SR-VCC Bearer Splitting for Seamless 4G to 3G Handover
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Solution Overview
Problem
Current technologies fail to achieve seamless voice call continuity between different radio access networks, particularly from 4G packet switched systems to 3G or 2G circuit switched systems without interruption, and lack co-existence solutions for VoIP capable GERAN/UTRAN networks.
Innovation Solution
A method and node for performing bearer splitting in communication systems, separating voice bearers from non-voice bearers based on dual transfer mode and packet switched handover support, enabling co-existence of single radio voice call continuity solutions between packet switched and circuit switched networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dual radio connection is used for voice call continuity during handover, then voice continuity between EUTRAN and GERAN/UTRAN CS domain is achieved, but it is not possible between EUTRAN and GERAN CS or EUTRAN and UTRAN CS due to radio compatibility constraints
Solution Approach 1:
The patent segments the bearer traffic into voice bearers and non-voice bearers. Voice bearers are separated and handled through circuit switched domain while non-voice bearers continue through packet switched domain. This segmentation allows the system to achieve voice continuity requirements without requiring dual radio capability, as only the voice traffic needs to be transferred to CS domain.
Solution Approach 2:
The patent introduces an intermediary node (such as SGSN or GGSN) that performs bearer splitting and coordination between PS and CS domains. This intermediary enables the handover process by managing the separation of voice and non-voice bearers, allowing EUTRAN to connect to GERAN/UTRAN CS domain without requiring direct dual radio support between incompatible radio access networks.
2Reliability
If bearer splitting is performed to separate voice and non-voice bearers, then single radio voice call continuity is achieved, but device complexity increases due to additional network entities and signaling requirements
Solution Approach 1:
The patent makes existing network entities (SGSN, GGSN, MSC) perform multiple functions. These entities not only handle their traditional packet switched or circuit switched functions but also perform bearer splitting, voice bearer identification, and coordination between domains. This multi-functionality reduces the need for dedicated new network entities, thereby limiting the increase in device complexity.
3Ease of manufacture
If existing network infrastructure is used without enhancements, then deployment cost is reduced, but co-existence of C-VCC and inter-MSC HO solutions cannot be achieved
Solution Approach 1:
The patent introduces dynamic selection capability where the network can choose between C-VCC and inter-MSC HO solutions based on real-time conditions, network configuration, and target cell capabilities. This dynamic approach allows the system to adapt to different deployment scenarios and network states, enabling co-existence of multiple solutions without requiring separate dedicated infrastructures for each approach.
Data Source
AI summary
The present invention discloses a node (207, 217) for achieving co-existence of single radio voice call continuity, SR-VCC, solutions in a communication system between a source cell of a first radio access network that supports packet switched voice and a target cell of a second radio access network that supports at least circuit switched voice. The node (207, 217) is operable to perform bearer splitting by separating voice bearers from non-voice bearers based on information about support for dual transfer mode, packet switched handovers and voice over internet protocol related enhancements in the target cell.