Resonating backscatter radio system with pulse position modulation

A method performed in a transponder for receiving power from a transceiver module and for transferring information between the transponder and transceiver module in a backscatter radio system, the transponder comprising a resonance circuit coupled to an antenna by a first switch, a rectifier circuit coupled to the antenna by a second switch and to the resonance circuit by a third switch, the method comprising:

• receiving, at the antenna, a radio frequency pulse signal transmitted in a forward link from the transceiver module to the transponder during a first symbol period, the radio frequency pulse signal being modulated with Pulse Position Modulation, PPM, and comprising a power and information transferring pulse and a time reference pulse within a dual symbol duration comprising the first symbol period and a second symbol period, and the information being coded by the position of the power and information transferring pulse with respect to the time reference pulse;
• converting the received power and information transferring pulse to power in the rectifier circuit by switching on the second switch during the power transferring and information pulse slot;
• generating a resonance signal in the resonance circuit, in response to the received time reference pulse by switching on the first switch during the time reference pulse slot, the resonance circuit being configured to have a resonant frequency at a carrier frequency of the received time reference pulse and the resonance signal is generated at the carrier frequency of the received time reference pulse;
• generating a response radio frequency pulse signal with PPM by switching on the first switch during a designated PPM time slot within the second symbol period, the designated PPM time slot being configured with a time offset such that the first and second symbol periods are separated in time domain;
• transmitting the generated response radio frequency pulse signal in a reverse link from the transponder to the transceiver module during the second symbol period;
• and
• resetting the resonance circuit by switching on the third switch each time after the response radio frequency pulse signal has been transmitted.

A backscatter radio system for transferring power and information, the backscatter radio system comprising a transceiver module and a transponder, the backscatter radio system being configured to:

• generate by the transceiver module, a radio frequency pulse signal with Pulse Position Modulation, PPM, the generated radio frequency pulse signal comprising a power transferring pulse and a time reference pulse within a dual symbol duration comprising a first symbol period and a second symbol period, and the information being coded by the position of the power and information transferring pulse with respect to the time reference pulse;
• transmit the radio frequency pulse signal in a forward link from the transceiver module to the transponder during the first symbol period, the power and information transferring pulse enabling a power injection to a rectifier circuit comprised in the transponder and the time reference pulse enables an excitation of a resonance signal in a resonance circuit comprised in the transponder;
• receive at the transponder, the radio frequency pulse signal from the transceiver module;
• convert at the transponder, the received power and information transferring pulse to power;
• generate a resonance signal at a carrier frequency of the received time reference pulse in the resonance circuit comprised in the transponder, in response to the received time reference pulse;
• generate by the transponder, a response radio frequency pulse signal with PPM during the second symbol period;
• and
• transmit the response radio frequency pulse signal with PPM in a reverse link from the transponder to the transceiver module during the second symbol period, the response radio frequency pulse signal with PPM being generated using the resonance signal generated in the resonance circuit comprised in the transponder with a time offset such that the first and second symbol periods are separated in time domain.

A method performed in a backscatter radio system for transferring power and information, the backscatter radio system comprising a transceiver module and a transponder, the method comprising:

• generating by the transceiver module, a radio frequency pulse signal with Pulse Position Modulation, PPM, the generated radio frequency pulse signal comprising a power and information transferring pulse and a time reference pulse within a dual symbol duration comprising a first symbol period and a second symbol period, and the information being coded by the position of the power and information transferring pulse with respect to the time reference pulse;
• transmitting the radio frequency pulse signal in a forward link from the transceiver module to the transponder during the first symbol period, the power and information transferring pulse enabling a power injection to a rectifier circuit comprised in the transponder and the time reference pulse enables an excitation of a resonance signal in a resonance circuit comprised in the transponder;
• receiving at the transponder, the radio frequency pulse signal from the transceiver module;
• converting at the transponder, the received power and information transferring pulse to power;
• generating in the resonance circuit comprised in the transponder, a resonance signal at a carrier frequency of the received time reference pulse in response to the received time reference pulse;
• generating by the transponder, a response radio frequency pulse signal with PPM during the second symbol period;
• transmitting the response radio frequency pulse signal with PPM in a reverse link from the transponder to the transceiver module during the second symbol period;
• and
• the response radio frequency pulse signal with PPM being generated using the resonance signal generated in the resonance circuit comprised in the transponder with a time offset such that the first and second symbol periods are separated in time domain.