Patents by Inventor Inwoong Kim

Inwoong Kim 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: 20210167736
    Abstract: In accordance with an aspect of the present disclosure, there is provided a power amplification apparatus, the apparatus comprising: an input part; a first-1 transformer and a first-2 transformer connected to the input part in parallel; a first amplifier and a second amplifier connected to the first-1 transformer and the first-2 transformer, respectively; a first switch connected to one side of the first-2 transformer; a second-1 transformer and a second-2 transformer connected to the first amplifier and the second amplifier, respectively, and connected to an output part in parallel; and a second switch connected to one side of the second-2 transformer.
    Type: Application
    Filed: November 27, 2020
    Publication date: June 3, 2021
    Inventors: Taehoon Kim, Jaedon Park, Jungho Joe, Youngsin Kim, Jongsung Park, Inwoong Kang, Sanggeun Jeon, Seungwon Park
  • Patent number: 11012187
    Abstract: An optical transmitter for probabilistic shaping and symbol rate optimization includes one or more matcher elements, each configured to assign respective probabilities to symbols represented in received binary data dependent on a target probability distribution and to output a respective shaped bit sequence. The optical transmitter further includes a single systematic error correction encoder configured to add parity bits collectively across the shaped bit sequences and to output a combined shaped bit sequence including data representing the shaped bit sequences and the added parity bits. The optical transmitter also includes multiple mapping elements, each configured to generate a respective codeword for each symbol represented in a portion of the combined shaped bit sequence, a serial-to-parallel converter to provide portions of the combined shaped bit sequence to the mapping elements, and a multiplexer to combine binary data representing the codewords for transmission using subcarrier multiplexing.
    Type: Grant
    Filed: March 4, 2020
    Date of Patent: May 18, 2021
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Olga I. Vassilieva, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10700807
    Abstract: Systems and methods for setting fiber input power for an optical transmission path may include determining an initial modulation format representing a uniform distribution QAM format, the initial modulation format associated with a first fiber input power and a first spectral efficiency, configuring optical transponders to apply probabilistic shaping to the initial modulation format when transmitting traffic over the optical transmission path, the traffic including probabilistically shaped signals with a second spectral efficiency, determining, dependent on the second spectral efficiency, a second fiber input power, and configuring optical amplifiers along the optical transmission path to transmit the traffic comprising the probabilistically shaped signals over the optical transmission path using the second fiber input power.
    Type: Grant
    Filed: July 1, 2019
    Date of Patent: June 30, 2020
    Assignee: Fujitsu Limited
    Inventors: Olga I. Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Patent number: 10601517
    Abstract: A system and method for probabilistic shaping of an eight-dimensional super-symbol in optical transport networks, including receiving binary data to be transmitted as an optical signal; mapping at least a portion of the binary data to symbols of a M-QAM constellation; generating a first four-dimensional symbol of the M-QAM constellation for a first symbol period, including applying probabilistic shaping to the first four-dimensional symbol; generating a second four-dimensional symbol of the M-QAM constellation for a second symbol period, the second symbol period consecutive to the first symbol period, wherein the first and the second four-dimensional symbols have i) an equal symbol energy and ii) a one-to-one relationship; and time interleaving the first symbol period and the second symbol period to generate an eight-dimensional super-symbol.
    Type: Grant
    Filed: January 22, 2019
    Date of Patent: March 24, 2020
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Sebastiaan Anne René Goossens, Olga I. Vassilieva, Tadashi Ikeuchi
  • Patent number: 10530490
    Abstract: Systems and methods for constellation shaping of QAM modulation formats in an optical transport network may include selecting a target information rate for an optical transmission path, determining a measure of fiber nonlinearity for transmission media on the path, and selecting, dependent on the measure of fiber nonlinearity, one of multiple supported shaping parameter pairs, each specifying a respective shaping strength level and a respective error correction strength level. A network management system may configure optical transponders to apply probabilistic shaping to a QAM modulation format in accordance with the selected shaping parameter pair. A shaping parameter pair specifying a high shaping strength level and a low error correction strength level may be selected when the measure of fiber nonlinearity is high. A shaping parameter pair specifying a low shaping strength level and a high error correction strength level may be selected when the measure of fiber nonlinearity is low.
    Type: Grant
    Filed: February 27, 2019
    Date of Patent: January 7, 2020
    Assignee: Fujitsu Limited
    Inventors: Olga I. Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Patent number: 10511388
    Abstract: Systems and methods for reducing variance in reach of wavelength division multiplexed (WDM) channels in optical transport networks may include selecting, for each channel assigned to a respective wavelength, an initial modulation format and an initial distribution of constellation points in the complex plane, determining a target reach for all WDM channels that is achievable by higher wavelength channels but not by shorter wavelength channels, and applying one or more reach extension techniques to at least one shorter wavelength channel but not to the higher wavelength channels. The reach extension techniques may include probabilistic constellation shaping, symbol rate optimized subcarrier multiplexing, or a combination of the two. Transponders may be configurable to transmit or receive traffic over the WDM channels with or without implementing the reach extension techniques, as applicable.
    Type: Grant
    Filed: August 10, 2018
    Date of Patent: December 17, 2019
    Assignee: Fujitsu Limited
    Inventors: Olga I. Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Patent number: 10461881
    Abstract: Systems and methods for identifying a pair of nodes of a plurality of nodes of a virtual optical network (VON); identifying i) an optical route between the pair of nodes and ii) a desired availability of the optical route; determining a probability density function (PDF) of a signal-to-noise ratio (SNR) of a signal of the optical route; determining a SNR threshold such that an integration of the PDF of the SNR of the signal above the SNR threshold corresponds to the desired availability of the optical route; determining a plurality of spectral efficiencies that corresponds to the SNR threshold, each spectral efficiency of the plurality of spectral efficiencies associated with a respective modulation format of a plurality of modulation formats; and identifying a particular modulation format of the plurality of modulation formats that corresponds to a maximum spectral efficiency of the plurality of spectral efficiencies.
    Type: Grant
    Filed: October 8, 2018
    Date of Patent: October 29, 2019
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Xi Wang, Olga Vassilieva, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10396899
    Abstract: Systems and methods for constellation shaping of M-QAM modulation formats in optical transport networks may receive binary data to be transmitted as an optical signal and partition symbols of an M-QAM constellation in the complex plane into two non-overlapping subsets of symbols, The systems and methods may include assigning respective probabilities to each symbol in the first subset of symbols dependent on a target probability distribution for the first subset, mapping at least a portion of the received binary data to the symbols in the first subset, including generating a respective codeword for each symbol in the first subset, in a first symbol period, providing data representing the respective codewords mapped to the symbols in the first subset to an optical modulator for transmission, and refraining from providing any data representing codewords mapped to the symbols in the second subset to the optical modulator until a second symbol period.
    Type: Grant
    Filed: August 21, 2018
    Date of Patent: August 27, 2019
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Olga I. Vassilieva, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10389473
    Abstract: A disclosed method for extending reach in an adaptive optical network may include selecting, for an optical channel having a given target distance and a given maximum data rate, the modulation format having the highest spectral efficiency among modulation formats supported in the adaptive optical network that are suitable for optical channels having the given target distance and the given maximum data rate, determining a symbol rate for the optical channel dependent on characteristics of transmission media for the optical channel, determining a number of subcarriers for the optical channel corresponding to the determined symbol rate, and activating subcarrier multiplexing (SCM) for the optical channel. Activating SCM may include configuring transponders to transmit or receive the traffic in the optical channel using the selected modulation format and the determined number of subcarriers. The method may be implemented by a network management system of the optical network.
    Type: Grant
    Filed: April 27, 2018
    Date of Patent: August 20, 2019
    Assignee: Fujitsu Limited
    Inventors: Olga I. Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Patent number: 10355779
    Abstract: A method for VON service with guaranteed availability may use probability density functions (PDF) of Q-factor to determine availability of physical links assigned to a virtual link in the VON. Then, a VON mapping may be performed based on the determined availabilities, among other factors.
    Type: Grant
    Filed: September 25, 2017
    Date of Patent: July 16, 2019
    Assignee: FUJITSU LIMITED
    Inventors: Inwoong Kim, Xi Wang, Martin Bouda, Olga Vassilieva, Qiong Zhang, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10348439
    Abstract: A control system for spectral slot assignment in flexible grid optical networks determines, for a given optical path, a physical source node, a physical destination node, and physical intermediate nodes, determines the number of contiguous spectral slots to allocate for traffic on the path, identifies candidate combinations of spectral slots available for the traffic, and creates an auxiliary graph for the path. The auxiliary graph includes auxiliary links representing candidate combinations of spectral slots, virtual nodes representing pairs of neighboring physical nodes, and auxiliary links between each pair of virtual source-side and destination-side intermediate nodes representing either pass-through traffic or wavelength shifted traffic.
    Type: Grant
    Filed: May 14, 2018
    Date of Patent: July 9, 2019
    Assignee: Fujitsu Limited
    Inventors: Inwoong Kim, Xi Wang, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10256911
    Abstract: Methods and systems enable amplifying optical signals using a Bragg reflection waveguide (BRW) having second order optical nonlinearity to generate an optical pump by injection locking. The BRW may also be used for parametric amplification of optical signals using the optical pump. Feedback phase-power control may be performed to maximize output power.
    Type: Grant
    Filed: January 19, 2018
    Date of Patent: April 9, 2019
    Assignee: FUJITSU LIMITED
    Inventors: Inwoong Kim, Youichi Akasaka, Jeng-Yuan Yang, Motoyoshi Sekiya
  • Publication number: 20190097720
    Abstract: A method for VON service with guaranteed availability may use probability density functions (PDF) of Q-factor to determine availability of physical links assigned to a virtual link in the VON. Then, a VON mapping may be performed based on the determined availabilities, among other factors.
    Type: Application
    Filed: September 25, 2017
    Publication date: March 28, 2019
    Inventors: Inwoong Kim, Xi Wang, Martin Bouda, Olga Vassilieva, Qiong Zhang, Paparao Palacharla, Tadashi Ikeuchi
  • Publication number: 20190097747
    Abstract: Systems and methods for identifying a pair of nodes of a plurality of nodes of a virtual optical network (VON); identifying i) an optical route between the pair of nodes and ii) a desired availability of the optical route; determining a probability density function (PDF) of a signal-to-noise ratio (SNR) of a signal of the optical route; determining a SNR threshold such that an integration of the PDF of the SNR of the signal above the SNR threshold corresponds to the desired availability of the optical route; determining a plurality of spectral efficiencies that corresponds to the SNR threshold, each spectral efficiency of the plurality of spectral efficiencies associated with a respective modulation format of a plurality of modulation formats; and identifying a particular modulation format of the plurality of modulation formats that corresponds to a maximum spectral efficiency of the plurality of spectral efficiencies.
    Type: Application
    Filed: October 8, 2018
    Publication date: March 28, 2019
    Applicant: Fujitsu Limited
    Inventors: Inwoong Kim, Xi Wang, Olga Vassilieva, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10243688
    Abstract: Methods and systems for reach extension of multi-carrier channels using unequal subcarrier spacing may decrease FWM by grouping the subcarriers into groups of 2 subcarriers, and apply a secondary, unequal spacing between the groups. In this manner, nonlinear interactions may be reduced and the transmission reach of a multi-carrier channel may be extended.
    Type: Grant
    Filed: June 12, 2017
    Date of Patent: March 26, 2019
    Assignee: FUJITSU LIMITED
    Inventors: Olga Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Patent number: 10230661
    Abstract: Systems and methods for performing distributed virtual network embedding are disclosed. A resource orchestrator may receive a virtual network request specifying a set of virtual nodes, a set of virtual links, each connecting two virtual nodes in a mesh topology, and resource requirements for some virtual nodes. The orchestrator may partition the virtual network request into multiple sub-requests, each specifying a linear topology for a subset of the virtual nodes and links within the mesh topology. The sub-requests may collectively include all virtual links within the mesh topology with no overlapping links. Resource orchestrators may collaborate to compute, independently for each sub-request, a respective chaining solution in which each virtual node is mapped to a physical node having resources sufficient to implementing the virtual node. A resource orchestrator may combine the respective chaining solutions for each of the sub-requests to generate a mapping solution for the virtual network request.
    Type: Grant
    Filed: February 3, 2017
    Date of Patent: March 12, 2019
    Assignee: FUJITSU LIMITED
    Inventors: Qiong Zhang, Paparao Palacharla, Tadashi Ikeuchi, Xi Wang, Inwoong Kim
  • Patent number: 10225008
    Abstract: A disclosed method for configuring an optical network includes determining that a measure of performance for a first optical path is approaching a safe threshold and designating the first optical path as at risk for performance degradation due to additional traffic. The method also includes, in response to adding a new optical path, calculating a system margin for the first optical path representing a difference between an OSNR delivered on the first optical path and a required OSNR for error-free operation on the first optical path, determining that the system margin is insufficient to meet an applicable performance level, modifying an operating parameter of a transmitter or receiver of the first optical path and refraining from calculating a system margin for a second optical path that is not designated as at risk for performance degradation. The method may be implemented by a network management system of the optical network.
    Type: Grant
    Filed: April 27, 2018
    Date of Patent: March 5, 2019
    Assignee: Fujitsu Limited
    Inventors: Olga I. Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Publication number: 20180359047
    Abstract: Methods and systems for reach extension of multi-carrier channels using unequal subcarrier spacing may decrease FWM by grouping the subcarriers into groups of 2 subcarriers, and apply a secondary, unequal spacing between the groups. In this manner, nonlinear interactions may be reduced and the transmission reach of a multi-carrier channel may be extended.
    Type: Application
    Filed: June 12, 2017
    Publication date: December 13, 2018
    Inventors: Olga Vassilieva, Inwoong Kim, Tadashi Ikeuchi
  • Patent number: 10148552
    Abstract: Methods and systems are provided for determining a shortest path with a constraint in an optical network. The method includes identifying a permitted number of events defined by the constraint. The method further includes creating virtual nodes for each node in the optical network, the virtual nodes corresponding with the permitted number of events. The method also includes traversing the virtual nodes from a source node to a destination node with a shortest path algorithm, wherein traversing the virtual nodes comprises creating virtual links between the virtual nodes when the constraint is not violated, the virtual link corresponding with a physical link; and identifying a shortest path between the source node and the destination node from the virtual links, the shortest path not violating the constraint.
    Type: Grant
    Filed: May 31, 2016
    Date of Patent: December 4, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Inwoong Kim, Xi Wang, Qiong Zhang, Paparao Palacharla, Tadashi Ikeuchi
  • Patent number: 10116392
    Abstract: Carrier suppression (CS-M-PAM) may be applied to M-PAM modulated optical signals to improve transmission reach. Additional rescaling of CS-M-PAM, referred to as adaptive CS-M-PAM, may further improve transmission reach by reducing low level symbol interference.
    Type: Grant
    Filed: January 19, 2018
    Date of Patent: October 30, 2018
    Assignee: FUJITSU LIMITED
    Inventors: Inwoong Kim, Olga Vassilieva, Paparao Palacharla, Tadashi Ikeuchi