DRX Timer Management for Configured Uplink Grant Bundles
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Solution Overview
Problem
In wireless communication systems, particularly in the context of Discontinuous Reception (DRX) and configured uplink grants, there is an issue where the UE may not monitor the PDCCH for retransmissions of a bundle of a configured uplink grant due to the DRX timers expiring before the last transmission occasion, leading to missed uplink grants for retransmissions.
Innovation Solution
The solution involves modifying the DRX timer management by stopping the retransmission timer only for the initial transmission in a bundle and allowing it to run for subsequent retransmissions, ensuring the UE continues to monitor the PDCCH for uplink grants during the configured DRX period.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the DRX retransmission timer is stopped after the initial transmission in a bundle, then energy consumption is reduced and power saving is improved, but the UE may miss uplink grants for retransmissions leading to communication reliability degradation
Solution Approach 1:
The patent segments the DRX timer management into two distinct phases: initial transmission phase where the timer is stopped to save energy, and retransmission phase where the timer continues running to ensure reliability. This segmentation allows the system to optimize for energy during initial transmission while maintaining reliability during retransmission attempts.
Solution Approach 2:
The patent implements dynamic DRX timer management where the timer behavior changes based on the transmission stage. The timer is stopped after initial transmission to save energy, but continues running during the bundle retransmission period to ensure the UE can receive uplink grants. This dynamic adjustment resolves the contradiction between energy saving and reliability.
2Use of energy by stationary object
If the DRX timer is stopped early to save power, then power saving is improved, but the UE monitoring of PDCCH for retransmissions is interrupted leading to loss of uplink grants
Solution Approach 1:
The patent applies preliminary action by configuring the DRX timer to continue running during the bundle retransmission period before any actual retransmission occurs. This ensures that when uplink grants for retransmissions are sent, the UE is already in a state to monitor and receive them, preventing loss of uplink grants while still allowing power saving during the initial transmission phase.
3Reliability
If the UE monitors PDCCH continuously for retransmissions, then communication reliability is maintained, but energy consumption increases due to extended DRX timer operation
Solution Approach 1:
The patent applies local quality by making the DRX timer behavior different for different transmission stages within the bundle. During initial transmission, the timer is stopped to save energy. During the retransmission period, the timer continues running locally only for the duration needed to receive retransmission grants, then stops. This localized timer management maintains reliability only where needed while minimizing overall energy consumption.
Data Source
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AI summary
A method and apparatus are disclosed. In an example from the perspective of a User Equipment, UE, configured with bundled transmission, the UE initializes a configured uplink grant (1605). The UE performs a plurality of transmissions within a bundle of a Medium Access Control Protocol Data Unit, MAC PDU, using the configured uplink grant (1610). The UE stops a Discontinuous Reception, DRX, timer in response to a first transmission of the plurality of transmissions, wherein the DRX timer is not stopped in response to one or more second transmissions of the plurality of transmissions (1615). When the DRX timer is running, the UE monitors a downlink control channel for an uplink grant for retransmission (1620).