Method of Recovery From Sleep State of an Onu in a Pon System Capable of Power Saving

A communication system that comprises at least one terminal unit and a control unit and exchanges data between the terminal unit and the control unit,

• wherein the terminal unit includes:
• a reception section that receives a frame transmitted from the control unit;
• a transmission section that transmits a frame to the control unit;
• a control circuit that processes the frame;
• and
• a sleep control circuit that enables a power-saving state for at least one of the terminal units;
• wherein the control unit includes:
• a reception section that receives a frame transmitted from the terminal unit;
• a transmission section that transmits a frame to the terminal unit;
• and
• a control circuit that processes the frame;
• wherein the control circuit of the control unit cyclically allocates, to the power-saving terminal unit, a band for the terminal to transmit a sleep cancel report to the control unit and uses a transmission section of the control unit to cyclically transmit a control frame containing allocation information about the band to the power-saving terminal unit.