Combined MRU List for 4G-5G Camping Latency
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Solution Overview
Problem
User Equipment (UE) experiences delays in camping on the best available cell when powered on or recovering from out-of-service mode, particularly in 5G and 4G overlapping areas, due to inefficient scanning methods that increase latency and delay in reporting higher priority PLMN to upper layers.
Innovation Solution
A method that creates a combined Most Recently Used (MRU) list merging 5G and 4G MRU frequencies, allowing parallel scanning and prioritizing cells with 5G Core, and performing full band scans in parallel to reduce camping time and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sequential scanning of 5G and 4G frequency bands is performed, then comprehensive cell coverage is achieved, but camping time and latency increase significantly
Solution Approach 1:
The patent combines 5G and 4G frequency band scanning into a unified parallel scanning process. The UE simultaneously scans both 5G MRU frequencies and 4G MRU frequencies (with 5GC) using the same receiver, merging what were previously sequential operations into concurrent execution. This reduces total scanning time while maintaining comprehensive cell coverage across both networks.
Solution Approach 2:
The patent implements dynamic scanning behavior where the UE adaptively switches between scanning 5G and 4G frequency bands based on real-time conditions. The scanning process is not static but dynamically adjusts which network to scan next, allowing the UE to optimize camping time by selecting the most promising network based on current signal conditions and availability.
2Reliability
If 5G full band scan is performed before 4G full band scan, then 5G cell priority is maintained, but overall latency increases
Solution Approach 1:
The patent performs partial scanning of frequency bands rather than complete full band scans. The UE scans MRU (Most Recently Used) frequencies first, which are the most likely to contain suitable cells, before proceeding to full band scans if necessary. This partial action approach maintains 5G priority while significantly reducing the time spent on exhaustive scanning of all frequencies.
Solution Approach 2:
The patent performs preliminary scanning of MRU frequencies in both 5G and 4G bands before initiating full band scans. By预先 scanning the most relevant frequencies first, the UE can often find suitable cells without needing to perform time-consuming full band scans, thus reducing overall latency while maintaining the ability to prioritize 5G when available.
3Measurement precision
If separate scanning of 5G and 4G MRU frequencies is performed sequentially, then thorough cell search is achieved, but camping efficiency decreases
Solution Approach 1:
The patent merges the separate scanning processes for 5G and 4G MRU frequencies into a single parallel scanning operation. The UE simultaneously processes both 5G MRU frequency lists and 4G MRU frequency lists (with 5GC support) using the same receiver, combining what were previously separate sequential operations into concurrent execution, thereby improving camping efficiency without sacrificing search thoroughness.
Data Source
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Figure 3B
AI summary
Various embodiments herein disclose a method camping a User Equipment (UE) on a cell, the method comprising: creating a combined Most Recently Used (MRU) list by merging a list 4G MRU frequencies with a Public Land Mobile Network (PLMN) having a 5GC and a list of 5G MRU frequencies, determining whether one of a 4G cell with 5G core (5GC) and a 5G cell is available for camping by performing a MRU scan on the combined MRU list; performing one of: camping on one of the 4G cell with 5G core and the 5G cell in response to determining that one of the 5G cell and the 4G cell with 5G core is available and performing a 4G MRU frequency scan on a list of 4G without 5GC MRU frequencies in response to determining that one of the 4G cell with 5G core and the 5G cell is not available.