DRX Timer Management for Wireless UE Power and Latency
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing Discontinuous Reception (DRX) operations, particularly in next-generation networks like 5G, where two-stage scheduling and 2-step granting mechanisms complicate the timing of uplink and downlink transmissions, leading to potential data transmission delays and increased power consumption due to unnecessary monitoring.
Innovation Solution
The introduction of a new timer, ul-GrantValidTimer, and adjustments to existing DRX timers such as drx-InactivityTimer and drx-ULRetransmissionTimer, to ensure that user equipment (UE) only monitors the PDCCH within valid time frames for uplink and downlink transmissions, and the use of MAC control signaling to stop retransmission timers when not necessary, optimizing power usage and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE monitors PDCCH continuously for uplink and downlink transmissions, then data transmission reliability is improved, but power consumption increases
Solution Approach 1:
The patent implements discontinuous reception (DRX) where the UE alternates between active monitoring periods and sleep periods. The UE monitors PDCCH during active time defined by DRX timers (drx-InactivityTimer, drx-ULRetransmissionTimer, drx-HARQ-RTT-Timer) and enters sleep mode when timers expire, creating a periodic monitoring pattern that reduces power consumption while maintaining transmission reliability through timer-based wake-up triggers.
2Manufacturing precision
If UE monitors PDCCH during all DRX time periods, then transmission timing accuracy is improved, but unnecessary monitoring increases power consumption
Solution Approach 1:
The patent dynamically adjusts the UE's PDCCH monitoring behavior based on the state of DRX timers and reception status. The UE monitors PDCCH only when DRX timers are running (drx-InactivityTimer, drx-ULRetransmissionTimer, drx-HARQ-RTT-Timer) and stops monitoring when timers expire or when no transmission is expected, making the monitoring pattern adaptive to actual transmission needs rather than static.
Solution Approach 2:
The patent changes the monitoring parameter (PDCCH monitoring activation) based on timer state parameters. The UE transitions between monitoring and non-monitoring states by evaluating whether DRX timers are running, effectively using parameter changes to control power consumption while maintaining timing accuracy for actual transmissions.
3Adaptability or versatility
If multiple DRX timers are running simultaneously for uplink and downlink, then comprehensive transmission coverage is improved, but timer management complexity increases
Solution Approach 1:
The patent segments the DRX timer management into three distinct timer types with specific functions: drx-InactivityTimer for downlink retransmissions, drx-ULRetransmissionTimer for uplink retransmissions, and drx-HARQ-RTT-Timer for HARQ round-trip timing. Each timer is independently managed and triggered by specific events, dividing the complex timer management task into manageable segments with clear responsibilities.
Solution Approach 2:
The patent creates a universal DRX timer management framework that handles both uplink and downlink transmissions through a common set of timer mechanisms. The same timer structure and management logic apply to both uplink and downlink directions, providing a unified solution that covers comprehensive transmission scenarios while avoiding separate complex management systems for each direction.
4Use of energy by moving object
If UE stops DRX timers early to save power, then power consumption is reduced, but data transmission delays may occur
Solution Approach 1:
The patent implements feedback mechanisms where the network sends downlink assignments and uplink grants that trigger DRX timer restarts. When the network has data to transmit or needs uplink resources, it sends signaling that restarts the appropriate DRX timers, ensuring the UE wakes up in time for actual transmissions. This feedback loop prevents premature timer expiration and associated delays while maintaining power savings during idle periods.
Data Source
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AI summary
A method and apparatus are disclosed from the perspective of a UE. The method includes monitoring a control channel for detection of an UL grant (1405). The method further includes receiving the UL grant associated with a HARQ process on the control channel at a first timing (1410). The method also includes sending an UL data associated with the UL grant on a data channel at a second timing (1415). In additional, the method also includes starting a retransmission timer associated with the HARQ process after detection of the UL grant at a third timing (1420). Furthermore, the method includes receiving a signaling indicating stop the retransmission timer at a fourth timing (1425). In addition, the method includes stopping the retransmission timer and stopping monitoring the control channel, wherein the UE monitors the control channel when the retransmission timer is running (1430).