Issue in connecting QUECTEL RM502Q-AE to LTE network

[IFTEKHAR HASAN]

We have a modal AI Voxl2 with QUECTEL RM502Q-AE and I am trying to connect it to our LTE network . ON QUECTEL RM502Q-AE datasheet, it shows support for both 5G & 4G and we want drone to connect to LTE B4 which is supported. We used below AT command to set LTE only mode and configured custom APN for quectel modem from the selection using voxl-configure-modem

echo -ne "AT+QNWPREFCFG="mode_pref",LTE\r" | busybox microcom /dev/ttyUSB2

On the network side, I didn't notice any LTE connection attempt. Is this the correct procedure to configure modem to LTE only for QUECTEL RM502Q-AE?

Another question is that in your forum, it shows LTE connectivity through V2 add on board . Does it mean QUECTEL RM502Q-AE doesn't support LTE ?

[Vinny]

Hi @IFTEKHAR-HASAN
I am from HW, so I cannot comment on the SW issues you have, but I can clarify the notations we use.
When we specify a modem as being "4G" or "5G", that is it's highest rated radio link connection.
All 5G radios can support many 4G modes (and 3G modes) up to their specifications as shown in the module specs.
https://www.quectel.com/product/5g-rm50xq-series

All 4G modems also support many 3G bands.
https://www.sierrawireless.com/iot-modules/smart-modules/

Hope this helps explain that for you.

[IFTEKHAR HASAN]

@Vinny thank you Vinny. I appreciate your response and it does clarify the doubt.

[IFTEKHAR HASAN]

I looked at the data set and it does support LTE B4 . I do see the device is getting an IP address on LTE B4 but not successful in setting up LTE session ( no bearer setup) and instead tries to measure 5G network for 5G NSA connectivity. We don't want Quectel modem to search for any 5G network and our test setup requires 4G network . I tried to set mode to LTE only using below AT command from the adb shell window but the modem still tries to connect to 5G network and not completing LTE session setup( no bearer setup happened) .

echo -ne "AT+QNWPREFCFG="mode_pref",LTE\r" | busybox microcom /dev/ttyUSB2

How can I make the quectel 502Q-AE modem to only connect to LTE

[Eric Katzfey]

@IFTEKHAR-HASAN I think you'll have to try to find that in the Quectel documentation. I would imagine that it is some AT command or sequence of AT commands that would do that for you.

[Eric Katzfey]

@IFTEKHAR-HASAN Take a look at this script: https://gitlab.com/voxl-public/voxl-sdk/utilities/voxl-modem/-/blob/master/scripts/only-band-3-lte.sh. This was used to force a Sierra Wireless cellular modem into Band 3 LTE only mode.

[tom]

@IFTEKHAR-HASAN I would also try upgrading to a newer version of voxl-modem (1.0.4), grabbing from here: http://voxl-packages.modalai.com/dists/qrb5165/staging/binary-arm64/voxl-modem_1.0.4_arm64.deb

There have been some updates to the quectel-CM source since our last platform release

[IFTEKHAR HASAN]

@tom thank you for your response. I think I have newer image

system-image: 1.4.1-M0054-14.1a-perf
kernel: #1 SMP PREEMPT Thu Oct 13 17:48:16 UTC 2022 4.19.125

hw version: M0054

voxl-suite: 0.9.4

[tom]

@IFTEKHAR-HASAN It appears as though you're on SDK 0.9. Since then we've released SDK 0.9.5.

However, I'd recommend loading an even newer voxl-modem package from here:
http://voxl-packages.modalai.com/dists/qrb5165/staging/binary-arm64/voxl-modem_1.0.4_arm64.deb

This one hasn't made it into an official SDK release yet but contains the quectel-CM updates I mentioned earlier.