D2D Relay Path Switching for Cellular Coverage and Capacity
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Solution Overview
Problem
Traditional BS-centric cellular networks face limitations in supporting high data rate capabilities and proximity services, necessitating the development of device-to-device (D2D) communications to enhance system capacity, coverage, and reduce battery power consumption.
Innovation Solution
Implementing device-to-device (D2D) communications with multi-path relay configurations, allowing UEs to communicate indirectly through relay UEs and directly with the BS, and enabling path switching between single and multiple paths to optimize communication methods based on measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional BS-centric cellular networks are used, then network infrastructure is established, but system capacity and data rate capabilities are limited
Solution Approach 1:
The patent introduces relay UEs as intermediary nodes that enable D2D communication between remote UEs and the network. The relay UE acts as a mediator to forward traffic between the remote UE and the BS, allowing UEs in coverage holes to access network services without requiring direct BS connection. This resolves the contradiction by enabling additional users to share network resources through relay nodes rather than requiring direct infrastructure connection for each user.
Solution Approach 2:
The patent segments the communication path into multiple segments: direct path from remote UE to BS, and indirect path through relay UE. This segmentation allows flexible routing decisions and path switching between direct and relayed connections. The communication path is divided into separable segments that can be independently managed, enabling the system to adapt to different network conditions and optimize capacity utilization.
2Speed
If direct path communication is used, then data rate is improved, but network coverage is limited
Solution Approach 1:
The relay UE serves as an intermediary that extends network coverage to areas where direct BS connection is unavailable. By establishing an indirect path through the relay UE, remote UEs in coverage holes can access network services. The relay UE bridges the gap between the remote UE and the network, enabling coverage expansion without sacrificing data rate capability.
Solution Approach 2:
The patent implements dynamic path switching between direct and indirect communication paths based on real-time network conditions. The system can switch between paths to optimize both coverage and data rate performance. This dynamic adaptability allows the system to maintain high data rates when direct connection is available while providing coverage where needed through relay paths.
3Reliability
If single path communication is used, then path switching complexity is reduced, but communication reliability is insufficient
Solution Approach 1:
The patent applies different quality characteristics to different communication paths: the direct path provides high data rate capability when available, while the indirect path through relay UE provides coverage extension. Each path has locally optimized quality properties that are selected based on current network conditions. This allows the system to achieve high reliability through path diversity without requiring complex unified path management.
Solution Approach 2:
The system dynamically selects between direct and indirect paths based on real-time measurements of link quality, coverage availability, and network conditions. The path switching is triggered by changes in network state rather than requiring continuous complex management. This dynamic approach improves reliability through adaptive path selection while keeping the control mechanism relatively simple.
4Area of stationary object
If relay UE is introduced for indirect communication, then network coverage is extended, but communication overhead increases
Solution Approach 1:
The relay UE acts as an efficient intermediary that consolidates traffic routing decisions. By centralizing the relay function in a dedicated node, the system avoids the overhead of distributed path selection and management. The relay UE handles the complexity of indirect routing locally, reducing the information exchange requirements between remote UEs and the network core.
Data Source
AI summary
In some arrangements, a first BS (source BS) sends to a second BS (target BS) a handover request including a target cell ID. A remote UE is communicating with the first BS via a first indirect path including a first SL between the remote UE and a first relay UE or a first direct path between the remote UE and the first BS. The target cell ID includes an ID of a serving cell (e.g., serving cell ID or NCGI) of a second relay UE or a serving cell of the direct path. The first BS receives from the second BS a handover response.