RACH Configuration Table for 5G Signaling Overhead Reduction
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Solution Overview
Problem
In the 5G wireless communication system, indicating available RACH resources to user apparatuses is inefficient due to high signaling overhead, requiring specification of positions in both time and frequency domains, preamble indexes, and associated SS blocks, which complicates the initial access process.
Innovation Solution
The solution involves using a RACH configuration table to indicate available RACH resources by excluding unavailable resources based on DL/UL assignments and SS block arrangements, allowing the user apparatus to identify suitable resources efficiently, and defining separate RACH configuration tables for different PRACH sub-carrier spacings to adapt to varying frequency bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the entire information for specifying the RACH resources is indicated to the user apparatus, then the user apparatus can accurately identify available RACH resources, but the signaling overhead increases
Solution Approach 1:
The patent extracts only the essential information needed for RACH resource identification from the complete resource specification. Instead of indicating all RACH resource parameters (time positions, frequency positions, preamble indexes, associated SS blocks), the invention transmits a compact RACH configuration table index that points to pre-defined resource configurations, thereby reducing signaling overhead while maintaining identification accuracy.
Solution Approach 2:
The patent inverts the traditional signaling approach by having the network pre-configure comprehensive RACH resource tables and then indicating only the index to the appropriate table configuration, rather than transmitting complete resource specifications. This inversion transforms a high-overhead detailed indication into a low-overhead index-based reference system.
2Adaptability or versatility
If the RACH resources are associated with multiple SS blocks and DL/UL configurations, then the resource allocation becomes flexible and adaptive, but the device complexity increases
Solution Approach 1:
The patent segments the RACH resource configuration into multiple independent dimensions: time domain positions, frequency domain positions, preamble indexes, and associated SS block indices. Each dimension can be independently configured and indicated through the RACH configuration table, allowing flexible combination without increasing overall system complexity.
Solution Approach 2:
The RACH configuration table serves multiple functions simultaneously: it defines time resources, frequency resources, preamble assignments, and SS block associations all in one unified structure. This multi-functional table approach consolidates what would otherwise require multiple separate configuration mechanisms, reducing device complexity while maintaining adaptability.
Data Source
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AI summary
A user apparatus communicates with a base station apparatus via a radio frame. The user apparatus includes a reception unit configured to receive information related to a RACH configuration table that indicates allocation of RACH resources in the time domain in the radio frame and information used for excluding unavailable RACH resources of the radio frame in the time domain, a control unit configured to identify available RACH resources based on the information related to the RACH configuration table and the information used for excluding unavailable RACH resources, and a transmission unit configured to transmit a preamble to the base station apparatus by using the identified available RACH resources.