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ZigBee Alliance V.P. Shares Thoughts on Interoperability, Competitors
By Will McNamara, Principal Consultant, KEMA
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I recently spoke with Brent Hodges, Vice President Marketing and Business Development of the ZigBee Alliance, as he made preparations to attend the DistribuTECH conference in Tampa. This was a good opportunity for Hodges to share new developments happening at the Alliance, and also to clarify what may be some misinformation that is circulating in the industry regarding the ZigBee technology.
For those who may be unfamiliar with the group, the ZigBee Alliance is a non-profit, volunteer organization of international members who are committed to developing global, open standards for communications products. The Alliance is essentially responsible for three things: 1) helping its members write specifications and creating the standards that are used; 2) creating the certification and compliance programs used by global product testing labs to provide approval for products that meet the standard; and 3) branding, marketing, and educating the industry about the ZigBee standard and the Alliance itself.
The ZigBee technology is intended for use in embedded applications requiring low-data rates and low-power consumption. According to the Alliance, the ZigBee specification defines inexpensive, easy-to-use, self-organizing and self-healing mesh network that can be used for energy management, industrial control, embedded sensing, building and home automation, etc. The resulting networks use very small amounts of power so individual devices can run for years using batteries. Some member companies have developed products that run in excess of 10 years on batteries for applications such as gas meters.
The ZigBee specification provides the network, security, application-framework, and application-profile layer overlay on top of the IEEE 802.15.4 PHY (physical) radio standard and MAC (media access control) layers. ZigBee is supported by a large group of worldwide product manufacturers and semiconductor companies. Put simply, ZigBee is the umbrella term for open standards-based, multi-manufacturer products that are guaranteed to operate with each other.
ZigBee operates in unlicensed bands worldwide at 2.4 GHz (global, with 16 channels), 915 MHz (Americas, with 10 channels) and 868 MHz (Europe, 1 channel). Transmission distances range from ten to hundreds of meters, depending on power output and environmental characteristics. To summarize, ZigBee products operate in the 2.4 GHz unlicensed industrial, scientific, and medical (ISM) band, though the technology works in the sub 1 GHz country specific bands as well.
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New Developments Signal Year of Growth
Hodges was very upbeat about the Alliance’s activities as it begins the new year. A number of its member companies have made some significant public announcements recently that Hodges was happy to highlight. “We are very excited about where ZigBee is today due to what our members are doing,” Hodges said. “We presently have about 250 members in the Alliance and there have been something in the order of about 20,000 development and evaluation kits shipped worldwide by Alliance members. These kits will be used by companies to find new ways in which the ZigBee standard ways to connect devices that were never connected before.”
Hodges also pointed to recent announcements at two member companies to demonstrate how ZigBee is being used at a growing number of utility AMI / Smart Grid deployments. In December, Itron announced that Southern California Edison (SCE) (both Itron and SCE are Alliance members), will deploy the OpenWay by Itron meter and communications system as part of SCE’s Edison SmartConnect metering program. OpenWay, which includes a ZigBee chip, is a standards-based, open-architecture smart metering solution that features two-way wireless communication to state-of-the-art electricity meters at homes and small businesses. OpenWay is designed to meet a broad set of customer energy management requirements—such as real-time energy communication to thermostats, information displays, and energy smart appliances - all using ZigBee technology. SCE appears to be on track to start SmartConnect deployment in the summer of 2008 , and OpenWay, with the ZigBee chip in every meter, is a key component of that deployment.
Also announced in December, Comverge (another Alliance member) has successfully launched the nation's first ZigBee-enabled demand response program as part of a pilot sponsored by the Center for the Commercialization of Electric Technologies (CCET). Using ZigBee-enabled demand response thermostats (SuperStat) and digital control units (DCUs), Comverge successfully executed load control operations from its hosted data center in Atlanta, Georgia, to selected residents in Houston, Texas. The CCET pilot is designed to integrate demand response systems with AMI technology.
The Houston pilot is being conducted across 500 homes within the service territory of CenterPoint Energy (an Alliance member) and includes retail electric provider participation from Reliant Energy and TXU Energy (also Alliance members) as well as Direct Energy. Itron is key player in this program as well. Itron OpenWay CENTRON® smart meters, currently being tested in a limited deployment by CenterPoint Energy, communicate with Comverge's SuperStats and DCUs to control central air conditioning systems and other high-usage residential appliances such as electric water heaters and pool pumps. During times of high electricity usage, Comverge demand response system can change thermostat settings by a few degrees or cycle off air conditioning systems for short periods of time by using the AMI system as a two-way communications infrastructure.
Another key development that Hodges alerted brought to my attention is that the ZigBee Alliance will soon be announcing the completion of the ZigBee Smart Energy profile. A press release is scheduled to go out on Jan. 22 that will outline the efforts of Alliance members. The ZigBee Smart Energy profile goes a further step to ensure that there is end-to-end interoperability between products built by multiple manufacturers. ZigBee Smart Energy was written by a number of Alliance members and is presently available to members only. A public version could be made available later this year.
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Setting the Record Straight
Hodges was also eager to set the record straight on a few mischaracterizations about ZigBee. Often in the press—perhaps too often, according to Hodges—ZigBee is mentioned in the same breath as Z-Wave, as if the two names represent a clear apples-to-apples comparison. Z-Wave, developed by Zensys A/S of Denmark, is a proprietary wireless RF-based communications technology designed for residential and light commercial control and status reading applications. Z-Wave operates at 868.42 MHz (E.U.) or 908.42 MHz (U.S.) and a data throughput of 9.6 Kbps. Z-Wave works in the ISM band on the single frequency using frequency-shift keying (FSK) radio.
Z-Wave is a proprietary product with Zensys as the single chip source and sole designer of the network protocol. Therefore, this is not an open standard that enables multiple suppliers and a major concern for companies who require standards-based solutions. One of the strengths of ZigBee is that it is based on the open-standard development work of its volunteer members. Secondly, it uses IEEE standards (802.15.4) to ensure global interoperability and ensure a robust supply chain. However, the fact that ZigBee is open-standards based and Z-Wave is a proprietary technology is not the only distinction between the two. For instance, Z-Wave is clearly targeted at home control applications. Those include not just traditional home control applications but also entertainment control and digital home healthcare devices. ZigBee and its members are addressing all of those markets and broadly addressing low-data rate and low-power device control.
Hodges says ZigBee and Z-Wave have very little in common and should not be viewed as competitors. “At the ZigBee Alliance, we do not compare ourselves against technologies from small companies,” Hodges said. “Those companies are out there making these comparisons. There are a number of proprietary technologies out there competing against each other and vying for airtime.”
Bluetooth is ultimately a better comparison to ZigBee than Z-Wave. Bluetooth, like ZigBee, is also an alliance of members seeking to establish open-standard based protocols. Both ZigBee and Bluetooth are based on IEEE.802.15 radio standards; both run in the 2.4 GHz unlicensed frequency and; and both use small form factors and low power consumption. Hodges says, “Bluetooth is a great technology for transferring files between devices like computers and phones at high data rates. By contrast, ZigBee targets low data rate devices like thermostats, light switches, electric meters that require a longer range with greater power efficiency, and the ability to network thousands of devices into a single network.”
Hodges was also eager to respond to some of the criticisms against ZigBee that have circulated in the industry. Z-Wave supporters have claimed that, because its products share a busy ISM band with Wi-Fi products, ZigBee is plagued with 2.4 GHz interference issues that do not exist in the 900 MHz band in which Z-Wave operates. Z-Wave has claimed that such interference issues do not exist in the 900 MHz region because there is no ubiquitous data communications technology at work there. Hodges says these claims are simply untrue. “The results of a thorough investigation were published in an Alliance white paper in June 2007. ZigBee was shown to operate reliably even in the heaviest of 2.4 GHz traffic. The ZigBee Alliance has seven out of 10 of the world’s largest semiconductor companies as members of the Alliance, and they wouldn’t be investing billions of dollars in ZigBee if the claims were true. ZigBee members actually build and sell products that use both ZigBee and Wi-Fi in the same box. The whole idea that ZigBee wouldn’t work around Wi-Fi is preposterous.”
One of the criticisms leveled against ZigBee is that it is not IP-enabled. Hodges contends the concern is really a non-issue. “ZigBee easily extends IP to devices,” Hodges said. “Putting IP on wireless sensor networks is overkill -- there is no reason that you would place so much overhead on a wireless sensor network. ZigBee provides common interfaces to IP. There is a lot of hype surrounding IP down to device level but other groups are not proposing to put IP on each device, but rather create a protocol that will proxy for the IP address. The ZigBee standard already does all of that.”
While the market potential for ZigBee is still unknown, many utilities remain very interested in the possible solutions that the technology can offer with regard to home area networks. Given the distinctions between them and the unique marketing approaches that are being taken, it would appear that the market at this point is large enough to sustain ZigBee, Z-Wave and Bluetooth, along with any other emerging competitors in the space. But it is clear that ZigBee is positioned for a strong year of growth in 2008. Despite the fact that the industry has yet to crown any of these competitors as the winning technology in the low-power mesh networking space, the ZigBee Alliance recently announced that its chipsets will see a change in annual growth of 111 percent, with chipset units reaching 120 million in 2011.
Contact the author at will.mcnamara@kema.com.
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Download the January 2008 Issue
Use the link below to download the PDF of the full issue of the January 2008 Automation Insight to view the complete print versions of the articles.
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[download] Automation Insight Jan 2008 (.pdf 334 kb)
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