L2 U2N Relay Egress Link Mapping via RRC and PC5 IDs
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently determining and managing egress links for Layer-2 UE-to-Network Relay (L2 U2N) operations, particularly in scenarios involving multiple intermediate U2N Relay UEs, which can lead to inefficiencies and interference in data transmission.
Innovation Solution
A method and apparatus for L2 U2N Relay UE to establish a PC5 connection with an Intermediate U2N Relay UE, receive a RRC Reconfiguration message with local IDs, and determine an egress link based on matching UE IDs, ensuring proper bearer mapping and data transmission through Uu and PC5 interfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If L2 U2N Relay UE uses existing egress link determination methods, then network connectivity is maintained, but data transmission efficiency deteriorates and interference increases in multi-hop relay scenarios
Solution Approach 1:
The patent introduces an intermediary mechanism using RRC reconfiguration messages as carriers to transport L2 ID mapping information between the network node and Relay UE. This intermediary data structure enables precise identification of egress links without direct interference between multiple relay paths, resolving the efficiency-interference contradiction in multi-hop scenarios
Solution Approach 2:
The patent replaces traditional mechanical/link-layer egress determination methods with a network-controlled RRC signaling-based identification system. By substituting the determination mechanism from implicit layer-2 arbitration to explicit network-configured ID mapping, the system achieves higher transmission efficiency while maintaining reliability through network coordination
2Adaptability or versatility
If L2 U2N Relay UE establishes multiple PC5 connections with intermediate relay UEs, then network coverage is extended, but egress link determination complexity increases
Solution Approach 1:
The patent segments the egress link determination problem by introducing separate L2 ID identifiers for each intermediate relay UE connection. Each PC5 connection gets a dedicated L2 ID that is independently managed and mapped through RRC reconfiguration messages, allowing the Relay UE to distinguish between multiple hops without complexity escalation
Solution Approach 2:
The patent applies preliminary action by having the network node pre-configure and inject L2 ID mapping information into RRC reconfiguration messages before data transmission occurs. This advance setup eliminates the need for real-time complex arbitration, simplifying egress link determination while supporting extended network coverage through multiple relay connections
Data Source
AI summary
A method and device for a Layer-2 (L2) UE-to-Network (U2N) Relay User Equipment (UE) are disclosed. In one embodiment, the L2 U2N Relay UE establishes a PC5 connection with an Intermediate U2N Relay UE and establishes a Radio Resource Control (RRC) connection with a network node. The L2 U2N Relay UE also receives a RRC Reconfiguration message from the network node, wherein the RRC Reconfiguration message includes a local identity (ID) of a Remote UE and also includes a L2 ID of the Intermediate U2N Relay UE to associate with the local ID of the Remote UE. Furthermore, the L2 U2N Relay UE receives a Uu Sidelink Relay Adaptation Protocol (SRAP) Protocol Data Unit (PDU) from the network node, wherein the Uu SRAP PDU includes a first header and a data packet and wherein the first header includes a UE ID.