Patents by Inventor Yoshihiro Ashi
Yoshihiro Ashi 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).
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Publication number: 20120224488Abstract: A method carrying out connectivity monitoring of an entire network by: transmitting a CCM frame in which the transmission source is set to a multicast MAC address, from a higher level side (center side) terminating device to a plurality of lower level side (base point side) terminating devices; transmitting a CCM frame in which a unicast MAC address is set, from the lower level side terminating devices to the higher level side terminating device; transmitting a CCM frame in which a multicast MAC address is set, from a controller to the higher level side terminating device or the lower level side terminating devices; and transmitting a CCM frame in which a unicast MAC address is set, from the higher level side terminating device or the lower level side terminating devices to the controller.Type: ApplicationFiled: February 9, 2012Publication date: September 6, 2012Inventors: Masao NIIBE, Akihiko Tsuchiya, Takayuki Kanno, Yoshihiro Ashi
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Publication number: 20120219006Abstract: An interconnection between fully synchronous networks and next-generation frame communications networks is disclosed. A means of bidirectional frame format conversion between a synchronous multiplexing system and a logical multiplexing system is provided, along with a method of transmitting data between different networks on a path as if it were being transmitted in the same network. Further, when converting network control information in an STM network into data suitable for a packet network, even across the boundary of a synchronous multiplexing system and a logical multiplexing system, a unified communication management means is provided over the whole path.Type: ApplicationFiled: May 7, 2012Publication date: August 30, 2012Applicant: Hitachi, Ltd.Inventors: Masahiko MIZUTANI, Yoshihiro Ashi, Masayuki Takase, Atsushi Iwamura, Akihiko Tanaka, Hideki Endo, Tohru Kazawa
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Patent number: 8254780Abstract: In a passive optical network system, a parent station includes a reception circuit that receives an optical signal from each of child stations using a threshold used to identify if the optical signal is 0 or 1; a bandwidth setting unit that determines a time at which each child station sends an optical signal; a storage unit that stores thresholds and intensities of optical signals received from the child stations; and a control unit that sets a threshold, stored corresponding to a sending time, in the reception circuit to control a reception of an optical signal. The control unit has a function that compares an intensity of a signal received from each child station at an optical signal reception time with information stored in the storage unit to detect and determine a fault in the child station or in the optical fiber connected to the child station.Type: GrantFiled: February 26, 2009Date of Patent: August 28, 2012Assignee: Hitachi, Ltd.Inventors: Masahiko Mizutani, Yusuke Yajima, Yoshihiro Ashi
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Patent number: 8224135Abstract: In a PON system, an OLT periodically transmits a channel resource information block specifying a carrier wavelength and a spreading code on a first downstream channel to which a spread-spectrum spreader having a first spreading code is applied; one of ONUs receives the channel resource information block with a spread-spectrum despreader having the first spreading code and transmits a connection request to the OLT, using the carrier wavelength and the spreading code specified by the channel resource information block; the OLT having received the connection request transmits a new channel resource information block specifying a carrier wavelength and a spreading code to be used on an upstream data channel to the requester ONU through the first channel; and the requester ONU transmits data, using the carrier wavelength and the spreading code specified by the new channel resource information block.Type: GrantFiled: February 12, 2010Date of Patent: July 17, 2012Assignee: Hitachi, Ltd.Inventors: Masahiko Mizutani, Toshiki Sugawara, Tohru Kazawa, Yoshihiro Ashi
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Patent number: 8204168Abstract: A bit synchronization circuit comprising an initial phase determining unit for rapidly determining, during a period of receiving a preamble of burst data, a clock with a phase synchronized with received burst data from among multi-phase clocks having the same frequency as an internal reference clock and a phase tracking unit for modifying the synchronized phase clock responsive to phase variation of received data during a period of receiving a payload of burst data by taking the synchronized phase clock determined by the initial phase determining unit as an initial phase. The bit synchronization circuit retimes burst data with a data retiming clock having a predetermined phase relation with the synchronized phase clock and outputs the burst data in synchronization with the internal reference clock.Type: GrantFiled: January 7, 2009Date of Patent: June 19, 2012Assignee: Hitachi, Ltd.Inventors: Yusuke Yajima, Tohru Kazawa, Yoshihiro Ashi
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Patent number: 8189571Abstract: An interconnection between fully synchronous networks and next-generation frame communications networks is disclosed. A means of bidirectional frame format conversion between a synchronous multiplexing system and a logical multiplexing system is provided, along with a method of transmitting data between different networks on a path as if it were being transmitted in the same network. Further, when converting network control information in an STM network into data suitable for a packet network, even across the boundary of a synchronous multiplexing system and a logical multiplexing system, a unified communication management means is provided over the whole path.Type: GrantFiled: January 26, 2006Date of Patent: May 29, 2012Assignee: Hitachi, Ltd.Inventors: Masahiko Mizutani, Yoshihiro Ashi, Masayuki Takase, Atsushi Iwamura, Akihiko Tanaka, Hideki Endo, Tohru Kazawa
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Publication number: 20120127877Abstract: Packet transfer device and method have both a processing procedure for uninterruptible-switching desiring packets and a processing procedure for low-delay desiring packets, and process each user packet according to a desired one of the processing procedures. The uninterruptible-switching desiring packets are set to be in phase by a delay unit and written into an uninterruptible-switching memory. The low-delay desiring packets are written into a low-delay memory without passing trough the delay unit, that is, without being delayed. A read-out controller reads out a packet from the uninterruptible-switching memory. When the read-out packet is an uninterruptible-switching desiring packet, the packet is directly output, and when the read-out packet is a low-delay desiring packet, the packet is discarded, and a low-delay desiring packet is read out from the low-delay memory and output.Type: ApplicationFiled: November 22, 2011Publication date: May 24, 2012Applicant: HITACHI, LTD.Inventors: Kazuhiro WATANABE, Yoshihiro ASHI, Takayuki KANNO, Masayuki TAKASE
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Patent number: 8169895Abstract: The invention realizes defect indication on a multipoint logical path and switching of the logical path using a transfer protocol of configuring a logical path in a ring network. A working path and a backup path are set up where each transmits a frame from a transmitting end node to multicast receiving end nodes, forwards the frame to the transmitting end node and terminates it at the transmitting end node after going around the ring. Any node detecting a defect transmits a forward defect indication frame to a multipoint logical path in which the defect occurs. The transmitting end node receiving the forward defect indication frame halts the use of the notified multipoint logical path, and transmits a frame in another path where the forward defect indication frame is not received. When received from both multipoint logical paths, the transmitting end node copies the frame and forwards them to both paths.Type: GrantFiled: February 8, 2007Date of Patent: May 1, 2012Assignee: Hitachi, Ltd.Inventors: Masayuki Takase, Kenichi Sakamoto, Masahiko Mizutani, Hideki Endo, Yoshihiro Ashi, Takayuki Kanno, Nobuyuki Yamamoto
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Publication number: 20120027023Abstract: When multiple SDH/SONET frame are accumulated and then lower-order path information removed from multiple frames is multiplexed into the same packet to achieve better transmission efficiency during packetization, the delay for accumulating increases. Disclosed is a transmission device that packetizes an SDH/SONET lower-order path with timing which is an integer factor of 1 cycle of the SDH frame. In this case, the destination loads the same multiple lower-order path in one packet. The result is that delay time accompanying lower-order path packetization is kept to less than the time of 1 cycle of the SDH frame, and the efficiency with which lower-order paths are accommodated in packets is further increased. The result is that improved transmission efficiency is realized.Type: ApplicationFiled: November 14, 2008Publication date: February 2, 2012Inventors: Yoshio Nogi, Masatoshi Shibasaki, Naohiro Sakakida, Yoshihiro Ashi, Kazutaka Sakai
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Patent number: 8098678Abstract: Disclosed herewith is a PON system and a bandwidth controlling method capable of controlling congestion with use of an upstream bandwidth in a PON section efficiently when congestion occurs in a gateway (GW) connected to an OLT. An OLT connected to a plurality of ONUs through a passive optical network (PON) and to a gateway (GW) through a communication line, when receiving a congestion occurrence notice indicating a congestion occurred output number from a GW, identifies the identifier of the ONU that is using a GW output line having the congestion output port number and shifts the bandwidth controlling of the PON section in a normal mode for allocating a bandwidth to each ONU normally to that in a bandwidth suppression mode for allocating a congestion time allowable bandwidth that is less than the current bandwidth to the ONU having the identified ONU identifier and a bandwidth to each of other ONUs according to its transmission queue length.Type: GrantFiled: October 2, 2009Date of Patent: January 17, 2012Assignee: Hitachi, Ltd.Inventors: Hideki Endo, Masahiko Mizutani, Masayuki Takase, Kenichi Sakamoto, Yoshihiro Ashi, Takayuki Kanno, Nobuyuki Yamamoto
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Patent number: 8089865Abstract: Provided is a multicast path management method for a connectionless communication. Also provided is a path protection function which is effective when a path has failed. A network is formed by a trunk and a branch path. The multicast path is managed by end-to-end and when a failure has occurred, an instruction is issued from the apex of the multicast tree to respective end-to-end paths so as to switch from the currently used channel to a backup path. Thus, upon failure, an individual path protection can be performed without affecting other parts of the tree to which the same multicast flow as the defective path is distributed or the distribution state of the multicast flow.Type: GrantFiled: August 4, 2006Date of Patent: January 3, 2012Assignee: Hitachi, Ltd.Inventors: Masahiko Mizutani, Atsushi Iwamura, Yoshihiro Ashi, Masayuki Takase, Hideki Endo
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Publication number: 20110268435Abstract: Switching process at the occurrence of a path trouble is performed more quickly to reduce the number of packet discards during a traffic transition from a currently used system path to a standby system path within a section to be protected. An OLT (210-W) refers to the DBA information of a PON section and, if receiving no CCM frame at a timing at which the same should be received, then determines that some trouble has occurred on the path (S801) and transmits, to an OAM-compliant NE (200-Z), an application-for-switching frame (1501) to notify the OAM-compliant NE (200-Z) of the abnormal condition. The OAM-compliant NE (200-Z) monitors the occurrence of the trouble within the PON section nearly in real time, starts a switching process (S802) and generates and transmits a standby-system delivery request (321) (S302, S803). An OAM-compliant NE (200-A) switches the communication path to the standby-system passing through an OLT (210-P).Type: ApplicationFiled: January 13, 2009Publication date: November 3, 2011Inventors: Masahiko Mizutani, Yusuke Yajima, Nobuyuki Yamamoto, Yoshihiro Ashi
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Patent number: 7962037Abstract: Provided is an ONU that suppresses transmission of a useless multicast control message to a PON section and enables a communication bandwidth of the PON section to be effectively used. The ONU of the PON system has a multicast group management table that shows a correspondence between a multicast group identifier and an address of a user terminal participating in a multicast group. When the ONU receives a request message of participation in the multicast group from the user terminal, the ONU registers the correspondence between the multicast group identifier indicated by the received message and the user terminal address. A new received message is deleted without being sent to the OLT if another user terminal address is registered already, along with a correspondence with the same multicast group identifier, in the multicast group management table.Type: GrantFiled: November 19, 2009Date of Patent: June 14, 2011Assignee: Hitachi, Ltd.Inventors: Masahiko Mizutani, Takeshi Shibata, Tohru Kazawa, Yoshihiro Ashi, Masanobu Kobayashi, Masayuki Takase
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Publication number: 20110096794Abstract: A packet transfer apparatus connects two networks of different protocols. The packet transfer apparatus, connected to a first communication network and a second communication network, performs the steps of: storing first destination correspondence information; receiving a packet of the first communication protocol; based on the first destination correspondence information, determining destination information of a packet of the second communication protocol corresponding to destination information of the received packet of the first communication protocol; generating the header of the packet of the second communication protocol, based on the determined destination information of the packet of the second communication protocol; converting the received one or more packets of the first communication protocol into one or more packets of the third communication protocol; and adding the generated header of the packet of the second communication protocol to the packets of the third communication protocol.Type: ApplicationFiled: December 30, 2010Publication date: April 28, 2011Inventors: Masayuki Takase, Hideki Endo, Takayuki Kanno, Akihiko Tanaka, Yoshihiro Ashi, Nobuyuki Yamamoto
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Patent number: 7908390Abstract: A packet forwarding apparatus and network system for providing different types of bandwidth control services to the user; in which a packet forwarding apparatus for transferring data comprises an interface unit for sending and receiving packets, and a traffic shaper for controlling the packet transmission timing and a packet switch for sending an output to the interface unit as the destination of the received packet; and the traffic shaper uses a token bucket algorithm when transmitting a packet to guarantee the minimum frame rate, and uses a leaky bucket algorithm when limiting the peak frame rate.Type: GrantFiled: January 30, 2006Date of Patent: March 15, 2011Assignee: Hitachi, Ltd.Inventors: Masayuki Takase, Yoshihiro Ashi, Masahiko Mizutani, Tohru Kazawa, Kenichi Sakamoto, Taishi Shinagawa
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Patent number: 7876778Abstract: A packet transfer apparatus connects two networks of different protocols. The packet transfer apparatus, connected to a first communication network and a second communication network, performs the steps of: storing first destination correspondence information; receiving a packet of the first communication protocol; based on the first destination correspondence information, determining destination information of a packet of the second communication protocol corresponding to destination information of the received packet of the first communication protocol; generating the header of the packet of the second communication protocol, based on the determined destination information of the packet of the second communication protocol; converting the received one or more packets of the first communication protocol into one or more packets of the third communication protocol; and adding the generated header of the packet of the second communication protocol to the packets of the third communication protocol.Type: GrantFiled: March 12, 2008Date of Patent: January 25, 2011Assignee: Hitachi, Ltd.Inventors: Masayuki Takase, Hideki Endo, Takayuki Kanno, Akihiko Tanaka, Yoshihiro Ashi, Nobuyuki Yamamoto
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Publication number: 20100226244Abstract: Provided is a multicast path management method for a connectionless communication. Also provided is a path protection function which is effective when a path has failed. A network is formed by a trunk and a branch path. The multicast path is managed by end-to-end and when a failure has occurred, an instruction is issued from the apex of the multicast tree to respective end-to-end paths so as to switch from the currently used channel to a backup path. Thus, upon failure, an individual path protection can be performed without affecting other parts of the tree to which the same multicast flow as the defective path is distributed or the distribution state of the multicast flow.Type: ApplicationFiled: August 4, 2006Publication date: September 9, 2010Applicant: HITACHI COMMUNICATION TECHNOLOGIES, LTD.Inventors: Masahiko Mizutani, Atsushi Iwamura, Yoshihiro Ashi, Masayuki Takase, Hideki Endo
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Patent number: 7773880Abstract: An optical access system capable of avoiding cutoffs or interruption in the periodically transmitted signals that occur during the ranging time is provided. A first method to avoid signal cutoffs is to stop periodic transmit signals at the transmitter during the ranging period, and transmit all the periodic transmit signals together when the ranging ends, and buffer the signals at the receiver to prepare for ranging. A second method is to fix definite periods ahead of time for performing ranging, then cluster the multiple periodic transmit signals together in sets at the transmitter and send them, and then disassemble those sets back into signals at the receiver. The transmitting and receiving is then controlled so that the transmit periods do not overlap with the ranging periods. In this way an optical access system is provided that can send and receive signals requiring periodic transmissions without interruption even during ranging operation.Type: GrantFiled: March 25, 2008Date of Patent: August 10, 2010Assignee: Hitachi, Ltd.Inventors: Kenichi Sakamoto, Yoshihiro Ashi, Tohru Kazawa, Ryosuke Nishino, Masayuki Takase, Masahiko Mizutani
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Publication number: 20100158527Abstract: In a PON system, an OLT periodically transmits a channel resource information block specifying a carrier wavelength and a spreading code on a first downstream channel to which a spread-spectrum spreader having a first spreading code is applied; one of ONUs receives the channel resource information block with a spread-spectrum despreader having the first spreading code and transmits a connection request to the OLT, using the carrier wavelength and the spreading code specified by the channel resource information block; the OLT having received the connection request transmits a new channel resource information block specifying a carrier wavelength and a spreading code to be used on an upstream data channel to the requester ONU through the first channel; and the requester ONU transmits data, using the carrier wavelength and the spreading code specified by the new channel resource information block.Type: ApplicationFiled: February 12, 2010Publication date: June 24, 2010Applicant: Hitachi, Ltd.Inventors: Masahiko Mizutani, Toshiki Sugawara, Tohru Kazawa, Yoshihiro Ashi
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Publication number: 20100150554Abstract: A PON system capable of utilizing the bandwidth of an optical transmission channel in the PON section. In a PON system including an OLT and a plurality of ONUs, the OLT has: a downstream frame processing unit that removes at least part of the header information in a layer 2 header from a downstream frame received from a wide area network, and converts the remaining frame portion into a frame having a header specific to the PON section; and a downstream frame processing unit that extracts a downstream frame portion to be transferred to a user terminal, from a received frame from a PON, and adds the layer 2 header information deleted in the OLT.Type: ApplicationFiled: February 16, 2010Publication date: June 17, 2010Inventors: Masahiko Mizutani, Takeshi Shibata, Tohru Kazawa, Yoshihiro Ashi, Masanobu Kobayashi, Hideki Endo