NRF52840 power consumption under different RSSI

[Domneck]

Hi All,

I'm new to this wireless field. Is there any impact on power consumption based on RSSI level.

As I understand due bad RSSI there will be retries in communication, other than this are there any cases?

Thanks in advance.

Regards,

Reedomneck`

[Einar Thorsrud]

Hi Reedomneck,

There is no practical difference in the current consumption required to receive a packet regardless of the RSSI. So any additional current consumption will come from retransmissions.

Einar

[Domneck]

Thanks for the info. I’m performing power profiling for the poor RSSI levels and I see some extra peaks. I’ve configured tx power level as 0dbm and for this as expected I’m seeing peaks up to 3-4mA but I’m also seeing some peaks upto 1.5mA. These 1.5mA peaks are not seen every time. When these peaks are seen the packet exchange duration is increasing for same amount of data.

[Einar Thorsrud]

Hi,

If you see increased packet exchange duration without more data sometimes during low RSSI conditions, that matches perfectly with retransmissions. (You can confirm that by using a sniffer if you like). I am not able to get 1.5 mA to match what I would expect, as the radio in both Tx and Rx would be significantly higher, but perhaps there is something about how you are measuring? Perhaps you can share a plot?

[Domneck]

Hi,

I'm attaching the plots here.

One is captured for 90 rssi and another one is 40 rssi.

RSSI 40: 

RSSI 90 

[Einar Thorsrud]

The area you have marked with "link layer retries" are not that. The current consumption is too low. I cannot say what happens there based on the current consumption pattern, but it is something else.