The present invention pertains to systems and methods for equalizing a digitally modulated input signal for transmission as an optical signal over an optical fiber. In detail, this equalization is accomplished prior to the signal's conversion to an optical signal, and prior to the signal being filtered by a vestigial sideband (VSB) filter. In particular, equalization is accomplished by giving weights to the taps of a tapped delay equalizer, wherein weights for respective taps are derived from the output signal after its conversion to a digital signal at the downstream end of the optical fiber.

A physical layer transceiver for connecting a host device to a wireline channel medium includes a host interface for coupling to the host device, a line interface for coupling to the channel medium, a transmit path operatively coupled to the host interface and the line interface, a receive path operatively coupled to the line interface and the host interface, and adaptive filter circuitry operatively coupled to at least one of the transmit path and the receive path for filtering signals on the at least one of the transmit path and the receive path, the adaptive filter circuitry including a non-linear equalizer. The non-linear equalizer may be a neural network equalizer based on a multi-layer perceptron or a radial-basis function, or may be a linear equalizer with a non-linear activation function. The non-linear equalizer also may have a front-end filter to reduce input complexity.

A decision-feedback equalizer (DFE) samples an input signal with respect to a gamut of p reference-voltage levels to place the symbol represented by the input signal within a voltage region. The DFE derives a set of tentative decisions for the voltage region, the set excluding at least one of the possible values for the symbol under consideration. A feedback stage then selects a final decision from among the tentative decisions.

A receiver includes: an A/D converter that performs an analog digital conversion of an input signal; an equalizer that equalizes an output from the A/D converter, eliminates inter code interference and obtains a data output; a timing recovery part that generates a recovery clock from the data output of the equalizer; a detector that detects the timing when an input signal varies from a no-signal state and has reached a predetermined threshold; and an initial phase setting part that sets as the initial phase of the recovery clock by the timing recovery part, a timing when the predetermined time has elapsed after the timing detected by the detector.

Described is a method of processing a signal received at an uplink control information (UCI) receiver in a wireless communication system. The method comprises processing a signal received on an uplink (UL) at said UCI receiver to transform said received signal into a likelihood calculation of possible transmitted codewords (θ.sub.1 . . . θi . . . θ.sub.N) and determining a maximum magnitude θ.sub.max value from said likelihood calculation. The method includes comparing said maximum magnitude θ.sub.max value to a selected, calculated or predetermined scaled threshold S.Math.τ where τ is a threshold and S is a scaling factor for the threshold τ. The comparison step is such that, where |θ.sub.max|.sup.2>S.Math.τ, the method comprises determining that the signal received comprises a linear block encoded signal. In the method, prior to said comparison step, the scaling factor S is selected from a plurality of scaling factor options. One scaling factor option (i) is a scaling factor S.sub.RE derived from a combination of estimated noise and/or signal power at an output of a resource element (RE) demapper module and an estimated channel response from/before an equalizer module of said UCI receiver. The options also include using a combination of S.sub.RE and a suitable scaling factor derived excluding option (i).

A transceiver may include a transmitter device, a receiver device, a secondary receiver device, and switching elements. The transmitter device may provide a transmit control signal on first and second channels. The receiver device may receive a receive control signal on the first and second channels. The secondary receiver device may monitor occupation of the first and second channels without decoding at least a portion of control signals concurrent with the receiver device receiving the receive control signal. The switching elements may control when the transmitter device provides the transmit control signal to one of and is electrically isolated from first and second antennas, the receiver device receives the receive control signal from one of and is electrically isolated from the first and second antennas, and the secondary receiver device monitors occupation of one of the first and second channels and is electrically isolated from the first and second antennas.

In a transmitter apparatus, a known reference signal is superimposed on top of a data signal that is typically not known a priori to a receiver and the combined signal is transmitted. At a receiver, an iterative channel estimation and equalization technique is used to recover the reference signal and the unknown data signal. In the initial iteration, the known reference signal is recovered by treating the data signal as noise. Subsequent iterations are used to improve estimation of received reference signal and the unknown data signal.

Embodiments of the present disclosure relate to a method and apparatus for optical communication. For example, there is provided a method implemented at a passive optical network device configured to perform high-rate communication via a bandwidth-limited link. The method comprises: receiving, via the bandwidth-limited link, a training signal from an optical network unit; obtaining a delay signal by delay-sampling the training signal; determining, based on the delay signal, a first channel response of the bandwidth-limited link, the first channel response characterizing change of the training signal caused by the bandwidth-limited link; and compensating, based on the first channel response, a communication signal received via the bandwidth-limited link from the optical network unit, to reduce distortion of the communication signal. A corresponding apparatus is also disclosed.

A method for distortion compensation in a transmission link comprising obtaining information of an amplitude distribution of a signal prior to being transmitted by a transmitter, receiving the transmitted signal at a receiver and determining a received signal amplitude distribution, comparing the received signal amplitude distribution to the amplitude distribution of the signal prior to transmission and using results of the comparison to estimate the AM/AM non-linearity in the transmitter.

A network transceiver device is provided, including at least two variable gain amplifiers (VGAs), and at least two sets of analog digital converters (ADCs), each set including ADCs coupled to an output of one of the VGAs, the sets being arranged in VGA-specific channels. The device includes a plurality of feed-forward equalizers (FFEs), each FFE being coupled to receive an output of one of the ADCs in one of the VGA-specific channels. Each FFE is configured to adaptively equalize the output received from the ADCs utilizing a first equalization coefficient subset with coefficient values that are common to all FFEs, and a second equalization coefficient subset that is channel specific and that has a first set of coefficient values for a first VGA-specific channel and a second set of coefficient values for a second VGA-specific channel, the sets of coefficient values being computed independently.