Patents by Inventor Yang-Seok Choi

Yang-Seok Choi has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Publication number: 20110002279
    Abstract: Embodiments of the present invention provide an uplink open loop power control system in which interference over thermal information is transmitted to mobile stations. Other embodiments may be described and claimed.
    Type: Application
    Filed: December 15, 2009
    Publication date: January 6, 2011
    Inventors: Rongzhen Yang, Wei Guan, Apostolos Papathanassiou, Hujun Yin, Yang-Seok Choi, Yi Hsuan
  • Patent number: 7844240
    Abstract: A method of performing receive antenna selection is presented. The method executes a determination operation for a set of receive antennas, determines a maximum result of the determination operation for two of the antennas, eliminates one of the two antennas from the set of antennas, and repeats the determination and elimination process until only a predetermined number of antennas remain in the set. The signals from these remaining antennas are then processed. The present invention reduces receiver complexity and cost.
    Type: Grant
    Filed: August 30, 2007
    Date of Patent: November 30, 2010
    Assignee: AT&T Intellectual Property II, L.P.
    Inventors: Jack Harriman Winters, Yang-Seok Choi, Byoung-Jo J Kim, Andreas Molisch, Moe Z. Win, Hui Luo
  • Publication number: 20100254472
    Abstract: An embodiment of the present invention provides a space-time block code (STBC) transmission method for 4 transmit antennas, comprising adding two 2×2 orthogonal pre-coding before a two Alamouti transmission for a 4 transmit antennas scheme.
    Type: Application
    Filed: April 6, 2009
    Publication date: October 7, 2010
    Inventors: Jiacheng Wang, Hujun Yin, Yang-seok Choi, Liang Jiang
  • Publication number: 20100254433
    Abstract: A symbol structure is disclosed for use at least with wireless signal transmitters. The symbol structure includes a symbol that is spread over at least two symbol time periods. The symbol may include at least two replicas of the same code. The subcarrier spacing of subcarriers of the symbol has a p/q ratio of the subcarrier spacing of an IEEE 802.16e symbol. In some cases, the symbol includes interspersed null values. The decoding of the symbol involves performing a Fourier transform on the symbol.
    Type: Application
    Filed: April 6, 2009
    Publication date: October 7, 2010
    Inventors: Shahrnaz Azizi, Yang-Seok Choi, Shailender Timiri, Xinrong Wang
  • Patent number: 7801084
    Abstract: A technique for Doppler frequency estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. A frequency domain approach may be applied to any OFDM because it utilizes pilot subcarriers, and thus does not increase the system overhead. An estimator may be implemented as a relatively low-complexity finite impulse response (FIR) filter bank with coefficients that may be pre-calculated and stored in memory.
    Type: Grant
    Filed: June 9, 2006
    Date of Patent: September 21, 2010
    Assignee: Intel Corporation
    Inventors: Yang-Seok Choi, Siavash Alamouti
  • Patent number: 7801231
    Abstract: Techniques are disclosed involving preamble sequences. For instance, an apparatus includes a module to provide a preamble sequence having multiple values, where each of the values corresponds to an orthogonal frequency division multiplexing (OFDM) subcarrier. These multiple values may include multiple blocks of values based on a differentially encoded and scrambled row of a Hadamard matrix. The apparatus may further include a modulation module to produce an OFDM modulated signal from the preamble sequence. Further, techniques for the detection of such preambles are disclosed.
    Type: Grant
    Filed: September 27, 2007
    Date of Patent: September 21, 2010
    Assignee: Intel Corporation
    Inventors: Vahid Tarokh, Shahrnaz Azizi, Yang-seok Choi
  • Publication number: 20100226322
    Abstract: Embodiments of an apparatus and methods for transmission of timing and synchronization information for mobile WiMAX systems are generally described herein. Other embodiments may be described and claimed.
    Type: Application
    Filed: February 24, 2010
    Publication date: September 9, 2010
    Inventors: Yang-Seok Choi, Ahmed Ibrahim, Jiachen Wang
  • Publication number: 20100166119
    Abstract: Embodiments of MIMO symbol decoders and methods for decoding spatially multiplexed symbols using combined linear equalization decoding and maximum likelihood decoding are generally described herein. In some embodiments, one group of symbols (y) received through two or more spatial channels is decoded using a linear equalization decoding technique and another group of symbols is decoded using a maximum likelihood decoding (MLD) technique to generate a soft-bit output. The symbols may be grouped for either linear equalization decoding or MLD based on channel orthogonality or signal-to-interference and noise ratios (SINRs).
    Type: Application
    Filed: December 30, 2008
    Publication date: July 1, 2010
    Inventors: Jiacheng Wang, Hujun Yin, Yang-Seok Choi, Liang Jiang
  • Publication number: 20100157906
    Abstract: Techniques are disclosed that provide for femto base stations to become synchronized with other base stations in a wireless network. For instance, a macro base station may instruct a mobile station to engage in a synchronization operation that synchronizes one or more timings (e.g., OFDM timings) of a femto base station with one or more corresponding timings of the macro base station. This may involve the mobile station having timing references of the macro base station. Further, this may involve the mobile station performing scanning operations and/or handover ranging operations with the femto base station. The mobile device may determine timing offsets between the femto BS and the macro BS. These offsets may be sent to the macro base station or to the femto base station. Also, the femto base station may adopt timings employed by the mobile station.
    Type: Application
    Filed: December 21, 2009
    Publication date: June 24, 2010
    Inventors: Xiangying Yang, Muthaiah Muthu Venkatachalam, Yang-Seok Choi
  • Patent number: 7720166
    Abstract: Embodiments of the present invention provide a method, apparatus and system of decoding spatially multiplexed signals. In some demonstrative embodiments the method may include, for example, determining one or more hypothetical values of a transmitted signal of a set of transmitted signals based on one or more respective sets of hypothetical values assigned to a subset of the set of transmitted signals. Other embodiments are described and claimed.
    Type: Grant
    Filed: March 30, 2006
    Date of Patent: May 18, 2010
    Assignee: Intel Corporation
    Inventors: Yuval Lomnitz, Yang-Seok Choi
  • Publication number: 20100080113
    Abstract: Embodiments of the present disclosure describe closed loop scheduled peak-to-average power (PAPR) reduction systems and methods to facilitate desired PAPR reduction. Other embodiments describe weighted tone reservation (WTR) methods and systems for PAPR reduction. Still other embodiments may be described and claimed.
    Type: Application
    Filed: September 30, 2008
    Publication date: April 1, 2010
    Inventors: Rongzhen Yang, Hujun Yin, Yang-Seok Choi, Linging Gui
  • Publication number: 20100080308
    Abstract: Embodiments of the present invention provide a virtual multicarrier design for orthogonal frequency division multiple access communications. Other embodiments may be described and claimed.
    Type: Application
    Filed: September 30, 2008
    Publication date: April 1, 2010
    Inventors: Hujun Yin, Rongzhen Yang, Xiaoshu Qian, Yang-Seok Choi, Sassan Ahmadi, Kamran Etemad
  • Publication number: 20100064185
    Abstract: A PHY abstraction mapping between the link level and system level performance is presented based on mapping between the mean RBIR (Received Bit Information Rate) of the transmitted symbols and their received LLR values after symbol-level ML detection in SISO/MIMO wireless systems, such as WiMAX. In MIMO antenna configuration, the mapping is presented for both vertical and horizontal encoding. An embodiment of this invention provides the PER/BLER prediction in the actual system, enabling the system to use more aggressive methods to improve the system performance.
    Type: Application
    Filed: September 10, 2008
    Publication date: March 11, 2010
    Inventors: Hongming Zheng, Wu Mav, Yang-seok Choi, Senjie Zhang
  • Publication number: 20090274105
    Abstract: Short spreading is used within a random access channel in an OFDM based network to spread data for transmission through the channel. The resource allocation of the random access channel is divided into a number of resource blocks in frequency, time, or both frequency and time. Each resource block has a dimension that is only a portion of the overall size of the resource allocation. During contention, a randomly selected short spreading code may be used to provide data spreading within a randomly selected resource block.
    Type: Application
    Filed: May 2, 2008
    Publication date: November 5, 2009
    Inventors: Yang-Seok Choi, Muthaiah Venkatachalam, Xiangying Yang, Apostolos Papathanassiou
  • Publication number: 20090175366
    Abstract: An apparatus, system, and method for space-time cochannel interference cancellation are described. The apparatus may include a time stacking module to stack consecutive subcarrier signals for a period of time equal to several symbols and a space-time subcarrier beamformer module to perform space-time subcarrier beamforming by applying space-time beamformer weights to stacked symbols on one or more subcarriers. The space-time beamformer weights may be calculated based on spatial and time correlation properties of one or more interference signals. Other embodiments are described and claimed.
    Type: Application
    Filed: September 30, 2005
    Publication date: July 9, 2009
    Inventors: Alexander Maltsev, Alexey Khoryaev, Roman Maslennikov, Vladimir Pestretsov, Qinghua Li, Yang-seok Choi
  • Publication number: 20090086832
    Abstract: Techniques are disclosed involving preamble sequences. For instance, an apparatus includes a module to provide a preamble sequence having multiple values, where each of the values corresponds to an orthogonal frequency division multiplexing (OFDM) subcarrier. These multiple values may include multiple blocks of values based on a differentially encoded and scrambled row of a Hadamard matrix. The apparatus may further include a modulation module to produce an OFDM modulated signal from the preamble sequence. Further, techniques for the detection of such preambles are disclosed.
    Type: Application
    Filed: September 27, 2007
    Publication date: April 2, 2009
    Inventors: Vahid Tarokh, Shahrnaz Azizi, Yang-seok Choi
  • Publication number: 20080159203
    Abstract: Methods and apparatus are described herein to provide for wireless communications mode switching in a MIMO communications system. Other embodiments may include a method for communicating through a MIMO channel that includes choosing a communications level for each of at least two communications mode, and calculating the spectral efficiency for the chosen communications level. The method may further include comparing the spectral efficiencies and choosing a communications mode and communications level based on the comparison. Further embodiments may include a communications apparatus that includes a transceiver, a capacity calculator and a selecting module. Other embodiments are described and claimed.
    Type: Application
    Filed: December 29, 2006
    Publication date: July 3, 2008
    Inventors: Yang-Seok Choi, Siavash M. Alamouti
  • Publication number: 20070286298
    Abstract: A technique for Doppler frequency estimation in Orthogonal Frequency Division Multiplexing (OFDM) systems. A frequency domain approach may be applied to any OFDM because it utilizes pilot subcarriers, and thus does not increase the system overhead. An estimator may be implemented as a relatively low-complexity finite impulse response (FIR) filter bank with coefficients that may be pre-calculated and stored in memory.
    Type: Application
    Filed: June 9, 2006
    Publication date: December 13, 2007
    Inventors: Yang-Seok Choi, Siavash Alamouti
  • Patent number: 7283798
    Abstract: A method of performing receive antenna selection is presented. The method executes a determination operation for a set of receive antennas, determines a maximum result of the determination operation for two of the antennas, eliminates one of the two antennas from the set of antennas, and repeats the determination and elimination process until only a predetermined number of antennas remain in the set. The signals from these remaining antennas are then processed. The present invention reduces receiver complexity and cost.
    Type: Grant
    Filed: December 29, 2005
    Date of Patent: October 16, 2007
    Assignee: AT&T Corp.
    Inventors: Jack Harriman Winters, Yang-Seok Choi, Byoung-Jo J Kim, Andreas Molisch, Moe Z. Win, Hui Luo
  • Publication number: 20070230631
    Abstract: Embodiments of the present invention provide a method, apparatus and system of decoding spatially multiplexed signals. In some demonstrative embodiments the method may include, for example, determining one or more hypothetical values of a transmitted signal of a set of transmitted signals based on one or more respective sets of hypothetical values assigned to a subset of the set of transmitted signals.
    Type: Application
    Filed: March 30, 2006
    Publication date: October 4, 2007
    Inventors: Yuval Lomnitz, Yang-Seok Choi