RM502-AE NR5G Cell Locking

[hazarjast]

Hello,
I am working on a project with the RM502Q-AE and have some doubts in regards to NR5G SA cell locking. I know the format to lock NR SA cell is:
AT+QNWLOCK=“common/5g”,[pci],[freq],[scs],[band]

However, since there is no AT+QENG=“neighbourcell” I am unsure which values I need to input here especially regarding [freq] and [scs] for my carrier. In NSA mode I am able to see NR details such as pci and band using “servingcell” output but frequency is output only as ARFCN and scs value is not present at all. For QNWLOCK [freq] do we use ARFCN or actual frequency (ex. “2598.150” for an ARFCN of “519630”)?

If you can provide any guidance or additional document here for scanning/determining my locally available NR SA band info it would be most helpful. Also, can you confirm if “neighbourcell” command functionality will be updated in later firmware to work for NR SA like it does for LTE? Presently I am on RM502QAEAAR11A02M4G. I see there is “AT+QSCAN” but it is warned to not use this when SIM is inserted so not sure if this is a safe command to use or not.

Thank you.

[Peter.Zhu-Q]

Dear Sir,
Please use AT+QNWPREFCFG=“mode_pref”,nr5g to fix 5G mode only, if there are available 5Gnr cell, then the module will register the 5G cell. Thanks!

[snowgum]

@hazarjast

I see there is “AT+QSCAN” but it is warned to not use this when SIM is inserted so not sure if this is a safe command to use or not.

I’ve run AT+QSCAN=2 on my RM500Q-AE with no SIM installed, and got this result:

+QSCAN: “NR5G”,505,03,159130,132,-99,-11,29,0
+QSCAN: “NR5G”,-,-,175450,584,-,-,-,0
+QSCAN: “NR5G”,-,-,637632,584,-,-,-,1

Later I ran it with a SIM installed and a data connection up (in ECM mode), and got this result:

+QSCAN: “NR5G”,505,03,159130,132,-102,-11,26,0
+QSCAN: “NR5G”,505,03,159130,230,-,-,-,0
+QSCAN: “NR5G”,-,-,643680,446,-,-,-,1
+QSCAN: “NR5G”,-,-,175450,584,-,-,-,0
+QSCAN: “NR5G”,-,-,637632,584,-,-,-,1

The SIM is for PLMN 505 01.

The band can be looked up from the ARFCN on this site: https://www.sqimway.com/nr_band.php

For some values, a shortlist of possible bands is given, and local knowledge about what bands a provider uses may be needed.

[hazarjast]

Hi Peter,
Thanks for the quick reply and info. I am already using QNWPREFCFG to set mode preference to NR5G so that I can be sure connection is SA. However, I have both n71 and n41 available in my test area so this is why I am asking about appropriate syntax/input of QNWLOCK for “common/5g”.

Given n71 has the stronger signal being a lower frequency, the modem always connects to this but it has less bandwidth than n41; this is why I want to confirm QNWLOCK input syntax for NRG5 lock so that I can instruct the modem to connect to n41 instead. This is something I already do on the equivalent LTE bands B71/B41 (using QNWLOCK=“common/4g” with mode_pref LTE before I began testing NR SA capabilities).

If you could still confirm that [freq] input for QNWLOCK=“common/5g” is in format of NR-ARFCN (as opposed to frequency in actual Mhz), this would be most helpful.

Thank you again!

[hazarjast]

This is most helpful, thank you! Really appreciate your sharing knowledge and quick reply.

When reading the AT Command Guide for RM5xxQ Series, for QSCAN I did not immediately understand that it output integer 0-3 corresponding to 15-120kHz. This was why I was expecting to see QSCAN output with kHZ integer (ex. ‘+QSCAN: “NR5G”,505,03,159130,132,-99,-11,29,15’ or ‘+QSCAN: “NR5G”,505,03,159130,132,-99,-11,29,60’). Now I understand my mistake

Cheers!

[snowgum]

@hazarjast

Given n71 has the stronger signal being a lower frequency, the modem always connects to this but it has less bandwidth than n41; this is why I want to confirm QNWLOCK input syntax for NRG5 lock so that I can instruct the modem to connect to n41 instead.

I guess you know you can achieve that outcome by bandlocking. You could exclude n71 from the SA band list, exclude everything except n41, or any setting in between.

Example using n1, n3, n7 and n41:

AT+QNWPREFCFG=“nr5g_band”,1:3:7:41

[hazarjast]

Thanks for your reply

Yes, I am aware band locking is another way to similarly achieve this but it does not quite offer the ‘surgical precision’ I like about cell locking.

To explain: I have two towers about equal distance away which broadcast the same bands and unfortunately one has either more congestion or less backhaul (I’m not exactly sure which) but the end result is that my connection is slower when the modem attaches to that tower. Thus, with band locking sometimes I will get the desired band, but attach to the tower which is slower (even though signal itself may be stronger in that moment).

Cell locking in this scenario is preferable which I have done for a long time on LTE cells with Quectel modems. Just starting to play with more 5G now and noticed that QNWLOCK syntax was a bit different so wanted to make sure I understood it fully before using as I already do for LTE.

Cheers, and thanks again!

[Peter.Zhu-Q]

For / parameters, you can use at+qscan to search , then use at+qnwlock to lock the specific 5g cell.Thanks!

[hazarjast]

Thank you. Your screenshot provided confirms that input is NR-ARFCN. This is what I wanted to be sure of

Appreciate your help!