Adaptive Code Assignment for Ambient Power Stations

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Solution Overview

Problem

Current solutions fail to address the interference and contention issues faced by backscatter devices (BKDs) in Wi-Fi networks, as they do not provide guidance for permitting BKDs to function with minimal contention.

Innovation Solution

The method involves AMP stations using random timers and selecting orthogonal codes for backscatter communications, with the access point detecting collisions and transmitting retry messages to reset the timers and select new codes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If BKDs transmit whenever energy storage device has enough energy without waiting for AP instructions, then transmission timing flexibility is improved, but wireless medium contention and interference increase

Engineering Contradiction:

Improvetransmission timing flexibilityVSAvoidwireless medium contention

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The patent applies preliminary action by having BKDs perform clear channel assessment (CCA) and energy detection before transmitting. The BKD checks if the channel is idle for a specified duration (DIFS period) before initiating transmission, preventing collisions with ongoing transmissions from other devices. This preliminary checking mechanism allows flexible transmission timing while avoiding wireless medium contention.

Inventive Principle:

Principle #10Preliminary action

2Productivity

If multiple BKDs transmit backscatter signals simultaneously, then communication productivity is improved, but code collisions occur reducing reliability

Engineering Contradiction:

Improvecommunication throughputVSAvoidcommunication reliability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent applies segmentation by dividing the backscatter communication resource space into multiple orthogonal codes (e.g., Hadamard codes). Each BKD is assigned a unique orthogonal code, allowing multiple BKDs to transmit simultaneously without interference. The access point uses these orthogonal codes to separately decode transmissions from different BKDs, maintaining both high productivity and reliability through code division multiple access (CDMA).

Inventive Principle:

Principle #1Segmentation

3Device complexity

If current solutions focus on BKD as primary subject without coordination mechanisms, then device simplicity is improved, but network contention and interference increase

Engineering Contradiction:

ImproveBKD structure simplicityVSAvoidnetwork interference

Core Design Contradiction:

Device complexityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces the access point as an intermediary that coordinates backscatter communications. The AP assigns orthogonal codes to BKDs, manages transmission scheduling, and detects code collisions. This intermediary mechanism allows BKDs to maintain structural simplicity while the AP handles the complexity of resource allocation and conflict resolution, reducing overall network interference.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If orthogonal codes are assigned to multiple AMP STAs for parallel transmission, then communication efficiency is improved, but code collision detection and resolution complexity increases

Engineering Contradiction:

Improveparallel transmission efficiencyVSAvoidcollision management complexity

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The patent implements feedback mechanisms where the access point monitors transmissions from multiple AMP STAs using their assigned orthogonal codes. When a code collision is detected, the AP sends feedback to the involved STAs to reselect codes. This feedback loop enables efficient parallel transmission while managing collision resolution complexity through centralized monitoring and reactive code reassignment.

Inventive Principle:

Principle #23Feedback

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 allows multiple AMP stations to transmit in parallel to a Wi-Fi access point with minimal interference, ensuring secure and efficient communication by avoiding code collisions.

Implementation Method 1

transmitting an illumination signal to a first AMP STA and a second AMP STA

Methodology Applied

Scientific EffectElectromagnetic radiation:

Implementation Method 2

a system transmits energy that BKDs receive and use for their own transmissions. In one form, the BKD is entirely passive, and merely reflects (thus in real time) the energy

Methodology Applied

Scientific EffectBackscattering: Scattering

Data Source

PatentUS20250168887A1Adaptive code assignment to ambient power stations

Publication Date: 2025.05.22 CISCO TECHNOLOGY INC

AI summary

Embodiments herein describe using transmission codes for ambient power stations (AMP STAs) so multiple AMP STAs can transmit in parallel to a Wi-Fi access point (AP). In order for the AMP STAs to transmit in parallel, the STAs use different codes. In one embodiment, the AMP STAs can use random timers to determine when they transmit and select a code to use during transmission. Before the timer expires, the AMP STAs can listen to see whether other AMP STAs are using the same code (e.g., a collision), and if so, select a different code. However, some AMP STAs may not have the ability to detect a collision. In that case, the AP can determine collisions for the AMP STAs and instruct the AMP STAs to select different codes.