Interlaced PRACH Configuration for NR-U Power Compliance
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Solution Overview
Problem
Current random access channel (RACH) designs for New Radio (NR) systems operating in unlicensed spectrum face challenges in efficiently utilizing transmission power and complying with occupied channel bandwidth regulations, particularly in the 5 GHz band, where transmissions over contiguous physical resource blocks (PRBs) are limited by power spectrum density constraints.
Innovation Solution
The configuration of PRACH over interlaced PRBs rather than contiguous PRBs allows for maximization of transmission power by allocating power across adjacent PRBs spaced at least 1 MHz apart, enabling compliance with occupied channel bandwidth regulations and improving power utilization in unlicensed spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If transmissions are made over contiguous physical resource blocks (PRBs) in unlicensed spectrum, then the transmission structure is simple and easy to implement, but the transmission power is limited by power spectrum density constraints and occupied channel bandwidth regulations
Solution Approach 1:
The patent segments the contiguous PRB structure into interlaced PRBs, where PRBs are distributed across different frequency subbands with at least 1 MHz spacing. This segmentation allows the system to comply with occupied channel bandwidth regulations while maximizing transmission power by allocating power across multiple separated frequency resources rather than being constrained by contiguous spectrum limitations.
2Power
If transmissions are made over interlaced physical resource blocks (PRBs) spaced at least 1 MHz apart, then transmission power is maximized and occupied channel bandwidth regulations are complied with, but the resource allocation complexity increases
Solution Approach 1:
The patent introduces dynamic PRACH resource allocation mechanisms where the network can configure multiple PRACH occasions with different interlaced PRB patterns. The system dynamically selects and switches between different PRACH resources based on channel conditions, traffic load, and regulatory requirements, making the complex interlaced structure adaptable and manageable through flexible configuration rather than static rigid allocation.
3Reliability
If multiple PRACH resources are configured in frequency domain to improve transmission reliability, then the reliability of preamble transmissions is enhanced, but the signaling overhead and configuration complexity increase
Solution Approach 1:
The patent merges multiple PRACH resource configurations into unified parameter sets that can be efficiently signaled. By grouping related PRACH parameters (such as frequency offsets, resource block allocations, and timing information) into consolidated configuration messages, the system reduces signaling overhead while maintaining the ability to configure multiple frequency-diverse PRACH resources for improved transmission reliability.
Data Source
AI summary
A network device (e.g., a user equipment (UE), or a new radio NB (gNB)) can process or generate a configuration of a physical random access channel (PRACH) over physical resource blocks (PRBs) that are interlaced in an unlicensed band in an NR unlicensed (NR-U) communication. The PRBs in the PRACH can be based on an occupied channel bandwidth (OCB) of the unlicensed band in the NR-U communication. A random access channel transmission in the PRACH can then be generated by interlacing the PRBs defining the PRACH.