X2 Proxy Activation for Relay Node Mobility in LTE

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Solution Overview

Problem

In wireless cellular communication, especially in LTE-Advanced and high-speed railway scenarios, the existing X2 proxy architecture faces challenges in maintaining effective X2 message transmission when a relay node or a Home evolved Node B moves out of the initial Donor eNB's coverage, leading to reduced communication quality and user experience due to the absence of direct X2 interfaces with adjacent eNBs.

Innovation Solution

Implementing a method and system where a next-hop node serves as an X2 proxy for a previous-hop node, enabling X2 message interaction through multiple proxies, including activation instructions in X2 connection establishment, handover, and eNB configuration updates to ensure continuous X2 message transmission even when direct interfaces are absent.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a relay node moves out of the initial Donor eNB's coverage, then the relay node can continue to provide service to UEs, but direct X2 interface connection with adjacent eNBs is lost, causing X2 message transmission to fail

Engineering Contradiction:
Improverelay node mobility supportVSAvoidX2 message transmission reliability
Core Design Contradiction:
Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces an X2 proxy mechanism where the initial Donor eNB acts as an intermediary to forward X2 messages between the moved relay node and adjacent eNBs. When a relay node moves out of direct X2 interface range, the initial Donor eNB proxies the X2 signaling traffic, enabling continued message transmission without requiring direct physical interface connections. This resolves the contradiction by maintaining reliability through indirect routing while supporting relay node mobility.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Duration of action of stationary object

If multiple X2 proxies are deployed to support relay node mobility, then communication continuity is improved, but system complexity increases due to additional proxy nodes and message routing logic

Engineering Contradiction:
ImproveX2 message transmission continuityVSAvoidX2 proxy system complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The patent establishes X2 proxy relationships in advance before relay nodes move. The initial Donor eNB is pre-configured as an X2 proxy for its served relay nodes, and adjacent eNBs are pre-registered in the proxy relationship database. This preliminary setup enables seamless message forwarding when mobility occurs, reducing the need for complex real-time discovery and negotiation protocols, thereby limiting system complexity while maintaining continuity.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If direct X2 interfaces are established between all relay nodes and adjacent eNBs, then X2 message transmission is reliable, but network infrastructure complexity and interface management overhead increase

Engineering Contradiction:
ImproveX2 message transmission reliabilityVSAvoidX2 interface management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent makes the initial Donor eNB multi-functional by enabling it to serve both as a normal eNB with direct X2 interfaces and as an X2 proxy for moved relay nodes. This universal capability allows the network to use direct interfaces when available (for reliability) while falling back to proxy-based indirect interfaces when needed (to reduce complexity), optimizing the trade-off between reliability and complexity dynamically without requiring separate dedicated proxy infrastructure.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2953419B1Method and system for implementing x2 proxy
Publication Date: 2021.06.16 ZTE CORP
  • EP2953419B1 patent drawingFigure 1~2
  • EP2953419B1 patent drawingFigure 3~4
  • EP2953419B1 patent drawingFigure 5~6

AI summary

Disclosed are a method and system for implementing an X2 proxy. The method includes that a function of a next-hop node serving as an X2 proxy of a previous-hop node (300) is activated; and X2 message interaction between an initial node and a target node is implemented through more than one X2 proxy including the previous-hop node and the next-hop node (301).