Disconnection because of range

RE: Disconnection because of range

Swetika — Fri, 12 Jun 2015 04:59:29 GMT

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

RE: Disconnection because of range

Petter Myhre — Thu, 11 Jun 2015 10:51:29 GMT

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.

RE: Disconnection because of range

Øyvind Karlsen — Thu, 11 Jun 2015 10:42:48 GMT

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