Multi-DU Cell Mobility Using L1/L2 Activation Signaling
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Solution Overview
Problem
Existing wireless communication systems face challenges in efficiently managing layer 1 (L1) and layer 2 (L2) mobility in multiple distributed unit (DU) deployments, particularly in scenarios involving user equipment (UE) switching between cells managed by different DUs within a central unit (CU).
Innovation Solution
The solution involves determining to switch from a first cell of a first DU to a second cell of a second DU and communicating using layer 1 (L1) or layer 2 (L2) signaling to change the activation status of at least one cell, thereby facilitating seamless transitions between cells within a set of DUs under a CU.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional mobility management is used in multi-DU deployments, then switching between cells managed by different DUs is possible, but the process is complex and inefficient with increased signaling overhead
Solution Approach 1:
The patent segments the mobility management process by introducing separate mobility indication messages at different protocol layers (L1 mobility indication and L2 mobility indication). This segmentation allows the system to handle mobility events more efficiently by processing them at appropriate layers rather than requiring complex end-to-end signaling, thus improving switching efficiency while reducing overall system complexity.
Solution Approach 2:
The patent implements preliminary action by having the network pre-configure multiple candidate cells for a UE before mobility events occur. The gNB provides mobility indications in advance, allowing the UE to prepare for potential cell switches. This preliminary configuration reduces the complexity and time required for actual mobility switching, as the decision framework is already established.
2Speed
If layer 1 and layer 2 signaling are used for cell switching, then switching speed is improved, but signaling overhead increases
Solution Approach 1:
The patent applies partial action by implementing mobility management at only the necessary protocol layers (L1 and L2) rather than requiring full L3 RRC signaling for all mobility events. This partial approach enables faster switching for frequent cell changes while maintaining appropriate higher-layer control for significant mobility events, thus achieving speed improvement without excessive signaling overhead across all layers.
Solution Approach 2:
The patent changes the parameter of mobility indication timing and layer by introducing separate L1 and L2 mobility indication mechanisms with different timing characteristics. L1 provides immediate indications for rapid switching, while L2 provides slightly delayed but more comprehensive information. This parameter differentiation allows the system to optimize switching speed for time-critical events while managing overall signaling overhead through layered processing.
3Reliability
If multiple distributed units are deployed to improve coverage and capacity, then network performance is enhanced, but coordination and management between DUs becomes more difficult
Solution Approach 1:
The patent introduces the gNB as an intermediary that centralizes the coordination of multiple DUs. The gNB receives mobility indications and makes centralized decisions about cell switching across different DUs, then communicates these decisions back to the appropriate DUs and UEs. This intermediary approach maintains the coverage and capacity benefits of multi-DU deployment while simplifying coordination through a centralized decision-making point.
Solution Approach 2:
The patent implements universality by creating a standardized mobility indication and handling mechanism that works across all DUs under a gNB. The same L1 and L2 mobility indication procedures apply regardless of which specific DUs are involved, providing a universal framework for multi-DU coordination. This multi-functional approach allows the system to manage diverse DU configurations through a single coordinated process.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may determine to switch from a first cell of a first distributed unit (DU) to a second cell of a second DU, wherein the first DU and the second DU are included in a set of DUs of a central unit (CU). The UE may communicate, using layer 1 (L1) or layer 2 (L2) signaling to change an activation status of at least one cell of the first DU or the second DU. The UE may switch from the first cell to the second cell in connection with the change to the activation status of the at least one cell of the first DU or the second DU. Numerous other aspects are provided.