Conditional Handover Using Ordered Target Cells in 5G NR
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Solution Overview
Problem
The conventional handover procedures in 5G NR networks, particularly in non-terrestrial networks like satellite communications, face challenges such as frequent mobility events, high signaling delays, and unreliable RSRP measurements, leading to increased resource reservation and service interruptions.
Innovation Solution
A solution involving an ordered list of target cells is configured for terminal devices based on location-related data, allowing for a chain of handovers to be prepared in advance, reducing the need for repeated resource reservation and minimizing service interruptions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional handover procedures are used in 5G NR networks, then handover can be performed between cells, but frequent mobility events lead to increased resource reservation and service interruptions
Solution Approach 1:
The patent applies preliminary action by configuring an ordered list of target cells in advance based on location-related data before handover is needed. The terminal device can directly execute handover to the next target cell in the ordered list when mobility events occur, eliminating the need for real-time measurement reporting and handover decision-making. This pre-prepared handover path significantly reduces service interruption time while maintaining reliable service continuity.
2Reliability
If conventional handover procedures are used in satellite communications, then handover can be performed between satellite beams, but high signaling delays worsen handover performance
Solution Approach 1:
The patent resolves the signaling delay issue in satellite communications by pre-configuring the ordered list of target cells based on terminal location and satellite beam coverage information. Since the handover target is predetermined, the terminal device does not need to engage in real-time signaling exchanges with the network for handover decision-making, thereby eliminating the impact of high signaling delays on handover performance while maintaining reliability.
3Reliability
If conventional handover procedures are used in non-terrestrial networks, then handover can be performed between cells, but unreliable RSRP measurements lead to incorrect handover decisions
Solution Approach 1:
The patent addresses the unreliable RSRP measurements in non-terrestrial networks by using pre-configured ordered lists of target cells based on terminal location data and satellite beam coverage information. This approach replaces real-time RSRP-based handover decisions with predetermined handover targets, eliminating the impact of measurement inaccuracies on handover decision accuracy while maintaining reliable service continuity.
4Reliability
If multiple target cells are prepared for conditional handover, then handover robustness is enhanced, but resource reservation increases
Solution Approach 1:
The patent optimizes resource reservation by configuring a single ordered list of target cells in advance rather than preparing multiple independent conditional handover configurations. The terminal device executes handover to the next available target cell in the ordered list, which reduces the number of resources that need to be reserved across multiple target cells while maintaining handover robustness through the pre-prepared handover path.
Data Source
AI summary
Embodiments of the present disclosure relate to conditional handover. A method comprises: determining, at a first device, an ordered list of target cells for a second device to initiate handover to in order based at least in part on location-related data of the second device, the second device being served in a source cell of the first device; transmitting, to the second device, first information indicating the ordered list of target cells and radio configurations associated with each of the target cells; and causing second information indicating the ordered list of target cells to be transmitted to at least one third device serving target cells in the ordered list, to request allocation of resources for the handover by the at least one third device. In this way, a chain of target cells regarding future handover is determined in a predetermined order, which avoid multiple cells prepare for a same handover, thus reducing handover preparation latency and improving the service continuity.