START-13 WRITE-REPLACE-WARNING Response not received or delayed. With MME pooling.

Description

Cell sends a request to broadcast an alert to one MME but The MME does either not respond to the CBC or respond too late. The CBC re-sends the request to another MME of the same pool (ie. one that controls the same eNBs).

Pre-requisites

• Define an alert area within the coverage of a single TA.
• There is no ongoing cell broadcast in any of the cells that cover the alert area.
• The message is in the local language.
• Alert timing defined so it is easy to verify that the value of the parameters Number of broadcast and broadcast period that the CBC sends to the MME.
• The SCTP association between the CBC and the MME is working correctly. The MME has no problem to receive messages from the CBC and respond to them.
• If it is possible, configure the non-responding MME to obtain the desired behaviour. This is, to accept flow 2 and either not send flow 3 or to delay sending flow 3 for sufficient time to allow the CBC to trigger a timeout. If the MME can be configured to not respond, then it shall not send any reponse whatsoever to flow 2.

TIP

One possibility to obtain the desired behaviour might be to disable CBS functionality in the MME. However, this may cause the MME to send an Error response to the CBC, which would invalidate the premise for the CBC to not receive an answer.

WARNING

If obtaining the desired behaviour from a real MME is not feasible, then either test with an MME emulator / simulator (e.g. a Valid8 one, if available) or ignore this TC.

Steps to execute

2. 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 is involved in this test.

Information flow

Result

Verify that:

1. The CBC sends a WRITE-REPLACE WARNING REQUEST to one of the MMEs (a) that control the eNBs in charge of the cells in the list. Presence of parameters in this message shall be as shown in the following table:

   Information Element	Included	Value
   Message Identifier	Yes	for current iteration
   Serial Number	Yes
   List of TAIs	Should	TAI of the cells in IE Warning Area List
   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 local language 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	No
   Global eNB ID	No

2. When the timer expires the CBC logs the condition and, if configured, raises and alarm towards the FM solution via SNMP.

3. The CBC sends an identical WRITE-REPLACE WARNING REQUEST as flow 2 to another MME (b) in the same pool as MME-a.

4. The MME responds with flow 4, indicating successful outcome in all the cells requested.

5. If the CBE-CBC interface support is, the CBC updates the CBE about the correct outcome for the alert request (flow 1).

6. If, after the timeout, a response is received from MME-a, then this response is logged and locally ignored (no further actions taken).