Seong Taek Chung

US Patent:

7593426, Sep 22, 2009

Filed:

May 10, 2004

Appl. No.:

10/842710

Inventors:

Jungwon Lee - Stanford CA, US
John M. Cioffi - Atherton CA, US
Seong Taek Chung - San Diego CA, US

Assignee:

The Board of Trustees of the Leland Stanford Junior University - Palo Alto CA

International Classification:

H04J 3/16
H04J 3/00

US Classification:

370468, 370464

Abstract:

Approaches to operating a multi-user, multi-carrier communication system involve allocating a target bit rate across user channels and subchannels to adjust the power. The target bit rate is allocated among subchannels of the user channels as a function of system power associated with the subchannel bit rate allocation. The target bit is allocated among user channels of the communication system as a function of system power associated with the user bit rate allocation. The power allocation for each user channel is determined based on the bit rate allocation.

US Patent:

7630451, Dec 8, 2009

Filed:

Jan 11, 2006

Appl. No.:

11/330796

Inventors:

Bruce Collins - San Diego CA, US
Rajeev Krishnamurthi - San Diego CA, US
Murali Ramaswamy Chari - San Diego CA, US
Shusheel Gautam - San Diego CA, US
Rajiv Vijayan - San Diego CA, US
Seong Taek Chung - Redwood City CA, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H04L 5/12

US Classification:

375261, 375298, 455 60

Abstract:

A media access control (MAC) layer controller can manage base layer data and enhancement layer data in a layered modulation system. The MAC layer controller can process both base layer data and enhancement layer data and map the encoded symbols to a layered modulation constellation when both are present. If data for one of the layers terminates, then the MAC layer controller can generate and supply predetermined stuffing data to the layer lacking additional data. The MAC layer controller can send a control signal to the physical layer hardware to cause the hardware to map the layered signals having the stuffing data to a modified signal constellation. The MAC controller can also generate an overhead message that indicates the occurrence of the stuffing data. The receiver can receive the overhead message and can use the information to configure the receiver for the layered modulation constellation or the modified signal constellation.

US Patent:

7660368, Feb 9, 2010

Filed:

Jan 11, 2006

Appl. No.:

11/330652

Inventors:

Fuyun Ling - San Diego CA, US
Seong Taek Chung - Redwood City CA, US
Jinxia Bai - San Diego CA, US
Thomas Sun - San Diego CA, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H03D 3/22

US Classification:

375332, 341143, 370207, 375262, 375265, 375341

Abstract:

A system and method are provided for generating bit log likelihood ratio (LLR) values for two-layered Quadrature Phase-Shift Keying (QPSK) turbo decoding in a wireless communications user terminal (UT). The method includes receiving a two-layered QPSK signal with an energy ratio that is unknown, but typically defined as either kor k. The method selects a mismatched energy ratio (k) between kand k, and generating bit LLR values for two-layered QPSK turbo decoding, using the mismatched kenergy ratio. For example, if the received two-layered QPSK signal is known to have an energy ratio of about 4 or about 6. 25. Then, kis selected to be about 5. 0625. Alternately stated, the mismatched kenergy ratio in selected by determining the approximate midpoint between kand k.

US Patent:

7725799, May 25, 2010

Filed:

Mar 31, 2005

Appl. No.:

11/096320

Inventors:

Gordon Kent Walker - Poway CA, US
Rajiv Vijayan - San Diego CA, US
Seong Taek Chung - Redwood City CA, US
Murali Ramaswamy Chari - San Diego CA, US
Fuyun Ling - San Diego CA, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H03M 13/00
H03M 13/03

US Classification:

714755, 714774

Abstract:

A wireless communication apparatus in a hierarchically coded modulation system can use error control mechanisms generated during decoding of base layer information to predict a probability of successful demodulation of enhancement layer information. Performance in the demodulation of the base layer correlates to performance in the demodulation of the enhancement layer. The receiver can determine whether to attempt demodulation of temporally correlated enhancement layer data based in part on the predicted probability of success. If the receiver determines not to demodulate the enhancement layer, the receiver can power down the enhancement layer demodulator, or otherwise minimize the power expended in the enhancement layer demodulator.

US Patent:

7746963, Jun 29, 2010

Filed:

Nov 8, 2006

Appl. No.:

11/557921

Inventors:

Seong Taek Chung - Redwood City CA, US
Krishna Kiran Mukkavilli - San Diego CA, US
Vinay Murthy - San Diego CA, US
Tao Tian - San Diego CA, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H04L 27/00

US Classification:

375344, 375260, 375326

Abstract:

Methods and apparatus for frequency tracking of a received signal. In an aspect, a method is provided wherein the received signal comprises one or more symbols having a periodic structure. The method comprises receiving a plurality of samples of a selected symbol that comprises pilot signals scrambled with data and determining a window size and a periodicity factor. The method also comprises accumulating a correlation between samples in a first window and samples in a second window to produce an accumulated correlation value, wherein the first and second windows have a size and a separation based on the window size and the periodicity factor, respectively, and deriving a frequency error estimate based on the accumulated correlation value.

US Patent:

7830955, Nov 9, 2010

Filed:

Jul 8, 2006

Appl. No.:

11/995195

Inventors:

John M. Cioffi - Atherton CA, US
Wonjong Rhee - San Francisco CA, US
Georgios Ginis - San Mateo CA, US
Seong Taek Chung - Redwood City CA, US

Assignee:

Adaptive Spectrum & Signal Alignment, Inc. - Redwood City CA

International Classification:

H04B 1/38

US Classification:

375222

Abstract:

Configuration or otherwise controlling parameters of a Digital Subscriber Line (DSL) system related to power, band usage and margin is based on collected operational data. Operational data are collected from at least one DSL system operating under a known configuration and/or a profile. A target profile is selected based on binder-level information. The collected operational data is analyzed and conditions for changing the DSL system configuration to the target profile are evaluated, including any applicable transition rules pertaining to changing profiles. If the conditions hold, then the DSL system is instructed to operate with the target profile. Binder-level information can include deployment point information, topology information, and/or crosstalk coupling information. The controlled parameters may have values that are chosen using one or more spectrum balancing methods. Such spectrum balancing methods may be executed infrequently, and may make use of all binder-level information that is available.

US Patent:

7924736, Apr 12, 2011

Filed:

Jul 8, 2006

Appl. No.:

11/995194

Inventors:

John M. Cioffi - Atherton CA, US
Wonjong Rhee - San Francisco CA, US
Bin Lee - Palo Alto CA, US
Seong Taek Chung - Redwood City CA, US
Georgios Ginis - San Mateo CA, US

Assignee:

Adaptive Spectrum and Signal Alignment, Inc. - Redwood City CA

International Classification:

H04L 12/26

US Classification:

370252, 370241, 375224, 379 103, 379 12, 379 3204

Abstract:

Estimates of a communication system configuration, such as a DSL system, are based on operational data collected from a network element management system, protocol and users. The operational data collected from the system can include performance-characterizing operational data that typically is available in the OSL system via element-management-system protocols. Generated estimates and/or approximations can be used in evaluating system performance and directly or indirectly dictating/requiring changes or recommending improvements in operation by transmitters and/or other parts of the indication system. Data and/or other information may be collected using internal means or using system elements and components via e-mail and/or other extra means. The likelihood of the models accuracy can be based on various data, information and/or indicators of system performance, such as observed normal operational data, test data and/or prompted operational data that shows operating performance based on stimulation signals.

US Patent:

8009775, Aug 30, 2011

Filed:

Mar 9, 2006

Appl. No.:

11/372931

Inventors:

Vinay Murthy - San Diego CA, US
Alok Kumar Gupta - Encinitas CA, US
Seong Taek Chung - Redwood City CA, US
Fuyun Ling - San Diego CA, US

Assignee:

QUALCOMM Incorporated - San Diego CA

International Classification:

H04L 27/06
H04L 7/00
H04L 27/00

US Classification:

375344, 375354, 375324, 375326

Abstract:

Techniques for performing frequency control in an OFDM system are described. In one aspect, frequency acquisition is performed based on a received pilot, and frequency tracking is performed based on received OFDM symbols. For frequency acquisition, an initial frequency error estimate may be derived based on the received pilot, and an automatic frequency control (AFC) loop may be initialized with the initial frequency error estimate. For frequency tracking, a frequency error estimate may be derived for each received OFDM symbol, and the AFC loop may be updated with the frequency error estimate. Frequency error in input samples is corrected by the AFC loop with the initial frequency error estimate as well as the frequency error estimate for each received OFDM symbol. In another aspect, a variable number of samples of a received OFDM symbol are selected, e. g. , based on the received OFDM symbol timing, for use for frequency error estimation.