Texas Instruments Corporation

Altair Semiconductor Ltd.

Itay Lusky

Naftali Sommer

Ariel Yagil

Yigal Bitran

Ofir Shalvi

Daniel Wajcer

Zvi Reznic

Yosef Bendel

Eli Haim

Liran Brecher

Lior Ophir

Mor Miller

Nohik Semel

Ran Senderovitz

Amir Peleg

Rafi Dalla Torre

Daniel Sharon

Kobi Haim

A communication terminal includes a Radio Frequency (RF) unit and a baseband processor. The baseband processor is coupled to receive from the a servicing base station (BS) information indicating an extent of synchronization between the servicing BS and at least one other BS of the wireless communication network, and to process received signals, responsively to the extent of the synchronization specified in the received information, so as to cancel interference caused to the signals received from the servicing BS by signals transmitted by the at least one other BS.

Time synchronization in wireless communication networks

A method for communication includes receiving a spatially-multiplexed signal using multiple receivers to produce multiple respective received signals. The spatially-multiplexed signal includes multiple simultaneously-transmitted symbols, which are selected from respective sets of constellation symbols, each constellation symbol representing a respective set of values of a group of data bits. Combinations of the constellation symbols are traversed iteratively. Each combination includes one constellation symbol from each of the sets of the constellation symbols and represents N data bits. The traversed combinations are searched for a combination that matches the received signals. During traversal of the combinations, at least 2N measures of likelihood regarding the values of the data bits represented by each traversed combination are accumulated. The accumulated measures of likelihood are processed to produce soft bit metrics. The values of the data bits carried by the multiple transmitted symbols are reconstructed responsively to the soft bit metrics.

Efficient decoding of spatially-multiplexed signals

A communication terminal includes a Radio Frequency (RF) unit and a baseband processor. The RF unit is operative to receive signals from a Base Station (BS) of a wireless communication network using a communication protocol that defines time frames divided in a time domain into zones. Each zone corresponds to a respective communication mode between the BS and the terminal and occupies respective time intervals within the frames. The baseband processor is coupled to receive from the BS via the RF unit synchronization information indicating whether the time intervals allocated to at least a given zone by the BS and by at least one other BS of the wireless communication network are synchronized with one another, and to process the signals received from the BS so as to cancel, responsively to the synchronization information, interference caused to the signals by the at least one other BS.

Zone synchronization in wireless communication networks

A novel and useful mechanism for the detection, estimation and correction of far-end cross talk (FEXT) caused by transmissions over adjacent wire pairs or cables. The detection, estimation and correction technique of the invention can be used to identify and compensate for FEXT impairments in Ethernet and DSL systems. The detection, estimation and correction is performed utilizing one of several techniques including linear forward filtering, backward decision feedback based filtering and a combination thereof. Results of simulations are presented illustrating the performance improvements provided by the present invention.

Far-end crosstalk (FEXT) canceller

A novel and useful mechanism for the detection and estimation of far-end cross talk (FEXT) caused by transmissions over adjacent wire pairs or cables. The detection and estimation technique of the invention can be used to identify FET impairments in Ethernet and DSL systems. The detection and estimation scheme is performed utilizing an adaptive FEXT canceller filter for detection purposes during normal operation of the system. FEXT filter tap coefficients are determined one at a time using a mechanism shared amongst all taps. Once adapted, the filter coefficients can be used to estimate FEXT strength and to determine spectral measurements of the FEXT impairment noise.

Apparatus for and method of far-end crosstalk (FEXT) detection and estimation

A novel apparatus for and method of estimating the cable length of an active network link. The cable diagnostics mechanism of the invention is particularly suited for use in estimating the length of Ethernet network between two edges when the link is active, i.e. data is being transmitted in both directions simultaneously and the transmission of test pulses is not possible. The cable length estimation mechanism of the present invention is based on a well-known property of the spectrum of the insertion loss of the cable, namely, the linear relationship between the attenuation of the cable at a given frequency in decibels and the cable length. Information characterizing this relationship is extracted and used to determine the length of the cable.

Active link cable diagnostics

A novel and useful baseline wander correction mechanism for use with transformer coupled baseband communication receivers. Parametric estimation of the transformer model is used estimate and cancel the baseline wander effect. A parametric model is used to model the baseline wander impairment created by the transmitter and receiver transformers as a high pass filter having an exponential decay parameter alpha. A correction signal for both the far end and echo signal paths are calculated and summed to generate a total correction signal. The total correction signal is partitioned into an analog correction signal that is applied to the analog portion of the communications receiver and into a digital correction signal that is similarly applied to the analog portion of the communications receiver.

Baseline wander correction for communication receivers

A novel mechanism for sharing filter taps across a plurality of interference cancellers. Each interference canceller may be directed to impairment, such as Ethernet impairments, including Ethernet 1000Base-T impairments. Various interference impairments include echo cancellation, NEXT cancellation and/or other interference detection or cancellation, etc. The hardware requirements of the interference impairment cancellers are reduced by sharing filter taps among the cancellers. In a first embodiment, the taps from a unified filter tap bank are shared across all the interference impairment cancellers for all four channels and over all ports. In a second embodiment, a portion of the taps of each filter are shared wherein each canceller comprises a fixed filter tap portion and a shared filter tap portion. A tap allocation algorithm assigns taps to those cancellers that need them the most. A canceller configuration is selected that yields maximal interference mitigation and the taps are allocated accordingly.

Interference canceller tap sharing in a communications transceiver

The present invention provides an encoding method and a class of decoding methods that provide methods for high throughput and high robustness digital communications over channels that are contaminated by impulse noise, as well as white and colored additive noise (noise that is characterized by heavy-tailed distribution), phase noise and signal fading.

Method for upstream CATV coded modulation

A system is provided to automatically estimate performance of a receiver for receiving input signals, the input signals having a carrier frequency and a baud rate, from a channel in a communication system and the effect of highly correlated noise cancellation on performance of the receiver, while no active transmission is occurring on the channel, comprising: a digital front end in the receiver for receiving samples of the input signals; a predictor coupled to the digital front end for predicting highly correlated noise in a second sample of the input signal; and a subtraction unit coupled to the predictor for subtracting the predictor output from the second sample to determine residual noise in the second sample. Other systems and methods are disclosed.

Noise analysis in a communication system

Systems and methods for automatic gain control are disclosed. In one aspect of the invention, a system is provided that comprises a programmable gain amplifier that amplifies an input signal based on a gain signal. The system further comprises an analog-to-digital converter that generates at least one digital output signal from the amplified input signal, and an automatic gain control component that determines an adjustment of the gain signal based on a comparison of the at least one digital output signal to a predetermined maximum amplitude reference level.

Systems and methods for automatic gain control

A method is provided for automatically improving throughput of an active channel in a communication system comprising: receiving input from one or more modules that identify and characterize impairments in the active channel; monitoring the input to track changes in the impairments; and changing channel parameters to improve throughput on the channel based on the changes in the impairments. Other systems and methods are disclosed.

Channel monitoring for improved parameter selection in a communication system

A method is provided to provide data to automatically estimate channel performance in a communication system if a different order constellation is used comprising the steps of: receiving an input signal from the channel; passing the input signal to a slicer having an output signal; determining signal noise by taking the difference between the input signal and output signal; identifying a beginning of a noise event when the signal noise is greater than a predefined first threshold; identifying an end of a noise event when the signal noise is less than a predefined second threshold; and providing for output the beginning of the noise event and the end of the noise event. Other systems and methods are disclosed.

Constellation selection in a communication system

A method provides frequency and phase offset estimation in a SCDMA burst receiver (such as a DOCSIS 2.0 SCDMA burst receiver) by application of the known Least Square (LS) parameter estimation algorithm to a pre-known transmitted sequence, called preamble, in order to optimally characterize the phase and frequency offsets affecting the transmitted data. The LS parameter estimation algorithm is adapted to SCDMA burst receiver specifications by changing index calculations to fit according to SCDMA preamble locations. Improved estimation accuracy can be achieved by using weighted least squares that disregard symbols affected by impulse and burst noise. Weighted least squares can further impart more weight to last symbols to more accurately estimate contemporary impairments. The method is particularly useful for communication systems having large frequency and phase offsets as in the DOCSIS 2.0 SCDMA burst receiver.

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Hod Hasharon, Israel

Itay Lusky