Leland Stanford Junior University

Atheros Communications, Inc.

Amicus Wireless Technology Ltd

Qualcomm Atheros Inc.

Amicos Wireless Technology Ltd.

The Connectivity Patent Trust

Chaohuang Zeng

John Matthew Cioffi

Wei Yu

Georgios Ginis

William John McFarland

Won-Joon Choi

Kee-Bong Song

Jeffrey M Gilbert

Xiaoru Zhang

Deepak Dhamdhere

Gwang-Hyun Gho

Carlos Aldana

Jingnong Yang

Atul Salvekar

William Mcfarland

Control of a digital communication system having a plurality of communication lines on which signals are transmitted and received is implemented using a variety of methods and systems. According to one embodiment of the present invention, a method is implemented where the signals are affected by interference during transmission and each of the communication lines has at least one transmitter and at least one receiver. A model is created of the interference characteristics due to the signals carried on the communication lines. Interference characteristics for a line are determined based on the model and actual signals carried on other communication lines different from the line for which the characteristics are being determined. Actual interference is compensated for on the communication line using the determined interference characteristics.

Dynamic digital communication system control

Techniques are disclosed for detecting a packet. One technique includes sampling a received signal to produce a sequence of samples wherein the sequence of samples includes a plurality of subsequences of samples; cross correlating the subsequences of samples with a known form of the subsequence to produce cross correlations; self correlating the cross correlations to produce a plurality of self correlations; summing the self correlations; and processing the sum of the self correlations.

Packet detection, synchronization, and frequency offset estimation

Methods, apparatus and systems for dynamically controlling a digital communication system, such as a DSL system, collect information about digital communication lines in the system and adaptively and/or dynamically determine line and signal characteristics of the digital communication lines, including interference effects. Based on the determined characteristics and the desired performance parameters, operation of the digital communication lines is adjusted to improve or otherwise control the performance of the system. The collection and processing of information may be performed by a party that is not a user in the system. This independent party also may control operational characteristics and parameters of the system. The invention can be used to eliminated or reduce signal interference such as crosstalk that can be induced on communication lines in systems such as DSL systems. Specific iterative power allocation and vectored transmission techniques and apparatus are disclosed.

A data packet, comprising a preamble and the preamble comprising a plurality of synchronization bits, is received where the preamble may be of either a first preamble type or a second preamble type. Channel estimation is performed using at least a first portion of the plurality of synchronization bits. It is determined whether the preamble is of the first preamble type or of the second preamble type, where the determination overlaps in least in part with the channel estimation. The performance of the channel estimation is controlled such that: in the event it is determined the preamble is of the first preamble type, the performance of the channel estimation continues for a second portion of the plurality of synchronization bits, adjacent to the first portion of the plurality of synchronization bits, after the processing of the first portion of the plurality of synchronization bits; in the event it is determined the preamble is of the second preamble type, the performance of the channel estimation ends after processing the first portion of the plurality of synchronization bits.

Dynamic preamble detection

An Orthogonal Frequency Division Multiple Access (OFDMA) device and method of correcting frequency offset in OFDMA signals computes an estimated frequency offset, which is used for producing a frequency offset-compensated mixer signal using a reference clock signal. The frequency offset-compensated mixer signal is used to produce a digital down-converted signal from an incoming OFDMA signal. The digital down-converted signal is digitally corrected for sampling errors using the estimated frequency offset.

OFDMA device and method of correcting frequency offset in OFDMA signals

A decoder and method for decoding a tail-biting convolutional encoded signal using Viterbi decoding scheme performs a traceback operation for a first portion of a total code block, which includes a code block of the tail-biting convolutional encoded signal and a padded block. During the traceback operation for the first portion, a particular state at a predefined position within the first portion is stored as a circular state. The circular state is used as a traceback starting state for at least one subsequent portion of the total code block to produce a decoded signal of the code block.

Decoder and method for decoding a tail-biting convolutional encoded signal using Viterbi decoding scheme

A device and method for performing channel estimation for an OFDM-based wireless communication system modifies pilot subcarrier spacing to use a set of interpolation coefficients associated with a different pilot subcarrier spacing.

Device and method for performing channel estimation for OFDM-based signals with variable pilot subcarrier spacing

A device and method of performing channel estimation for an OFDM-based wireless communication system performs a Least Square interpolation with a statistical channel profile consideration on pilot channel estimates to derive data channel estimates at data subcarrier locations.

Device and method of performing channel estimation for OFDM-based wireless communication system

A modified approach to detecting the start frame delimiter (SFD) is disclosed. A receiving system scans a decoded but not yet de-scrambled received signal for a scrambled version of the SFD associated with the preamble format being used. Using this approach, it is not necessary to use any bits intended for use in synchronization to initialize a de-scrambler so as to be able to de-scramble the SFD portion of the preamble for detection. The bits that otherwise would have been dedicated to initializing the de-scrambler may then be used for synchronization, as intended. Detecting fewer than all bits comprising a start frame delimiter is described. Bits not used for SFD detection may be used for other purposes, such as synchronization.

Modified start frame delimiter detection

A system and method are disclosed for dynamic preamble detection. A subset of the bits comprising the synchronization portion of the preamble are decoded, de-scrambled, and analyzed to determine dynamically which preamble format is being used. The source data values for the synchronization bits for a first preamble format are different than the source data values for the synchronization bits for a second preamble format and the receiving system uses the difference to determine which preamble format has been used. The information concerning which format has been used may be used to extend a synchronization operation.

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Chaohuang Zeng