NR Random Access Repetition for Reduced-Capability UEs
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Solution Overview
Problem
The 3GPP NR system lacks a specific method for random access of reduced capability (RC) user equipment (UE), which includes industrial wireless sensors, video surveillance, and wearable devices, requiring a new approach for random access and uplink data channel repetition transmission.
Innovation Solution
A method and apparatus for RC UE that involves receiving random access-related configuration information, determining PRACH and PUSCH repetition transmissions, and performing these transmissions based on determined resources, including ROs, POs, and DMRS information.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional random access methods are used for RC UE, then the system maintains compatibility with existing NR UEs, but RC UE cannot achieve reliable communication in challenging environments due to insufficient transmission robustness
Solution Approach 1:
The random access procedure is segmented into multiple repetition transmissions. The PRACH transmission is divided into multiple repetitions with different beam directions, and the PUSCH transmission is similarly segmented. This segmentation allows RC UE to transmit random access signals multiple times to overcome poor channel conditions without requiring a completely new complex random access protocol.
Solution Approach 2:
The patent implements periodic repetition transmissions where the same random access preamble and uplink data are transmitted at regular intervals using different beam directions. This periodic action ensures that at least one transmission will succeed in challenging environments while maintaining a manageable transmission pattern for RC UE.
2Reliability
If multiple beams are used for transmission to overcome poor channel environment, then communication reliability improves, but the complexity of beam management and resource allocation increases
Solution Approach 1:
The patent creates a universal random access framework that works for both conventional NR UEs and RC UEs. The same PRACH and PUSCH resources can be used by different UE types, with RC UE simply utilizing repetition transmissions. This multi-functionality approach allows multiple beam directions to be managed through a unified resource allocation scheme rather than separate complex management systems.
Solution Approach 2:
The network pre-configures multiple beam directions and associates them with specific PRACH occasions and PUSCH resources before random access occurs. RC UE can select appropriate beams based on pre-configured information and channel conditions, eliminating the need for complex real-time beam training and management during the random access procedure.
3Reliability
If RC UE performs repeated transmissions to overcome pathloss and frequency offset, then communication quality improves, but uplink resource consumption increases
Solution Approach 1:
The patent implements a configurable number of repetition transmissions rather than requiring all possible repetitions. The network can adjust the repetition count based on channel conditions and UE capability, performing only the necessary number of transmissions to achieve reliable communication. This partial action approach avoids excessive resource consumption while still overcoming pathloss and frequency offset effects.
Solution Approach 2:
The patent utilizes the beam dimension as an additional degree of freedom for resource allocation. Instead of consuming more time-frequency resources through repetitions, the system distributes transmissions across different spatial dimensions (beam directions). This dimensional change allows multiple transmissions to occur in parallel or with reduced time-frequency resource overlap, improving spectral efficiency.
Data Source
AI summary
A method for wireless communication between a plurality of devices includes determining the number of PUSCH repetition transmissions, determining a PUSCH transmission resource, based on random access-related configuration information and the number of PUSCH repetition transmissions, and performing the PUSCH repetition transmission based on the PUSCH transmission resource.