5G Terminal Initial Access Channel Configuration for High-Frequency Bands

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Solution Overview

Problem

In high-frequency bands beyond 52.6 GHz, such as FR4, the increased phase noise and propagation loss, along with sensitivity to peak-to-average power ratio (PAPR) and power amplifier nonlinearity, reduce the coverage and power spectral density of random access preambles, making initial access challenging in 5G New Radio (NR) systems.

Innovation Solution

A terminal is designed with a control unit that configures an initial access channel with a smaller number of resource blocks and a transmitting unit that transmits an initial access signal with increased subcarrier spacing (SCS) and new preamble formats, including a gap for antenna beam switching, to maintain power density and coverage in high-frequency bands.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a larger subcarrier spacing (SCS) is used in high-frequency bands, then the phase noise and propagation loss problems are mitigated, but the OFDM symbol length and SSB duration are decreased, reducing the reachable range of RA preamble

Engineering Contradiction:

Improvephase noise mitigationVSAvoidOFDM symbol length

Core Design Contradiction:

ReliabilityVSLength of moving object

Solution Approach 1:

The patent changes the subcarrier spacing parameter to a larger value in high-frequency bands to mitigate phase noise and propagation loss. This parameter change directly addresses the reliability issue while accepting the trade-off of shorter symbol length, which is compensated by other mechanisms in the system.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a larger subcarrier spacing (SCS) is used, then the phase noise problem is reduced, but the RA preamble length becomes short, limiting the cyclic shift amount and reducing the number of preamble patterns

Engineering Contradiction:

Improvephase noise reductionVSAvoidnumber of preamble patterns

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies parameter changes by adjusting the subcarrier spacing to larger values for high-frequency bands. This resolves the phase noise issue while the system compensates for the reduced number of preamble patterns through other configuration adjustments.

Inventive Principle:

Principle #35Parameter changes

3Use of energy by moving object

If the number of resource blocks is reduced in high-frequency bands, then the power spectral density is maintained, but the coverage range is decreased due to shorter transmission duration

Engineering Contradiction:

Improvepower spectral densityVSAvoidcoverage range

Core Design Contradiction:

Use of energy by moving objectVSLength of moving object

Solution Approach 1:

The patent changes multiple parameters including the number of resource blocks and subcarrier spacing to maintain power spectral density in high-frequency bands. These coordinated parameter changes address the energy usage issue while the system manages the coverage trade-off through appropriate configuration.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS20220369389A1terminal

Publication Date: 2022.11.17 NTT DOCOMO INC

AI summary

In a case of using a different frequency band that is different from a frequency band including one or a plurality of frequency ranges, a terminal sets an initial access channel configured with a smaller number of resource blocks than in a case of using the frequency band. The terminal transmits an initial access signal via the set initial access channel.