FAILRESTART-4 Failure indication for an ongoing alert created by another CBC

Description

The MME reports a Cell broadcast failure in one or more cells for an ongoing alert that was created by a different CBC to the one that receives the failure message.

Pre-requisites

• Two CBCs needed (e.g. in geo-redundancy). Both CBCs have an active connection to the MME.
• Dispose the conditions for the broadcast to fail in one or more cells of the alerting area.

TIP

A possible way to execute this test case in a real LTE network is to block / disable, once the alert is running, cell broadcasting functionality in one or more of the eNBs by whatever means the eNB vendor provides for this.

Steps to execute

1. CBE sends CAP Alert message with:
   • A single info element. I.e. only one message in one language.
   • alertinfo.language.code set to the value of the local language (e.g. sl-SI for Slovenian).
   • alertinfo.instruction.text content of the alert message in local language.
   • Time information that allows the CBC to calculate the repetition period and the number of repetitions.
   • Alert area that is inside the area controlled by a single MME. I.e. only one MME needs to be involved in this test.
2. The CAP alert message in step 1 is processed by CBC-A.
3. Trigger the condition to force the failure in one eNB.

Information flow

Result

Verify that:

1. The message sequence completes as shown in the flow above (note that there might be additional WRITE REPLACE WARNING INDICATION messages after flow 3 if this functionality is enabled).
2. CBC-B ignores the failure message. It may log the message and / or raise an alarm, but it does not need to take any further action.