Cell Set Based Mobility for 5G NR Handover
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Solution Overview
Problem
Current wireless communication systems face challenges in providing seamless mobility, especially in dense small cell deployments, due to increased signaling overhead, frequent data transmission interruptions, and reduced handover reliability in 5G New Radio (NR) high-frequency environments.
Innovation Solution
Implementing cell set-based mobility techniques that allow for intra-frequency and inter-frequency mobility within and between cell sets, enabling reduced interruption time, lower handover overhead, and improved reliability by sharing UE context and configuration information between cells within a set, thereby minimizing the need for core network involvement and optimizing radio resource management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional handover procedures are used in dense small cell deployments, then mobility between cells can be supported, but signaling overhead increases and handover reliability decreases
Solution Approach 1:
The patent segments the cell group into a serving cell and neighbor cells within the same cell set. When mobility occurs within a cell set, only the serving cell changes while the cell set remains the same, eliminating the need for full handover signaling. This segmentation allows the system to distinguish between intra-cell-set mobility (requiring minimal signaling) and inter-cell-set mobility (requiring full handover procedures), thereby reducing overall signaling overhead while maintaining reliability.
Solution Approach 2:
The patent performs preliminary configuration of neighbor cells within the cell set before mobility events occur. The network pre-configures measurement parameters, cell set identities, and neighbor cell information for all cells within a cell set. This preliminary action ensures that when mobility is needed, the UE and network already have the necessary information ready, eliminating the need for extensive signaling during the actual handover process and improving handover reliability.
2Productivity
If frequent handovers are performed in dense small cell deployments, then mobility between cells is enabled, but data transmission interruptions increase
Solution Approach 1:
The patent segments mobility into two types: intra-cell-set mobility and inter-cell-set mobility. For intra-cell-set mobility, only the serving cell changes while maintaining the same cell set, which eliminates the need for PDCCH configuration changes and reduces interruption time. For inter-cell-set mobility, full handover procedures are performed. This segmentation enables frequent mobility within cell sets without the time-consuming interruptions of traditional handovers, thereby improving productivity while minimizing time loss.
Solution Approach 2:
The patent maintains continuity of useful action by keeping the cell set identity and associated PDCCH configurations active throughout intra-cell-set mobility events. Since the cell set remains the same, the UE can maintain its connection to the cell set and continue data transmission without interruption, even as the serving cell changes. This continuity eliminates the breaks in data transmission that occur during traditional handovers, enabling seamless mobility.
3Loss of time
If cell set-based mobility is implemented, then interruption time and overhead are reduced, but complexity of mobility management increases
Solution Approach 1:
The patent merges the management of multiple neighbor cells into a single cell set entity. Instead of managing each neighbor cell independently, the network groups multiple cells into a cell set with a single identity and shared PDCCH configurations. This merging simplifies mobility management by reducing the number of independent entities that need to be tracked and configured, thereby reducing complexity while enabling reduced interruption time for intra-cell-set mobility.
Solution Approach 2:
The cell set structure provides universality by serving multiple functions simultaneously: it acts as a mobility container, a configuration group, and a signaling reduction mechanism. The same cell set structure enables both intra-cell-set mobility (with reduced overhead) and inter-cell-set mobility (with full handover support). This multi-functionality reduces the need for separate management mechanisms, thereby reducing overall complexity while achieving the goal of reduced interruption time.
Data Source
AI summary
This disclosure relates to techniques for supporting cell set based mobility. A network may provide configuration information to a wireless device, relating to a current cell and possibly to one or more other cells in one or more cell sets. The wireless device and network may take various measurements. In response to the measurements and the configuration information, the wireless device may perform a cell change to one of the other cells.