LTE Custom Frequency
This tutorial show you how to define LTE 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.
Table of Contents
- LTE Custom Frequency
Test Setup
I would not use the UE here since commercial UE would not support non-3GPP band and earfcn.
Key Configuration Parameters
Followings are important configuration parameters for this tutorial. You may click on the items for the descriptions from Amarisoft documents.
- custom_freq_band: In this link, you will get the descriptions for all the items listed below.
- band
- dl_earfcn_min
- dl_earfcn_max
- ul_earfcn_min
- ul_earfcn_max
- dl_freq_min
- ul_freq_min
Configuration
I am using enb-custom-band.cfg which is copied and modified from enb.default.cfg
I added a new TDD flag option as shown below. I added an option for custom frequency to TDD option.
Then I defined my own band and earfcn as below. Here dl_freq_min (absolute frequency in Mhz) is mapped to dl_earfcn_min and ul_freq_min is mapped to ul_earfcn_min. The incremental steps are as defined in 3GPP specification.
Then I specified an earfcn defined in my own frequecy table. I specified a customer earfcn to dl_earfcn and ul_earfcn.
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.
Same as in the default print out of (enb) screen, you can check the frequency with rf_info command.
Lastly you can confirm that the band you defined is broadcast in SIB1 message as shown below. Make it sure that freqBandIndicator IE in SIB is set to the custom band that you specified in the configuration file.
