nRF9160 max transmit power

[Frikkie Badenhorst]

Hi there, 

We want to compare the power profile of the nRF9160 with a different device, but for this we want to ensure that both devices are transmitting at the exact same transmit power 23dBm. We then configure the base station to force the devices to transmit at max power.

However, the nRF9160 does not seem to transmit at max power on its own, only when we send the AT+CFUN=1 command to both devices at the exact same time, we see the nRF9160 also transmitting at max power. Attached is a power profile of the nRF9160, indicating that it only transmits at max power when the other device starts transmitting. (The arrow indicates when the other device starts transmitting)

Is there anything from the nRF9160 side that can be causing this? What AT commands can we use to see the max allowed power of the device? What AT commands can we use to see the actual transmit power of the device?

We are using the LTE Serial Monitor app to set up our own test environment.

[Frikkie Badenhorst]

We have managed to fix this issue from the base station side. However I do still have the following questions:

1) What AT commands can we use to see/edit the max allowed power of the device?

2) What AT commands can we use to see the actual transmit power of the device?

 

[Frikkie Badenhorst]

Hi,

Can someone please assist with this issue as soon as possible as it is quite urgent?

I have come across the  AT%CONEVAL AT command, which I believe can be used to see the actual transmit power of the UE. Unfortunately we are not able to use this command, as we are getting the "ERROR" response when attempting to use this every time.

[BjoernS]

Hi,

the AT%CONEVAL AT command is only available if you are using the modem firmware version 1.3.0 and above. Have you checked if you are using this firmware version on your nRF9160?

[Frikkie Badenhorst]

Hi,

Looks like v1.3.0 came out recently and we were not aware of it. We have upgraded the firmware and are successfully able to test the AT%CONEVAL command to see the actual transmit power.

Thus, question 1) is the only question outstanding: 

Frikkie Badenhorst said:

1) What AT commands can we use to see/edit the max allowed power of the device?

For example is it possible to set the maximum allowed tx power from 23 to 14dBm if we for instance know that the device is close to a base station?

[BjoernS]

As far as I know that is not possible since the base station is making the decision what TX power the UE has to use.

[Frikkie Badenhorst]

Hi Bjoern, thanks. Would you then please assist in your understanding/knowledge of devices with different power classes.

Lets say for example we have a power class 3 device (max transmit power of 23dBM) and a power class 6 device (max 14dBm). How does the base station then know which device has a max power of 14 and 23 dBM respectively? Is this included in an uplink message somewhere? Or does the base station not know this, and if the base station for example tells the 14dBm device to be "set" to 23dBM, it will just force itself to 14dBm since that is its max transmit power?

We have seen some modules from different manufacturers that supports AT commands in which you can set the max transmit power of the device and was thus wondering if Nordic also allows this (thus increasing the power class of the device)?

I hope the questions are clear - if not please let me know as it is important for us to understand this.