Random Access Occasion Subsets for Beam Refinement
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Solution Overview
Problem
Current wireless communication systems face challenges in efficiently managing random access occasions, particularly in multi-beam operations, where a limited number of RACH occasions are configured before RAR reception, and UEs use different Tx beams for each transmission, leading to suboptimal beam refinement and reduced signal quality.
Innovation Solution
The method involves receiving a message from a base station indicating a set of random access occasions divided into subsets, each associated with a unique beam and synchronization signal, allowing the UE to transmit random access preambles within these subsets using corresponding beams, thereby enabling beam refinement and improving transmission quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If a limited number of RACH occasions are configured before RAR reception, then the random access procedure is simplified and faster, but beam refinement is suboptimal and signal quality is reduced
Solution Approach 1:
The patent divides the set of random access occasions into multiple subsets, where each subset is associated with a specific beam. This segmentation allows the UE to transmit preambles using different beams across different subsets, enabling beam refinement while maintaining a limited number of total RACH occasions. The base station can then identify the best beam based on the transmitted preambles and provide targeted RAR reception.
2Adaptability or versatility
If the UE uses different Tx beams for different RACH transmission occasions, then beam diversity is improved, but beam refinement is insufficient and signal quality deteriorates
Solution Approach 1:
The patent assigns specific beams to specific subsets of random access occasions, creating a localized beam-quality mapping. Each subset is associated with a particular beam, allowing the UE to use the optimal beam for transmissions within that subset. This local quality assignment enables the base station to receive preambles with focused signal energy, improving signal quality while maintaining beam diversity across different subsets.
3Reliability
If multiple random access preambles are transmitted across different subsets, then beam refinement is enabled, but the complexity of managing beam-subset associations increases
Solution Approach 1:
The patent configures the beam-subset associations in advance through system information broadcast by the base station. The UE receives configuration information that maps specific subsets to specific beams before the random access procedure begins. This preliminary action eliminates the need for real-time beam selection decisions, reducing the complexity of managing beam-subset associations during the actual random access transmission.
Data Source
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AI summary
Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive, from a base station, a message that indicates a plurality of subsets within a set of random access occasions. Each subset of the plurality of subsets may be associated with a corresponding beam of a plurality of beams, and each corresponding beam may be different from remaining beams of the plurality of beams. Accordingly, the UE may transmit, to the base station and based at least in part on the message, at least one random access preamble. The at least one random access preamble is transmitted within one or more subsets, of the plurality of subsets, using one or more corresponding beams of the plurality of beams. Numerous other aspects are described.