Information transmission system and information transmission method, and, optical space transmission system and optical space transmission method

An information transmission method used for transmitting information from a sending apparatus to a receiving apparatus, said information transmission method comprising the steps of:

• selecting one of a first transmission mode and a second transmission mode,
• said sending apparatus demultiplexing an information signal into a first data signal and a second data signal that are different from each other, modulating said first data signal and said second data signal;
• controlling said sending apparatus such that said first data signal is transmitted to said receiving apparatus as a radio signal and said second data signal is transmitted to said receiving apparatus as an optical signal when said first transmission mode is selected;
• controlling said sending apparatus such that said information signal is transmitted to said receiving apparatus via a plurality of routes including a radio transmission route and an optical transmission route when said second transmission mode is selected;
• said receiving apparatus multiplexing said first data signal and said second data signal when said first transmission mode is selected;
• and
• said receiving apparatus diversity-combining said information signal which is transmitted via said plurality of routes when said second transmission mode is selected.

A sending apparatus comprising:

• a mode selection part configured to select one of a first transmission mode and a second transmission mode,
• a demultiplexer configured to separate an information signal into a first data signal and a second data signal that are different from each other;
• radio signal modulation parts configured to modulate said first data signal and said second data signal;
• a control part configured to control said sending apparatus such that said first data signal is transmitted as a radio signal and said second signal is transmitted as an optical signal when said first transmission mode is selected;
• said control part controlling said sending apparatus such that said information signal is transmitted via a plurality of routes including a radio transmission route and an optical transmission route when said second transmission mode is selected.

A receiving apparatus comprising:

• a radio signal receiver configured to receive a radio signal and output a first data signal;
• an optical signal receiver configured to receive an optical signal and output a second data signal;
• and
• a signal combining part configured to combine said first data signal and said second data signal, and regenerate an information signal,
• said receiving apparatus further comprising:
• a mode selection part configured to select one of a first transmission mode and a second transmission mode;
• wherein, when said first transmission mode is selected, said first signal and said second signal are different from each other and are multiplexed into an information signal, and, when said second transmission mode is selected, said first signal and said second signal are the same and are diversity-combined by said signal combining part.