Question: What determines the accuracy of sub-band channel quality indicator (CQI) reporting under frequency-selective fading conditions?
Option 1: A single-sided percentile of the reported differential CQI offset level per sub-band
Option 2: The absolute value of the reported differential CQI offset level per sub-band
Option 3: A double-sided percentile of the reported differential CQI offset level per sub-band and the relative increase of throughput obtained when transmitting on a randomly selected sub-band among the sub-bands with the highest reported differential CQI offset level
Option 4: The average value of the reported differential CQI offset level per sub-band
Explanation: According to the specifications, the accuracy of sub-band channel quality indicator (CQI) reporting under frequency-selective fading conditions is determined by a double-sided percentile of the reported differential CQI offset level per sub-band and the relative increase of throughput obtained when transmitting on a randomly selected sub-band among the sub-bands with the highest reported differential CQI offset level. This ensures that preferred sub-bands can be used for frequency-selective scheduling, taking into account sensitivity to input SNR levels.