Patents Assigned to NEC Communication Systems, Ltd.
  • Publication number: 20130336188
    Abstract: A wireless base station (1) includes a wakeup device (13) and a main device (14). When the main device (14) is in a sleep mode, the wakeup device (13) is connected to the antenna (11). Then, when the wakeup device (13) receives a wakeup signal for activating the wireless base station (1) from a terminal device assigned to the wireless base station (1) in a communication band used for wireless communication with the terminal device and when the information for identifying a wireless base station to be activated contained in the received wakeup signal is identical with the identification information of the wireless base station (1), the wakeup device (13) outputs a driving signal to the main device (14). The main device (14) transitions from the sleep mode to an operating mode in response to the driving signal from the wakeup device (13).
    Type: Application
    Filed: February 16, 2012
    Publication date: December 19, 2013
    Applicant: NEC COMMUNICATIONS SYSTEMS, LTD.
    Inventors: Hiroyuki Yomo, Yoshihisa Kondo, Suhua Tang, Sadao Obana, Tetsuya Ito, Akira Matsumoto, Koichi Yoshimura
  • Publication number: 20130329621
    Abstract: A terminal device 2 transmits a wireless frame having a frame length or amplitude that represents the ID of a wireless base station 1 to be woken up to the wireless base station 1. The wireless base station 1 detects the wakeup ID from the frame length or amplitude of the wireless frame from the terminal device 2, and, if the detected wakeup ID is identical with its own ID, transitions from a sleep mode to an operating mode. In this case, the wireless frame is the same wireless frame as that transmitted and received by the wireless communication module of the terminal device 2 to and from the wireless base station 1.
    Type: Application
    Filed: February 16, 2012
    Publication date: December 12, 2013
    Applicants: NEC COMMUNICATIONS SYSTEMS, LTD., ADVANCED TELECOMMUNICATIONS RESEARCH INSTITUTE INTERNATIONAL
    Inventors: Yoshihisa Kondo, Hiroyuki Yomo, Suhua Tang, Sadao Obana, Tetsuya Ito, Koichi Yoshimura, Masahito Iwai, Toshiyasu Tanaka, Hiroyuki Iizuka
  • Publication number: 20130091137
    Abstract: An information classification system 100 includes: a classified information storing part 101 for storing classified information having already been classified into a certain group and group specification information for specifying the group, in association with each other; and a confidence calculating part 102 for calculating confidence having a value depending on a probability that a group which is specified based on unclassified information as a target to be classified and classified information selected as reference information from among the stored classified information and into which the unclassified information should be classified is a true group.
    Type: Application
    Filed: June 15, 2011
    Publication date: April 11, 2013
    Applicant: NEC COMMUNICATION SYSTEMS, LTD.
    Inventors: Stefan Aust, Akira Matsumoto, Tetsuya Ito, Koichi Yoshimura, Soshi Kuroshima
  • Patent number: 8385260
    Abstract: The present invention is to allow prompt and reliable synchronization of belonging information management table even in environments where there is a possibility of receiving update notification information from a plurality of wireless base stations, without needing unnecessarily large traffic for synchronization of belonging information management table. Wireless base station stores belonging information management table, to which belonging information of a terminal belonging to the base station is associated with, to new/old judgment information for judgment of new/old of update. Belonging information update unit performs update of belonging information including the new/old judgment information thereof. Further, upon receiving update notification information from other wireless base station, the belonging information update unit updates the belonging information management table based on the update notification information.
    Type: Grant
    Filed: December 8, 2008
    Date of Patent: February 26, 2013
    Assignee: NEC Communications Systems, Ltd.
    Inventors: Yoshiaki Takakura, Kenichi Abe, Tetsuya Ito, Akira Matsumoto, Hiroyuki Iizuka, Yuichiro Ezure
  • Publication number: 20120320759
    Abstract: A wireless communication device includes a data transmission and reception section that wirelessly transmits a plurality of test packets; a signal sensing section that senses a power of a spatial radio wave signal on a frequency channel that is the same as the plurality of test packets and outputs sample data of the sensed spatial radio wave signal; a calculation processing section that converts the sample data into time series sample data; a collision detection section that calculates a packet collision rate based on the number of packet collisions and the number of the plurality of test packets if there is a packet collision due to interference of the plurality of test packets with another communication; and a control section that adjusts a parameter that the data transmission and reception section uses based on a calculation result of the collision detection section.
    Type: Application
    Filed: June 12, 2012
    Publication date: December 20, 2012
    Applicant: NEC COMMUNICATION SYSTEMS, LTD.
    Inventors: Peng Shao, Stefan Aust, Akira Matsumoto, Tetsuya Ito, Peter Davis
  • Patent number: 8331781
    Abstract: The present invention is to provide an optical access network in which a remote unit receives an optical burst signal. A central unit (OLT) transmits a DC-balanced optical continuous signal including packets having identification information for identifying each remote unit (ONU) to an optical switching module (OSM). The optical switching module (OSM) receives the DC-balanced optical continuous signal from the central unit (OLT), optically switches the packets based on the identification information, and transmits a DC-balanced optical burst signal including the packets to the remote unit (ONU). The remote unit (ONU) receives the DC-balanced optical burst signal and acquires the packets transmitted to the remote unit (ONU).
    Type: Grant
    Filed: December 27, 2007
    Date of Patent: December 11, 2012
    Assignee: NEC Communication Systems, Ltd.
    Inventors: Takumi Nomura, Hiromi Ueda, Takashi Kuriyama, Toshinori Tsuboi, Hiroyuki Kasai, Hirokazu Kobayashi
  • Publication number: 20120157128
    Abstract: A wireless communication terminal includes a communication status measurement element for measuring communication status data representing a communication status of the self terminal at the time of wireless communications; a reference data storage element for storing respective pieces of preset reference data representing communication statuses of a terminal which can be measured at respective locations at the time of wireless communications, in association with respective pieces of location data identifying the respective locations, and a location specifying element for comparing the communication status data measured by the communication status measurement element with the respective pieces of reference data stored in the reference data storage element, and based on the comparison result, specifying a location corresponding to the location data associated with a particular piece of reference data as a location of the self terminal.
    Type: Application
    Filed: August 28, 2010
    Publication date: June 21, 2012
    Applicant: NEC COMMUNICATION SYSTEMS, LTD
    Inventors: Stefan Aust, Tetsuya Ito, Akira Matsumoto, Peter Christopher Davis
  • Patent number: 8184584
    Abstract: In wireless communication using links with neighbor wireless devices, a wireless device calculates ratios of throughput to maximum throughput for the links and calculates the costs of the links using the calculated ratios. Then the wireless device finds, for each destination, a route in which the sum of such calculated link costs is the minimum, and sends a packet to the destination using the route. As a consequence, routing can be done according to an isotonic, easy-to-implement routing protocol.
    Type: Grant
    Filed: October 23, 2008
    Date of Patent: May 22, 2012
    Assignees: NEC Communications Systems, Ltd., Advanced Telecommunications Research Institute International
    Inventors: Yoshihisa Kondo, Satoko Itaya, Peter Davis, Ryutaro Suzuki, Sadao Obana, Tetsuya Ito, Akira Matsumoto
  • Patent number: 8116688
    Abstract: A wireless apparatus which can realize a DFS function that avoidance of interference with radar is considered in an Ad-Hoc mode under a multihop circumstance is provided. A Beacon frame is transmitted at a shorter interval than a previously set interval when radar is detected by wireless apparatuses N1 to N6 which have a DFS function which perform avoidance of interference with radar.
    Type: Grant
    Filed: December 10, 2008
    Date of Patent: February 14, 2012
    Assignee: NEC Communications Systems, Ltd.
    Inventors: Akira Matsumoto, Tetsuya Ito, Kenichi Abe, Hiroaki Ueno, Yoko Suzuki, Dai Someya, Naoki Yokoyama, Akira Shimomura
  • Patent number: 8095138
    Abstract: A wireless communication system allocates resource information used in performing wireless communication to wireless base stations in order not to generate interference between access-side wireless interfaces and backbone-side wireless interfaces. Each of the wireless base stations includes an access-side wireless interface for covering wireless terminal devices and a backbone-side wireless interface for connecting the wireless base stations with each other. The wireless base station allocates resource information that is common to the wireless base stations to the backbone-side wireless interface that performs the wireless communication between the wireless base stations, and allocates resource information that does not generate interference with the backbone-side wireless interface to the access-side wireless interface.
    Type: Grant
    Filed: July 12, 2007
    Date of Patent: January 10, 2012
    Assignee: NEC Communication Systems, Ltd.
    Inventors: Akira Matsumoto, Tetsuya Ito, Hiroyuki Iizuka, Yuichiro Ezure
  • Patent number: 8045857
    Abstract: In an optical access network using an optical switching device, a 2×1 optical splitter in the uplink and downlink directions is eliminated to extend the transmission distance between the OLT and the ONU. An optical switching device includes a downlink optical switch element for switching a downlink optical signal sent by an OLT, an uplink optical switch element for switching an uplink optical signal sent by a plurality of ONU, an O/E for converting a downlink optical signal to a first electrical signal, an E/O for converting the first electrical signal to a downlink optical signal and inputting the downlink optical signal to the downlink optical element, an O/E for converting an uplink optical signal output from the uplink optical switch element to a second electrical signal, and an E/O for converting the second electrical signal to an uplink optical signal and sending the uplink optical signal to the OLT.
    Type: Grant
    Filed: December 19, 2006
    Date of Patent: October 25, 2011
    Assignee: NEC Communications Systems, Ltd.
    Inventors: Takumi Nomura, Hiromi Ueda, Kunitetsu Makino, Hiroaki Kurokawa, Toshinori Tsuboi, Hiroyuki Kasai, Hirokazu Kobayashi
  • Patent number: 8041377
    Abstract: A radio device is located far from other radio devices in a radio network system. The radio device determines a threshold WIth for detecting a strength equal to or more than the minimum strength of radio waves transmitted/received in a stable radio wave environment based on a plurality of reception signal strengths of Hello packets received from radio devices adjacent to the radio device. Then, if the number of radio devices adjacent to the radio device when the threshold WIth is introduced is less than a standard value (such as five), the radio device stores the adjacent radio devices in the neighbor list without introducing the threshold WIth, and then, maintains in the routing table the routing information of routes passing through the adjacent radio devices based on the neighbor list.
    Type: Grant
    Filed: September 27, 2007
    Date of Patent: October 18, 2011
    Assignees: NEC Communication Systems Ltd., Advanced Telecommunications Research Institute International
    Inventors: Satoko Itaya, Jun Hasegawa, Akio Hasegawa, Peter Davis, Tetsuya Ito, Akira Matsumoto, Naoto Kadowaki, Sadao Obana
  • Patent number: 8005005
    Abstract: An ON-OFF traffic characteristic can be analyzed in real time from a measurement value without requiring detailed data analysis which is performed using measurement values accumulated for a predetermined time period through a high-performance measurement apparatus. A packet length and a packet transfer time interval of a communication traffic are first measured, and a data transfer rate variance indicator is computed based on a relative entropy value between the measured packet transfer time interval and a packet transfer time interval in case of transferring at a constant transfer rate. A predetermined traffic characteristic value is at least approximately computed using the computed data transfer rate variance indicator.
    Type: Grant
    Filed: February 25, 2009
    Date of Patent: August 23, 2011
    Assignee: NEC Communication Systems, Ltd.
    Inventor: Tadashi Enomoto
  • Patent number: 8000714
    Abstract: An interference prediction apparatus capable of predicting a wireless channel in which channel interference occurs, measures a received signal strength for each wireless channel and predicts an interference area of the wireless channel in which channel interference occurs for each wireless channel on the basis of the received signal strength for each wireless channel.
    Type: Grant
    Filed: July 12, 2007
    Date of Patent: August 16, 2011
    Assignee: NEC Communications Systems, Ltd.
    Inventors: Akira Matsumoto, Tetsuya Ito
  • Patent number: 7991400
    Abstract: The use of a wireless interface is dynamically changeable according to connection states of stations belonging to access points. Therefore, limited wireless interfaces are efficiently utilized without requiring operation in which the user conducts a complex setting operation. First, connection states of stations belonging to access points are measured. Based on information of the connection states, the connection destination of a wireless connection unit of an access point under consideration is changed over between an access point and a station.
    Type: Grant
    Filed: July 9, 2007
    Date of Patent: August 2, 2011
    Assignee: NEC Communication Systems, Ltd.
    Inventors: Tetsuya Ito, Akira Matsumoto, Yuichiro Ezure, Hiroyuki Iizuka
  • Patent number: 7894363
    Abstract: A data transfer rate variance indicator having a small amount of calculation for each one packet and a small necessary amount of buffer (memory size), and representing a value suitable for traffic quality evaluation is to be used. Therefore, a packet transfer time interval is measured, and a data transfer rate variance indicator which is obtained based on a relative entropy value between the measured packet transfer time interval and a packet transfer time interval in a case where transfer is performed at a constant transfer rate is used for calculation.
    Type: Grant
    Filed: June 19, 2008
    Date of Patent: February 22, 2011
    Assignee: NEC Communication Systems, Ltd.
    Inventor: Tadashi Enomoto
  • Patent number: 7894840
    Abstract: Disconnection of communication is prevented and a connecting relation is maintained between radio devices even when a communication channel is dynamically switched. Accordingly, when a first radio device switches a communication channel used for radio communication with a second radio device, the first radio device firstly switches to a simultaneously-connectable channel capable of a simultaneous communication with an original channel, and then switches to a destination channel.
    Type: Grant
    Filed: July 9, 2007
    Date of Patent: February 22, 2011
    Assignees: NEC Communication Systems, Ltd., NEC Infrontia Corporation
    Inventors: Tetsuya Ito, Akira Matsumoto
  • Patent number: 7890112
    Abstract: The route maintenance unit outputs a period setting request to the period setting unit when the communication unit normally receives a Hello packet for the first time. The period setting unit sets a link connection confirmation period in response to the period setting request and outputs the set period to the route maintenance unit. The route maintenance unit maintains a radio link between the radio device in which the route maintenance unit is provided and an adjacent device upon receiving a data packet other than a Hello packet from the adjacent radio device even if a Hello packet is not received in the link connection confirmation period. Consequently, route disconnection or switching occurs less often.
    Type: Grant
    Filed: September 4, 2007
    Date of Patent: February 15, 2011
    Assignees: NEC Communication Systems, Ltd., Advanced Telecommunications Research Institute International
    Inventors: Tetsuya Ito, Jun Hasegawa, Satoko Itaya, Akira Matsumoto, Hiroyuki Iizuka, Yuichiro Ezure, Akio Hasegawa, Peter Davis, Naoto Kadowaki, Sadao Obana
  • Patent number: 7616899
    Abstract: To provide synchronizing methods, optical switch modules, center devices, remote devices, optical access systems, optical access networks, programs, and recording media in the optical access network which can give the connection start time of the upstream optical switching element of the optical switch module. To the optical switch module, ranging functions are provided and the center device OLU carries out ranging of the optical switch module OSM as is the case of ranging of the remote device ONU. The center device OLU transmits the difference between roundtrip time of the remote device ONU and roundtrip time of optical switch module OSM, which is the result of these rangings, to the optical switch module OSM, and the optical switch module OSM can obtain the contact start time of the upstream optical switching element by calculating the contact start time using the difference.
    Type: Grant
    Filed: March 3, 2006
    Date of Patent: November 10, 2009
    Assignee: NEC Communications Systems, Ltd.
    Inventors: Takumi Nomura, Hiromi Ueda, Kunitetsu Makino, Hiroyuki Kasai, Toshinori Tsuboi, Hiroaki Kurokawa, Hirokazu Kobayashi, Hiroyuki Endo
  • Patent number: 7577362
    Abstract: An optical access network method, an optical access network and an optical switch for an optical access network, capable of solving all the three problems in the conventional GE-PON: transmission distance problem, security problem and communication interference problem. The optical access network comprises an OLT, a plurality of ONUs and one or more stages of optical switches, which are connected one another. In the direction from the OLT to the ONU, each frame (packet) transmitted from the OLT to one of the ONUs is checked so that only the destination ONU specified in the frame (packet) is connected to the OLT. In the direction from the ONU to the OLT, a control message transmitted from the OLT to one of the ONUs is checked so that only one ONU which has been given a transmission allowance from the OLT is connected to the OLT with respect to each frame (packet).
    Type: Grant
    Filed: November 14, 2005
    Date of Patent: August 18, 2009
    Assignee: NEC Communication Systems Ltd.
    Inventors: Hiroyuki Kasai, Toshinori Tsuboi, Hiromi Ueda, Takumi Nomura, Hirokazu Kobayashi, Kunitetsu Makino, Hiroyuki Endo