Why Matter Is Vital for the Smart Home

Steven Keeping for Mouser Electronics

Matter promises to see the smart home finally realize its potential. (Source: AndSus - stock.adobe.com)

Connected houses and appliances simplify life for householders—making it easy to order groceries, check the sports results, or summon a little acoustic chill—and offer part of the answer to some more serious challenges. For example, a smart electric vehicle (EV) charger for the home can determine when renewable energy is available to replenish batteries, or a smart washing machine can decide on the exact amount of water to use based on the weight of clothes in the drum and how soiled they are, thus minimizing the use of finite resources.

Unfortunately, complexity is stalling smart home product adoption. Today, even tech-savvy buyers struggle to get their smart-home products working in harmony. For example, early adopters may find a digital voice assistant from one manufacturer struggle when trying to configure and control smart lights or an air-conditioning system built by another vendor. Even with a smart-home ecosystem from a reputable supplier such as Apple, Amazon, or Google, consumers seem to be forever fiddling to keep equipment connected. It seems the realization of the fully integrated smart home is still some way off.   

The kernel of the problem is the lack of interoperability between wireless technologies, even between those based on standards. Today, there are approximately 14 different wireless and wired connectivity technologies targeting the smart home sector, and almost none of them communicate with each other. Consolidation is afoot, with Bluetooth® Low Energy, Thread, Wi-Fi®, and Zigbee taking a large share of the market due to big vendor ecosystems and the backing of major smart home end-product makers. But consolidation will not solve the problem because even these popular alternatives don’t work together.  

Introduction of Matter

Introducing yet another standard hardly seemed to be the way to finally achieve a fully interconnected smart home. Realizing that no single wireless connectivity standard is ever likely to emerge, more than 200 companies in the tech industry came together as the Connectivity Standards Alliance (CSA) with the aim to resolve interoperability and incompatibility issues with wired and wireless technologies. Drawing upon the expertise and innovation of CSA’s member organizations—which include tech giants Apple, Google, and Amazon; large and small device manufacturers such as Eve Systems, Yale Home, LEEDARSON, Netatmo, and Tridonic; and major wireless chip vendors—CSA introduced the Matter standards-based protocol.

Matter is not designed to compete with the established smart home technologies, but rather to enable popular standards-based protocols such as Bluetooth Low Energy, Thread, and Wi-Fi to operate together. The CSA describes Matter as a protocol to connect compatible devices and systems with one another, bringing secure, reliable, and seamless connectivity to smart-home devices.

For consumers, Matter promises to make things much easier. Instead of researching if a thermostat is Apple compatible or if an Amazon Echo device can control a Yale smart lock, buyers can look for the Matter certification mark on devices for assurance that all the products will work nicely together (Figure 1).

 
Figure 1: A selection of smart home end-products targeted by Matter at its launch. (Source: Connectivity Standards Alliance)

The Matter initiative also makes it easier to enforce a baseline of standardized security expectations—increasingly important as more personal data is shared between products from different manufacturers. The CSA says Matter’s security is supported by a proactive community of members that perform activities such as threat modeling and mitigation. The alliance has also committed to respecting consumers’ data and ensuring any data shared is restricted to supporting device operation. Privacy is further enhanced because Matter allows devices to interact and operate without needing to send data to the cloud.

Because more than 200 companies participated in its development, Matter has widespread backing. Does this backing guarantee Matter’s success? It will certainly help, but beyond these positive commercial foundations, some well-thought-out technical underpinnings should see Matter thrive. Here we take a closer look at the Matter standard’s engineering advantages.

Smart Home Connectivity Choices

There is no single, dominant short-range wireless protocol for the smart home because different applications demand different trade-offs. For example, one application might trade range for throughput, while power consumption might be the most important operational factor for another. Other influences on the choice of wireless protocol include interference immunity from other radio sources operating on the same frequency, mesh networking capability, and Internet Protocol (IP) interoperability. (IP is essentially a network layer communication standard for rapidly moving data across the internet. Every supported device has its own IP address and can easily connect to the internet without an intermediate device). The Matter standard allows for flexibility in the choice of wireless technology by initially being launched to support wired Ethernet installations, plus Thread and Wi-Fi. Bluetooth Low Energy is used for commissioning new devices to the smart home network.

The CSA carefully appraised the wireless and wired technologies selected for Matter, basing the choices on the following reasons:

• Wi-Fi is a familiar, globally established technology that offers high throughput.
• Thread is a low-power wireless standard that seamlessly integrates with larger IP networks without the need for a gateway.
• Bluetooth Low Energy is interoperable with smartphones, which can be used as a user interface to smart-home devices.
• Ethernet is typically used to connect a Wi-Fi access point (AP) to the internet.

Wi-Fi for Throughput
Wi-Fi is a logical choice for smart home connectivity because of its ubiquity and familiarity. Like Thread, it includes native IP support ensuring connectivity to the cloud through the home AP. The latest standard, Wi-Fi 6, includes capabilities that make it even better suited for smart-home applications. For example, the Wi-Fi 6 standard includes features that reduce power consumption and others that enable many more devices to seamlessly share the available bandwidth without extended latency. These features do not come at any cost to Wi-Fi’s high throughput, enabling Wi-Fi 6 to support higher-bandwidth smart-home applications such as smart speakers and entry cameras.   

Thread for Power Saving
Matter supports Thread because it is a secure wireless mesh network technology specifically developed for the smart home by the Thread Group—which includes Google, a founding member of the CSA. As a result, it is designed for efficiency, reliability, and low latency. Thread is suited to low-power, low-bandwidth devices such as sensors, door locks, smart lights, and thermostats—the so-called Sleepy End Devices (SEDs) in the Thread specification (Figure 2).

 
Figure 2: The Thread stack adds an IP interoperable network layer to the IEEE 802.15.4 physical (PHY) and medium access control (MAC) layer. (Source: Nordic Semiconductor)

Thread is an IPv6 standards-based mesh networking protocol. That makes it simple for Thread smart-home products to join any larger IP networks—such as those powered by Wi-Fi or Ethernet—without the need for proprietary gateways, although connection does require a Thread Border Router. Smart-home device manufacturers such as Apple and Google are building these border routers into their products. Because of guaranteed interoperability, a Thread device from any manufacturer will work with a Thread Border Router from any other.

Bluetooth Low Energy for Commissioning
Bluetooth Low Energy shares many attributes with Thread, including low power consumption, network support, and familiarity. However, it lacks Thread’s IP interoperability, instead being primarily designed to leverage smartphones or other gateways to connect to the cloud. And this smartphone interoperability is a key reason why the Matter standard supports Bluetooth Low Energy. It means consumers can wirelessly connect with their smart-home devices through their smartphones and then use them to commission and configure smart-home products.

How Does Matter Work?

The Matter protocol is built on a common application layer and data model that delivers interoperability between devices, allowing them to communicate with each other across multiple IP network technologies.

Closer inspection reveals that Matter forms the Application, Presentation, and Session OSI/ISO stack layers of a larger protocol software stack. The larger software stack employs a Transmission Control Protocol/User Datagram Protocol (TCP/UDP) transport layer and an IPv6 network stack, which could also be supported by Wi-Fi and Thread protocols. Ethernet, Wi-Fi, and IEEE 802.15.4—plus Bluetooth Low Energy—form the datalink and PHY layers (Figure 3).  

 
Figure 3: The Matter stack forms the Application, Presentation, and Session layers of a full OSI/ISO stack. (Source: Nordic Semiconductor)

Now that we have covered the technical details, what does Matter do in the everyday smart home? Let’s break down the answer by looking at the Thread network first. The CSA envisages most smart home devices—for example, smart lights, window shade controllers, smart locks, and smoke detectors—will form a Thread network. That allows them to speak to each other and, crucially, use the services of another Thread device to route information to a further Thread device on the network and/or a Thread Border Router. So, for example, a single switch could be used to operate both a light and a window shade, or a smart lock could receive an incoming message from a remote homeowner via a Thread Border Router and then forwarded by a smoke detector, allow a maintenance worker into the house. The Thread network overcomes the range limitations of a single device and prevents the failure of any device causing the entire network to fail.

At the edge of the Thread network lies one or more Thread Border Routers. It is envisaged that most smart-home Thread networks will feature multiple border routers, again ensuring the failure of one device doesn’t compromise the connection to other networks. The border router forms a bridge from the Thread network to Wi-Fi or Ethernet and, from there, to the cloud.

Because Matter supports Thread, the border router is a relatively simple and inexpensive device compared to the gateways or hubs used by other wireless protocols to bridge to the internet. And the border router connection to the internet via the Wi-Fi router enables a remote user to access any of the devices from an app on a smartphone or tablet (Figure 4).

 
Figure 4: The Thread mesh network uses border routers to connect to Wi-Fi and from there to the internet. (Source: Thread Group)

While it’s possible for Thread to connect to Wi-Fi without the Matter Application layer, the link can be clunky to set up and can lack reliability. Matter makes things simple for Thread devices to robustly communicate with the home Wi-Fi network and from there to the cloud.

Wi-Fi devices with Matter support connect to an AP and, from there, to the internet or to a Thread mesh network via border routers. As these Wi-Fi devices will typically use Wi-Fi 6, which has improved range compared to previous versions, there is little need for them to support mesh networking to cover the entire house. That, in turn, enables the devices to be compact and use less power.

The final element of the Matter ecosystem is a Matter controller. Controllers are incorporated into products such as smartphones, tablets, and PCs. The controller forms a node in the Matter network and is used to remotely commission and control any Matter device. Bluetooth Low Energy is used during the commissioning process to securely transmit the network credentials and provision the Matter device into the Thread network. After commissioning, the device uses IPv6-based communication (i.e., Thread or Wi-Fi) to interact with other network devices (Figure 5).

 
Figure 5: The Matter controller uses Bluetooth Low Energy for commissioning; thereafter, communication between the controller and the Matter device is by IPv6 communication. (Source: Nordic Semiconductor)  

Matter controllers can also be used to bridge to other networks that are outside the Matter ecosystem—for example, a Zigbee network (Figure 6).

 
Figure 6: Matter supports seamless connectivity between Thread, Wi-Fi, and the internet. Matter controllers commission and control the Matter devices and bridge to non-Matter networks. (Source: Nordic Semiconductor)  

Matter’s interoperability enables a connected product to be simultaneously controlled by two different smart-home systems, which the Matter standard refers to as “fabrics.” For example, a smart light bulb could be switched on by a smart speaker from one supplier or through a Matter light switch controlled by another maker’s tablet. A Matter device can join multiple fabrics, and each fabric has its own Matter controller unrelated to other fabrics through which the Matter device might be commanded. Each fabric operates independently.

Getting Started with Matter

Matter was originally announced in 2019 as Project Connected Home over IP (CHIP). Following an August 2021 rebrand to Matter, version 1.0 of the standard was adopted in October 2022, and with it, the Matter certification program was launched.

Today it’s possible to purchase Matter chips from a selection of silicon vendors. In addition, Matter certification labs are up and running worldwide, and companies are submitting their smart-home devices for Matter certification.

For Matter prototyping work, Matter chip providers typically provide a Matter software development kit (SDK) supported by several mainstream integrated development environments (IDEs). For a full Matter solution, the SDK must support both Matter-over-Thread and Matter-over-Wi-Fi. Manufacturer SDKs often include application examples such as a Matter switch controlling a smart light.

For prototype work, the Matter controller could be a Linux PC with a CHIP tool or similar arrangement. The PC and CHIP tools enable the commission of Matter devices onto the network and communication with them using Matter messages. The Thread Border Router could be constructed from a low-cost computer, such as a Raspberry Pi 4, running an open-source Thread stack like OpenThread.

In Figure 7, the Matter switch doesn’t know which Matter light bulb to control. The switch must be linked to the bulb through “Matter binding,” a process through which the Matter controller configures the Matter switch to control a specific Matter light bulb.

 
Figure 7: Matter binding is used to associate a Matter switch with a specific smart light bulb. (Source: Nordic Semiconductor)

Conclusion

Lack of interoperability is stalling widespread adoption of smart-home devices. Products designed for one manufacturer’s ecosystem do not play nicely with those from another—making it complicated for consumers to get their connected home up and running. The Matter protocol offers a solution. Based on IPv6 standard technologies such as Ethernet, Thread, and Wi-Fi, Matter not only promises seamless connectivity between smart-home products from different vendors, but it also allows developers to focus less effort on interoperability patches and workarounds and place more effort into innovative, secure, and robust solutions. In just a few years, the smart home will be able to minimize its energy consumption, keep everything secure while the owners are away, arrange for repairs to the broken roof tile that’s letting in the rain, and adjust the temperature and light to suit each occupant’s needs before they return home.  

Key Takeaways

• Multiple incompatible wireless standards are stalling adoption of the smart home.
• Products from different manufacturers and key smart-home ecosystems are complicated to set up and produce patchy results.
• The Matter standard adds a unifying application layer to IPv6-based wireless technologies, ensuring interoperability and seamless operation between Thread, Wi-Fi, Ethernet, and the internet.
• Getting started with Matter is made easier with chip makers’ SDKs.
• Matter promises to make smart-home products more secure and to protect users’ privacy.