Disconnection because of range

[Swetika]

Hi,

What is min RSSI value at which softdevice decides the disconnection.

Thanks

[Øyvind Karlsen]

Hi,

The SoftDevice does not filter away connections based on low RSSI, in fact RSSI is only set when you receive packages.

The range of a radio system is given by Friis transmission equation, which is dependent on;

• Over-the-air loss
• Receiver antenna
• Transmitter antenna
• Frequency
• Receiver sensitivity
• Transmitter power

It is these factors that decide when the radio system will be disconnected. From the specification we can find that the receiver sensitivity of the nRF51822 is -90dBm for 1Mbps(BLE) activity, this will normally correspond to the lowest RSSI observed. Hopefully this answers your question.

Best regards,

Øyvind

[Petter Myhre]

I just wanted to add that it is the Supervision Timeout in the link layer of the SoftDevice that decides when you have a disconnection. More information can be found in Vol 6, Part B, Section 4.5.2, in the Bluetooth Core specification v4.2.

[Swetika]

thanks for reply. In my application, central connect with any node only when measured RSSI with respect to that node is less and equal to -80dBm. After the connection node gets disconnected with reason code(0x08).According to this link devzone.nordicsemi.com/.../ reason could be out of range. BLE data rate is very less than 1Mbps. Thanks