Inter-Core Network Handover via L2 Signaling
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Solution Overview
Problem
Current L2 and L3 handover schemes in packet-switched networks, such as UMTS and E-UMTS, face challenges with IP address mobility and suffer from long delays and packet loss during handovers between Core Network entities, particularly due to the lack of support for IP address mobility and inefficient use of IP control protocols.
Innovation Solution
A method and apparatus that enables fast and seamless handover between Core Network entities by using L2 signaling to manage IP address mobility, where the old RAN sends a handover message to the new RAN, which acquires a new IP address and includes it in a handover command message, allowing the UE to perform inter-RAN and inter-CN handovers efficiently.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional L3 handover procedures are used between Core Network entities, then handover can be performed, but long delays and large packet loss occur
Solution Approach 1:
The patent applies preliminary action by pre-establishing an IP tunnel between the old CN and new CN before the UE actually moves. The tunnel setup is performed in advance through signaling between RANs and CNs, so when handover occurs, data can immediately flow through the pre-established tunnel without waiting for IP address reconfiguration, thereby eliminating handover delays and packet loss.
2Adaptability or versatility
If traditional L3 handover procedures are used between Core Network entities, then handover can be performed, but IP address mobility is not supported
Solution Approach 1:
The patent segments the handover process into two independent parts: L2 handover (radio access layer) and L3 handover (network layer). By separating these layers, the UE can perform L2 handover to the new RAN while the L3 IP address mobility is handled independently through the pre-established tunnel between CNs. This segmentation allows IP address mobility to be supported without compromising handover reliability.
3Speed
If concurrent L2 and L3 handovers are performed, then fast seamless handover is achieved, but complex coordination between layers is required
Solution Approach 1:
The patent introduces the RAN as an intermediary that coordinates between L2 and L3 handover procedures. The RAN receives handover requirements from the UE, establishes the IP tunnel between CNs, and manages the timing of L2 and L3 handover execution. This intermediary role simplifies the coordination complexity by centralizing control in the RAN rather than requiring direct complex interactions between multiple network entities.
Data Source
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AI summary
A method and apparatus for performing an inter-RAN L2 handover and an inter-CN L3 handover in a packet-switched network are provided. When a UE connected to an old CN through the old RAN moves to a new RAN belonging to a new CN, an old RAN sends a handover required message to a new RAN. The new RAN acquires a new IP address for the UE from the new CN and sends a handover command message including the new IP address to the old RAN. The old RAN forwards the handover command message comprising an address of the new RAN to the UE. The UE performs an inter-RAN handover in response to the handover command message, to communicate with the old CN through the new RAN and performs an inter-CN handover based on the new IP address to communicate with the new CN through the new RAN.