RACH Occasion Selection for NR FBE Random Access Timing
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Solution Overview
Problem
In a New Radio (NR) system operating at an unlicensed band with a Frame Based Equipment (FBE) channel access mode, the failure to transmit random access signals due to lack of downlink signal configuration or insufficient time for processing within the fixed frame period adversely affects access performance.
Innovation Solution
A method and terminal that determine a target time range based on the time domain position of a downlink signal within a fixed frame period, identifying invalid Random Access Channel (RACH) occasions by intersecting with this range, and avoiding mapping these occasions with synchronization signals and PBCH blocks to ensure valid RACH occasions are used for random access signal transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the terminal transmits random access signal in FBE channel access mode, then the system can operate in unlicensed band with fixed frame period structure, but the random access signal transmission may fail due to lack of downlink signal configuration or insufficient processing time
Solution Approach 1:
The terminal determines the target time range and identifies invalid RACH occasions in advance before attempting random access signal transmission. By performing this preliminary analysis of downlink signal timing and RACH occasion validity, the terminal avoids transmitting random access signals during time periods when downlink processing cannot be completed, thereby preventing transmission failures and improving access performance
Solution Approach 2:
The fixed frame period is segmented into valid and invalid RACH occasions based on downlink signal timing requirements. By dividing the RACH occasions into distinct valid and invalid segments, the terminal can selectively transmit random access signals only in valid occasions, ensuring sufficient downlink processing time while maintaining systematic operation in the unlicensed band
2Productivity
If the terminal uses all RACH occasions within fixed frame period, then the access opportunities are maximized, but some RACH occasions may be used when downlink signal processing time is insufficient
Solution Approach 1:
The terminal performs preliminary determination of invalid RACH occasions by analyzing the target time range based on downlink signal timing before the random access transmission process. This advance identification ensures that RACH occasions with insufficient downlink processing time are excluded from use, maintaining processing completeness while preserving all valid access opportunities
Solution Approach 2:
The terminal dynamically adjusts the set of usable RACH occasions based on the determined target time range and validity assessment. Rather than using a fixed set of RACH occasions, the terminal adapts the valid RACH occasion selection to the actual downlink signal timing conditions, optimizing both access opportunities and processing reliability
Data Source
AI summary
A random access signal transmission method, a terminal, and a non-transitory computer-readable storage medium are provided. The random access signal transmission method includes: determining a target time range according to a time domain position of a target downlink signal within a fixed frame period; and determining a Random Access Channel (RACH) occasion intersected with the target time range within the fixed frame period as an invalid RACH occasion according to configuration information of the fixed frame period and configuration information of the RACH occasion.