editor's blog
Subscribe Now

The Internet of Lightbulbs

iStock_000016897113_Small.jpgBased on a solution just announced by CSR (now part of Qualcomm), you can outfit your new building with lights – and your network will be in place.

OK, they’re not positioning it to replace your Ethernet plant, perhaps, but it could become part of the network. They do this by making each LED lightbulb fixture also a Bluetooth mesh node. In case you missed the news early last year and are objecting that Bluetooth doesn’t have a meshing feature, you’re right – the standard doesn’t. CSR has overlaid the capability in a proprietary offering.

The lighting solution they’re announcing now provides both Bluetooth beacons – supported by the standard – and meshing. They set up and manage the beacons using the mesh; once up and running, the beacons operate independently of the mesh.

But this does raise some questions – especially as Greenpeak founder and CEO Cees Links questioned Bluetooth mesh latency in a conversation we had at Imec’s ITF in Brussels early this summer. The point being that, you might be able to create a mesh, but would it have characteristics that make it useful? Apparently folks tried to mesh WiFi at some point… and that has not become a thing. A reasonable question…

So I asked CSR for some more detail on their latency. And this resulted in a broader explanation of how they handle meshing.

They do what they call “flood meshing” instead of routed meshing. In other words, they start a message going and it follows all routes until a time-to-live flag expires, indicating that a particular trajectory has involved too many hops and should just stop. Presumably, at least one route will take the message to its intended receiver. Nodes keep track of messages they’ve received so that the flood doesn’t reverse.

This is actually more nuanced than it sounds. For power reduction purposes, each node in the mesh wakes up occasionally to see if there’s any message. This means that, at any given time, some number of the nodes in the mesh will be asleep and miss the message. So this flood doesn’t actually cover all nodes – just the ones that happen to be awake at the right time.

To increase the likelihood that nodes can pick up the message and run with it, each node advertises the message on 3 channels 6 times. You can ask for an acknowledgment, but it’s not required. The design of the mesh and the specific timing have to balance the likelihood of at least one node listening at any given time against the power required to listen. Obviously, the denser the network, the better your chances of your message propagating.

A network is protected by an overall network key, keeping networks from leaking information into each other (presumably). A network is also a virtual entity overlying the specific devices – meaning that an individual light bulb, in this case, could participate in more than one network.

And as to that original latency question, best-case single-hop latency is around 15 ms. From a quick check on my part, this doesn’t seem too different from Zigbee. They’re a bit hard to compare directly, since Zigbee uses routed meshing, and may need to request a route before sending a message – which adds to the latency for such instances (routing tables presumably make that necessary only for new destinations). But delivery in the range of 15-100 ms or so doesn’t seem unreasonable for either one.

You can read more about their lighting solution, done in conjunction with SK Telecom, in their announcement.

Leave a Reply

featured blogs
Jul 1, 2022
We all look for 100% perfection and want to turn our dreams (expectations) into reality as far as we can. Are you also looking for a magic wand to turn expectation into reality? The story applies to... ...
Jun 30, 2022
Learn how AI-powered cameras and neural network image processing enable everything from smartphone portraits to machine vision and automotive safety features. The post How AI Helps Cameras See More Clearly appeared first on From Silicon To Software....
Jun 28, 2022
Watching this video caused me to wander off into the weeds looking at a weird and wonderful collection of wheeled implementations....

featured video

Multi-Vendor Extra Long Reach 112G SerDes Interoperability Between Synopsys and AMD

Sponsored by Synopsys

This OFC 2022 demo features Synopsys 112G Ethernet IP interoperating with AMD's 112G FPGA and 2.5m DAC, showcasing best TX and RX performance with auto negotiation and link training.

Learn More

featured paper

3 key considerations for your next-generation HMI design

Sponsored by Texas Instruments

Human-Machine Interface (HMI) designs are evolving. Learn about three key design considerations for next-generation HMI and find out how low-cost edge AI, power-efficient processing and advanced display capabilities are paving the way for new human-machine interfaces that are smart, easily deployable, and interactive.

Click to read more

featured chalk talk

Seamless Ethernet to the Edge with 10BASE-T1L Technology

Sponsored by Mouser Electronics and Analog Devices

In order to keep up with the breakneck speed of today’s innovation in Industry 4.0, we need an efficient way to connect a wide variety of edge nodes to the cloud without breaks in our communication networks, and with shorter latency, lower power, and longer reach. In this episode of Chalk Talk, Amelia Dalton chats with Fiona Treacy from Analog Devices about the benefits of seamless ethernet and how seamless ethernet’s twisted single pair design, long reach and power and data over one cable can solve your industrial connectivity woes.

Click here for more information about Analog Devices Inc. ADIN1100 10BASE-T1L Ethernet PHY