UE-Triggered Lower-Layer Handover Using Filtered CSI-RS Measurements
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Solution Overview
Problem
Existing wireless communication systems face challenges in reducing latency and signaling overhead during handovers in 5G New Radio networks, particularly in Layer 3-based handovers, which can result in large latency and inefficient resource utilization.
Innovation Solution
Implementing UE-triggered Layer 1/Layer 2-based handover procedures using conditions such as quality thresholds and metrics like RSRP, RSRQ, and SINR, with filtering techniques applied to CSI-RS measurements, and options for UE to send handover requests via MAC CE or PUCCH, allowing direct synchronization to target cells without gNB command.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If Layer 3-based handover procedures are used, then handover decisions can be made with comprehensive measurement information, but latency and signaling overhead increase significantly
Solution Approach 1:
The patent segments the handover measurement process into two distinct parts: Layer 1 filtering/averaging of raw measurements (CSI-RS, SSB) to generate preliminary RSRP/RSRQ values, and Layer 3 evaluation of these filtered values for handover decisions. This segmentation allows Layer 1 to handle time-critical filtering operations with lower latency while Layer 3 focuses on decision-making, thereby reducing overall handover latency while preserving measurement accuracy through the two-stage processing approach.
Solution Approach 2:
The patent implements preliminary filtering and averaging of measurement values at Layer 1 before they reach Layer 3 for handover decisions. By pre-processing the raw measurements (CSI-RS, SSB) to generate filtered RSRP and RSRQ values at Layer 1, the system prepares measurement data in advance, reducing the processing burden and latency at Layer 3 while maintaining comprehensive measurement information for accurate handover decisions.
2Measurement precision
If Layer 3-based handover procedures are used, then comprehensive measurement evaluation can be performed, but signaling overhead increases
Solution Approach 1:
The patent extracts the filtering and averaging operations from Layer 3 and relocates them to Layer 1. By taking out these time-consuming processing tasks from Layer 3 and performing them at Layer 1, the patent reduces the signaling overhead and processing burden at Layer 3 while maintaining the comprehensive measurement evaluation capability. Layer 3 receives pre-processed, filtered measurement values rather than raw measurements, reducing the information processing requirements.
3Loss of time
If UE-triggered handover with Layer 1/Layer 2 signaling is implemented, then handover latency is reduced, but handover control complexity increases
Solution Approach 1:
The patent implements self-service handover by enabling the UE to autonomously trigger handover decisions based on Layer 1 filtered measurements and Layer 3 evaluation, without requiring continuous gNB commands. The UE independently evaluates filtered RSRP and RSRQ values against thresholds and triggers handover when conditions are met, reducing handover latency by eliminating waiting for gNB commands while managing control complexity through standardized threshold-based decision logic.
Data Source
AI summary
Performing a UE-triggered lower layer-based handover may include performing measurements of source gNB CSI-RS samples associated with a source gNB. Measurements of target gNB CSI-RS samples associated with a target gNB may be performed, wherein the CSI-RS samples associated with the source gNB and the CSI-RS samples associated with the target gNB are transmitted in a burst structure. A subset of the source gNB CSI-RS samples and the target gNB CSI-RS samples may be filtered using a layer 1 or a layer 2 filter. A filtered result for each of the subset of source gNB CSI-RS samples and the subset of target gNB CSI-RS samples may be generated. Based on the generated filtered result for each of the subset of source gNB CSI-RS samples and the subset of target gNB CSI-RS samples, determining whether a handover from the source gNB to the target gNB is to occur.