Communication system, communication device, and method for operating communication system

A communication device on a transmission side, which performs electric power line communication with a communication device on a reception side with an electric power line used as a transmission path,

• said communication device on the transmission side comprising:
• detection means for detecting zero crossing timing at regular intervals in a commercial power supply;
• and
• transmission means for transmitting an initial signal added with an error detection code in each zero crossing period including zero crossing timing while changing transmission timing within the zero crossing period, wherein
• said communication device on the reception side has
• error detecting means for performing error detection on each initial signal received in each zero crossing period based on the error detection code added to said each initial signal,
• specification means for specifying optimum communication timing out of a plurality of pieces of transmission timing within the zero crossing periods based on a result of error detection on said each initial signal, and
• transmission means for transmitting a response signal including timing information on said optimum communication timing,
• said communication device on the transmission side further has reception means for receiving said response signal, and
• the transmission means of said communication device on the transmission side transmits a transmission signal including actual data in said optimum communication timing within the zero crossing period, which is specified based on said timing information.

A communication device on a reception side, which performs electric power line communication with a communication device on a transmission side with an electric power line used as a transmission path, wherein

• said communication device on the transmission side comprising:
• detection means for detecting zero crossing timing at regular intervals in a commercial power supply, and
• transmission means for transmitting an initial signal added with an error detection code in each zero crossing period including zero crossing timing while changing transmission timing within the zero crossing period, and
• said communication device on the reception side has
• error detecting means for performing error detection on each initial signal received in each zero crossing period based on the error detection code added to said each initial signal;
• specification means for specifying optimum communication timing out of a plurality of pieces of transmission timing within the zero crossing periods based on a result of error detection on said each initial signal;
• and
• transmission means for transmitting a response signal including timing information on said optimum communication timing.

A method for operating a communication system, which includes a first communication device and a second communication device that performs electric power line communication with said first communication device with an electric power line used as a transmission path,

• said method comprising the steps of:
• a) detecting zero crossing timing at regular intervals in a commercial power supply in the first communication device;
• b) transmitting an initial signal added with an error detection code in each zero crossing period including zero crossing timing while changing transmission timing within the zero crossing period, in said first communication device;
• c) performing error detection on each initial signal received in each zero crossing period based on the error detection code added to said each initial signal in said second communication device;
• d) specifying optimum communication timing out of a plurality of pieces of transmission timing within said zero crossing period based on a result of error detection on said each initial signal in said second communication device;
• e) transmitting a response signal including timing information on said optimum communication timing in said second communication device;
• and
• f) transmitting a transmission signal that includes actual data in said optimum communication timing within the zero crossing period, which is specified based on said timing information included in said response signal in said first communication device.