there seems to be an overlap problem for rsrp and for rsrq in documentation and code comments

[_rm]

looking at  https://github.com/nrfconnect/sdk-nrf/blob/main/include/modem/lte_lc.h

/**
* RSRP.
*
* * -17: RSRP < -156 dBm
* * -16: -156 ≤ RSRP < -155 dBm
* * ...
* * -3: -143 ≤ RSRP < -142 dBm
* * -2: -142 ≤ RSRP < -141 dBm
* * -1: -141 ≤ RSRP < -140 dBm
* * 0: RSRP < -140 dBm
* * 1: -140 ≤ RSRP < -139 dBm
* * 2: -139 ≤ RSRP < -138 dBm
* * ...
* * 95: -46 ≤ RSRP < -45 dBm
* * 96: -45 ≤ RSRP < -44 dBm
* * 97: -44 ≤ RSRP dBm
* * @ref LTE_LC_CELL_RSRP_INVALID : not known or not detectable
*/
int16_t rsrp;

/**
* RSRQ.
*
* * -30: RSRQ < -34 dB
* * -29: -34 ≤ RSRQ < -33.5 dB
* * ...
* * -2: -20.5 ≤ RSRQ < -20 dB
* * -1: -20 ≤ RSRQ < -19.5 dB
* * 0: RSRQ < -19.5 dB
* * 1: -19.5 ≤ RSRQ < -19 dB
* * 2: -19 ≤ RSRQ < -18.5 dB
* * ...
* * 32: -4 ≤ RSRQ < -3.5 dB
* * 33: -3.5 ≤ RSRQ < -3 dB
* * 34: -3 ≤ RSRQ dB
* * 35: -3 ≤ RSRQ < -2.5 dB
* * 36: -2.5 ≤ RSRQ < -2 dB
* * ...
* * 45: 2 ≤ RSRQ < 2.5 dB
* * 46: 2.5 ≤ RSRQ dB



there seems to be an overlap problem for rsrp and for rsrq

* * -1: -141 ≤ RSRP < -140 dBm
* * 0: RSRP < -140 dBm

* * -1: -20 ≤ RSRQ < -19.5 dB
* * 0: RSRQ < -19.5 dB

see also https://docs.nordicsemi.com/bundle/ncs-2.4.3/page/nrf/libraries/modem/lte_lc.html , ... 

what is the actual behaviour?

[helsing]

Hi Richard,

We are looking into this and will get back to you.

[helsing]

The assignment of '0' to RSRP when it's less than -140 dBm and to RSRQ when it's less than -19.5 dB is a design choice made to handle extreme cases where the signal quality is poor. This approach simplifies the handling of extreme cases by grouping them into a single category ('0' in this case), probably making it easier to identify and handle poor signal quality situations in the code.

For RSRP, any value less than -140 dBm is considered bad, indicating a weak signal. Similarly, for RSRQ, any value less than -19.5 dB is considered bad, indicating poor signal quality. By assigning '0' to these ranges, it probably allows for a simplified way to quickly identify these poor signal conditions.

[_rm]

well,  this doesn't answer any part of my question.

a) the overlap 

b) the actual behaviour

[Elfving]

Hello Richard, and sorry about the delay. Håkon is currently a bit busy, so I will handle this case in the meantime. 

I do not know much about this subject myself, but I do see the overlap that you are referring to. I've forwarded your inquiry to the appropriate team, and will let you know once I hear from them.

Regards,

Elfving

[Elfving]

Hello again,

So the overlap is a mistake. It unfortunately likely got that way when we slowly got support for lower and lower values. Thanks for pointing this out to us!

When it comes to the behavior, it is likely a similar problem in the code and not just the documentation. So eg. either the value 0 or -1 is used for RSRP between -141 dBm and -140 dBm. In any case, this does not look like a big issue to me, as you can essentially interpret values 0 and -1 in the same way, right?

Regards,

Elfving