Reduced Capability NR Device Initial Access via PRACH Repetitions

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Solution Overview

Problem

Reduced capability New Radio (NR) devices face severe deterioration in downlink and uplink channel coverage due to limited processing power, smaller antenna numbers, and narrower bandwidth, necessitating improved access techniques.

Innovation Solution

The implementation of methods and apparatuses for reduced capability NR devices to receive reference signals and broadcast system information at a reduced frequency, determining coverage enhancements, and selecting random access channel occasions for PRACH repetitions to enhance communication with the base station, including the option to send PRACH repetitions in consecutive or non-consecutive slots and across different bandwidth parts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If reduced capability NR devices use narrower bandwidth and fewer antennas, then device complexity and power consumption are reduced, but downlink and uplink channel coverage are severely deteriorated

Engineering Contradiction:

Improvedevice complexityVSAvoidchannel coverage

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The base station performs preliminary actions by transmitting repeated broadcast system information messages before the reduced capability NR device needs to access the network. The device monitors these repeated messages at reduced frequency, and the base station determines coverage enhancement based on whether the device successfully receives the broadcast system information, enabling the device to identify itself and establish communication despite limited capabilities

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent applies parameter changes by modifying the monitoring frequency of broadcast system information from standard frequency to reduced frequency for reduced capability NR devices. The base station also adjusts the repetition configuration and coverage enhancement parameters dynamically based on the device's received signal strength and capability, allowing the device to operate successfully with narrower bandwidth and fewer antennas

Inventive Principle:

Principle #35Parameter changes

2Use of energy by moving object

If reduced capability NR devices monitor broadcast system information at reduced frequency, then power consumption is reduced, but the ability to timely acquire system information is worsened

Engineering Contradiction:

Improvepower consumptionVSAvoidtime to acquire system information

Core Design Contradiction:

Use of energy by moving objectVSLoss of time

Solution Approach 1:

The base station transmits broadcast system information messages repeatedly over multiple time periods, ensuring continuous availability of the information. The reduced capability NR device monitors these repeated messages at reduced frequency, and the base station determines coverage enhancement based on whether the device successfully receives the broadcast system information, enabling the device to acquire necessary information despite lower monitoring frequency

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The base station receives feedback from the reduced capability NR device regarding its coverage enhancement status and successfully receives the broadcast system information. Based on this feedback, the base station determines the appropriate repetition configuration and adjusts the communication parameters, allowing the device to acquire system information efficiently while consuming less power

Inventive Principle:

Principle #23Feedback

3Reliability

If reduced capability NR devices transmit PRACH repetitions in consecutive slots, then communication reliability is improved, but time efficiency is reduced

Engineering Contradiction:

Improvecommunication reliabilityVSAvoidtime efficiency

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent applies dynamics by allowing the base station to flexibly configure the timing and positioning of PRACH repetitions based on the specific needs of each reduced capability NR device. The base station determines coverage enhancement and selects appropriate random access channel occasions, enabling PRACH repetitions to be transmitted in consecutive slots when reliability is critical, or spaced apart when time efficiency is prioritized, adapting the approach dynamically to individual device requirements

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS20230188261A1Initial access for reduced capability new radio devices

Publication Date: 2023.06.15 IPLA HLDG INC

AI summary

Methods and apparatuses are described herein for reduced capability New Radio (NR) devices. A reduced capability NR device may receive, from a base station, a reference signal (RS) or broadcast system information. The reduced capability NR device may determine, based on the received RS or the received broadcast system information, a coverage enhancement for the wireless communications device and may determine a repetition configuration. The reduced capability NR device may select, based on the coverage enhancement and repetition configuration, a plurality of random access channel occasions (ROs) for a plurality of physical random access channel (PRACH) repetitions. The reduced capability NR device may send, based on one or more ROs of the selected plurality of ROs, one or more PRACH repetitions of the plurality of PRACH repetitions to cause the base station to identify the coverage enhancement and a type associated with the wireless communications device.