Commissioning connected lighting networks: Theory and practice, challenges and opportunities (MAGAZINE)

SIMON SLUPIK and SIMON RZADKOSZ describe the onerous challenge of commissioning wireless smart lighting networks and how provisions in the Bluetooth Mesh standard can simplify the process.

With constant technology advancements and growing market awareness, we are all getting more and more familiar with various aspects of wireless solid-state lighting (SSL) controls and the march toward smart lighting and the Internet of Things (IoT). However, the commissioning process still seems not to be getting the attention it deserves. Let’s break it down into pieces, while looking at how the Bluetooth Mesh standard addresses major commissioning challenges.

Despite the fact that you see many manufacturers touting simple commissioning via smartphones and tablets (Fig. 1), commissioning is recognized to be one of the more difficult issues for developers of connected LED lighting systems. This is partly due to the technical complexity of wireless lighting control technologies in general, but also due to multiple limitations that different wireless protocols impose in this regard. Developers have a multitude of ideas for overcoming these limitations. Some work better, some not so well, but it seems that we’ll have to be very patient while waiting for any sort of a common, agreed-upon approach to commissioning of smart lighting installations.

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To proceed with wireless commissioning, you need to forget everything you know about commissioning of traditional, wired systems. In the world of wireless lighting controls, this is just a completely different procedure that requires a new mindset and new tools. But before discussing different tools and possibilities, let’s see what commissioning really stands for in a connected environment.

Regardless of the wireless technology used, the commissioning process can be broken down into three major stages: network formation, device identification/mapping, and logic configuration.

Network formation

Smart lighting installations are, at their core, nothing but IT networks. The most important rules governing the way in which connected luminaires and sensors communicate with each other derive from the principal communication paradigms that the IT industry has developed for its needs. This fact is a blessing and a curse at the same time. On the one hand, these are mature, reliable processes that have proved effective in multiple applications; on the other hand, the connected lighting environment is one of a kind. With low computing and memory resources, ensuring robust communication in dense commercial installations is very difficult. Not all the rules that proved effective in classic IT networks are equally effective in smart lighting systems. The communication models applied to wireless lighting controls are likely to evolve as time goes by, but we’ll get back to this later. Now let’s focus on the consequences of the IT nature of connected lighting installations.

From the beginning to the end, the network formation process is a typical IT procedure. Adding devices to a network might not seem like a particularly challenging task, but it gets tricky when you’re commissioning a 10-story office building with thousands of network nodes, including luminaires, sensors, switches, gateways, and so on. The process is also sensitive from the point of view of network security (http://bit.ly/2ypuXIh). Many — if not the majority — of security flaws identified in connected lighting solutions relate to the onboarding. This is because letting an unknown device into a network is a potentially vulnerable operation. When joining the network, such a device learns the network’s security keys, so appropriate authentication measures need to be deployed to prevent these keys from leaking outside. What is crucial is the secure delivery of these keys. Effective authentication mechanisms also prevent potential intruders or Trojan horses from sneaking into the system when a new device joins the network.

The network formation is the part that is often completely ignored in marketing materials from smart solutions suppliers or during presentations given at SSL industry events. But don’t be fooled: Wireless commissioning doesn’t start with locating the right luminaires and setting up relevant interactions. The network must be formed first, and it’s a time-consuming process that requires IT engineering expertise and therefore generates significant costs.

Device identification and mapping

Once a wireless network is formed, all its nodes need to be physically identified and mapped on a floor plan. Only then is it possible to set up desired interactions and scenarios. The problem is that when communication happens via a gateway — which is the case for almost all the wireless technologies used in connected lighting systems — the commissioning device (a smartphone or a tablet) is isolated from the network in a sense that it’s impossible to tell how far individual nodes are located from the commissioning device. So if you’re commissioning a network in a multi-story office building, you can’t even tell which nodes displayed in your smartphone app are located on the floor that you’re currently trying to set up.

Developers are trying to solve this issue by implementing all sorts of experimental solutions, although there is always a price to pay in the end. At one recent industry conference, we even saw prototype drivers integrated with barometric sensors only for commissioning purposes. They allow for determining the precise altitude of an installed driver, so that the person responsible for commissioning can at least say on which floor a particular device is located. Then, the precise location of a given luminaire can be determined (and marked on a floor plan), e.g., by forcing that luminaire to blink during the commissioning process. This solves the identification/mapping issue to some degree, although the question is whether barometric sensors is what we really need inside our luminaires.

Logic configuration

Once the network has been formed and all its nodes have been identified and mapped, the logic configuration of the entire installation must be set up (Fig. 2). This process implies specifying all the interactions between all devices within a network. Relevant switches must be assigned to appropriate luminaires, the sensory infrastructure needs to be configured to trigger desired events and scenarios appropriately, and all operational parameters must be adjusted so the system operates as desired (or as required by building energy codes).

This configuration stage is, again, a time-consuming procedure that requires dedicated software tools. The design of these tools is going to have a profound impact on how intuitive and user friendly the commissioning procedure is. If commissioning software hasn’t been developed particularly well, setting up a room with a handful of fixtures might still not be such a struggle, but commissioning an entire office building can easily turn into a real nightmare.

Putting the pieces together

As you can see, these three major stages of the wireless commissioning process are very different from each other. This realization means that in a vast majority of cases, you will need dedicated software tools and dedicated competencies for each of them. When a network needs to be reconfigured for whatever reason, relevant actions will also need to be carried out within each of the aforementioned areas. This fact obviously generates additional commissioning and maintenance costs.

Furthermore, connected lighting systems based on the so-called patchwork wireless frameworks (e.g., Dotdot over Thread; http://bit.ly/2yqAiiI) have even more challenges to deal with. Since completely different technologies are used to handle typical networking tasks and logic configuration activities, it might be very difficult to coordinate certain issues that come up at points where these technologies directly meet with each other. Software tools used by each of them are not going to cooperate in any way, so even deeper specialist intervention might be required, and even higher costs might have to be borne.

As you can see, commissioning of connected lighting systems is quite a complex process with multiple challenges along the way, and multiple competencies are needed to handle it properly. It is therefore not surprising that suppliers often prefer to steer away from this subject when talking about their solutions. The history of connected lighting is simply too short, and there are still too few real-life implementations and too many different underlying technologies — with their own bottlenecks and restrictions — to say which approach is the right one. Just like the entire smart lighting environment, the wireless commissioning experience is likely to vary strongly between different systems and technologies.

In the remaining part of the article, we’ll look at how this process is handled by Bluetooth Mesh networking, a globally interoperable wireless standard that was adopted last year (http://bit.ly/2tafCGu). Just like in the case of wireless communication itself, Bluetooth Mesh introduces several innovative concepts also with regard to commissioning, streamlining the process in a way that no other wireless technology does. See our earlier article on the new standard for more details on Bluetooth Mesh (http://bit.ly/2MCwpKE).

Commissioning Bluetooth mesh networks

In Bluetooth Mesh networking, commissioning remains a process that involves the same three major phases: network formation, device identification/mapping, and logic configuration. In a wireless environment, there is no escape from this pattern. But at each of these stages, it provides smart solutions to some big challenges. Moreover, Bluetooth Mesh automates parts of the process (Table 1).

It starts with the network formation. Since the Bluetooth radio can be found in any smartphone/tablet on the market, such devices can be used as network provisioners if a relevant app has been installed that reliably and securely supports all the required processes. A provisioner is a node that is capable of adding new devices to the network. An unprovisioned device cannot send or receive any network messages. But the Bluetooth radio allows it to advertise its presence to a provisioner. The provisioner (smartphone/tablet) can invite such a device into a network, and once it is authenticated, security keys can be exchanged. This is when a device becomes a full-fledged network node.

As already mentioned, the exchange of security keys is a particularly sensitive process. In Bluetooth Mesh networking, depending on the capabilities of the unprovisioned device, the provisioner selects a suitable authentication method and notifies the unprovisioned device of the approach that is to be taken. Then both devices generate an elliptic curve public–private key pair and exchange public keys. Each of them calculates a symmetric key using its own private key and the peer device’s public key. From this moment forward, the symmetric key is used to ensure secure data transfer between the two devices.

What’s important, from the perspective of both network formation and other stages of commissioning, is that no gateway is needed to connect with individual nodes and set up the entire mesh network. Bluetooth is the only radio technology that allows for forming the network without touching the building’s core IT infrastructure. The process doesn’t require any gateways or Internet connection, so there is no need to obtain any formal agreements from the IT department — a process that can take much longer than one might assume. It can actually take months in the case of more sensitive buildings, such as banks or hospitals.

When it comes to device identification and mapping, Bluetooth Mesh offers significant advantages over other wireless technologies. This fact, to a large extent, also results from the fact that wireless communication happens with no gateway in between. Since a smartphone can connect with any other node directly, Bluetooth’s RSSI capability (received signal strength indication) effectively solves the problem of device identification. Simply put, when your smartphone is communicating with a particular network node, it can tell how far this node is from the smartphone. In practice, a smartphone app can use the RSSI filter to narrow down the list of displayed luminaires and sensors to those that are located in your immediate vicinity. This makes device identification and mapping a truly user-friendly process, while not requiring barometric sensors or any other strange inventions (Fig. 3).

Bluetooth logic configuration

Moving to logic configuration, Bluetooth Mesh introduces a revolutionary approach that the connected lighting industry has not yet been able to experience. It is called information-centric networking (ICN). This concept was initially presented as an approach to evolve the Internet infrastructure and support its dynamic growth by introducing uniquely-named data as a core Internet principle. Moving away from a host-centric paradigm, the ICN model doesn’t care about senders, recipients, or addresses. Instead, named information is its focal point, making data independent from location, application, and storage.

With Bluetooth Mesh, the ICN concept makes its way to the lighting industry. This implementation is realized through a fully decentralized architecture with no single points of failure, as well as the innovative publish-subscribe communication architecture.

The host-centric paradigm is the approach that has been used in all connected lighting solutions so far. And it didn’t prove efficient enough. With all the conflicting requirements of the connected lighting environment, we’ve seen low-power, low-bandwidth communication technologies being unable to deliver wire-like reliability and responsiveness in large-scale installations. With its publish–subscribe paradigm, Bluetooth Mesh moves away from a host-centric framework, enabling efficient multicast and peer-to-peer communications.

Data generated by intelligent sensors becomes addressable information. Since addresses of individual nodes don’t matter, sensor data is the focal point; other nodes subscribe to it and respond accordingly. Just like in the case of the ICN-based approach to the Internet infrastructure, this generates multiple benefits: improved spectral efficiency, better robustness, and full scalability. This is what makes Bluetooth Mesh capable of handling even dense connected lighting networks found in commercial buildings. But it also radically simplifies the maintenance of smart lighting networks.

In practice, this architecture means that during the final stage of the commissioning process, addresses are assigned to information, not to specific devices. So occupancy status for a particular room has its own address. The ambient light level in that room has an address, too. And it doesn’t matter how many sensors contribute to those parameters. Luminaires are subscribed to these addresses, not to individual sensor devices. Such an approach solves a number of issues, one of them being device replacement. If a luminaire requires replacement, the new one only needs to be re-subscribed the same way as the previous one. There is no need to change anything in the configuration of sensors interacting with the replaced luminaire.

In Bluetooth Mesh networking, the logic configuration stage can also be carried out using a smartphone or a tablet with a dedicated app. Such an app can provide provisioned network nodes with necessary application keys, while also assigning publish and subscribe addresses. This procedure allows them to communicate with other nodes of a mesh lighting network. Finally, a smartphone app can also be used to configure groups and scenes and to adjust any operational settings.

Commissioning made easy

Last but not least, Bluetooth compacts these three major commissioning stages into a single, streamlined, and time-efficient process. The network technology provides multiple commissioning advantages relative to other wireless network options (Table 2). The Bluetooth radio covers all the layers of the OSI (Open Systems Interconnect) communication model, which makes it capable of dealing — on its own — with all relevant processes both at the networking/transport level and at the application layer. There is no need to have multiple different software tools and different experts performing individual stages of commissioning. With Bluetooth, these stages can all be handled as part of one smooth procedure. A person responsible for commissioning walks into a room, uses the RSSI filter to narrow down the list of nearby luminaires and sensors, and clicks desired devices to identify them and map them on a floor plan. The network is formed automatically, and all relationships are configured in one go.

With the first wave of Bluetooth Mesh-enabled devices already on its way to the market, we’ll soon be able to verify whether the wireless commissioning process can indeed be so intuitive and easy. Much still depends on the design and capabilities of dedicated software tools intended for commissioning, but the Bluetooth Mesh technology itself provides a solid backbone for redefining the wireless commissioning experience.