2-Step Random Access Signaling Window Adaptation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The 5G NR system's 2-step Random Access procedure experiences performance degradation when a UE selects an RA preamble not associated with a PRU, leading to longer access delays due to a longer RAR window compared to the 4-step RA procedure, which fails to meet the demand for normal access delay requirements.
Innovation Solution
A mechanism is introduced to establish an association between specific time windows and shared channel resource units, allowing the UE to monitor signals in either a first or second time window based on the association of the signature sequence with a shared channel resource unit, thereby reducing access delay performance to be comparable to the 4-step RA procedure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the RAR window in 2-step RA procedure is made longer to ensure reliable message reception, then the reliability of random access is improved, but the access delay increases and becomes longer than the 4-step RA procedure
Solution Approach 1:
The RAR window monitoring process is segmented into two distinct time windows: a first time window for monitoring UEs that transmitted PUSCH payloads, and a second time window for monitoring UEs that did not transmit PUSCH payloads. This segmentation allows the system to provide differentiated monitoring durations based on the UE's transmission behavior, ensuring reliable reception while optimizing access delay for different scenarios.
Solution Approach 2:
The monitoring window duration is made dynamic rather than fixed. The UE dynamically selects which time window to monitor based on whether it transmitted a PUSCH payload in its MsgA. This dynamic adaptation allows the system to adjust the effective RAR window length according to the specific transmission scenario, resolving the contradiction between reliability and access delay.
2Device complexity
If the UE always selects an RA preamble not associated with a PRU, then the device complexity is reduced, but the PUSCH payload cannot be transmitted and the access delay increases
Solution Approach 1:
The patent introduces an intermediary mechanism (the second time window and associated monitoring process) that enables UEs who did not transmit PUSCH payloads to still receive RAR responses. This intermediary structure allows the system to handle the case where PUSCH transmission is omitted or fails, maintaining access functionality without requiring complex PUSCH transmission logic in all cases.
3Measurement precision
If the RAR window start position is determined according to the PRU in MsgA, then the measurement precision of resource allocation is improved, but when the RA preamble is not associated with a PRU, the RAR window cannot determine the start position
Solution Approach 1:
The patent creates a universal RAR window determination mechanism that works for both types of RA preambles. The first time window uses the PRU-based start position determination for preambles associated with PUSCH resources, while the second time window provides an alternative start position determination for preambles not associated with PUSCH resources. This multi-functional approach ensures the system can handle all RA preamble types uniformly.
Data Source
AI summary
The present disclosure provides a method and a device in a node for wireless communications. The first node receives a first reference-signal-resource set; selects a first signature feature out of a candidate sequence group in a first period, transmits a first signature sequence on a first time-frequency resource block; when the first signature sequence is associated with a shared channel resource unit in the first period, monitors a second signal in the second time window; and when the first signature sequence is not associated with any shared channel resource unit in the first period, monitors a second signal in a second time window; measuring at the first reference-signal-resource set is used for determining a first channel quality; the first signature sequence is a candidate sequence in the candidate sequence group in the first period. The present disclosure ensures access delay demands of 2-step random access procedure.