Bluetooth 5 Long range

[klin]

Hi, to use the bluetooth 5 long range feature, do both the transmitter and receiver need to be configured to in this mode to work? Do you have any example AES 128 that I can try on the nRF52840 dev board?

Thank you

[AmbystomaLabs]

There are two methods of long range with Bluetooth 5. One way Bluetooth 5 provides for longer range is by supporting up to 20dBm power output for BLE.

If you are referring to the higher power side of Bluetooth 5, then no you do not need both devices be bluetooth 5 compliant. However you should keep in mind that if only one device is higher power then you will have a lopsided link budget with only one device effectively getting its data through.

The second part of bluetooth 5 long range is a coded phy. Likely this is what you are referring to. With the coded phy the device has an effective 125kbit/sec phy even though the radio is running at 1megsym/sec. This is done by transmitting 8 bits for every one and the result is analogous to PBCC (packet binary convolutional coding) and spread spectrum. The extra bits allow the receiver to decode data even when then signal strength is lower.

The improvement in sensitivity that can be expected is 10 log(8) or 9dB. Additionally, since the phy is coded in a particular manner the receiver performs forward error correction against the decoded data for a total effective improvement in sensitivity of 12dB. In this manner bluetooth 5 in line of sight applications can be expected to have 4 times the range of bluetooth 4.x.

When using a coded phy in bluetooth 5, YES both devices need to support this aspect of bluetooth 5. Otherwise, the data cannot be encoded by the transmitter and cannot be decoded by the receiver.

The AES128 question just refers to the link security and has nothing to do with long range. I don't believe anything has changed there. BLE 4.x supported AES128. I don't have any AES128 examples handy. Maybe someone else will chime in with some.

[klin]

Thank you for clarifying this :)