FAILRESTART-2 Failure during the start of an alert that affects all the cells of one or more eNBs

Description

Cell broadcast fails in all the cells of an eNB upon starting the alert.

The affected eNB will not include a Broadcast Completed Area List IE in the WRITE-REPLACE WARNING RESPONSE that it sends to the MME. The MME shall report back to the CBC that broadcast failed in this eNB.

Pre-requisites

• Dispose the conditions for the broadcast to fail in all the cells of one eNB with cells covering the alert area.

TIP

Two possible ways to execute this test case in a real LTE network are:

1. Block / disable cell broadcasting functionality in the eNB by whatever means the eNB vendor provides for this, or
2. Start multiple cell broadcasting messages in parallel so the broacasting resources are congested in all the cells of the eNB.

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. Using a very long message that fills the 15 pages might help to trigger a failure.
   • 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.

Information flow

Result

Verify that:

1. The message sequence completes as define in one of the two options shown in the flow above. Option 1 applies if indication messages are supported and enabled in the MME.

2. For option 1, flow 4.a includes a Broadcast Empty Area List IE that includes the eNB ID of the eNB for which broadcast failed.

   For option 2, flow 4.b includes a Failed Cell List IE with the E-CGIs of all the cells in which the broadcast failed and a Global eNB ID IE with the ID of the eNB that controls the cells in the aforementioned list.

3. The failure event is logged by the CBC.

4. If the CBC is configured to raise an alarm in this case, then an alarm is raised.

5. If the CBE - CBC interface provides the means for conveying information about this type of failures, then the CBC sends this information to the CBE.