Random Access Preamble Transmission Using Beam-Resource Mapping
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Solution Overview
Problem
In radio communication systems, the application of beamforming in random access procedures is challenging due to the uncertainty of which resource to use for reporting a RA preamble, leading to potential failures in executing the random access procedure.
Innovation Solution
The technique involves associating RACH resource subsets with BS transmission beams, allowing the user apparatus to select and transmit RA preambles using corresponding resources, and the base station to determine the optimal BS transmission beam based on received RA preambles, thereby ensuring successful random access execution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If beamforming is applied in the random access procedure, then reception quality is improved, but it becomes unclear which resource to use for reporting a RA preamble
Solution Approach 1:
The RACH resources are segmented into multiple RACH resource subsets, where each subset is associated with a specific beam. This segmentation allows the terminal to select an appropriate resource subset based on the detected beam, resolving the ambiguity of resource selection while maintaining beamforming benefits.
Solution Approach 2:
The base station performs preliminary action by notifying the terminal of the association between RACH resource subsets and beams before the random access procedure. This advance information enables the terminal to make informed resource selection without confusion during the actual access process.
2Reliability
If multiple beams are used for signal transmission, then coverage and reliability are improved, but the complexity of determining the optimal beam increases
Solution Approach 1:
The terminal performs self-service by autonomously determining the optimal beam through detection and automatically selecting the corresponding RACH resource subset based on the detected beam. This eliminates the need for complex base station coordination during the actual random access, reducing overall system complexity while maintaining reliability.
Solution Approach 2:
The base station provides feedback by notifying the terminal of the beam-resource associations. This feedback mechanism guides the terminal's beam selection process, making it simpler for the terminal to determine the optimal beam without having to analyze multiple beams independently.
3Measurement precision
If beam search is performed to determine transmission beam direction, then reception quality is improved, but the time required for beam determination increases
Solution Approach 1:
The base station performs preliminary action by pre-establishing and notifying the terminal of the associations between beams and RACH resource subsets. This allows the terminal to skip extensive beam search during random access and directly select resources based on detected beams, significantly reducing beam determination time while maintaining accuracy.
Data Source
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AI summary
A user apparatus in a radio communication system including a base station and the user apparatus, including: a reception unit configured to receive a plurality of predetermined signals transmitted from the base station using a plurality of beams; and a transmission unit configured to transmit a preamble using a plurality of resources corresponding to the plurality of beams, wherein the reception unit receives, from the base station, system information including information of the plurality of resources corresponding to the plurality of beams, and the transmission unit obtains the information of the plurality of resources from the system information.