Multi-SSB PRACH Beamforming for Uplink Coverage

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Solution Overview

Problem

Existing communication systems face limitations in uplink (UL) coverage during PRACH transmissions due to the constraint of associating user equipment (UE) with a single synchronization signal reference (SSB) in multi-TRP scenarios, which restricts the utilization of PRACH resources and affects coverage.

Innovation Solution

Enhancing PRACH transmissions by aligning UE transmission with multiple SSBs from a single or multiple TRPs, utilizing beamforming and precoding strategies based on multiple SSB signals, and providing network indications for UL transmission types and resource information.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If UE is associated with a single SSB in multi-TRP scenarios, then the association constraint is simple, but UL coverage and PRACH resource utilization are limited

Engineering Contradiction:
ImproveUL coverageVSAvoidSSB association complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the SSB association by introducing a set of candidate SSBs that a UE can be associated with, rather than a single SSB. This segmentation allows the UE to select from multiple SSBs based on signal quality conditions, thereby improving UL coverage while managing complexity through structured selection criteria.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements dynamic SSB association where the UE can switch between different SSBs based on received signal quality conditions. The association is not fixed but adapts dynamically based on the measured signal quality, allowing flexible utilization of multiple TRPs for enhanced coverage.

Inventive Principle:
Principle #15Dynamics

2Reliability

If UE transmits PRACH based on a single SSB, then the transmission procedure is simple, but preamble detection performance and coverage are limited

Engineering Contradiction:
Improvepreamble detection performanceVSAvoidPRACH transmission complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple SSB-based PRACH transmissions by allowing a UE to transmit PRACH preambles associated with multiple candidate SSBs. This combining of multiple transmission paths improves preamble detection performance by providing multiple reference signals for the gNB to detect the preamble, while the patent manages complexity through defined selection conditions.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If multiple SSBs are used for PRACH transmission, then UL coverage and detection performance improve, but the PRACH configuration and selection process become more complex

Engineering Contradiction:
Improvenetwork resource utilizationVSAvoidPRACH configuration complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent utilizes parameter changes by defining specific conditions based on received signal quality (such as threshold values or ranges) that determine which SSBs a UE can be associated with. By changing the selection parameters based on measured signal quality, the system optimizes network resource utilization while providing clear criteria that manage configuration complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4642140A1Apparatus, method and computer program for performing a random access procedure
Publication Date: 2025.10.29 NOKIA TECHNOLOGIES OY
  • EP4642140A1 patent drawingFigure 1
  • EP4642140A1 patent drawingFigure 2
  • EP4642140A1 patent drawingFigure 3

AI summary

There is provided an apparatus comprising means for obtaining information related to a physical random access channel, PRACH, configuration, receiving, from at least one transmit receive point, a plurality of synchronization reference signals, selecting at least two synchronization reference signals from the plurality of received synchronization reference signals, determining a beamformer based on the selected at least two synchronization reference signal and performing PRACH transmission based on the PRACH configuration and the determined beamformer.