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Comment by Beretta_Vexee

7 days ago

There are already several open source implementations, but the Bluetooth SIG standard only supports flood propagation.

This is fine for managing a few hundred temperature sensors or lighting controls up to the building's floor concentrator, which is the main use case for this standard, but it is completely unsuitable for sending individual messages from user A to user B.

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Beretta_Vexee

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kragen  7 days ago

Flooding does work for sending individual messages from user A to user B at a small enough scale, but it gets progressively less efficient as the network grows, and at some level it will collapse.

  • Beretta_Vexee  7 days ago

    Flooding works if there is not too much hops between the sender and the recipient. For indoor IoT, it is very rare to have more than 3 hops and the data rates are extremely low and messages are just few bytes (on/off light, temperature).

    It would only take 4 people at 5 hops apart trying to exchange photos of less than a megabyte to completely saturate a network of hundred devices.

    • kragen  6 days ago

      It depends on how often they're exchanging those photos, but it doesn't depend on the number of hops, or even the number of nodes, just the total number of publishers and the bandwidth desired by each publisher. In flooding every message gets transmitted (eventually) by every device, so the bandwidth available for the average publisher is the bandwidth of the slowest device divided by the number of publishers, regardless of how many hops or nodes there are.

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