LTE UE CQI Reporting Timing Optimization for DRX Power Saving
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Solution Overview
Problem
In LTE systems, user equipment (UE) needs to wake up frequently to report channel quality information (CQI) during connected discontinuous reception (DRX) mode, leading to increased power consumption and reduced battery life, as it must wake up early to monitor downlink channels for periodic CQI reports.
Innovation Solution
The method involves determining whether to use CQI measurements from the last subframe of a previous DRX cycle as a basis for reporting CQI during the next on-duration, allowing the UE to wake up later and reducing the duration of being awake, thereby conserving power. This is achieved by implementing a Resume-CQI mode when certain conditions are met, such as sufficient off-period between wake-ups and a short maximum time between CQI measurement and report.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the UE wakes up early to monitor downlink channels for periodic CQI reports, then the CQI reporting accuracy is improved, but the power consumption increases and battery life decreases
Solution Approach 1:
The UE performs CQI measurements in advance during the previous DRX cycle active time and stores them for later reporting. This allows the UE to wake up later while still having valid CQI measurements to report, resolving the contradiction between early wake-up for accurate reporting and late wake-up for power saving.
Solution Approach 2:
The patent dynamically adjusts the CQI reporting strategy based on whether the UE wakes up early or late. When waking up late, the UE uses stored measurements from previous cycles; when waking up early, it performs fresh measurements. This dynamic adaptation allows the system to optimize between measurement accuracy and power consumption based on actual wake-up timing.
2Use of energy by moving object
If the UE wakes up as late as possible to conserve battery life, then the power consumption is reduced, but the UE may miss the opportunity to perform fresh CQI measurements
Solution Approach 1:
The UE performs CQI measurements in advance during the previous DRX cycle active time and stores them for later reporting. This preliminary action ensures that even when the UE wakes up late to save power, it still has valid CQI measurements available for reporting, eliminating the need to wake up early for fresh measurements.
3Loss of time
If the UE uses CQI measurements from previous DRX cycle, then the wake-up time is reduced and power consumption decreases, but the CQI data may be less accurate for current channel conditions
Solution Approach 1:
The UE performs CQI measurements in advance during the previous DRX cycle active time and stores them for later reporting. This preliminary action allows the UE to use these stored measurements when waking up late, reducing wake-up time and power consumption while maintaining acceptable CQI reporting capability.
Solution Approach 2:
The patent dynamically adjusts the CQI reporting strategy based on actual wake-up timing. When the UE wakes up late, it uses stored measurements from previous cycles; when it wakes up early enough, it performs fresh measurements. This dynamic approach optimizes the trade-off between using old measurements and performing new measurements based on actual system conditions.
Data Source
AI summary
A method, an apparatus, and a computer program product for wireless communication are provided. The apparatus determines whether a channel quality indicator (CQI) is to be reported during any one of x subframes immediately after a start of a next on-duration, an on-duration being a duration over which a downlink control channel is monitored every discontinuous reception (DRX) cycle, and x being a number of subframes used to generate a CQI report, schedules a wake-up time for reporting the CQI when the CQI is to be reported during any one of the x subframes immediately after the start of the next on-duration, and reports the CQI based on a reference subframe. The CQI may be based on a last subframe of a previous DRX cycle active time, and reported at a first subframe of the next on-duration.