Adaptive Msg3 Repetition for Reliable NR Random Access
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Solution Overview
Problem
The robustness of Msg3 transmission in the NR Rel15/16 random access procedure is lower than other physical channels, leading to higher likelihood of random access failure, especially at the cell edge, resulting in increased random access time, and increasing the random access time.
Innovation Solution
A method and apparatus for Msg3 repetition based on threshold values and configuration parameters, including system information blocks, RAR information, and DCI scrambled by TC-RNTI or RA-RNTI, to determine and perform Msg3 repetition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Msg3 transmission is performed only once per scheduling in NR Rel15/16, then the random access procedure is simple, but the robustness of Msg3 transmission is low leading to higher random access failure likelihood
Solution Approach 1:
The Msg3 transmission is divided into multiple repetitions instead of a single transmission. The transport block is segmented and transmitted multiple times with different redundancy versions, improving reliability through diversity while maintaining manageable complexity through systematic segmentation
Solution Approach 2:
The network pre-configures a set of numbers of Msg3 repetitions and threshold values (T0, T1) before the random access procedure. This preliminary configuration allows the terminal to adaptively determine repetition numbers based on channel conditions without real-time negotiation, improving reliability while avoiding complex dynamic signaling
2Reliability
If Msg3 repetition is performed to improve reliability, then the robustness of Msg3 transmission increases, but the random access time increases
Solution Approach 1:
The number of Msg3 repetitions is dynamically adjusted based on channel conditions (signal strength, path loss) and terminal capability. The terminal compares measured channel parameters against pre-configured thresholds (T0, T1) to select appropriate repetition numbers from a pre-configured set, achieving adaptive reliability improvement without excessive time loss in good conditions
Solution Approach 2:
The system changes key parameters including the number of repetitions, redundancy versions, and time-frequency resources based on channel conditions and terminal capability. By varying these parameters adaptively, the system improves reliability when needed while minimizing time loss when channel conditions are good
3Reliability
If adaptive Msg3 repetition is implemented based on threshold values, then the reliability of Msg3 transmission improves, but the device complexity increases
Solution Approach 1:
The network pre-configures threshold values (T0 for signal strength, T1 for path loss) and a set of candidate repetition numbers before the random access procedure. The terminal only needs to perform simple comparisons between measured channel parameters and these pre-set thresholds, avoiding complex real-time decision algorithms while achieving adaptive reliability improvement
Solution Approach 2:
The terminal autonomously determines the number of Msg3 repetitions by comparing its measured channel conditions against the pre-configured thresholds and selecting from the pre-configured set of repetition numbers. This self-service mechanism improves reliability without requiring complex network-terminal coordination or additional signaling overhead
Data Source
AI summary
Embodiments of this application provide a message Msg3 transmission method, a terminal device, and a storage medium. The method includes: receiving, by a terminal device, a system information block (SIB); where the SIB includes: a first threshold value T0 of signal strength/signal quality/path loss; a second threshold value T1; and a set of numbers of Msg3 repetitions; receiving, by the terminal device, random access response (RAR) information or downlink control information (DCI) scrambled by a temporary cell radio network temporary identifier (TC-RNTI), where the RAR or the DCI scrambled by the TC-RNTI includes number of Msg3 repetitions; and performing Msg3 repetition according to the first threshold value T0, the second threshold value T1, the set of numbers of Msg3 repetitions and the number of Msg3 repetitions.