Intel Corporation

Level One Communications, Inc.

Texas Instruments Corporation

Stanley K Ling

Hiroshi Takatori

Sumeet Sandhu

John R Camagna

Chris Heegard

William J Chimitt

James Ward Girardeau, Jr

Qinghua Li

Xintian Eddie Lin

Ashoke Ravi

Georgios Yorgos Palaskas

Keith A Holt

Yongfang Guo

Raymond C Blackham

Richard B Nicholls

Amit Gattani

Melanie Daniels

Soumyanath Krishnamurthy

Jorge Myszne

Ping An

David Carasso

Eric J Rossin

A multiple output transmitter is configured for transmitting a single input data stream over two or more spatial channels using OFDM signals. The transmitter includes a commutator to select bits from the single input data stream for two or more bit streams and two or more encoders each to encode bits of one of the bit streams. The commutator operates at a bit rate and sequentially provides the selected bits of the input data stream to the encoders. A spatial bit sequencer selects groups of encoded bits from each of the encoders and assigns individual bits of a selected group at the bit-rate to block permuters in a sequential manner to distribute bits from the selected group across the block permuters. The block permuters produce interleaved blocks of bits for an associated spatial stream. The commutator assigns bits of the input bit stream to more than one encoder to allow each encoder to operate at a lower rate.

Multiple-output transmitter for transmitting a plurality of spatial streams

Embodiments of methods and means for passively emulating channels in a multiple-input multiple output (MIMO) system are provided. Such embodiments include passively splitting a plurality of radio frequency signals into a greater plurality of such signals. Each of the greater plurality of radio frequency signals can then be selectively and passively attenuated, delayed and/or phase shifted. The resulting modified radio frequency signals are then recombined crossed over channels and coupled to a plurality of output nodes. Economical and versatile device and system testing is thus facilitated in a low-noise radio frequency environment without the need for complex up/down frequency or analog/digital conversions.

MIMO passive channel emulator

Techniques are presented for improving packet detection within a wireless device in the presence of platform noise. In some embodiments, packet detection is carried out by first performing a correlation operation using a signal at an input of a wireless receiver. The result of the correlation may then be compared to a threshold value in order to make a packet arrival decision. The threshold value may be varied during device operation in a manner that enhances packet detection performance.

Packet detection in the presence of platform noise in a wireless network

A multichip transceiver operates as part of a multiple-input multiple-output communication system. First receiver circuitry on a first integrated circuit processes radio-frequency (RF) signals received from a first signal source, and second receiver circuitry on a second integrated circuit processes RF signals received from a second signal source. Clock-signal generating circuitry provides clock signals through phase-matched paths to the first and second receiver circuitry.

Multiple-input multiple-output multichip transceiver with correlated clock signals

A multicarrier transmitter performs bit-interleaving suitable for transmitting more than one spatial stream over a multicarrier communication channel. The multicarrier transmitter may include a bit-grouping shifter to shift QAM symbol-bit groupings of a spatial stream among subcarriers of the multicarrier communication signal, and a bit-position permuter to rotate bits among bit positions within subgroupings of the QAM symbol-bit groupings of the second spatial stream.

Multiple output multicarrier transmitter and methods for spatial interleaving a plurality of spatial streams

The present invention provides a method and apparatus for selectively updating an adaptive element in a communications receiver based on a determination that the received data is accurate. When inaccurate data is received, the system determines that using that data to update the adaptive element will not be beneficial and excludes the data from being sent to the adaptive element. One mechanism for determining that data has been incorrectly received is the calculation of syndromes as part of a Forward Error Control (FEC) system. Detection of errors through use of the syndrome calculation can be supplemented through windowing to make a determination as to whether a number of received bits should be used or disregarded by the adaptive element. The adaptive element can comprise any number of decision-directed loops including adaptive processors and carrier and timing recovery loops.

Reliable decision directed adaptation in a communication system employing forward error control

An adaptive equalizer processes an input signal that includes noise, pre-cursor intersymbol interference, and post-cursor intersymbol interference. The adaptive equalizer includes a feedforward filter which reduces the pre-cursor intersymbol interference and whitens the noise, a feedback filter which detects the post-cursor intersymbol interference in a signal that corresponds to the input signal, and circuitry which removes the detected post-cursor intersymbol interference from the input signal. The feedforward filter includes separate first and second coefficients. The first coefficients reduce the pre-cursor intersymbol interference and the second coefficients whiten the noise.

Adaptive equalizer

In one embodiment of the invention, a tap-leakage generator includes an error filter and an updater. The error filter filters a decision error provided by the adaptive filter using a leakage factor. The adaptive filter has N taps. The updater updates N equalizer coefficients to the N taps using the filtered decision error. The updater receives N equalizer data from the N taps.

Adaptive filtering with tap leakage using error filtering

A method and apparatus for decision-directed adaptation for coded modulation is presented in which a modulation decoder and data re-encoder are used to create an estimated version of a received signal based on the use of a reliable modulation code. An adaptive equalizer is used to process the received signal, and the differences between the received signal passed through the adaptive equalizer and the estimated version are used by the adaptive equalizer to set the equalizer coefficients. A variety of adaptation algorithms can be used including Least Mean Squares (LMS) and Recursive Least Squares (RLS).

Decision-directed adaptation for coded modulation

A digital timing recovery system wherein the rate conversion is independent of the sampling rate, and which may be set in a network mode or a remote mode. The invention includes a transceiver core for processing transmit and receive data at a predetermined baud rate, an analog front end for transmitting and receiving analog signals over a network, a phase detector for generating a phase error estimate and a timing controller for receiving the phase error estimate signal and generating a receive and transmit phase control signal for controlling timing of the analog front end. A selector is provided for selecting a remote mode of operation or a network mode of operation. The analog front end further includes a transmit converter for converting the transmit data at the baud rate to a digital output at a transmit rate and a digital to analog converter for converting the digital output to an analog signal, and an analog to digital converter for converting the analog receive signal to a digital receive signal and a receive converter for converting the digital receive signal at a receive rate to the baud rate. The phase detector includes a channel estimator for generating a coefficient error signal and the timing controller includes a loop filter for producing a control signal for a numerically controlled oscillator that produces a baud interrupt signal and the phase control signals.

Apparatus for recovering timing of a digital signal for a transceiver

An activation method for adaptive equalization in a data transceiver including a plurality of adaptive filters wherein the adaptive filters are adapted with a first type of adaptation method to obtain initial convergence of the adaptive filters during an initial activation of the data transceiver and a second type of adaptation method to optimize performance of recovering the received signals in the presence of noise.

Activation method in data transceivers

A timing recovery circuit is disclosed that prevents phase error over-compensation. The timing recovery circuit includes a phase scanner for determining when phase error over-compensation has occurred and generating a signal for preventing dual phase compensation in response thereto thereby providing an accurate recovered clock signal. The timing recovery circuit also includes a feed-forward equalizer having a plurality of taps providing coefficients for filtering and adapting the input timing recovery circuit to an input signal. The phase scanner compares the tap coefficients to generate signal for preventing phase over-compensation by the feed-forward equalizer. A phase detector is provided for sampling coefficients from the feed-forward equalizer, error signals and output data and generating a phase signal used to generating the recovered clock signal. The signal for preventing phase over-compensation is mixed with the phase signal to generate the recovered clock signal.

Apparatus and method for performing timing recovery

Adaptive equalization methods and adaptive equalizers used with precoded systems dominated by intersymbol interference (ISI) monitor the output of a DFE and compare it to a reference for updating a precoder in response to the comparison. To accomplish this, an adaptive equalizer includes a feed forward equalizer receiving a signal from a communication channel, the feed forward equalizer equalizing variations in pre-cursor intersymbol interference resulting from changes in characteristics of the channel and providing an output signal to an error correction decoder, a decision circuit, coupled to the feed forward equalizer, for generating error vectors in response to the output signal of the feed forward equalizer and a decision feedback equalizer, coupled to the decision circuit, the decision feedback equalizer monitoring the pre-cursor intersymbol interference of the channel, determining when the transmitter coefficients to the precoder warrant updating, and generating a signal indicating that an update to the transmitter coefficients to the precoder is warranted. The adaptive equalizer farther includes a comparison circuit, the comparison circuit receiving an output from the decision feedback equalizer and comparing the output from the decision feedback equalizer to a reference, the comparison circuit generating the signal indicating that an update to the transmitter coefficients to the precoder is warranted in response to the comparison.

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Rocklin, CA, United States of America

Stanley K Ling