Ambient Power Wi-Fi Uplink Triggering With Backscatter PPDUs

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Solution Overview

Problem

Current IEEE 802.11 protocol is not applicable to ambient power (AMP) IoT devices that lack power or have low power, limiting their communication capabilities.

Innovation Solution

A wireless communication method involving the transmission of a downlink physical layer protocol data unit (PPDU) with a trigger indication to AMP non-AP stations (STAs) for uplink transmissions, utilizing backscatter-modulating waveforms and excitation fields to enable power provision and modulation, and employing CTS-to-Self mechanisms for link protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If IEEE 802.11 protocol is used for communication, then communication standardization is achieved, but AMP IoT devices without power or with low power cannot communicate effectively

Engineering Contradiction:

Improvecommunication capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent replaces traditional active transmission mechanisms with backscatter communication, where the AMP STA modulates reflected signals from DL PPDUs rather than generating independent transmission signals, enabling power-free or low-power operation while maintaining IEEE 802.11 compatibility

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent extends IEEE 802.11 protocol functionality to support multiple STA types (battery-powered, energy-harvesting, and backscatter STAs) through unified DL PPDU formats and trigger-based UL transmission mechanisms, making the system universally applicable across different power scenarios

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Use of energy by moving object

If backscatter communication is implemented for AMP STAs, then power consumption is reduced, but channel access and collision avoidance become problematic

Engineering Contradiction:

Improvepower consumptionVSAvoidchannel access reliability

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent implements trigger-based UL transmission where the AP sends trigger indications in DL PPDUs to explicitly grant channel access to AMP STAs, and STAs provide feedback through backscattered signals, creating a reliable controlled access mechanism that prevents collisions

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent uses CTS-to-Self frames sent by the AP before DL PPDU transmission to preliminarily reserve the channel and notify AMP STAs of upcoming transmissions, enabling them to prepare for triggered UL transmissions and avoid channel conflicts

Inventive Principle:

Principle #10Preliminary action

3Ease of operation

If trigger-based UL transmission is enabled for AMP STAs, then uplink communication is achieved, but synchronization and signal detection become challenging

Engineering Contradiction:

Improveuplink transmission capabilityVSAvoidsignal detection difficulty

Core Design Contradiction:

Ease of operationVSDifficulty of detecting and measuring

Solution Approach 1:

The patent includes synchronization fields and known waveform patterns in DL PPDUs before trigger indications, allowing AMP STAs to preliminarily synchronize their clocks and configure their backscatter modulators, making subsequent triggered UL transmission detection easier for the AP

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent uses the DL PPDU waveform itself as an intermediary carrier that AMP STAs modulate through backscatter, rather than requiring separate UL carriers, simplifying the detection process since the AP can identify UL transmissions as modulations of the known DL waveform

Inventive Principle:

Principle #24Intermediary (Mediator)

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

Enables effective communication for AMP IoT devices by allowing trigger-based uplink transmissions and reducing channel collisions, suitable for backscattering-type STAs and bi-static backscattering scenarios.

Implementation Method 1

a type-3 AMP STA may be referred to as a backscattering-type AMP STA capable of receiving only DL PPDUs and generating UL transmissions by modulating a received DL waveform

Methodology Applied

Scientific EffectBackscatter modulation: Reflection

Implementation Method 2

the DL PPDU may include an excitation field before an AMP package... and the waveform of the excitation field is used for providing the power for the type-3 AMP STA

Methodology Applied

Scientific EffectElectromagnetic energy harvesting: Electromagnetic Induction

Data Source

PatentUS20250344214A1Wireless communication method for ambient power

Publication Date: 2025.11.06 MEDIATEK INC

AI summary

A wireless communication method includes: transmitting, by a device, a downlink (DL) physical layer protocol data unit (PPDU) to an ambient power (AMP) non-access point (AP) station (STA), wherein the DL PPDU includes a trigger indication for triggering the AMP non-AP STA to perform an uplink (UL) transmission; and receiving, by the device, a backscattering UL transmission from the AMP non-AP STA in response to the trigger frame comprised in the DL PPDU.