DRX Wake-Up Signal Mobility Robustness
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Solution Overview
Problem
Current wireless communication technologies face challenges in maintaining mobility robustness and power efficiency for devices using discontinuous reception (DRX) modes, particularly with the introduction of wake-up signals (WUS) that can lead to reduced paging robustness and increased power consumption for mobile UEs.
Innovation Solution
A method and system that determine whether a wireless device has changed cells, allowing it to skip decoding wake-up signals if it has moved to a new cell, and monitor all paging occasions within a paging time window to ensure reliable paging and reduce power consumption by automatically falling back to Release-13 behavior when necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If wake-up signals are used to indicate whether UE needs to decode subsequent physical channels, then power consumption is reduced, but mobility robustness deteriorates when UE changes cells
Solution Approach 1:
The patent implements dynamic behavior where the UE adapts its paging monitoring strategy based on cell change detection. When a cell change is detected, the UE transitions from skipping paging occasions (power-saving mode) to monitoring all paging occasions (robustness mode). This dynamic adaptation resolves the contradiction by allowing the system to operate in power-saving mode during stable conditions and switch to robustness mode when mobility occurs.
Solution Approach 2:
The patent changes the operational parameters of the UE based on the detected cell state. Specifically, it modifies the paging monitoring behavior parameter: in the same cell, the UE uses wake-up signal-based skipping of paging occasions; upon cell change detection, the UE switches to monitoring all paging occasions within the paging time window. This parameter change enables the system to balance power consumption and mobility robustness based on actual operational conditions.
2Use of energy by moving object
If UE skips decoding wake-up signals in the same cell, then power consumption is reduced, but paging reliability may deteriorate
Solution Approach 1:
The patent performs preliminary cell change detection before the UE skips paging occasions. By detecting whether the UE is in the same cell as before using previously received system information, the system ensures that skipping paging occasions is only performed when it is safe to do so. This preliminary action prevents paging reliability deterioration while maintaining power savings.
Solution Approach 2:
The patent implements a feedback mechanism where the UE continuously monitors for cell changes by comparing current cell identity with previously stored cell information. This feedback loop ensures that the UE can reliably detect when to switch between power-saving mode and robust monitoring mode, maintaining paging reliability while optimizing power consumption based on actual cell stability.
3Reliability
If UE monitors all paging occasions after cell change, then mobility robustness is improved, but power consumption increases
Solution Approach 1:
The patent implements dynamic paging monitoring behavior that adapts to mobility conditions. After detecting a cell change, the UE temporarily monitors all paging occasions within the paging time window to ensure robustness during the transition period. Once cell stability is confirmed, the UE returns to the power-saving mode of skipping paging occasions. This dynamic approach ensures mobility robustness is improved only when necessary, minimizing unnecessary power consumption.
4Use of energy by moving object
If wake-up signal opportunity is missed in new cell, then power consumption is saved by skipping, but paging delivery reliability deteriorates
Solution Approach 1:
The patent performs preliminary detection of cell changes before the UE attempts to use wake-up signal-based paging skipping. By checking whether the UE is in a new cell using previously received system information, the system prevents the UE from skipping paging occasions in new cells where wake-up signals may not be properly received. This preliminary action ensures paging delivery reliability is maintained during cell transitions while still allowing power-saving skipping in stable cells.
Data Source
AI summary
According to an embodiment, a method for use in a wireless device is provided. The method comprises waking up from a discontinuous reception (DRX) mode in a cell. The method further comprises determining whether the cell is the same as a previous cell of the wireless device. In response to determining that the cell is not the same as the previous cell, the method further comprises determining whether the wireless device missed a wake-up signal opportunity in the cell. The method further comprises monitoring each of the paging occasions associated with the wake-up signal opportunity if the cell is not the same as the previous cell and the wake-up signal opportunity was missed.