name: PWS
full_form: Public Warning System
context: Even if the frequency of PWS key update is rather low, it should also provide a mechanism to permit PWS key to be updated. This solution uses a point-to-point secure channel to update PWS keys. The network activates and updates PWS keys as follows: - Two PWS keys are used: the current PWS key and the next PWS key. The current one is the activated one which is used to verify the current PWS notification; the next PWS key is used to verify the PWS notification after it has been activated when the current one is deactivated. - When CBC determines to change the next PWS key to current PWS keys, it shall also update the next PWS key with a new one. And CBC shall send the updated next PWS key and its identifier to the network entities (MME/SGSN), together with the current PWS key identifier. Figure A.2.4.1: PWS key activates and updates by network side UE activates and updates PWS keys as follows: - The serving network always broadcasts the current PWS key identifier and the next PWS key
description: Public Warning System (PWS) is a telecommunications service that enables authorized entities to broadcast critical information to mobile devices in emergency situations, such as natural disasters or Amber Alerts. The system utilizes secure channels and key updates to ensure the authenticity and integrity of warning messages.
explanation: The context describes PWS as a system for broadcasting critical information via mobile devices during emergencies, aligning with the definition of a telecommunications service.  Features like secure channels and key updates further solidify its classification.
section_title: A.2.4	PWS key update
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