Hitachi, Ltd.

Hitachi Computer Engineering Co., Ltd.

Kenichiro Orita

Hidehiko Jusa

Takaharu Aoyama

Tomoaki Ishifuji

Masaaki Shida

Hiroyuki Wada

Masato Hirai

Atsushi Anzai

A frequency-hopped mobile communication system is disclosed, in which a mobile wireless station automatically becomes a base station in accordance with the surrounding conditions, thereby automatically reconfiguring a communication network. A control frame is generated by at least one master station, and frequencies are hopped by a plurality of slave stations in accordance with the control frame. Each slave station switches the master thereof to be tracked, in accordance with the receiving conditions of the control frame and the relation between the control frame received from the master station and the status of the slave station and decides in which mode, master station or slave station, the slave station is to operate. The cells are thus automatically reconfigured.

Frequency-hopped wireless communication system and mobile wireless

In a wireless LAN system, each wireless terminal device determines whether or not the wireless terminal device has entered into a wireless LAN domain established by a base station, and if it has entered, transmits an entry terminal identification information update control frame including identification information of its own device to the base station at a predetermined time interval. The base station receives the entry terminal identification information update control frame from the wireless terminal device, stores in a storage the identification information of the wireless terminal device entered into the wireless LAN domain established by its own base station, and when it receives an information frame from a wired transmission line connected to its own base station, relay-transmits only the information frame to the wireless terminal device having the identification information thereof stored in the storage by referring the information stored in the storage.

Wireless LAN system, base station device and wireless terminal device

A transmission line fault detecting method and system use fault detectors capable of sending and receiving a fault locating frame of an arbitrary length for reliably detecting the location in the transmission line where the fault occurred. A number of such fault detectors are incorporated in a ring transmission system, wherein each detector sends and receives a fault locating frame including a first frame bounded by a starting delimiter and an ending delimiter, and a second frame following the first frame and containing other data bounded by an ending delimiter. The fault locating frame has a large frame length, preferably on the order of 4000 bytes. The first frame is formatted according to the communication protocol inherent to the transmission system. The present invention advantageously enables even a fault of less significance to be detected with high reliability.

Transmission path fault detecting method and system

In a LAN interconnecting apparatus having two transmitting and receiving sections connected to respective LANs, each of the transmitting and receiving sections can be set in either a first or a second operation mode by setting a register. The transmitting and receiving section copies and transfers relayed information frames in the first operation mode, but it does not in the second operation mode. The apparatus makes a unidirectional LAN interconnecting apparatus when one of the transmitting and receiving sections is set in the first operation mode and the other in the second operation mode, while it makes a bidirectional one when both of the transmitting and receiving sections are set in the first operation mode.

Growing community of inventors

Hadano, Japan

Kenichiro Orita