Two-Step NR Random Access in Unlicensed Bands With LBT Power Ramping
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Solution Overview
Problem
The challenge of initiating a 2-step random access procedure for a terminal device on an unlicensed band in NR systems is not adequately addressed, particularly in terms of power ramping mechanisms for signal transmission.
Innovation Solution
A 2-step random access method for unlicensed bands that involves determining LBT detection results to decide on sending msgA and updating power ramping and transmission counters, with separate or shared counters for PRACH and PUSCH, to improve spectrum utilization and communication efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If 2-step random access procedure is introduced on unlicensed band, then spectrum utilization and communication efficiency are improved, but the complexity of initiating the procedure and managing power ramping mechanisms increases
Solution Approach 1:
The patent segments the random access procedure into distinct phases: LBT detection phase, msgA transmission phase, and counter management phase. It separates the handling of PRACH and PUSCH with independent power ramping counters, allowing each component to be managed independently, thereby reducing overall initiation complexity while maintaining improved spectrum utilization through the 2-step procedure.
2Reliability
If power ramping mechanism is implemented for msgA transmission, then transmission reliability is improved, but the complexity of managing separate or shared counters for PRACH and PUSCH increases
Solution Approach 1:
The patent implements dynamic counter management where the system can flexibly switch between separate counters for PRACH and PUSCH, or use shared counters based on specific transmission conditions. The power ramping counter is dynamically updated based on LBT detection results and transmission outcomes, allowing the system to adapt counter management strategies to maximize transmission reliability while minimizing operational complexity.
Solution Approach 2:
The patent changes the parameter state of power ramping counters based on LBT detection results and transmission success/failure. When LBT succeeds, the counter is updated to reflect successful transmission; when LBT fails, the counter remains unchanged or is reset. This parameter-based approach simplifies counter management by using clear state transitions rather than complex management logic.
3Reliability
If LBT detection is performed before msgA transmission, then transmission success rate is improved, but the time required for random access procedure increases
Solution Approach 1:
The patent performs LBT detection as a preliminary action before msgA transmission, allowing the terminal to check channel availability in advance. This preliminary LBT detection, combined with the 2-step random access procedure that transmits both PRACH and PUSCH in a single opportunity, improves transmission success rate by avoiding unnecessary transmissions while the time overhead is minimized through efficient counter management and rapid sequential operations.
Data Source
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AI summary
Embodiments of this disclosure disclose a 2-step random access method and device for an unlicensed band. The method is executed by a terminal device and includes: determining, based on an LBT detection result, whether to send an msgA and whether to update a power ramping counter for the msgA, where the power ramping counter is used to determine transmission power for the msgA, and the msgA includes a PRACH and a PUSCH; and determining, based on a sending status of the msgA, whether to update a transmission counter for the msgA.