Adaptive PRACH Repetition and Power for Faster NR Random Access

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Solution Overview

Problem

Existing wireless communication systems, particularly in 5G networks, lack effective methods for determining random access channel resources and transmission power for multiple physical random access channel transmissions, leading to inefficiencies in coverage enhancement and connection times for UEs in challenging environments.

Innovation Solution

A method for determining the number of physical random access channel (PRACH) transmissions and associated resources based on channel information, allowing UEs to adapt transmission power and repetition levels for improved connection establishment, including mechanisms for power ramping and resource allocation in different coverage modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple PRACH transmissions are performed to enhance coverage, then connection reliability is improved, but connection time increases

Engineering Contradiction:

Improveconnection reliabilityVSAvoidconnection time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by making the number of PRACH transmissions adaptive rather than fixed. The UE dynamically determines the number of transmissions based on measured downlink quality (RSRP) and compares it against thresholds to decide whether to perform 1, 2, or more transmissions, thereby optimizing the balance between reliability and time according to actual channel conditions

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of transmission repetition level based on channel quality measurements. By measuring downlink quality (RSRP) and using this information to determine the appropriate number of PRACH transmissions, the system adjusts the repetition parameter dynamically to achieve reliable connections without unnecessary time consumption in good coverage conditions

Inventive Principle:

Principle #35Parameter changes

2Reliability

If transmission power is increased for coverage enhancement, then connection reliability is improved, but energy consumption increases

Engineering Contradiction:

Improveconnection reliabilityVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent applies parameter changes by adjusting the number of transmissions based on measured downlink quality. When RSRP is above the first threshold (good coverage), the UE performs only 1 transmission with lower energy consumption. When RSRP is below the first threshold but above the second threshold (intermediate coverage), the UE performs 2 transmissions. This dynamic parameter adjustment optimizes the balance between reliability and energy consumption according to actual channel conditions

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20260012979A1Determination of random access channel resource and transmission power for multiple physical random access channel transmissions

Publication Date: 2026.01.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

During a random access (“RA”) procedure associated with a network node of a new radio (“NR”) communications network, a communication device can determine information associated with at least one of the communication device and a channel between the communication device and the network node. The communication device can further determine a number of physical RA channel (“PRACH”) transmissions to transmit to the network node prior to receiving a random access response as part of the RA procedure based on the information. The communication device can further transmit the number of PRACH transmissions to the network node as part of the RA procedure.