Multi-RAT Cell Search Using Two-Phase Band Prioritization
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Solution Overview
Problem
User equipment (UE) experiences inefficient and energy-consuming cell searches due to reliance on outdated information about radio access technology (RAT) and frequency band deployments, leading to unnecessary scanning of descoped RATs and bands.
Innovation Solution
Implementing a two-phase specific band search (SBS) for UEs, where the first phase prioritizes known deployed bands and the second phase scans remaining bands, along with techniques to avoid descoped RATs and bands, using stored deployment information and current scenario-based search patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs a comprehensive specific band search across all possible bands for multiple RATs, then the cell search coverage is improved, but the energy consumption and search time increase significantly
Solution Approach 1:
The patent segments the cell search process into two distinct phases: Phase 1 performs a comprehensive search across all possible bands for all supported RATs to ensure complete coverage, while Phase 2 performs a targeted search only on bands where newer RATs (NR, LTE) are actually deployed based on stored deployment information. This segmentation allows the UE to balance between exhaustive coverage and energy-efficient operation by adapting the search scope to current network conditions.
2Loss of time
If the UE uses stored information from previous deployments to guide cell search, then the search time is reduced, but outdated information about descoped RATs leads to unsuccessful searches
Solution Approach 1:
The patent implements a dynamic cell search strategy where the UE adapts its search behavior based on the current phase and available information. In Phase 1, the UE performs exhaustive searches without relying on stored deployment information to ensure no cells are missed. In Phase 2, the UE dynamically utilizes stored PLMN deployment information to prioritize searches on bands where newer RATs are actually deployed, thereby reducing search time while maintaining reliability through adaptive decision-making.
3Reliability
If the UE scans all frequency bands for all supported RATs, then the probability of finding a deployed cell is improved, but the search complexity and processing load increase
Solution Approach 1:
The patent divides the complex multi-RAT cell search into two manageable phases with different complexity levels. Phase 1 handles the comprehensive search across all RATs and bands systematically, while Phase 2 simplifies the process by focusing only on newer RATs (NR, LTE) and their deployed bands using stored deployment information. This segmentation reduces processing complexity while maintaining high cell detection probability through the combination of exhaustive initial search and targeted follow-up search.
Data Source
AI summary
A user equipment (UE) configured to determine, for each radio access technology (RAT) of a plurality of RATs, a first list of bands on which a public land mobile network (PLMN) is expected to be deployed and a second list of bands including bands not included in the first list, wherein the first list is determined based on a region where the UE is currently located and PLMN deployment information, select a search pattern for performing a cell search based on a current UE scenario, perform a first phase of the cell search and when the first phase of the cell search is unsuccessful and no cell is selected, perform a second phase of the cell search by either scanning frequencies included in the second list of bands for the first priority RAT or scanning frequencies included in the first list of bands for a second priority RAT.