Do reading of RSSI cause any air request to BLE device?

Question

I'm implementing iOS library that reads heart rate sensor data using Bluetooth 4.0 (AKA Bluetooth Smart AKA BLE).

I noticed that RSSI value is being updated only on demand (readRSSI) - otherwise is't always the same.

My doubt is: "Does reading or RSSI cause additional request to the sensor?". My consideration is about power saving of the device.

I suppose my question is generally to BLE, don't think it's iOS-specific...

Any thoughts are appreciated.

Answer 1

readRSSI reports the RSSI being averaged over an active connection. So if you have a connection to your sensor, reading RSSI doesn't cause any additional overhead. Even if you aren't exchanging user data, your BT devices are periodically communicating to keep synchronized with an active connection, and RSSI can be measured from this ongoing communication.

If you are tearing down your connection, then yes, you will have to reconnect to actually measure RSSI.