Question: What is the primary requirement for introducing new PDU types in the RRC protocol to ensure interoperability between implementations based on different versions?
Option 1: Minimize the number of additional fields introduced
Option 2: Ensure backward compatibility by using only critical extension mechanisms
Option 3: Define a new logical channel for the transfer of extended PDUs
Option 4: Prevent unexpected behavior or damage, allowing implementations to ignore uncomprehended extensions
Explanation: To maintain interoperability, introducing new PDU types must not cause disruptions. This means ensuring that receivers can handle new types without issues, specifically by being able to ignore any uncomprehended (new) elements without affecting the processing of the rest of the message, which aligns with the principle of preventing unexpected behavior or damage as stated in Option 4.