CS Control Node RAN Selection Criteria for UE Re-Selection

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Solution Overview

Problem

Existing solutions for seamless handover and fast return to LTE networks in mixed 2G, 3G, and 4G environments are complex, require significant RAN node upgrades, and are limited by specific UE hardware and single-frequency selection criteria, making them impractical for widespread deployment.

Innovation Solution

A method where a CS control node determines and sends RAN selection criteria to a UE for re-selection after a CS service is terminated, allowing the UE to consider these criteria for choosing a preferred RAN, such as LTE, without impacting existing RAN nodes and supporting various UE hardware.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If existing solutions for seamless handover and fast return to LTE networks are implemented, then service continuity is improved, but device complexity and RAN node upgrade requirements increase significantly

Engineering Contradiction:

Improveservice continuityVSAvoidRAN node upgrade requirements

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent extracts the RAN selection criteria determination function from the complex RAN node infrastructure and relocates it to the CS control node. This extraction eliminates the need for upgrading numerous RAN nodes while maintaining service continuity, as the CS control node independently determines and provides selection criteria to the UE without requiring modifications to the RAN node architecture.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent segments the handover control functionality by separating the selection criteria determination (performed by the CS control node) from the execution (performed by the UE). This segmentation allows the core network to manage handover logic independently from the access network, reducing the complexity burden on RAN nodes while ensuring reliable service continuity.

Inventive Principle:

Principle #1Segmentation

2Speed

If RAN node upgrades are performed to enable fast return to LTE, then re-selection speed is improved, but manufacturing cost and deployment difficulty increase

Engineering Contradiction:

Improvere-selection speedVSAvoiddeployment difficulty

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The patent enables the UE to perform self-service in the handover process by providing it with RAN selection criteria from the CS control node. The UE autonomously selects the target RAN based on these criteria without requiring external control or upgrades to RAN nodes, thereby achieving fast re-selection while avoiding deployment complexity and costs associated with RAN node modifications.

Inventive Principle:

Principle #25Self-service

Solution Approach 2:

The CS control node performs preliminary action by determining and providing RAN selection criteria to the UE before the actual handover occurs. This advance preparation enables the UE to execute fast re-selection to the preferred RAN immediately when needed, without requiring real-time complex processing or upgraded RAN node capabilities.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If specific UE hardware limitations are accepted, then device compatibility is improved, but adaptability to different RAN configurations decreases

Engineering Contradiction:

ImproveRAN selection flexibilityVSAvoidUE hardware requirements

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent changes the approach from hardware-dependent RAN selection to parameter-driven selection. The CS control node provides selection criteria as configurable parameters (such as frequency, cell ID, or RAN type preferences) that the UE applies during handover. This parameter-based approach enhances adaptability to different RAN configurations without requiring complex or specialized UE hardware capabilities.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS10172057B2Handling of radio access network re-selection

Publication Date: 2019.01.01 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

A system, method, node and computer program for handling re-selection of a RAN (120, 130, 140) by a UE (100) is described. The UE (100) is attached via a first RAN (120, 130) to a CS control node (110) for execution of a CS service. The method comprises that the CS control node (110) receives an indication that the execution of the CS service shall be terminated. The CS control node (110) then determines whether the UE (100) shall perform re-selection of the RAN (120, 130, 140). If so, the CS control node (110) determines selection criteria for the re-selection of the RAN (120, 130, 140) and sends them to the UE (100) using Non-Access Stratum related signaling. The UE (100) receives the determined selection criteria from the CS control node (110) and re-selects the RAN (120, 130, 140), considering the received selection criteria.