How wireless commissioning is performed in a smart home: Part 1

Article By : Asem Elshimi, Silicon Labs

You must think of unboxing, configuring, connecting and provisioning when carrying out wireless commissioning in a smart home device.

Commissioning is among the first few steps in an IoT device’s lifecycle; it’s done in the first few minutes you spend with your newly bought smart home device. The first step is unboxing the device, and the second is pairing it with your home network. This pairing step is often kept very simple from the consumer standpoint.

The worst user experience would be a complicated pairing device. No consumer wants to read catalogs or dig deep into the technical aspects of pairing the smart home product. All they want is to open the box, push a button or two, swipe twice or thrice, and make the device function.

Figure 1 Smart home consumers expect a simple commissioning process. Source: Silicon Labs

But what actually happens throughout the pairing process carries a significant weight for the reliability of the device lifecycle. Pairing involves configuring the wireless device to its environment—for parameters like adjusting power levels and synchronization—and provisioning the device.

Provisioning or authentication is the process of attesting the device identity. Provisioning is instrumental in protecting users against counterfeited devices—not to mention that every network must have a solid provisioning protocol to protect itself against intruders and hackers that might try to pair with the network in order to gain access to sensitive information.

Therefore, when you think of commissioning, you have to think of unboxing, configuring, connecting and provisioning. These four steps should be done securely, seamlessly, and quickly. However, consumers look for a simple and intuitive process. So, what are the technologies available today to perform wireless commissioning and how do they work?

The most intuitive commissioning technology available today is near-field communication (NFC).

Provisioning with NFC

One of my engineering heroes would always say that “You can do so much with just the basics.” His wisdom applies to how NFC uses a simple induction mechanism to “scan” a device identity. When an NFC reader comes close to an NFC tag, the inductors on both devices form a mutual induction channel on which an exchange of information takes place (Figure 2).

Figure 2 NFC is the most commonly available technology for wireless commissioning in smart home. Source: Silicon Labs

The identity of an NFC tag can be confirmed by swiping past it with an NFC reader. For a smart home consumer, this would mean swiping the newly bought light bulb by the phone to attest its identity. Things don’t get more intuitive than that. Humans like the affirming sensation they get from swiping objects as commonly seen in the credit card transactions.

As intuitive as it is, NFC provisioning comes with a downside: added cost and footprint. NFC circuits don’t consume a whole lot of area and are relatively cheap components. However, NFC circuits are supposed to be used only once throughout the entire device lifecycle and for one mission only: to provision the device. So even with a cost as low as 10 cents, NFC circuits prove to be a burden that OEMs usually don’t want to absorb.

Another downside is NFC’s limited functionality. Commissioning is a multi-step operation and an NFC can handle provisioning well; however, that doesn’t include configuring and connecting the device to the network. NFC tags are passive data storages which can be read, and under some circumstances written to, by an NFC device. They typically contain small amounts of data—thousands of bytes—and are read-only in normal use. Not much else can be achieved with such a small amount of data.

Moreover, NFC tags don’t scale very well with larger node counts. This might not be too much of a problem in the smart home scenario, but more so a challenge in the smart building environments where installers look at commissioning thousands of nodes all at once. Swiping every node with a smartphone might take a couple of days. It would also make a big difference to commission smart home products that are placed in difficult to reach places, such as a maintenance sensor network attached to an air conditioning unit. Users would be excited to see a way to commission such nodes remotely and securely.

Figure 3 Several wireless technologies offer remote commissioning features for smart home settings. Source: Silicon Labs

Remote commissioning technologies

Is there, then, a technology that is remote, scalable and doesn’t add extra cost? While remote commissioning is still in its early phases, there are actually a range of technologies that exist and are in development phase. That includes Bluetooth authentication and pairing, Z-wave smart start, and Zigbee Direct. The common thread between the three is that they enable users to commission devices remotely at no added cost, as they all use the same underlying radio technology to commission their end devices.

So, smart device manufacturers can avoid the integration of additional radios or circuits just to enable remote commissioning. Remote commissioning technologies can also enable continuous attestation of devices in use. Because provisioning is done remotely, it can be repeated during device lifecycle to confirm its identity and check on its health. Last but not least, remote commissioning makes scalability possible. With remote commissioning technologies, there is a potential future where commissioning thousands of nodes takes no time or effort.

Figure 4 Zigbee Direct, a feature currently under development, allows users to seamlessly interact with their Zigbee networks using smartphones, tablets, and other Bluetooth-enabled devices. That, in turn, simplifies and streamlines the commissioning process. Source: Silicon Labs

So, what do these technologies offer? Let’s explore one of the most widely used connectivity mechanisms: Bluetooth. The most basic form of Bluetooth pairing is called Just Works, which offers the simplest path for pairing two Bluetooth devices. However, it does not offer a way of verifying the devices becoming part of the connection and making the network vulnerable to attack.

For instance, the man-in-the middle attacks occur when a third device—the malicious device—impersonates one or both of the two legitimate devices. Here, the malicious device routes the communication between the two other devices, giving the legitimate devices the illusion that they are directly connected to each other when their connection has been compromised. This setup not only allows the malicious device to intercept all the data being sent, but also allows it to inject false data into the communication or remove data before it reaches its intended recipient.

To counteract this threat, numeric comparison pairing can be used to improve Just Works, but it adds another step at the end, defeating the purpose of an easy Bluetooth pairing. The market needs an automatic and simple process for remote commissioning, but unfortunately, we are not there yet. We don’t see a protocol that streamlines commissioning and brings it to a zero-touch experience. However, we are close to solving this problem. With the right vision, the developments happening today will get us to the holy grail of wireless commissioning.

This article was originally published on EDN.

Asem Elshimi is product marketing manager at Silicon Labs.


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