A transmitter of an FBMC-MIMO system in which, for each FBMC-OQAM modulator associated with a transmission antenna, the symbols of a block to be transmitted are grouped in pairs, the input symbols in a pair being combined to output first and second combined symbols, the combined symbols being input to the FBMC-OQAM modulator. The invention also relates to a receiver including an FBMC-OQAM demodulator and an ML detector from the observables obtained, for each reception antenna. The used ML detection allows for not being affected by intrinsic interference and obtaining a high degree of diversity without increasing the number of antennas.

Transmitting apparatus and receiving apparatus for communication systems using coded orthogonal frequency-division multiplexed (COFDM) dual-subcarrier modulation (DCM) signals. The same coded data is mapped both to COFDM subcarriers located in the lower-frequency half spectrum of the DCM signal and to COFDM subcarriers located in its upper-frequency half spectrum. The mapping of COFDM subcarriers in those half spectra employ labeling diversity preferred for reception of DCM with less error when accompanied by interfering additive white Gaussian noise (AWGN). In preferred forms of COFDM DCM signal, the quadrature amplitude modulation (QAM) of COFDM subcarriers is Gray mapped to position palindromic lattice-point labels along one of the diagonals of each square QAM constellation.

A method includes for a designated pilot symbol of at least one pilot symbol to be inserted into a data sequence, determining a first subcarrier and a second subcarrier adjacent to a position of the designated pilot symbol in a frequency domain; at least separately determining a first position and a second position on the first subcarrier and the second subcarrier; determining a first symbol and a second symbol, so that the first symbol is capable of neutralizing interference on the designated pilot symbol of data symbols in positions other than the first position within a predetermined range of the first subcarrier, and the second symbol is capable of neutralizing interference on the designated pilot symbol of data symbols in positions other than the second position within a predetermined range of the second subcarrier; and respectively inserting the first symbol and the second symbol in the first and second positions.

Disclosed herein is a station (STA) device of a wireless LAN (WLAN) system. The STA device includes a radio frequency (RF) unit sending and receiving a radio signal and a processor controlling the RF unit. The processor may generate a physical protocol data unit (PPDU) including a physical preamble and a data field and send the PPDU using the RF unit.

A backscatter modulator for providing low power wireless communications. The disclosed modulator provides phase control for discriminating backscatter from the antenna versus other objects. In addition, the disclosed backscatter modulator provides amplitude modulation so that the technique can provide a non-constant envelope which can provide an intentional imbalance to manipulate super-position to provide envelope control of the reflected signal, while still maintaining the frequency translation properties. The disclosed backscatter modulator thus allows compatibility with QAM, OFDM and other non-constant envelope modulation schemes to be backscattered, while still supporting the frequency translation behavior.

An apparatus and method for filter bank multi-carrier signal modulation with a low peak-to-average power ratio (PAPR) in a multiple antenna system are disclosed. According to embodiments of the present disclosure, in a multiple antenna transmission method, after a plurality of transmission candidate signals, which are modulated for each antenna using discrete Fourier transform (DFT) spread filter bank multi-carrier and offset quadrature amplitude modulation (FBMC/OQAM) techniques and are capable of obtaining a single carrier effect, are generated, a transmission candidate signal with a low PAPR can be selected and transmitted, and thus peak-to-average power ratio performance can be effectively improved, and interference between subcarriers can be eliminated by applying an Alamouti coding manner.

An OFDM transmitter and an OFDM receiver respectively transmit and receive N (N?2, N is an integer) control symbols. For each control symbol, a guard interval time-domain signal is, for example, identical to a signal obtained by frequency-shifting at least a portion of a useful symbol time-domain signal by an amount different from any other symbol, or to a signal obtained by frequency-shifting one or both of a portion and a span of a useful symbol interval time-domain signal different from any other symbol by a predetermined amount.

A method for transmitting a multi-carrier signal implementing an OQAM-type modulation, formed of a temporal succession of symbols including data elements modulating a carrier frequency of the signal. A carrier frequency modulated by one of the data elements is called a carrier, wherein a set of carriers is allocated to a transmitter unit. The method includes inserting a sequence of pilots specific to the transmitter unit at a given time into the multi-carrier signal on the allocated set of carriers. The sequence of pilots includes: a sequence of non-zero complex values, inserted on odd or even carriers, alternating with zero values, inserted on the other carriers, respectively even or odd-numbered; non-zero complex values of the sequence of pilots, their frequency transforms and inverse frequency transforms being with a constant envelope; and and a sequence of zero values modulating the carriers of the set of carriers allocated at the following time.

An OFDM transmitter and an OFDM receiver respectively transmit and receive N (N?2, N is an integer) control symbols. For each control symbol, a guard interval time-domain signal is, for example, identical to a signal obtained by frequency-shifting at least a portion of a useful symbol time-domain signal by an amount different from any other symbol, or to a signal obtained by frequency-shifting one or both of a portion and a span of a useful symbol interval time-domain signal different from any other symbol by a predetermined amount.

A modulation scheme conversion device includes: a backscattering tag to which a tag signal is provided; and a tag signal forming unit for forming a tag signal. The modulation scheme conversion device multiplies a radio signal, which has been modulated in a first modulation scheme, and a tag signal, and reconfigures the multiplied signal by using a second modulation scheme, so as to backscatter the reconfigured signal, wherein the reconfiguration is performed in a physical (PHY) layer.