Question: What is the significance of the DL DPCH Timing Adjustment in UTRAN's Iub interface, and what is the fixed magnitude of each adjustment?
Option 1: It signals a power adjustment for the downlink dedicated physical channel (DPCH), with adjustments varying in increments of 128 chips.
Option 2: It indicates a timing adjustment (advance or delay) for the related radio link, with each adjustment always consisting of a fixed 256 chips magnitude.
Option 3: It notifies of a change in the downlink DPCH's modulation scheme, with adjustments dependent on the SFN timing context.
Option 4: It confirms the completion of an Initial DL DPCH Timing Adjustment without specifying the adjustment's direction or magnitude.
Explanation: The correct answer, Option 2, accurately reflects the role of the DL DPCH Timing Adjustment in adjusting the timing of the related radio link by either advancing or delaying it relative to the SFN (System Frame Number) timing, with each adjustment being precisely 256 chips. This understanding is crucial for maintaining synchronization and optimal performance in UTRAN networks.