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Taking a Closer Look at Bluetooth Mesh

  • 07.26.18
  • ::
  • By Matt Smith

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In this post, I want to focus on the concept of mesh networking technologies. There’s been a lot of coverage on mesh in the trades lately, and particularly on Bluetooth Mesh (BT Mesh), so wanted to clarify how we’re viewing the landscape right now.

In networked lighting control, mesh technologies use multiple nodes/devices in the network to dynamically shift the path of control messages to and from the end-devices being controlled. This is often referred to as a “many-to-many network topology.”

By using redundant nodes, and rapidly altering contol communication paths, mesh technologies hold promise for increasing overall communication speed and efficiency, reducing lag, and — perhaps most importantly — minimizing risk of total control failure should one node fail.


More from Matt Smith:
Why "The Cloud" Isn't Revolutionary
The Thing is Not the Commodity in the Internet of Things
 A New Hope for IoT Control: Why Alexa Stole the Show at CES 



The two most popular mesh options today include Bluetooth Mesh (a relatively new extension of the original Bluetooth standard) and Zigbee (a longstanding and mature standard that adopted mesh support many years ago).

You might already be thinking, “I know about Bluetooth!” You may even be thinking about how much you enjoy Bluetooth on your personal devices.

We do, too. However, Bluetooth Mesh is a technology standard all its own. It’s not the Bluetooth you use to connect your wireless headphones to your smartphone, but it is based on it.

In this blog, we’ll walk through what Bluetooth Mesh is, why it matters, and whether it’s truly ready for use in commercial networked lighting control solutions.

Note that we won’t be doing a lot of head-to-head comparisons of Bluetooth Mesh vs. Zigbee in this blog.

We may be doing that in the future, but, if you’re interested, there already have been deeper studies done on the differences between Bluetooth Mesh and Zigbee. One great example is the benchmarking examination from Silicon Labs.

So, let’s dive in!

What is Bluetooth Mesh?

You’ve certainly heard of Bluetooth, the short-range wireless technology that connects mobile and electronic devices.

Chances are that you use it in your daily life, such as making hands-free calls in the car or playing music through a wireless speaker in the backyard. These days, just about every mobile device on the planet has one of these RF receivers.

However, the original Bluetooth standard was not designed to be used in commercial and industrial IoT applications.

The original Bluetooth standard was optimized for one-to-one connections (e.g. headphones to mobile phone), so using it to control dozens, if not hundreds of lights in a building wasn’t feasible.

Bluetooth Mesh was recently created and adopted by the Bluetooth Special Interest Group (Bluetooth SIG) as an official communication protocol to adapt the original standard into something capable of operating in a many-to-many topology.

Using a many-to-many approach eliminates the need to directly connect the originating control device (such as a gateway) independently to each device being controlled.

Rather, control signals can be dynamically “published” to multiple nodes in the network using a “managed flood” approach in which nodes can broadcast messages to the entire network to be received by nodes that may “subscribe” to those messages.

This, of course, requires that a certain level of networking intelligence be built into each device, allowing them to participate in a managed flood mesh network.

This built-in device-level intelligence is therefore an inherent requirement for the Bluetooth Mesh standard.

Common Misconceptions about Bluetooth Mesh

The Bluetooth technology on your phone and the Bluetooth of Bluetooth Mesh are almost completely unrelated.

That’s just one of several misconceptions when it comes to Bluetooth Mesh technology and how it’s used. So, let’s talk through more of those before getting to the pros and cons.

Misconception #1: Bluetooth Mesh Is Already a Proven Technology.

Millions of devices use Bluetooth, so it’s an established, reliable technology by this point, right?

For one-to-one consumer applications, yes. For many-to-many commercial applications, no.

Remember that Bluetooth Mesh is brand new, having been conceived in 2015 and adopted in 2017.

Other standards, such as Zigbee, have been using one-to-many and many-to-many mesh technology for more than 15 years. (The Zigbee Alliance was established in 2002, and the first Zigbee specification was in 2004. It is worth noting that a number of different approaches to routing were tried and tested, and the current routing approach was finalized with the release of the Zigbee PRO stack in 2007.)

Since it’s so new (and, largely unproven), there’s still a lot we don’t know about how Bluetooth Mesh works, how it scales, and how it holds up in real world commercial and industrial applications.

Misconception #2: Bluetooth Mesh Uses Highly Efficient Dynamic Control Routing.

One of the biggest misconceptions that has been growing around Bluetooth Mesh is the idea that its many-to-many routing is somehow more sophisticated, optimized and efficient than other standards.

The reality is exactly the opposite—at least for now.

Rather than routing individual control commands individually through the most optimized path, Bluetooth Mesh networks send out multicast messages to many groups of devices searching for the target device(s).

The Bluetooth Mesh documentation actually refers to this as a “managed flood” of control signals, suggesting that this approach is actually a desirable feature and benefit. A “managed flood” is a kind of broadcast.

However, that can often result in unnecessary and inefficient RF messages that can create greater latency, missed commands and unecessarily high network traffic. In fact, the Zigbee specification limits the number of active broadcasts in a network due to the problems seen in over a decade of testing and real-world deployments.

Misconception #3: Bluetooth Mesh Eliminates the Need for a Gateway. 

A lot of excitement around Bluetooth Mesh technology centers arond the misconception that it will eventually eliminate the need for control gateways.

The idea here is that if you add enough routing intelligence into the devices/nodes in the network, the distributed intelligence can replace the need for a centralized intelligent gateway.

Based on our extensive testing, using multiple control protocols and standards (including Bluetooth Mesh), this unfortunately still falls into the “too good to be true” category. 

Again, based on exhaustive testing in our labs, the truth is that there are still critical reasons and clear benefits for using gateways.

You’ll recall that we posted a blog about why we believe gateways are still the best choice.

At least in the forseable future, gateways will continue providing fundamental features and benefits to your lighting control solution.

These include reduced latency, fast configuration of devices, over-the-air updating, creating a rich and useful user interface, and more.

Misconception #4: Bluetooth Mesh Simplifies the Commissioning of Networks.

While Bluetooth Mesh technology may make commisioning devices slightly easier by allowing a direct connection from a Bluetooth Mesh “thing” to a mobile device, our testing shows that today it’s really only useful for small solutions or in a small zone/area.

To elaborate, networks larger than one room or a handful of devices need batch commissioning. You wouldn’t want to commission a network of 100 lights by filling out a screen for each light, one at a time. Batch commissioning uses a gateway to quickly group “things” (lights, switches, etc.) into areas and create sets of rules for those areas based on common settings. Since a gateway with IP connectivity is involved, commissioning isn’t done device-by-device. So, the fact that it is slightly easier to get to a device really makes no difference on anything larger than a network with a handful of “things.”

That means that it’s not yet very realistic when it comes to commercial lighting for networking 10,000 to 150,000 square feet, or more.

Bluetooth Mesh Today: The Pros and Cons

Now that we have that out of the way, it’s important to point out that although Bluetooth Mesh is a new and relatively unproven technology, it does hold promise as a future technology.

Cortet is therefore actively monitoring the progress and evolution of Bluetooth Mesh, and consistently testing it for maturity and viability.

As a result of that testing, we’ve put together the following pros and cons to consider if you are currently evaluating Bluetooth Mesh based solutions.

PROS

  • Potential Benefits for Very Small Projects

While not yet reliable for large-scale projects where gateway intelligence is required, Bluetooth Mesh (in its current state) may simplify build-out and perhaps commissioning for small projects where a gateway (and the features it brings) isn’t necessary.

This would include projects involving only one or two offices, or a small number of cubicles, with just a few devices connected in close proximity—such as a single wall switch connected to a single occupancy sensor and perhaps one or two fixtures.

Because there is no gateway involved in this type of implementation, there may be no need to engage the company’s IT department, possibly providing a cost and speed advantage.

Further, initial commissioning and setup in this type of small project can realistically be done through a direct Bluetooth connection between the devices and the installer’s mobile device, providing further advantages in cost, simplicity and speed.

  • Possible Pricing Benefits from Economies of Scale

While the Bluetooth Mesh standard is very new, the fact that the traditional Bluetooth technology is so widespread and generally well-received means that there’s a vast selection of Bluetooth based RF chips on the market.

This near ubiquity of standard Bluetooth chips, if able to be used in many-to-many topologies, could lead to lower price points as Bluetooth Mesh continues to advance.

Theoretically, lower price points could lower device costs for OEMs, which could speed adoption and investment across the commercial market.

CONS

  • Questionable Scalability and Routing Efficiency

While Bluetooth is widely known and accepted for one-to-one connectivity, it is largely untested in large-scale connected environments.

In fact, Silicon Labs (who sells Zigbee and Bluetooth Mesh chips) determined that Bluetooth Mesh experiences the largest increase in latency of any mesh option as a network size grows.\

In testing, Bluetooth Mesh’s “managed flooding” routing style creates unnecessary “noise” that can confuse RF signals and delay or interrupt commands.

  • Unproven in Real World Deployments

While Bluetooth Mesh is enjoying a lot of buzz at the moment, there are very few devices commercially available and even fewer deployments.

At the time of this writing, the standard can only be described as nascent and unproven, since there really is no track record developed. We’ll be watching closely as its status progresses.

The Future Holds Promise

We know new technologies can mature and cross over into mainstream adoption quickly, and we’re confident that Bluetooth Mesh will continue being improved and refined. There are a lot of smart people working on Bluetooth Mesh, and eventually it will be ready.

We at Cortet continuously strive to provide our Cortet Certified and Powered by Cortet partners with the best, most reliable technology options available.

Today, we are fully committed to Zigbee across our portfolio due to its maturity, proven track record and tested superiority. But, that doesn’t mean we won’t categorically rule out a move to Bluetooth Mesh in the future—it all depends on how it matures.

For Next Time...

The Zigbee 3.0 specification has now been available for a year. Since most Zigbee devices today still use Zigbee HA 1.2, this sounds like a big change and, potentially, a big problem.

In my next post, I will talk about the reasons for creating Zigbee 3.0, when to expect it will be “real,” and how existing Zigbee 1.2 networks can be migrated to Zigbee 3.0.

We'd love to hear your feedback, so please leave us comments below or send email to marketing@cortet.com. Also, be sure to subscribe to our email alerts and follow us on LinkedIn, Twitter and Facebook so you never miss a thing.


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Fixture vs. Area-Based Control: The Pros and Cons

  • David Parrett
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  • 07.09.18

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