Trying to get ZERO Data loss/Packet drop while communicating over BLE-UART. Any Suggestions.

[RohanKadam]

Scenario:

We have three verticals in our project. The nrf51822 based device, base station (BS) and server running on cloud.

Problem Statement:

I need to continuously (every 50msec) send value from nrf51822 to base station. Base station also needs to update received data on server. I miss out few packets when BS performs server update.

Solution we tried was:

1. Re-transmit on No ACK from BS. But re-transmission is not feasible since next data arrives at next 50 msec mark.

2. We buffered the data at nrf51 side and send it with timestamp (since timing is important for Analytic team) to tackle fresh data at every 50 msec interval problem. But since throughput of BLE-UART is limited to 23 Bytes, I didn't suceed in sending entire packet with timestamp included in it.

Any suggestion will be very much helpful. Thank you.

[Einar Thorsrud]

Hi,

BLE is reliable, and you will always get retransmissions on the link layer. You write that retransmission is not feasible due to the needing data every 50 ms. Why is that, is the chunk of data you need to transmit every 50 ms larger than you can fit in one BLE packet? You could set the connection interval down to 7.5 ms making time for several retransmission (assuming you only need one packet for each chunk of data).

BR,

Einar

[RohanKadam]

Thanks for the reply Einar Thorsrud. 

I would surely try out your suggestion. The only drawback I see is it might increase power consumption of my nrf51 device. But there will be always some trade-offs.