From Zigbee to Matter: Understanding Their Relationship

First, let me express my intention. I am a technical professional rooted in the IoT industry for many years, and I was fortunate enough to participate in the CHIP Working Group from the very beginning. Of course, my “participation” refers to becoming a member in early 2020, but for most of the time, I was just listening to various technical discussions in Tiger Teams. Over time, I became more familiar with the outline of CHIP. In May of this year, CHIP was officially renamed Matter, and at the same time, Zigbee Alliance was renamed Connectivity Standards Alliance. With more and more media coverage and discussions on various technical self-media channels, Matter is currently the most discussed and also the most mysterious new standard in the IoT industry. This public account will dedicate a series of articles to introducing, explaining, answering questions, and even promoting the new IoT application layer standard protocol Matter (after the official announcement of Matter 1.0 spec).

I will start this article with two questions. Here is a simple and clear image.

What is the relationship between Matter and Zigbee Alliance?

You may have heard that major players like Apple, Google, Amazon, SmartThings, and Comcast are actively promoting the formation and implementation of the Matter specification. If you have participated in this Working Group, you will find that the overall contribution from engineers and technical experts from Apple, Google, Amazon should exceed the total contribution of all other companies in terms of drafting specifications, outputting SDK code, and even the frequency of speaking in technical discussion groups. Of course, from the background of these major players, this pattern is easy to understand since they are all experts in standards, protocols, and software. However, Matter belongs to Zigbee Alliance. Yes, you heard it right, it belongs to the original Zigbee Alliance, now called Connectivity Standards Alliance (CSA). Here is an excerpt from an official statement: “The project, and the working groups for its development, maintenance, certification, and promotion, have been formed under the umbrella of the Zigbee Alliance — an open, global, non-profit standards development organization, that is best known for its development of Zigbee and related technologies.” So it can be simply understood that all documents and codes related to Matter, as well as future certifications and market promotions, are regulated by CSA.

Zigbee Alliance has always been a relatively open and inclusive organization. They have been continuously trying and exploring to find a better and faster technological direction for the development of the IoT industry. I want to emphasize that although I am a long-time fan of Zigbee, this is really not an advertisement. For example, they started contacting the Thread Alliance in 2016 and jointly released the “Dotdot over IP” standard with Thread in 2018. By 2018, Zigbee Alliance also led an independent technical working group “Zigbee Direct” to explore the technological and market advantages that the combination of Zigbee and Bluetooth could bring. What is rare is that most of the management in the alliance are quite visionary, especially the technical experts (most of whom are senior experts), who, with a beautiful vision for the future development of IoT, continue to engage their brains and contribute their time and energy to new ideas. The well-known “ZCL” and “Dotdot” can be said to be representative works of Zigbee Alliance, as their inherent flexibility and applicability are now widely used in different underlying communication technologies’ “data model” protocols. Even so, experts from Zigbee Alliance are still very concerned about the compatibility and interoperability between different protocols in the IoT industry and issues related to IoT security. So, in early 2018, Zigbee Alliance took the lead and united major IoT companies and even internet technology companies globally to jointly initiate the “One Data Model” specification applicable to various communication protocols and established the “ioXt Alliance” specifically for IoT security.

So, when Apple and Google, two companies that usually do not back down from each other, suddenly sit down calmly and say, “Let’s play together,” it must be attributed to Zigbee Alliance’s leadership. Because that is the greatness of Zigbee Alliance; they have clearly seen that one company dominating the current trend is unrealistic and abnormal. Only when industry giants can cooperate and take the lead in formulating and implementing new unified technical standards can this industry possibly achieve rapid promotion and rapid development. At that time, both Apple and Google will be direct beneficiaries of this technology. Thus, in mid-2019, under the leadership of Zigbee Alliance, after discussions among the aforementioned big players, CHIP was born. Therefore, it is not an exaggeration to say that Matter belongs to CSA due to Zigbee Alliance’s outstanding contributions and leadership.

What is the relationship between Matter and Zigbee?

There is no relationship; it is as simple as that. You can take another look at the first image I posted. Whether at the beginning or now, Zigbee and Matter are completely independent and entirely different protocol standards. Zigbee is based on IEEE802.15.4, using NWK short addr for addressing, which everyone knows well. As for Matter, all communication between nodes is based on IPv6-bearing networks. If you are still not convinced, just look at the image below, which clearly shows that Matter has completely separated from Zigbee.

I believe many viewers feel a chill in their hearts when they see this framework, then find it hard to believe that Zigbee Alliance has created a new protocol standard that has nothing to do with Zigbee!!! What are they thinking??? Are they abandoning Z for M??? However, if we change our perspective on this issue, if the leaders from Zigbee are playing together harmoniously, then the environment and tone for this play must be fair enough and sincere enough. Here, I boldly speculate that Zigbee Alliance must have made some sacrifices. Since we agreed to play together, I will lead by example and we will create a protocol standard that does not favor any party. To ensure fairness, each company can contribute its most advantageous and competitive parts, thus integrating into a brand new, nearly perfect standard. Thus, Apple contributed its HAP Secure Commissioning content, Google contributed its existing network layer and application protocol Weave for Smart Home, and Zigbee Alliance undoubtedly took its masterpiece Dotdot to do the application layer’s “data model,” which is simply unbeatable.

At this point, some people may say, didn’t you say there was no relationship? Isn’t this a relationship? Yes, if we reason this way, I can summarize two points of relationship: 1. Zigbee and Matter both belong to CSA; 2. Zigbee and Matter share a common data model, also called Data Model. But we can’t say that just because we are both Chinese and speak Chinese, we must have some relationship, right?

Since it has been established that there is no relationship, some people start to feel anxious. There will be the following arguments:

• Matter seems to not care about Zigbee; how will Zigbee play in the future?

• Now that Zigbee is independent, will CSA continue to maintain and iterate it?

As for what Zigbee should do, I originally wanted to write a separate article on this topic, but due to the high frequency of questions, I decided to conclude this article with this.

Zigbee to Matter Bridge

We can imagine how heartbroken companies like Philips Hue, Amazon, and SmartThings, which have previously invested heavily in Zigbee technology, must feel when they see the Matter architecture. But no matter how much they struggle, Zigbee cannot become IP-bearing. Regardless of the turmoil, they must gather their emotions and continue working. Thus, a brilliant idea was born.

Recognizing the reality, the aforementioned companies began to shift their focus from device nodes in the network to the control center of the network, the Hub (also known as gateway, control center). Since it is impossible for device nodes to directly enter the Matter network, the Hub must be IP-bearing. This way, the Hub has the possibility of being a Matter node. Since there is a possibility, if the Hub’s hardware resources are good enough, can I run an application similar to Matter Proxy on it to manage and maintain these Zigbee nodes? If I want to make it more user-friendly, I can even present these Zigbee nodes in the Matter network through Matter Proxy. If the application is well-made, I can even map all these Zigbee nodes as Matter nodes. As a user, it would be impossible to discern whether a device uses Zigbee technology or Matter technology, as they would all be mirrored as Matter nodes.

In this way, all incompatibility issues seem to be resolved. For a Zigbee Hub, all it has to do is upgrade its firmware, which is just a bit more coding work. Then the market can proudly tell customers that it doesn’t matter whether our devices are Matter or not; what matters is that you can play with us according to Matter’s way, and we support it.

Of course, behind what seems to be a simple firmware upgrade, the specification content of Zigbee to Matter Bridge needs to consider far more than these issues. I will write a separate article later to discuss the concept and architecture of the Bridge.

Finally, let us turn our attention back to the image I posted at the beginning of the article. Both Matter and Zigbee standards are firmly situated at the top of the CSA architecture, like two core pillars. The message conveyed here is that while CSA promotes the drafting and implementation of Matter, it will continue to maintain the iteration and updates of Zigbee technology. The two standards complement each other and are a strong support for CSA’s leading position in the industry. At the same time, let’s consider a question: even if Matter is officially released today, given Zigbee’s current market presence, do you think it is realistic for Matter to completely replace Zigbee in a short time? After all, new things must undergo the test of the market. Let us embrace new things with an open and inclusive attitude, staying true to our original intention to achieve lasting success.