Low Latency Connection to 25 BLE peripherals

[jmag999]

Here are my system requirements:

A single "Controller" needs to send 4 bytes of data per node.

There are 25 nodes in a system (100 bytes total payload).

All nodes must receive the data within a 100ms window.

The data is continuously sent by the controller.

What is the best way to accomplish this over a BLE connection?

We started by using a connectionless design where the "controller" rotated through 4 advertisements every 20ms.  The problem is that there is so much interference that the nodes which are scanning for the advertisements often miss them, and therefore take longer than 100ms to receive.  Should this design work, perhaps we are doing something wrong.  Our offices have many BLE devices advertising within RF range of the system.

Is there some other method we should consider?

[Petter Myhre]

Are the nodes scanning 100% of the time?

You are rotating 25 different advertisements in 100 ms?

I'm not sure what other data you have in your advertisements, but maybe you have space to have the data of several nodes in each advertisement? Then you wouldn't have to rotate that often, and the nodes would have several chances to receive the advertisements.

Other than that, I don't see any way of improving, other than rotating more often.

I guess you also could try a design based on connections, but our SoftDevices support a maximum of 20, so you would have to do some kind of rotation there as well.

[jmag999]

I need 4 packets per 100ms if they are 31 byte advertisements to cover all 25 peripherals.