BLE packet drops when Bluetooth and BLE are simultaneously in use

Question

I am using BLE v4.1 for my application where I am able to transfer 200 packets of length 20 bytes each from peripheral to central side.

I want to transfer data via BLE and play some music while the data is being transferred. The music file is available locally and will be played on earphones(can be wired or wireless BlueTooth earphones)

I am facing an issue of packet drops around 15-20% when I am playing audio through wireless earphones while data is being transferred via BLE and audio is played on phone Bluetooth earphones(tried on Android and iOS, both) simultaneously.

With wired earphones connected; there is no issue, I can transfer data via BLE and play audio smoothly without any issue but things are different with wireless Bluetooth earphones case. I tried it with different Android phones(Android 11, different manufacturers) and different BlueTooth earphones, the issue still exists.

What could be a cause for the same and how can I debug it?

Answer 1

Bluetooth and Bluetooth Low Energy has only one radio that can only do one thing at a time. The connection events are scheduled and cannot overlap. This means the throughput is shared among all connected devices. You will get a higher throughput per device with only one connection than with two connections.

You will have to experiment with connection interval and connection event length to find parameters that seems to work, and test with multiple Bluetooth controllers (phones), since all have different scheduling algorithms.