The invention relates to a MIMO-FBMC transmitter/receiver with linear precoding implemented in the frequency domain. In one embodiment, at the transmitter the linear precoding is performed (525.sub.1, . . . ,525.sub.KN) after filtering and spectral spreading, before the IFFT and combination of FBMC symbols in the time domain, such that the precoding does not introduce interference between data streams. In a second embodiment the linear precoding may be combined with the beamforming at transmission or at reception so as to spatially separate the data streams.

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.

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.

A method of designing a digital filter for example for use in an FBMC/OQAM telecommunications system, with a target overlapping factor and meeting a specified signal to interference ratio is described, whereby a candidate filter design defined by an impulse response, satisfying the Nyquist criterion and having an overlapping factor higher than the target is selected, and the time and frequency coefficients of its impulse response inverted to define a new filter design; and

truncating the impulse response defining said new filter design to the minimum number of coefficients achieving said specified signal to interference ratio.

A method of reception of signals transmitted by a FBMC transmitter using a block Alamouti coding. After demodulation in a base band, the received signal is sampled, with the sample blocks undergoing a sliding FFT before being de-multiplexed towards a first path during a first use of the channel and a second path during a second use of the channel. The vectors received on the first path are multiplied by a first and a second transfer matrix, conjugated to provide first and second vectors. The vectors received on a second path undergo time-reversal and complex conjugation and, if appropriate, multiplication by an imaginary factor, depending on the size of the blocks. The vectors thus obtained are multiplied by first and second transfer matrices to provide third and fourth vectors. The first and fourth (second and third vectors) are then combined and the combined vector is filtered and spectrally de-spread to give an estimate of the block transmitted by the first (second) antenna of the transmitter during the first use of the channel.

Method and device for configuring a waveform at a transmitter are provided. The method includes: receiving at least one input signal, each input signal corresponding to a subcarrier spacing setting; performing IDFT pre-processing to each input signal, the IDFT pre-processing including DFT pre-coding or offset modulation; performing IDFT to each input signal which is subjected to the IDFT pre-processing, the IDFT including an IDFT with parameters including resource mapping and a corresponding IDFT size; performing IDFT post-processing to each input signal which is subjected to the IDFT to obtain at least one output signal, the IDFT post-processing including cyclic extension and time-domain windowing; adding the at least one output signal in time domain; and transmitting the added signal through a corresponding antenna port. Waveforms are configured flexibly according to practical scenarios at the transmitter to determine a most suitable waveform for current scenario, which meets practical requirements of 5G technology.

A transmission method and an FBMC transmitter to transmit at least a first and a second block of symbols (X.sub.0, X.sub.1), each symbols block including a temporal sequence of L vectors with predetermined size N. It uses a first and a second FBMC modulation channel, each FBMC modulation channel being associated with an antenna. During a first use of the channel, the vectors of the first block and the vectors of the second block are input to the first and to the second FBMC modulation channels respectively, in the order of the temporal sequence. During a second use of the channel, the vectors of the first and second blocks are multiplied by a factor j.sup.L 1 respectively and −(j.sup.L 1) input to the second and to the first FBMC modulation channels respectively, in the inverse order of the temporal sequence.

Methods, systems, and devices for wireless communications are described. A transmitting device may modulate a first binary sequence using binary phase shift keying on a first axis of a complex plane. The device may modulate a second binary sequence using binary phase shift keying on a second plane of a complex axis. The first axis and the second axis may be orthogonal. The device may transmit the first binary sequence and the second binary sequence according to the modulation of the first binary sequence and the second binary sequence.

Systems and methods are directed to low cost and low power carrier frequency offset (CFO) estimation in a receiver. In-phase (I) and quadrature (Q) samples of a wireless signal are received by the receiver and a first phase and a second phase are extracted from the outputs of a first autocorrelator with a first time-lag and a second autocorrelator with a second time-lag. The extracted first and second phases are combined to generate an estimated CFO of high accuracy and wide estimation range.

In an orthogonal multicarrier radio transmission system complex-valued symbols are transmitted, wherein the real part and the imaginary part of each symbol are shifted against each other by one half symbol period and wherein a non-symmetric conjugate-root filter is applied to each symbol before transmission to mitigate inter-carrier interference and intersymbol interference. Corresponding reverse steps are performed at the receiver.