JPH10200975A - Synchronization method between subscriber units in star type optical subscriber system - Google Patents

Abstract

(57) [Summary] [PROBLEMS] In a star-type optical subscriber system, the operation timings of respective subscriber units are made to coincide with each other to synchronize them. SOLUTION: The intra-station device has a transmission delay time calculating section 19 between the intra-station device and each subscriber device, and notifies the subscriber device of the transmission delay time by a downlink signal from the intra-station device to each subscriber device. The subscriber unit extracts transmission delay time information in the downlink signal, and sets a timing obtained by advancing the transmission delay time with respect to a predetermined temporary operation timing to a true operation timing, so that each subscriber device The operation timing in the device can be matched.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a synchronization system between subscriber units of a star type optical subscriber system.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing a configuration of an intra-office device which is a part of a switching center of a conventional star type optical subscriber system, and FIG. 8 is a configuration of a subscriber device of a conventional star type optical subscriber system. FIG. 9 is a block diagram showing a configuration of a star type optical subscriber system, and FIG. 10 is a diagram showing signal states and operation timings between an intra-office device and a subscriber device.

[0003] Hereinafter, embodiments and operations of the related art will be described.

As shown in FIG. 7, the configuration of an intra-station device is an optical module 71 for transmitting and receiving an optical signal through an optical fiber from a subscriber side, and an optical / electrical converter for converting a received optical signal into an electric signal. 72, a frame decomposing unit 73 that decomposes the upstream frame converted into the electric signal, a clock extracting unit 74 that extracts the bit timing from the received signal, and establishes the frame synchronization based on the upstream frame converted into the electric signal. It comprises a frame synchronization unit 75, a buffer 76 used for speed matching with the network side 79, a frame assembly unit 77 for assembling a downstream frame, and an electrical / optical converter 78 for converting a downstream frame of an electric signal into an optical signal. .

[0005] Further, as shown in Fig. 8, the configuration of the subscriber unit includes an optical module 81 for transmitting and receiving an optical signal from a network side 79 through an optical fiber, and an optical / electrical converter for converting the received optical signal into an electric signal. Unit 82, a frame decomposing unit 83 that decomposes the downstream frame converted into the electric signal, a clock extracting unit 84 that extracts the bit timing from the received signal, and establishes the frame synchronization based on the downstream frame converted into the electric signal. A frame synchronizing unit 85, a buffer 86 used for speed matching with the terminal side 80, a frame assembling unit 87 for assembling a transmission frame to the terminal side, a frame decomposing unit 88 for decomposing a received frame from the terminal side, It comprises a frame assembling section 89 for assembling an upstream frame to the side 79, and an electric / optical conversion section 810 for converting an upstream frame of an electric signal into an optical signal.

Next, the in-station equipment shown in FIGS.
FIG. 9 shows the configuration of a star-type optical subscriber system composed of subscriber units. Here, the transmission distance is set to the subscriber device B <
It is assumed that the subscriber device A <the subscriber device C. Although not particularly limited, the operation of each subscriber device will be described here as transmission to the terminal.

[0007] Each subscriber unit transmits to the terminal after a predetermined time (hereinafter abbreviated as delay time in the subscriber unit) has elapsed from the beginning of the downstream frame. The delay time in each subscriber unit is the same for all subscriber units. As shown in FIG. 10, the downstream frame (a) reaches the order of the subscriber device B, the subscriber device A, and the subscriber device C.
Therefore, in the upstream frame (b), transmission to the terminal side is also performed in the order of the subscriber unit B, the subscriber unit A, and the subscriber unit C.

[0008]

As described above, in the above-mentioned conventional star type optical subscriber system, the transmission timing, that is, the operation timing is different in each subscriber unit. For example, when a PHS (Personal Handyphone System) is connected to a subscriber device, radio waves transmitted from a PHS base station are not synchronized. FIG. 11 shows a state where the radio waves are not synchronized between the subscriber unit A and the subscriber unit B. Although the subscriber device A uses only one line, the subscriber device B cannot use two lines, and thus has a problem that radio wave use efficiency is reduced.

An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to improve the use efficiency of radio waves by making the operation timings of the respective subscriber devices coincide.

[0010]

According to the present invention, in order to solve the above-mentioned problems and to achieve the object, an intra-office device has a means for calculating a transmission delay time between an intra-office device and each subscriber device. The time is notified to the subscriber unit by a downlink signal from the intra-station device to each subscriber unit, and the subscriber unit has means for extracting transmission delay time information in the downlink signal, and extracts the transmission delay time information. In this case, the actual operation timing is obtained by advancing the transmission delay time with respect to the predetermined temporary operation timing. As described above, it is possible to make the operation timings of the respective subscriber devices coincide with each other and to synchronize the respective subscriber devices.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION
The intra-office device has means for calculating a transmission delay time between the intra-office device and each subscriber device, and notifies the subscriber device of the transmission delay time by a downlink signal from the intra-station device to each subscriber device. The device has means for extracting transmission delay time information in the downlink signal, extracts the transmission delay time information, and sets the transmission delay time earlier than the predetermined temporary operation timing by the real operation time. The timing has the effect that the operation timings of the respective subscriber units can be matched to synchronize the respective subscriber units.

According to a second aspect of the present invention, there is provided an intra-office device for calculating a transmission delay time between the intra-office device and each of the subscriber devices, and further comprising a predetermined subscriber device based on the transmission delay time. Means for calculating a timing obtained by advancing the transmission delay time with respect to the provisional operation timing as a true operation timing, wherein the true operation timing is added by a downlink signal from the intra-station device to each subscriber device. By notifying the subscriber device, the operation timing in each subscriber device is matched, and the correction of the transmission delay time of each subscriber device is calculated in the intra-office device. This has the effect of reducing costs.

According to a third aspect of the present invention, in the intra-office device, the provisional operation timing is set as the head timing of a downstream frame in the subscriber device having the maximum transmission delay time. Has the effect of making the operation timings coincide with each other and setting a minimum time from the transmission timing of the downstream frame of the intra-station device to the operation timing of the subscriber device.

Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 to 6 and FIG. Although not particularly limited, a description will be given of a case where transmission to a terminal side is performed as an operation in each subscriber device. That is, an object of the present invention is to match transmission timings to terminals in each subscriber device.

(Embodiment 1) FIG. 1 is a block diagram showing a configuration of an intra-station device according to Embodiment 1 of the present invention.
As shown in FIG. 1, an optical module 11 for transmitting and receiving an optical signal through an optical fiber from a subscriber side 10, an optical / electrical conversion unit 12 for converting a received optical signal into an electric signal, Frame decomposer that decomposes upbound frames
13, a clock extracting unit 14 for extracting bit timing from a received signal, a frame synchronizing unit 15 for establishing frame synchronization based on an upstream frame converted into an electric signal, and a buffer 16 used for speed matching with the network side 100. A frame assembling unit 17 for assembling a downstream frame for notifying a subscriber device of a transmission delay time, which will be described later, and an electric / optical converter 18 for converting a downstream frame of an electric signal into an optical signal are provided in the conventional station shown in FIG. The configuration is almost the same as the device. Here, reference numeral 19 denotes a transmission delay time calculation unit for calculating a transmission delay time between the newly provided intra-station device and the subscriber, and is connected to the frame disassembly unit 13 and the frame assembly unit 17.

Hereinafter, one means of calculating the transmission delay time in the transmission delay time calculation section 19 will be described. The intra-station device transmits a downlink frame to each subscriber device, and each subscriber device sends an uplink frame back to the intra-station device a specific time after receiving the downlink frame from the intra-station device. The upstream frame sent from the subscriber is received, the transmission delay time calculation unit 19 detects the phase difference between the downstream frame and the upstream frame, and calculates the transmission delay time between the intra-station device and each subscriber device from the phase difference. I do.

FIG. 2 is a block diagram showing the configuration of the subscriber unit according to Embodiment 1 of the present invention. As shown in FIG. 2, an optical module 21 connected to an optical fiber on the network side 100 is provided.
An optical / electrical conversion unit 22 for converting a received optical signal into an electric signal, a frame decomposing unit 23 for decomposing a downstream frame converted into an electric signal, and a clock extracting unit 24 for extracting bit timing from the received signal. A frame synchronization unit 25 for establishing frame synchronization based on the downstream frame converted into an electric signal, and a buffer 2 used for speed matching with the terminal 110.
6, a frame assembly unit 27 for assembling a transmission frame to the terminal side, a frame disassembly unit 28 for disassembling a reception frame from the terminal side, a frame assembly unit 29 for assembling an upstream frame to the network side, and The electrical / optical converter 210 for converting a frame into an optical signal has substantially the same configuration as the conventional subscriber unit shown in FIG. Here, reference numeral 211 denotes a transmission delay time information extracting unit that extracts a transmission delay time from a newly provided downlink frame, and 212 generates a transmission timing signal to a terminal whose transmission delay time has been corrected based on the transmission delay time and a frame synchronization signal. This is the operation timing generator that performs the operation. In this operation timing generation unit 212, to indicate the transmission timing to the temporary terminal, indicating the period of the transmission timing from the beginning timing of the downlink frame to the temporary terminal,
A specific time (hereinafter, abbreviated as “temporary delay time in the subscriber device”) is stored in advance. The temporary delay time in the subscriber unit is the same value for all the subscriber units, and is longer than the sum of the processing time in the subscriber unit and the transmission delay time from the in-station unit to the subscriber unit. Set.

In the configuration of the star type optical subscriber system shown in FIG. 9, similarly to the above, the transmission distance is assumed to be subscriber device B <subscriber device A <subscriber device C, and the intra-office device shown in FIG. The operation will be described with reference to the signal states and operation timing diagrams between the terminal and the subscriber unit.

Downstream frame (a) from intra-station device (FIG. 1)
Because the transmission distances are different, the subscriber device B, the subscriber device A, and the subscriber device C arrive at the subscriber device in this order. The frame synchronization section 25 of the subscriber unit (FIG. 2) outputs the head timing of the downstream frame as a frame synchronization signal. In the transmission delay time information extracting unit 211 of the subscriber device,
The transmission delay time calculated by the transmission delay time calculation unit 19 of the intra-station device is extracted from the downstream frame. The operation timing generator 212 includes a head of the downlink frame output from the frame synchronizer 25, a transmission delay time output from the transmission delay time information extractor 211, and a temporarily stored temporary delay in the subscriber device. Based on the time, the following timing (Equation 1) is used to calculate and output the head timing D (FIG. 3) of the transmission frame to the terminal.

[0020]

## EQU1 ## The head of the downstream frame + the temporary delay time in the subscriber unit-the transmission delay time The frame assembling unit 29 in the terminal unit on the terminal side outputs the head of the transmission frame to the terminal output from the operation timing generation unit 212. At timing D, the transmission frame is transmitted. Accordingly, since the transmission delay time is corrected for the start timing of the transmission frame to the terminal of each subscriber device, the terminal of the subscriber device A, the subscriber device B, and the subscriber device C as shown in FIG. The timings of the transmission frames to are matched.

As described above, according to the first embodiment, a transmission delay time calculating section 19 for calculating a transmission delay time between an intra-office device and a subscriber, and adding the transmission delay time to a downstream frame in a downstream frame. A transmission delay time information extracting unit 211 for extracting transmission delay time information from a downstream frame, and a transmission delay time, a frame synchronization signal, and a pre-stored information in the subscriber device. By providing an operation timing generator 212 that generates a transmission timing signal to a terminal whose transmission delay time has been corrected based on the provisional delay time, the transmission timing to each terminal in each subscriber device is matched, that is, the synchronization is performed. Can take.

(Embodiment 2) Next, Embodiment 2 and its operation will be described with reference to FIGS.
FIG. 4 is a block diagram showing a configuration of an intra-station device according to Embodiment 2 of the present invention. The components from the optical module 11 to the transmission delay time calculator 19 shown in FIG. 4 are the same as those in the intra-station device of FIG. Therefore, reference numeral 20 denotes an operation timing calculation unit, and a temporary delay time in the subscriber device stored in advance,
Based on the transmission delay time calculated by the transmission delay time calculation unit 19, a true delay time in each subscriber device in the subscriber device is calculated. The true delay time in the subscriber device is the time from the start timing of the downlink frame to the transmission timing to the terminal side, and is expressed by the following (Equation 2).

[0023]

## EQU2 ## The provisional delay time in the subscriber unit minus the transmission delay time The calculated true delay time in the subscriber unit is reported to the subscriber unit in a downstream frame.

FIG. 5 is a block diagram showing a configuration of a subscriber unit according to Embodiment 2 of the present invention. 5 from the optical module 21 to the electrical / optical converter 210 shown in FIG.
Is the same as that of the subscriber device. Here, reference numeral 213 denotes an operation timing generation unit, which sends the terminal to the terminal by the following (Equation 3) based on the head of the reception frame output from the frame synchronization unit 15 (FIG. 4) and the operation timing in the downlink frame. , And outputs the start timing of the transmission frame.

[0025]

## EQU3 ## The head of the received frame + the true delay time in the subscriber unit The frame assembling unit 27 in the terminal side subscriber unit outputs the head timing D of the transmission frame to the terminal output by the operation timing generation unit 213 (see FIG. 6), the transmission frame is transmitted. Accordingly, since the transmission delay time is corrected for the start timing of the transmission frame to the terminal of each subscriber unit, the subscriber unit receives a signal like the signal state and operation timing between the intra-office unit and the subscriber unit in FIG. The timings of A, subscriber device B, and subscriber device C coincide.

As described above, according to the second embodiment, the first embodiment is different from the first embodiment in that the operation timing calculation unit 20 for calculating the operation timing of the subscriber unit is provided in the intra-office device. In the second embodiment, the calculation of the true delay time in the subscriber device is performed by each subscriber device. On the other hand, in the second embodiment, the calculation is performed by the intra-station device. Cost can be reduced.

(Embodiment 3) Next, the operation of Embodiment 3 will be described. In the second embodiment, the provisional delay time in the subscriber device is predetermined, but in the third embodiment, the maximum transmission delay time between the intra-office device and the subscriber device. Therefore, the operation timing calculation unit 20 shown in FIG.
Based on the transmission delay time calculated by the transmission delay time calculation unit 19 and the maximum value, a true delay time in the subscriber device is calculated by the following (Equation 4).

[0028]

## EQU4 ## Maximum transmission delay time-transmission delay time The subsequent processing is the same as in the second embodiment.

In the subscriber unit having the maximum transmission delay time, the head of the transmission frame to the terminal can be output immediately after the head of the downstream frame. Therefore, the start timing of the transmission frame of each subscriber unit to the terminal coincides with the timing of the subscriber unit A, the subscriber unit B, and the subscriber unit C, and the transmission to the terminal unit is performed with the minimum transmission delay time. It can be carried out.

As described above, according to the present embodiment, the operation timing in each subscriber unit is matched, and the time from the transmission of the downstream frame of the in-station unit to the operation in the subscriber unit is set to a minimum. can do.

[0031]

As described above, according to the present invention, since the operation timings of the respective subscriber units can be matched, for example, when connecting to a PHS (Personal Handy Phone System) subscriber unit, Radio waves transmitted from the base station of the PHS connected to the subscriber unit can also be synchronized, thereby preventing a reduction in radio wave use efficiency.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an intra-station device according to Embodiment 1 of the present invention.

FIG. 2 is a block diagram illustrating a configuration of a subscriber device according to Embodiment 1 of the present invention.

FIG. 3 is a diagram illustrating signal states and operation timings for explaining the operation of the first embodiment of the present invention.

FIG. 4 is a block diagram showing a configuration of an intra-station device according to Embodiment 2 of the present invention.

FIG. 5 is a block diagram showing a configuration of a subscriber device according to Embodiment 2 of the present invention.

FIG. 6 is a diagram illustrating signal states and operation timings for explaining the operation of the second embodiment of the present invention.

FIG. 7 is a block diagram showing a configuration of an intra-station device according to a conventional embodiment.

FIG. 8 is a block diagram illustrating a configuration of a subscriber device according to a conventional embodiment.

FIG. 9 is a block diagram showing a configuration of a star type optical subscriber system.

FIG. 10 is a diagram showing signal states and operation timings for explaining the operation in the conventional embodiment.

FIG. 11 is a diagram showing a radio signal state of a PHS (Personal Handyphone System).

[Explanation of symbols]

11, 21… Optical module, 12, 22… Optical / electrical converter,
13, 23, 28 ... frame decomposition unit, 14, 24 ... clock extraction unit, 15, 25 ... frame synchronization unit, 16, 26 ... buffer,
17, 27, 29: frame assembling unit, 18, 210: electric / optical conversion unit, 19: transmission delay time calculation unit, 20: operation timing calculation unit, 211: transmission delay time information extraction unit, 21
2, 213: operation timing generator.

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Claims (3)

[Claims] 1. An optical subscriber in which a switching center and a plurality of subscribers are connected in a star configuration by an optical fiber and an optical splitter, and a time division multiplex communication is performed between the switching center and the plurality of subscribers. In the system, when deciding the operation timing in each of the subscriber devices for synchronizing the operation in each of the subscriber devices, the intra-station device calculates a transmission delay time between the intra-station device and each of the subscriber devices. And notifies the subscriber unit of the transmission delay time by a downlink signal from the intra-station device to each of the subscriber devices, and the subscriber device extracts transmission delay time information in the downlink signal. Means for extracting the transmission delay time information, and setting a timing obtained by advancing the transmission delay time with respect to a predetermined temporary operation timing as a true operation timing. of Synchronization method between subscriber devices. 2. An optical subscriber in which a switching center and a plurality of subscribers are connected in a star configuration by an optical fiber and an optical splitter, and a time division multiplex communication is performed between the switching center and the plurality of subscribers. In the system, when deciding the operation timing in each of the subscriber devices for synchronizing the operation in each of the subscriber devices, the intra-station device calculates a transmission delay time between the intra-station device and each of the subscriber devices. Means for calculating, as a true operation timing, a timing obtained by advancing the transmission delay time with respect to a predetermined temporary operation timing in the subscriber device based on the transmission delay time, Wherein the operation timing is notified to the subscriber unit by a downlink signal from the intra-station unit to each of the subscriber units. 3. The star according to claim 2, wherein, in the intra-station device, the provisional operation timing in the subscriber device is a head timing of a downstream frame in the subscriber device having the maximum transmission delay time. Synchronization method between subscriber units of a mobile optical subscriber system.