RACH Occasion Selection With SSB Mapping and RA-RNTI Disambiguation

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Solution Overview

Problem

Existing wireless communication networks face challenges in unambiguously configuring and selecting random access channel (RACH) occasions, particularly when additional features like RedCap and SDT are introduced, leading to potential collisions and inefficiencies in random-access procedures.

Innovation Solution

The solution involves configuring dedicated SSB-to-PRACH occasion mappings and prioritization mechanisms to ensure non-overlapping and unambiguous use of PRACH occasions for different UE types, using separate time and frequency domain configurations, and applying offset calculations to resolve RA-RNTI ambiguities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If additional features like RedCap and SDT are introduced to enhance network functionality, then network versatility and adaptability are improved, but collision probability and configuration ambiguity in RACH occasions increase

Engineering Contradiction:

Improvenetwork functionalityVSAvoidcollision probability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent segments RACH occasions into distinct sets for different UE types (legacy UEs versus RedCap/SDT UEs). By dividing the RACH resource space and applying type-specific selection rules, the system accommodates multiple features without causing collisions, thus resolving the contradiction between network versatility and collision probability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent applies different RACH occasion selection criteria and configuration parameters tailored to specific UE types. RedCap/SDT UEs use differentiated rules compared to legacy UEs, allowing each category to operate optimally in its designated resource space, thereby maintaining reliability while supporting diverse functionalities

Inventive Principle:

Principle #3Local quality

2Measurement precision

If separate configurations are applied for different UE types, then configuration precision and access reliability are improved, but device complexity and configuration management difficulty increase

Engineering Contradiction:

Improveconfiguration precisionVSAvoidconfiguration complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent introduces specific configuration parameters such as ra-ssb-OccasionMaskIndex and ssb-SharedRO-MaskIndex that control RACH occasion selection behavior. By modifying these parameters based on UE type, the system achieves precise configuration control while managing complexity through standardized parameter sets that can be applied systematically

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If RA-RNTI calculation uses standard formulas, then compatibility with legacy systems is maintained, but ambiguity arises in multi-features scenarios

Engineering Contradiction:

Improvesystem compatibilityVSAvoidRA-RNTI ambiguity

Core Design Contradiction:

Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent introduces the ssb-SharedRO-MaskIndex as an intermediary parameter that modifies the RA-RNTI calculation process. This intermediary element resolves ambiguity by providing UE-type-specific adjustments to the standard formula, maintaining compatibility while eliminating confusion in multi-feature scenarios

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentUS20250351189A1Technologies for random-access channel occasion selection

Publication Date: 2025.11.13 APPLE INC

AI summary

The present application relates to devices and components including apparatus, systems, and methods for configuring and selecting random access channel (RACH) occasions.