JPH11136195A - Distance measurement method in optical burst communication and distance measurement system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the accuracy of a delay instruction value, not by processing a clock function and a distance measurement function separately, but by using a phase difference between a reference clock from the clock function and a clock actually sampled as a fraction part to improve the accuracy of distance measurement. SOLUTION: For distance measurement in an optical burst communication where communication is conducted through an optical fiber between a plurality of subscriber's equipment and station equipment via a photocoupler, the processing result of a clock extracting function of burst data 16 is processed as a correction signal for distance measurement. In this case, a distance measurement device 25 is employed, which uses a phase difference between a reference clock 27 and a clock actually sampled as a fraction part, wherein the fraction part is processed for a correction signal of distance measurement, and the fraction part is used for a delay instruction value 26 between the subscriber's equipment and the station system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a distance measuring method and a distance measuring apparatus in optical burst communication in which a plurality of subscriber units and a central office communicate with each other via optical fibers via optical couplers.

[0002]

2. Description of the Related Art In an optical burst communication apparatus for communicating a plurality of subscriber units and office equipment via an optical fiber via an optical coupler, when the transmission distance between the subscriber re-installation and the office equipment is different, The data transmission time from each subscriber device to the office equipment has an arrival time difference according to the transmission distance.

If the arrival time difference is large, the data is packed and there is no delay, so that the transmission band cannot be used sufficiently. Therefore, in order to reduce the arrival time difference, a delay instruction value which is a data transmission time for canceling the arrival time is set for each subscriber device. By setting this delay instruction value, the transmission band can be effectively used by reducing the time difference between the data transmitted from each subscriber device and the arrival at the station device. The setting of the delay instruction value uses the measurement result of the distance measuring device mounted on the station apparatus.

[0004] This technology uses TDMA (Time Division Multiple Access).
As a method, it is widely used in satellite communication as described in JP-A-1-181338.

(Background Art of the Invention) FIG. 6 is a block diagram showing a distance measuring technique in optical burst communication. This distance measuring technique is mounted on a station apparatus, and includes a polyphase clock generator 51, a clock phase detector 53, a polyphase clock selector 55, a writer 57, an elastic store 59,
Readout device 61, cell phase detector 63, distance measuring device 6
5. The configuration including the averaging unit 68.

A clock phase detector 53 and a multi-phase clock selector 55 select a clock phase of a burst data signal 56 from a plurality (eight in the figure) of the multi-phase clock signals 52 by the multi-phase clock generator 51. Is selected and written into the elastic store 59 by the writer 57.

[0007] The read unit 61 uses the reference clock 69 as a read clock to read data 60 read from the elastic store 59 as output data 62. The cell phase detector 63 detects the head of the cell from the output data 62 using the reference clock 69 as a clock source,
It is output as a cell phase signal 64.

A distance measuring device 65 measures a distance from the cell phase signal 64 using a reference clock 69 as a clock source.
The distance measurement value signal 68 is output to the averager 67. The averager 67 takes an average value of the distance measurement value signal 66 based on a plurality of inputs, and outputs the average value as a delay instruction value signal 68.

By the way, in the distance measuring technique in the optical burst communication, the clock extracting function and the distance measuring function are separately processed. In the clock extracting function, the reference clock extracted from the burst data is extracted and the distance measuring function is performed. Calculated the distance measurement value with the precision of the reference clock and the significant figure of the delay indication value. The distance measurement unit is
In order to improve the accuracy of the delay instruction value, a method of measuring the distance several times and averaging the distance measurement values to determine the delay instruction value is used.

[0010]

The problem is to reduce the usable bandwidth of the transmission line because the accuracy of distance measurement cannot be improved. The reason is that it is necessary to increase the number of distance measurements in order to increase the accuracy of the delay indication value, or to increase the time between burst signals, and to increase the bandwidth that can be used originally for data communication. It is to decrease.

The present invention has been made in view of the above points, and does not treat the clock function and the distance measuring function separately, but uses the clock function as a reference clock to improve the accuracy of distance measurement. It is an object of the present invention to provide a technique capable of improving the accuracy of a delay indication value by using a phase difference of a clock being sampled as a decimal part.

[0012]

According to the present invention, there is provided a distance measuring method in optical burst communication in which a plurality of subscriber units and a central office unit communicate with each other through optical fibers via optical couplers.
In this method, the processing result of the clock extraction function of the burst data is processed as a correction amount of the distance measurement. In this case, it is also possible to use a distance measuring device that uses the phase difference between the reference clock and the clock actually sampled as a decimal part, and process the decimal part as a correction amount for distance measurement. Also,
The decimal part can be used as a delay indication value between the subscriber device and the office equipment. Further, in the present invention, in a distance measurement device between each subscriber device and a station device in optical burst communication in which a plurality of subscriber devices and a station device are communicated via optical fibers via optical couplers, a clock extraction function is provided. The apparatus is provided with means for processing the processing result as a correction amount for distance measurement. In that case, a distance measuring device that uses the phase difference between the reference clock and the clock actually sampled as a decimal part, and the distance measuring device has a function of processing the decimal part as a correction amount of the distance measurement. Can also. A multi-phase clock generator for sampling burst data, a clock phase detector for sequentially selecting a clock phase closest to the phase of the burst data from the multi-phase clock signal and outputting a clock selection signal, A polyphase clock selector for selecting and outputting a sampling clock indicating a signal most suitable for sampling according to the clock selection signal from the polyphase clock signals, and a writer for writing burst data to storage means based on the sampling clock. A reader for reading one of the multiphase clock signals as a reference clock and reading burst data of a storage means as output data, and a cell phase for detecting the head of a cell from the output data based on the reference clock and outputting it as a cell phase signal A detector, a cell phase signal, and a clock selection signal are input. And a releasing instrument, the distance measuring instrument can also be configured to include a function of outputting a delayed instruction value signal as an integer part and a fractional part of the distance measurement based on the cell phase signal to the reference clock. Further, the distance measuring device can also use the phase difference in the clock of the reference clock from the clock selection signal as a decimal part of the distance measurement. further,
A configuration including means for processing burst data in a multi-phase manner may also be employed.

In the present invention, the clock function and the distance measurement function are not separately handled, and the phase difference between the reference clock, which is the clock function, and the clock being actually sampled is used as the decimal part in order to increase the accuracy of the distance measurement. By doing so, it is not necessary to perform a plurality of distance measurements for improving the accuracy of the delay indication value. Alternatively, when distance measurement is performed a plurality of times, a delay instruction value with higher accuracy can be output.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a block diagram showing an embodiment of a transmission line system to which the present invention is applied, FIG. 2 is a timing chart thereof, and FIG. 3 is a diagram showing a distance measuring technique in optical burst communication according to Embodiment 1 of the present invention. 6 is a similar block diagram, and FIG. 4 is a timing chart thereof.

(Embodiment 1) In the transmission line system shown in FIG. 1, the subscriber unit 1 (70) and the subscriber unit 2 (7)
1), subscriber unit 3 (72), subscriber unit n (73)
The station apparatus 81 performs a burst communication via the transmission line 80.

The transmission line 80 has a configuration in which optical fibers are connected in a star shape via a coupler 79. The output burst data 74 of the subscriber unit 1, the output burst data 75 of the subscriber unit 2, and the output burst data of the subscriber unit 3.
The output data 77 of the subscriber unit n is output from the subscriber unit 1 in accordance with the path difference when passing through the transmission line 80, as shown by the arrow and the corresponding broken line in FIG. 90, transmission line delay 91 of the subscriber unit 2, transmission line delay 92 of the subscriber unit 3, transmission line delay 9 of the subscriber unit n
The station apparatus 81 is output as the station entering coverst signal 78 through the station 3.
To reach.

A distance measuring technique (apparatus) according to the first embodiment
Is mounted on the station building 81, and the multi-phase clock generator 1
1, clock phase detector 13, polyphase clock selector 1
5, a writing unit 17, an elastic store 19, a reading unit 21, a cell phase detector 23, and a distance measuring unit 25. (Explanation of Operation of First Embodiment) FIG. 4 shows an operation timing chart of the operation. The multi-phase clock generator 11 generates two or more multi-phase clock signals 12 whose phases are shifted evenly in order to sample the burst data signal 16. Here, eight cases are shown. The clock phase detector 13 determines the clock phase whose rising edge is closest to the changing point of the burst data 16 as the multiphase clock signal 1.
2 are sequentially selected and a selection signal 14 is output.

The multiphase clock selector 15 selects and outputs a sampling clock 28 as a value indicating a signal most suitable for sampling according to the selection signal 14 from the multiphase clock signal 12. The writer 17 outputs the write data 18 so as to write the burst data 16 at the falling edge of the sampling clock 28,
Write to elastic store 19.

The readout unit 21 comprises a cell phase detector 23,
Using the distance measuring device 25 and the reference clock 27 for processing the output data as the read clock, the data 20 read from the elastic store 19 as the burst data 16 is read as the output data 22.

The cell phase detector 23 detects the head of the cell from the output data 22 using the reference clock 27 as a clock source, and outputs it as a cell phase signal 24.

The distance measuring device 25 uses the reference clock 27 as a clock source from the cell phase signal 24 and uses it as an integer part of distance measurement. The distance measuring device 25 outputs the phase difference within the clock of the reference clock 27 from the clock selection signal 14 as the fractional part of the distance measurement, and outputs it as the delay indication value signal 26 and the nearest integer value.

FIG. 4 shows the case where the integer part is X + 1 and the part where the decimal part is 3 and 5 as indicated by the broken lines in the figure. In this case, if the delay instruction value signal is required to be a positive number, the former is X + 1, and the latter is X +
As 2, the delay instruction value signal 26 is output.

(Embodiment 2) FIG. 5 shows Embodiment 2 of the present invention. In the case of FIG. 5, the first embodiment is a method of multi-phase clock, whereas the first embodiment is a method of multi-phase data. In this case, the data selection signal 36 is used for the precision of the minority part.

(Explanation of Operation of Second Embodiment) In order to sample the burst data signal 36, the multi-phase clock generator 31 outputs two or more multi-phase clock signals (group) 32 whose phases are shifted evenly. Occur. Here, eight cases are shown.

The clock phase detector 33 sequentially selects a clock phase whose rising edge is closest to the changing point of the burst data 36 from the multiphase clock signal 32 and outputs a selection signal 48.

The writer group 37 includes burst data 36
Is written at the rising edge of each of the multiphase clock signal groups 32, and is written to the elastic store group 39.

The read unit group 41 receives the multi-phase clock signal 3
The reference clock 47, which is one of the two, is output to the data selector 34 as a read clock. The data selector 34 outputs one of the signals from the reader group 41 as an output signal 42 according to the selection signal 48.

The cell phase detector group 43 outputs the output data 42
, The top of the cell is detected using the reference clock 47 as a clock source and output as the cell phase signal 44.

The distance measuring device 45 uses the reference clock 47 from the cell phase signal 44 as a clock source and uses it as an integer part of the distance measurement. Further, the distance measuring device 45 sets the phase difference within the clock of the reference clock 47 from the clock selection signal 48 as the fractional part of the distance measurement, and outputs it as the delay instruction value signal 46 and the nearest integer value.

[0030]

The first effect is to reduce the number of distance measurements by increasing the accuracy of the delay indication value, thereby increasing the bandwidth that can be used for originally transmitting data.

The second effect is that by increasing the accuracy of the delay instruction value, the time between burst signals is not required to be large, and the band that can be used for data communication is reduced.

The third effect is that, by increasing the accuracy of the delay indication value, the time between the burst signal and the burst signal is not changed, the preamble bit for extracting the burst transmission clock, and the cell phase are detected. By increasing the number of delimiter bits to be used, communication that is resistant to transmission errors can be performed.

[Easy sharp drawing]

FIG. 1 is a block diagram of a transmission path system to which the present invention is applied.

FIG. 2 is a timing chart of a transmission path system to which the present invention is applied.

FIG. 3 is a block diagram of a distance measuring device according to Embodiment 1 of the present invention.

FIG. 4 is a timing chart of the distance measuring device according to the first embodiment of the present invention.

FIG. 5 is a block diagram of a distance measuring device according to Embodiment 2 of the present invention.

FIG. 6 is a block diagram of a conventional distance measuring device.

[Explanation of symbols]

 Reference Signs List 11 polyphase clock generator 12 polyphase clock signal (group) 13 clock phase detector 14 clock selection signal 15 polyphase clock selector 16 burst data input 17 writer 18 write data signal 19 elastic store (storage means) 20 read Data 21 Readout device 22 Output data 23 Cell phase detector 24 Cell phase signal 25 Distance measuring device 26 Delay instruction value signal 27 Reference clock 28 Sampling clock 31 Multiphase clock generator 32 Multiphase clock signal group 33 Clock phase detection 34 Data selection Device 35 Output data signal group 36 Burst data input 37 Writer group 38 Write data signal group 39 Elastic store group 40 Read data signal group 41 Reader group 42 Output data signal 43 Cell phase detector 4 Cell phase signal 45 Distance measuring device 46 Delay instruction value signal 47 Reference clock 48 Selection signal 51 Multiphase clock generator 52 Multiphase clock signal (group) 53 Clock phase detector 54 Multiphase clock selector 55 Output data signal (group) 56 Burst data input 57 Writer 58 Write data signal 59 Elastic store 60 Read data signal 61 Reader 62 Output data signal 63 Cell phase detector 64 Cell phase signal 65 Distance measurement device 66 Distance measurement value signal 67 Averager 70 Subscription Subscriber device 1 71 Subscriber device 2 72 Subscriber device 3 73 Subscriber device n 74 Outgoing broadcast data of subscriber device 1 75 Outgoing broadcast data of subscriber device 2 76 Outgoing broadcast data of subscriber device 3 77 Subscription Outcast data of the user device n 78 Entering the office building device Burst data 79 fogged 80 transmission path 81 the station device 90 subscriber device 1 of the delay instruction value 91 subscriber device 2 of the delay instruction value 92 subscriber device 3 of the delay instruction value 93 delayed indication of the subscriber apparatus n

Claims (8)

[Claims] 1. A method for measuring a distance between a subscriber device and a station device in optical burst communication in which a plurality of subscriber devices and a station device communicate with each other through an optical fiber via an optical coupler,
A distance measurement method in optical burst communication, wherein a processing result of a clock extraction function of burst data is processed as a correction amount for distance measurement. 2. An optical burst, wherein a distance measuring device using a phase difference between a reference clock and a clock actually sampled as a decimal part is used, and the decimal part is processed as a correction amount for distance measurement. Distance measurement method in communication. 3. The distance measuring method in optical burst communication according to claim 2, wherein the decimal part is used as a delay indication value between the subscriber unit and the central office. 4. A distance measuring device between each subscriber device and a station device in optical burst communication in which a plurality of subscriber devices and a station device communicate via an optical fiber via an optical coupler, wherein a clock extracting function is provided. A distance measuring device for optical burst communication, comprising: means for processing the processing result of (1) as a correction amount for distance measurement. 5. A distance measuring device using a phase difference between a reference clock and a clock actually sampled as a decimal part, the distance measuring device processing the decimal part as a correction amount of the distance measurement. Characterized by having
Distance measuring device for optical burst communication. 6. A multi-phase clock generator for sampling burst data, and a clock phase detector for sequentially selecting a clock phase closest to the phase of the burst data from the multi-phase clock signal and outputting a clock selection signal A multi-phase clock selector for selecting and outputting a sampling clock indicating a signal most suitable for sampling according to the clock selection signal from the multi-phase clock signal, and the burst data based on the sampling clock. A writer for writing to storage means, a reader for reading one of the polyphase clock signals as a reference clock and reading burst data of the storage means as output data, and a head of a cell from the output data based on the reference clock. A cell phase detector for detecting and outputting as a cell phase signal; And a distance measuring device to which the clock selection signal is input.The distance measuring device converts the delay indication value signal as an integer part and a decimal part of the distance measurement from the cell phase signal based on the reference clock. The distance measuring device in optical burst communication according to claim 4, further comprising a function of outputting. 7. The distance measuring device in optical burst communication according to claim 6, wherein the distance measuring device uses a phase difference in the clock of the reference clock from the clock selection signal as a decimal part of the distance measurement. . 8. The distance measuring apparatus in optical burst communication according to claim 4, further comprising means for processing the burst data in a multi-phase manner.