L2 Relay Node Uplink Synchronization via Contention-Free Random Access
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Solution Overview
Problem
In Layer 2 relay communication architecture, control information of the PHY layer, MAC sublayer, or RLC sublayer cannot be forwarded to a base station through a relay node, and uplink synchronization is not maintained, preventing effective transmission of uplink information via the Uu interface.
Innovation Solution
The method involves a node acquiring specific random access resources and utilizing a contention-free random access procedure to achieve uplink synchronization, enabling the transmission of end-to-end control information via the Uu interface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a Layer 2 relay communication architecture is used to forward data through a relay node, then data forwarding capability is improved, but control information of the PHY layer, MAC sublayer, or RLC sublayer cannot be transmitted to the base station
Solution Approach 1:
The protocol stack is segmented into two parts: L2 relay functions for data forwarding, and L3 relay functions for control information transmission. This allows different types of information to use different transmission paths - data goes through the relay node via L2, while control information uses the Uu interface via L3
Solution Approach 2:
The base station acts as an intermediary that receives control information directly from the remote node through the Uu interface, bypassing the relay node for control plane communication while still using the relay node for user plane data forwarding
2Device complexity
If uplink synchronization is not maintained with the base station, then hardware complexity is reduced, but effective transmission of uplink information via the Uu interface is prevented
Solution Approach 1:
The system implements partial synchronization - the remote node maintains uplink synchronization with the base station only when needed for control information transmission, rather than continuously maintaining synchronization for all operations
Solution Approach 2:
The synchronization state is made dynamic rather than static. The remote node can switch between synchronized and unsynchronized states based on whether control information needs to be transmitted, allowing the system to adapt its complexity level to actual needs
3Device complexity
If a unified solution is adopted for various scenarios including V2X and terminal-base station communications, then hardware complexity and costs are reduced, but scenario-specific optimization may be limited
Solution Approach 1:
The relay communication architecture is designed with universal components that can function across multiple scenarios. The same L2/L3 relay mechanism, Uu interface configuration, and random access procedures work for both V2X communications and traditional terminal-base station communications, eliminating the need for separate hardware implementations
Data Source
AI summary
The present disclosure provides a method and device used for relay wireless communications. A first node transmits a first radio signal, the first radio signal comprises a first message; transmits a third radio signal on a first radio resource; and receives a second radio signal, the second radio signal comprises a second message, the second message is used to indicate the first radio resource; wherein the first message is used to trigger the second message, and the first radio resource is used for a non-competitive random access. In the L2 relay communication architecture of the present disclosure, the first node acquires a UL synchronization through a non-competitive random access procedure, which can effectively support transmitting end-to-end control information of the PHY layer or the higher layer via a Uu interface.