Question: For a UTRA FDD User Equipment (UE) supporting UL CLTD and HSDPA, from Release 11 onwards, what is the primary basis for calculating the Adjacent Channel Leakage Ratio (ACLR)?
Option 1: The ratio of the peak power to the mean power within the assigned channel frequency.
Option 2: The ratio of the filtered mean power centred on the assigned channel frequency to the filtered mean power centred on an adjacent channel frequency.
Option 3: Comparison of signal strengths between two adjacent base stations.
Option 4: Measurement of latency in data transmission between the UE and the base station.
Explanation: ACLR is a crucial metric for assessing the out-of-band emission of a transmitter. It specifically measures how much power leaks into adjacent channels, which is vital for preventing interference with other communications. The correct definition, as per telecom standards for such measurements, involves comparing the mean power centered on the assigned channel frequency to that of an adjacent channel frequency after filtering, ensuring accurate assessment of leakage. This directly impacts the quality of service in wireless networks by minimizing cross-channel interference.