Wake-Up Signal Frequency Division Multiplexing with SSB in 5G NR-U

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Solution Overview

Problem

In 5G NR-U systems, the introduction of a wake-up signal to reduce power consumption and prevent paging loss due to listen before talk (LBT) requirements leads to resource wastage, especially in multiple-beam scenarios, where traditional methods of transmitting wake-up signals separately occupy excessive resources and cause paging loss.

Innovation Solution

Configuring a time-frequency position for the wake-up signal within a synchronization signal block (SSB) to enable frequency division multiplexing, allowing the wake-up signal to be transmitted only when the channel energy is below a threshold, and providing an alternative position for transmission when the channel is busy, thereby optimizing resource usage and reducing paging loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the wake-up signal is transmitted separately before paging occasion, then it can help UE detect signal and reduce power consumption, but it will occupy a lot of resources especially in multiple-beam scenarios

Engineering Contradiction:

Improvepower consumption of UEVSAvoidresource occupation

Core Design Contradiction:

Use of energy by moving objectVSQuantity of substance

Solution Approach 1:

The patent merges the wake-up signal transmission with the SSB transmission by frequency division multiplexing. The wake-up signal is transmitted in the same time domain symbol range as the SSB but in different frequency resources, allowing both signals to be transmitted together without occupying separate time-frequency resources. This resolves the contradiction by eliminating the need for separate wake-up signal transmission while still enabling UE power saving functionality.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If the wake-up signal is transmitted separately to reduce power consumption, then UE can detect paging more efficiently, but it causes paging loss due to LBT requirements in NR-U systems

Engineering Contradiction:

Improvepaging delivery reliabilityVSAvoidpower consumption of UE

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

The patent combines wake-up signal transmission with SSB transmission in the same time slot but different frequency resources. This merging allows the base station to perform LBT once for the combined transmission, avoiding the need for separate LBT attempts that would cause paging loss. The UE detects the wake-up signal within the SSB period, maintaining reliability while reducing power consumption.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The wake-up signal is transmitted in advance within the SSB period before the actual paging transmission. This preliminary action allows the base station to perform LBT and prepare the channel early, ensuring that subsequent paging transmissions can proceed without loss. The UE detects this early signal and prepares for potential paging, maintaining reliability while enabling power saving.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the wake-up signal is transmitted in form of sequence, then it can produce synchronization effect beneficial for NR-U, but it requires meeting LBT or OCB requirements which causes paging loss

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidpaging loss time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges wake-up signal transmission with SSB transmission in the same time slot. Since SSB transmission already includes necessary synchronization sequences and meets regulatory requirements, combining the wake-up signal with SSB allows the synchronization function to be achieved without separate LBT attempts, thereby eliminating paging loss while maintaining synchronization reliability.

Inventive Principle:

Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the transmission efficiency of the wake-up signal, effectively solving the problem of paging loss caused by LBT and reducing power consumption by ensuring the wake-up signal is transmitted only when necessary, thus conserving resources and minimizing frequent demodulation of paging messages on the PDCCH.

Implementation Method 1

a frequency-domain position for the wake-up signal is frequency division multiplexed with the current SSB

Methodology Applied

Scientific EffectFrequency division multiplexing:

Implementation Method 2

performing, before transmitting the wake-up through a channel wherein the time-frequency position is located, energy detection on the channel for a preset time interval

Methodology Applied

Scientific EffectEnergy detection:

Data Source

PatentUS11589308B2Method and device for transmitting wake-up signal, and method and device for paging demodulation

Publication Date: 2023.02.21 BEIJING XIAOMI MOBILE SOFTWARE CO LTD

AI summary

A method for transmitting a wake-up signal includes: if it is determined that the wake-up signal needs to be transmitted within a current synchronous broadcast block (SSB) period, configuring a time-frequency position for the wake-up signal, a frequency-domain position of the wake-up signal being frequency-division multiplexed with the current SSB, and a time domain position of the wake-up signal being located within a time domain symbol range of the current SSB; transmitting the time-frequency position of the wake-up signal to the UE; and sending the wake-up signal at the time-frequency position.