Relay UE Connection Establishment for Remote UEs

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Solution Overview

Problem

Existing methods for establishing an RRC connection between a remote UE and a network are not applicable when the remote UE is out of coverage, and even when in coverage, using a direct connection can be inefficient due to potential poor coverage and increased interference.

Innovation Solution

A method of connection establishment through a relay UE for a remote UE, where the remote UE is in RRC_IDLE state and the relay UE is in RRC_CONNECTED state, involving discovery, establishment of a PC5-RRC connection, configuration of PC5 RLC channels for relaying, and subsequent security establishment and configuration of additional data radio bearers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If direct RRC connection establishment method is used between gNB and remote UE, then the connection can be established through standard procedure, but it is not applicable when remote UE is out of coverage and causes increased interference and capacity consumption when coverage is poor

Engineering Contradiction:

Improveapplicability in out-of-coverage scenariosVSAvoidinterference and capacity consumption

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a relay UE as an intermediary device between the remote UE and the network. The relay UE establishes a PC5-RRC connection with the remote UE and forwards RRC setup requests and responses through the Uu interface to the gNB, enabling out-of-coverage UEs to access the network without direct Uu interface connection, thereby reducing interference and capacity consumption on the air interface

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If relay UE is used for connection establishment, then coverage extension and interference reduction are achieved, but the connection establishment procedure becomes more complex

Engineering Contradiction:

Improveconnection establishment reliabilityVSAvoidconnection establishment procedure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the connection establishment procedure into distinct phases: (1) PC5-RRC connection establishment between relay UE and remote UE, (2) relay UE forwarding RRC setup request to gNB via Uu interface, (3) gNB sending RRC setup response through relay UE to remote UE, and (4) configuration of PC5 RLC channels for data relaying. This segmentation makes the complex procedure more manageable and implementable

Inventive Principle:

Principle #1Segmentation

3Ease of operation

If layer 2 relaying architecture is used, then RRC connection can be established through relay, but additional configuration of PC5 RLC channels and security establishment is required

Engineering Contradiction:

Improvesingle common procedure for connection establishmentVSAvoidconfiguration of PC5 RLC channels and security

Core Design Contradiction:

Ease of operationVSDevice complexity

Solution Approach 1:

The patent makes the relay UE capable of handling multiple functions: establishing PC5-RRC connection, forwarding RRC setup requests and responses, configuring PC5 RLC channels for both SRB1 and DRBs, and managing security establishment. This multi-functionality allows a single common procedure to handle both control plane and user plane relaying

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12219625B2Connection establishment for layer 2 UE-to-network relay

Publication Date: 2025.02.04 MEDIATEK SINGAPORE PTE LTD

AI summary

A method of connection establishment through a relay UE for a remote UE is proposed. The remote and relay UEs first perform discovery and establish a PC5 radio resource control (PC5-RRC) connection. Upon receiving a request from the remote UE, the relay UE and a serving gNB perform a relaying procedure for establishment of the remote UE's signalling radio bearer 1 (SRB1). The relay UE configures PC5 RLC channels for relaying of SRB1 towards the remote UE. The remote UE then enters an RRC_CONNECTED state. The remote UE and gNB establish security. The gNB configures additional data radio bearers (DRBs) for relaying. The relay UE configures PC5 RLC channels for relaying of the additional DRBs towards the remote UE. The DRBs can then be used for exchange of data between the remote UE and the gNB.