Summary Data

Revision History

The MME uses the SBc interface, between the MME and the Cell Broadcast Center (CBC), for warning message delivery and control functions.

The MME supports a Commercial Mobile Alert System (CMAS)—SBc interface and underlying protocols. CBC sends Warning Messages over the SBc-AP interface and relays to all relevant eNodeBs over the S1-AP interface.

MME upon receiving Public Warning System (PWS) failure or restart indication starts a CBC transaction to notify MME on the failure or restart.

Note	MME supports only up to 256 maximum elements in PWS Restart-TAI-List. If the eNodeB sends more than 256 elements, the PWS Restart Indication message does not get relayed to the CBC.

Session manager and MME manager facility stack are updated to handle the PWS failure and restart indications.

The CMAS functionality is enabled in the networks to provide warning notifications to subscribers.

Important

A valid license key is required to enable the SBc interface. Contact your Cisco account representative for information on how to obtain a license.

The MME accepts incoming SBc associations coming from multiple CBCs.

The MME is responsible for the delivery of the Warning Messages received from CBC to all relevant eNodeBs serving the given TAI list. In the absence of TAI list in the received Warning Message, MME sends the Warning Message to all connected eNodeBs.

The MME acknowledges to CBC when it has started distributing the Warning Message to all relevant eNodeBs. If a response is not received from any eNodeB, it shall not result in any exclusive error messaging to CBC.

Even if the MME node is experiencing congestion, Warning Messages are forwarded and not dropped.

When connected to multiple CBCs, the uniqueness of Warning Messages as identified by Message Type, Message Identifier and Serial Number, must be ensured across these CBCs.