Patents Assigned to Korea Telecom Freetel Co., Ltd.
  • Patent number: 6681111
    Abstract: Disclosed is a roaming service system in a CDMA service area for GSM service subscribers, which comprises a CDMA system comprising a CDMA HLR storing information on subscribers' locations and services, a CDMA MSC connected to the CDMA HLR and accessing calls, and a CDMA terminal wirelessly connected to the CDMA MSC and capable of having a SIM card removably installed therein; a GSM system comprising a GSM HLR storing information on the subscribers' locations and services, a GSM MSC connected to the GSM HLR and accessing calls, an authentication center (AuC) connected to a GSM network and authenticating terminals, and a GSM terminal wirelessly connected to the GSM MSC; and an IRGS connected between the CDMA system and the GSM system and converting signals to execute signal communications between the systems, and when a subscriber of a service provided by the GSM system moves to an area in which the subscriber can use the service provided by the CDMA system and installs the subscriber's SIM card
    Type: Grant
    Filed: April 16, 2001
    Date of Patent: January 20, 2004
    Assignee: Korea Telecom Freetel Co., Ltd.
    Inventors: Byung-Ik Ahn, Chan-Ho Yun, Yuon-Pil Jeung, Kwang-Wuk Lee, Cheol-Hyun Kang, Seong-Jin Choi
  • Patent number: 6127973
    Abstract: A signal processing apparatus for minimizing interference and for reducing effects of noise by controlling beam patterns of a telecommunication system having an array antenna, comprising: a means for computing a residue vector, by using a signal vector provided from said array antenna at each snapshot, a final array output signal of said telecommunication system at the last previous snapshot and a value of a gain vector of the present snapshot, and for outputting said residue vector; a means for synthesizing a scalar value, which is needed to generate a search direction vector, from said residue vector; a means for producing said search direction vector, by using said residue vector and said scalar value; a means for producing an adaptive gain, by using said signal vector, said search direction vector, said final array output signal of said telecommunication system at the last previous snapshot and the value of said gain vector of the present snapshot; and a means for updating said gain vector, by using said
    Type: Grant
    Filed: April 18, 1997
    Date of Patent: October 3, 2000
    Assignee: Korea Telecom Freetel Co., Ltd.
    Inventors: Seung Won Choi, Dong Un Yun
  • Patent number: 5999800
    Abstract: This invention provides a design technique of the array antenna, and a telecommunication system and method utilizing the array antenna for enhancing the communication quality and increasing the communication capacity by reducing the interfering signals and noises with the nice beam pattern. And, the design technique of the array antenna, and the telecommunication system and method utilizing the array antenna introduce a simplified computational technique for generating a nice beam pattern having its maximum gain along the direction of the wanted signal and maintaining the gain toward the direction of the interfering signals in as low a level as possible.
    Type: Grant
    Filed: April 18, 1997
    Date of Patent: December 7, 1999
    Assignee: Korea Telecom Freetel Co., Ltd.
    Inventors: Seung Won Choi, Dong Un Yun