CSI-RS Transmission Coordination for UE Power Saving
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Solution Overview
Problem
In wireless communication devices, particularly during 5G-NR communications, the frequent awakening of User Equipment (UE) to receive channel state information reference signals (CSI-RS) outside scheduled wake-up periods leads to premature battery drain due to misalignment between CSI-RS occasions and UE's C-DRX on-duration periods.
Innovation Solution
The base station coordinates CSI-RS transmissions with UE's C-DRX on-duration periods by suspending or adjusting CSI-RS transmissions to prevent early wake-ups, using aperiodic CSI-RS transmissions that coincide with UE's on-duration periods, allowing UE to measure and report CSI without exiting a low-power state prematurely.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base station transmits CSI-RS according to a fixed periodic schedule, then the CSI measurement accuracy is improved, but the UE battery life deteriorates due to premature wake-ups outside C-DRX on-duration periods
Solution Approach 1:
The patent makes the CSI-RS transmission schedule dynamic by allowing the base station to adjust transmission timing based on UE C-DRX state. Instead of a fixed periodic schedule, the base station monitors UE wake-up patterns and dynamically aligns CSI-RS transmissions with C-DRX on-duration periods, resolving the contradiction between measurement accuracy and battery life
Solution Approach 2:
The patent changes the timing parameter of CSI-RS transmissions from a fixed periodic value to a flexible value that adapts to UE C-DRX configuration. The base station modifies transmission parameters (timing offset, periodicity) to match UE wake-up schedules, ensuring accurate CSI measurements are obtained during active periods without causing premature battery drain
2Loss of time
If the UE wakes up early to receive CSI-RS outside C-DRX on-duration periods, then the CSI report timeliness is improved, but the power consumption increases due to unnecessary wake-ups
Solution Approach 1:
The base station performs preliminary action by proactively adjusting CSI-RS transmission timing to coincide with upcoming C-DRX on-duration periods. This prevents the need for UE to wake up early, as the reference signals are already scheduled to arrive during planned active periods, maintaining timeliness while avoiding unnecessary energy loss
Solution Approach 2:
The system implements feedback mechanisms where the base station monitors UE C-DRX operation and CSI report timing requirements, then uses this feedback to optimize CSI-RS transmission scheduling. This closed-loop approach ensures timeliness is maintained while minimizing power consumption by eliminating mismatched wake-up events
3Use of energy by moving object
If the base station suspends CSI-RS transmissions to save UE power, then the battery life is improved, but the CSI measurement accuracy deteriorates
Solution Approach 1:
Rather than completely suspending CSI-RS transmissions, the patent dynamically adjusts transmission timing to occur during UE C-DRX on-duration periods. This dynamic scheduling ensures transmissions are not lost but rather relocated to appropriate time windows, preserving measurement accuracy while achieving power savings by avoiding transmissions during sleep periods
4Loss of energy
If the UE remains in low-power state during scheduled CSI-RS occasions, then the power consumption is reduced, but the CSI report quality deteriorates due to outdated channel state information
Solution Approach 1:
The base station takes preliminary action by scheduling CSI-RS transmissions to occur just before UE C-DRX on-duration periods begin. This ensures fresh channel state information is available when the UE wakes up, maintaining report quality without requiring the UE to extend its active period or wake up prematurely
Solution Approach 2:
The patent changes the timing parameters of CSI-RS transmissions to align with UE C-DRX cycle characteristics. By adjusting transmission timing offsets and periodicity to match UE wake-up patterns, the system ensures up-to-date CSI is obtained during active periods while maintaining low power consumption during sleep periods
Data Source
AI summary
A base station and mobile device (UE) may coordinate transmission of reference signals and reception of corresponding channel state information (CSI) reports. If a periodic reference signal is scheduled for transmission outside the on-duration period of the UE, even if the reference signal corresponds to a periodic CSI report scheduled to be transmitted by the UE during the on-duration period, the base station may not transmit the periodic reference signal, thereby allowing the UE not to prematurely exit a low-power state. The base station may instead transmit an aperiodic reference signal at a specified point in time later than the scheduled transmission of the periodic reference signal. The UE may receive the aperiodic reference signal and either transmit the periodic CSI report or an aperiodic CSI report in response, depending on how close to the start of the on-duration period the transmission of the periodic CSI report is scheduled.