Wireless communication transmission and reception techniques are described. At transmitter, source data bits are modulated into a number Nd of constellation symbols. An invertible transform is applied to the constellation symbols, thereby resulting in mapping the transformed symbols into Nd elements in the time-frequency grid. A signal resulting from the invertible transform is transmitted over a communication channel.

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.

A modulator operable to control an oscillator is described. The modulator can include a memory that stores oscillator control values and a bit streaming block. The bit streaming block can generate a bit stream based on the oscillator control values and transmit the bit stream to the oscillator to control an oscillation frequency of the oscillator. The modulator can also include a bit streaming loader (BSL). The BSL can receive one or more of the oscillator control values from the memory, generate one or more corresponding bit values based on the one or more of the oscillator control values, and provide the one or more bit values to the bit streaming block. The bit streaming block can then generate the bit stream based the one or more bit values generated by the BSL.

Certain aspects of the present disclosure provide techniques for hybrid modulation and demodulation, which may include multiplexing and demultiplexing different waveform types. An example method includes receiving a time-domain waveform from a transmitting entity and converting the time-domain waveform to a frequency domain. The method also includes identifying a first set of time and frequency resources associated with converted first information and a second set of time and frequency resources associated with second information in time and frequency resources of an orthogonal frequency domain multiplexing (OFDM) resource grid in a time-frequency domain. The method further includes decoding the first set of time and frequency resources to generate first information from the converted first information. For certain aspects, the first information may be precoded with an orthogonal time frequency space (OTFS) modulation.

The invention describes a method and an arrangement for transmitting an optical transmission signal with reduced polarization-dependent loss. A first transmission signal component and a second orthogonal transmission signal component of the optical transmission signal are transmitted with a time difference between said transmission signal components.

Aspects of the present invention include apparatus and methods for transmitting and receiving signals in communication systems. A multicarrier generator generates a multicarrier signal. An optical demultiplexer separates the multicarrier signal into separate multicarrier signals. At least one QPSK modulator modulates signals from the separate multicarrier signals. An optical multiplexer combines the QPSK modulated signals into a multiplexed signal. The multiplexed signal is then transmitted.

An apparatus is described which uses directly modulated InGaN Light-Emitting Diodes (LEDs) or InGaN lasers as the transmitters for an underwater data-communication device. The receiver uses automatic gain control to facilitate performance of the apparatus over a wide-range of distances and water turbidities.

A method for transmitting data through a multi-media communication network includes converting transmission entities into data symbols at a first communication device, transmitting the data symbols from the first communication device to a second communication device through at least two different types of communication media using only lower PHY layers of the at least two different types of communication media, and converting the data symbols into transmission entities at the second communication device. A network implementing a universal data link includes a first communication device configured to convert transmission entities into data symbols, a second communication device configured to convert the data symbols into transmission entities, at least a first communication medium and a second communication medium communicatively coupled between the first communication device and the second communication device, and a first physical-layer translator configured to translate data symbols without converting the data symbols into transmission entities. In order to reduce processing time and end-to-end latency, the physical-layer translator only performs demodulation and modulation operations, optionally also equalization.

An apparatus and method for measuring frequency response characteristics of an optical transmitter and an optical receiver where the apparatus includes: a generating unit configured to generate a driving signal for driving the modulator of the optical transmitter, which comprises at least two frequencies; and a calculating unit configured to respectively calculate the frequency response characteristics of the optical transmitter and the optical receiver according to output signal components in output signals of the optical receiver corresponding to at least two detection signal components of identical amplitudes and different frequencies in detection signals. The frequency response characteristics of the optical transmitter and the optical receiver may be obtained, the amplitude responses and phase responses in the frequency response characteristics may be respectively obtained, and the measurement results are accurate and reliable.

A satisfactory list detection (LD) receiver based on spatial modulation (SM) orthogonal frequency division multiplexing (OFDM) waveform is provided. In some embodiments, the LD receiver can implement a suboptimal LD detection process that relies on a reduced search space an optimal joint ML detection-based process for the SM-OFDM transmission mode. In some aspects, the overall search space for the optimal joint ML is determined by the total spectral efficiency, which can be divided into two information categories with two different search spaces defined by the number of bits of each category. As such, in some aspects, the LD receiver can permit detecting, with reduced complexity, antenna bits and data bits based on a determination of respective log-likelihood ratios.