Preamble-to-PRU Mapping for Flexible Two-Step Random Access
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Solution Overview
Problem
The existing 5G NR technology lacks flexibility in managing various payload sizes and cell coverage requirements in two-step random access procedures, necessitating improvements in modulation coding schemes and resource allocation for uplink shared channel transmissions.
Innovation Solution
A one-to-many mapping arrangement is introduced between preambles and physical uplink shared channel resource units (PUSCH) to support configurable modulation coding schemes, piggybacking uplink control information, frequency hopping, and multiple-slot repetition, enhancing coverage and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed one-to-one mapping between preambles and PUSCH resource units is used, then the random access procedure is simple, but the system lacks flexibility to support various payload sizes and cell coverage requirements
Solution Approach 1:
The patent segments the PUSCH resource units into multiple groups (first PUSCH resource unit group and second PUSCH resource unit group) with different resource configurations. Each group can be further divided into multiple PUSCH resource units, allowing flexible allocation matching different payload sizes and coverage requirements while maintaining manageable system complexity through structured organization.
Solution Approach 2:
The patent introduces dynamic mapping relationships where preambles can be mapped to different PUSCH resource unit groups based on coverage requirements and payload characteristics. The mapping is not fixed but can be dynamically configured through RRC signaling, enabling the system to adapt to varying operational conditions while providing clear configuration rules to maintain complexity control.
2Reliability
If multiple PUSCH resource unit groups are configured for different coverage requirements, then coverage and reliability are improved, but the configuration and management complexity increases
Solution Approach 1:
The patent applies local quality by configuring different PUSCH resource unit groups with specific local characteristics (different resource configurations, time-frequency resources) tailored to specific coverage requirements. Each group is optimized for its intended use case, allowing the system to achieve reliable communication across different coverage scenarios without requiring all resources to be uniformly configured.
Solution Approach 2:
The patent uses RRC signaling as an intermediary mechanism to convey the mapping relationships between preambles and PUSCH resource unit groups to the UE. This intermediary configuration mechanism allows the network to dynamically manage complex multi-group configurations while providing clear, standardized instructions to the UE, thereby reducing the operational complexity at the user equipment level.
3Reliability
If frequency hopping and multiple-slot repetition are enabled, then frequency diversity and coverage are enhanced, but the transmission time and resource consumption increase
Solution Approach 1:
The patent enables partial frequency hopping and multiple-slot repetition based on the specific coverage requirements and payload characteristics. Rather than always using maximum frequency hopping and repetition, the system can apply these techniques partially or selectively to achieve sufficient frequency diversity and coverage enhancement while minimizing the associated time overhead and resource consumption.
Data Source
AI summary
Aspects are provided to support payloads for msgA transmission in a two-step random access (RACH) procedure by providing a one-to-many mapping arrangement between preambles and physical uplink shared channel (PUSCH) resource units (PRUs). A preamble is determined by the UE which is mapped to one or more groups of PRUs to support piggybacking of uplink control information (UCI), frequency hopping on PUSCH, and multiple-slot repetition for msgA transmissions. By piggybacking UCI to a payload in msgA, flexibility may be provided in the selection of MCS and waveform as well as resource allocation for demodulation reference signals (DMRS) and PUSCH in PRUs. Moreover, by allowing a payload to hop to different frequencies on PUSCH during the transmission of msgA, a gain in frequency diversity and interference averaging may be provided, and by enabling a payload to repeat across multiple slots in msgA transmission, coverage enhancement and/or reliability may be increased.