RACH-less Cell Handover Beam Configuration for 5G NR
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Solution Overview
Problem
In 5G NR communication systems, terminal devices face challenges in determining the correct beam for sending an RRC reconfiguration completion message during a RACH-less handover process, especially under multi-beam conditions, leading to delays and performance issues.
Innovation Solution
The method involves the target access network device acquiring beam measurement information from the terminal device, configuring appropriate beams and uplink resources, and sending a handover command that includes beam identifiers and time-domain information, allowing the terminal device to accurately determine the beam for RRC reconfiguration completion and PDCCH monitoring, thereby reducing handover delays and enhancing service performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a terminal device performs RACH-less handover in 5G NR under multi-beam conditions, then handover speed is improved, but the terminal device cannot determine the correct beam for sending RRC reconfiguration completion message, leading to handover failure
Solution Approach 1:
The target access network device pre-configures beam information and uplink resources before the handover is executed. The source access network device forwards this pre-configured information to the terminal device in the handover command, enabling the terminal to immediately use the correct beam without performing random access procedures.
Solution Approach 2:
The source access network device acts as an intermediary to forward the pre-configured beam information and uplink resources from the target access network device to the terminal device. This intermediary role ensures that the terminal receives accurate beam configuration without needing to perform beam selection itself.
2Measurement precision
If beam measurement information is acquired and pre-configured by the target access network device, then the terminal device can determine the correct beam accurately, but the handover procedure complexity increases
Solution Approach 1:
The beam measurement information, beam configuration, and uplink resource allocation are extracted from the complex handover procedure and pre-configured in advance by the target access network device. This extraction simplifies the terminal device's task to merely forwarding the pre-determined configuration without performing complex beam selection algorithms.
3Adaptability or versatility
If the terminal device performs random access procedure during handover, then beam selection can be done dynamically, but handover delay increases
Solution Approach 1:
The target access network device performs preliminary beam measurement and configuration before handover execution. This preliminary action eliminates the need for dynamic random access procedures during handover, reducing handover delay while maintaining beam selection adaptability through pre-computed optimal beam choices.
Data Source
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AI summary
The embodiments of the present application provide a cell handover method, an access network device and a terminal device. During cell handover in a RACH-less procedure, the terminal device can acquire a beam for sending an RRC reconfiguration completion message and monitoring a PDCCH, and an uplink resource on the beam, so that the time delay in the cell handover process can be reduced, and further, the service performance of 5G NR communication is satisfied. The method comprises: a target access network device acquiring a measurement report of the terminal device for the target cell, the measurement report comprising beam measurement information; the target access network device configuring, according to the beam measurement information, at least one beam by which the terminal device accesses the target cell, and configuring an uplink unlicensed resource on each beam of the at least one beam.