Disclosed is a method for the detection of more than one signals contained in a receive signal, the method comprising: down-converting the receive signal, thereby providing a down-converted signal in a complex IQ base band; at least partially cancelling the strongest user in the down-converted signal, thereby allowing for the detection of a possible secondary user.

Conventional filter bank multi-carrier (FBMC) wireless communication systems offer superior spectral properties compared to the cyclic-prefix orthogonal frequency-division multiplexing (CP-OFDM) approach, at the cost of an inherent shortcoming in dispersive channels called intrinsic imaginary interference. In this disclosure the DP-FBMC system was disclosed. A DP-FBMC based communication system uses two orthogonal polarizations for wireless communication systems: dual-polarization FBMC (DP-FBMC). The system significantly suppresses FBMC intrinsic interference. For the disclosed DP-FBMC all the multicarrier techniques used in CP-OFDM systems for channel equalization etc., are applicable without using complex processing methods that are required for conventional FBMC. Disclosed DP-FBMC also is more robust in multipath fading channels, and also to receiver carrier frequency offset (CFO) and Timing offset (TO). In the disclosed DP-FBMC system, three different structures may be used based on different multiplexing techniques.

An apparatus and a method. The apparatus includes an interference mitigation processor, including an input, an output, and configured to sum n msec received correlators over m msec, and analyze the n msec correlators to reduce interference. The method includes summing, by an interference mitigation processor, n msec received correlators over m msec; and analyzing, by an interference mitigation processor, the n msec correlators to reduce interference.

A discrete Fourier transform spread orthogonal time frequency space modulation method comprises the steps of performing DFT preceding processing and delay-Doppler domain mapping processing on the transmit data symbols, OTFS modulator, and performing delay-Doppler domain demapping processing and IDFT decoding processing on a received signal to realize demodulation; compared with the existing waveforms, including OFDM and DFT-s-OFDM, the proposed DFT-s-OTFS can reduce the bit error rate under high Doppler spread and the peak-to-average power ratio of the transmitted signal at the same time.

Embodiments of this application provide a side information transmission method and apparatus. Data to be transmitted by a transmit end includes at least one first data sub-block and at least one second data sub-block. A first modulated signal is obtained based on a first phase rotation factor. A second modulated signal is obtained based on a second phase rotation factor. Side information is generated based on the first phase rotation factor and the second phase rotation factor. The first data sub-block is carried on a first subcarrier, and the side information is also mapped to the first carrier. The first modulated signal corresponding to the at least one first data sub-block, the second modulated signal corresponding to the at least one second data sub-block, and a modulated signal corresponding to the side information are superposed to obtain a to-be-transmitted signal.

An embodiment of a receiver includes a first number of antennas and a signal analyzer. The antennas are each spaced from another of the antennas by approximately a distance, and are configured to provide, at one or more wavelengths that are greater than twice the distance, a channel capacity that exceeds a saturation channel capacity. The signal analyzer is configured to recover information from a second number of signals each received by at least one of the antennas over a respective one of a third number of signal pipes, and each having a wavelength that is greater than twice the distance, the second number being related to the third number. Such a receiver can be a multiple-input-multiple-output orthogonal-frequency-division-multiplexing (OFDM-MIMO) receiver that can be configured to increase the information-carrying capacity of a channel (i.e., increase the channel capacity) above and beyond a saturation capacity of the channel.

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 transmission method simultaneously transmitting a first modulated signal and a second modulated signal at a common frequency performs precoding on both signals using a fixed precoding matrix and regularly changes the phase of at least one of the signals, thereby improving received data signal quality for a reception device.

A method and apparatus for orthogonal frequency division multiplexing (OFDM) modulation includes separating a frequency-domain sequence of complex numbers into a first portion and a second portion that is disjoint with the first portion, each of the first portion and the second portion including a respective half of the complex numbers of the frequency-domain sequence, and generating a time-domain sequence having a real in-phase component that is a function of the first portion only, and an imaginary quadrature-phase component that is a function of the second portion only.

In one aspect, an apparatus includes: a fast Fourier transform (FFT) engine to receive orthogonal frequency division multiplexing (OFDM) samples of one or more OFDM symbols and convert the one or more OFDM samples into a plurality of frequency domain carriers; and a tone cancellation circuit coupled to the FFT engine to receive the one or more OFDM samples and generate a plurality of frequency carriers for the one or more OFDM samples, identify a highest magnitude frequency carrier of the plurality of frequency carriers, and remove tone interference from the OFDM samples based at least in part on the highest magnitude frequency carrier.