A method of implementing Orbital Angular Momentum (OAM) for radio communications in general and LTE in particular. Common prior art so far recreate the vorticity (axial rotation of the Poynting vector) by using ring-shaped antenna arrays. This application proposes to create the vorticity in signal processing without the need of any space diversity (i.e. work with a single antenna). An Hilbert transform is applied in frequency domain to the Fourier transform of the analytical representation of a band-limited OFDM signal. The Hilbert transform is then approximated by a development in series into orthogonal twisted modes. This can be seen as an inverse Fourier transform of the complex analytical signal. Therefore an OAM IFFT based transmitter is proposed where parallel IFFTs are performed for each OAM mode and superimposed.

A system combining OFDM standard modulation with a superimposition of Orbital Angular Momentum modes, each OAM modes consisting in an overlapping decimated IFFTs with the main mode standard OFDM signal, Orthogonality of the OAM modes is assessed, A frame structure embodying both main mode OFDM samples and overlapping OAM modes is proposed.

Chromatic dispersion is pre-compensated in a direct-detected orthogonal frequency-division multiplexed optical transmitter through digital signal processing methods, to generate signals that can be transmitted over an optical fiber. The dispersion pre-compensation digital signal processing may include multiplying subcarriers by a respective factor. The dispersion pre-compensation digital signal processing may instead include application of a finite impulse response filter to signals. The dispersion pre-compensation digital signal processing may instead include fast Fourier transformations of signals, application of a frequency domain filter to signals generated by the fast Fourier transformations, and inverse fast Fourier transformations of the signals produced by application of the frequency domain filter.

A method is provided for pre-distorting an optical signal, intended to be transmitted over an optical transmission line and including a plurality of frequency division multiplexed optical sub-carriers. The optical signal is obtained from an optical conversion of an electrical signal including a plurality of frequency division multiplexed sub-carriers. This method includes obtaining a plurality of corrective factors, corresponding to the electrical sub-carriers, as a function of a plurality of values, determined for the optical sub-carriers, of a first parameter dependent on the power of the sub-carriers, and application of the corrective factors to the amplitudes of the corresponding electrical sub-carriers, so as to equalize, at the output of the optical transmission line, the values of the first parameter for the sub-carriers of the optical signal.

A system and method for receiving communication signals that have been spread in two dimensions. The method includes receiving signals representative of data that has been two-dimensionally spread and transmitted over a communication channel. The method further includes processing the signals to determine equalization coefficients based upon a two-dimensional time-frequency impulse response of the communication channel. A two-dimensional signal equalization procedure is then performed using the equalization coefficients.

A radio communications method includes carrying out, by a transmitter: providing a digital time signal carrying digital symbols to be transmitted; and transmitting a radio frequency signal carrying the digital time signal. The method further includes carrying out, by a receiver: receiving the radio frequency signal transmitted by the transmitter; processing the received radio frequency signal to obtain a corresponding incoming digital signal; and extracting, from the incoming digital signal, the digital symbols carried by the incoming digital signal. The digital time signal carrying the digital symbols to be transmitted results from an approximation of the Hilbert transform in frequency domain, which approximation is based on a frequency main mode and one or more frequency twisted modes, wherein the frequency main and twisted modes carry, each, respective digital symbols to be transmitted.

A transmission device that improves data reception quality includes: a weighting synthesizer that generates a first precoded signal and a second precoded signal from a first baseband signal and a second baseband signal, respectively; a phase changer that applies a phase change of i to the second precoded signal; an inserter that inserts a pilot signal into the second precoded signal applied with the phase change; and a phase changer that applies a phase change to the second precoded signal applied with the phase change and inserted with the pilot signal. satisfies /2 radians<< radians or radians<<3/2 radians. Each of the first baseband signal and the second baseband signal is modulated via a modulation scheme of quadrature amplitude modulation (QAM) using non-uniform mapping.

A repeater includes: a forwarding entity; and a mobile termination configured to receive first indication information for controlling an access link beam of the forwarding entity, the first indication information including first information for indicating one or more first time-domain resources corresponding to one or more access link beams, the first time-domain resources being related to a first subcarrier spacing and/or a second subcarrier spacing.

Provided are a signal processing method, a communication device, a storage medium, and a program product. The method includes: determining a first subcarrier set and a second subcarrier set in to-be-transmitted information, where a first time domain sequence corresponding to the first subcarrier set is obtained according to communication information; obtaining a projection signal according to a vector corresponding to a first dataset and a target signal, where the first dataset includes at least part of data in the first time domain sequence corresponding to the first subcarrier set; obtaining a second time domain sequence corresponding to the second subcarrier set according to the projection signal; superimposing the first time domain sequence and the second time domain sequence to obtain a time domain signal corresponding to the to-be-transmitted information; and sending the time domain signal.

A data transmission method includes transmitting to-be-transmitted data in N frequency domain resource blocks, where each of the N frequency domain resource blocks includes K(n) subcarriers, where n=1, 2, . . . , N, N is greater than or equal to 1, and K(n) is greater than or equal to 1; performing inverse Fourier transform and an upsampling operation on the to-be-transmitted data in each of the N frequency domain resource blocks to form N groups of data sequences; and transmitting the N groups of data sequences.