L3 Handover Between Core Network Entities in Packet-Switched Networks
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Solution Overview
Problem
Current 3G mobile communication systems face challenges in performing fast and seamless handovers between radio access networks (RANs) belonging to different Core Network (CN) entities in packet-switched networks, which hinders efficient data transmission and user equipment (UE) mobility.
Innovation Solution
A method and apparatus that enable fast and seamless handover by having the UE send a measurement report message to the old RAN, determining the need for Layer 3 (L3) handover, establishing a tunnel between the new RAN and new CN without the old CN, and acquiring a new IP address for communication through the new RAN, thereby simplifying the handover process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional L2 handover procedures are followed between RANs belonging to different CN entities, then connection reliability is maintained, but handover time and complexity increase
Solution Approach 1:
The patent segments the handover process into two distinct phases: L2 handover (radio access layer) and L3 handover (core network layer). By separating these phases, the system can perform L2 handover quickly while deferring L3 handover to occur asynchronously in the background, thus reducing overall handover time while maintaining connection reliability through the structured two-phase approach.
Solution Approach 2:
The patent performs preliminary L2 handover actions (establishing radio connection with new RAN) before completing L3 handover (core network entity migration). This preliminary action allows the UE to maintain continuous connectivity through the new RAN while the more time-consuming L3 handover procedures are executed in the background, effectively reducing perceived handover time.
2Reliability
If traditional inter-CN handover procedures are followed, then seamless connectivity is maintained, but device complexity and resource consumption increase
Solution Approach 1:
The patent divides the complex inter-CN handover procedure into separate L2 and L3 phases with distinct responsibilities. The L2 phase handles radio access connectivity while the L3 phase handles core network entity migration. This segmentation reduces device complexity by allowing independent optimization of each phase and reducing the coordination overhead between different network layers.
Solution Approach 2:
The patent introduces an intermediary mechanism where the new RAN acts as a bridge during the handover process. The new RAN receives and forwards data packets during the transition period, enabling seamless connectivity while the L3 handover procedures are being executed. This intermediary approach simplifies the overall handover complexity by providing a clear data path during the transition.
3Stability of the object's composition
If full L2 handover procedures are executed, then connection stability is ensured, but handover speed decreases
Solution Approach 1:
The patent implements a dynamic handover approach where L2 and L3 handover procedures can execute at different speeds and timescales. The L2 handover proceeds quickly to establish immediate radio connectivity, while L3 handover proceeds asynchronously in the background. This dynamic separation allows the system to optimize for speed in the critical L2 phase while maintaining stability through the more thorough L3 phase.
Solution Approach 2:
The patent ensures continuity of useful action by maintaining data transmission through the new RAN during the L3 handover process. Data packets are forwarded through the new RAN even before L3 handover completion, ensuring continuous connectivity and stability while enabling fast L2 handover execution.
Data Source
AI summary
A method and apparatus for performing a L3 handover between CNs in a packet-switched network are provided. When a UE moves from an old RAN to a new RAN, the UE sends a measurement report message including cell information to the old RAN. The old or new RAN determines whether to perform a L3 handover. If the L3 handover is required, a tunnel is established between the new RAN and a new CN. The UE performs a handover from the old RAN to the new RAN, without establishing a tunnel between the new RAN and an old CN. Upon detection of the movement of the UE, the new RAN sends a L2 handover complete message to the old RAN. After moving to the new RAN, the UE acquires a new IP address, performs the L3 handover, and communicates with the new CN through the new RAN.