PRACH Format Configuration for Dynamic 5G Random Access

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Solution Overview

Problem

Existing wireless communication systems face challenges in efficiently configuring physical random access channels (PRACH) and radio network temporary identifiers (RNTI) in unlicensed and licensed spectrums, particularly in 5G networks, which affect network performance and connectivity.

Innovation Solution

The invention provides apparatus and methods for configuring PRACH formats and RNTIs in wireless networks, including 3GPP LTE and 5G networks, to enhance random access procedures and improve connectivity, especially in unlicensed spectrums using techniques such as dynamic selection and allocation of PRACH resources based on radio link measurements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If PRACH resources are statically allocated in unlicensed spectrum, then device connectivity is established, but network performance and throughput are degraded due to inefficient resource utilization

Engineering Contradiction:
Improvenetwork throughputVSAvoidPRACH configuration flexibility
Core Design Contradiction:
ProductivityVSAdaptability or versatility

Solution Approach 1:

The patent implements dynamic PRACH configuration where the base station selects and signals different PRACH formats (e.g., format 0, 1, 2, 3) based on real-time radio conditions, traffic load, and spectrum type (licensed vs. unlicensed). This allows the system to adapt PRACH resource allocation dynamically rather than using static configuration, thereby improving network throughput while maintaining adaptability.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system changes key PRACH parameters including format type, frequency location, time resources, and RNTI configuration based on measured radio link characteristics and network conditions. The base station signals these parameter changes to UEs through system information blocks or dedicated RRC messages, enabling optimized random access performance across different deployment scenarios.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If PRACH configuration is optimized for specific radio conditions, then access success rate improves, but system complexity increases due to multiple configuration options

Engineering Contradiction:
Improverandom access success rateVSAvoidUE configuration management
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system employs feedback mechanisms where UEs report radio link measurements (e.g., RSRP, channel quality) to the base station, which then determines the optimal PRACH configuration. The base station signals the selected configuration back to UEs, creating a closed-loop system that improves access success rate while centralizing the complexity management at the network side rather than in the UE.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The base station pre-configures multiple PRACH format options and RNTI values, then selects and signals the appropriate configuration before the random access procedure begins. This preliminary selection based on predicted or measured conditions reduces the complexity burden on UEs during the actual access process, as they simply follow the pre-determined configuration.

Inventive Principle:
Principle #10Preliminary action

3Adaptability or versatility

If multiple PRACH formats are supported for different scenarios, then system adaptability improves, but configuration management complexity increases

Engineering Contradiction:
ImprovePRACH format compatibilityVSAvoidconfiguration management
Core Design Contradiction:
Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent implements a universal PRACH configuration framework where a single base station and UE architecture supports multiple PRACH formats (0-3) and RNTI types (RA-RNTI, TC-RNTI, MCS-C-RNTI) through a unified configuration management mechanism. The base station selectively activates appropriate formats based on scenario requirements, providing multi-functionality without requiring separate dedicated systems for each format.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP3682707B1Physical random access channel (PRACH) format configuration
Publication Date: 2025.10.01 APPLE INC
  • EP3682707B1 patent drawingFigure 1A
  • EP3682707B1 patent drawingFigure 1B
  • EP3682707B1 patent drawingFigure 1C

AI summary

A user equipment (UE) can include processing circuitry configured to decode system information block (SIB) information including a PRACH configuration index. The PRACH configuration index indicates at least a first preamble format and a second preamble format. A PRACH preamble is encoded for transmission to a base station within a PRACH resource indicated by the PRACH configuration index. The PRACH preamble is associated with the first preamble format or the second preamble format. A random access channel response (RAR) message from the base station is decoded. The RAR message includes an uplink grant for scheduling a physical uplink shared channel (PUSCH) transmission. Data is encoded for transmission on the PUSCH based on the uplink grant. The PRACH resource comprises a plurality of PRACH occasions, where the PRACH preamble is transmitted within a PRACH occasion from the plurality of PRACH occasions with a starting symbol indicated by the PRACH configuration index.