| 摘要 |
PURPOSE: To solve a problem of secrecy of served information by decoding each 1st word received by a terminal station as detected transmission error information and a 2nd word function to be stored. CONSTITUTION: The communication network includes a central transmission reception station like a switch changeover device 1, which is connected to a plurality of terminal transmission reception stations like subscriber equipments 31 -3J (J=12) through the directivity of an optical fiber coupler 2. The coupler 2 is provided with a 1st port connected to the changeover device 1 through optical fibers 12 and a 2nd port (J=12). Then the 2nd port (J=12) is connected to the subscriber equipments 31 -3J via optical fibers 231 -23J (J=12). Packets are transmitted between the changeover device 1 and the subscriber equipments 31 -3J in the collective semi-duplex mode. For a 1st communication period, the changeover device 1 sends a coded reverse direction packet PD*, which is received by the subscriber equipments 31 -3J. |
