RUTX50 carrier aggregation on Croatian telecom (HT)


I use the RUTX50 on the network of the Croatian telecom (deutsche telecom group) in combination with 2x2 MIMO external directional antennas.

The base station I am connecting to supports aggregations:
B1(15MHz)+B3(20MHz)+B3(10Mhz)+B20(15MHz)+B28(10Mhz) on the same eNB ID, 4x2 MIMO

Other devices measure speeds of 350+ Mbps, and the RUTX50 only connects to two aggregations, mostly B1+B3, and speeds reach 200-250 Mbps.

When I lock the main cell to B3(10Mhz), then it works 4CA (B1+B3+B3+B20/28 or B1+B3+B20+B28) but the speeds are still up to 200 Mbps, even lower than on 2CA.
5CA in DL never worked.

I noticed that the modem does not know how to aggregate upload bands when the main cell is B3 (10Mhz), the upload speed goes up to a maximum of 45 Mbps.

The technician from Croatian Telecom says that with this modem I should have speeds of at least 400 Mbps at the base station I connect to if 4CA or 5CA is used.

I also noticed in the webUI under Status > Network that it never says more than 3CA even though gsmctl -A ‘AT+QCAINFO’ shows that the modem is using 4CA.

Fw version: RUTX_R_00.07.04.5
Internal modem firmware version: RG501QEUAAR12A08M4G_04.200.04.200

Are you able to check this and adjust the modem for correct aggregation of bands on Croatian telecom networks?

Thank you


Carrier Aggregation capabilities are limited by the internal modem chipset, thus it is not possible to change them via an update.
However, I’ve noticed that you have locked onto the B3 cell which supports 10MHz bandwidth, while the B3 cell acting as a secondary supports 20MHz. Could you try locking onto a cell with EARFCN of 1501 and check if that makes any difference? Primary cell can usually impact the overall network performance and stability greatly.
As for only 3 bands showing up in the WebUI, this is a know visualization issue, and it will be addressed with the 7.5 release.
Just in case you were referring to band lock, and not cell lock, here is a short manual for band locking on RUTX50: RUTX50 - Locking 5G-NSA CA bands manually - #4 by Daumantas

Best regards,

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