Frequency Offset Correction in Wireless Devices
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Solution Overview
Problem
Conventional methods for estimating and correcting frequency offsets between WWAN and WLAN reference clocks in wireless communication devices are complex and introduce latency, particularly when these devices operate in assistance modes like carrier aggregation or dual SIM/dual active modes.
Innovation Solution
A frequency control subsystem measures and corrects frequency offsets between WWAN and WLAN reference clocks by identifying trigger factors, such as sleep cycles and signal strength, and adjusts the latching intervals to reduce latency and improve accuracy, allowing for efficient resource sharing and assistance between radios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods for estimating and correcting frequency offsets are used, then frequency synchronization is achieved, but system latency increases and complexity increases
Solution Approach 1:
The patent performs frequency offset estimation and correction in advance, before the actual data transmission occurs. The system measures the frequency offset between WWAN and WLAN reference clocks during idle periods or before assistance mode activation, stores the measured offset values, and applies them when needed. This preliminary action eliminates the need for time-consuming measurements during critical data transmission periods, thereby reducing system latency while maintaining frequency synchronization accuracy.
Solution Approach 2:
The patent performs frequency offset estimation and correction in advance, before the actual data transmission occurs. The system measures the frequency offset between WWAN and WLAN reference clocks during idle periods or before assistance mode activation, stores the measured offset values, and applies them when needed. This preliminary action eliminates the need for time-consuming measurements during critical data transmission periods, thereby reducing system latency while maintaining frequency synchronization accuracy.
2Reliability
If conventional frequency offset correction methods are used, then frequency synchronization is achieved, but device complexity increases
Solution Approach 1:
The patent implements a self-service mechanism where the WLAN radio automatically assists the WWAN radio in frequency offset measurement and correction without requiring complex external control systems. The WLAN radio independently measures the frequency offset, stores the correction values, and applies them during assistance mode operations. This self-service approach simplifies the overall system architecture by eliminating the need for complex coordinated control mechanisms between multiple radios, thereby reducing device complexity while achieving reliable frequency synchronization.
Data Source
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AI summary
A user equipment may identify one or more trigger factors associated with an assistance mode. The assistance mode may include a second radio associated with a second radio access technology (RAT) assisting a first radio associated with a first RAT. The UE may then measure a frequency offset between a first clock of the first radio and a second clock of the second radio based at least in part on the one or more trigger factors. The first clock may be associated with a first oscillator crystal, and the second clock may be associated with a second oscillator crystal. The UE may then store the frequency offset for use by the first radio and the second radio in the assistance mode.