Multi-RAT RRC Connection Setup Using Reused Context

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Solution Overview

Problem

Existing wireless communication systems face high signaling load and delays when transitioning a user equipment (UE) from one Radio Access Technology (RAT) to another, leading to potential call drops and inefficient RRC connection management.

Innovation Solution

The system enables a UE to maintain simultaneous RRC connections with two different RATs by reusing context information from an existing connection, facilitating a light-weight RRC connection setup process, thereby reducing signaling load and enhancing connection establishment efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a UE releases RRC connection in source RAT and establishes new RRC connection in target RAT during RAT transition, then the UE can maintain proper connection management, but the signaling load increases and connection delays occur

Engineering Contradiction:

Improveconnection managementVSAvoidconnection establishment delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The target RAT node retrieves context information from the source RAT node before the UE completes the full RRC connection establishment. This preliminary retrieval of context data (including security information, bearer configurations, and UE capabilities) allows the target node to prepare connection parameters in advance, significantly reducing the time required for connection establishment while ensuring proper connection management.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

Instead of establishing a completely new RRC connection from scratch, the system copies relevant context information from the source RAT connection to the target RAT connection. The target node retrieves and utilizes the source node's context data (UE capabilities, security context, bearer information) to rapidly establish the new connection, avoiding redundant signaling while maintaining connection integrity.

Inventive Principle:

Principle #26Copying

2Reliability

Engineering Contradiction:

Improveconnection managementVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The invention extracts and retrieves only the essential context information from the source RAT node that is needed for connection establishment, rather than transferring all possible data. The target node selectively retrieves context data (UE capabilities, security context, bearer information) through efficient signaling, reducing the overall signaling overhead while ensuring proper connection management.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The context information retrieval is performed as a preliminary action before the full RRC connection establishment signaling sequence. By fetching necessary context data in advance through optimized signaling between network nodes, the system reduces the total amount of signaling required during the actual connection establishment, thereby reducing overall signaling overhead.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If separate Core Networks are introduced for different RATs, then each RAT can be independently managed, but the complexity of RAT transition increases and call drops risk increases

Engineering Contradiction:

ImproveRAT independent managementVSAvoidRAT transition complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The invention introduces an intermediary context retrieval mechanism between the source and target RAT nodes that facilitates smooth transitions while maintaining independent Core Network management. The target RAT node acts as an intermediary that retrieves necessary context information from the source RAT node, enabling coordinated transition management without requiring integrated Core Networks, thus reducing transition complexity while preserving RAT independence.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3384724B1Light-weight RRC connection setup in multi-rat network

Publication Date: 2026.03.04 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

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AI summary

The present disclosure generally relates to the field of Radio Resource Control (RRC). More specifically, the present disclosure relates to techniques of supporting and initiating RRC connection establishment in a wireless communication network. A method embodiment relates to supporting RRC connection establishment in a wireless communication network and comprises setting up context information during a first RRC connection establishment procedure to establish a first RRC connection towards a radio access network element (200) of the wireless communication network implementing a first Radio Access Technology (RAT). The context information is associated with a wireless communication device (100) of the wireless communication network and is usable for a second RRC connection establishment procedure to establish a second RRC connection towards a radio access network element of the wireless communication network implementing a second RAT.