What is Thread?

A protocol that enables secure mesh communication between IoT devices with low power consumption

Thread overview

Thread is a network protocol designed under the leadership of Nest Labs, a Google subsidiary, that uses IPv6-based low-power mesh networking technology for IoT (Internet of Things) products, ensuring both security and future-proofing.

The Thread Protocol Specification is available free of charge but requires acceptance and ongoing compliance with an End User License Agreement (EULA), which states: "Implementation, practice, and shipping of the Thread technology and Thread Group specifications requires membership in the Thread Group."
Membership in Thread groups requires an annual fee, except for "Academic" and "Associate" membership.

Key features of Thread

Mesh network

By self-forming a mesh network that connects wireless devices like a mesh, it enables communication in places where radio waves normally cannot reach.
It is also robust because it has a backup system in place to ensure that any device in the network fails.

Native IP (Internet Protocol) communication

The Internet's IP communication network can be used for wireless communication as is.

User-friendly network management functions and high security

The process for adding new devices to the network has been devised, and security measures, which are becoming increasingly important in the IoT, have been implemented.

Long-term battery operation possible

Thread end devices can stay in sleep mode at their own discretion, enabling long-term battery life.

Thread uses 6LoWPAN (IPv6 over Low-power Wireless Personal Area Networks), which utilizes connected routers called edge routers, and uses the IEEE 802.15.4 wireless protocol for mesh communication, similar to ZigBee.
On the other hand, Thread also allows you to specify an IP address, and supports cloud Access and AES encryption.
This means that Thread maintains a high level of security by allowing only authenticated devices to join the network.
Additionally, all communications over the network are secured by a network key.

Thread Group

On July 16, 2014, the Thread Group Alliance was formed as a working group to promote the adoption of Thread, a wireless network protocol for smart homes that can be used by IoT products, with the aim of making Thread an industry standard and providing Thread certification to products from various companies.
Initial members were ARM Holdings, Big Ass Solutions, NXP Semiconductors/Freescale Semiconductor, Google subsidiary Nest Labs, O STATIC RAMS, Samsung, Silicon Labs, Somfy, Tyco International, Qualcomm and Yale lock company.
Apple Inc. joined the Thread team in August 2018 and released its first Thread product, the HomePod mini, in late 2020.

In 2019, the Connected Home over IP project (later renamed "Matter") was launched, led by major IT companies such as Amazon, Apple, Google, and Zigbee, as well as related organizations.
The main goal of the Connected Home over IP project is to enable devices from different manufacturers to work together seamlessly.
Leveraging Thread, Wi-Fi, and Bluetooth Low Energy technologies, we have launched a broad initiative to create a royalty-free standard and open-source code base to promote interoperability in home connectivity.

BSD license

The BSD license (Berkeley Software Distribution License) is one of the open source software licenses, and has the following main features:

Free use
You are free to use, modify, and distribute the software.
Copyright Notice
When distributing source code or binaries, the original copyright and license notices must be retained.
Fewer restrictions
It has fewer restrictions than other licenses and can be used commercially.

The open source implementation of Thread under the BSD license is called "OpenThread" and is released by Google. The BSD license is simple and flexible, making it popular with many projects.

short range wireless standard

Comparison of each technology

As shown in the diagram above, wireless technologies can be divided into WLAN, which is characterized by high-speed transmission; ANT, whose greatest strength is short-range wireless; Bluetooth, which excels at connecting with smartphones; ZigBee, which is not widely used in Japan but is popular worldwide; and Sub-GHz wireless and its extension systems, which can achieve a variety of frequencies and communication speeds with wireless frequencies up to 1GHz.

As can be seen from the table above, the international standard IEEE802.15.1 specifies a P2P, Star network topology.
This shows that if the IEEE802.15.1 standard is used as the base, only relatively simple network configurations such as P2P (1:1) and Star (1:N) are possible.
On the other hand, IEEE802.15.4 allows all network configurations, including P2P, Star, Tree, and Mesh.

ZigBee and Thread

ZigBee and Thread are often used almost interchangeably, but what the two standards have in common is that they are characterized by low power consumption and low data rates.
It is suitable for wireless communication over short distances and with small amounts of data while maintaining low power consumption for wireless control and monitoring applications in smart home spaces.

One of the key differences between ZigBee and Thread is that Thread utilizes Internet Protocol version 6 (IPv6).
Thread can connect to existing IPv6-based Wi-Fi networks in the same way.
ZigBee, on the other hand, requires building a network from scratch, with each node in the network getting a 16-bit address that must be converted to IP using an application layer gateway.
As shown in the figure below, Thread does not define the application layer, whereas Zigbee does.
For this reason, Threads are more flexible in terms of ease of application layer development.

Another difference is power consumption.
Thread is designed as a low-power protocol suitable for battery-powered IoT devices, using energy-efficient routing algorithms to minimize power consumption, allowing Thread devices to achieve long battery life by optimizing sleep periods and reducing energy usage during idle periods.
On the other hand, ZigBee is known for its low power consumption, but as shown in the diagram above, it tends to consume more power than Thread due to its large software stack.