Inter-RAT Mobility Enhancement via Cached Cell Data
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Solution Overview
Problem
In mobile communications, inter-radio access technology (inter-RAT) mobility often results in difficulties for user equipment (UE) to efficiently transition between different radio access technologies, such as from LTE to legacy systems like GSM or UMTS, due to lack of LTE cell information provided by legacy systems, leading to prolonged camping times and failed returns to the original RAT.
Innovation Solution
A method and device that camp on a first RAT, measure and collect cell information during a second service on a different RAT, and determine the optimal cell to return to based on collected data after the second service is completed, allowing for quicker reconnection to the first RAT without relying on network-provided cell information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a UE falls back to a legacy system (second RAT) from LTE (first RAT), then the UE can perform services supported by the legacy system, but the UE cannot efficiently return to LTE due to lack of LTE cell information provided by the legacy system
Solution Approach 1:
The UE performs measurement and collection of first RAT (LTE) cell information while camped on the second RAT (legacy system). This preliminary action ensures that when the UE needs to return to LTE, it already has the necessary cell information cached, eliminating the need for lengthy PLMN searches and enabling quick return to the original RAT.
2Reliability
If a UE performs a PLMN search to return to the original RAT after falling back, then the UE can find a cell to camp on, but the process takes a lot of time and may fail
Solution Approach 1:
The UE caches first RAT cell information during the period it is camped on the second RAT. This preliminary measurement and storage of cell information eliminates the need for time-consuming PLMN searches when returning to the original RAT, significantly reducing camping time and improving return reliability.
Solution Approach 2:
The UE creates a copy of the first RAT cell information (measurement data, cell identifiers, frequency information) while on the second RAT and stores it locally. This copied information serves as a reference for quick cell selection when returning to the first RAT, avoiding the need to perform complete cell searches.
3Productivity
If the UE continuously measures and collects cell information of the first RAT while on the second RAT, then the UE can quickly return to the first RAT, but the UE consumes additional energy and processing resources
Solution Approach 1:
The UE performs measurement and collection of first RAT cell information periodically or at specific events while camped on the second RAT, rather than continuously. This periodic action reduces energy consumption and processing overhead while still maintaining sufficient cell information for efficient return to the original RAT when needed.
Data Source
AI summary
A method for inter-radio access technology (inter-RAT) performance enhancement in a mobile communications device is provided. First, a first RAT is camped on to perform a first service. Thereafter, it is moved/fallen back to a second RAT from the first RAT to perform a second service. Cell information of the first RAT is then measured and collected during the performance of the second service in the second RAT. A first cell to return to the first RAT is determined according to the collected cell information of the first RAT after a call connection of the second RAT is released.