UE Cell Search Across Multi-RAT Bands With Two-Phase Scanning
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Solution Overview
Problem
User equipment (UE) experiences inefficiencies and increased energy consumption during cell search due to reliance on outdated information about radio access technology (RAT) and frequency band deployments, leading to unnecessary scanning of descoped RATs and bands.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
The UE performs a two-phase specific band search (SBS) that prioritizes known deployed bands in the first phase and scans remaining bands in the second phase, with optional exclusion of descoped RATs and bands based on current deployment information and scenario-specific search patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE performs a comprehensive specific band search scanning all possible bands for multiple RATs, then the cell search coverage is improved, but the time and energy consumption increases significantly
Solution Approach 1:
The patent segments the cell search process into two distinct phases: Phase 1 scans only the first list of bands (expected PLMN deployments) for the first priority RAT, while Phase 2 scans the second list of bands (remaining bands) for the first priority RAT or first list of bands for the second priority RAT. This segmentation allows the UE to perform a comprehensive search without treating it as a single exhaustive process, enabling optimization at each phase and reducing overall time consumption while maintaining complete coverage.
Solution Approach 2:
The patent applies preliminary action by performing Phase 1 of the cell search first, scanning only the first list of bands for the first priority RAT before proceeding to Phase 2. This preliminary scan of the most likely deployment bands allows the UE to quickly identify cells in common scenarios, and only if Phase 1 is unsuccessful does the UE proceed to the more time-consuming Phase 2 search, thereby reducing average search time while maintaining reliability.
2Reliability
If the UE scans all possible bands for multiple RATs, then the cell search completeness is improved, but the energy consumption increases
Solution Approach 1:
The patent segments the energy-intensive band scanning process into two phases with different scope and priority. Phase 1 focuses energy consumption on scanning only the first list of bands for the first priority RAT, which covers the most likely successful scenarios. Phase 2 scans the second list of bands or first list for alternative RATs only if Phase 1 fails. This segmentation ensures complete search coverage is maintained while significantly reducing average energy consumption by avoiding unnecessary scanning in many cases.
Solution Approach 2:
The patent performs the energy-efficient Phase 1 scan as a preliminary action before the more energy-consuming Phase 2 scan. By first scanning only the first list of bands for the first priority RAT, the UE can quickly determine success or failure with minimal energy expenditure. Only when Phase 1 is unsuccessful does the UE proceed to Phase 2, ensuring that the comprehensive but energy-intensive search is performed only when absolutely necessary, thereby maintaining completeness while optimizing energy usage.
3Speed
If the UE uses stored information for cell selection, then the cell search speed is improved, but the accuracy decreases when deployment information is outdated
Solution Approach 1:
The patent uses stored information to prepare the first list of bands and second list of bands in advance, which represents preliminary action. During cell search, the UE first scans the first list of bands (Phase 1) based on this pre-prepared information, achieving fast initial search. If Phase 1 fails, the UE proceeds to Phase 2 which scans the second list of bands, ensuring that even if the stored information is partially outdated, the UE can still find cells by exhaustively searching the remaining bands. This approach maintains both speed (through pre-prepared lists and phased scanning) and accuracy (through fallback to complete search).
4Reliability
If the UE performs phase 2 search scanning the second list of bands for the first priority RAT, then the search thoroughness is improved, but the time consumption increases
Solution Approach 1:
The patent applies dynamics by making the Phase 2 search behavior adaptive based on the search pattern selected. The UE can choose between two Phase 2 options: scanning the second list of bands for the first priority RAT, or scanning the first list of bands for the second priority RAT. This dynamic selection allows the system to adjust the thoroughness and time consumption of Phase 2 based on current needs, balancing reliability and time efficiency by choosing the appropriate search strategy for each situation.
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.