Conditional Handover Execution in 5G Wireless Systems
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Solution Overview
Problem
Current wireless communication systems, particularly in LTE and NR, face challenges in efficiently managing handovers, leading to increased interruption times and reduced reliability due to factors like weak signal conditions and heavy load on serving base stations.
Innovation Solution
A method is introduced where the user equipment (UE) evaluates execution conditions for candidate target cells and initiates handovers based on predetermined criteria, including measurement reports, to minimize interruption time and enhance mobility by autonomously executing conditional handovers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the UE waits for network confirmation before handover, then handover reliability is improved, but handover interruption time increases
Solution Approach 1:
The network pre-configures the UE with multiple candidate target cells and their corresponding execution conditions before the handover is actually needed. The UE evaluates these pre-prepared conditions and autonomously executes handover when conditions are met, eliminating the need to wait for network confirmation during actual handover execution. This preliminary preparation resolves the contradiction by enabling fast autonomous execution while maintaining reliability through pre-validated candidate cells.
Solution Approach 2:
The UE is empowered to autonomously evaluate execution conditions and select target cells based on pre-configured criteria without continuous network intervention. The UE monitors signal conditions, evaluates candidate cells independently, and executes handover decisions locally. This self-service capability reduces handover interruption time while maintaining reliability through the structured preconfiguration provided by the network.
2Reliability
If the network manages all handover decisions centrally, then handover reliability is improved, but device complexity and signaling overhead increase
Solution Approach 1:
The handover management function is segmented into two parts: the network provides preconfiguration and candidate cell information, while the UE performs autonomous evaluation and execution. This segmentation distributes complexity appropriately - the network handles high-level policy and candidate selection, while the UE handles real-time condition evaluation and execution. This resolves the contradiction by reducing signaling overhead and device complexity while maintaining reliability through the collaborative architecture.
Solution Approach 2:
The network performs preliminary handover preparation by identifying and pre-configuring candidate target cells with their execution conditions before the UE needs to execute handover. This preliminary action transfers the burden of complex decision-making to the network in advance, allowing the UE to perform simpler real-time condition evaluation. This resolves the contradiction by reducing ongoing signaling overhead and UE complexity while maintaining centralized control for reliability.
3Reliability
If multiple candidate target cells are pre-configured, then handover reliability is improved, but signaling overhead and network load increase
Solution Approach 1:
The network provides different levels of handover configuration to different UEs or different scenarios based on local conditions. Not all UEs receive the same number of candidate cells - the network tailors the preconfiguration to individual UE needs, mobility patterns, and service requirements. This local quality approach reduces overall signaling overhead while maintaining reliability for each UE by providing appropriate candidate cell configurations.
Solution Approach 2:
The network configures a limited number of candidate target cells (e.g., top 1-3 candidates) rather than all possible target cells. This partial action provides sufficient handover options to maintain reliability while avoiding the excessive signaling overhead of configuring every possible target cell. The UE evaluates only the pre-configured candidates, reducing both network load and UE processing requirements while maintaining handover reliability.
Data Source
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AI summary
The disclosure relates to a communication method and a system for converging a 5th-Generation (5G) communication system for supporting higher data rates beyond a 4th-Generation (4G) system with a technology for Internet of Things (IoT). The disclosure may be applied to intelligent services based on the 5G communication technology and the IoT-related technology, such as smart home, smart building, smart city, smart car, connected car, health care, digital education, smart retail, security and safety services. A method for executing a handover by a UE in a wireless communication system is provided. The method includes receiving, by a user equipments (UE), from a source cell a handover configuration comprising an execution condition associated with at least one candidate target cell from a plurality of candidate target cells and a configuration associated with the at least one candidate target cell from a plurality of candidate target cells.