5G Signal properties

[Reinhard Speyerer]

On Tue, Jun 09, 2020 at 08:50:10AM +1000, Nick wrote:
> Hi Walter,
> 
> I???m seeing a similar issue with my RM500Q-GL.  Can you please post the output of: qmicli -p -d /dev/cdc-wdm0 --dms-get-band-capabilities
> 
> Mine below for your reference.  You would note on mine, after the Extended LTE bands, where we would expect to see the 5GNR band TLV response, that it is absent. (Thanks to Sebastian for showing me that.)  However, I am currently not attached to a 5G network, nevertheless, when I attempted this test while attached to a 5G network, I had the same result.
> 
> 
> Best,
> Nick
> 
> 
> When I was on 5G
> ---------------
> AT+QENG="Servingcell"
> +QENG: "servingcell","NOCONN???
> +QENG: "LTE","FDD",505,01,8B45502,349,1300,3,5,5,700B,-83,-10,-53,20,0,-150,-
> +QENG: ???NR5G-NSA???,505,01,45,-32768,-32768,-32768 (note the negative values for signal, equivalent to 0b1000000000000000)
> --------------
> Responses for AT+QENG 5GNR: Access Tech, MCC, MNC, PCID, RSRP, SINR, RSRQ
> 

Hi Nick,

same over here when using a test network in 5G NSA mode:

at+qeng="servingcell"
+QENG: "servingcell","NOCONN"
+QENG: "LTE","FDD",1,01,1A2D001,1,300,1,3,3,1,-87,-3,-67,23,255,-32768,52
+QENG:"NR5G-NSA",1,01,500,-32768,-32768,-32768

OK

NASGetSignalInfo output for 5G NSA (from another test, still with the RG500Q):
+OK NASGetSignalInfo 02040000000000140600bffaa8ffb600170400008000801802000080

My assumption is that RSRP, SINR and RSRQ above would only be defined for
5G SA mode as can be seen from the qmicli -v --nas-get-signal-info output here
https://gitlab.freedesktop.org/mobile-broadband/libqmi/-/issues/32 .

I tried to stay out of the "guessing 5G QMI TLVs" business but since we
may never see a GobiAPI 2020 update here it goes anyway:
TLV 0x17 = RSRP and SINR (scaled by 10 like for LTE(?)), TLV 0x18 = RSRQ.

A TLV that looks a little bit easier to guess due to its unusual size:
NASGetSystemInfo TLV 0x50 = 5GS TAC from TS 24.501 section 9.11.3.8.

Regards,
Reinhard