Inter-system Handover Optimization in Wireless Networks
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Solution Overview
Problem
Current wireless communication systems face challenges in reducing latency and handover failures during inter-system handovers between different radio access technologies, particularly due to complex processes and inefficient data traffic management.
Innovation Solution
A method where a source node transmits a neighbor list with parameters and criteria to user equipment (UE) to facilitate handovers to target nodes, allowing UE to determine when to initiate handovers based on reception quality and data traffic loading, thereby reducing latency and connection errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional inter-system handover procedures are used, then handover between different radio access technologies is achieved, but latency increases and handover failures occur
Solution Approach 1:
The source node provides the UE with a neighbor list containing target node information and handover criteria in advance, allowing the UE to prepare for handover by monitoring signal conditions without immediate action. When criteria are met, the UE can quickly execute handover to target nodes from different RATs, reducing latency while maintaining reliability through pre-configured handover parameters.
2Adaptability or versatility
If complex handover procedures are used to accommodate multiple radio access technologies, then inter-system handover capability is improved, but device complexity increases
Solution Approach 1:
The handover process is segmented into distinct phases: the source node provides neighbor list information, the UE independently evaluates criteria and selects target nodes, and the UE executes handover autonomously. This segmentation simplifies the overall process by dividing responsibilities between network and device, reducing complexity while maintaining broad RAT compatibility.
Solution Approach 2:
The UE autonomously monitors signal conditions, evaluates handover criteria, selects target nodes from different RATs, and executes handover decisions without extensive network control. This self-service approach reduces device complexity by eliminating the need for complex network-coordinated procedures while maintaining high adaptability across multiple radio access technologies.
3Measurement precision
If frequent handover monitoring is performed, then handover timing accuracy is improved, but energy consumption increases
Solution Approach 1:
The UE periodically monitors signal conditions from source and target nodes according to pre-configured criteria rather than continuously scanning. This periodic monitoring maintains sufficient timing accuracy for optimal handover decisions while significantly reducing energy consumption compared to continuous monitoring, as the UE can enter low-power states between measurement intervals.
Data Source
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AI summary
An inter-system handover system for a wireless communication system supports hand-down and hand-up of user equipment (UE) to different radio access technologies, including synchronous and asynchronous systems. Latency and handover connection failures are reduced by an access node (nodeB) broadcasting information about neighboring systems (targets) when the UE reception (RX) capability is both inside or outside the reception range of the target. A single RX chain is sufficient, although transitioning between a wireless wide area network (WWAN) to a wireless local area network may (WLAN) may advantageously benefit from simultaneous operation on two Rx chains. Optimized list of neighboring RAT systems (targets) are broadcast from the network, including measurement parameters and reporting instructions. Thereby, UE-driven reporting minimizes latencies. UE reports other-system searches to network only if needed for a handover. In addition, handover requests can be bundled with other-system measurement information, if necessary, for additional efficiencies.