Indirect-to-Indirect Path Switching in Layer 2 UE-to-Network Relay
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Solution Overview
Problem
In 5G new radio (NR) wireless communications, layer 2 UE-to-Network relaying environments face challenges in maintaining service continuity during indirect-to-indirect path switches, particularly when a remote UE needs to switch from one relay UE to another due to changing radio conditions or mobility, leading to potential service interruptions.
Innovation Solution
An indirect-to-indirect path switching procedure is implemented, where a remote UE is reconfigured to switch its service from a first relay UE to a second relay UE through a network node, using RRC reconfiguration messages to manage the transition without interrupting user services, ensuring seamless handover by maintaining protocol stack states and adapting sidelink and Uu interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a remote UE switches from a first relay UE to a second relay UE in a layer 2 UE-to-network relaying environment, then the service quality can be improved by selecting a better relay UE, but service continuity is interrupted during the path switch operation
Solution Approach 1:
The network node prepares the second relay UE before the actual path switch by establishing the necessary protocol stack states and configuration in advance. This preliminary preparation ensures that when the path switch is executed, the second relay UE is already ready to receive and forward data immediately, minimizing service interruption time.
Solution Approach 2:
The network node acts as an intermediary that coordinates the path switch between the remote UE and the relay UEs. It manages the transition by controlling the protocol stack states, coordinating the release of the first relay UE connection and establishment of the second relay UE connection, thereby enabling seamless handover.
2Adaptability or versatility
If the path switch operation is performed in a layer 2 relay architecture, then the relaying relationship can be flexible and adaptive, but the complexity of managing protocol stack states and service continuity increases
Solution Approach 1:
The network node serves as an intermediary that manages the protocol stack states between the remote UE and relay UEs. It handles the complexity by coordinating the PDCP layer state management, controlling the transition between different relay UEs, and ensuring proper protocol stack configuration, thereby reducing the burden on the relay UEs themselves.
Solution Approach 2:
The invention changes the state parameters of the protocol stack during path switching. By controlling the transition of protocol stack states (e.g., activating or deactivating specific layers), the system achieves flexible relaying while managing complexity through controlled parameter changes rather than complete protocol reconfiguration.
3Adaptability or versatility
If a single-hop relaying environment is used, then the network coverage requirement is simplified, but the ability to handle partial-coverage scenarios and mobility is limited
Solution Approach 1:
The system dynamically adapts the relaying configuration based on the operational requirements. In single-hop scenarios, the relay UE connects directly to the network, while in multi-hop scenarios, relay UEs can be configured to connect to other relay UEs. This dynamic configuration capability allows the system to handle both simplified and complex coverage scenarios flexibly.
Solution Approach 2:
The path switch mechanism is designed to be universal, working effectively in both single-hop and multi-hop relaying environments. The same basic mechanism of preparing and switching between relay UEs can handle various coverage scenarios, from full network coverage to partial coverage, making the system versatile without requiring separate solutions for each scenario.
Data Source
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AI summary
An indirect-to-indirect path switching procedure is proposed for transferring operation of a remote user equipment, UE, from a first relay UE to a second relay UE, while preserving continuity of the user's service(s) offered by a cellular network through the first and second relay UEs, in a layer 2 UE-to-network relaying architecture.