RRC Interworking in LTE-5G Radio Systems

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Solution Overview

Problem

Establishing smooth interworking between LTE and 5G systems in the RRC layer is challenging, particularly in scenarios like LTE assisted 5G and 5G assisted LTE, due to differences in radio resource control protocols and the need for seamless communication between radio base stations.

Innovation Solution

A radio communication system is designed with a first radio base station conforming to LTE and a second base station conforming to 5G, each equipped with specific RRC function units that operate based on their respective protocols, and an interworking unit that enables simultaneous operation and information exchange between them, allowing for active states and master roles within the RRC protocol.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If LTE and 5G systems use different RRC protocols for interworking, then each system can maintain its own protocol specifications and implementation independence, but establishing smooth interworking between the systems becomes difficult due to protocol incompatibility

Engineering Contradiction:
Improveprotocol independenceVSAvoidinterworking smoothness
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent introduces an intermediary mechanism where the 5G RRC protocol acts as a bridge between LTE and 5G systems. The 5G RRC protocol includes functional elements that can operate in both 5G and LTE contexts, enabling seamless interworking while maintaining protocol independence. Specifically, the 5G RRC protocol can initiate and manage LTE-assisted 5G operations, coordinating between the two systems without requiring LTE to understand 5G-specific protocol elements.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Ease of operation

If a single RRC protocol is used for both LTE and 5G, then protocol compatibility is improved, but the ability to implement advanced 5G-specific functions and maintain protocol evolution is reduced

Engineering Contradiction:
Improveprotocol compatibilityVSAvoid5G-specific function capability
Core Design Contradiction:
Ease of operationVSAdaptability or versatility

Solution Approach 1:

The patent segments the RRC protocol functionality into core common functions and 5G-specific advanced functions. The 5G RRC protocol is divided such that basic RRC functions can operate in LTE mode for compatibility, while 5G-specific functions (such as NR-specific configuration, 5G mobility management, and advanced features) are separated as optional extensions. This allows the protocol to maintain compatibility with LTE while enabling 5G-specific capabilities when needed.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a dynamic RRC protocol structure where the 5G RRC protocol can adaptively switch between LTE-compatible mode and 5G-optimized mode based on the operational context. The protocol includes dynamic configuration options that allow it to enable or disable 5G-specific functions depending on whether the system is operating in LTE-assisted 5G mode or pure 5G mode, providing both compatibility and advanced functionality as needed.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3457722B1Radio communication system
Publication Date: 2023.03.22 NTT DOCOMO INC
  • EP3457722B1 patent drawingFigure 1
  • EP3457722B1 patent drawingFigure 2~3
  • EP3457722B1 patent drawingFigure 4

AI summary

Provided are a radio communication system and user device that enable smooth interworking in a radio resource control (RRC) layer in the case of implementing interworking between systems by LTE assisted 5G, 5G assisted LTE, or the like. The radio communication system includes an eNB 100 conforming to LTE and a 5G-BS 200 conforming to 5G. The eNB 100 includes an RRC function unit 110 that performs control based on LTE-RRC, which is an RRC protocol in LTE. The 5G-BS 200 includes an RRC function unit 210 that performs control based on 5G-RRC, which is the RRC protocol in 5G. The RRC function unit 210 has at least a function not specified in LTE-RRC.