If you’re interested in smart home technology you will probably have heard about the Matter standard, which aims to unify the smart home ecosystem with a common application layer for devices.
Matter-over-Thread is a key element of this, designed for connecting low-power, low-data-rate applications together in a mesh network. Coupled with Matter-over-Wifi for high-data-rate devices, you will soon be able to easily commission and control all of your devices seamlessly across platforms. (At least that’s the hope!)
In this article, I dive into what Thread is, and how it works. I explain how the various device types operate within the mesh and review how Thread compares with other mesh networks like Zigbee and Z-Wave.
What Is Thread?
Thread is a low-power, wireless IoT (Internet of Things) protocol designed to provide secure and reliable networking for smart home devices.
Developed by the Thread Group, an industry consortium including companies like Google, Apple, and the CSA, Thread offers a mesh networking solution that enables smart devices to communicate seamlessly with each other, creating a more efficient and robust smart home ecosystem.
How Does Thread Work?
Thread works by creating a mesh network where devices, known as “nodes,” communicate with each other to relay data across the network.
This allows the network to self-heal and maintain connectivity even if one or more nodes fail.
Thread uses the IPv6 addressing scheme and is built upon the IEEE 802.15.4 radio standard, which ensures a high level of compatibility with existing smart home devices.
Advantages of Thread
With a Thread network, you get the following benefits:
- Mesh networking: Thread's mesh network architecture allows devices to communicate with each other, ensuring a more extensive and robust network coverage. This also enables the network to self-heal and maintain connectivity even if one or more nodes fail.
- Low power consumption: Thread is designed for low-power devices, making it ideal for battery-operated smart home devices that need to conserve energy for extended periods.
- Scalability: Thread networks can support hundreds of devices, making it suitable for large-scale smart home installations and IoT applications.
- Security: Thread incorporates end-to-end encryption and authentication protocols, ensuring secure communication between devices and protecting against unauthorized access.
- Interoperability: Thread uses standard IPv6 addressing and is built upon the IEEE 802.15.4 radio standard, promoting compatibility with existing smart home devices. Additionally, its integration with the Matter smart home standard further enhances interoperability.
Disadvantages of Thread
All networks have their downsides. Here are some of the limitations of Thread.
- Limited adoption: Although Thread is gaining traction, it is still not as widely adopted as other smart home protocols like Wi-Fi, Zigbee, and Z-Wave. This can limit the availability and variety of compatible devices.
- Range: Thread's range is shorter than Wi-Fi due to its lower power consumption. However, the mesh network architecture can compensate for this limitation by using intermediate nodes to relay data.
- Complexity: Setting up and managing a Thread network may be more complex than using a traditional Wi-Fi network, particularly for users who are not familiar with mesh networking concepts.
- Bandwidth: While Thread is suitable for low-power smart home devices, it may not provide sufficient bandwidth for data-intensive applications or high-definition video streaming. That is where Matter-over-Wifi comes in, for the Matter protocol.
- Dependency on a Border Router: To connect a Thread network to the internet or other IP-based networks, a Thread Border Router is required. This adds an extra layer of complexity and possibly cost to the setup (Although some popular smart home devices are getting firmware updates to become border routers).
Types of Thread Devices within a Network
Within a Thread network, there are three primary types of devices that work together to form a robust and efficient mesh communication system:
Routers are responsible for relaying data between devices within the Thread network, ensuring that information is transmitted efficiently throughout the mesh. Routers maintain the network's topology and can dynamically adapt to changes, such as device failures or the addition of new nodes.
Typically, routers are always-on devices that are powered by a constant power source. Examples of routers include smart thermostats and smart home hubs.
The Leader is a special type of Router with additional responsibilities. The primary function of the Leader is to manage the overall network and ensure smooth operation. There is only one active Leader in a Thread network at any given time, but any Router can potentially become a Leader if the current Leader fails or becomes unreachable.
Router-eligible End Devices (REEDs)
REEDs can serve as both end devices and routers, depending on the network's needs.
When the network requires additional routers to improve connectivity or provide redundancy, a REED can upgrade itself to a full router role.
When functioning as an end device, a REED can communicate with other devices within the network and also route data if necessary. Examples of REEDs include smart light bulbs and smart plugs.
End devices, also known as “sleepy end devices” or “minimal Thread devices,” are typically battery-operated and low-power devices that communicate directly with their parent nodes (either a Router or a Router-eligible End Device).
These devices spend most of their time in a low-power sleep mode to conserve energy and only wake up when they need to send or receive data.
Examples of end devices include smart door locks, temperature sensors, and window sensors. For more check out my list here.
What is a Thread Border Router?
In addition to these three primary device types, there is also the Thread Border Router. A Thread Border Router is a device that connects a Thread network to other IP-based networks, such as Wi-Fi or Ethernet. It is the equivalent of a Zigbee or Z-Wave gateway.
This connection allows Thread devices to communicate with devices on other networks and access cloud services, enabling remote control and monitoring of the smart home ecosystem.
A Thread Border Router can be a standalone device or integrated into other smart home devices, such as a smart speaker or display (like the Google Nest Hub) or a mesh Wi-Fi device (like the Amazon Eero).
What is the difference between a Thread Router and a Thread Border Router?
A Thread Router is a device (like a smart plug) that maintains a Thread network's stability and efficiency by routing traffic and adapting to changes. While a Thread Border Router connects the Thread network to external IP-based networks, facilitating communication with outside devices and providing additional features like network management and security.
How Secure Is Thread?
Thread was designed with security in mind. It uses secure protocols and encryption to protect communication between devices.
Thread employs a combination of AES-128 encryption, public-key cryptography, and message integrity checks to ensure data confidentiality, authenticity, and integrity.
In addition, Thread networks also require devices to be authenticated and commissioned before they can join, adding an additional layer of security. (Unlike Zigbee which has optional commissioning)
How Far Can Thread Transmit?
The transmission range of Thread depends on various factors, such as the environment, device type, and radio power output.
In ideal conditions, a single Thread hop (communication between two devices) can cover up to 100 meters (328 feet).
However, because Thread forms a mesh network, the effective range can be extended by adding more devices (routers) that act as repeaters.
Are All Thread Devices Repeaters?
Not all Thread devices are repeaters. As mentioned, in a Thread network, there are Router-eligible Devices (REEDs) and End Devices. REEDs can become Routers, which act as repeaters, relaying messages between devices and extending the network's range.
End Devices, on the other hand, do not have routing capabilities and can only send and receive messages directly to and from Routers or the Border Router. These are usually battery-powered and operate in a low-power state most of the time.
Thread routers are typically AC or DC powered so they have the constant energy to transmit messages across the mesh network.
What is Matter-over-Thread?
Matter is an open-source, royalty-free smart home standard developed by the Connectivity Standards Alliance (CSA).
It aims to simplify and unify the smart home ecosystem by providing a common application layer for different IoT protocols. Matter-over-Thread refers to the use of Matter as the application layer running on top of the Thread network layer.
Thread, being an IPv6-based networking protocol, is compatible with various application layers such as OpenThread and Thread Group's Dotdot. So while Matter is a major application layer designed to work with Thread, it is not the only option.
How does Thread compare to Wi-Fi, Zigbee, and Z-Wave?
Thread excels in low-power, scalable, and secure mesh networking. It provides robust, self-healing connectivity, but has limited adoption at present compared to other protocols. Wi-Fi is widely adopted and supports numerous devices, offering high bandwidth and range. However, it consumes more power and has limited scalability due to its reliance on central hubs or routers.
Zigbee, like Thread, features low-power mesh networking with a large device ecosystem. It requires a Zigbee hub for integration with non-Zigbee devices and may experience interference with Wi-Fi in the 2.4 GHz band.
Z-Wave focuses on low-power communication, and avoids Wi-Fi interference by operating in the sub-GHz frequency band, but supports fewer devices. Despite the fact that it has a lower frequency, it actually has a shorter range than Wi-Fi due to its reduced power output.
Recent Thread Articles
I regularly post articles about Thread technology, so check out my latest articles below.