Inter-RAT Mobility Prioritization for Low-Latency 5G-6G Handover
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Solution Overview
Problem
Existing 3GPP Layer 1/Layer 2 Triggered Mobility (LTM) procedures in 5G networks lead to inefficiencies due to UEs following random access procedures even when they can derive Timing Advance (TA) values themselves, and 6G mobility solutions like Multi-Radio Access Technology Spectrum Sharing (MRSS) are not yet developed for instantaneous high data rates.
Innovation Solution
Implementing inter-Radio Access Technology (RAT) mobility prioritization methods, where a wireless transmit and/or receive unit (WTRU) measures conditions and priorities between 5G and 6G networks, adjusting measurement frequencies and procedures based on network quality and thresholds to optimize handovers and reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If UE follows random access procedures for cell switching, then handover reliability is improved, but mobility latency increases and procedure efficiency deteriorates
Solution Approach 1:
The network pre-configures multiple candidate cells with their respective TA values before handover is needed. When handover is triggered, the UE can immediately use the pre-obtained TA value to switch cells without performing random access procedures, thus reducing mobility latency while maintaining reliability through pre-validation of candidate cells by the network
2Measurement precision
If UE performs frequent RRM measurements on all candidate cells, then handover decision accuracy is improved, but device complexity and power consumption increase
Solution Approach 1:
The UE applies different measurement strategies to different candidate cells based on their priority and characteristics. High-priority candidates receive frequent measurements while lower-priority ones are measured less often. The network provides prioritization information to guide the UE's measurement efforts, reducing overall complexity while maintaining accurate handover decisions
3Measurement precision
If UE performs full random access procedures for cell switching, then timing synchronization accuracy is improved, but procedure overhead and latency increase
Solution Approach 1:
The UE autonomously derives or uses pre-configured TA values to perform timing advance for cell switching without requiring the network to coordinate full random access procedures. This self-service approach allows the UE to maintain timing synchronization independently, significantly improving handover efficiency while the network retains oversight through pre-configuration and validation
Data Source
AI summary
Methods and systems are provided for inter-Radio Access Technology (RAT) mobility prioritization between two wireless networks, each having a RAT, such as 5G and 6G. The methods involve requesting information about each RAT and their respective networks, receiving an indication of a priority of one RAT relative to the other, and performing mobility procedures based on the priority. These procedures include measurement configurations, identifying candidate cells, and activating or deactivating mobility procedures. The system includes a wireless transmit and/or receive unit (WTRU) configured to request information, determine priorities, and perform mobility procedures. Mobility procedures are controlled between different wireless networks based on their conditions and priorities, thereby making efficient use of network resources and enabling seamless transitions between network technologies.