UE Random Access Preamble Transmission in NR-U
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Solution Overview
Problem
In NR-U systems, user equipment attempting to transmit a random access preamble may cause LBT failure due to interference from other uplink signals, leading to wasted random access resources and reduced transmission probability.
Innovation Solution
The method involves determining an available random access occasion and timing advance value, performing listen before talk (LBT) before the timing advance of the first available occasion, and transmitting the random access preamble if successful, with mechanisms to adjust timing advance values and counters based on failure conditions, and using frequency domain multiplexing to optimize resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If user equipment transmits random access preamble in NR-U system, then random access function is provided, but LBT failure occurs due to interference from other uplink signals
Solution Approach 1:
The patent applies preliminary action by performing LBT before the random access preamble transmission at a determined time point. The UE calculates a time point for performing LBT based on timing advance information and random access configuration, ensuring the channel is clear before transmission. This preliminary channel check prevents interference from other uplink signals and improves transmission success probability.
Solution Approach 2:
The patent implements dynamics by allowing flexible timing advance values and dynamic LBT timing. The UE can adjust the LBT timing based on received timing advance information and random access configuration, adapting the transmission timing to avoid interference while maintaining reliable random access functionality.
2Manufacturing precision
If timing advance is applied to align uplink signals, then signal alignment is improved, but LBT may fail due to advance timing interference
Solution Approach 1:
The patent performs LBT before applying timing advance alignment. By determining the LBT timing point based on timing advance information and performing the listen-before-talk procedure at this calculated time point, the system ensures channel clearance before signal alignment is applied, preventing LBT failure while maintaining timing precision.
3Device complexity
If random access resources are allocated without LBT, then resource allocation is simplified, but transmission probability is unfairly reduced
Solution Approach 1:
The patent introduces a determined time point for LBT that is calculated before random access resource allocation. By establishing this timing reference point based on timing advance and random access configuration, the system performs channel clearance efficiently without complicating the overall resource allocation process, thereby maintaining simple allocation mechanisms while improving transmission probability.
Data Source
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AI summary
The present disclosure provides a signal transmission/reception method, user equipment, and network equipment, the method including: determining, by a user equipment, an available random access occasion and a timing advance (TA) value; performing listen before talk (LBT) before a TA of the first available random access occasion; transmitting, if the LBT is successful, the random access preamble on the random access occasion.