JP2643832B2 - Propagation delay measurement method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a PDS optical subscriber system and, more particularly, to a method for measuring a propagation delay between a subscriber unit and a center unit.

[0002]

2. Description of the Related Art PDS (Passive Double)
(Star) The optical subscriber system is composed of a center device and a subscriber device. The center-side device and the subscriber-side device usually have a point-multi connection configuration using an optical fiber via a star coupler. Since the connection distances between the center unit and the subscriber unit are different from each other, each time a new subscriber unit is connected, the propagation delay due to the distance is measured, and all the center units are connected. The intra-device delay amount is assigned to the subscriber device so that the response time with the subscriber device looks the same. Therefore, it is necessary to measure a delay amount in order to determine a delay amount to be allocated.

[0003] In a conventional method of measuring the amount of propagation delay between a subscriber unit and a center unit in a PDS subscriber system, as shown in FIG. A plurality of subscriber units connected to the center unit 11 via a star coupler 13 are provided with a delay amount measurement command detection circuit 2 and a delay amount measurement cell transmission circuit, respectively. 3 and
The delay amount is measured as follows.

[0006] First, a cell including a delay amount measurement command and a subscriber unit under test identification number is transmitted to the subscriber unit 12 from the delay amount measurement command transmission circuit 1 of the center unit 11. The delay amount measurement command detecting circuit 2 of the subscriber side device to be measured confirms the identification number addressed to itself and the delay measurement command, and then the delay amount measurement cell transmission circuit 3 transmits the delay value measurement cell to the center side device 11. I do.

The center side apparatus 11 receives the delay value measurement cell by the delay amount measurement cell detection circuit 4 and determines the propagation delay amount from the transmission of the cell by the delay amount measurement command transmission circuit 1 to the reception thereof. Measure, set the delay value of the difference between the maximum delay amount and the actual delay amount among the plurality of subscriber units in the subscriber unit, the subscriber unit always receives the cell from the center unit, The cell is transmitted to the center device with the delay value. As a result, processing can be performed from the center-side device to all the subscriber-side devices with the same delay amount.

[0006]

In the conventional method of measuring the amount of propagation delay between the center unit and the subscriber unit, the state of the subscriber unit is an unstable state immediately after power-on or a stable state. If the delay measurement is performed from the center device during a time when the cell transmission timing from the subscriber device is not stable because the device is unknown from the center device, an incorrect delay value is set, and In some cases, a delay measurement must be performed.

SUMMARY OF THE INVENTION It is an object of the present invention to enable a center device to measure a propagation delay amount in a stable state of a subscriber device and to provide an accurate delay value to the subscriber device.

[0008]

SUMMARY OF THE INVENTION The present invention relates to a method for measuring the amount of propagation delay by transmitting and receiving cells between a subscriber unit and a center unit in a PDS optical subscriber system. The user-side device has a timer that measures the time from when the power switch is turned on, and delays the unstable state information during the time until this timer times out.
An unstable state information transmitting circuit for transmitting the superposed state information to the measuring cell , wherein the center apparatus detects an unstable state information from the subscriber side apparatus; The output of the information detection circuit allows the delay
A propagation delay amount measurement circuit that controls the discard of the file.
It is characterized by the following.

[0009]

The timer starts when the power switch is turned on, and times out when the subscriber unit reaches a stable state. Therefore, when the subscriber unit returns the delay amount measurement cell based on the delay amount measurement command from the center side device, if the timer has not timed out, the unstable state information sending circuit sends the unstable state information, The data is superimposed on the cell and sent to the center device.

In the center device, when the unstable state information detecting circuit detects the unstable state, the propagation delay amount measuring circuit discards the cell transmitted from the subscriber side device. Therefore, the propagation delay amount measuring circuit receives only the cells returned in the normal response time. Thus, the center device can measure the propagation delay amount of each subscriber device in a stable state.

[0011]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. The center device 8 installed in the office is connected to a plurality of subscriber devices 9 via a star coupler 10.

The center-side device includes a delay amount measurement command transmission circuit 1, a delay amount measurement cell detection circuit (propagation delay amount measurement circuit) 4, and an unstable state for detecting unstable state information from the subscriber side device 9. And a state information detection circuit 7. The subscriber unit 9 includes a delay amount measurement command detection circuit 2, a delay amount measurement cell transmission circuit 3, and a timer 6 that measures time since the power switch is turned on and times out when the subscriber side device becomes stable. And an unstable state information sending circuit 5 for sending the unstable state information until the timer times out.

In the PDS subscriber system described above, since each subscriber unit 9 is installed in a different user's house, the distance between the center unit and the subscriber unit when the power of the subscriber unit is turned on, That is, it is necessary to measure the propagation delay amount individually.

The measurement of the amount of propagation delay is performed as follows. FIG. 2 is a flowchart showing the operation of the center device,
FIG. 3 is a flowchart showing the operation of the subscriber unit.

The delay amount measurement command sending circuit 1 of the center unit 8 sends a cell for delay measurement to the subscriber unit 9 (FIG. 2, step S1). To this cell, a cell containing the delay amount measurement command and the measured subscriber unit identification number is transmitted.

The delay amount measuring instruction detecting circuit 2 of the subscriber unit 9 to be measured confirms the identification number and the delay measuring instruction addressed to itself (FIG. 3, step P1), and then the delay amount measuring cell transmitting circuit 3 The cell for delay value measurement is returned to the center-side device 8 (step P2).

The timer 6 of the subscriber unit 9 measures the time from when the power switch is turned on. If the timer has not timed out (step P3), the unstable state information sending circuit 5 sends the unstable state information. (Step P4).
The unstable state information from the unstable state information sending circuit 5 is superimposed on the delay value measuring cell from the delay amount measuring cell sending circuit 3. That is, the cell on which the unstable state information is superimposed is a cell that has been transmitted in an unstable state such as immediately after power-on of the subscriber-side device and has not been returned in a normal response time.

The center device 8 receives the returned cell by the delay amount measuring cell detection circuit 4 and the unstable state detection circuit 7 (FIG. 2, step S2).

When the unstable state detecting circuit 7 detects the unstable state information (step S3), the delay amount measuring cell detecting circuit 4 discards the returned cell (step S3).
4). Therefore, in the delay amount measuring cell detection circuit 4,
Only cells returned in the regular response time will be received.

The cell detection circuit 4 for measuring the amount of delay, based on the cell transmission time of the transmission circuit 1 for measuring the amount of delay, determines the subscriber unit 9
Is measured (step S5), and each time difference is recognized as a delay time of each subscriber side device 9.

Thereafter, the amount of delay is set in each subscriber unit so that the delay time of each subscriber unit becomes equal.

[0023]

As described above, according to the present invention, the subscriber unit is provided with a timer and an unstable state information sending circuit, and the unstable state information is superimposed on the return cell at the time of delay measurement, and the received signal is received. Since the center-side device can discard the cell, the center-side device has an effect that the delay measurement in the subscriber-side device steady state can be performed.

[Brief description of the drawings]

FIG. 1 is a diagram showing one embodiment of the present invention.

FIG. 2 is a flowchart showing an operation of the center-side device.

FIG. 3 is a flowchart showing the operation of the subscriber device.

FIG. 4 is a diagram showing a conventional propagation delay amount measuring method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Delay amount measurement instruction sending circuit 2 Delay amount measurement instruction detecting circuit 3 Delay amount measuring cell sending circuit 4 Delay amount measuring cell detecting circuit 5 Unstable state information sending circuit 6 Timer 7 Unstable state information detecting circuit 8 Center unit 9 Subscriber side device 10 Star coupler

Claims (3)

(57) [Claims] 1. A method for measuring a propagation delay amount by transmitting and receiving cells between a subscriber unit and a center unit in a PDS optical subscriber system, wherein the subscriber unit is turned on. A timer for measuring the time from, and an unstable state information sending circuit that sends the unstable state information superimposed on the delay amount measuring cell during the time until the timer times out, The center-side device is controlled by an unstable state information detecting circuit for detecting the unstable state information from the subscriber side device, and by discarding the delay amount measurement cell by the output of the unstable state information detecting circuit. And a propagation delay amount measuring circuit. 2. The propagation delay amount measuring method according to claim 1, wherein said timer starts when a power switch is turned on, and times out when the subscriber unit reaches a stable state. 3. The unstable state detecting circuit, when detecting an unstable state, causes the propagation delay amount measuring circuit to discard a cell transmitted from a subscriber side device. Propagation delay measurement method.