LTE Dedicated EPS Bearer

This tutorial shows how to trigger a Dedicated EPS Bearer with Amari Callbox + Amari UEsim and Amari Callbox + Commerical UE. The main purpose of this tutorial are as follows :

• How to configure Dedicated EPS parameters in Amarisoft Callbox.
• How to apply QCI defined in 23.203 Table 6.1.7: Standardized QCI characteristics to Amarisoft Callbox Parameters

In LTE, two types of EPS bearer are defined.

• Default EPS bearer : A common configuration being applied to all the traffics in a IP pipe. This common pipe can have multiple flows in it.  Each Default EPS bearer has its own IP and APN assigned to it.
• Dedicated EPS bearer : A specific configuration being applied to a specific flows of the IP pipe assigned by Default EPS bearer. Dedicated EPS bearer does not have its own IP and it should be linked to a specific Default EPS bearer.

In LTE, at least one Default EPS bearer should be established during the initial attach process and additional default EPS bearer or dedicated bearer can be added afterwards.

Table of Contents

• LTE Dedicated EPS Bearer
• Test Setup
• Key Configuration Parameters
• Test 1 : Amari Callbox + UEsim, Dedicated Bearer Triggered by UEsim for QCI 6 (Non-GBR)
• Configuration
• Perform the Test
• Log Analysis
• Test 2 : Amari Callbox + UEsim, Dedicated Bearer Triggered by UEsim for QCI 4 (GBR)
• Configuration
• Perform the Test
• Log Analysis
• Test 3 : Amari Callbox + Commerical UE, Dedicated Bearer Triggered by UE
• RRC / NAS Signaling
• Activate dedicated EPS bearer context request

Test Setup

Test setup for this tutorial is as shown below.  (NOTE : This setup is for Amari Callbox + Amari UEsim.  For Amari Callbox + Commercial UE case, refer to Test 3).

• 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.

• erabs : In this link, you will get the description for all the items listed below.
• qci
• priority_level
• pre_emption_capability
• pre_emption_vulnerability

Test 1 : Amari Callbox + UEsim, Dedicated Bearer Triggered by UEsim for QCI 6 (Non-GBR)

This test shows an example of establishing Dedicated EPS Bearer triggered by UE (Amarisoft UEsim in this case). In this test, UE request to setup a dedicated EPS bearer for QCI 6 (Non-GBR). The main purpose of this test is to show how to trigger Dedicated Bearer for a Non-GBR.

Configuration

I used the default LTE configuration (ue.default.cfg) without any change on UE Sim.

I used the default eNB configuration (enb.default.cfg) without any change on Callbox

I used mme-ims-ue-initiated-ded-bearer-qci6.cfg which is copied from mme-ims.cfg and modified.

In mme-ims-ue-initiated-ded-bearer-qci6.cfg, you see ue_db-ims.cfg is used.

In mme-ims-ue-initiated-ded-bearer-qci6.cfg add the following configuration. In the configuration, setup_type is set to "ue_initiated" which means that this bearer setup should be triggered by UE. qci is set to 6 which is a Non-GBR bearer.

In ue_db-ims.cfg on Callbox, I used following USIM parameters. This is a default USIM setting of Amarisoft test USIM. If you are using a different test USIM, change these parameters (sim_algo, imsi, amf, sqn, K) according to the USIM.

In ue.default.cfg on UEsim, I used following USIM parameters. The imsi, K on UEsim should match the ue_db settings in Callbox setting.

Perform the Test

Start trace logging on Callbox

Power on UE on UEsim

Then you see following traces on Callbox and confirm UE gets attached

When UE is in connection with a cell, you can get the information on the connected cell using 'cells' command on UEsim

When UE is in connection with a cell, you can get the information on the connected UE using 'ue' command in (ue) screen on UESim (NOTE : pay special attention to UE_ID shown here because this UE_ID should be specified in the remote API command at later step).

When UE is in connection with a cell, you can get the information on the connected UE in NAS layer using 'ue' command in (mme) screen

In the directory : /root/ue/doc on UEsim, run following command

./ws.js ue '{"message":"ue_activate_dedicated_bearer","ue_id":1,"def_bearer_id":5,"qci":6,"filters":[{ "direction":"both","id":1,"precedence":1,"components":[{"ipv4_remote_addr": "192.168.2.1","type_of_service":"ipv4","mask":"255.255.255.0"}]}]}'

(NOTE : Make it sure that you set the right value for "ue_id". Set the "qci" to the value set in the configuration file)

If UE is in proper call status and the above command is properly processed, you would get the response as follows.

Log Analysis

Following is snapshots from UEsim log.

Before you send RemoteAPI command, I would recommend to check the default EPS bearer ID you want to link the dedicated bearer you will create. You can check out the EPS Bearer Identity in Attach Accept message in this case.

After you send the RemoteAPI, you see a sequence of following messages. In "Bearer resource allocation request" message, you can confirm that "Linked EPS bearer identity" is set to 5 and QCI is set to 6.

Then RRC Connection Reconfiguration is triggered for setting 'radioResourceConfigDedicated'.

Then 'Activate dedicated EPS bearer context request' is triggered with 'Linked EPS bearer identity = 5' and 'QCI = 6' as configured in the configuration file and remoteAPI.

The dedicated EPS bearer setup gets completed by 'Activate dedicated EPS bearer context accept' message from UE.

Test 2 : Amari Callbox + UEsim, Dedicated Bearer Triggered by UEsim for QCI 4 (GBR)

This test shows an example of establishing Dedicated EPS Bearer triggered by UE (Amarisoft UEsim in this case). In this test, UE request to setup a dedicated EPS bearer for QCI 4 (GBR). The main purpose of this test is to show how to trigger Dedicated Bearer for a GBR.

Configuration

All the configurations are same as Test 1 Configuration except the followings.

I used mme-ims-ue-initiated-def-bearer-qci4.cfg which is copied and modified from mme-ims.cfg

In mme-ims-ue-initiated-def-bearer-qci4.cfg, add following configurations.  In the configuration, setup_type is set to "ue_initiated" which means that this bearer setup should be triggered by UE. qci is set to 4 which is a GBR bearer. Key point for this is the configuration in gbr: {  }. You would also notice that the value of pre_emption_capability and pre_emption_vulnuerability are set to "may_trigger_pre_emption" and "pre_emptable" respectively.

Perform the Test

Test Procedure is same as in Test 1 Procedure except the followings (the last step).

In the directory : /root/ue/doc on UEsim, run following command

./ws.js ue '{"message":"ue_activate_dedicated_bearer","ue_id":1,"def_bearer_id":5,"qci":4,"gbr": {"maximum_bitrate_dl": 49000, "maximum_bitrate_ul":49000,"guaranteed_bitrate_dl":49000,"guaranteed_bitrate_ul":49000},"filters":[{ "direction":"both","id":1,"precedence":1,"components":[{"ipv4_remote_addr": "192.168.2.1","type_of_service":"ipv4","mask":"255.255.255.0"}]}]}'

(NOTE : Make it sure that you set the right value for "ue_id". Set the "qci" to the value set in the configuration file)

If UE is in proper call status and the above command is properly processed, you would get the response as follows.

Log Analysis

Following is snapshots from UEsim log.

Before you send RemoteAPI command, I would recommend to check the default EPS bearer ID you want to link the dedicated bearer you will create.

After you send the RemoteAPI, you see a sequence of following messages.  In "Bearer resource allocation request" message, you can confirm that "Linked EPS bearer identity" is set to 5 and QCI is set to 4.

Then RRC Connection Reconfiguration is triggered for setting 'radioResourceConfigDedicated'.

Then 'Activate dedicated EPS bearer context request' is triggered with 'Linked EPS bearer identity = 5' and 'QCI = 4' as configured in the configuration file and remoteAPI.

The dedicated EPS bearer setup gets completed by 'Activate dedicated EPS bearer context accept' message from UE.

Test 3 : Amari Callbox + Commerical UE, Dedicated Bearer Triggered by UE

I don't have any separate tutorial for this case because you can see this case in  the tutorial VoLTE

RRC / NAS Signaling

Activate dedicated EPS bearer context request

: This is the Activate dedicated EPS bearer context request message sent by  LTE Core to activate the dedicated EPS Bearer (NOTE : You would see some IEs that has a specific assigned vale here, but consider it as just an example value. Those values should vary depending on test requirement)

Protocol discriminator = 0x7 (EPS Mobility Management)

Security header = 0x2 (Integrity protected and ciphered)

Auth code = 0x34602608

Sequence number = 0x03

Protocol discriminator = 0x2 (EPS Session Management)

EPS bearer identity = 6

Procedure transaction identity = 2

Message type = 0xc5 (Activate dedicated EPS bearer context request)

Linked EPS bearer identity = 5

EPS QoS:

  QCI = 6

Traffic Flow Template:

  TFT operation code = 1 (create new TFT)

  E = 0 (parameters list is not included)

  Number of packet filters = 1

  Packet filter identifier = 1

    Packet filter direction = 3 (bidirectional)

    Packet filter evaluation precedence = 1

    IPv4 remote address = 192.168.2.1 mask 255.255.255.0