NR RACH Message Selection for Low-Latency Stable Access
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Solution Overview
Problem
The two-step RACH procedure in NR reduces latency but may compromise stability due to factors like message contention and channel conditions.
Innovation Solution
A mechanism that allows a terminal device to selectively choose between a first uplink message of a two-step RACH procedure and a second uplink message of a four-step RACH procedure, with a base station device setting a selection reference for this choice.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a two-step RACH procedure is used, then latency is reduced, but stability is compromised due to message contention and channel conditions
Solution Approach 1:
The patent implements dynamic selection between two-step and four-step RACH procedures based on real-time channel conditions and message contention status. The terminal device monitors downlink message quality and uplink message transmission success, then adaptively chooses the appropriate RACH procedure type, making the system flexible rather than static.
Solution Approach 2:
The patent changes the parameter of RACH procedure type (two-step vs. four-step) based on measured channel conditions and contention levels. When downlink message quality is good and contention is low, the system switches to two-step procedure to reduce latency; when conditions deteriorate, it switches to four-step procedure to maintain stability.
2Reliability
If a four-step RACH procedure is used, then stability is maintained, but latency increases
Solution Approach 1:
The system dynamically adjusts the RACH procedure type based on real-time conditions. When channel quality is poor or contention is high, the terminal device selects the four-step procedure to ensure stability through additional confirmation messages, then transitions to two-step when conditions improve, optimizing performance adaptively.
Solution Approach 2:
The terminal device performs preliminary assessment of downlink message quality and uplink transmission status before selecting the RACH procedure type. This preliminary evaluation allows the system to choose the optimal procedure in advance, avoiding unnecessary latency while maintaining stability when needed.
3Loss of time
If selective RACH procedure choice is implemented, then both stability and latency reduction are achieved, but device complexity increases
Solution Approach 1:
The terminal device implements feedback mechanisms to monitor downlink message quality and uplink message transmission success. Based on this feedback, the device automatically selects the appropriate RACH procedure type, reducing the need for complex manual configuration while achieving optimal performance.
Solution Approach 2:
The terminal device performs self-assessment of channel conditions and contention status, then autonomously selects the optimal RACH procedure type without requiring complex network configuration or manual intervention. This self-service approach reduces overall system complexity while maintaining optimal performance.
Data Source
AI summary
A method and corresponding terminal device including a selector that selects, in a RACH procedure, whether to transmit a first uplink message or a second uplink message to a base station device, the first uplink message being an uplink message of a two-step RACH procedure, the second uplink message being an uplink message of a four-step RACH procedure.