UE-Network DRX Timer Coordination for Lower Latency and Power Use
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Solution Overview
Problem
In wireless communication systems, the mismatch between UE and network entity timers during discontinuous reception (DRX) cycles leads to increased latency and power consumption due to uncoordinated signal transmissions and receptions, particularly when the UE enters sleep mode unexpectedly.
Innovation Solution
The UE transmits a first uplink signal indicating whether it expects to restart timers or enter DRX, coordinating with the network entity to align sleep and awake modes, thereby reducing latency and power consumption by ensuring synchronized signal transmissions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the UE enters sleep mode based on timer expiration without coordination, then power consumption is reduced, but latency increases due to uncoordinated signal transmissions
Solution Approach 1:
The UE transmits an indicator signal before entering sleep mode to notify the network entity of its intention. This preliminary action allows the network to prepare for coordinated transmission, ensuring that critical signals are sent before the UE sleeps, thereby reducing latency while still enabling power saving mode.
Solution Approach 2:
The UE provides feedback to the network entity through the indicator signal about its DRX timer status and sleep mode intention. This feedback mechanism enables the network to adjust its transmission schedule accordingly, coordinating downlink signals with the UE's awake/sleep cycles to minimize latency and power consumption.
2Reliability
If the UE monitors for downlink signals continuously, then communication reliability is improved, but power consumption increases
Solution Approach 1:
Instead of continuous monitoring, the UE uses periodic C-DRX cycles with configured awake and sleep periods. The indicator signal mechanism ensures that during sleep periods, the UE can reliably receive critical downlink signals when awake, maintaining communication reliability while significantly reducing power consumption during sleep periods.
3Productivity
If the network entity transmits signals during UE sleep mode, then productivity is improved, but the UE cannot receive signals causing retransmissions
Solution Approach 1:
The UE sends an indicator signal before entering sleep mode to inform the network entity of its sleep intention. This allows the network to schedule downlink transmissions strategically - sending critical signals before the UE sleeps or using wake-up mechanisms - thereby maintaining both transmission productivity and reception reliability.
Solution Approach 2:
The indicator signal provides feedback to the network about the UE's sleep status, enabling the network to coordinate transmissions accordingly. This feedback loop ensures that the network can efficiently use sleep periods for other operations while ensuring reliable signal delivery when the UE is awake.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. The techniques described herein relate to coordinating discontinuous reception (DRX) timers between a user equipment (UE) and a network entity. A UE receives a first downlink message that updates one or more timers associated with triggering a connected mode discontinuous reception (C-DRX) at the UE. The UE transmits a first uplink message prior to an expiration of the one or more timers associated with triggering the C-DRX. The first uplink message indicates whether the UE expects to restart the one or more timers or to enter the C-DRX following transmission of the first uplink message. The UE selects to enter the C-DRX or remain in an awake state following transmission of the first uplink message based on a status of the one or more timers associated with triggering the C-DRX at the UE and the indication of the first uplink message.