NR Custom Frequency


This tutorial show you how to define NR band and earfcn which is not defined in 3GPP. Amarisoft SDR can roughly support any frequency between 500Mhz and 6 Ghz without any external Up/Down converter. So you can set any frequency within that range regardless of whether it is defined in 3GPP or not.

If any specific frequency and band is defined in 3GPP, you can just specify the band and earfcn as specified in 3GPP. But if you want to use any other frequency region which are not defined in 3GPP, you can define your own band and earfcn as will be shown in this tutorial.

NOTE :  We provide the same functionality in LTE as well. Refer to this tutorial if you are interested in setting up LTE Custom Frequency.


Table of Contents



Test Setup


I would not use the UE here since commercial UE would not support non-3GPP band and earfcn.

TestSetup Callbox UE 1sdr 01



Key Configuration Parameters


Followings are important configuration parameters for this tutorial. You may click on the items for the descriptions from Amarisoft documents.




I am using gnb-sa-custom-band.cfg which is copied and modified from gnb-sa.cfg  

NR CustomBand Config 01

I added a new TDD flag option as shown below.

NR CustomBand Config 02

Then I defined my own band and earfcn as below.  (NOTE : As you may notice here, there is no arfcn definition here.  In NR custom frequency defintion, you are not allowed to arbitrarily map ARFCN to the frequency. What you can do is define the band and frequency range. ARFCN and Frequency mapping is done by a predefined formula in 3GPP.  This site would be helpful to find figure out frequency and NR earfcn mapping : ). For the meaning of each configuration parameter, refer to this document.

NR CustomBand Config 03

Then I specified an earfcn defined in my own frequecy table. Here I set the band to the custom band that I defined above and pick one of the dl_nr_arfcn and ul_nr_arfcn values that falls into the range of the custom frequency range that I set above.

NR CustomBand Config 04



Run and Check

I cannot provide any test result with commercial UE since commercial UE would not support the custom band.

Just run the LTE service and go to enb screen mode. You can confirm that the band and frequency from the default print out from (enb) screen. If you run [cell phy] command, you can confirm the ARFCN configuration as well.

NR CustomBand Test 1 Run 01

Same as in the default print out of (enb) screen, you can check the frequency with rf_info command.

NR CustomBand Test 1 Run 02

Lastly you can confirm that the band you defined is broadcast in SIB1 message as shown below.  Confirm that frequencyBandIndictorNR and subcarrierSpacing in SIB1 is set to the value as you set in your configuration file.

NR CustomBand Test 1 Run 03