long range beacon LECODED

[buja]

Hi Team,

we're developing firmware to send long range beacon by using LECODED phy channel. We notice that there is increase in energy consumption during advertising and believe that this is due to the reason that packets are sent in secondary channel in addition to 37,38,39.

We would like to ask the default data rate when using LECODED (LE Coded S= 2 or  LE Coded S= 8). Is there a provision to change data rate in LECODED while advertising ?

[Vidar Berg]

Hi,

Yes, there is some additional overhead when you include advertising on data channels (advertising on the primary channel has to include information about the secondary channel). But more importantly, LE CODED lowers the bitrate so it effectively takes 2x or 8x times longer to transmit data depending on the coding you use (s=2 vs. s=8). This means the radio has to spend more time in TX to transmit the same amount of data.

Are you using the nRF connect SDK (NCS) or the nRF5 SDK? The nRF5 SDK only supports s=8, for NCS I would have to check.

[buja]

Hi Vidar,

We are using SDK 17.1.0

[Vidar Berg]

Then you are left with s=8 I'm afraid.

[buja]

Thank you for your reply.

We thought we would be able to send long range beacons with same energy budget for legacy advertising.

What is the advantage of long range advertising with respect to BLE 5.0, when we can simply increase the TX power of legacy advertising to increase the range ?

[Vidar Berg]

The advantage may be a lower radio TX current while a disadvantage is that you will need an observer that supports scanning on CODED phy. 

Note that our online power profiler (https://devzone.nordicsemi.com/nordic/power/w/opp ) allows you to estimate current consumption for CODED PHY if you select the nRF52840 and connection. It might be helpful to visualize the difference.

Edit: fixed link to the online power profiler.

[buja]

Hi Vidar, Thank you for your reply. But the link doesnt work

Vidar Berg said:

The advantage may be a lower radio TX current

I understand that the peak current will be less. But don't you think, on average, current consumption will be same in both situations ? Because, for LECODED the radio has to be in ON state for more time than in Legacy. 

[Vidar Berg]

Hi,

Yes, I would expect the average current to be about the same for both scenarios for the reason you mentioned.