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Concurrent connections is the limit really 20 ?

I am trying to make a large BLE sensor network, hypothetically anywhere from 20-100 devices in a STAR configuration. I see there is a 20 max limit on concurrent connections. Does that mean I can only have 20 paired devices or can I have X number of devices paired, but only 20 connection within that moment. For example. If I am posting a message once every 30 seconds or 1 minute, I wouldn't have much overlap in TX messages from each end node. I was looking into the ANT+ profile but the range is short and I want the largest range BLE can take me. I also want to have ACK packets and possibility to do OTA firmware upgrades.

So I guess, when building a large network, what is the true definition of "concurrent connection" and what is the recommended way to build a large network with infrequent single packet messages?

  • The S140 can handle 20 concurrent connections. The limitation is in the SoftDevice's scheduler. 

    The maximum number of bonded devices depends on how much memory you've got and how much memory is required for each bond depending on the content of the bonding information. 

    The difference between ANT and BLE is not that huge at -2dB. 

    If you can use a mesh network I would rather use BLE mesh or OpenThread. 

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