AMF Voice Handover from 5G PS to 2G CS Domain
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Solution Overview
Problem
There is a technical challenge in ensuring voice service continuity when a terminal moves out of the coverage area of a 5G network, as existing solutions do not effectively hand over voice services from the 5G network to the CS domain of 2G/3G networks, leading to potential service interruptions.
Innovation Solution
A communication method and apparatus that hand over voice services from a packet switched (PS) domain to a circuit switched (CS) domain, using key information derivation based on specific parameters such as function codes, downlink non-access stratum counts, and random numbers to ensure seamless continuity of voice services across different network generations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voice service is provided in 5G network using PS domain, then voice service quality is improved, but voice service continuity deteriorates when terminal moves out of coverage
Solution Approach 1:
The patent implements dynamic handover capability that allows the voice service to automatically transition between PS domain (5G/LTE) and CS domain (2G/3G) based on terminal location and network conditions. The system dynamically selects the appropriate domain for voice service delivery, ensuring continuity when moving between coverage areas.
Solution Approach 2:
The patent changes the network domain parameter from static PS domain only to dynamic selection between PS and CS domains. By modifying the domain parameter based on handover conditions, the system maintains voice service continuity while adapting to different network environments.
2Reliability
If handover from 5G network to CS domain is implemented, then voice service continuity is improved, but system complexity increases
Solution Approach 1:
The patent creates a universal handover mechanism that can operate across multiple network generations (5G, 4G, 3G, 2G) and domains (PS, CS). The same core handover logic handles transitions between different network types, reducing overall system complexity through standardized multi-functional processing.
Solution Approach 2:
The patent introduces a core network device as an intermediary that manages the handover process between the terminal and network. This mediator coordinates the complex interactions between PS and CS domains, simplifying the terminal's role and centralizing the complexity management in the network infrastructure.
3Reliability
If voice service is handed over to CS domain of 2G/3G network, then service continuity is improved, but network resource utilization deteriorates
Solution Approach 1:
The patent implements dynamic domain selection that keeps voice service in the more efficient PS domain (5G/LTE) when coverage is available, and only transitions to CS domain (2G/3G) when necessary for continuity. This dynamic approach optimizes resource utilization by preferring the more efficient domain while ensuring service continuity.
Solution Approach 2:
The patent changes the network domain parameter based on optimal resource utilization, selecting PS domain for better efficiency and CS domain only when required for continuity. This parameter optimization balances resource consumption with service reliability requirements.
Data Source
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AI summary
This application provides a communication method and a communications apparatus. The communication method includes: receiving, by an access and mobility management function AMF entity, a first message from an access network device, where the first message includes information for indicating to hand over a voice service of a terminal from a packet switched PS domain to a circuit switched CS domain, the first message further includes identification information of a target device, and the target device is an access network device in a 3G network and/or a 4G network; and deriving, by the AMF entity, key information of a network in which the target device is located. The technical solutions in the embodiments of this application can ensure continuity of the voice service and improve user experience.