What technique is more suitable for multiple (10+) simultanious bluetooth communications? CC2564

Question

I am developing an industrial hardware that communicates via BLE 5.0. The design is this: multiple devices: (10, 20 devices) communicates with an high bitrate (around 20 bytes every 50 ms, so around 150 3.2 kbps). Sometimes is also the central that communicates, but it is mostly peripheral vs. central.

I am developing this architecture with CC2564 trasmitters (https://www.ti.com/lit/ds/symlink/cc2564.pdf?ts=1616973324278&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FCC2564).

Now, I have the next choices:

1. pairing all devices, before the transmission
2. connect via BLE connection, without pairing, and manage data trasmission using carachteristic read or write.
3. not connecting devices, but transmit messages using advertisement system.

The question is: what approach would you use to avoid collapsing data, increase the range and the reliability of the trasmission, that is crucial, and avoid losing data, or, even worst, the connection?

Do you see any possible problems that I should know or intrinsic limit of bluetooth for this kind of application?

Thank you for your suggestions.

Answer 1

I feel you are trying to overstress the BLE architecture. An attribute send each 50ms from 20 nodes would need a central with a connection interval of 2.5ms. Too bad that the minimum is 7.5ms (exactly six 1.25ms ticks)

I think you should review your bandwidth need and maybe use another kind of protocol.

This of course if the master actually support 20 connected nodes. When transmitting data in the advertising protocol (i.e. as a beacon) the limit goes up to 20ms but it's quite possibile that some conflict would happen: the idea is that even if one advert is jumbled the next one will more or less arrive correctly (but of course the air will saturate)