User Terminal Frame Timing Determination for Low Latency Mobility
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Solution Overview
Problem
Future radio communication systems face significant latency issues during mobility control procedures such as handover and cell re-selection, as well as cell addition procedures, particularly due to the need to decode PBCH signals to determine frame timing and SFN alignment between cells.
Innovation Solution
A user terminal is equipped with a receiving section to detect measurement signals from multiple cells and a control section that determines whether the radio frame timings and SFN numbers match between cells, allowing for synchronized operations without always decoding the PBCH, thereby reducing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PBCH decoding is performed to determine frame timing and SFN alignment between cells, then measurement precision is improved, but latency time increases
Solution Approach 1:
The system performs preliminary actions by using alternative methods (such as using SSB timing or pre-configured synchronization information) to determine frame timing and SFN alignment before PBCH decoding is required. This allows the user terminal to proceed with mobility control procedures without waiting for complete PBCH decoding, thereby reducing latency while still achieving accurate timing alignment when needed.
Solution Approach 2:
The invention extracts the essential timing information (frame timing and SFN alignment) from the PBCH decoding process and makes it available through alternative, faster means. By separating the timing determination function from the complete PBCH decoding process, the system can obtain timing information without the full overhead of PBCH decoding, thus reducing latency in mobility procedures.
2Reliability
If complete PBCH decoding is performed for every cell measurement, then reliability of timing information is improved, but processing time and complexity increase
Solution Approach 1:
The system applies partial action by performing only the necessary portion of PBCH decoding or using alternative methods to obtain timing information without completing full PBCH decoding in all cases. This partial approach provides sufficient reliability for timing determination while significantly reducing processing complexity and enabling faster execution of mobility control procedures.
Solution Approach 2:
The invention uses timing information from synchronization signals (such as SSB) as a copy or substitute for the timing information that would be obtained through complete PBCH decoding. This copied timing information is sufficient for determining frame timing and SFN alignment, reducing processing complexity while maintaining the reliability needed for mobility control procedures.
Data Source
AI summary
A user terminal according to one aspect of the present disclosure includes: a receiving section that receives measurement signals of a first cell and a second cell; and a control section that, when at least one of handover, cell re-selection and a cell addition procedure is performed based on a measurement result that uses the measurement signals, determines whether or not to assume that timings of radio frames and numbers assigned to the radio frames match between the first cell and the second cell.