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.

A system that includes combiner circuitry configured to combine a first signal and a second signal to generate a third signal, wherein said third signal is output for transmission onto a communication medium. The system also includes nonlinearity modeling circuitry configured to model a nonlinear response of a nonlinear circuit, and generate a fourth signal through nonlinear distortion of a fifth signal using said model. The system also includes bin modification circuitry configured to generate said second signal through application of one or more weighting factors to frequency bins of said fourth signal, or of a transformed version of said fourth signal, and determine said weighting factors based on a difference, or squared difference, error metric.

Methods, systems, and devices for wireless communications are described for optimizing index modulated (IM) communications between a user equipment (UE) and a base station. The UE may identify a quantity of subcarriers for IM communications and transmit a message including an indication of the quantity of subcarriers to the base station. In some examples, the UE may transmit an indication of one or more subcarriers to exclude from IM communications. The base station may receive the indication of the quantity of subcarriers and/or the indication of the blacklisted subcarrier(s) and may determine a number of active subcarriers to be used based on at least the indication of the quantity of subcarriers. The base station may transmit an indication of the number of active subcarriers to the UE. The UE may process one or more received IM downlink signals based on the quantity of subcarriers.

The present disclosure relates to multi-MAC controller and single PHY systems and methods. An example method may include transmitting, via a first device in a Data Over Cable Service Interface Specification (DOCSIS) network, a first block of data within a first time slot and at a first power level, the first power level being based on an attenuation of a first network tap device associated with the first device. The example method may also include transmitting, via a second device in the DOCSIS network, a second block of data within the first time slot and at a second power level, the second power level being based on an attenuation of a second network tap device associated with the second device, the first power level being different than the second power level.

A method and structure for equalization in coherent optical receivers. Block-based LMS (BLMS) algorithm is one of the many efficient adaptive equalization algorithms used to (i) increase convergence speed and (ii) reduce implementation complexity. Since the computation of the equalizer output and the gradient of the error are obtained using a linear convolution, BLMS can be efficiently implemented in the frequency domain with the constrained frequency-domain BLMS (FBLMS) adaptive algorithm. The present invention introduces a novel reduced complexity constrained FBLMS algorithm. This new approach replaces the two discrete Fourier transform (DFT) stages required to evaluate the DFT of the gradient error, by a simple frequency domain filtering. Implementation complexity can be drastically reduced in comparison to the standard constrained FBLMS. Furthermore, the new approach achieves better performance than that obtained with the unconstrained FBLMS in ultra-high speed coherent optical receivers.

A signal generator 10 generates an OOK (on-off keying) modulation signal by mapping a CAZAC (constant amplitude zero auto-correlation) sequence to N subcarriers (N being an integer that is greater than or equal to 2) arranged at a determined interval among M subcarriers (M being an integer that is greater than or equal to 3) that are adjacent in the frequency domain, carrying out inverse fast Fourier transform (IFFT) processing on the mapped CAZAC sequence, and carrying out Manchester coding on a time domain signal generated by the IFFT processing. A radio transmitter 107 transmits the OOK modulation signal.

Methods, systems, and devices for wireless communications are described. Pre-discrete Fourier transform (DFT) time-domain spreading codes may be applied for UE multiplexing for uplink control information (e.g., over shared resources of an uplink slot). For example, a moderate number of UEs may be multiplexed within the same slot by having each UE spread modulation symbols before DFT-spreading by different spreading code. For orthogonality across UEs, the pre-DFT spreading codes may be selected as orthogonal cover codes (OCCs). The spreading sequences can be generated from a set of any orthogonal sequences or generated from unitary matrices. In some cases, orthogonality in the time domain may be kept as well as a frequency division multiplexed (FDM) structure in the frequency domain. For such property, a Fourier basis OCC design may be used. In some other examples, a Hadamard matrix based OCC design may be used.

Exemplary embodiments include methods for receiving device-to-device (D2D) data transmissions from a second user equipment (UE) in a radio access network (RAN). Embodiments can include receiving, from the second UE, a first data transmission. Embodiments can also include determining whether the first data transmission was correctly received. Embodiments can also include determining a first set of frequency-domain parameters to use for generating a time-domain sequence. In some embodiments, the set of frequency-domain parameters can comprise a basic frequency-domain sequence, a width (X), and an offset (Y). Exemplary embodiments can also include transmitting, to the second UE using a time-domain sequence generated from the first set of frequency-domain parameters, a first hybrid ARQ (HARQ) indicator of whether the first data transmission was correctly received. Other exemplary embodiments include complementary methods performed by second (data-transmitting) UEs, and UEs configured to perform operations corresponding to exemplary methods.

A method of modulating a series of input digital symbols of a first modulation scheme is provided. The method is implemented by a transmitter and includes receiving a sequential series of samples of the digital symbols in a first domain of the first modulation scheme. The first domain is one of the time domain and the frequency domain. The method further includes determining a dual of the first modulation scheme. The dual has a second modulation scheme in a second domain that is different from the first domain the second domain is the other of the time domain and the frequency domain. The method further includes applying a 90 degree rotational operation to the second modulation scheme to generate a rotational modulation format, modulating the series of digital symbols with the generated rotational modulation format, and outputting the modulated series of digital symbols to a receiver.

Embodiments of a method and an apparatus for wireless communications are disclosed. In an embodiment, a method for wireless communications involves generating a Physical Layer Protocol Data Unit (PPDU) that includes a resource unit (RU), wherein a size of the RU is less than a signal bandwidth and wherein data corresponding to the RU is distributed onto a disjoint set of subcarriers included in a frequency unit, and transmitting the PPDU using the disjoint set of subcarriers in accordance with a power spectrum density (PSD) limit.