Question: In UTRAN's Iub interface, what happens to Mac-d flows from each carrier when Multi-Carrier E-DCH Transport Bearer Mode LCR is set to "Separate Iub transport bearer mode"?
Option 1: Each carrier's Mac-d flow is multiplexed onto a single Iub transport bearer.
Option 2: Mac-d flows from different carriers share the same Iub transport bearer but with prioritization.
Option 3: Each carrier's Mac-d flow uses a different Iub transport bearer.
Option 4: The Node B aggregates all Mac-d flows into a single logical Iub transport bearer.
Explanation: According to the Multi-Carrier E-DCH Transport Bearer Mode settings, when LCR is set to "Separate Iub transport bearer mode", each carrier's Mac-d flow utilizes a distinct Iub transport bearer. This setup ensures that each carrier's data is transmitted over its own dedicated bearer, enhancing manageability and potentially reducing congestion between carriers.