How to apply an Alamouti like space-time coding (or transmit diversity) to a Filter Bank Multicarrier (FBMC) transmission using Offset QAM (OQAM). In FBMC, due to the orthogonality in the real domain only, an intrinsic interference results thereof for the imaginary component. Simply adapting the Alamouti scheme to FBMC OQAM is not obvious since the intrinsic interference terms are not equivalent at each antenna since it depends on the surrounding symbols. The application proposes to use a precoding symbol chosen to cancel out (zero) the intrinsic interference individually for each antenna, ie a code rate of (sending one data symbol requires two time units). A more elaborated embodiment proposes to choose the contiguous precoding symbols such that a virtual QAM Alamouti scheme is achieved, without rate loss.

How to apply an Alamouti like space-time coding (or transmit diversity) to a Filter Bank Multicarrier (FBMC) transmission using Offset QAM (OQAM). In FBMC, due to the orthogonality in the real domain only, an intrinsic interference results thereof for the imaginary component. Simply adapting the Alamouti scheme to FBMC OQAM is not obvious since the intrinsic interference terms are not equivalent at each antenna since it depends on the surrounding symbols. The application proposes to choose contiguous precoding symbols such that a virtual PAM Alamouti scheme is achieved. Code rates of 1/2 or 2/3 are achieved depending on the number of precoding symbols needed per antenna.

The invention relates to precoding (or rather pre-equalisation) for a faster-than-Nyquist OFDM or OFDM/OQAM type transmitter. Compression of faster-than-Nyquist OFDM pulses over time introduces an inter-symbol interference (ISI) and a sub-carrier interference (ICI). Assuming a Gaussian-type channel (AWGN), the ISI and ICI can be estimated at the transmitter and, in this way, some of the symbols (at most half) can be precoded (according to the value of the adjacent symbols), such as to cancel the ISI and ICI introduced during transmission and reception.

A communication device encodes a plurality of information bits to generate a plurality of encoded bits, and maps the plurality of encoded bits to a plurality of constellation symbols, including mapping each bit to multiple constellation symbols. The communication device generates a plurality of orthogonal frequency division multiplexing (OFDM) symbols corresponding to a physical layer (PHY) data unit using the plurality of constellation symbols, wherein the OFDM symbols are generated such that: the OFDM symbols have a tone spacing that is of a tone spacing of a legacy wireless communication protocol, and the OFDM symbols span only a subband of a 20 MHz communication channel. The communication device generates a transmission signal using the plurality of OFDM symbols, the transmission signal spanning only the subband of the 20 MHz communication channel.

An FBMC transmission/reception system wherein a phase pre-compensation and an amplitude pre-compensation are done on a block of modulation symbols. The symbol block thus compensated is segmented into a number M of sub-blocks equal to the number of carriers of an FBMC modulator. The sub-blocks are divided into vectors with size N/2 and padded with isolation zeroes to form padded vectors with size N. Each of these padded M is processed by an IFFT to give time sequences to which cyclic prefixes and suffixes are added. The resulting cyclic sequences are then input to the M input channels of the FBMC modulator. The reception symbols can be recovered at the receiver by a simple FFT with size NM/2.

An FBMC signal transmitting method and receiving method, a transmitter, and a receiver are provided. The transmitting method includes: generating offset quadrature amplitude modulation OQAM symbols included on at least two subbands; mapping an OQAM symbol on each subband onto a respective subcarrier to obtain a frequency-domain signal, where a first frequency interval exists between adjacent subcarriers in a same subband, a second frequency interval exists between adjacent subcarriers that belong to two adjacent subbands, the second frequency interval is a sum of the first frequency interval and a guard band interval, and the guard band interval is a fractional multiple of the first frequency interval; generating an FBMC signal out of the frequency-domain signal; and transmitting the FBMC signal to a receiver.

This invention discloses a multicarrier communication system that includes a transmitter equipment and a receiver equipment. According to a timing scheme, the transmitter equipment processes multiple original symbols for transmission on multiple subcarrier channels, and the receiver equipment processes and detects multiple received symbols from the multiple subcarrier channels. During a time frame of data transmission, the initial three of the original symbols for each of the subcarrier channels are three pilot symbols, forming a preamble. The three preambles of every consecutive three of the subcarrier channels form a preamble unit. All the pilot symbols of the preamble unit are expressed as a 33 matrix. When the center pilot symbol of the preamble unit is normalized to 1 or j (i.e., the imaginary unit), the matrix is $\left[\begin{array}{ccc}-j& -j& -j\\ j& 1& -j\\ -j& j& -j\end{array}\right]\mathrm{or}[\begin{array}{ccc}1& 1& 1\\ -1& j& 1\\ 1& -1& 1\end{array}$

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.

The present disclosure relates to a pre-5th-Generation (5G) or 5G communication system to be provided for supporting higher data rates Beyond 4th-Generation (4G) communication system such as Long Term Evolution (LTE).

The application discloses methods and apparatuses for transmitting and receiving a preamble based reference signal. The method for transmitting a preamble based reference signal comprises: generating a main preamble sequence; generating an auxiliary preamble sequence, wherein, on a predefined resource, a synthesized signal of the main preamble sequence and the auxiliary preamble sequence is equal to a predefined preamble based reference signal; and transmitting the main preamble sequence and the auxiliary preamble sequence based on a filter-bank multi-carrier modulation. According to the embodiments of the application, the main preamble sequence and the auxiliary preamble sequence are appropriately designed so that the synthesized signal on the predefined resource is equal to the predefined preamble based reference signal. In this way, the predefined reference signal may be obtained at the receiving end by using the intrinsic interference of FBMC modulation, thereby making an efficient channel estimation.

Signal extrication of a pair of quadrature amplitude modulated signals, of a particular carrier frequency and phase constant, is accomplished by the use of a discriminator-mixer circuit, where the carriers and sidebands of the said pair of quadrature amplitude modulated signals are intermingled with similar and/or nondescript signals containing sinusoidal components and can not be selected for signal demodulation by normal detection means without distortion of the information carried by these signals, by equally splitting all input signals to the discriminator-mixer circuit into two independent circuit paths that contain identical components but one independent circuit path performs a complementary signal processing function with respect to the other independent circuit path resulting in a counterbalance between the two paths, thereby generally canceling all output signals of the said discriminator-mixer circuit, with the exception of the said pair of quadrature amplitude modulated signals which are not canceled because of the singular signal nullification property of a product detector circuit, that is a component in each of the said independent circuit paths, by the use of heterodyne techniques between the input signals to the said product detectors and the synchronized local oscillator output pair of quadrature sinusoidal signals of the said particular frequency and phase constant, that cause a counterbalance null in each of the two paths and allowing only the said desired pair of quadrature amplitude signals to appear at the output of the discriminator-mixer circuit.