User Equipment RAR Window Timing for Two-Step RACH
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Solution Overview
Problem
The two-step RACH procedure in NR wireless communication systems faces challenges in executing the RAR window operation appropriately due to potential deviations from the intended procedure, particularly when data is transmitted in a PUSCH resource before the completion of the preamble transmission.
Innovation Solution
The user equipment is configured to start the RAR window after the resource (preamble or PUSCH) that ends later in time domain, ensuring appropriate execution of the random access procedure by aligning with the intended two-step RACH flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If two-step RACH is used to reduce latency and power consumption, then random access speed is improved, but the reliability of RAR window operation deteriorates
Solution Approach 1:
The patent applies preliminary action by having the user equipment start the RAR window timing based on the later-ending resource (preamble or PUSCH) before actually needing to monitor the random access response. This ensures that the RAR window is properly positioned in time domain regardless of which resource completes first, preventing operational deviations and ensuring reliable RAR monitoring while maintaining the speed benefits of two-step RACH.
2Ease of operation
If RAR window is started after preamble transmission, then monitoring timing is simplified, but the risk of procedure deviation increases when PUSCH transmission is involved
Solution Approach 1:
The patent applies parameter changes by modifying the RAR window start timing parameter based on the actual resource completion time. Instead of using a fixed start time relative to preamble transmission, the system dynamically determines the RAR window start based on which resource (preamble or PUSCH) ends later in the time domain. This parameter adjustment ensures procedure accuracy while maintaining operational simplicity.
Data Source
AI summary
A user equipment includes a transmitting unit configured to transmit a message in a random access procedure by using a preamble resource and a PUSCH resource, and a control unit configured to start a time window for monitoring a random access response after a resource that is one of the preamble resource and the PUSCH resource whichever ends later in time domain.