Understanding Home Automation Standards
Affordable home control capabilities have brought big changes to the security industry by making systems easier to sell and boosting upfront and recurring revenue. Dealers are earning about $14 per month in smart home revenues according to January 2016 research from Parks Associates. Seven in 10 dealers surveyed said they currently offer some type of smart home device or system or intend to do so within the next 12 months.
Enabling the burgeoning home control market are a range of wireless communications standards that give security systems the ability to control thermostats, video cameras, door locks and other devices. Today these standards include Z-Wave, ZigBee, Bluetooth and Wi-Fi. Manufacturers build communications capability into their products based on which option they believe is best suited to the task at hand.
It’s a good idea for dealers to understand the basics of how the various communications technologies work. Dealers also will want to know about some additional options that are under development, including new versions of the Wi-Fi and Bluetooth standards, as well as a new standard known as Thread.
Tasks Drive Different Requirements
Different elements of a home control system have different communications needs. Video, for example, needs high bandwidth — and when high bandwidth is needed, manufacturers generally use Wi-Fi communications. Wi-Fi is costlier to build than other communications technologies, however, and most other home control options don’t need Wi-Fi’s bandwidth.
“In general, when it comes to control and automation there’s a relatively small payload,” explains Dave Pedigo, senior director of learning and emerging technologies for the Custom Electronic Design & Installation Association (CEDIA), Indianapolis.
For most applications the bandwidth requirements are in the kilobits per second, Pedigo notes. In comparison, video bandwidth requirements can be in the megabits per second.
The Z-Wave and ZigBee standards both were designed for low-bandwidth home control applications. A critical requirement for home control is long battery life; both technologies were designed with that usage in mind. A typical smart home device can run for several years between battery changes, sources say.
Both technologies also provide a range of about 50 feet. That range can be multiplied, however, by the mesh capability built into both technologies. Mesh technology lets devices in a network act as repeaters for other network devices. “There’s not much of a range issue as long as some devices are in range with the others,” Pedigo explains.
Bluetooth technology originally was developed for applications such as headphones and printers that have high bandwidth requirements but don’t need the range or battery life of home control standards. More recently, however, a new version of the standard was developed for home control and other Internet of Things (IoT) applications. The standard, officially known as “Bluetooth with low-energy functionality” or “Bluetooth 4.0” is often referred to simply as BLE.
In comparison with the original Bluetooth standard, BLE offers less bandwidth but greater range and battery life. Currently BLE does not have mesh capability, but products supporting a new version of the standard that includes mesh capability are expected to be on the market by mid-2016, according to Steve Hegendorfer, director of developer programs for the Bluetooth Special Interest Group (SIG), which is responsible for Bluetooth standards.
A key differentiator for Bluetooth is that the technology is built into today’s smartphones — and manufacturers of home control devices are beginning to build Bluetooth into those devices so that homeowners, for example, can unlock a door or turn on a light using their smartphones.
Who Defines the Standards?
Ask stakeholders about the differences between standards such as ZigBee and Z-Wave and the conversation will quickly turn to the topic of who defines the standards.
“ZigBee is a true alliance,” comments Mark Walters, vice president of strategic development for the Davis, Calif.-based ZigBee Alliance, which is responsible for ZigBee specifications. “We write standards, put them in the marketplace and back away.”
The ZigBee chips that manufacturers build into their products are available from multiple manufacturers, Walters says. That means “the standard has to be written tight enough that two manufacturers can follow it and their devices will work together.”
The situation is a bit different with Z-Wave. Detractors may tell you that Z-Wave chips are only available from a single chip manufacturer, Sigma Designs — although Mitchell Klein, executive director for the Z-Wave Alliance, notes that a second source is now available.
Members of the Z-Wave Alliance do have influence over specifications, Klein says about the Fremont, Calif.-based alliance. He adds, though, that Z-Wave is not designed by committee with the net advantage that new releases can be rapidly implemented.
Another advantage of Z-Wave over ZigBee is that there is a single specification for popular applications such as door locks or thermostats, and new versions are designed to be backwards-compatible, Klein says.
Walters acknowledges that in the past ZigBee had multiple ecosystems. For example, there was a lighting system ecosystem that was separate from the home control ecosystem and light controls designed for the lighting system ecosystem were designed to a different specification than light controls designed for the home control ecosystem. Recently, however, ZigBee adopted a new approach called ZigBee 3.0 that establishes a single specification for key applications, Walters notes.
According to Walters, Bluetooth has no specifications at all for some applications at this point in time. Hegenderfer addresses that concern. “We have our own application framework for generic attributes, or GAT,” he explains. That framework determines how to describe applications such as motion detectors and includes model use cases. Developers can model use cases with GAT, he notes.
As an alternative to the application libraries that ZigBee and Z-Wave have, Bluetooth offers something similar called adopted profiles, Hegenderfer adds. This approach, he says, makes it easier for developers to create products that are interoperable with other Bluetooth devices but that also include the developer’s own “special sauce to do something special.”
Products supporting yet another communications standard are about to hit the home control market.
The new standard is known as Thread and according to Skip Ashton, vice president of technology for San Ramon, Calif.-based Thread Group, the standard uses Internet protocol (IP) for communications and is designed to make home control devices look like Internet-connected devices.
Prior to Thread, Ashton says, IP connectivity hasn’t been available on low-power, low-memory, low-cost devices.
Another key goal for Thread was to address security issues with IoT devices, Ashton says. If home control devices are designed for communications outside the home, as many of them are, today they require a gateway to translate IP communications from the smartphone or computer that is remotely controlling the system. According to Ashton, those gateways may be vulnerable to security breaches, particularly considering that they may not receive frequent software updates.
Thread is designed to support mesh connectivity. It will operate in the same 2.4 GHz spectrum band that is used by ZigBee and Wi-Fi devices and it will use the same 802.15.4 protocol that defines the wireless connection underlying the ZigBee protocol, which means it will have equivalent range, bandwidth and battery life. (Z-Wave uses the 900 MHz spectrum band, which, according to Klein, is less prone to interference because few other devices use that band.)
Walters raises the same argument against Thread that he did against Bluetooth. “They haven’t standardized the applications layer,” he argues. “There is no specification for a door lock that multiple manufacturers can build to.”
Ashton, however, says that ZigBee applications can be adapted to run over Thread.
Meanwhile, the Bluetooth SIG is hoping to finalize the specification for an update to the BLE standard.
According to Hegendorfer, the updated version will double the bandwidth and extend the range that the standard can support. Once the standard is finalized, products supporting the offering could be on the market in as little as six months, Hegendorfer says.
A new version of Wi-Fi that should be of interest to the home control market is also in the works, notes Pedigo. A joint effort of the IEEE and the Wi-Fi Alliance, the 802.11ah standard will add mesh capability, he explains.
Perhaps it’s not surprising that so many home control standards have emerged, considering that home control is one aspect of the Internet of Things— and industry analysts are forecasting huge IoT growth. The good news is that with so many resources focused on this area, the home control market should see significant innovation and economies of scale.
The task of keeping up with home control standards could become even more daunting when two additional emerging standards become reality.
The AllSeen Alliance is responsible for AllJoyn technology. According to the AllSeen website, the organization is “a cross-industry consortium dedicated to enabling the interoperability of billions of devices, services and apps that comprise the Internet of Things.” Key members include Qualcomm, Microsoft and other industry heavyweights.
The Open Interconnect Consortium (OIC) touts highly similar goals on its website, where it says that the organization is “being founded by leading technology companies with the goal of defining the connectivity requirements and ensuring interoperability of the billions of devices that will make up the emerging Internet of Things (IoT).” This group also has assembled a wide range of backers including Cisco, Intel and others.
One aspect of home control communications standards that can be confusing is when standards organizations start talking about different layers of the protocol stack. The ZigBee Alliance offers a useful diagram that helps explain the three layers of the ZigBee 3.0 standard and their functions. Similar concepts also apply to other home control standards.
Some readers may be familiar with the OSI Model that has been critical to traditional IT networks for decades. That model has seven layers that define the various tasks that the networks have to perform — and traditional IT standards such as Wi-Fi are based on that model.
Home control standards are based on simpler models. The ZigBee standard, for example, compresses the lower two layers of the OSI Model into a single layer defining wireless connectivity aspects of the technology. That portion of the ZigBee standard is the 802.15.4 standard.
The middle four layers of the OSI Model in ZigBee are compressed into a single layer that defines networking functionality — how a device connects with other devices. Like the OSI Model, ZigBee also has an application layer at the top. An example of a home control application would be a door lock or a thermostat.
For more on automation standards, visit SDM’s website where you’ll find the following articles.