UE Fast Timing Acquisition for DRX Power Savings
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Solution Overview
Problem
Current wireless communication systems face challenges in achieving fast timing acquisition and power savings, particularly in deep sleep scenarios and varied reception modes like Discontinuous Reception (DRX).
Innovation Solution
The method involves determining System Frame Number (SFN) hypotheses for a User Equipment (UE) to wake up from a sleep state, generating a detection metric based on a Physical Broadcast Control Channel (PBCH) sequence received from a base station, and determining the correct timing for communication based on the detection metric.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the UE wakes up earlier to acquire timing information, then timing acquisition speed is improved, but power consumption increases
Solution Approach 1:
The UE performs preliminary actions during the sleep state by maintaining a low-power clock source that continues to run, allowing the device to quickly calculate expected SFN values without needing to wake up early for timing acquisition. This preliminary preparation enables fast timing synchronization upon wake-up without extending the active reception window.
Solution Approach 2:
The system uses the UE's own low-power clock source to generate SFN hypotheses and perform timing acquisition, eliminating the need for extensive network-assisted timing information. The UE serves itself by using its internal clock to predict timing and validate against received PBCH sequences, reducing both wake-up time and power consumption.
2Measurement precision
If the UE maintains clock accuracy during sleep state, then timing synchronization is improved, but power consumption increases
Solution Approach 1:
Instead of maintaining high clock accuracy globally across all functions, the system applies different quality levels locally: a low-power, lower-accuracy clock runs during sleep for basic timing reference, while full clock accuracy is restored only when needed for actual communication. The timing acquisition algorithm compensates for the reduced accuracy by testing multiple SFN hypotheses.
Solution Approach 2:
The system changes the clock accuracy parameter dynamically based on operational state. During DRX sleep, the clock operates in a low-power mode with reduced accuracy. Upon wake-up, the system quickly evaluates multiple timing hypotheses and锁定s the correct timing, effectively managing the trade-off between power consumption and synchronization accuracy.
3Reliability
If the UE tests multiple SFN hypotheses, then timing acquisition reliability is improved, but processing time increases
Solution Approach 1:
The timing acquisition process is segmented into discrete SFN hypothesis tests based on the low-power clock's time stamp. Instead of exhaustively testing all possible SFN values, the system segments the search space into a limited set of hypotheses derived from the clock's measured drift, significantly reducing processing time while maintaining reliability.
Solution Approach 2:
The system uses feedback from PBCH sequence detection to validate each SFN hypothesis quickly. By comparing detected PBCH sequences against expected sequences for each hypothesis, the system can rapidly confirm or reject timing assumptions, reducing the overall processing time required to achieve reliable timing acquisition.
Data Source
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AI summary
Techniques performed by a User Equipment (UE) are provided for fast timing acquisition for Discontinuous Reception (DRX) cycles. The UE determines one or more System Frame Number (SFN) hypotheses. Each of the one or more SFN hypothesis can represent a possible SFN at which the UE can wake up from a sleep state of a Discontinuous Reception (DRX) cycle. For at least one of the one or more SFN hypotheses, the UE generates a detection metric based at least partially on a Physical Broadcast Channel (PBCH) sequence received from a base station, and determines, based on a value of the detection metric, whether the at least one SFN hypothesis represents a current SFN in accordance with a clock source used the base station for communicating with the UE. Other aspects, embodiments, and features are also claimed and described.