PLMN Priority List for Cell Selection in Shared Radio Access Networks
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Solution Overview
Problem
In shared radio access networks, user equipment (UE) from different operators are treated differently based on their priorities, but existing systems do not allow for distinct priority settings for Public Land Mobile Networks (PLMNs) sharing the same cell, leading to UEs with lower priority camping on shared RANs despite better radio quality, which can result in unsatisfactory Quality of Service (QoS) for delay-sensitive services due to high load-induced blocking.
Innovation Solution
Radio base stations broadcast a PLMN list with priority indices, allowing UEs to differentiate between shared and dedicated networks and prioritize cell selection based on PLMN-specific priorities during cell selection or reselection, ensuring delay-sensitive UEs avoid shared RANs with lower priority unless no other options are available, and allowing traffic offloading by selecting shared RANs for delay-tolerant services when radio quality is better.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UEs select cells based on radio quality alone, then connection quality is improved, but lower priority UEs camp on shared RAN causing QoS degradation due to high load blocking
Solution Approach 1:
The patent changes the cell selection parameter from radio quality alone to a composite parameter that includes both radio quality and PLMN priority. The network broadcasts plmn-PriorityList indicating priority levels for different PLMNs, and UEs use this priority information alongside radio quality measurements to determine cell selection, ensuring higher priority PLMNs are protected from congestion while maintaining good connection quality
Solution Approach 2:
The patent applies different selection criteria to different PLMNs based on their priority levels. High priority PLMNs (such as public safety networks) are directed to dedicated RAN resources with guaranteed QoS, while lower priority PLMNs can utilize shared RAN resources when radio quality is good, creating localized quality differentiation across different operator networks
2Ease of operation
If UEs from lower priority operators camp on shared RAN with better radio quality, then connection establishment is improved, but network blocking increases for delay-sensitive services
Solution Approach 1:
The patent performs preliminary prioritization by broadcasting PLMN priority information in system information before UEs attempt cell selection. This allows UEs to pre-determine which cells are appropriate for their PLMN based on priority levels, preventing lower priority UEs from unnecessarily attempting to camp on shared RAN cells that could block delay-sensitive services, thus maintaining both ease of connection establishment and service reliability
3Reliability
If dedicated RAN is used for all UEs, then QoS for delay-sensitive services is improved, but network resource utilization efficiency deteriorates
Solution Approach 1:
The patent segments the network into dedicated RAN resources for high priority PLMNs and shared RAN resources for lower priority PLMNs. This segmentation allows critical delay-sensitive services to be isolated on dedicated resources with guaranteed QoS, while non-critical traffic can utilize shared resources, thereby maintaining both QoS guarantees and efficient resource utilization across the entire network
Data Source
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AI summary
Described are, among other things, methods and devices for cell selection or cell reselection in a UE, where the UE can connect to multiple radio access networks. The UE can receive a message indicating the priority of the Public Land Mobile Network that the UE belong to and performing cell selection / cell reselection based on the message.