START-11 Broadcast Failure in several eNBs.

Description

Check that the CBC handles correctly the reception of Broadcast Empty Area List IE in indication messages. This IE contains a list of eNB IDs with the eNBs that have not confirmed active broadcast to the MME.

Correct handling of this case is implementation specific. In general, the CBC should, at least, log this event. It can also generate an alarm towards the fault management (FM) O&M system (e.g. SNMP trap) and even report to the CBE.

TIP

The left-most bits of the Cell ID within an ECGI contain the eNB ID. I.e. the CBC can use the ENB ID to resolve which cells have failed to broadcast the alert. If supported by the CBE - CBC interface, the CBC can translate this cell information into a geographic area and report the failure to the CBE.

Pre-requisites

• Force several eNB in the *Warning Area List" IE of flow 2 to not include the Broadcast Completed Area List IE in the WRITE-REPLACE-WARNING Response to the MME.

Possible ways to meet this pre-requisite are:

• If possible, block CB in some of the eNBs for the alert level used in this test.
• change manually, in the cell database of the CBC, the non eNB ID bits of the CID part of all the EGCIs of some eNBs, or
• import this same incorrect information into the cell database of the CBC, or

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 with several cells.

Information flow

Result

Verify that:

1. The CBC sends one WRITE-REPLACE WARNING REQUEST to the MMEs that control eNBs that covers the alert area. Presence of parameters in this message shall be as shown in the following table:

   Information Element	Included	Value
   Message Identifier	Yes	Matching alert level and language
   Serial Number	Yes
   List of TAIs	Yes	one or more TAIs that cover the alert area
   Warning Area List	Yes	List of cells that cover the alert area
   Repetition Period	Yes	According to the timing requested in flow 1
   Extended Repetition Period	No
   Number of Broadcast Requested	Yes	According to the timing requested in flow 1
   Warning Type	No
   Warning Security Information	No
   Data Coding Scheme	Yes	Set for the language selected according to 3GPP TS 23.038
   Warning Message Contents	Yes	Alert message encoded according to the value of DCS above
   Concurrent Warning Message Indicator	Yes	true
   Send Write-Replace-Warning-Indication	Yes	true
   Global eNB ID	No

2. Each MME that receives flow 2 responds with a WRITE-REPLACE WARNING RESPONSE message with content according to the following table:

   Information Element	Included	Value
   Message Identifier	Yes	Same as in flow 2
   Serial Number	Yes	Same as in flow 2
   Cause	Yes	Set to value Message accepted
   Criticality Diagnostics	No
   Unknown Tracking Area List	No

3. Each MME that receives flow 2 sends one or more WRITE-REPLACE WARNING INDICATION messages with content according to the following table:

   Information Element	Included	Value
   Message Identifier	Yes	Same as in flow 2
   Serial Number	Yes	Same as in flow 2
   Broadcast Scheduled Area List	Yes	List of cells for which broadcast is active
   Broadcast Empty Area List	Yes	List with the eNB ID for which broadcast failed

Broadcast Empty Area List IEs shall only be reported by MMEs that control eNBs in which the alert fails to broadcast in all their cells.

4. Broadcast is active in all the cells of eNBs that have not reported a failure to broadcast.
5. Proper event information is logged including the eNB IDs that have reported the failure.
6. If applicable, the CBC raises an alarm in the FM system at the O&M centre.
7. Report to the CBE, if the CBE-CBC interface supports it.