In accordance with a first aspect of the present disclosure, a channel equalizer is provided for use in a near field communication (NFC) device, the channel equalizer comprising: a filter configured to receive an input signal and to generate a filtered output signal; an estimator configured to determine filter coefficients to be used by said filter; a synchronizer configured to determine when to enable the channel equalizer and to provide one or more corresponding control signals to the estimator. In accordance with a second aspect of the present disclosure, a corresponding method of operating a channel equalizer for use in a near field communication (NFC) device is conceived.

A blind channel equalizer device for a radiofrequency receiver suitable for modulating the constant envelope signal of the transmission includes: an adjustable linear digital filter, defined at a point in time by the coefficients) thereof, able to filter an input signal in order to produce an output signal; an estimator able to estimate a power of the input signal; an adapter able to adapt the filter by calculating the coefficients of the filter at a point in time by subtracting, from the filter coefficients at a preceding point in time, the gradient of a cost function assigned with a correction coefficient. The cost function includes a first distance criterion between the square of the output signal and the power, wherein the correction coefficient is a product including a constant convergence coefficient and a scaling coefficient inversely proportional to the square of the power. Also disclosed is a related Radiofrequency receiver.

A method for emulating a communication system with fast changing link condition, applied to a testbed system including an interference emulator, a transmitter, and a receiver, includes: by the transmitter, generating code-word symbols, in an initial symbol sequence, according to information bits; evaluating an interference condition and a time duration for each code-word symbol; reordering the code-word symbols to a reordered symbol sequence based on interference conditions; evaluating a total time duration of code-word symbols under each interference condition; and transmitting the code-word symbols in the reordered symbol sequence. The method also includes: by the interference emulator, obtaining the total time duration of code-word symbols under each interference condition from the transmitter; and providing an emulated interference environment by ordering the time durations of different interference conditions. The start time for transmitting code-word symbols with an interference condition is synchronized with the start time for emulating the interference condition.

A method for emulating a communication system with fast changing link condition, applied to a testbed system including an interference emulator, a transmitter, and a receiver, includes: by the transmitter, generating code-word symbols, in an initial symbol sequence, according to information bits; evaluating an interference condition and a time duration for each code-word symbol; reordering the code-word symbols to a reordered symbol sequence based on interference conditions; evaluating a total time duration of code-word symbols under each interference condition; and transmitting the code-word symbols in the reordered symbol sequence. The method also includes: by the interference emulator, obtaining the total time duration of code-word symbols under each interference condition from the transmitter; and providing an emulated interference environment by ordering the time durations of different interference conditions. The start time for transmitting code-word symbols with an interference condition is synchronized with the start time for emulating the interference condition.

In accordance with a first aspect of the present disclosure, a channel equalizer is provided for use in a near field communication (NFC) device, the channel equalizer comprising: a filter configured to receive an input signal and to generate a filtered output signal; an estimator configured to determine filter coefficients to be used by said filter; a synchronizer configured to determine when to enable the channel equalizer and to provide one or more corresponding control signals to the estimator. In accordance with a second aspect of the present disclosure, a corresponding method of operating a channel equalizer for use in a near field communication (NFC) device is conceived.

The present disclosure provides a multi-carrier time-division multiplexing (MC-TDMA) modulation and demodulation method and system. Before multi-carrier modulation is performed on an input symbol, an interleaving allocation and an FFT may be performed, a time domain symbol may be transformed into a frequency domain symbol signal to perform a MDFT treatment. A sending end may adopt an analyzing filter bank structure, and pre-filtering and an IFFT may be performed on a signal successively. A pre-filter may be positioned between an NM point FFT and an M point IFFT, a PAPR value of the system may be reduced using the symmetry of a coefficient of a filter, and a frequency domain symbol signal may be allocated to different sub-bands for multi-carrier modulation.

The present disclosure provides a multi-carrier time-division multiplexing (MC-TDMA) modulation and demodulation method and system. Before multi-carrier modulation is performed on an input symbol, an interleaving allocation and an FFT may be performed, a time domain symbol may be transformed into a frequency domain symbol signal to perform a MDFT treatment. A sending end may adopt an analyzing filter bank structure, and pre-filtering and an IFFT may be performed on a signal successively. A pre-filter may be positioned between an NM point FFT and an M point IFFT, a PAPR value of the system may be reduced using the symmetry of a coefficient of a filter, and a frequency domain symbol signal may be allocated to different sub-bands for multi-carrier modulation.

The present disclosure provides a multi-carrier time-division multiplexing (MC-TDMA) modulation and demodulation method and system. Before multi-carrier modulation is performed on an input symbol, an interleaving allocation and an FFT may be performed, a time domain symbol may be transformed into a frequency domain symbol signal to perform a MDFT treatment. A sending end may adopt an analyzing filter bank structure, and pre-filtering and an IFFT may be performed on a signal successively. A pre-filter may be positioned between an NM point FFT and an M point IFFT, a PAPR value of the system may be reduced using the symmetry of a coefficient of a filter, and a frequency domain symbol signal may be allocated to different sub-bands for multi-carrier modulation.

A low voltage drive circuit includes a transmit analog to digital circuit that converts transmit digital data into analog outbound data by: generating a DC component; and generating an oscillating component at a first frequency that conveys the transmit digital data, wherein the magnitudes of both the oscillating component and the DC component are limited to a range that is less than a difference between the magnitudes of the power supply rails of the circuit, and wherein the oscillating component and the DC component are combined to produce the analog outbound data. A drive sense circuit drives an analog transmit signal onto a bus, wherein the analog outbound data is represented within the analog transmit signal as variances in loading of the bus at a first frequency and wherein analog inbound data is represented within an analog receive signal as variances in loading of the bus at a second frequency.

A low voltage drive circuit includes a transmit analog to digital circuit that converts transmit digital data into analog outbound data by: generating a DC component; and generating an oscillating component at a first frequency that conveys the transmit digital data, wherein the magnitudes of both the oscillating component and the DC component are limited to a range that is less than a difference between the magnitudes of the power supply rails of the circuit, and wherein the oscillating component and the DC component are combined to produce the analog outbound data. A drive sense circuit drives an analog transmit signal onto a bus, wherein the analog outbound data is represented within the analog transmit signal as variances in loading of the bus at a first frequency and wherein analog inbound data is represented within an analog receive signal as variances in loading of the bus at a second frequency.