UE Capability Enquiry

 

This tutorial show how Amari Callbox configures items in UE Capabiility Enquiry message by default and how we can add additional enquiry items in the message. UE capability Enquiry/UE capability Information is a signaling mechanism by which UE inform RAN (Radio Access Network) about its RRC capability.  During the initial attach procedure, there are several steps in which UE and Network exchange its capability so that they can setup a proper data pipes that can be supported by both of them. Following is overall procedure of this capability information exchange mechanism.

Step 1 : SIB <-- Basic Network RRC Capability

Step 2 : Attach Request <-- UE NAS Capability

Step 3 : UE Capability Enquiry

Step 4 : UE Capability Information <-- UE RRC Capability

Step 5 : AttachAccept <-- Basic Network NAS Capability

NOTE : For most of Protocol Test equipment, the equipment just exchange signaling message and does not analyze the details of the contents of the message which is different from live network operation. Amarisoft mechnism is much more like live network operation. It analyze the contents of the capability information and apply the configuration differently depending on the contents of the message.

NOTE : If you try some test (apply some configuration) and found it not working as expected, I would suggest you first to check about these capability message and see if UE informs all the details of the capability required for the intended feature.

 

 

Table of Contents

• UE Capability Enquiry
• Test Setup
• Key Configuration Parameters
• Test 1 :  UE Capability Enquiries in default configuraton
• Configuration
• Run and Check in the log
• Test 2 :  UE Capability Enquiries  with Additional Enquiries
• Configuration
• Run and Check in the log
• Test 3 :  UE Capability Enquiries  with All Additional Enquiries (as of 20250211)
• Configuration
• Run and Check in the log

 

 

Test Setup

Test setup for this tutorial is as shown below.  

• SIM Card used in this tutorial is the one delivered with the system as it is.
• If you want to change the configuration, The tutorial Configuration Guide would help

 

Key Configuration Parameters

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

• ue_cap_rat_type
• requested_freq_bands_nr
• requested_eutra_freq_bands
• requested_eutra_max_ccs_dl
• requested_eutra_max_ccs_ul
• request_reduced_format
• request_eutra_reduced_int_non_cont_comb
• mr_dc_request_nr_dc
• rrc_ul_segmentation_support
• single_ue_cap_enquiry
• srs_switching_time_request
• uplink_tx_switch_request
• ue_assistance_information
• overheating_assistance
• prohibit_timer
• max_bw_preference
• prohibit_timer
• max_cc_preference
• prohibit_timer
• max_mimo_layer_preference
• prohibit_timer
• release_preference
• prohibit_timer
• delay_timer
• rrm_meas_relaxation_reporting
• s_search_delta_p_stationary
• t_search_delta_p_stationary

 

Test 1 :  UE Capability Enquiries in default configuraton

This test is just to show how the default configuration of UE Capability Enquiries that is sent by Amarisoft Callbox. This test is mainly for information purpose and setting the baseline. From this baseline, how to add specific user defined configurations will be shown in other test cases.

 

Configuration

In this test, I am using gnb-sa.cfg (NR SA Default Configuration) without any modification just to show how the default configuration sets UE Capability Enquiry message.

 

Run and Check in the log

As shown below, default configuation creates UE capability Enquiry message based on the cell configuration in the configuration file. (NOTE : capabilityRequestFilter IE may or may not be configured depending on the release of the callbox software).

 

 

Test 2 :  UE Capability Enquiries  with Additional Enquiries

This test is an example of adding a user defined configuration in UE Capability Enquiries message. The simplest and the most frequently used configuration would be to specify specific bands in the message. In this test, I will show how to specify specific NR bands in the message.

 

Configuration

In this test, I am using gnb-sa-uecap.cfg which is copied and modified from gnb-sa.cfg

Following is the parameter that I added to gnb-sa-uecap.cfg within nr_cell_list: [  ]. For adding the specific NR bands, you just need to specify the 'rat' type and bands in requested_freq_bands_nr: [  ] configuration.

 

Run and Check in the log

Run the test and check UE capability enquiry message in the log. You can confirm that all the band you specified in the configuration file is added to ueCapabilityEnquiry message.  You can see that the specified frequencies are configured in frequencyBandListFilter in capabilityRequestFilter IE (Information Element).

You can check the details of UE capability from UE capability Information message for each band.  If you go down to supportedBandListNR of rf-Parameters, you can find the details of the configurations for specific bands. Make it sure that you don't find any band configuration out of the list that you specified in the configuration file.

One of the important parameters I want to suggest you to check is about channel bandwidth configuration for each band. I saw many issues coming from the case where a user tries to test with a specific channel bandwidth which is not supported by the UE. (NOTE : Refer to this note for the interpretation of the bitmap)

Amari Callbox software extract band combination information from UE capability Information message and print it out as a separate log print.

You get the UE band combination capability in tabular format as shown below (NOTE : If you are not familiar with how to get this display, check on this note) .

 

Test 3 :  UE Capability Enquiries  with All Additional Enquiries (as of 20250211)

This test is an example of adding a user defined configuration in UE Capability Enquiries message. In this tutorial, I am putting all the paramters that will be enabled in UE capabiltility Enquiry. This is more of showing the syntax and position of those parmeters in cell configuration.

 

Configuration

In this test, I am using gnb-sa-uecap-all.cfg which is copied and modified from gnb-sa.cfg

Following is the parameter that I added to gnb-sa-uecap.cfg within nr_cell_list: [  ]. For adding the specific NR bands, you just need to specify the 'rat' type and bands in requested_freq_bands_nr: [  ] configuration.

I put all the supported UE parameters that will be enabled in UE Capability Enquiry message. I just put all the avaliable parameters as of the release 20250211 and does not have much practical meaning.

 

Run and Check in the log

Run the test and check if the configured parameters are properly included in the UE capability Enquiry message.

In this screenshot, you will see how the parameters requested_freq_bands_nr and srs_switch_time_request are mapped to corresponding IEs in the message.

Sample Log

In this screenshot, you will see how the parameters requested_freq_bands, request_reduce_format, requested_eutra_max_ccs_dl, requested_eutra_max_ccs_ul, request_eutra_reduced_int_non_cont_comb, mr_dc_request_nr_dc, uplink_tx_swich_request, srs_switch_time_request  and rrc_ul_segmentation_support are mapped to corresponding IEs in the message.

Then you can check out the UE capability information from UE. Even if a certain information is requested in UE capability enquiry, the UE may not report the capability information if they are not mandatory and UE does not support the requested feature.