START-9 Unknown TAI in List of TAIs IE that contains multiple TAIs.

Description

Check that the CBC handles correctly unknown TAIs reported by MMEs.

Most often the cause of this condition is misconfiguration in the CBC that should be fixed by operations personnel.

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).

Pre-requisites

• Associate some radio cells of the alert area to invalid TAIs. The alert area should have cells in one or more valid TAIs and cells in on or more invalid TAIs.

Possible ways to force this pre-requisite are:

• change manually the TAI data for some cells in the cell database of the CBC, or
• import incorrect information into the cell database of the CBC.

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 cells in two or more TAIs.

Information flow

Result

Verify that:

1. The CBC sends one WRITE-REPLACE WARNING REQUEST to each of the MMEs that control eNBs in the TAs that cover 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	Two or more TAIs (at least one unknown to the MME)
   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	Yes	unknown TAIs from the List of TAIs in flow 2

3. Each MME that received flow 2 and controls eNBs with cells in the Warning Area List in flow 2 that are inside valid TAIs from the List of TAIs in 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	May	List of cells for which broadcast failed

4. Broadcast is active only in cells in the Warning Area List in flow 2 that are inside valid TAIs from the List of TAIs in flow 2.

5. Event is logged for invalid TAIs.

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.