Unified Access Control Parameter Update for 5G Congestion
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Solution Overview
Problem
The 5G system lacks procedures for invoking Unified Access Control (UAC) to mitigate congestion related to specific access categories, leading to potential service disruptions due to unmanaged traffic and signaling overload, and faces challenges in assigning unique operator-defined access categories due to limitations in existing specifications, which can result in network congestion and unauthorized access control.
Innovation Solution
A method for user equipment (UE) that involves receiving a NOTIFICATION message, determining the access category, checking access barring status, and sending a Radio Resource Control (RRC) connection setup request to a base station only when access is allowed, along with transmitting a SERVICE REQUEST message after establishing the RRC connection, to manage access control and congestion effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Unified Access Control (UAC) is implemented to manage access categories, then access control capability is improved, but device complexity increases due to multiple access categories and barring checks
Solution Approach 1:
The access control mechanism is segmented into distinct access categories (0-15) with specific meanings, allowing fine-grained control over different types of access attempts. Each category can be independently barred or allowed, enabling precise management of network access while maintaining organized complexity through structured segmentation.
Solution Approach 2:
The system changes the parameter of access category assignment dynamically. The AMF can assign different access categories to service request procedures based on network conditions, UE state, and service type. This parameter flexibility allows the system to adapt access control strictness without changing the fundamental mechanism structure.
2Productivity
If access barring checks are performed for all access categories, then network congestion is reduced, but signaling overhead increases due to additional check procedures
Solution Approach 1:
The system performs access barring checks selectively rather than universally. The UE checks access barring for the specific access category assigned to its service request procedure. This partial action approach applies congestion control only where needed for specific access categories while avoiding unnecessary signaling overhead for categories that are already allowed.
3Measurement precision
If operator-defined access categories are assigned uniquely for each S-NSSAI, DNN, APP ID and OSS ID combination, then access control precision is improved, but the number of access categories exceeds the limitation of 32 categories
Solution Approach 1:
The system merges multiple access control dimensions (S-NSSAI, DNN, APP ID, OSS ID) into a unified access category framework. Instead of creating separate categories for each combination, the AMF evaluates multiple criteria and assigns a single access category (0-15) that represents the combined state, thereby maintaining precision while respecting the 32-category limitation.
Solution Approach 2:
Each access category (0-15) is designed to be multi-functional, representing different combinations of S-NSSAI, DNN, APP ID, and OSS ID states. A single access category can serve multiple purposes depending on the UE's current configuration and network policies, allowing the limited 32 categories to cover a vast number of access control scenarios.
4Reliability
If the UE sends service request procedures for all PDU sessions when receiving NOTIFICATION message, then data delivery reliability is improved, but network congestion increases due to multiple simultaneous access attempts
Solution Approach 1:
The UE performs access control checks for only the specific PDU session indicated in the NOTIFICATION message rather than attempting to establish all possible PDU sessions. This partial action ensures reliable delivery for the targeted session while avoiding unnecessary access attempts that would contribute to network congestion.
Data Source
AI summary
A UE is in a connected mode over a non 3GPP access and in an idle mode over a 3GPP access. The UE receives a NOTIFICATION message from a core network node over the non-3GPP access. The UE determines, when performing a service request procedure, MT_acc=0 as an access category to be associated with the service request procedure upon receiving the NOTIFICATION message. The UE checks whether an access attempt for an access category is barred or allowed. When the access category is allowed, the UE sends a RRC connection setup request to a base station and transmits a SERVICE REQUEST message to the core network node after a RRC connection is established.