Mitsubishi Materials Corporation

Akira Shibuno

Kenzo Nakamura

Tumoru Nagira

Kenichiro Hosobuchi

A communication system and a communication method arranged to obtain a diversity effect in mobile communication, to reduce the influence of multipath interference, fading or the like, to perform comparatively simple information communication such as message communication with improved reliability, and to achieve effective utilization of frequencies. A plurality of base stations having receivers are provided around an urban area within base station zones. The base stations repeatedly transmit the same message data. Receiving repeaters are provided in the urban area and small or medium suburban zones. Each receiving repeater relays a signal from a small mobile terminal via an Internet network if the output level of the mobile terminal is so low that direct transmission to one of the base stations is impossible. A 25 kHz frequency band is divided into four narrower bands of 6.25 kHz in one of the embodiments. Of frequencies f , f , f , and f in these bands, frequencies f to f are used for &ldquo;down data transmission&rdquo; from the base stations to a mobile terminal while f is used for &ldquo;up data transmission&rdquo; from the mobile station to one or more of the base stations.

Communication system and communication method with diversity features

A method of checking and acknowledging reception of a message in a two-way radio communication system without causing a reduction in the efficiency of processing the message, a storage medium on which a reception checking and acknowledging program is stored for use in the two-way radio communication system, and a two-way radio communication system and a base station for use in the two-way radio communication system is provided. If message data transmitted by a terminal device is received by a base station via a relay station and an Internet network, the base station generates reception acknowledgment data and transmits it in such a manner that when downstream message data is transmitted toward a plurality of terminal devices, the above-described reception acknowledgment data is added to the downstream message data and the resultant data is transmitted to the plurality of terminal devices.

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Omiya, Japan

Akira Shibuno