Unified SRVCC and PS HO Signaling for LTE to CDMA Handover
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Solution Overview
Problem
Current mobility procedures between LTE and CDMA systems fail to provide simultaneous voice and data continuity during Single Radio Voice Call Continuity (SRVCC) and Packet Switched Handover (PS HO), leading to disruptions in data sessions when user equipment loses LTE coverage.
Innovation Solution
A new procedure is introduced where the eNB decides and communicates to the user equipment to perform simultaneous 1xRTT SRVCC and PS HO to CDMA systems, modifying signaling between the eNB and user equipment, and the MME is instructed not to suspend or deactivate bearers, ensuring session continuity for PS sessions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional separate SRVCC and PS HO procedures are used, then voice continuity can be maintained, but data sessions are disrupted when user equipment loses LTE coverage
Solution Approach 1:
The patent combines SRVCC and PS HO procedures into a single unified procedure. The eNB triggers both voice call handover to 1xRTT and packet data handover to HRPD simultaneously through integrated signaling messages (Handover Command and Handover Confirm), allowing user equipment to maintain both voice and data continuity while transitioning from LTE to CDMA systems.
2Reliability
If MME suspends or deactivates bearers during handover, then resource management is simplified, but session continuity for PS sessions is lost
Solution Approach 1:
The patent establishes data bearers to HRPD nodes before the handover is completed. The eNB configures data forwarding tunnels and sets up packet data paths in advance, ensuring that when the handover executes, data sessions continue without interruption. This preliminary setup of data paths resolves the contradiction between maintaining session continuity and simplifying bearer management.
3Reliability
If simultaneous 1xRTT SRVCC and PS HO to HRPD is implemented, then voice and data continuity are maintained, but signaling complexity between eNB and MME increases
Solution Approach 1:
The patent merges SRVCC and PS HO signaling into unified message exchanges. The Handover Command message from eNB to user equipment contains both voice handover instructions (1xRTT parameters) and data handover instructions (HRPD parameters). Similarly, the Handover Confirm message consolidates acknowledgments for both procedures, reducing the number of separate signaling transactions while maintaining full functionality.
Solution Approach 2:
The eNB performs multiple functions through a single signaling entity: it acts as both the SRVCC trigger node and the PS HO controller. The same signaling interface and message structures are used to coordinate both voice and data handovers, eliminating the need for separate signaling paths and reducing overall system complexity despite the enhanced functionality.
Data Source
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AI summary
Example embodiments presented herein are directed towards a base station, user equipment and Mobility Management Entity, and corresponding methods, for providing handling during a combined Single Radio Voice Call Continuity and Packet Switched Handover procedure.