Described herein is a system and method for determining one or more data modulation profiles for one or more devices. The system and method described herein may measure signal quality, such as a modulation error ratio (MER), signal-to-noise ratio (SNR), receive power, transmit power, etc. Based on the signal quality, the system may determine one or more data modulation profile(s) (e.g., quadrature amplitude modulation (QAM) profiles) for a subcarrier, a plurality of subcarriers, a device, and/or a grouping of devices.

A receiver estimates a vector of emitted symbols over a MIMO transmission channel which is emitted by emitting antennas. The receiver receives a vector of received symbols on receiving antennas. Estimation of the vector of emitted symbols is made by calculating a metric associated with a criterion for each vector of a subset of all possible vectors of emitted symbols and selecting an estimation for said vector of emitted symbols as the vector of emitted symbols among said subset which minimizes said metric.

A synchronizing radio receiver is disclosed, comprising: an analog baseband receive chain and a digital baseband receive chain. The digital baseband receive chain may comprise an analog to digital converter, a frame synchronization module, a frequency synchronization module, and an orthogonal frequency division multiplexing (OFDM) demodulator, wherein the frequency synchronization module is configured to cross-correlate a plurality of in-phase and quadrature samples to generate a synchronization signal and output the synchronization signal to a local oscillator in the analog baseband receive chain. The digital baseband receive chain may also further comprise a carrier frequency offset (CFO)/sampling frequency offset (SFO) correction module coupled to a frequency synchronization module configured to cross-correlate a plurality of in-phase and quadrature samples, with the CFO/SFO correction module configured to apply correction in a digital domain before outputting a corrected signal to the OFDM demodulator.

Embodiment reduced-state trellis equalization techniques compute accumulated path metrics (APMs) for a subset of candidate states for at least some stages in the trellis based on a neighborhood map of an ML state. This reduces the number of APMs that are computed and stored during trellis equalization. Other embodiments select a subset of candidate states for which APMs are transported to the next stage of the trellis based on the neighborhood map. This eliminates the need to sort the remaining APMs during reduced state trellis equalization. The neighborhood map identifies a subset of the highest probability neighbors for an ML state. The subset of candidate states identified as highest probability neighbors may be saved in a look-up table. The look-up table may be generated offline and/or generated/updated dynamically during run-time operation.

An apparatus, method, computer readable medium, and system are provided to generate a symbol placement associated with a transmission scheme by transforming a retrieved set of equalization coefficients. Symbols included in the symbol placement may be analyzed and quantified in terms of their distance from a decision boundary. Symbols may be synthesized on an iterative basis in order to obtain visibility into the underlying performance of the transmission scheme over time. If equalization is unable to reduce a signal impairment below a threshold value within a predetermined amount of time, then a determination may be made that a non-linear distortion source is present in a network or communication system. Signals received from a plurality of user terminals may be compared with one another in order to determine a probable location or cause of the non-linear distortion.

An improved non-OFDM communication system and method replaces an FFT at the receiver with an alternative processing configuration. The use of dense subcarriers and assigning A, B pairs based upon a pre-assigned QAM bit-mapped constellation will be maintained as with traditional OFDM. However, the receiver sample-rate is independent of subcarrier frequency-separation, and the system does not maintain separate real and imaginary signals at the transmitter and receiver. The system also processes receiver samples incrementally without awaiting the end of the modulation cycle, and uses incrementally-processed data to characterize disruptions introduced by the channel so as to better adapt to these disruptions. The system has the potential to increase signal throughput by a factor of two by re-using one of the freed-up information paths previously used by the real and imaginary signals.

A communications system includes RF processing circuitry for receiving a plurality of data streams and processing the plurality of data streams to associate with each of the plurality of data streams an orthogonal function to cause each of the plurality of data streams to be mutually orthogonal to each other on an RF link to enable transmission of each of the plurality of data streams on the RF link at a same time. Optical processing circuitry receives the plurality of data streams and processes the plurality of data streams to associate with each of the plurality of data streams the orthogonal function to cause each of the plurality of data streams to be mutually orthogonal to each other on an optical link to enable transmission of each of the plurality of data streams on the optical link at a same time. Switching circuitry multiplexes between the RF link and the optical link responsive to operating conditions on the RF link and the optical link.

Networks operating at high frequencies in 5G and 6G may reduce the incidence of phase faulting by declaring that, above a specified frequency, messages are to be modulated according to multiplexed amplitude-phase modulation, instead of the QAM modulation generally used at lower frequencies. Multiplexed amplitude-phase modulation can provide larger phase margins than QAM of the same order, by arranging the modulation phase levels to be equally spaced-apart which they are not in QAM. For example, with 4 amplitude and 4 phase levels (16 states), the various modulation states can be separated by 90 degrees of phase, whereas in 16QAM the minimum phase separation is only 36.9 degrees, a serious problem at higher frequencies where phase noise predominates. In addition, QAM cannot accommodate non-square modulation tables, which are readily provided by amplitude-phase modulation, further enhancing fault-mitigation options.

A dual-polarization, 2-subcarriers code orthogonal, orthogonal frequency division multiplexed signal carrying information bits is transmitted in an optical communication network without transmitting a corresponding pilot tone or training sequence. A receiver receives the transmitted signal and recovers information bits using a blind equalization technique and by equalizing the 2-subcarriers OFDM signal as a 49-QAM signal in time domain with a CMMA (constant multi modulus algorithm) equalization method.

A blind equalizer apparatus includes a decision-directed (DD) least mean squares (LMS) blind equalizer. A blind equalizer apparatus includes: a DD LMS blind equalizer, wherein: the blind equalizer uses a finite impulse response filter with tap weights that are adaptively updated using a filter tap update algorithm, wherein blind equalization of one of an in-phase (I) channel and a quadrature (Q) channel is carried out by maximizing the Euclidean distance of binary modulated waveforms, wherein the blind equalizer averages a block to compute an independent phase estimate for a block, wherein the blind equalizer computes an error variable for a block from the phase estimate for the block, wherein the blind equalizer uses the phase estimate and alternating I/Q one dimensional/binary slicing to make a hard decision, and wherein the blind equalizer uses the hard decision to derive an error variable that is used to update the filter tap weights.