Frequency Translating Backscatter Modulator with Amplitude Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing backscatter modulators lack amplitude control, limiting their applicability to standards requiring non-constant envelopes, such as 802.11a, g, n, ac, and ax, due to interference from unmodulated reflections known as 'in-band blockers'.
Innovation Solution
A frequency translating backscatter modulator with amplitude control, utilizing multiple parallel switches and amplitude control circuits to modulate both amplitude and phase, enabling non-constant envelope modulation schemes like QAM and OFDM by controlling the antenna termination impedance through internal carrier phases.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If frequency translation technique is used to avoid in-band blockers, then spectral separation between modulated and unmodulated reflections is achieved, but compatibility with standards requiring non-constant envelopes (QAM/OFDM) is lost
Solution Approach 1:
The patent applies dynamics by making the backscatter modulator adaptable to both constant envelope (BPSK/QPSK) and non-constant envelope (QAM/OFDM) modulation schemes. The system dynamically adjusts its operation mode based on the communication protocol requirements, enabling spectral separation when needed while maintaining compatibility with modern WiFi standards that require amplitude control.
Solution Approach 2:
The patent changes the modulation parameters to support both constant and non-constant envelope schemes. By adjusting the modulation depth and amplitude control parameters, the system can operate in spectral separation mode for constant envelope modulations while transitioning to amplitude-controlled mode for QAM/OFDM, thus resolving the compatibility issue.
2Adaptability or versatility
If amplitude control is added to support non-constant envelope modulation, then compatibility with QAM/OFDM standards is improved, but device complexity increases
Solution Approach 1:
The patent implements a universal backscatter modulator that can perform both constant envelope and non-constant envelope modulation schemes using the same hardware structure. The single device supports multiple modulation types (BPSK, QPSK, QAM, OFDM) by configuring different operational modes, thereby achieving multi-functionality without requiring separate dedicated circuits for each modulation type.
Solution Approach 2:
The system uses dynamic configuration to enable amplitude control only when needed for non-constant envelope modulations. The modulator can switch between simple phase modulation for constant envelope schemes and more complex amplitude-controlled modulation for QAM/OFDM, optimizing the balance between functionality and complexity based on the operational requirements.
3Device complexity
If simple phase modulation is used, then device complexity is reduced, but applicability to standards requiring amplitude control is limited
Solution Approach 1:
The patent enables parameter changes by allowing the modulator to adjust its modulation characteristics based on the required protocol. For simple phase modulation, the system uses basic phase shifting with minimal circuitry. When amplitude control is needed for QAM/OFDM, the system activates amplitude control circuits and adjusts the modulation parameters accordingly, thus adapting to different protocol requirements without permanent complexity increase.
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 solution allows for wider compatibility with various WiFi standards and wireless communication protocols, effectively reducing interference from unmodulated reflections and enhancing communication reliability across different data rates.
Implementation Method 1
a frequency divider for dividing an incoming frequency and generating quadrature internal carrier phases
Implementation Method 2
multiple amplitude control circuits for controlling an amplitude output of multiple switches in parallel connected to an antenna by controlling an antenna termination impedance
Implementation Method 3
backscatter modulator device with an internal carrier offset from the illuminating signal frequency for frequency translating and modulating a reflected signal from an antenna
Data Source
AI summary
A backscatter modulator for providing low power wireless communications. The disclosed modulator provides phase control for discriminating backscatter from the antenna versus other objects. In addition, the disclosed backscatter modulator provides amplitude modulation so that the technique can provide a non-constant envelope which can provide an intentional imbalance to manipulate super-position to provide envelope control of the reflected signal, while still maintaining the frequency translation properties. The disclosed backscatter modulator thus allows compatibility with QAM, OFDM and other non-constant envelope modulation schemes to be backscattered, while still supporting the frequency translation behavior.