Abstract: A method for determining a symbol boundary in a data packet belonging to a received OFDM signal is provided. The data packet includes a first training filed and a second training field, which begins with a guard interval. The method includes detecting the beginning of the data packet, and starting an automatic gain control process. The method further includes, after the automatic gain control process is locked, determining autocorrelation peaks and estimating the symbol boundary from times of the autocorrelation peaks.

Abstract: In near field communication between an active initiator and a plurality of passive listening devices, the initiator device obtains a unique identity code from each listening device using an initialization process. The initiator transmits a poll request signal including a sequence of coupled data including an identification vector and an allocation vector. Each listening device stores an embedded introduction vector. In response to receive of the poll request signal, the listening device compares each received introduction vector with its stored embedded introduction vector. If a match is found, the listening device calculates a time slot for transmission of its poll response signal based on the coupled allocation vector with the matched introduction vector. The time slot calculated will not overlap with any other time slot so that bit level collisions in the poll response signals will be avoided.

Abstract: A near field communication (NFC) initiator communicates with a target device. The carrier is modulated to transmit a digital signal. During time slots allocated for target communication, the field is load modulated by the target. The target load modulator is driven by a digital modulator to vary voltage at antenna terminals so that peak amplitude of the carrier varies for specified periods between high and low values. To alleviate interference in the target device caused by the generation of aliases during transition, the load modulator sequentially applies a range of resistances to vary the amplitude (voltage) during transition according to a specific waveform determined by the infinite impulse response of a low pass filter tuned to the cut of frequency and sampling frequency determined according to the coexistence and cohabitation specifications of a chip in which the NFC functionality is embedded.

Abstract: A method of conditioning a first signal transmitted between a first and a second near field communication, NFC, device, the method comprising: determining a transfer function representative of a distortion arising from transfer of a signal from the first NFC device to the second NFC device; determining a pre-distortion function from the transfer function; and applying the pre-distortion function to the first signal, wherein the pre-distortion function at least partially compensates for the determined transfer function.

Abstract: A receiver is configured to determine an estimation of a Sampling Frequency Offset an OFDM signal received from an emitter over a transmission channel. The received OFDM signal is constituted of symbols. The receiver receives symbols from the emitter through a first path of said transmission channel, and receives the symbols from the emitter through a second path of the transmission channel. On the second path, the symbols are characterized by a different ratio between a first duration of a total OFDM symbol and a second duration of useful data portion of the OFDM symbol, than on the first path. The receiver determines the estimation according to received symbols through the first and second paths.

Abstract: It is proposed a method for receiving and demodulating an orthogonal frequency division multiplexing signal received through a transmission channel (TC) by a receiver (RCV), comprising demultiplexing said signal to generate time symbols (yl(n)) and performing a time-to-frequency conversion of these time symbols to generate frequency bins (Yl(k)) corresponding to received symbols, the received symbols comprising preamble symbols. The method comprises: Determining an estimated carrier frequency offset on the basis of frequency bins corresponding to used subcarriers of the preamble symbols; Applying said estimated carrier frequency offset to the time symbols so as to correct the carrier frequency of these received symbols.

Abstract: A method for managing the operation of an object capable of contactless communication with a reader magnetically coupled to the object includes a phase for transmission of information from the object to the reader and includes a modulation of the impedance of a load connected across the terminals of the antenna of the object. Prior to the transmission phase, a monitoring phase includes a monitoring of the level of amplitude modulation of a modulated test signal present at the antenna of the object and resulting from a test modulation of the impedance of the load and a capacitive modification of the impedance of the load if this level is lower than a threshold.

Abstract: A system can be used for contactless communication of information between a first device and a second device, each having an antenna intended to be coupled via a near magnetic field. The first device includes a transmit chain having first circuitry configured to generate a digital data stream corresponding to the information to be transmitted, and second circuitry configured to generate a first amplitude-modulated and dithered signal in the antenna of the first device from this stream and from an application of a first dithering. The second device includes a receive chain having third circuitry configured to carry out a frequency transposition of a second amplitude-modulated and dithered signal originating from the first signal, with application of a second dithering synchronous with the first dithering.

Abstract: A receiver estimates a vector of emitted symbols over a MIMO transmission channel which is emitted by emitting antennas. The receiver receives a vector of received symbols on receiving antennas. Estimation of the vector of emitted symbols is made by calculating a metric associated with a criterion for each vector of a subset of all possible vectors of emitted symbols and selecting an estimation for said vector of emitted symbols as the vector of emitted symbols among said subset which minimizes said metric.

Abstract: A method and an apparatus determine a time of start of series of OFDM symbols forming an OFDM packet, wherein one or more symbols of the OFDM signal includes a plurality of copies of a short training sequence made of a plurality of time-domain samples. The method includes determining a coarse time index, determining a fine time index, and determining the time of start of each OFDM symbols based on the fine time index. The coarse time-domain sample of the coarse time index is within a coarse estimation error interval, and the time-domain samples of the coarse estimation error interval are converted into frequency domain samples. A metric value is determined for each frequency domain samples, and the fine time index is the time index corresponding to one of the coarse estimation error interval having its associated frequency domain sample having the lowest metric value.

Abstract: This invention deals with a method of communication comprising, at transmitting side, encoding, with one or more space time block codes chosen among a predetermined group of space time block codes (M1, M2, M3, M4), one or more series of several consecutive symbols in a header of a packet of data of a same data format (11 to 44), said space time block code or said succession of space time block codes being chosen so as to be representative of said data format (11 to 44).

Abstract: A receiver estimates a vector of emitted symbols over a MIMO transmission channel which are emitted by a emitting antennas. The receiver receives a vector of received symbols on receiving antennas. Estimation of the vector of emitted symbols is made by calculating a metric associated with a criterion for each vector of a subset of all possible vectors of emitted symbols and selecting an estimation for said vector of emitted symbol as the vector of emitted symbols among said subset which minimizes said metric.

Abstract: An interference cancellation technique is implemented in a receiver adapted for determining an estimation of interferences when receiving an OFDM signal made of packets. Each packet includes a first training field, a second training field, a first header field, a second header field and a data field. The receiver detects a first symbol value of the first header field, and a second symbol value of the second header field, the first and the second header fields having been modulated using different modulation schemes. The estimation of interferences is determined using the first and the second symbol values.

Abstract: It is proposed a method for receiving and demodulating an orthogonal frequency division multiplexing signal received through a transmission channel (TC) by a receiver (RCV), comprising demultiplexing said signal to generate time symbols (yl(n)) and performing a time-to-frequency conversion of these time symbols to generate frequency bins (Yl(k)) corresponding to received symbols, the received symbols comprising preamble symbols. The method comprises: Determining an estimated carrier frequency offset on the basis of frequency bins corresponding to used subcarriers of the preamble symbols; Applying said estimated carrier frequency offset to the time symbols so as to correct the carrier frequency of these received symbols.

Abstract: The invention concerns a Near Field Communication method of detection of a tag presence by a tag reader, comprising: stimulating (S2) the transmitter of the reader so as to generate an impulse response of said transmitter, evaluating (S3) the generated impulse response of said transmitter, assessing (S4), from the evaluated impulse response of said transmitter, the presence (S5) or the absence (S6) of a tag.

Abstract: A method of conditioning a first signal transmitted between a first and a second near field communication, NFC, device, the method comprising: determining a transfer function representative of a distortion arising from transfer of a signal from the first NFC device to the second NFC device; determining a pre-distortion function from the transfer function; and applying the pre-distortion function to the first signal, wherein the pre-distortion function at least partially compensates for the determined transfer function.

Abstract: A method of self-test for a near-field communication (NFC) radio frequency (RF) front-end unit comprising one antenna driver and at least one unit from a group comprising one reader and one card emulator, the RF front-end unit being connected to a digital front-end unit, wherein the antenna driver and the unit are interconnected through a first connection line via their respective first input-output interface and are also interconnected through a second connection line via their respective second input-output interface, the digital front-end unit being connected to the second connection line, the method comprising: activating the antenna driver and the unit based on control signals; generating a first signal onto the first connection line by modulating a respective first bitstream; retrieving a second bitstream from the second connection line, by demodulating the first signal; and, determining an outcome of the self-test by monitoring the demodulated signal.

Abstract: Receiver (RCV) adapted for compensating for Symbol Timing Offset when receiving OFDM symbols, over a communication channel (TC), comprising: means (REG, DFT, CMP) for detecting a first phase with no Inter-Symbol Interference, means (REG, DFT, CMP) for detecting a second phase with presence of Inter-Symbol Interference, means (REG, DFT, CMP) for compensating for said Symbol Timing Offset by estimating starting points of said received OFDM symbols as being one sample before the start of said second phase. The timing synchronization is achieved in frequency domain by monitoring amplitude variation of the demodulated subcarriers symbols, said variation being due to the presence of Inter Symbol Interference when the FFT window overlaps with the subsequent OFDM symbol.

Abstract: A method of determining a calibration of a near field communication, NFC, device, the NFC device comprising a receiver circuit, a transmitter circuit and a load modulator circuit, the method comprising: generating a carrier signal in the transmitter circuit, generating a modulation signal in the load modulator circuit, generating a modulated carrier signal, comprising first and second frequencies, by applying the modulation signal to the carrier signal, applying the modulated carrier signal at an input of the receiver circuit, and determining a response parameter of the receiver circuit on the basis of the response of the receiver circuit to the first and second frequencies in the modulated carrier signal.

Abstract: A transceiver for orthogonal frequency division multiplex communication has a transmitter module (1) and a receiver module (2). The transmitter (1) has an l-path (3) and a Q-path (4) to receive signals on a number of subcarriers provided by a signal generator (9). The receiver module (2) has a receiver l-path (7) and a receiver Q-path (8) to deliver signals to a processor (15). IQ imbalance is calculated for each of the transmitter and receiver by the signal generator sending a sample signal (Xl(k), XQ(k)) over a one of the transmitter paths. The signal is then applied to one or each of the inputs to the receiver paths (7,8) to generate receiver output signals Yl(k), YQ(k), RQ(k). The processor (15) is responsive to the output signals to calculate the transmitter and receiver IQ imbalance for that subcarrier. A calibrator (19) and compensator (20) are responsive to the calculated IQ imbalance to correct or compensate each subcarrier of the transceiver band.