Idle Mode Inter-RAT Search Rate Control
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Solution Overview
Problem
Wireless communication devices face a challenge in efficiently searching for better cells while in idle mode, which consumes battery power and shortens standby time, as existing techniques do not effectively manage power consumption during inter-RAT cell reselection searches.
Innovation Solution
The device determines the difference in received signal levels between GSM and WCDMA frequency bands to adjust the rate and frequency of WCDMA searches, using factors like path loss ratios and signal thresholds to optimize power usage and reduce unnecessary searches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE periodically searches for better cells in the same system or another system while camped on the serving cell, then the UE can reliably receive incoming paging messages and initiate or receive calls, but the searches consume battery power and shorten standby time
Solution Approach 1:
The patent implements dynamic adjustment of search behavior based on signal quality conditions. When the signal quality of the serving cell is good, the UE reduces or suspends searches for other systems. When signal quality deteriorates below a threshold, the UE activates searches for alternative systems. This dynamic adaptation allows the system to maintain reliability only when necessary, significantly reducing power consumption during normal operation while ensuring service continuity when needed.
Solution Approach 2:
The patent changes the parameter of search frequency based on signal quality measurements. By monitoring the serving cell's signal quality and comparing it against thresholds, the system adjusts the search rate for other RATs accordingly. This parameter change strategy ensures that intensive searches are performed only when the serving cell quality degrades, balancing reliability requirements with power conservation.
2Speed
If the UE performs inter-RAT cell reselection searches frequently, then the UE can find better cells timely, but the power consumption increases and standby time decreases
Solution Approach 1:
The patent implements periodic searches for other RATs triggered by signal quality conditions. Instead of continuous searching, the system performs searches at periodic intervals only when the serving cell's signal quality falls below a predetermined threshold. This periodic action based on trigger conditions maintains the ability to find better cells timely while avoiding the power waste of continuous searching during good signal conditions.
Solution Approach 2:
The system dynamically adjusts the speed of cell search based on real-time signal quality assessment. When signal quality is good, the search speed is reduced or suspended. When signal quality deteriorates, the search speed increases to find alternative cells more quickly. This dynamic speed adjustment ensures timely cell reselection when necessary while conserving power during stable conditions.
Data Source
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AI summary
Techniques for performing searches by a user equipment (UE) are described. The UE may camp on a serving cell for a first radio access technology (RAT) (e.g., GSM) and may periodically perform searches for a second RAT (e.g., WCDMA). In an aspect, the UE may vary the rate of searches for the second RAT based on received signal levels for the first and second RATs. The UE may determine a difference between the received signal levels for the two RATs, compare the difference against at least one threshold, and select a search rate associated with a range within which the difference falls as the rate of searches for the second RAT. In another aspect, the UE may control certain aspects of searches (e.g., determine whether or not to perform searches or the rate of searches) for the second RAT by considering the frequency bands for the two RATs.