Question: Upon receiving an SIB8 with incomplete warning message segments, what action(s) does the UE take if the received `messageIdentifier` and `serialNumber` do not match any currently assembled warning message pairs?
Option 1: Discard all stored warning message segments and stop reception of SIB8.
Option 2: Forward incomplete warning messages to upper layers for processing.
Option 3: Continue reception of SIB8 but do not store new segments until a match is found.
Option 4: Start assembling a new warning message for the received `messageIdentifier` and `serialNumber` pair, storing the received segments.
Explanation: When the UE receives an SIB8 with incomplete warning message segments and the `messageIdentifier` and `serialNumber` do not match any currently assembled pairs, it initiates the assembly process for this new pair. This involves starting to assemble both the warning message and its geographical coordinates (if included), storing the received segments, and continuing to receive SIB8 to collect all necessary parts for complete assembly. This approach ensures the UE can handle multiple, simultaneous assemblies based on different `messageIdentifier` and `serialNumber` pairs, as limited by UE implementation capabilities.