Network Handover Indication for Voice Service Return to NG RAN
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Solution Overview
Problem
Current next-generation radio access networks (NG RAN) fail to meet voice service coverage requirements, leading to terminal devices falling back to evolved universal terrestrial radio access networks (E-UTRAN) for voice services, with no efficient solution for quickly returning to NG RAN, resulting in suboptimal service experience and resource wastage.
Innovation Solution
A network handover method where an access network device of the NG RAN sends indication messages to the E-UTRAN to facilitate the terminal device's return to the NG RAN after voice service completion, using first and second indication information to manage the handover process, thereby reducing system signaling overheads and enabling better service utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If terminal device falls back to E-UTRAN for voice service, then voice service coverage requirement is met, but terminal device cannot quickly return to NG RAN resulting in service experience degradation
Solution Approach 1:
The core network device performs preliminary actions by determining that handover is due to voice call and by preparing return handover information before the terminal device completes its fallback to E-UTRAN. The AMF or MME proactively determines the handover cause and prepares the return path, enabling the terminal device to quickly return to NG RAN after voice service completion without prolonged camping on E-UTRAN.
2Ease of operation
If terminal device camps on E-UTRAN for voice service, then voice service is executed, but terminal device cannot make full use of higher-rate services provided by NG RAN
Solution Approach 1:
The system implements dynamic network selection by enabling the terminal device to switch between E-UTRAN and NG RAN based on service requirements. The terminal device dynamically camps on E-UTRAN for voice service execution and then dynamically returns to NG RAN for higher-rate services, optimizing service rate utilization while maintaining ease of voice service operation.
3Productivity
If handover indication information is sent between network devices, then terminal device can return to NG RAN, but system signaling overhead increases
Solution Approach 1:
The handover indication information is integrated into existing multi-functional signaling messages between network devices. The same signaling infrastructure used for initial handover and service setup is reused for return handover coordination, reducing additional signaling overhead while maintaining efficient handover execution. The core network device leverages existing message paths to convey return handover instructions.
Data Source
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AI summary
Embodiments of this application relate to the communications field and disclose a network handover method and a session management network element, so that a terminal device is returned to an NG RAN after the terminal device falls back to an E-UTRAN to execute a voice service. The network handover method includes: receiving, by an access network device of a first network, a first message from a core network device of the first network, sending a second message to the core network device of the first network, and sending a third message to the core network device of the first network or an access network device of a second network. The first message is used to request to set up a user plane tunnel of a voice service for a terminal device, the second message is used to respond to the first message, and the third message is used to trigger the terminal device to be handed over from the first network to the second network. At least one of the second message and the third message carries first indication information and/or second indication information, the first indication information is used to indicate that the terminal device is handed over from the first network to the second network to set up a voice service, and the second indication information indicates that the terminal device needs to return to the first network after the voice service ends.