Backscatter Receiver Harmonic Removal via Baseband Phase Rotation
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Solution Overview
Problem
Existing harmonic removal methods in wireless communication systems incur an increased amount of calculation due to higher sampling rates for signals with frequencies higher than the baseband, leading to potential increases in circuit size and processing time.
Innovation Solution
A wireless communication system that includes a transmitter, passive terminals, and a receiver, where the passive terminals superimpose predetermined subcarriers on a carrier wave, and the receiver performs frequency conversion, orthogonal transformation, and harmonic-order rotation to estimate a carrier phase angle, allowing for the subtraction of interference components from the subcarrier data series.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a signal with frequency higher than baseband is sampled for harmonic removal, then harmonic components can be removed from the received signal, but the sampling rate increases leading to increased calculation amount
Solution Approach 1:
The patent changes the frequency parameter of the signal by down-converting the received signal from a higher frequency band to baseband before performing harmonic removal. This parameter transformation allows the same harmonic removal functionality to operate at a lower sampling rate, thereby reducing the calculation amount while maintaining effectiveness
Solution Approach 2:
The patent introduces an intermediary frequency conversion step (down-conversion to baseband) between signal reception and harmonic removal processing. This intermediary transformation enables the subsequent harmonic removal operations to be performed more efficiently at baseband frequencies rather than at the original higher sampling rate
Data Source
AI summary
A wireless communication system includes: a transmitter configured to transmit a carrier wave that is unmodulated; a plurality of passive terminals; and a receiver. Each of the plurality of passive terminals is configured to receive the carrier wave, superimpose a subcarrier of which frequency is determined in advance for each of the plurality of passive terminals on a backscatter of the carrier wave, modulate a signal generated by a signal source onto the subcarrier using a predetermined modulation scheme, and transmit the backscatter. The receiver is configured to receive multiple backscatters transmitted from the plurality of passive terminals, perform frequency conversion and orthogonal transformation on the multiple backscatters to generate a finite-length data series having an I component and a Q component, remove an interference component from the finite-length data series, and perform demodulation to acquire the signal of the signal source in each of the plurality of passive terminals.