UE Access Category Selection for Voice Call Prioritization
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Solution Overview
Problem
Current 5G NR technology faces challenges in prioritizing voice calls over packet-switched domains, leading to potential bottlenecks and service disruptions, especially when Access Category 7 is barred due to network congestion.
Innovation Solution
The UE selects a different access category for establishing PDU sessions for voice calls, such as Access Category 4 for MMTel voice calls, to ensure prioritization and avoid potential barring, using predefined mapping tables to determine the appropriate access category based on the intended network request.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If Access Category 7 is used for establishing PDU sessions for voice calls, then the access procedure is simplified, but voice calls are blocked when Access Category 7 is barred due to network congestion
Solution Approach 1:
The patent segments the access category selection process by creating separate access categories for different service types. Instead of using a single Access Category 7 for all data traffic, the patent divides it into general data access (AC7) and voice call access (AC4 or AC9), allowing voice calls to use dedicated categories that are less likely to be barred during congestion.
Solution Approach 2:
The patent introduces an intermediary mechanism - the access category mapping table - that translates voice call requests into appropriate access categories. This mapping table acts as a mediator between the voice call service requirement and the network access control mechanism, ensuring voice calls use prioritized categories.
2Device complexity
If a single access category is used for all data traffic, then the access control mechanism is simplified, but service prioritization cannot be achieved during network congestion
Solution Approach 1:
The patent implements dynamic access category selection based on the type of service being requested. The system dynamically maps different services (voice calls, data, signaling) to appropriate access categories, allowing the access control mechanism to adapt its behavior based on service requirements while maintaining a relatively simple overall structure.
Solution Approach 2:
The patent changes the access category parameter based on the service type. Instead of using a fixed access category for all traffic, the system modifies the access category parameter dynamically - using AC4 for MMTel voice calls, AC9 for IMS signaling, and AC7 for general data - thereby enabling service prioritization through parameter variation.
3Device complexity
If Access Category 7 is used for voice calls, then network resource allocation is simplified, but voice call quality deteriorates during network congestion
Solution Approach 1:
The patent applies local quality by assigning different access categories to different service types based on their specific requirements. Voice calls receive specialized access categories (AC4, AC9) with appropriate prioritization characteristics, while general data traffic uses AC7. This localized optimization ensures voice calls maintain quality during congestion without requiring complex global resource allocation changes.
Data Source
AI summary
A UE determines a need to access a network to establish a Protocol Data Unit (PDU) session for Internet Protocol (IP) Multimedia Subsystem (IMS) signaling or for a voice call over a packet-switched (PS) domain. The UE selects an access category for accessing the network. The selected access category is different from an access category for mobile-originated data. The UE attempts to access the network using the selected access category.