Patents by Inventor Carl-Erik Sundberg

Carl-Erik Sundberg 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: 4807253
    Abstract: There are described apparatus and methods for producing time-varying of trellis-coded modulations, specifically, time-varying trellis-coded phase-shift-keying, to facilitate carrier phase recovery when the signal has been exposed to extraneous phase variations and noise.Typically, eight-phase-shift-keying (8-PSK), with rate 2/3 convolutional coding, is followed on a repetitive basis by one or two formats of four-phase-shift-keying (4-PSK), which formats are chosen to ease phase synchronization and to conserve the use of bandwidth and not to worsen the bit error probability while reducing the probability of synchronization loss and the length of error bursts or "random walks".The variation of the modulation formats could be:(1) 8-PSK (rate 2/3) followed by 4-PSK,(2) 8-PSK (rate 2/3) followed by 4-PSK (preferred format) and then 4-PSK (secondary format) or,(3) any of many other periodic formats of 8-PSK and 4-PSK sections.
    Type: Grant
    Filed: November 13, 1987
    Date of Patent: February 21, 1989
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Joachim Hagenauer, Carl-Erik Sundberg
  • Patent number: 4797879
    Abstract: The present invention relates to packet switched interconnection protocols for use in high-speed optical Star-configured Local Area Networks (LANs). In the present Star LAN, a plurality of N+1 wavelength division multiplexed (WDM) channels are provided for use by M transceivers connected to the Star coupler, where preferably M>N. N of the N+1 WDM channels are used for transmission of data packets, and the remaining WDM channel is used by all transceivers for transmitting control packets only. In the present protocols, a transmitter in an active transceiver first send a control packet over the control channel using a first protocol such as, for example, ALOHA or CSMA. The control packet includes (1) the transmitter's unique address, (2) the destined receiver's address, and (3) the address of the data channel to be used in transmitting the associated data packet.
    Type: Grant
    Filed: June 5, 1987
    Date of Patent: January 10, 1989
    Assignee: American Telephone and Telegraph Company AT&T Bell Laboratories
    Inventors: Isam M. I. Habbab, Mohsen Kavehrad, Carl-Erik Sundberg
  • Patent number: 4701909
    Abstract: The present invention relates to a collision detection technique for an optical Star LAN using CSMA/CD. The present technique is implemented by preferably adding two or more fixed Hamming weight sequences, e.g., a fixed even or odd number of 1's in each unique cyclic error correcting code word, to the preamble section of each packet of information to be transmitted. These collision detection sequences have a length which is beyond the vulnerable time period of the CSMA/CD protocol (maximum round-trip propagation delay for each packet) by at least one code word length in order to prevent any misdetection, or false detection, of a collision. Each receiver in the listening period, looks for a code pattern with a fixed Hamming weight. When code patterns collide, the Hamming weight of the resulting code word in the collision period will exceed the nominal sequence weight (will include more 1's than the fixed Hamming weight) and a sequence weight violation is detected.
    Type: Grant
    Filed: July 24, 1986
    Date of Patent: October 20, 1987
    Assignee: American Telephone and Telegraph Company, AT&T Bell Laboratories
    Inventors: Mohsen Kavehrad, Carl-Erik Sundberg
  • Patent number: 4236247
    Abstract: An apparatus for a semiconductor memory in a data processing system, which performs real-time single and double error detection and correction, as well as triple error detection. The syndrome of the data word read from the memory is stored when a first error is detected. Said stored syndrome is used later for error correction when a second error is detected and in parallel it is combined logically with the actual syndrome word for deriving the syndrome corresponding to the second error, said second syndrome serving for error correction. The second syndrome can also be stored for permitting real-time triple error detection.
    Type: Grant
    Filed: January 15, 1979
    Date of Patent: November 25, 1980
    Assignee: Organisation Europeene de Recherches Spatiales
    Inventor: Carl-Erik Sundberg