Multi-Subcarrier Backscatter Waveform for Selective Fading
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Solution Overview
Problem
Existing backscatter communication techniques, such as those used in RFID systems, are limited to single subchannels and are affected by selective fading, which decreases communication efficiency, and are not compatible with advanced wireless systems like New Radio (NR).
Innovation Solution
Implementing a multiple-subcarrier waveform for backscatter communications, where a user equipment (UE) activates and communicates with zero-power devices using a continuous wave transmission modulated with amplitude shift keying (ASK) over multiple subcarriers, with parameters determined by subcarrier spacing (SCS), enabling compatibility with NR systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If single subchannel backscatter communication is used, then device simplicity is maintained, but communication efficiency deteriorates due to selective fading
Solution Approach 1:
The patent divides the single subchannel into multiple subcarriers (e.g., subcarriers 0-15 in a 180 kHz bandwidth). Each subcarrier experiences different fading conditions, and by spreading the backscatter signal across multiple subcarriers, the system achieves frequency diversity to combat selective fading. The reader transmits pilot signals on each subcarrier and the tag reflects signals selectively, enabling efficient communication without requiring complex device architecture.
2Adaptability or versatility
If traditional backscatter techniques are used, then compatibility with legacy systems is maintained, but adaptability to advanced wireless systems deteriorates
Solution Approach 1:
The patent enables backscatter tags to operate in both traditional RFID systems and advanced 5G/NR systems using the same hardware architecture. The tag can function as a reflective device in legacy systems while also supporting multi-subcarrier waveforms in 5G NR systems. The reader performs dual roles by supporting both traditional single-subchannel communication and advanced multi-subcarrier communication with features like pilot signal transmission and selective reflection control, achieving multi-functionality without requiring separate dedicated systems.
3Reliability
If continuous wave transmission over multiple subcarriers is used, then communication reliability is improved, but energy consumption increases
Solution Approach 1:
The backscatter tag harvests energy from the reader's transmitted signals to power its own operations including signal processing and selective reflection. The tag does not require an independent power source; instead, it uses the incident electromagnetic waves from the reader's continuous wave transmission to generate the power needed for communication. This energy harvesting approach enables reliable multi-subcarrier communication while avoiding additional energy consumption from active transmission at the tag side.
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
Enhances communication efficiency and reliability by allowing backscatter devices to operate in multiple-subcarrier waveforms, improving throughput and compatibility with advanced wireless systems.
Implementation Method 1
at least a portion of the continuous wave transmission is modulated in accordance with an ASK modulation scheme and includes a set of commands
Data Source
AI summary
Methods, systems, and devices for wireless communications are described. In some systems, a network entity may determine a subcarrier spacing (SCS) for multiple subcarriers in a continuous wave transmission. The network entity may transmit a control message indicating one or more parameters based on the SCS for the continuous wave transmission. A user equipment (UE) may select one or more parameters of the continuous wave transmission associated with multiple subcarriers. The UE may transmit the continuous wave transmission for activating and communicating with a zero power device. The continuous wave transmission may be modulated with an amplitude shift keying (ASK) modulation scheme and include a set of commands. The zero power device may send signaling in response to the received continuous wave transmission and the set of commands back to the UE.