Easy VRF & DSS Integration Solutions for BACnet, Modbus, Wifi
EMAIL INTERVIEW Mark Walters & Ken Sinclair
Mark Walters, Chairman, Z-Wave Alliance
Mark Walters is the Chairman for the Z-Wave Alliance, a leading provider of wireless networking technology for control and status reading applications and the developer of Z-Wave. Mark joined Zensys in July 2006 and brings extensive experience in home automation and control including residential structured wiring, automated lightning and controls, security, distributed audio and entertainment solutions.
Mark is responsible for the day-to-day management of all activities for the Z-Wave Alliance, a consortium of more than 125 leading companies in the home technology space dedicated to solidifying Z-Wave as the standard for wireless home and entertainment control products. Markís responsibilities include the development of programs to grow the membership of the Z-Wave Alliance and provide value for all members, such as Z-Wave Developer Forums, Un-Plug Fests and applications training.
RF Interference Problems
In short, there can be RF interference in any band. Some bands are more crowded than others, and some applications are more susceptible than others.
Sinclair: I read a recent white paper you published on interference problems with ZigBee and WiFi. The ZigBee Alliance claims there are products addressing both and there is no interference since they are IEEE standards. What is your position?
Walters: Obviously there are applications that are not going to suffer from interference problems. At the same time, you donít have to look very hard to find examples of companies abandoning 802.15.4 in certain application spaces due to clearly demonstrable interference issues from other 802 technologies.
Many of the companies using Z-Wave technology in the home control space today initially began working with ZigBee and 802.15.4 radios. They eventually realized that in addition to the lack of consumer level interoperability and the drawn-out time to market that's characteristic of large committee-based standards development, that they were going to face more and more coexistence issues with high duty cycle use of other 802 technologies, such as WLAN and Bluetooth. This is particularly true in environments where these technologies will be used for video streaming.
Two 802 radios can coexist in the same product as long as the product doesn't have both radios operating at a high duty cycle at the same time. You can clearly see from independent studies that duty cycle, power level and proximity of the devices all factor into the level of degradation of performance. Simulations that have been run by the 802.15 group and published in their documents clearly indicate this observed interference and degradation in performance.
In short, there can be RF interference in any band. Some bands are more crowded than others, and some applications are more susceptible than others. In a typical residential environment, the prevalence of WLAN and the inevitability of 802.11n as a popular high duty cycle transport for audio and video signals suggests this not a good band for home control applications.
Sinclair: I have also heard that Z-Wave has its own interference problems. Is there any truth to that?
Walters: I have not heard of any reports of RF interference problems in a Z-Wave network. Z-Wave operates in the license-exempt 900MHz ISM band, at a very specific narrow frequency. Our data packets are small and typical applications use very little time or duty cycle to transmit. In the event that there is a local interferer, unless it's operating on exactly our frequency and transmitting at close to full duty cycle, we are not going to experience any meaningful degradation in performance. The 900MHz band is not nearly as busy as the 2.4GHz band and the applications found on the 900MHz band tend to use much lower power and duty cycle than WLAN or Bluetooth applications. A good analogy for the multi-channel 2.4 GHz radios would be riding a bicycle on a multi-lane freeway. Would you feel safer riding in the unused lanes or within the dashed lines that are used to separate each lane? The corresponding analogy for Z-Wave would be that we are riding on a bike path next to the freeway. Some might claim that we share this path with an occasional scooter, but personally, Iíd take the bike path.
Sinclair: One of the big knocks against Z-Wave has been that it's a proprietary technology and therefore doesn't have the ability to scale. What is your response to that statement?
Walters: Letís review the reality of what is open to the consumer and in which technology developer an OEM finds more partners with products to cooperate with Ė and where we see more growth in available, interoperable products.
Z-Wave has more cross-manufacturer, cross-application, interoperable products than any other control technology in the residential and light commercial space. These are real products, available on the shelf today, from end product manufacturers that are leaders in their product categories. These include successful, highly established consumer product companies such as Leviton Manufacturing, Monster Cable, Logitech, Intermatic and Wayne Dalton.
Iím not sure what you mean by scaling, but lets look at some of other ďproprietaryĒ non-international standards, technologies such as CD, DVD, Dolby and HDMI. Obviously, these have achieved scale in the market. If anyone has forgotten, Ethernet started as a proprietary technology developed by the Xerox PARC lab.
Last month Zensys introduced a licensing program for the Z-Wave technology as a next step of opening the technology to other chip suppliers.
Sinclair: How many Z-Wave products are there on the market?
Walters: As of June 1, 2007 there are over 150 Z-Wave products available in the US market and around 25 in the European market. There are another 45 or so that are scheduled to go through the certification process in the next 4 to 6 weeks. We will see a doubling of the available products in the US market and at least a three fold increase in the European market by the end of 2007.
Sinclair: What is the certification process like for Z-Wave? Is this a big differentiator?
Walters: Z-Wave certification means one thing to the consumer Ė the guarantee that products will work better together. We donít have different revisions of Z-Wave that arenít interoperable; we donít have different physical layers of 900MHz and 2.4GHz that arenít interoperable. We donít certify just the protocol layer and we donít certify just the physical layer. We certify interoperability that goes from product to product and application to application. That's what is important to the consumer.
All Z-Wave certified products use the same physical layer, the same protocol layer and most importantly, the same standardized device command sets or profiles. Z-Wave products are certified by third-party independent test labs, to align with standards that are created by and ratified by the OEM companies that manufacture the products. The Z-Wave Alliance, a consortium of over 160 companies, maintains a suite of software compliance test tools that complement the ratified written standards and are used to streamline product development. The Alliance also holds regular Un-Plug Fest events, where production level products are tested in real world applications for interoperability and overall end-user experience. These actions and initiatives ensure interoperability and a good consumer experience.
Sinclair: Where do you see Z-Wave's most important opportunities and growth areas for the future?
Walters: Z-Wave's initial successes have come from applications like remote controls, lighting control and HVAC, this last one is particularly prevalent in Europe. By its nature, Z-Wave lends itself exceptionally well to a wide variety of additional applications, such as home security, access control, motorized window treatments and appliance control. We're also deeply involved in new applications for energy conservation and telemedicine, which we believe will be important new markets in the very near future. While future applications are interesting to contemplate, it's important to stress that Z-Wave is already an established force in today's applications. We have real products that are shipping today.
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