Wake-Up Signal Alignment for DRX Control Channel Reception
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Solution Overview
Problem
In 5G NR systems operating at high frequencies, beam blockage can occur during discontinuous reception (DRX) periods, leading to communication failures and increased power consumption due to the need for continuous monitoring.
Innovation Solution
A method and system for control channel reception in power save mode using a wake-up signal (WUS) transmitted prior to the DRX ON period with a shared quasi-colocated (QCL) source for both the WUS and control channel, ensuring consistent spatial alignment and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If beamforming is used to overcome high pathloss at high frequencies, then communication reliability is improved, but device complexity increases due to beam management requirements
Solution Approach 1:
The access node transmits a wake-up signal using a first beam before the control channel transmission. The UE receives this wake-up signal and determines the spatial quasi-colocated source in advance, preparing the receiver for the upcoming control channel on a second beam. This preliminary action simplifies beam management by pre-establishing spatial relationships.
Solution Approach 2:
The wake-up signal acts as an intermediary between the access node and the control channel transmission. It carries spatial quasi-colocation information that mediates the beam alignment process, allowing the UE to configure its receiver appropriately for the control channel without requiring complex real-time beam switching.
2Use of energy by moving object
If discontinuous reception is used to save power, then energy consumption is reduced, but detection probability of control channels deteriorates
Solution Approach 1:
The access node transmits a wake-up signal before the control channel during the DRX ON period. The UE receives this signal in advance and uses the spatial quasi-colocated source information to configure its receiver for the upcoming control channel, improving detection probability while maintaining power savings during DRX OFF periods.
Solution Approach 2:
The wake-up signal provides feedback information about the spatial quasi-colocated source to the UE. This feedback enables the UE to adjust its receiver configuration optimally for the control channel transmission, ensuring reliable detection even in discontinuous reception mode.
3Reliability
If different beams are used for wake-up signal and control channel, then spatial diversity is improved, but detection probability deteriorates due to spatial misalignment
Solution Approach 1:
The patent establishes a parameter relationship between the first beam (wake-up signal) and second beam (control channel) through the spatial quasi-colocated source. By changing the beam parameters such that they share a common spatial reference, the system maintains both spatial diversity and detection probability.
Solution Approach 2:
The wake-up signal and control channel are configured to share a common spatial quasi-colocated source, creating homogeneity in their spatial characteristics. This ensures that the UE can use the same spatial filter and receiver configuration for both signals, improving detection probability while maintaining beamforming benefits.
Data Source
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AI summary
The application discloses determining that a media access control (MAC) entity of a user equipment (UE) is in Active Time during a predetermined window for transmitting a wake up signal (WUS) prior to a discontinuous reception (DRX) ON period and, based on the determining, not transmitting by the access node, the WUS to the UE during the predetermined window prior to the DRX ON period or deactivating, by the UE, WUS reception of the UE during the expected transmission time of the first WUS before the first DRX ON period.