Jeffrey H Gilbert

US Patent:

7039004, May 2, 2006

Filed:

Oct 1, 2002

Appl. No.:

10/263415

Inventors:

Qinfang Sun - Cupertino CA, US
Won-Joon Choi - San Jose CA, US
Jeffrey M. Gilbert - Sunnyvale CA, US
Ning Zhang - Milpitas CA, US
Yi-Hsiu Wang - Palo Alto CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

H04J 11/00

US Classification:

370208, 370343, 375232, 375340

Abstract:

Current OFDM systems use a limited number of symbols and/or sub-channels to provide approximations for channel estimations and pilot tracking, i. e. phase estimations. For example, two training symbols in the preamble of a data packet are used to provide channel estimation. Four of the fifty-four sub-channels are reserved for providing phase estimation. However, noise and other imperfections can cause errors in both of these estimations, thereby degrading system performance. Advantageously, decision feedback mechanisms can be provided to significantly improve channel estimation and pilot tracking in OFDM systems. The decision feedback mechanisms can use data symbols in the data packet to improve channel estimation as well as data sub-channels to improve pilot tracking.

US Patent:

7088787, Aug 8, 2006

Filed:

Sep 24, 2001

Appl. No.:

09/962912

Inventors:

Jeffrey M. Gilbert - Sunnyvale CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

H03K 9/00
H04L 27/06
H04L 27/14
H04L 27/22

US Classification:

375316, 375344, 370210

Abstract:

A method of scaling at a receiver representations of training signals received from a transmitter. The method includes producing a frequency domain representation of at least one long training symbol received at the receiver and a frequency domain representation of a data symbol, and scaling the frequency domain representation of the at least one long symbol based on a largest coefficient in the frequency domain representation to produce a scaled frequency domain representation of the at least one long symbol.

US Patent:

7113559, Sep 26, 2006

Filed:

Sep 24, 2001

Appl. No.:

09/962842

Inventors:

Bevan M. Baas - Mountain View CA, US
Jeffrey M. Gilbert - Sunnyvale CA, US
William J. McFarland - Los Altos CA, US
Teresa H. Meng - Portola Valley CA, US
Ardavan Maleki Tehrani - Los Altos CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

H04B 1/10

US Classification:

375350, 375229, 375285, 708300

Abstract:

A circular filtering system that prevents the problem of inter-symbol interference. The circular filtering system utilizes a buffer memory to store samples of a given symbol and provide only these samples to a linear filter such that the output of the filter, for any given symbol is formed by filtering only samples of that input symbol. Each symbol being filtered independent of other symbols hence eliminating inter-symbol interference caused by filtering. Where symbols are tolerant to a fixed phase shift for each symbol, the circular filtering system can be simplified by reducing the size of the buffer and introducing a multiplexer.

US Patent:

7123670, Oct 17, 2006

Filed:

Sep 24, 2001

Appl. No.:

09/963115

Inventors:

Jeffrey M. Gilbert - Sunnyvale CA, US
Teresa H. Meng - Portola Valley CA, US
John Thomson - Santa Clara CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

H04L 27/06

US Classification:

375344, 4551922

Abstract:

A method for correcting influence of frequency offset between a receiver and a transmitter by evaluating training symbols received during a preamble period. The method includes producing, based on at least one long training symbol, a first vector whose first vector angle is indicative of a fine offset between the receiver and the transmitter, producing a fine offset estimate based on the first vector angle, and multiplying, with a signal having a frequency based upon the fine offset estimate, data symbols that are received after the at least one long training symbol is received.

US Patent:

7129884, Oct 31, 2006

Filed:

Jul 1, 2004

Appl. No.:

10/884785

Inventors:

Ardavan Maleki Tehrani - Menlo Park CA, US
Xiaoru Zhang - Sunnyvale CA, US
Paul J. Husted - San Jose CA, US
Jeffrey M. Gilbert - Sunnyvale CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

G01S 7/40
G01S 7/285
G01S 7/35
G01S 13/00

US Classification:

342 20, 342 13, 342 52, 342 58, 342 89, 342175, 342195

Abstract:

A radar detection technique in a WLAN device can include a short pulse detection technique and a long pulse detection technique that can be performed using multiple receive chains. Short pulse detection is particularly effective when the incoming signal includes one or a limited number of main pulses and some residual pulses. In contrast, long pulse detection is particularly effective when the incoming signal is longer, thereby allowing various characteristics of the incoming signal to be accurately measured.

US Patent:

7173972, Feb 6, 2007

Filed:

Mar 23, 2001

Appl. No.:

09/816810

Inventors:

John S. Thomson - Santa Clara CA, US
Paul J. Hustad - El Cerrito CA, US
Ardavan M. Tehrani - Menlo Park CA, US
Jeffrey M. Gilbert - Sunnyvale CA, US
William J. McFarland - Los Altos CA, US
Lars E. Thon - San Jose CA, US
Yi-Hsiu Wang - Palo Alto CA, US

International Classification:

H04K 1/10
H04L 27/28

US Classification:

375260, 375262, 375265, 375341, 714792, 714794, 714795

Abstract:

A Viterbi decoding system interprets bits in received QAM constellations as many-valued parameters rather than binary valued parameters. It performs the Viterbi algorithm using these many-valued parameters to provide results superior to hard decision decoding. Rather than applying a hard 0-1 function to the QAM data, the system uses a non-stepped linear or curved transfer function to assign values to the bits. In another aspect, a system differentiates between data bits based on their estimated reliability, giving more emphasis to decoding reliable bits than unreliable bits using any of a variety of techniques. By differentiating between god and bad bits and de-emphasizing or ignoring unreliable bits, the system can provide a significant reduction in uncorrectable errors and packet loss.

US Patent:

7321631, Jan 22, 2008

Filed:

Jul 31, 2006

Appl. No.:

11/461347

Inventors:

Won-Joon Choi - Santa Clara CA, US
Jeffrey M. Gilbert - Santa Clara CA, US
Yi-Hsiu Wang - Santa Clara CA, US
Xiaoru Zhang - Santa Clara CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

H03D 1/00
H04K 1/10

US Classification:

375260, 375341, 375346

Abstract:

Spurs cause significant problems with signal detecting, amplifier gain adjustment, and signal decoding. Various techniques can be used to mitigate the effects of spurs on a received signal. Generally, these techniques work by either canceling or ignoring the spurs. For example, a pilot mask can be used to ignore pilot information in one or more sub-channels. A Viterbi mask can determine the weighting given to bits in a sub-channel based on spur and data rate information. Channel interpolation can compute a pseudo channel estimate for a sub-channel known to have a spur location can be computed by interpolating the channel estimates of adjacent good sub-channels. Filtering of the received signal using a low-pass filter, a growing box filter, or a low-pass filter with self-correlation can be used to cancel a spur.

US Patent:

7366089, Apr 29, 2008

Filed:

Oct 8, 2003

Appl. No.:

10/682787

Inventors:

Ardavan M. Tehrani - Menlo Park CA, US
Won-Joon Choi - Sunnyvale CA, US
Jeffrey M. Gilbert - Sunnyvale CA, US
Yi Hsiu Wang - Menlo Park CA, US

Assignee:

Atheros Communications, Inc. - Santa Clara CA

International Classification:

H04L 5/04

US Classification:

370208, 370210, 375347

Abstract:

The present invention provides an apparatus and method of multiple antenna receiver combining of high data rate wideband packetized wireless communication signals, where the apparatus includes M receive antennas, receiving M high data rate wideband packetized wireless communication signals, where each of the signals includes N frequency bins. The apparatus, in an exemplary embodiment, includes (1) a joint timing recovery units that perform joint coarse signal timing estimation, joint frequency offset estimation, and joint fine timing estimation on each of the signals, (2) M Fast Fourier Transform units (FFTs) that each convert the digital data for each of the M signals into frequency domain information for each of the N received frequencies and that output Q pilots for each of the signals, where Q is a positive integer, and (3) a combiner that weights and combines the outputs of the M FFTs for each of the N received frequencies.