6

We are trying to choose the most suitable connection protocol for wearable devices, with the following constraints:

  1. 300 - 500 devices will simultaneously connect
  2. About 1 km2 site area—coverage is needed throughout the site.
  3. Devices are moving
  4. This is an industrial site, and so there will be concrete and steel obstructions
  5. At least a 20 kilobyte datarate is necessary.

Update 7.12.2017

At the moment we are looking into:

  1. Bluetooth mesh networking (Bluetooth 5, BLE)
  2. LoRa
  3. Nordic proprietary protocol

Has anyone worked with those protocols and in conditions stated above?

  • 1
    Are they gonna be battery powered? – Helmar Dec 7 '17 at 6:13
  • 1
    Yes, about 190 mAh – dicobraz Dec 7 '17 at 15:36
  • Just curious, but how can you know the battery when you don't yet know the device? – Mawg Dec 11 '17 at 8:03
  • We do know the device, we are building it. This questions relates to communication protocol of our device, which we haven't decided upon. For the battery, it is quite simple in our case, we needed to get the biggest possible charge in the size we have. – dicobraz Dec 12 '17 at 9:00
  • 1
    Each device will emit 160kbit/s of data, continuously? Do you plan to recharge the 300 to 500 devices every day? – Sylvain Dec 29 '17 at 19:21
6

I would recommend some sort of mesh network, as obviously plain old WiFi or BT won't cover those distances. Zigbee is as good a candidate as any.

For hardware, AdaFruit does some good wearables, although if everyone has a smartphone, you might as well use those.

And, if you can figure out how to power it by battery, take a look at my answer to this question and the $20 Flutter :

Flutter is a high performance microcontroller platform for the connected age. Fast ARM CPU, hardware cryptography, battery charging, and onboard wireless with over 1 kilometer range. Easy to program with Arduino onboard.

enter image description here

.

enter image description here

  • 1
    Thank you! I think this is a very good piece of gear for DIY and hobby projects, but would be quite hard to integrate to production. I tried to look for the chip and protocol that it works with and as I understood it is based around TI wifi chip, do you know if it is the case? – dicobraz Dec 7 '17 at 15:52
  • 1
    I am afraid that I do not I can only suggest that you contact them & ask. I would be very grateful if you post your final decision, as this is something which I have thought of developing (for a non-profit) . Battery life is the problem; not sure about Flutter, or AdaFruit wearables, but also not sure if I can require everyone to carry a smartphone ... – Mawg Dec 7 '17 at 16:21
  • 1
    Sure thing, I updated the question today and keep updating as we are moving along. – dicobraz Dec 7 '17 at 16:27
  • 1
    The biggest problem with Flutter is that they hide the technical details of the radio very good. From the antenna it looks like a Sub-GHz transceiver, so I guess a CC1120 or a later product. If that is the case, the 1 km is challenging if the transceiver is not positioned on a long pole. – koalo Dec 9 '17 at 11:36
  • I totally agree (+1), but it still ought to be enough to cover the 300m asked for, don't you think? In the worst case, with "about 1 km2 site area", you might have to erect a few poles for repeater nodes, or add such noses to the sides of buildings. I guess that it depends how busy it is. If you are the first worker there in the morning, then there is no one there for you to mesh network with; as it gets busier, there should be people every 5 or 10m or so. – Mawg Dec 11 '17 at 8:03

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Not the answer you're looking for? Browse other questions tagged or ask your own question.