How to Interpret RSRP Values on RMU500-EK?

IoT Modules 5G Module
1

I have a question regarding the command to report RSRP. When I execute the command “AT+RSRP”, I receive the RSRP of the current service network. This RSRP value is measured by the UE (RMU500-EK) and also reported to the network. On the network side, I can also check the reported RSRP value from the UE using a communication tester that generates the network. This ensures I can read the RSRP value measured by the UE on both the UE side and the network side, and these values should be the same. However, I notice a discrepancy of 15 dBm between them.

I verified this with other UEs, and in those cases, the RSRP values reported on both the UE side and the network side are identical. Therefore, I believe I might be misinterpreting the value read from the UE.

According to the UE documentation, the RSRP value range should be between -140 and -44 dBm. Referring to 3GPP TS 38.133, the table for SS-RSRP and CSI-RSRP measurement report mapping shows L3-SS-RSRP (ranging from -156 to -31) and L1-SS-RSRP/CSI-RSRP (ranging from -140 to -44 dBm). The L1-SS-RSRP/CSI-RSRP defined in the 3GPP standard matches the values reported by the UE.

My question is: Which RSRP value do I read with the command “AT+RSRP”? At first glance, based on the standard and the UE documentation, I would assume it is L1 SS-RSRP/CSI-RSRP. However, considering my measurement results and comparison with other UEs, it seems that an adjustment of 15 dBm is necessary to align the values read from the UE with the correct results.

2

Dear @Laura_de_baets
Which module did you use? And share the current firmware.
I only found AT+QRSRP.

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You can also use AT+QENG=“servingcell” to check RSRP.

3

Dear @silvia
Thank you for answering!
The module I use is the RM520NGLAA-M20-SGASA. I haven’t changed the firmware, so it still has the original firmware that was on it when I bought it.
I also found in the documentation AT+QRSRP. And I’m wondering wich RSRP value do I read with that command?
Best Regards,
Laura

4

Dear @Laura_de_baets
Actually, we don’t use AT+RSRP, you also didn’t see this command in our document.
It is recommanded to use AT+QRSRP.

5

Hi @silvia
I apologize for the confusion in my previous message. The command AT+RSRP does not exist; I made a typo. I meant to refer to the command AT+QRSRP. Could you please tell me which RSRP value I can read using the AT+QRSRP command?

6

Dear @Laura_de_baets
Sorry, I didn’t get your point.
This AT command will get RSRP values for four antannes.

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7

Dear @silvia,
Is it maybe possible that there is a bias of 15 dBm to this value added by the board?
When I measure with an other UE, I got a difference of 15 dBm between the other UE and this board.
Best Regards,
Laura

8

Dear @Laura_de_baets
Did all the parameter have 15 dBm with other board?
For different combinations, it will use different combinations with antenna.

9

Dear @silvia
Can it be if I dissable antenna 2,3 and 4. So that only antenna 1 is used, that this difference is maybe solved?
Is there a way to disable antennas with commands?
Kind Regards,
Laura

10

Dear @Laura_de_baets
If only have antenna, maybe you can’t register on network. I didn’t test like this.

We don’t have AT commands to disable antennas.