L3 Handover Commands With L1/L2 Cell Mobility for Fast Cell Switching
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Solution Overview
Problem
Existing wireless communication systems face increased latency and decreased reliability during cell handovers due to the use of higher-layer signaling like L3 handovers, which can lead to suboptimal cell changes, especially in scenarios with rapid signal changes or frequent handovers.
Innovation Solution
Incorporating L1/L2 cell mobility information within an L3 handover command to enable immediate cell switching post-handover, including indications of new cell sets, activated subsets, and beam information, allowing for quicker adaptation to communication issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If L3 handover commands are used for cell mobility, then handover control is centralized and manageable, but latency increases and reliability decreases during rapid signal changes
Solution Approach 1:
The patent segments the handover process into two independent parts: L3 handover for network-level cell selection and L1/L2 handover for rapid signal-based cell switching. This segmentation allows each layer to operate independently, with L1/L2 providing low-latency response for signal changes while L3 maintains centralized control for broader network coordination, thereby resolving the contradiction between reliability and latency.
Solution Approach 2:
The patent implements preliminary configuration where the network pre-configures L1/L2 handover parameters and cell lists before actual handover occurs. This preliminary setup enables the UE to execute rapid L1/L2 handovers without waiting for real-time L3 commands, reducing latency while maintaining reliability through pre-validated configuration.
2Speed
If only L3 handover is used, then network control is simplified, but the system cannot respond quickly to rapid signal changes
Solution Approach 1:
The patent divides handover control into L3 for network-level decisions and L1/L2 for rapid signal-based responses. This segmentation enables fast L1/L2 handovers for signal changes while keeping L3 control simplified for network coordination, resolving the contradiction between speed and complexity.
Solution Approach 2:
The patent introduces L1/L2 handover as an intermediary mechanism between the UE and the network for rapid cell switching. This intermediary layer handles time-critical signal changes independently from L3, allowing fast response without increasing overall system complexity, as L1/L2 operates as a standardized interface.
3Reliability
If L1/L2 cell mobility is added to L3 handover, then response time to signal changes improves, but signaling complexity increases
Solution Approach 1:
The patent makes the L1/L2 handover mechanism universal by configuring it to work with existing L3 handover procedures rather than creating a separate parallel system. The same cell list and measurement configurations used in L3 handover are also utilized for L1/L2 handover, providing multi-functionality that reduces signaling complexity while improving reliability through dual-layer support.
Solution Approach 2:
The patent merges L1/L2 handover signaling with existing L3 handover signaling structures. By combining the configuration of cell lists, measurement parameters, and handover triggers into unified signaling messages, the patent reduces overall signaling complexity while enabling both L3 and L1/L2 handover functions to operate together for enhanced reliability.
Data Source
AI summary
Methods, systems, and devices for wireless communications are described to support inclusion of layer 1 (L1) or layer 2 (L2) cell mobility information within a layer 3 (L3) handover command. A base station may transmit, to the UE, signaling indicating for the UE to perform a measurement on a first set of cells. The UE may perform the measurement on the first set of cells and may transmit, to the base station, an indication associated with the measurement on the first set of cells. In response to the indication, the base station may transmit, to the UE, an L3 handover command, where the L3 handover command may include L1 or L2 cell mobility information, such as an indication of a second set of cells that the UE is to use for L1 or L2 cell mobility after completing the L3 handover command.