×

Optical line terminal and optical network unit

  • US 8,929,737 B2
  • Filed: 02/19/2010
  • Issued: 01/06/2015
  • Est. Priority Date: 02/24/2009
  • Status: Active Grant
First Claim
Patent Images

1. An optical line terminal in an optical network in which the optical line terminal (OLT) and an optical network unit (ONU) communicate with each other through an optical fiber transmission path, the OLT including:

  • an observing unit that observes information of an arrival interval of frames transmitted to the ONU or frames received from the ONU, an instantaneous bandwidth under use of a flow transmitted to the ONU or a flow received from the ONU, and a queue length of a queue temporarily storing the frames transmitted to the ONU or a queue temporarily storing the frames received from the ONU; and

    a calculating unit that dynamically determines a sleep time to be a period in which a sleep state where non-used functions of the ONU are stopped is maintained, on the basis of the information obtained by the observing unit,wherein a control signal to notify the ONU of a sleep state entering request and the sleep time is transmitted to the ONU immediately after communication with the ONU ends, after a predetermined time passes from when the communication with the ONU ends, or after a time determined on the basis of the information passes from when the communication with the ONU ends,wherein a maximum value and a minimum value are set for the sleep time, and the ONU is maintained in a normal state in the case of at least one of the case where the arrival interval of the frames obtained by the observing unit is smaller than a threshold value of the arrival interval of the frames, the case where the instantaneous bandwidth under use is greater than a threshold value of the instantaneous bandwidth under use, and the case where the queue length is greater than a threshold value of the queue length,wherein the ONU is entered into the sleep state where the arrival interval of the frames obtained by the observing unit is equal to or greater than the threshold value of the arrival interval of the frames, where the instantaneous bandwidth under use is equal to or smaller than the threshold value of the instantaneous bandwidth under use, or where the queue length is equal to or smaller than the threshold value of the queue length,wherein the sleep time is set to a value between the maximum value and the minimum value,wherein, when the arrival interval of the frames obtained by the observing unit is equal to or greater than the threshold value of the arrival interval of the frames, the sleep time is calculated using following equations;


    T1=Tmin+(Tmax−

    Tmin)*f(p)
    f(p)=(1−

    (Th1/p)) or
    f(p)=(p−

    Th
    1)/(Th1′



    Th1),T1 indicates the sleep time, Tmin indicates the minimum value of the sleep time, Tmax indicates the maximum value of the sleep time, Th1 indicates the threshold value of the arrival interval of the frames, p indicates the arrival interval of the frames, and Th1

    indicates the maximum threshold value of the arrival interval of the frames,wherein, when the instantaneous bandwidth under use obtained by the observing unit is equal to or smaller than the threshold value of the instantaneous bandwidth under use, the sleep time is calculated using following equations;


    T1=Tmin+(Tmax−

    Tmin)*f(B)
    f(B)=(1−

    (B/Th2)) or
    f(B)=(Th2

    B
    )/(Th2

    Th
    2′

    ),T1 indicates the sleep time, Tmin indicates the minimum value of the sleep time, Tmax indicates the maximum value of the sleep time, Th2 indicates the threshold value of the instantaneous bandwidth under use, B indicates the instantaneous bandwidth under use, and Th2

    indicates the minimum threshold value of the instantaneous bandwidth under use, andwherein, when the queue length obtained by the observing unit is equal to or smaller than the threshold value of the queue length, the sleep time is calculated using following equations;


    T1=Tmin+(Tmax−

    Tmin)*f(q)
    f(q)=(1−

    (q/Th3)) or
    f(q)=(Th3

    q
    )/(Th3

    Th
    3′

    ),T1 indicates the sleep time, Tmin indicates the minimum value of the sleep time, Tmax indicates the maximum value of the sleep time, Th3 indicates the threshold value of the queue length, q indicates the queue length, and Th3

    indicates the minimum threshold value of the queue length, andany one of the calculated sleep times is determined as the sleep time.

View all claims
  • 1 Assignment
Timeline View
Assignment View
    ×
    ×