Question: During the pre-emption process in UTRAN's Iub interface (NBAP signalling), how does a Node B select Radio Links for pre-emption when resources need to be freed for a new or modified Radio Link?
Option 1: In descending order of their retention priority, until sufficient resources are available.
Option 2: Randomly among all active Radio Links with lower retention priority than the new allocation.
Option 3: Based on the type of service (e.g., voice, data) associated with each Radio Link.
Option 4: In ascending order of their retention priority, until enough resources are freed.
Explanation: This is correct because the pre-emption process is designed to minimize disruption by first targeting Radio Links with the lowest retention priority. Selecting in ascending order ensures that only the least prioritized connections are impacted, preserving more critical communications as long as possible. This approach aligns with efficient resource management and service continuity principles in telecommunication networks.