Base Station RAT Change via Signal Quality Estimation
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Solution Overview
Problem
The process of changing Radio Access Technologies (RAT) in mobile terminals within communications networks is inefficient, often taking tens of seconds due to the lack of signal quality information about alternative RATs, leading to inferior accessibility and user perception issues, especially when LTE coverage is better than alternative RATs like UMTS or GSM.
Innovation Solution
A method at a base station to determine if a change from a serving RAT to a first target RAT is necessary, estimating the signal quality of the first target RAT based on the serving RAT's quality measure and instructing the mobile terminal to switch if the quality exceeds a threshold, thereby reducing setup times for voice calls or SMS by avoiding unnecessary measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the base station commands the UE to measure signal quality of alternative RATs before RAT change, then the RAT change decision accuracy is improved, but the call setup time increases significantly
Solution Approach 1:
The base station performs preliminary assessment of alternative RAT coverage and signal quality using available information (serving RAT quality, coverage maps, historical data) before commanding the UE to perform measurements. This preliminary action allows the base station to pre-determine the most suitable target RAT, so that when a call setup is requested, the UE can immediately switch to the pre-selected RAT without performing time-consuming measurements, thus resolving the contradiction between measurement accuracy and call setup time.
2Loss of time
If the base station performs blind RAT change without signal quality information, then the call setup time is reduced, but the RAT change decision accuracy deteriorates
Solution Approach 1:
The invention introduces coverage maps and quality threshold values as intermediary elements. The base station uses coverage maps (which contain pre-stored signal quality information for different RATs in various locations) and quality thresholds as mediators to make informed RAT change decisions. Instead of relying solely on real-time UE measurements or blind switching, the base station consults these intermediary data structures to determine the optimal target RAT, achieving both fast call setup and accurate decision-making.
3Measurement precision
If the base station uses coverage maps and quality thresholds to determine RAT change, then the RAT change decision accuracy is improved, but the device complexity increases
Solution Approach 1:
Coverage maps and quality threshold values are prepared in advance through network planning and measurements, stored in the base station's database. This preliminary action transforms complex real-time decision-making into simpler look-up operations. When a RAT change is needed, the base station simply queries the pre-computed coverage map with the UE's location and compares the result against quality thresholds, avoiding the need for complex real-time signal analysis and reducing processing complexity while maintaining high decision accuracy.
Data Source
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AI summary
The present invention relates to a method at a base station (10) of changing Radio Access Technology (RAT) of a mobile terminal (11) in a communications network, and a base station performing the method. The method according to an embodiment of the present invention comprises determining (S101) that a change is to be made from a serving RAT to a first target RAT, estimating (S102) a quality measure of the first target RAT based on a quality measure of the serving RAT, and instructing (S103) the mobile terminal to change to the first target RAT if the estimated signal quality measure of the first target RAT exceeds a quality threshold value.