Access Terminal Drift Compensation During Sleep Mode
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Solution Overview
Problem
Wireless access terminals experience component drifts during sleep times, leading to adverse effects on communication system performance and battery life due to uncontrolled variations in oscillator clocks, which can cause failure in decoding paging channels and increase power consumption.
Innovation Solution
A method and apparatus for compensating drifts in access terminals during sleep times by determining if the sleep time exceeds a threshold, buffering time domain samples containing acquisition pilots and a paging channel, powering down RF circuitry, processing samples to correct for drift, and determining if the terminal was paged based on the processed samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the access terminal enters sleep mode to conserve battery power, then power consumption is reduced, but component drift occurs leading to degraded communication performance
Solution Approach 1:
The system performs preliminary actions by buffering time domain samples containing acquisition pilots and paging channel before entering sleep mode. This allows the terminal to wake up later with reduced drift impact while still having the necessary signal data available for processing, thus extending sleep duration without sacrificing communication reliability
Solution Approach 2:
The patent replaces the mechanical approach of keeping RF circuitry continuously powered with a digital signal processing approach. By buffering samples and performing drift compensation through digital processing of the buffered data, the system substitutes hardware continuous operation with software-based correction, enabling longer sleep periods while maintaining performance
2Duration of action of moving object
If the access terminal buffers time domain samples and powers down RF circuitry, then standby time is extended, but processing complexity increases to compensate for drift
Solution Approach 1:
The system extracts only the essential time domain samples containing acquisition pilots and paging channel information for buffering, rather than buffering all received signals. This selective extraction minimizes the amount of data requiring complex processing while still providing sufficient information for drift compensation and paging detection
Solution Approach 2:
The patent creates a digital copy of the time domain samples in buffer memory before powering down RF circuitry. This digital copy preserves the signal characteristics needed for drift compensation without requiring the physical RF hardware to remain active, simplifying the power management while maintaining processing capability
Data Source
AI summary
A method and apparatus are presented for compensating drifts in access terminals occurring during a sleep time. The method includes determining whether a sleep time exceeds a threshold, buffering time domain samples containing acquisition pilots and a paging channel, powering down RF circuitry in the access terminal after buffering samples, processing the samples to compensate for drift, and determining whether the access terminal was paged based upon the processed samples. The apparatus includes a digital front end, an FFT engine coupled to the digital front end, a symbol buffer coupled to the FFT engine, a processor coupled to the digital front end, FFT engine, and symbol buffer, and a memory coupled to the processor, the memory further comprising instructions for executing the method.