Multi-Beam RACH Configuration via SSB Preamble Mapping
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Solution Overview
Problem
In 5G communication systems, particularly in the 3GPP NR system, there is a challenge with random access channel (RACH) resource configuration and synchronization signal block (SSB) association in multi-beam systems, leading to beam mismatching issues, increased signaling overhead, and delays due to the complexity of beam management and resource allocation.
Innovation Solution
A method for setting RACH and SSB resource association in a multi-beam system that allows for flexible Rx beam switching, uses identical mapping for independent Rx beams, provides minimum system information for RACH setting, and reduces signaling overhead by associating multiple SSBs with preambles across multiple RACH resources, thereby addressing beam mismatching and optimizing resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple SSBs are associated with multiple preambles across multiple RACH resources in a multi-beam system, then beam mismatching problems are solved and random access efficiency is improved, but signaling overhead and system complexity increase
Solution Approach 1:
The patent segments the RACH resources and preambles into multiple groups, each associated with specific SSBs (synchronization signal blocks). This segmentation allows the system to handle beam matching by dividing the large-scale RACH configuration into smaller, manageable subsets, where each subset corresponds to a specific beam direction or SSB, thereby reducing the complexity of overall resource management while maintaining reliable beam matching.
Solution Approach 2:
The patent introduces dynamic beam switching capabilities where the base station can switch between different Rx (receive) beams to receive RACH preambles from UEs (user equipment). This dynamic beam switching allows the system to adapt to different spatial directions and resolve beam mismatching issues, improving reliability without requiring static complex configurations for all possible beam directions.
2Reliability
If flexible Rx beam switching is implemented to handle beam mismatching, then random access success rate improves, but processing time and system delay increase
Solution Approach 1:
The patent performs preliminary beam sweeping and SSB transmission before the actual random access procedure. The base station transmits multiple SSBs in different beam directions in advance, allowing UEs to identify the best downlink beam. This preliminary action enables the UE to select an appropriate preamble and RACH resource, reducing the need for extensive beam switching during the critical random access phase and thereby minimizing access delay.
Solution Approach 2:
The patent allows the system to skip certain beam switching steps when not necessary. If the UE successfully receives an SSB and identifies a suitable beam, the system can proceed directly to preamble transmission without additional beam switching delays. This skipping mechanism rushes through unnecessary steps, maintaining high random access success rates while minimizing processing time.
3Ease of manufacture
If identical mapping method is used for independent Rx beams, then configuration simplicity improves, but adaptability to different beam scenarios decreases
Solution Approach 1:
The patent designs a universal RACH resource mapping framework that can handle multiple beam scenarios using the same basic mapping principles. The identical mapping method uses a unified approach to associate SSBs with RACH resources and preambles, which can be applied regardless of the specific number of Tx (transmit) or Rx beams. This universality provides configuration simplicity while maintaining adaptability through parameters that can be adjusted to match different beam scenarios.
Solution Approach 2:
The patent employs parameter changes to adapt the identical mapping method to different beam scenarios. By modifying parameters such as the number of SSBs, the number of RACH resources, and the association patterns, the system can accommodate various configurations (e.g., different numbers of Tx and Rx beams) while maintaining the same fundamental mapping methodology. This allows flexible adaptation without requiring fundamentally different mapping approaches for each scenario.
4Reliability
If RACH resources are allocated in frequency domain with diversity, then robustness against interference improves, but resource allocation complexity increases
Solution Approach 1:
The patent allocates RACH resources across multiple dimensions, particularly utilizing the frequency domain as an additional dimension beyond time and spatial domains. By distributing RACH preambles across different frequency resources associated with different SSBs, the system achieves frequency diversity that provides robustness against frequency-selective fading and interference. This multi-dimensional resource allocation approach improves reliability while managing complexity through structured organization.
Data Source
AI summary
A method of performing, by a device, a random access procedure in a radio communication system includes: receiving from a base station RACH configuration information; and transmitting a first message based on the received RACH configuration information. Herein, a plurality of SSBs may be in association with a plurality of preambles, and the first message may be transmitted in a time domain through a plurality of RACH resources.