Voice Service Handover via SRVCC Capability Detection
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Solution Overview
Problem
In scenarios where a terminal device is handed over from a 5G network to an LTE network, the core network device in the 5G network cannot determine if the terminal device supports single radio voice call continuity (SRVCC) from the LTE network to 2G/3G networks, leading to potential call failures and poor user experience.
Innovation Solution
A communication method where a mobility management network element in the LTE network suspends the initiation of a bearer setup for a voice service until it determines that a fallback to a 2G/3G network is supported, allowing the access network element to learn about the SRVCC capability and hand over the terminal device to a 2G/3G network if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the core network device in the 5G network immediately transfers bearer setup requests to the LTE network during handover, then the handover speed is improved, but the call continuity cannot be guaranteed because the SRVCC capability information is not yet available
Solution Approach 1:
The patent applies preliminary action by having the mobility management network element proactively send indication information about SRVCC capability support to the access network element before the bearer setup request is transferred. This advance notification allows the access network to prepare for potential voice service handover to 2G/3G networks, ensuring call continuity is maintained while preserving fast handover performance.
2Device complexity
If the access network element in the LTE network does not have SRVCC capability information, then the network complexity is reduced, but the voice service handover to 2G/3G networks cannot be performed, causing call failure
Solution Approach 1:
The patent uses an intermediary approach by introducing a mobility management network element that acts as a mediator between the 5G core network and the LTE access network. This intermediary collects and manages the SRVCC capability information and transfers it to the appropriate network elements, enabling voice service continuity without requiring complex modifications to the access network elements themselves.
3Reliability
If the mobility management network element sends indication information about SRVCC support before bearer setup, then the call continuity is improved, but the signaling delay increases
Solution Approach 1:
The patent merges the indication information about SRVCC capability support with the existing bearer setup request signaling flow. By combining these messages, the patent avoids additional separate signaling exchanges, thereby reducing signaling delay while still ensuring that the access network element receives the necessary capability information before bearer setup to maintain call continuity.
Data Source
AI summary
This application provides a communication method, apparatus, and system for a voice service. The method includes: A session management network element determines that a terminal device is to be handed over from a first network to a second network. The session management network element waits until a first moment to send a request message to a mobility management network element in the second network, where the request message is used to request to set up a first bearer for a voice service of the terminal device.