Multiple Subcarriers Modulator, Backscatter Device and Hub Device in a Backscatter Communication System

A multiple subcarriers modulator for a backscatter device comprised in a backscatter communication system, the multiple subcarriers modulator comprising:

• an antenna switch;
• an impedance matrix comprising a plurality of impedances;
• a first modulator configured to generate a first modulated signal by modulating a first data stream with a first subcarrier having a first frequency;
• a second modulator configured to generate a second modulated signal by modulating a second data stream with a second subcarrier having a second frequency;
• a summing circuit configured to generate a control signal by combining the first and second modulated signals;
• and
• a switch controller configured to control the antenna switch such that one of the impedances in the impedance matrix is connected to an antenna based on the control signal.

A backscatter device, comprising:

• a multiple subcarriers modulator, the multiple subcarriers modulator comprising:
• an antenna switch;
• an impedance matrix comprising a plurality of impedances;
• a first modulator configured to generate a first modulated signal by modulating a first data stream with a first subcarrier having a first frequency;
• a second modulator configured to generate a second modulated signal by modulating a second data stream with a second subcarrier having a second frequency;
• a summing circuit configured to generate a control signal by combining the first and second modulated signals;
• and
• a switch controller configured to control the antenna switch such that one of the impedances in the impedance matrix is connected to an antenna based on the control signal.

A hub device comprised in a backscatter communication system, the hub device comprising:

• an antenna;
• a power amplifier for generating a carrier frequency signal with a carrier frequency for radiating by the antenna;
• a power splitter for splitting the carrier frequency signal;
• and
• a receiver, wherein the receiver comprises:
• a band-pass filter configured to filter a backscattered signal received from a backscatter device and generate a filtered signal, wherein the backscattered signal comprises a first and a second data streams modulated on a first and second subcarriers respectively;
• an amplifier configured to amplify the filtered signal and generate an amplified signal;
• a mixer configured to down-convert the amplified signal to a baseband signal by mixing the amplified signal with a signal generated from the power splitter;
• a low-pass filter configured to filter the baseband signal and generate a filtered baseband signal;
• two-comparators configured to extract bit streams from the filtered baseband signal;
• and
• a baseband processor comprising a look-up table to extract the first dada stream and the second data stream from the bit streams.

A backscatter communication system, comprising:

• a hub device of claim;
• and
• a backscatter device;
• wherein the hub device comprises:
• an antenna;
• a power amplifier for generating a carrier frequency signal with a carrier frequency for radiating by the antenna;
• a power splitter for splitting the carrier frequency signal;
• and
• a receiver, wherein the receiver comprises:
• a band-pass filter configured to filter a backscattered signal received from a backscatter device and generate a filtered signal, wherein the backscattered signal comprises a first and a second data streams modulated on a first and second subcarriers respectively;
• an amplifier configured to amplify the filtered signal and generate an amplified signal;
• a mixer configured to down-convert the amplified signal to a baseband signal by mixing the amplified signal with a signal generated from the power splitter;
• a low-pass filter configured to filter the baseband signal and generate a filtered baseband signal;
• two-comparators configured to extract bit streams from the filtered baseband signal;
• and
• a baseband processor comprising a look-up table to extract the first dada stream and the second data stream from the bit streams;
• wherein the backscatter device comprises a multiple subcarriers modulator, the multiple subcarriers modulator comprising: