RNC Neighbor-Cell List Filtering for Multi-Operator Handover

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Solution Overview

Problem

In multi-operator core networks, handovers between cells/base stations in shared radio access networks are prone to failure due to the core network's rejection of connections to unknown cells, leading to increased costs and reliability issues, especially when roaming subscribers attempt to handover to non-shared border cells.

Innovation Solution

The solution involves filtering neighbor-cell lists by instructing the Radio Network Controller (RNC) to exclude non-shared cells from the handover candidates based on the Iu-interface identity, ensuring that only shared cells are considered for handover, thereby reducing the risk of handover failure and improving reliability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the core network uses a comprehensive neighbor-cell list including all cells from multiple operators, then handover coverage is improved, but handover reliability deteriorates due to rejection of unknown cells

Engineering Contradiction:

Improvehandover coverageVSAvoidhandover reliability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The neighbor-cell list is segmented into operator-specific subsets. The RNC identifies which operator the UE belongs to and filters the neighbor-cell list to include only cells from that operator's network, preventing core network rejection while maintaining comprehensive coverage within the operator's domain.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The handover configuration is made local to each operator's network. Instead of a universal neighbor-cell list, each operator's UE receives a customized neighbor-cell list containing only relevant cells from its own operator, ensuring both reliability (by avoiding unknown cells) and coverage (by including all operator-specific cells).

Inventive Principle:

Principle #3Local quality

2Reliability

If special arrangements are made for roaming subscribers to handover to non-shared border cells, then handover reliability is improved, but device complexity and operational complexity increase

Engineering Contradiction:

Improvehandover reliability for roaming subscribersVSAvoidcomplexity of handover procedures

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The system performs self-service by automatically identifying the UE's operator affiliation and filtering the neighbor-cell list accordingly, without requiring manual configuration or special handling for roaming subscribers. The RNC autonomously determines which cells to include based on operator information already available in the system.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The same filtering mechanism serves all UEs regardless of whether they are roaming or home subscribers. The RNC uses a universal approach of operator-based filtering that works for all users, eliminating the need for separate special arrangements for roaming subscribers while maintaining high reliability.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS9967785B2Apparatus and methods for improved handover in multi-operator shared radio access network communications systems

Publication Date: 2018.05.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The present invention relates to handover in a communications system, and more especially it relates cell change using Iu-interface dependent neighbor-cell lists, particularly in a Universal Mobile Telecommunications System, UMTS or WCDMA system.