes, em São
Paulo.
Segundo Luiz Tadashi Akuta, gerente de Automação Industrial da
Mitsubishi, até agora controlar os equipamentos da casa era
possível por meio de transmissão de dados GPRS. “A troca de
informações entre os equipamentos podia demorar vários
segundos”, diz. A solução desenvolvida pelas quatro empresas
utiliza tecnologia sem fio e mensagens SMS.
O sistema funciona por meio da rede sem fio ZigBee, da Freescale
Semicondutores. Os celulares 6681 e 6600 da Nokia são
compatíveis com a solução e possuem um menu com as funções em
forma de desenhos para controlar a iluminação, o ar condicionado
e o alarme. O usuário ativa o comando, e o celular envia uma
mensagem codificada em mensagem SMS para o modem controlador da
Mitsubishi, instalado na residência.
Esse modem GSM reconhece os códigos e distribui os comandos via
rede sem fio para os equipamentos que foram selecionados pelo
usuário. Os chips ZigBee podem habilitar qualquer tipo de
aparelho eletrônico para várias aplicações, como monitoramento,
automação e controle de residências. As aplicações podem ser
feitas em aquecedores, banheiras, entre outros.
O sistema que será apresentado na Febrava já está à venda. “A
vantagem é que a rede sem fio ZigBee não necessita quebrar as
paredes de uma casa pronta”, ressalta Antonio Calmon, diretor da
Freescale.
Outra vantagem é a economia de energia. “Em vez de deixar o
ar-condicionado ligado o dia inteiro para chegar em casa e o
ambiente estar refrigerado, basta ligar pelo celular uma hora
antes de chegar”, explica Akuta, da Mitsubishi.
O morador ainda pode verificar, pela Nokia Remote Camera, a
movimentação das pessoas na rua antes de chegar em casa. No Rio
de Janeiro, um prédio já está vendendo o pacote dessa tecnologia
para quem compra o apartamento. A instalação varia de R$ 15 mil
a R$ 20 mil. C.G.
[17/07/06]
ZigBee Turns Up the
Temperature
By Glenn Fleishman
Wireless Week reports that the low-power, long-lived ZigBee
standard is gaining momentum: ZigBee (802.15.4) is designed to
provide small amounts of information over a very long period so
that it can be embedded as radio technology in sensors and
remote controls. The idea is that devices that otherwise would
require wires in order to produce readings could deliver
telemetry or send very small control strings and not require
battery changes for many months or even years.
If ZigBee became widespread, it would dramatically reduce the
need for wiring for heating/cooling in hotels and office
buildings (and eventually in homes). It would also allow many
incompatible systems to be replaced with one simple standard
that will be cost effective to manufacture in bulk.
Right now, ZigBee single chip chipsets are $3 to $5. It needs to
get below a buck. Ethernet inventor Bob Metcalfe, the chairman
of a key chipmaker, noted that 10b microcontrollers are sold
every year, and ZigBee could be significant part of that market.
World’s
First Mobile Phone with Zigbee Solution
8th December, 2004
ASIA : Pantech&Curitel features world first Zigbee phone at
Zigbee Alliance Festival held at Marriott Hotel today. Zigbee is
one of the wireless data transmission solutions with home
networking automation function. Korea’s Korwin and Orange Logic
share its credit in the development – home networking and
location based services(LBS) respectively. Simply speaking, a
mobile phone meets cost-effective ubiquitous technology.
The festival is hosted by Zigbee Alliance, an association of
companies working together toward future Zigbee products on
global standard. At the ceremony, Pantech&Curitel exhibits the
world’s first Zigbee-applied mobile phone. The model P1 was
available without Zigbee solution at the market from last
September. Yet this ubiquitous phone at its test stage would not
be immediately available for sale. According to Mi-Hyang Han, a
person in charge at Pantech&Curitel, “The worldwide IT industry
is progressing toward wireless ubiquitous environments. A mobile
phone, becoming more like a commodity, is likely to be a hub of
upcoming ubiquitous era.”
Zigbee technology, for example, makes it possible to control the
home network. At the festival, the Zigbee-applied P1 of Pantech&Curitel
will demonstrate intellectual home/building networking service
such as controlling electrical appliances, alarming mail
receiving, checking temperature and humidity, sending mobile
messages to alarm in case of trespass. Moreover, with LBS the
Zigbee phone can guide more precise information on the route
than exiting GPS function. For instance, it provides you with
the names of restaurant and even the menu or price of the chosen
restaurant without connecting wireless internet.
Pantech&Curitel has already launched its 13 models of mobile
banking phones, which are considered as the first stage of
ubiquitous. It latest model, PH-K1500 can recognize the scanned
letters by OCR(Optical Character Reader) with Bluetooth function.
In 2005, Pantech and Pantech&Curitel are planning to launch more
handsets with Bluetooth, IrDA(Infrared Data Association), Zigbee
and DMB mobile phones.
About WPAN(Wireless Personal Area Network) technology
WPAN technology can be classified into three big categories-
IrDA, Bluetooth and Zigbee. IrDA transfers data in a very short
distance with higher speed and security. Bluetooth and Zigbee
carry out bigger data in a broader range of area. Especially,
those two technologies are expected to lead future ubiquitous
markets.
IrDA Bluetooth Zigbee
Frequency (using infrared light) 2.4GHz 2.4GHz, 868MHz, 915MHz
Transmission Distance 1m 10~100m 30m
Main Function Faster Data transmission Voice transmission Sensor
Control/ Data Control
Both Pantech and Pantech&Curitel already developed the mobile
phones with WPAN technology. They are now expected to lead the
future ubiquitous markets with leading-edge technology.
About Pantech&Curitel
Pantech&Curitel (President & CEO, Moon-Seob, Song) is one of the
BIG3 handset manufacturers in Korea. Since 1983, Pantech&Curitel
has been designing and manufacturing mobile phones for global
market. Leading the world of wireless technology, Pantech&Curitel
capitalize its years of experience and technology in ever
increasing market share.
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