SS Block Timing Adjustment for NR-U Channel Access
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently accessing unlicensed bands, particularly in 5G networks, due to uncertainties in channel availability and regulatory requirements, leading to performance degradation in synchronization signal detection and paging message transmission.
Innovation Solution
The proposed solution involves optimizing synchronization signal (SS) blocks and Physical Broadcast Channel (PBCH) configurations to meet OCB and PSD requirements, using higher subcarrier spacing, interlaced structures, and hybrid approaches that combine multiple SS/PBCH blocks in frequency domain with FDM, to ensure compliance with regulatory limits and improve detection reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SS/PBCH blocks are transmitted in unlicensed bands using conventional methods, then initial access and synchronization can be established, but performance degrades due to channel availability uncertainties and regulatory compliance issues
Solution Approach 1:
The patent performs Listen Before Talk (LBT) procedure before transmitting SS/PBCH blocks to ensure channel availability. The time gap between failed and successful LBT is predetermined and used to adjust transmission timing, allowing the system to prepare in advance for potential channel unavailability and regulatory compliance requirements.
Solution Approach 2:
The patent dynamically adjusts SS/PBCH block transmission timing based on LBT outcomes. When LBT fails, the transmission is deferred by a predetermined time gap; when LBT succeeds, transmission proceeds immediately. This dynamic adaptation to channel conditions improves detection reliability while managing access complexity.
2Reliability
If SS/PBCH blocks are transmitted immediately after channel access, then transmission latency is reduced, but detection reliability decreases due to timing uncertainties
Solution Approach 1:
The patent establishes predetermined time gaps between failed LBT and subsequent successful LBT attempts. This preliminary timing arrangement ensures that when channel access is eventually successful, the SS/PBCH blocks can be transmitted at known, reliable time points, improving detection reliability while minimizing unnecessary delays.
Solution Approach 2:
The patent changes the transmission timing parameter based on LBT success/failure status. By adjusting the time offset from a baseline position according to the number of failed LBT attempts, the system optimizes the balance between transmission latency and detection reliability.
3Measurement precision
If cyclic rotation is applied to SS/PBCH blocks to indicate timing information, then frame timing determination is improved, but signal processing complexity increases
Solution Approach 1:
The patent uses cyclic rotation of SS/PBCH blocks as an encoding mechanism to indicate frame timing information. Different rotation amounts correspond to different timing indications, allowing the receiver to determine frame timing by detecting the rotation pattern. This approach embeds timing information in the signal structure itself, improving measurement precision while keeping processing relatively simple through correlation-based detection.
Data Source
AI summary
Methods, systems, and apparatuses for use in wireless communication are disclosed. A method of communication on an unlicensed band may include detecting a Synchronization Signal/Physical Broadcast Channel (SS/PBCH) block comprising a demodulation references signal (DMRS), a synchronization signal (SS), and a PBCH payload. A SS/PBCH block index may be obtained from one of the DMRS and the PBCH payload. A cyclic rotation indicator may be obtained from the SS/PBCH block (e.g., from the DMRS, the SS, and/or the PBCH payload). A determination may be made that the cyclic rotation indicator indicates an on state and a time gap may be obtained from one of the DMRS and the PBCH payload, based on the determination. Frame timing may be determined based on the cyclic rotation indicator, the SS/PBCH block index, and the time gap.