Abstract: A data link transmission control method according to the present invention is a data link transmission control method of performing data link transmission control comprising automatic repeat request control for transmission/reception of a packet between a mobile station and a plurality of base stations, wherein when during connection with a first base station, the mobile station sends a request for connection with a second base station to the first base station, the first base station transfers data link transmission control information to the second base station.

Abstract: A communication control method used in a cellular mobile communication system in which each base station can radiate radio wave beams to a plurality of directions and each base station communicates with mobile stations by using the same frequency is provided in which the method includes the step of: controlling first timing at which a base station radiates a first radio wave beam such that the first timing is different from second timing at which another base station radiates a second radio wave beam which may cause interference with the first radio wave beam.

Abstract: An information transmission system for transmitting information from a sending apparatus to a receiving apparatus is provided. The information transmission system includes: a sending apparatus for modulating an information signal, generating a plurality of signals including an optical signal from the information signal which is modulated, and transmitting the plurality of signals via a plurality of routes; and a receiving apparatus for receiving the plurality of signals from the sending apparatus, diversity-combining the plurality of signals, and outputting the information signal, in which the plurality of signals are a plurality of optical signals or signals including a radio signal.

Abstract: In transmitting/receiving optical beams including optical signals via a space transmission path between an optical transmitting apparatus and an optical receiving apparatus, a degree of spread of the optical beam emitted from the optical transmitting apparatus to the-optical receiving apparatus is varied according to a predetermined condition.

Abstract: When a signal is sent from a wireless base station 3-1, a wireless modem 10-1 converts the signal to a signal of a unified transmission form. The switch 11-1 switches the signal to one of wireless transceivers 12-1, 12-2 and the optical transceiver 13-1. The wireless transceiver 12-1 or 12-2 sends the signal to a control station 4 or a wireless base station 3-3 via a wireless circuit 20. The optical transceiver 13-1 converts the signal into an optical signal and sends the optical signal to a wireless base station 3-2 via an optical fiber circuit 30.