Patents by Inventor Efstratios Skafidas

Efstratios Skafidas 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).

  • Patent number: 6983030
    Abstract: An approach for processing data received from a communications channel in finite precision arithmetic applications generally involves equalizing received data in the time domain prior to demodulation using finite impulse response (FIR) filtering. FIR coefficients used in FIR filtering are selected to minimize SNR degradation attributable to ISI and roundoff errors due to finite precision arithmetic, thereby maximizing channel capacity. The approach considers the communications channel noise attributable to crosstalk, white noise and analog to digital converter quantization noise, ISI attributable to failure of the equalizer coefficients to completely eliminate ISI, round off noise due to the use of finite precision arithmetic in the equalizer and roundoff noise due to the use of finite precision arithmetic in the FFT algorithm.
    Type: Grant
    Filed: January 2, 2001
    Date of Patent: January 3, 2006
    Assignee: Bandspeed, Inc.
    Inventors: Andrew Storm, Shane Michael Tonissen, Efstratios Skafidas
  • Publication number: 20040259563
    Abstract: The present invention provides in one embodiment channel allocation and polarization techniques for reducing cross sector communications interference in a multiple access wireless communications environment. In one embodiment, channel allocation and/or polarization techniques may be applied in multiple-access wireless communications architectures to provide selective, simultaneous communications with wireless devices using a plurality of transmitters. In some embodiments, a transmitter is coupled to an antenna configured to provide simultaneous communications with wireless devices located in different spatial areas or sectors. In some embodiments, communications between wireless devices within a single sector, between wireless devices in different sectors and between wireless devices and a wired network or wireless backhaul network may be provided.
    Type: Application
    Filed: June 1, 2004
    Publication date: December 23, 2004
    Inventors: John Jack Morton, Ben Jones, Efstratios Skafidas
  • Publication number: 20040259558
    Abstract: A multiple access wireless communications architecture provides selective, simultaneous communications with wireless devices located in different sections of a spatial area around a communications apparatus referred to as “sectors”. In one embodiment, channel allocation techniques for increasing one or more of throughput and coverage in a wireless communications environment.
    Type: Application
    Filed: June 16, 2004
    Publication date: December 23, 2004
    Inventors: Efstratios Skafidas, Ben Jones, John "Jack" Morton, Mike Gibson, Neil Patrick Kelly, Nestor Fesas, Mark William Benson, Richard John Rusnak, James Glick, Duy Khuong Do, Douglas A. Mammoser, Lei Cheng, Kevin Sean Broe, Natarajan Ekambaram
  • Patent number: 6804313
    Abstract: An approach for processing data received from a communications channel generally involves equalizing received data in the time domain prior to demodulation by an approach that incorporates mitigation of interference. Oversampling of the received signal provides improved equalization performance and mitigation of interference, such as crosstalk. A receiver oversamples a received signal and splits the signal into a set of observation sequences. The set of observation sequences are processed to provide an estimate of the input to the communications channel, while providing at least partial rejection of any interfering signal. Exact knowledge of the parameters of the interference signal is not required.
    Type: Grant
    Filed: January 2, 2001
    Date of Patent: October 12, 2004
    Assignee: Bandspeed, Inc.
    Inventors: Efstratios Skafidas, Shane Michael Tonissen
  • Publication number: 20040102222
    Abstract: A multiple access wireless communications architecture provides selective, simultaneous communications with wireless devices located in different sections of a spatial area around a communications apparatus referred to as “sectors”. This includes communications between wireless devices in a single sector, between wireless devices in different sectors and between wireless devices and a wired network or wireless backhaul network. The wireless communications architecture generally includes two or more wireless antenna arrangements that are each configured to provide communications with wireless devices located in a particular sector. Each wireless antenna arrangement is further configured to determine whether signals are being communicated on a communications channel before transmitting on the communications channel. This may be implemented, for example, using a carrier sense or energy detection mechanism.
    Type: Application
    Filed: July 7, 2003
    Publication date: May 27, 2004
    Inventors: Efstratios Skafidas, Ben Jones, Antonio Torrini, John Jack Morton, Eric Crawford, Mike Gibson, William John Rinderknecht, Mark William Benson, Neil Patrick Kelly, Nestor Fesas, Michael Casey Luther, Blaine Kohl
  • Publication number: 20020136268
    Abstract: An approach for selecting sets of communications channels involves determining the performance of communications channels. A set of channels is selected based on the results of performance testing and specified criteria. The participant generates data that identifies the selected set of channels and provides that data to other participants of the communications network. The participants communicate over the set of channels, such as by using a frequency hopping protocol. When a specified time expires or monitoring of the performance of the channel set identifies poor performance of the set of channels, the participant selects another set of channels for use in communications based on additional performance testing. By selecting channels based on the initial performance testing and performance monitoring, the communications network adaptively avoids channels with poor performance.
    Type: Application
    Filed: September 6, 2001
    Publication date: September 26, 2002
    Inventors: Hongbing Gan, Bijan Treister, Efstratios Skafidas
  • Publication number: 20020131537
    Abstract: An approach for processing data received from a communications channel that minimizes noise power and optimizes impulse response length to reduce interference, such as from inter-symbol interference (ISI) and inter-channel interference (ICI), is disclosed. For example, finite impulse response (FIR) filtering may be used with FIR coefficients that are determined by optimizing a function of the impulse response length and the noise power. The impulse response length is optimized based on the communications channel transfer function to reduce interference. The noise power is minimized based on the noise covariance as determined using the total noise power density. The approach accounts for noise from a variety of interference sources besides ISI and ICI. The result is a superior equalizer for use in communications receivers employing orthogonal frequency division multiplexing or discrete multitone modulation in communications protocols employing Asymmetric Digital Subscriber Line, G.
    Type: Application
    Filed: January 22, 2002
    Publication date: September 19, 2002
    Inventors: Andrew Storm, Shane M. Tonissen, Efstratios Skafidas
  • Publication number: 20020116460
    Abstract: A novel approach for selecting communications channels and participants with which to communicate based on channel performance and transferring management functions between participants in a communications arrangement is disclosed. According to one aspect of the invention, a particular channel is selected based on channel performance and channel identification data is provided to a participant that sends a response on a channel selected based on the channel identification data. According to another aspect of the invention, a particular participant is selected from a group of participants based on the performance of a particular channel. According to yet another aspect, an associate master participant is selected to assume responsibilities for functions assigned to the master participant if any of a set of handoff criteria are satisfied. For example, the associate master participant may assume the role of the master participant if the master participant can no longer perform the functions.
    Type: Application
    Filed: January 16, 2002
    Publication date: August 22, 2002
    Inventors: Bijan Treister, Hongbing Gan, Efstratios Skafidas
  • Publication number: 20020098841
    Abstract: A novel approach for transferring management functions between participants generally involves the use of an associate master participant that assumes responsibilities for functions assigned to the master participant if the master participant can no longer perform the functions. A participant in a communications arrangement is designated as the master participant and is responsible for performing one or more functions. Another participant from the communications arrangement is designated as an associate master participant. The associate master participant assumes the role of master participant, i.e., performs the functions previously assigned to master participant, if any of a set of handoff criteria are satisfied. The particular handoff criteria used may vary depending upon the requirements of a particular application and the invention is not limited to any particular handoff criteria.
    Type: Application
    Filed: August 24, 2001
    Publication date: July 25, 2002
    Inventors: Bijan Treister, Hongbing Gan, Efstratios Skafidas
  • Publication number: 20020097681
    Abstract: An approach for managing communications channels based on performance involves selecting a particular channel based on channel performance. Based on the selected channel, channel identification data is provided to another participant of the communications system to determine on which channel to respond. For example, the other participant may respond on the selected channel, avoid using the selected channel to respond, or skip the selected channel in a sequence of channels, such as a frequency hopping sequence. The communication sent in response may include a performance measurement of the channel used to provide the channel identification data. According to another aspect of the invention, a particular participant is selected from a group of participants based on the performance of a particular channel. According to yet another aspect, performance data is maintained, such as in a lookup table, and the performance data may be shared between participants of the communications system.
    Type: Application
    Filed: September 6, 2001
    Publication date: July 25, 2002
    Inventors: Bijan Treister, Hongbing Gan, Efstratios Skafidas
  • Publication number: 20010036228
    Abstract: An approach for processing data received from a communications channel generally involves equalizing received data in the time domain prior to demodulation by an approach that incorporates mitigation of interference. Oversampling of the received signal provides improved equalization performance and mitigation of interference, such as crosstalk. A receiver oversamples a received signal and splits the signal into a set of observation sequences. The set of observation sequences are processed to provide an estimate of the input to the communications channel, while providing at least partial rejection of any interfering signal. Exact knowledge of the parameters of the interference signal is not required.
    Type: Application
    Filed: January 2, 2001
    Publication date: November 1, 2001
    Inventors: Efstratios Skafidas, Shane Michael Tonissen
  • Publication number: 20010036237
    Abstract: An approach for processing data received from a communications channel in finite precision arithmetic applications generally involves equalizing received data in the time domain prior to demodulation using finite impulse response (FIR) filtering. FIR coefficients used in FIR filtering are selected to minimize SNR degradation attributable to ISI and roundoff errors due to finite precision arithmetic, thereby maximizing channel capacity. The approach considers the communications channel noise attributable to crosstalk, white noise and analog to digital converter quantization noise, ISI attributable to failure of the equalizer coefficients to completely eliminate ISI, round off noise due to the use of finite precision arithmetic in the equalizer and roundoff noise due to the use of finite precision arithmetic in the FFT algorithm.
    Type: Application
    Filed: January 2, 2001
    Publication date: November 1, 2001
    Inventors: A. Storm, Shane Michael Tonissen, Efstratios Skafidas
  • Patent number: 6295326
    Abstract: A computer-implemented approach for reducing distortion in digital communications systems generally involves obtaining an optimal estimation of the original data using a Kalman filter with an increased length state to remove substantially all ISI in the time domain. The use of an increased length state in the Kalman filter provides a more accurate estimate of the transmitted data with relatively little additional computational cost. Subsequent equalization may also be performed in the frequency domain to correct any residual amplitude and phase distortion.
    Type: Grant
    Filed: March 1, 2000
    Date of Patent: September 25, 2001
    Assignee: Bandspeed, Inc.
    Inventors: Shane Michael Tonissen, Efstratios Skafidas, Andrew Logothetis