Beam-Based Random Access Preamble Selection in Multi-Beam Systems
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Solution Overview
Problem
In communications systems using multiple beams, the existing random access procedures are inefficient due to high preamble detection time and computation requirements, especially in millimeter wave networks where channel attenuation and interference complicate preamble detection across multiple beams.
Innovation Solution
A method and apparatus that determine the best beam for communication by measuring signal quality and classify random access preambles into beam-based and cell-based groups, allowing for selective preamble transmission and response, reducing detection time and computation by prioritizing beam-based preambles under optimal conditions and switching to cell-based preambles if exceptions occur.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If existing random access procedures are used in multi-beam systems, then all beams can be covered, but preamble detection time and computation requirements increase significantly
Solution Approach 1:
The patent segments the random access procedure into two distinct paths: beam-based random access for initial access and cell-based random access for other scenarios. This segmentation allows the system to use different preamble detection strategies depending on the access type, reducing overall detection time while maintaining comprehensive beam coverage capability.
Solution Approach 2:
The patent performs preliminary beam measurement and selection before the random access procedure. The terminal measures downlink reference signals from multiple beams, identifies the best beam, and determines the appropriate preamble group (beam-based or cell-based) in advance. This preliminary action prevents the need for exhaustive preamble detection across all beams during the random access procedure.
2Adaptability or versatility
If existing random access procedures are used in multi-beam systems, then all terminals can access, but computation requirements increase
Solution Approach 1:
The patent divides preambles into two groups: beam-based preambles for terminals accessing via beam-specific resources and cell-based preambles for other cases. The base station only needs to detect preambles from the selected group rather than all preambles across all beams, significantly reducing computation requirements while maintaining universal terminal access capability.
Solution Approach 2:
The patent implements partial action by having the base station perform preamble detection only on the necessary subset of preambles based on the access type. For beam-based random access, detection is limited to beam-specific preambles; for cell-based random access, detection uses cell-wide preambles. This avoids the excessive computation of detecting all preambles from all beams in all scenarios.
3Productivity
If beam-based preambles are used for random access, then detection efficiency improves, but inter-beam interference may occur
Solution Approach 1:
The patent converts the potential harm of inter-beam interference into a benefit by using it as a criterion for selecting between beam-based and cell-based random access. When inter-beam interference is detected or predicted to be high, the system automatically switches to cell-based random access with cell-wide preambles that are designed to be more robust against interference, thus turning the interference condition into a trigger for a more appropriate access mode.
Solution Approach 2:
The patent introduces dynamic selection between beam-based and cell-based random access procedures. The terminal and base station adaptively choose the access mode based on current channel conditions, beam quality, and interference levels. This dynamic approach allows the system to optimize detection efficiency when conditions are favorable while switching to more robust cell-based access when interference becomes problematic.
Data Source
AI summary
In a communications system using a plurality of beams, a terminal determines a beam to be communicated with the terminal among the plurality of beams, determines one sequence among sequences allocated to the determined beam as a beam based random access preamble, and transmits the beam based random access preamble through the determined beam. In addition, if a random access response for the beam based random access preamble is not received from a base station for a set interval, the terminal determines one sequence among sequences in a cell based random access preamble collection as a cell based random access preamble and transmits the cell based random access preamble.