Delay adjustment unit and method, optical network unit, and communication system

An optical network unit, coupled to an optical access network system, which transmits upstream data composed of a plurality of upstream cells after making a delay adjustment thereto, comprising:

• downstream receiving means for receiving control information on which upstream cells are granted or not granted, together with an equalization delay update request that requests the optical network unit to update an equalization delay parameter being held therein;
• delay adjustment control means for controlling delay times of the upstream cells as specified in the control information, by determining upon receipt of the equalization delay update request whether a subsequent upstream time slot is granted or not granted and then activating the updated equalization delay parameter from the next granted upstream time slot after a non-granted upstream time slot is found;
• and
• upstream transmission means for transmitting the upstream cells with the adjusted delay times.

A communication system which transports a data signal after making delay adjustments, comprising:

• (a) an optical line terminal comprising:
• downstream data producing means for producing downstream data containing control information on which upstream cells are granted or not granted, together with an equalization delay update request that requests an update of an equalization delay parameter being held in a downstream device, and
• downstream transmission means for transmitting the produced downstream data;
• and
• (b) an optical network unit, disposed as the downstream device, comprising:
• downstream receiving means for receiving the downstream data,
• delay adjustment control means for controlling delay times of the upstream cells as specified in the control information, by determining upon receipt of the equalization delay update request whether a subsequent upstream time slot is granted or not granted and then activating the updated equalization delay parameter from the next granted upstream time slot after a non-granted upstream time slot is found, and
• upstream transmission means for transmitting the upstream cells with the adjusted delay times.

A network unit, coupled to an access network system, which transmits upstream data composed of a plurality of upstream cells after making a delay adjustment thereto, comprising:

• downstream receiving means for receiving control information on which upstream cells are granted or not granted, together with an equalization delay update request that requests the network unit to update an equalization delay parameter being held therein;
• delay adjustment control means for controlling delay times of the upstream cells as specified in the control information, by determining upon receipt of the equalization delay update request whether a subsequent upstream time slot is granted or not granted and then activating the updated equalization delay parameter from the next granted upstream time slot after a non-granted upstream time slot is found;
• and
• upstream transmission means for transmitting the upstream cells with the adjusted delay times.

A delay adjustment unit which performs delay adjustments, comprising:

• receiving means for receiving information about a delay parameter;
• delay adjustment control means for controlling a delay time of a data signal to be transmitted, based on the delay parameter, by determining, upon receipt of the information, whether a subsequent data signal to be transmitted is granted or not granted and then activating an updated delay time, based upon the received information, from the next granted data signal to be transmitted after a non-granted data signal is found;
• and
• transmission means for transmitting the data signal with the adjusted delay time.

A delay adjustment method which transmits upstream data composed of a plurality of upstream cells after making a delay adjustment thereto, comprising the steps of:

• receiving downstream data containing control information on whether the transmission of each upstream cell is granted or not granted;
• when an equalization delay update request that requests an update of an equalization delay parameter is received, controlling delay times of the upstream cells as specified in the control information, by determining upon receipt of the equalization delay update request whether a subsequent upstream time slot is granted or not granted and then activating the updated equalization delay parameter from the next granted upstream time slot after a non-granted upstream time slot is found;
• and
• sending upstream data with the adjusted delay times.