Question: What is the scope of uniqueness for a Priority Queue ID in UTRAN's Iub interface NBAP signalling?
Option 1: Unique globally across all UTRAN networks
Option 2: Unique per User Equipment (UE) within a Node B
Option 3: Unique per cell, but can be reused across different carriers in TDD
Option 4: Unique across all MAC-d flows for one Node B Communication Context or all Common MAC flows within a specified domain (cell for FDD, carrier for 1.28Mcps TDD)
Explanation: The correct answer reflects the nuanced scope of uniqueness as defined by the standard. A Priority Queue ID must be unique to prevent conflicts, but this uniqueness is bounded by the context of a single Node B's communication scope or within specific domains (entire cell for FDD, entire carrier for 1.28Mcps TDD). This ensures efficient management of MAC-d flows without requiring global uniqueness, which would be unnecessarily restrictive.