Patents Assigned to NTT Mobile Communications
  • Patent number: 6031415
    Abstract: The present invention provides a matched filter circuit available for processing long P/N codes in a small size circuit. A matched filter circuit according to the present invention performs the following processes in the proposed invention: i) sampling and holding circuits multiply part of the number of a long code; ii) multipliers are input in parallel to the sampling and holding circuit from the first multiplier register which can hold as many PN codes as the number of the sampling and holding circuits in i); iii) the PN codes are stored in the second multiplier register of the same capacity of the first multiplier resister when there is a PN code to be used sequentially to be PN codes; and iv) the PN codes in the second multiplier register are transmitted in parallel to the first multiplier register. The PN code is input to the second multiplier register in serial.
    Type: Grant
    Filed: October 18, 1996
    Date of Patent: February 29, 2000
    Assignees: NTT Mobile Communications Network, Inc., Yozan Inc.
    Inventors: Guoliang Shou, Changming Zhou, Makoto Yamamoto, Mamoru Sawahashi, Fumiyuki Adachi, Sunao Takatori
  • Patent number: 6026115
    Abstract: A RAKE receiver which is employed in a direct sequence spread spectrum communication system, and which can effectively receive multipath signals. A path searcher measures the amplitude of each path, selects N paths with larger amplitudes in descending order of magnitude, where N is the number of despreaders, and assigns the despreaders to the selected paths to despread the signals of the paths. This assignment of the despreaders to the paths is carried out such that a path with a large amplitude and a path with a small amplitude are assigned to adjacent despreaders and are input to the same pre-detection combiner. The outputs of the despreaders are combined by the pre-detection combiners, and detected by detectors whose outputs are RAKE combined by a post-detection combiner.
    Type: Grant
    Filed: August 18, 1997
    Date of Patent: February 15, 2000
    Assignee: NTT Mobile Communications Network, Inc.
    Inventors: Akihiro Higashi, Koji Ohno, Seizou Onoe
  • Patent number: 6026279
    Abstract: A method and an apparatus for signal transmission in a CDMA mobile communication system which are capable of preventing an unnecessary increase of an amount of interference power due to the signal transmission through a radio channel and thereby preventing an unnecessary decrease of a system capacity. The radio channel transmission signals are transmitted through the radio channel, where the radio channel transmission signals contain the transmission signals which are formed by control signals or user signals and necessary signals which are necessary in maintaining the radio channel, and this radio channel transmission is controlled so that only signal portions for the necessary signals are transmitted without transmitting any other signal portions when there is no transmission signal to be transmitted.
    Type: Grant
    Filed: June 12, 1997
    Date of Patent: February 15, 2000
    Assignee: NTT Mobile Communications Networks, Inc.
    Inventors: Takehiro Nakamura, Seizo Onoe, Kouji Ohno
  • Patent number: 6021516
    Abstract: In a communication system having a transmission station which transmits the data signal and a receiving station which receives the data signal, the transmission station consists of an adding means for adding an error detecting code showing a position of a transmission error, which occurs on said data signal, in said data signal to said data signal and a retransmission means for retransmission of a part in said data signal when said receiving station requests the retransmission of the part in said data signal. The receiving station consists of a judgment means for judging a position of the transmission error in said data signal on the basis of the error detecting code which is added by the adding means and a request means for requesting the retransmission of the part containing the transmission error in the data signal on the basis of the position of the transmission error.
    Type: Grant
    Filed: January 21, 1997
    Date of Patent: February 1, 2000
    Assignee: NTT Mobile Communications Network, Inc.
    Inventors: Ichiro Okajima, Akihiro Maebara, Katsumi Kobayashi, Koji Sasada, Hiroyuki Hattori
  • Patent number: 6011787
    Abstract: A CDMA mobile communication scheme capable of increasing a number of sectors while not increasing a number of perch channel spread codes and not jamming the control channel traffic, so as to obtain the capacity increase effect by the use of the sector configuration effectively. At the base station, a perch channel spread by an identical perch channel spread code assigned to the base station is transmitted from each one of at least two sectors of the base station. Then, upward signals from each mobile station are received at more than one reception sectors, the upward signals received at more than one reception sectors are despread by using an identical uplink spread code, and a maximal ratio combining of despread upward signals is carried out, in a case of carrying out a simultaneous reception at more than one reception sectors.
    Type: Grant
    Filed: March 20, 1997
    Date of Patent: January 4, 2000
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Etsuhiro Nakano, Takehiro Nakamura, Seizo Onoe
  • Patent number: 6009088
    Abstract: In order for the user to perform a transmission of packet data to a desired communication counterpart on a virtual network across a wireless circuit exchange type network system and a LAN without being bothered by address exchange between an address of a physical network and an address of a virtual network, an exchange (10a) performs an address exchange necessary for establishing a communication channel between the terminal equipments within the system using a conversion table, in a mobile wireless data communication system in which a wireless circuit type network system comprising a wireless mobile station (30a), a wireless connection equipment (20a) and the exchange (10a) is connected to a LAN (40a) through a TA (60a) and a router (50a).
    Type: Grant
    Filed: July 29, 1997
    Date of Patent: December 28, 1999
    Assignee: NTT Mobile Communications Network, Inc.
    Inventors: Tsutomu Taguchi, Shinji Kobayashi, Yoshiki Fujima, Kazushige Tanaka, Masahiko Hirono
  • Patent number: 5995837
    Abstract: A handover control is executed when a location area of the mobile station is changed. The communication channel applied is the optimum route suited for the roaming destination of the mobile station. A service controller 6 is provided in the mobile communication network, switching node information transmitters 7 are provided in switching nodes 151, 131 and 132 so as to transmit, to the service controller 6, switching node informations representing the nodes themselves. Furthermore, in the service controller 6, a memory 8 for storing the switching node informations, and a handover execution unit 9 for executing handover control are provided.
    Type: Grant
    Filed: August 2, 1996
    Date of Patent: November 30, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Yukichi Saito, Yasuo Maruyama, Masami Yabusaki
  • Patent number: 5991642
    Abstract: Communication is carried out on the basis of an optimum speech coding scheme that is matched to the speech coding schemes provided by the radio zones, and to the speech coding capabilities of the mobile stations. To achieve this, when a traffic channel is set up between a mobile station and a switch, a traffic channel selection condition that has been specified by the switch on the basis of the speech coding capabilities of the mobile station that made the SETUP request and of the mobile station to which the call is made, is stored in the control station. The control station grasps which speech coding scheme is currently being used in the radio zone which it controls. Moreover, by transferring the selection conditions specified by the switch and using these conditions as information required for channel setup by another control station, communication can be carried out using a high-priority speech coding scheme when handover occurs.
    Type: Grant
    Filed: September 10, 1996
    Date of Patent: November 23, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Yasuyuki Watanabe, Noriya Nakaima, Kouji Yamamoto, Moritoshi Katuta
  • Patent number: 5983097
    Abstract: A mobile communication scheme capable of notifying a communication regulation information efficiently by using radio interfaces from the macro-cell system to the micro-cell system, without requiring communications through a fixed communication network, so as to be able to regulate the service through the micro-cell system efficiently in coordination with the regulation of the service through the macro-cell system. In this mobile communication scheme, the communication regulation information is notified from the macro-cell system to the mobile station while the mobile station is located within the macro-cell system, and stored in a memory of the mobile station.
    Type: Grant
    Filed: October 2, 1997
    Date of Patent: November 9, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Kazuhiko Kakinuma, Masaaki Yoshimi, Tatsuaki Wakabayashi, Kiyohito Nagata
  • Patent number: 5963847
    Abstract: A booster system for transmitting a received wave after amplifying it comprises a receiving antenna section, a carrier combining section, a transmitting section, a transmitting antenna section and a parameter control section. The carrier combining section multiplies a canceling signal by a cancel parameter to obtain a replica signal, then combines it with a received signal in at least one of the radio frequency band, the intermediate frequency band and the base band, and derives a combined base band signal from the combined signal. The transmitting section generates a send signal and a canceling signal by using a signal demodulated through the demodulation of the combined base band signal. Based on the combined base band signal and the canceling signal, the parameter control section determines a canceling parameter such that the power of the combined base band signal is reduced, the parameter being provided to the carrier combining section.
    Type: Grant
    Filed: June 25, 1997
    Date of Patent: October 5, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Kazuhito Ito, Hiroshi Suzuki, Manabu Nakada, Yoshio Ebine
  • Patent number: 5963550
    Abstract: In order to provide a packet transfer scheme in which various data can easily be used commonly with other communication methods and a packet can be transferred at a high speed, a mobile communication system comprises a database (20) for storing an identification number of a mobile terminal (40) and location information indicating a zone in which the mobile terminal is currently located, a packet switch (10), and another packet switch (30) capable of communication when the mobile terminal (40) is located in a zone under the packet switch (30). The packet switch (10) inquires of the database (20) about the location information of the mobile terminal (40) when the packet switch (10) receives a packet addressed to the mobile terminal (40). When the mobile terminal (40) is located in the zone under the packet switch (30), the packet is transferred to the mobile terminal (40) through the packet switch (30).
    Type: Grant
    Filed: August 29, 1996
    Date of Patent: October 5, 1999
    Assignee: NTT Mobile Communications Network, Inc.
    Inventors: Shoichi Hirata, Masumi Sotoyama, Kimio Ikeda, Kazuo Sugiyama, Atsushi Shimokawa, Koji Yamamoto, Akihisa Nakajima
  • Patent number: 5959983
    Abstract: A radio communication system which keeps to a minimum the number of slots which cannot be used due to interference from a neighboring base station, and which can increase the slot usage efficiency. A slot/frame setting unit for a base station extracts the slot/frame timing of a neighboring base station based on the reception output of a radio unit, and sets the communication frame by displacing it in such a way that two slots in the own base station do not coincide in time with a slot of the neighboring base station based on this timing. This setting ensures that there is always just a single slot which cannot be used when interference is detected.
    Type: Grant
    Filed: June 14, 1996
    Date of Patent: September 28, 1999
    Assignees: Kabushiki Kaisha Toshiba, NTT Mobile Communications Network, Inc.
    Inventors: Naritoshi Saito, Manabu Ishibe, Shouichi Oshima, Yoshinori Nagao
  • Patent number: 5960336
    Abstract: A data receiving apparatus is constructed to make comparison of received signal strength of a plurality of receiving antennas by making use of timing of a sync word, which is not necessary for making synchronization acquisition, among a plurality of sync words contained in a subframe of a receiving signal, and then to select a receiving antenna of the highest received signal strength from among the plurality of receiving antennas, in accordance with a result of the comparison made before then.
    Type: Grant
    Filed: May 6, 1997
    Date of Patent: September 28, 1999
    Assignees: Matsushita Communication Industrial Co., Ltd., NTT Mobile Communications Network Inc.
    Inventors: Keiichi Ikawa, Tetsuaki Nakanishi, Kazuhisa Tsubaki, Kazuhiro Umetsu, Tadao Takami
  • Patent number: 5953378
    Abstract: Likelihood calculating circuit A1 calculates the hamming distance between a received data series and a unique word as likelihood data d1. Likelihood calculating circuit A2 calculates the number of transmission errors using redundant data, and outputs this value as likelihood data d2. Likelihood data d1,d2 are added at adding circuit 21, and the output thereof is compared to the threshold value of determination circuit with threshold 22. The results of this comparison are output as determination signal with threshold DT. Synchronous determination circuit 23 generates a synchronous determination signal SD based on determination signal with threshold DT. Accordingly, the present invention provides a frame synchronization circuit in which it is possible to avoid out of synchronization or false synchronization, without increasing the amount of redundancy necessary to detect frame synchronization.
    Type: Grant
    Filed: September 19, 1997
    Date of Patent: September 14, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Sanae Hotani, Toshirou Kawahara, Toshio Miki
  • Patent number: 5953326
    Abstract: A cell selection scheme in a CDMA mobile communication system which is capable of shortening the cell selection processing time while constructing a mobile communication system with a practically feasible base station configuration. In a CDMA mobile communication system, first type base stations which share a common reference timing are transmitting pilot channels spread by using an identical pilot channel spread code at mutually different spread code phases with respect to the common reference timing where these mutually different spread code phases are assigned to different first type base stations, and second type base stations which do not share the common reference timing are transmitting pilot channels spread by using mutually different pilot channel spread codes at arbitrary spread code phases where these mutually different pilot channel spread codes being assigned to different second type base stations.
    Type: Grant
    Filed: March 6, 1997
    Date of Patent: September 14, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Takehiro Nakamura, Kouji Ohno, Etsuhiro Nakano, Seizo Onoe
  • Patent number: 5953324
    Abstract: A CDMA mobile communication system, which produces a time for monitoring peripheral base stations using different radio frequencies for carrying out hand-off between base stations using different radio frequencies without momentary cutoff of communication. A mobile station (504) of the CDMA mobile communication system discontinues error correction decoding on reception signal, outputs a user data which is not error correction decoded and, during the non-reception time in the blank time, changes over a reception frequency to a radio frequency of a neighboring base station monitor a reception level of the neighboring base station. During a hand-off period between a base station under communication (502) and a new base station (503) which differ in used frequency, the base station under communication and the new base station transmit only a user data portion, but do not transmit transmission signal in a transmission period for transmitting an error correction coding check bits.
    Type: Grant
    Filed: January 31, 1997
    Date of Patent: September 14, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventor: Fumiyuki Adachi
  • Patent number: 5940433
    Abstract: In a mobile communication system using spread spectrum, performing respective multiplications of an I and Q channel signals by a spreading code replica, integration over one spreading code period, and square-law detection of the integrated signals to remove data modulation components and residual carrier frequency components. The square-law detected signals are added to obtain signal power over one spreading code period while updating the clock phase of a digital control clock generator. The information of power is stored in a memory in an acquisition mode controller, and the clock phase of the digital control clock generator 30 is fixed at the spreading code replica phase at which a maximum correlation detection power over one spreading code period is obtained. Subsequently, a confirmation mode is started for confirming the spreading code acquisition phase.
    Type: Grant
    Filed: February 12, 1997
    Date of Patent: August 17, 1999
    Assignee: NTT Mobile Communications Network, Inc.
    Inventors: Mamoru Sawahashi, Akihiro Higashi, Kenichi Higuchi
  • Patent number: 5940385
    Abstract: A multicellular transmission apparatus in a mobile communication network, capable of preventing delay involved in reassembling short packets into fixed length packets (ATM cells), degradation of communication signals due to the delay, and reduction of the transmission efficiency involved in assembling the short packets into the fixed length packets. When low speed information transmitted from a telephone set is converted into short packets by communication data assemblers/disassemblers in a mobile gateway switching center, followed by multiplexing of the short packets into the fixed length packets by fixed length packet assemblers/disassemblers, the short packets sent from a plurality of telephone sets are grouped for each destination node (a particular radio base station, for example) in the network, and are multiplexed into the fixed length packets belonging to the group bound for the destination of the short packets.
    Type: Grant
    Filed: October 22, 1996
    Date of Patent: August 17, 1999
    Assignee: NTT Mobile Communications Network, Inc.
    Inventors: Yasuhiro Mita, Masami Yabusaki, Narumi Umeda
  • Patent number: 5933782
    Abstract: A downlink transmission power control scheme for a mobile communication system using the site diversity, which carries out a primary downlink transmission power control using a primary control signal which is transmitted from the mobile station and terminated at each base station, and an additional downlink transmission power control using additional control signals which are transmitted from the base station control station to the base stations. The additional downlink transmission power control may also use a secondary control signal which is transmitted from the mobile station and terminated at the base station control station. The primary downlink transmission power control can be carried out during a non-site diversity period while the additional downlink transmission power control is carried out during the site diversity period, or the primary downlink transmission power control and the additional downlink transmission power control can be both carried out during the site diversity period.
    Type: Grant
    Filed: July 29, 1997
    Date of Patent: August 3, 1999
    Assignee: NTT Mobile Communications Network Inc.
    Inventors: Etsuhiro Nakano, Takehiro Nakamura, Koji Ohno, Takaaki Sato
  • Patent number: 5926512
    Abstract: A matched filter circuit for mobile communications is disclosed. The circuit may be fabricated in a small size using large-scale integration and can perform high-speed processing and double sampling at a reduced rate of power consumption. In one embodiment, a plurality of sampling and holding circuits each including a switch are divided into two groups. A control circuit successively closes one of the switches in the first group every chip time, while successively closing one of the switches in the second group at a timing shifted by one-half chip time from that of the first group, thereby enabling a double-sampling operation. Outputs of the sampling and holding circuits in each group are summed by an analog circuit with a high degree of linearity, resulting in a high processing speed combined with a reduced circuit size and power consumption.
    Type: Grant
    Filed: October 23, 1996
    Date of Patent: July 20, 1999
    Assignees: Yozan Inc., NTT Mobile Communications Network, Inc.
    Inventors: Guoliang Shou, Changming Zhou, Makoto Yamamoto, Sunao Takatori, Mamoru Sawahashi, Fumiyuki Adachi