LTE Handover Failure Recovery Using Physical Cell Identifier Mapping
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Solution Overview
Problem
In LTE networks, User Equipment (UE) cannot acquire the cell global identifier (ECGI) of the target cell during handover failures, preventing base stations from accurately judging handover situations and optimizing handover parameters.
Innovation Solution
The UE sends a physical identifier of the second cell to a network element connected to the first cell, which then forwards this information to the base station, allowing for accurate judgment of handover situations by using routing and addressing information to ensure successful identification of the second cell, even without a direct X2 interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the UE sends only the physical identifier of the second cell, then the information transmission is simple and fast, but the base station cannot accurately identify the second cell without ECGI
Solution Approach 1:
The patent introduces a mapping relationship between physical identifiers and ECGI as an intermediary mechanism. The network element stores and manages the correspondence between physical cell identifiers and ECGI, enabling the base station to translate the received physical identifier into the corresponding ECGI for accurate cell identification, thus resolving the contradiction between fast transmission and accurate identification
Solution Approach 2:
The patent creates a virtual copy of the ECGI information through the physical identifier. Instead of transmitting the actual ECGI, the system uses the physical identifier as a reference copy that can be converted back to ECGI through the mapping relationship, achieving accurate cell identification without direct transmission of the global identifier
2Measurement precision
If the network element stores mapping relationships for all cells, then accurate cell identification is achieved, but the network element complexity increases
Solution Approach 1:
The patent applies local quality by implementing the mapping relationship storage in a distributed manner across multiple network elements rather than centralizing it. Each network element maintains local mapping information relevant to its jurisdiction, reducing the complexity burden on any single element while collectively achieving comprehensive cell identification capability
Solution Approach 2:
The patent segments the large-scale cell identification task into smaller manageable units by dividing the mapping relationships across different network elements. Each network element handles a subset of the mapping data, allowing parallel processing and reducing the complexity load on individual components
3Productivity
If the UE performs RRC re-establishment in the first cell, then the handover failure is handled quickly, but the handover situation cannot be accurately judged without ECGI of the second cell
Solution Approach 1:
The patent implements a feedback mechanism where the physical identifier of the second cell is transmitted back to the base station after the UE performs RRC re-establishment. This feedback enables the base station to retrieve the corresponding ECGI through the mapping relationship, allowing accurate judgment of the handover situation while maintaining quick recovery through immediate re-establishment
Data Source
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AI summary
Disclosed are a processing method for handover failure and user equipment. The method comprises as follows: the user equipment fails to switch from a first cell to a second cell; the user equipment fails to re-establish radio resource control in the first, the second or a third cell, and succeeds in establishing radio resource control in a fourth cell; a network element to which the user equipment in a connected state is connected sends a physical identifier of the second cell to a network element to which the first cell belongs. The present invention can ensure that the network element to which the first cell belongs carries out accurate judgment of handover situations according to the physical identifier, which in turn can ensure the optimization of handover parameters.