SRVCC Capability Transmission via Core Network Relay
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Solution Overview
Problem
During inter-RAT handovers, voice call continuity is compromised due to the lack of SRVCC capability information when a terminal is handed over from a low-standard network to a high-standard network, as the low-standard network does not require SRVCC capability information, leading to incomplete SRVCC procedure initiation in the high-standard network.
Innovation Solution
The SRVCC capability information is proactively transmitted by the terminal to the CN network element during a TAU procedure and then sent by the CN network element to the RAN network element using a user equipment context modification request message, ensuring the RAN network element receives the necessary information to initiate an SRVCC procedure upon handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the terminal is handed over from a low-standard network to a high-standard network by inter-RAT handover, then the network coverage and service capability are improved, but the SRVCC capability information is lost and voice call continuity cannot be ensured
Solution Approach 1:
The patent applies preliminary action by having the terminal proactively report its SRVCC capability information to the CN network element before the handover is needed. This is achieved through the terminal sending an attach request or TAU request that includes SRVCC capability information to the CN network element, ensuring the information is available before the inter-RAT handover occurs.
Solution Approach 2:
The CN network element acts as an intermediary that receives, stores, and forwards the SRVCC capability information. The CN network element obtains the SRVCC capability information from the terminal and then sends it to the RAN network element, bridging the information gap between the terminal and the high-standard network's RAN element.
2Device complexity
If the low-standard network does not require SRVCC capability information, then the network complexity is reduced, but the SRVCC capability information is not transmitted to the high-standard network
Solution Approach 1:
The patent applies universality by making the CN network element serve multiple functions: it acts as both the serving network element for the terminal and as an information relay between the terminal and the RAN network element. The CN network element handles both standard mobility management and the additional function of SRVCC capability information management, eliminating the need for separate signaling mechanisms.
Solution Approach 2:
The terminal performs self-service by autonomously reporting its SRVCC capability information to the CN network element during standard procedures (attach or TAU). The terminal includes the SRVCC capability information in its uplink messages without requiring additional signaling procedures, allowing the information to be transmitted as part of normal network operations.
3Loss of energy
If the RAN network element cannot obtain SRVCC capability information, then the signaling overhead is reduced, but the SRVCC procedure cannot be initiated and voice experience is degraded
Solution Approach 1:
The patent applies merging by combining the SRVCC capability information transmission with existing standard signaling procedures. The SRVCC capability information is transmitted within the attach request or TAU request messages that are already part of normal network operations, rather than requiring separate dedicated signaling procedures. This reduces additional signaling overhead while ensuring reliable information delivery.
Data Source
AI summary
Embodiments of the present invention relate to the field of communications technologies, and disclose a single radio voice call continuity (SRVCC) capability information transmission method and apparatus, and a system. The method in the embodiments of the present invention includes: obtaining, by a core network (CN) network element, SRVCC capability information of a terminal from the terminal, where the terminal accesses, from a first-standard network by means of an inter-RAT handover, a second-standard network in which the CN network element is located, the first-standard network does not support an SRVCC function, and the second-standard network supports the SRVCC function; and sending, by the CN network element, the SRVCC capability information to a radio access network (RAN) network element.