PRACH Occasion Validation Under Adaptive SSB Periodicity

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Solution Overview

Problem

Adapting synchronization signal block (SSB) periodicity in a time domain for network energy savings poses challenges, as it can invalidate or validate physical random access channel (PRACH) occasions, disrupting legacy operations and SSB-RO mapping.

Innovation Solution

Techniques for determining valid PRACH occasions based on changes to SSB periodicity, ensuring that PRACH occasions remain valid or invalid without disrupting SSB-RO mapping, by applying validation rules when indicated or reflected in system information blocks.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If SSB periodicity is adapted for network energy savings, then energy efficiency is improved, but PRACH occasion validity is disrupted

Engineering Contradiction:

Improvenetwork energy consumptionVSAvoidPRACH occasion validity

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The patent implements dynamic SSB periodicity adaptation where the network can switch between different periodicities (e.g., 20ms, 40ms, 80ms) based on traffic conditions and energy requirements. The system dynamically determines valid PRACH occasions based on the current SSB periodicity through validation rules, allowing the network to optimize energy consumption while maintaining reliable random access procedures through adaptive reconfiguration.

Inventive Principle:

Principle #15Dynamics

2Adaptability or versatility

If SSB periodicity changes are implemented, then network adaptability is improved, but SSB-RO mapping stability deteriorates

Engineering Contradiction:

ImproveSSB periodicity flexibilityVSAvoidSSB-RO mapping consistency

Core Design Contradiction:

Adaptability or versatilityVSStability of the object's composition

Solution Approach 1:

The patent changes the periodicity parameter of SSB transmissions to adapt to different network conditions and energy requirements. By defining validation rules that map SSB indices to PRACH occasions based on the current periodicity, the system maintains stable SSB-RO mapping relationships even as the periodicity parameter changes, ensuring consistent random access behavior across different configuration scenarios.

Inventive Principle:

Principle #35Parameter changes

3Reliability

If validation rules are applied for PRACH occasion determination, then access reliability is improved, but system complexity increases

Engineering Contradiction:

ImproveRACH procedure reliabilityVSAvoidUE processing complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses indexing and mapping tables that predefine relationships between SSB indices and PRACH occasions. Instead of complex real-time validation, the UE copies or references pre-configured mapping relationships from system information, significantly reducing processing complexity while maintaining reliable determination of valid PRACH occasions through straightforward table lookups based on SSB periodicity.

Inventive Principle:

Principle #26Copying

Data Source

PatentUS20250317977A1Techniques for physical random access channel configuration under synchronization signal block adaptation in time domain

Publication Date: 2025.10.09 QUALCOMM INC

AI summary

Various aspects of the present disclosure generally relate to wireless communication. In some aspects, a user equipment (UE) may receive an indication associated with a change to a synchronization signal block (SSB) periodicity. The UE may determine one or more valid physical random access channel (PRACH) occasions based at least in part on the change to the SSB periodicity. The UE may mapping at least one SSB index to the one or more valid PRACH occasions. Numerous other aspects are described.