Hitachi, Ltd.

Hitachi Communication Technologies, Ltd.

Ryosuke Kurata

Koichi Okita

Tohru Kazawa

Kenji Yamazaki

Hideaki Ishii

Eiichiro Takizawa

Masaaki Yano

Daiho Kasai

Shuhei Takahashi

Taiki Nema

Kenta Komiya

A zero traffic state that is a non-communication state derived from any fault is discriminated from a no-operation state derived from, power discontinuity, and a communication device that is in the zero traffic state is efficiently sensed in consideration of a zero traffic period that is normally observed in a certain installation place or use environment. A network monitoring device cyclically notifies a maintenance person of a communication device, for which a time difference between a final access time and a finally passed traffic generation time exceeds a threshold calculated by multiplying a previously observed maximum, value of the time difference between the final access time and the finally passed traffic generation time by a coefficient that is a safety factory as a device that is In a zero traffic suspected state.

Network monitoring device

A base station control portionselects one or plural signals from signals received by plural settable communication paths in accordance with the state of the wave. A wireless communication apparatuscommunicates with a wireless terminaland a wired communication network. When the wireless communication apparatusreceives a request for upgrading software from a network management device, the wireless communication apparatuscontrols the state of the transmission wave of a wireless interface so as to switch a communication path in which communication services are being provided to another wireless communication apparatuswithout blackouts, rewrites the set software to software having been received through a wired interface in advance, returns the state of the transmission wave of the wireless interface and upgrades software without blackouts of the supply of communication services to the wireless terminal

Wireless communication apparatus, wireless communication network and software upgrading method

An optical network system including an OLT and ONUs is provided that can prevent the loss of a multicast signal. When receiving an encryption key generation request from the OLT, the ONU generates an encryption key, and transmits the generated encryption key to the OLT. When receiving a notice of timing from the OLT, the ONU updates the encryption key of a belonging group. When receiving a report message from a STB through the ONU, the OLT analyzes the report message, stores a group that the STB belongs to as well as the ONU in a second table, and transmits the encryption key generation request to the ONU. When receiving the encryption key from the ONU, the OLT further stores the encryption key in the second table, and transmits to the ONU a notice of the timing in which the encryption key is valid.

Optical network system and method of changing encryption keys

A base station control portion selects one or multiple signals in accordance with the state of radio waves from signals received through multiple communication paths. A wireless communication apparatus communicates with a wireless terminal and a wired communication network at multiple frequencies. In response to a request for software upgrading from a network management device, the wireless communication apparatus selects one frequency, controls the state of transmission waves of a wireless interface such that a communication path in which a communication service is being provided can be switched to another communication network without interruption, rewrites software for each wireless interface to software received through a wired interface in advance, and returns the state of transmission waves of the wireless interface. Thus, the software can be upgraded without blackouts of the communication service to the wireless terminal.

A network management apparatus inputs a plurality of work dates and time periods to update software in a base station. The apparatus obtains an n-week average of the numbers of connection calls during each of the input time periods for each day of the week, based on statistical information about connection with a wireless terminal in each base station. The apparatus obtains an m-month average of the numbers of connection calls during each of the input time periods for each date, based on the statistical information. The apparatus calculates, for each of the time periods for a work date, an average or a weighted average of the n-week average and the m-month average to obtain a degree of impact upon a communication service. A processing section selects a work date and a time period having the minimum degree of impact and updates the software.

Network management apparatus and method of selecting base station for software update

Congestion caused by a large number of IGMP requests sent from set top boxes at channel switching is prevented in an optical line terminal (OLT). An IGMP processing section in the OLT has a delayed data generation threshold and a delayed data transmission threshold. When the number of ONTS participating in a multicast group is increased, the OLT generates a delayed multicast group for video data. The delayed multicast group having a few second delay accommodates a new user. With this, the end time of a highly popular program and a commercial start time are shifted among users to prevent, in the OLT, congestion caused by IGMP requests sent for channel switching at an identical time point.

Communication system, optical line terminal, and congestion control method

A network system automatically distributes management information to allow immediate monitoring. In the network system, the DHCP server of a network-information management server assigns information to a network-information management table when receiving an assignment request of IP information and network management information from a client. The DHCP client of the client obtains the IP information and the network management information from the DHCP server. The SNMP agent of the client reports to a monitoring server that the network management information has been set. The SNMP manager of the monitoring server determines that the network management information has been set, the monitoring control section of the monitoring server records information of the client in a monitoring control table, and starts monitoring the client.

Network system

A neighbor sector is automatically set to effectively perform soft handover. A base station corresponding to a first sector to communicate with a wireless terminal and a base station corresponding to a second sector to start communication with the wireless terminal due to movement of the wireless terminal or the like transmit a terminal identifier acquired from the wireless terminal, a time and a sector identifier to a base station control part (control part in the following). The control part successively stores the received sector identifier into a table correspondingly to the terminal identifier and the time received from the base station. Besides, the control part refers to the table, judges whether different sector identifiers are stored in a previously determined time range, regards a pair of the two different sector identifiers as neighbor sector candidates and counts the number of times they are regarded as the neighbor sector candidates. With respect to the neighbor sector candidates in which the counted number of times is a threshold or more, the control part transmits, to the base station corresponding to one sector of the neighbor sector candidates, a change request including the neighbor sector information concerning the other sector.

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Yokohama, Japan

Ryosuke Kurata