KR101115251B1 - Time Division Multiple Passive Optical Network and its compensation method of routes difference and the recording media storing the program performing the said method - Google Patents

Abstract

The present invention relates to a time division multiple passive optical communication network, a path difference compensation method thereof, and a recording medium storing a program capable of implementing the same.

A time division multiple passive optical network according to an example of the present invention, a method for compensating path difference thereof, and a recording medium storing a program capable of realizing the same, measure a plurality of path distances disposed between a central office side device (COT) and a remote device (RT). By calculating the distance difference value for each path for normalizing the distance of each of the plurality of paths so as to correspond to the distance of the longest path, converting the distance difference value for each path into a time delay value, and then controlling the transmission timing of the uplink signal. Up-date the equalization delay information to be updated, and transmit the updated equalization delay information to the optical subscriber end (ONT) by reflecting the updated equalization delay information in the gate control information, and then the optical subscriber end (ONT) is upwardly updated according to the gate control information. Delay the transmission timing of the signal.

Optical Termination Device (OLT), Office History Device (COT), Remote Device (RT), Distance Correction Unit

Description

Time division multiple passive optical network and its compensation method of routes difference and the recording media storing the program performing the said method}

The present invention relates to a time division multiple passive optical network, a method for compensating path difference thereof, and a recording medium storing a program capable of implementing the same. More particularly, the present invention provides a method in which the lengths of each of the plurality of paths are virtually and logically normalized. The present invention relates to a time division multiple passive optical communication network that does not need to perform MAC ranging even when a path is changed due to protection switching, a path difference compensation method thereof, and a recording medium storing a program capable of implementing the same.

With the recent rapid increase in Internet traffic and the convergence of broadcasting and telecommunication services, the speed of subscriber networks has been increasing rapidly. Among these technologies, passive optical network (PON) technology is introduced due to the advantages of not only providing high bandwidth to subscribers but also significantly reducing the operating cost of the network since the OSP (outside plant) is composed of only passive components. This is spreading.

FTTH (Fiber to the Home) refers to a technology that can provide high quality-based broadband communication services by installing optical communication lines to subscribers' homes. In the implementation of an optical communication network for implementing FTTH, a passive optical network (PON) using a passive optical element is generally employed. Representative methods of a passive optical communication network include a time division multiple access (TDMA) method and a wavelength division multiple access (WDMA) method. Until now, the TDM-PON method has been mainly used, and the evolution to the WDM PON is gradually being made.

Figure 1 shows a schematic diagram showing the configuration of a conventional general TDM-PON.

TDM-PON is a structure in which subscribers share optical fiber with optical line terminal (OLT) of a telephone company by using time division technique. Currently, BPON and G-PON standardized by ITU-T, and E-PON standardized by IEEE It is used.

TDM-PON basically includes an optical line terminator (OLT), a remote node (RN), and an optical network terminator (ONT). The RN distributes the optical signal transmitted from the optical line terminator (OLT) into several optical signals and delivers them to the optical subscriber terminal (ONT), or combines the optical signals transmitted from the optical subscriber terminal (ONT) Do this.

In the TDM PON, downstream data is composed of continuous cells in the form of broadcasting and is provided to all optical line terminators (OLTs). The upstream data is a time division multiplexing scheme in which the ONT occupies a certain time slot in burst mode.

Looking at the current transmission method of the general TDM-PON, one optical transceiver is installed in the optical line terminal (OLT) of the telephone station from the perspective of the downlink signal to broadcast traffic to each subscriber, A remote node (RN) uses a 1xN optical splitter that simply splits optical power to distribute the downlink optical signal transmitted from the OLT to N subscriber lines. In Receiving a down signal from the optical termination device (OLT) and selectively transmits only the frame assigned to the subscriber to the subscriber.

In the transmission of the uplink signal, the ONT receives a dedicated time slot from the optical termination device (OLT) in advance through a MAC (Media Access Control) ranging process. In this case, the uplink data is transmitted only when the time slot allocated to it arrives, and the optical transmitter is completely turned off when the slot is not in its own slot. The uplink signal from each subscriber is combined in the optical splitter of the remote node to be connected to the optical termination device (OLT). Is sent to. In general, fixed wavelength light sources of 1480 nm to 1500 nm are used for OLT, and fixed wavelength light sources of 1260 nm to 1360 nm are used for ONT / ONU of subscriber side, but the possibility of changing the up and down wavelengths in the next generation TDM-PON and downward Increasing bandwidth by distributing signals to optical transceivers of various wavelengths has been discussed in the standardization organization.

As a result, the optical subscriber stations (ONTs) at different distances may overlap at the remote node (RN) when simultaneously transmitting cells upwards, so that the optical termination device (OLT) cannot detect an accurate bit stream or lose a cell. There is a problem that occurs.

Here, the relay device includes a station-side device (COT) for photoelectric conversion, and a remote device (RT) installed at a remote site and multiplexing a path, and between the station-side device (COT) and the remote device (RT). A plurality of light paths are arranged. Among them, the COT is installed at a location close to the TDM PON optical termination device OLT to perform optical multiplexing and photoelectric conversion. On the other hand, a remote device (RT), which is a remote device, is installed at a long distance for transmission over a long distance (usually 20 km or more) and is optically connected to a TDM PON RN to perform optical multiplexing and photoelectric conversion.

The long-distance transmission of the repeater usually means a distance of 20km or more, and the development of a device for transmitting a distance of about 20km to 40km is actively progressed, and some of them aim for a distance of 100km. On the other hand, TDM PON MAC ranging to determine the distance information to the optical subscriber end (ONT) can be performed if it can determine the remote device (RT) distance of the repeater. On the other hand, since all services are interrupted in the process of performing Mac ranging, it is advantageous to minimize the Mac ranging itself if possible.

Long-distance transmission through the relay device enables the construction of a FTTH network for remote sites, and the optical cable reduction effect due to optical multiplexing, but it is very disadvantageous to recover in the event of a failure in the optical path section of 20 km to 40 km or more than 40 km. In other words, it takes a long time for the operator to move directly to the point of failure, but it is also difficult to identify the long point of failure. Therefore, a method capable of quickly recovering in an unexpected situation such as cutting an optical cable is essential. As a result, it introduces a path protection function to cope with an abrupt failure, and puts multiple bypass paths in addition to the working path so that it can be quickly operated in the event of a failure. In this case, the path for the protection switching is the optical path section between the station side device (COT) and the remote device (RT).

On the other hand, the bypass route introduced for the protection switchover adopts a route completely different from the operation route, which means that the distance of each route is different. This causes a serious problem, which means that the range of the distance between the station-side device (COT) and the remote device (RT) means that the ranging must be restarted each time the path is changed. There is a problem that the path is switched and stopped until the ranging is driven and completed.

As a result, when changing the path by protection switching, the conventional method is to immediately switch over to the bypass path after confirming the failure of the operation path, and perform normal recovery by performing TDM PON MAC ranging again. The problem with this method is that first, Mac ranging must be re-run every time a change is made to the bypass path, and second, recovery is delayed, resulting in a long service interruption time and thus lowering operational performance.

The present invention compensates the distance difference to remove the effect of the TDM PON MAC ranging by the distance difference between the operating path and the bypass path when using the bypass path of any one of the plurality of bypass paths for protection switching of the optical path section. An object of the present invention is to provide a time division multiple passive optical communication network, a path difference compensation method thereof, and a recording medium storing a program capable of implementing the same.

Other objects and advantages of the present invention can be understood by the following description, and will be more clearly understood by the embodiments of the present invention. Also, it will be readily appreciated that the objects and advantages of the present invention may be realized by the means and combinations thereof indicated in the claims.

The path difference compensation method of a time division multiple passive optical communication network according to an embodiment of the present invention measures a plurality of path distances disposed between the station side device (COT) and the remote device (RT) so as to correspond to the distance of the longest path. Calculating a distance difference value for each path for calculating a distance difference value for each path for normalizing each distance; An equalization delay information updating step of converting distance difference values for respective paths into time delay values and then updating equalization delay information for controlling transmission timing of an uplink signal; And transmitting the equalization delay information to reflect the updated equalization delay information to the gate control information for controlling the optical transmitter included in the optical subscriber end (ONT) and transmitting the updated equalization delay information to the optical subscriber end (ONT).

Here, the step of calculating the distance difference value for each path may include: (a) measuring a distance for each path of each of a plurality of paths between the central station side device (COT) and the remote device (RT); (b) selecting the distance of the longest path of each measured path; And (c) calculating a distance difference value for each path for normalizing each path based on the longest path by comparing the distances of the selected longest paths with the respective path distances.

In addition, the distance for each path in step (a) can be obtained by measuring the round trip time of the distance measurement signal for each of the plurality of paths from the station side device (COT) to the remote device (RT).

In addition, the equation for measuring the distance for each path in step (a) can be expressed as the following equation.

[Equation]

Here, RTT refers to Round Trip Time, which is a time for the ranging signal to and from the station side device (COT) and the remote device (RT), Ve refers to the transmission speed of the ranging signal in the optical path.

In addition, the distance difference value for each path may be stored in a distance information database included in a time division multiple passive optical network (TDM PON) device.

In addition, the equalization delay information updating step may convert the distance difference value for each path into a time delay value according to the following equation.

[Equation]

Here, Td _i = time delay value, Delay _i is the distance difference value for each path, Ve is the transmission speed of the ranging signal in the optical path.

The equalization delay information updating step may update the equalization delay information according to the following equation.

[Equation]

Here, Ted _New denotes updated equalization delay information, Ted _Old denotes existing equalization delay information before being updated, and Td _i denotes a time delay value.

In addition, the path difference compensation method of the time division multiple passive optical network may further include, after the equalization delay information transmission step, the optical subscriber end (ONT) to control the transmission timing of the uplink signal according to the gate control information.

Here, the updated equalization delay information may calculate a start time of the gate control information that controls the transmission timing of the uplink signal.

In addition, the path difference compensation method of a time division multiple passive optical communication network is a new method when a path correction request due to protection switching is performed in a state in which a new path is added between the station side device (COT) and the remote device (RT) in addition to a plurality of paths. A distance difference value for each path including a path may be calculated, and first MAC ranging may be performed using the updated equalization delay information.

In addition, the computer-readable recording medium according to an example of the present invention includes a recording medium on which a program for implementing the above-described method is recorded.

In addition, the time-division multiple passive optical communication network according to an example of the present invention measures the plurality of path distances disposed between the station side device (COT) and the remote device (RT), the distance of each of the plurality of paths to correspond to the distance of the longest path A distance correction unit for calculating a distance difference value for each path for normalizing the signal and transmitting the calculated distance difference value to the optical termination device (OLT); After receiving the distance difference value for each path from the distance corrector and converting it to a time delay value, the equalization delay information for controlling the transmission timing of the uplink signal is updated (up-date) and included in the optical subscriber end (ONT). And an optical termination device (OLT) for transmitting to the optical subscriber end (ONT) to reflect the gate control information for controlling the optical transmitter.

Here, the distance correction unit includes a distance measuring unit for measuring the distance for each path for each of the plurality of paths between the station side device (COT) and the remote device (RT); A path distance analyzer for selecting a distance of the longest path among the measured paths; And a distance difference value calculator configured to compare distances of the selected longest path and respective path distances and calculate a distance difference value for each path for normalizing each path based on the longest path.

Here, the distance measuring unit may obtain a distance for each path by measuring a round trip time of the distance measurement signal for each of a plurality of paths from the station side device COT to the remote device RT.

The distance corrector may further include a distance information database for storing a distance difference value for each path.

In addition, the optical subscriber stage (ONT) is to control the turn on (Turn On) and turn off (Turn Off) of the optical transmitter included in the optical subscriber stage (ONT) in order to control the transmission timing of the uplink signal according to the gate control information Can be.

In addition, the optical termination device (OLT) includes a new path when a path correction request due to protection switching is performed in a state where a new path is added between the station side device (COT) and the remote device (RT) in addition to a plurality of paths. The distance difference value for each path may be calculated and the first MAC ranging may be performed using the updated equalization delay information.

According to the present invention, a time division multiple passive optical network, a method for compensating path difference thereof, and a recording medium storing a program capable of implementing the same are based on a maximum path distance based on a plurality of path distances between a central office device (COT) and a remote device (RT). By calculating the distance difference value for each path to virtually have the same length by normalizing to be the same, and by the optical subscriber end (ONT) delays the upward signal by the distance difference value for each path, a plurality of bypasses for protection switching of the optical path section When using the bypass path of any one of the paths, the TDM PON MAC ranging due to the difference between the operating path and the bypass path can be minimized.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

First, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals are assigned to the same components as much as possible, even if shown on different drawings. In the following description of the present invention, a detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear. In addition, the following will describe a preferred embodiment of the present invention, but the technical idea of the present invention is not limited thereto and may be variously modified and modified by those skilled in the art.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

2 is a view for explaining an example of a time division multiple passive optical communication network according to the present invention.

As shown, the time division passive optical communication network according to the present invention may include a distance corrector 100, an optical termination device (OLT, 200), and an optical subscriber end (ONT, 300).

The distance corrector 100 measures a plurality of path distances disposed between the country-side device COT and the remote device RT to normalize the distances of the plurality of paths so as to correspond to the distances of the longest paths. To calculate the distance difference value for each path to transmit to the optical termination device (OLT, 300).

The optical terminator 200 receives the distance difference value for each path from the distance corrector 100, converts the distance difference value into a time delay value, and then updates equalization delay information for controlling timing of transmission of an uplink signal. ) To transmit to the optical subscriber end (ONT) (300).

Such an optical termination device (OLT) 200 includes a PON OAM function unit (not shown) in charge of OAM (Operation, Administration, and Maintenance) and a PON MAC processing unit (not shown) for transmitting and receiving optical signals.

Here, the OAM receives the distance difference value for each path from the distance corrector 100 and updates the equalization delay information.

The PON MAC processing unit (not shown) reflects the updated equalization delay information to the gate control information for controlling the optical transmitter included in the optical subscriber end (ONT) to transmit to the optical subscriber end (ONT) (300). The gate control information includes a start time and length information. When the updated equalization delay information is reflected in the gate control information, the start time of the gate control information is calculated. do. In this case, the updated equalization delay information delays the start time of the gate control information.

The gate control information reflecting the updated equalization delay information is transmitted to the optical subscription cluster (ONT) 300.

As a result, when the gate control information reflecting the updated equalization delay information is transmitted to the optical subscriber end (ONT) 300, the optical subscriber end (ONT) 300 controls the optical transmitter according to the gate control information to control the uplink signal. The transmission timing is to delay the transmission timing of the uplink signal according to the distance difference value for each path.

Next, the optical subscriber end (ONT, 300) serves to control the transmission timing of the uplink signal according to the updated equalization delay information received from the optical termination device (OLT, 200).

More specifically, when the ONT 300 receives the gate control information reflecting the updated equalization delay information, the ONT 300 is included in the ONT 300 according to the start time of the gate control information. By controlling the turn on and turn off of the optical transmitter, the transmission timing of the uplink signal can be controlled.

Therefore, when the equalization delay information is updated to delay the start time of the gate control information, the ONT 300 causes the uplink signal of the optical transmitter according to the start time of the gate control information. It is controlled to delay the transmission timing of. In this way, distance compensation based on a distance difference value for each path may be performed on the uplink signal.

As such, distance compensation for delaying an uplink signal by a distance difference value for each path is performed even if the uplink signal is transmitted through a bypass path having a different length in the existing operation path due to protection switching. As the subscriber end (ONT) 300 delays and transmits the uplink signal, the operating path and the bypass path are virtually at the same distance from each other.

Therefore, even if the length is changed to a different path due to the protection switching, it is possible to prevent the collision between the upstream signals due to the path change without performing separate MAC ranging due to the change of the path length.

As described above, in the time division multiple passive optical communication network according to the present invention, the distance correction unit 100 calculates a distance difference value for each path, and the optical termination device (OLT) 200 provides equalization delay information according to the distance difference value for each path. By updating and terminating the uplink signal according to the updated equalization delay information, the optical termination device (ONT) 300 performs the distance compensation, thereby preventing the collision between the uplink signals even when the path distance is changed. There is no need to do the gong separately, so the service can be maintained continuously.

In addition, even when a new path is added between the station side device (COT) and the remote device (RT), the MAC ranging is performed only once for the first time of protection transfer, and the separate MAC ranging is performed separately for the subsequent protection transfer. There is no need to do this, and there is an effect that can provide a higher quality service.

In more detail, when there is an operation path and a plurality of bypass paths between the station-side device and the remote device (RT) as shown in FIG. 2, when a failure occurs in the operation path, the operation path is one of the plurality of bypass paths. Protective switching takes place.

In this case, according to the related art, as described above, the MAC ranging must be performed to determine the distance to the optical subscriber terminal (ONT) through the selected bypass path. As a result, every time the protection switchover occurs due to a failure, the MAC ranging can only be driven, and service disconnection is inevitable.

However, when the distance compensation is performed according to the distance difference value for each path so that the distance for each of the plurality of paths corresponds to the distance of the longest path, as in the present invention, both the operation path and the detour path are virtually the same distance. It can be configured to have.

In this way, the distances of all paths are virtually the same, and the distance to the optical subscriber end (ONT) becomes the same even if the path to be operated by protection switching is changed to any bypass path, so the path distance to the optical subscriber end (ONT) There is no need to perform a separate Mac ranging to figure out.

Therefore, in the long run, the time for performing MAC ranging is relatively reduced, thereby minimizing the time for service interruption. In addition, since the distance correction unit 100 can be used while minimizing the change of the conventional time division multiple passive optical communication network (TDM PON), there is an effect that can maintain the stability of the device operation well.

And, if a new route is added between the country-side device (COT) and the remote device (RT), the distance correction unit 100 targets only the newly added detour route or including the newly added detour route. The distance for each path may be calculated for a target, and the distance difference value for each path may be newly calculated by selecting the longest path.

By doing so, it is possible to minimize the effects of the newly added bypass route while maintaining the service continuously through the operation route.

Hereinafter, a detailed configuration and function of the distance corrector 100 will be described in more detail.

3 is a view for explaining an example of the distance correction unit and the optical termination device (OLT) in FIG.

As illustrated, the distance corrector 100 includes a distance measurer 110, a path distance analyzer 120, and a distance difference calculator 130.

The distance measuring unit 110 measures a distance with respect to each of the plurality of paths between the office-side apparatus COT and the remote apparatus RT.

Here, the distance measuring method can be obtained by transmitting and receiving the distance measurement signal for each path between the station-side device (COT) and the remote device (RT). Here, the distance measurement signal may have a separate pattern that is distinguished from the optical signal of the PON MAC processing unit. As a method, it may be considered to include information indicating that the measurement signal is included in the header of the measurement signal packet. Alternatively, it may be considered that the optical signal constituting the measurement signal is made in such a manner that the intensity of the signal is adjusted according to a series of time intervals.

The method of measuring the distance is as follows. When the distance measuring unit 110 transmits the distance measurement signal to the remote device RT through the country-side device COT, the transmitted distance measurement signal is reflected by the remote device RT, and this is again applied to the country-side device COT. ) Receives. At this time, if the distance measurement signal is measured for the round trip between the station-side device (COT) and the remote device (RT), it is possible to obtain the distance to the optical path between the country-side device (COT) and the remote device (RT).

Here, the time for the distance measurement signal to and from the station-side device (COT) and the remote device (RT) is defined as Round Trip Time (RTT), and finally the interval may be expressed as Equation 1 below.

Here, RTT refers to Round Trip Time, which is a time for the ranging signal to and from the station-side device (COT) and the remote device (RT), where Ve represents the speed of the ranging signal and may be 2 * 10 ⁵ days. have.

The distance for each of the plurality of paths can be known by performing the distance measuring method for each of the plurality of paths between the office-side apparatus COT and the remote device RT.

Next, the path distance analyzer 120 analyzes the measured distance, and selects the distance of the longest path among the measured paths. In this way, the path distance analyzer 120 selects the distance of the longest path, so that when the TDM PON MAC ranging is required, the MAC ranging is performed based on the longest path distance.

Next, the distance difference calculator 130 calculates the distance difference value Delay _i for each path by comparing the distance R _max of the selected longest path and the respective path distances to the optical termination device (OLT) 200. send. Here, the distance difference value (Delay _i ) for each path is compared with the actual length (R _i ) and the longest path length (R _max ) of each path, and the actual length (R _i ) of each path from the length (R _max ) of the longest path. Mean difference value minus

The distance difference value Delay _i calculated as described above may be transmitted to the optical termination device (OLT) 200 through a transmitter (not shown) included in the distance corrector.

Next, the optical termination device (OLT) 200 receives the distance difference value Delay _{i for each} path from the distance correcting unit 100, converts it into a time delay value Td _i , and then controls an uplink signal transmission timing. Up-date equalization delay information, and transmit the gate control information reflecting the updated equalization delay information to the optical subscriber end (ONT).

More specifically, the optical termination apparatus (OLT) 200 converts the distance difference value Delay _i for each path into a time delay value Td _{i as} shown in Equation 2 below.

Here, Td _i = time delay value, Delay _i is the distance difference value for each path, Ve is the transmission speed of the ranging signal in the optical path.

On the other hand, while the optical termination device (OLT) 200 has been described as an example of converting the distance difference value Delay _i for each path to the time delay value Td _i , the distance correction unit 100 is differently The distance difference value Delay _{i for each} path may be converted into a time delay value Td _i , and then transmitted to the optical termination device 200.

Next, the method of updating the equalization delay information by the optical termination device (OLT) 200 is as shown in Equation 3 below.

Here, Ted _New denotes updated equalization delay information (Ted), Ted _Old denotes existing equalization delay information before updating, and Td _i denotes a time delay value.

When the optical termination device (OLT) 200 transmits the gate control information reflecting the up-date equalization delay information to the optical subscriber end (ONT) 300, the optical subscriber end 300 is an uplink signal. By delaying the transmission timing of the distance compensation according to the distance difference value for each path can be performed.

As such, each path is normalized based on the longest path by performing distance compensation according to the distance difference value Delay _i for each path. By preventing the virtual length from changing, it prevents collision between upstream signals, and from the standpoint of the optical termination device (OLT), it is recognized that all transmitted signals are transmitted through the same path length, so that separate MAC ranging due to protection switching is performed. You can avoid doing this. By doing this, service interruption for Mac ranging can be minimized.

If a plurality of paths are normalized to a minimum length, when protection switching is performed to a path having a longer length, the TDM PON has no choice but to perform MAC ranging again. The same is true for normalization to medium lengths.

Meanwhile, in FIG. 3, the distance corrector 100 is provided separately from the optical termination device (OLT) 200 as an example. Alternatively, the distance correction unit 100 may be included and included in the optical termination device (OLT) 200. have. For example, the optical termination device (OLT) 200 may be integrally provided by installing a program or a module having the same function as the above-described distance correction unit 100 in the optical termination device (OLT) 200. .

4 is a diagram illustrating an example of a method for calculating a distance difference value for each path of a time division multiple passive optical communication network according to the present invention.

As shown, first, when the distance correction unit 100 receives a path normalization request for protection switching (S1), it is checked whether there is a newly added detour path (S2).

If there is no newly added bypass path, the distance information database is searched and the distance difference value for each path is already provided to the optical terminator (OLT) 200, and the optical terminator (OLT) 200 is placed in the protection switching. The equalization delay information is updated by converting the distance difference value for each path of the corresponding path that is changed by the path into a time delay value, and configures gate control information to be transmitted to the optical subscriber base (ONT) 300 by reflecting the updated equalization delay information. (S2-N)

When there is no newly added bypass path, the optical termination device (OLT) 200 knows the path length normalized to the longest length and the path difference value of the path of the corresponding path that is changed by the protection switching. According to the equalization delay information reflected, the ONT 300 may delay the transmission timing with respect to the uplink signal to perform distance compensation to prevent collision between the uplink signals.

Therefore, it is not necessary to perform a separate MAC ranging to determine the path distance to the optical subscriber end (ONT).

If there is a newly added detour route, the distance measuring unit 110 measures the distance of the newly added detour route by transmitting and receiving a distance measurement signal. (S2-Y) Here, the distance of the newly added detour route Measuring the distance may be measured again the distance to the entire path, including the newly added detour path, but may be targeted only to the newly added detour path.

In the case of the entire path, the number of paths N is calculated for each path, and the distance R _{N for} each path is measured. (S3) The distance information for each path measured as described above is R _N. It is represented and stored.

Next, the path distance analysis unit 120 selects the distance R _max of the longest path among the distances for each path measured in the measured R _N (S4). The distance of the longest path can be selected by selecting the maximum value R _max among R _N.

Next, the distance difference calculator 130 compares the distance of the selected longest path (R _max ) with the actual distance (R _i ) of each path, and calculates each path by calculating Delay _i = R _max -R _i . The distance difference value Delay _i is calculated (S6). As a result, each normalized length R _norm is expressed as a sum of the distance difference value Delay _i and the actual path distance R _{i for} each path, so that the distances of the plurality of paths have logically equal distances.

Since the process of calculating the distance difference value Delay _i for each path must be compared with the maximum value R _max and the distance R _i of each path, the process is repeated by the number of paths (Count N) (S5). , S7)

Next, when the calculation of the distance difference value Delay _i for each path is completed, normal distance information is stored in the distance information database 140 (S8).

Thereafter, the transmitter (not shown) included in the distance corrector 100 transmits a distance difference value Delay _i for each path to the optical termination device OLT 200 (S9).

Next, the optical termination device (OLT) 200 converts the distance difference value Delay _{i for each} path into a time delay value Td _i according to the above equation 2 to update the equalization delay information. However, unlike the above-described method, the distance difference value calculating unit 130 converts the distance difference value Delay _{i for each} path into a time delay value Td _i in advance, and the optical termination device OLT ( 200 may receive the time delay value Td _i from the distance corrector 100.

Next, the optical termination device (OLT) 200 updates the equalization delay information Ted according to Equation 3 described above. In this way, the first MAC ranging is performed using the updated equalization delay information (Ted _New ) (S11).

As such, when there is a path correction request due to protection switching when a new path is added, the first MAC ranging using the updated equalization delay information is performed by using the newly added path. This is because the distance of R _max ) may be changed.

In this case, since the longest path (R _max ), which is the virtual logical distance from the optical terminator (OLT) 200 to the optical subscriber end (ONT) 300, is changed, a single Mac to determine the virtual logical distance It is necessary to perform ranging. However, since the longest path (R _max ), which is a virtual logical distance, will be the same in the subsequent protection switching, there is no need to perform a separate MAC ranging, thereby providing a higher quality service.

Next, the optical termination device (OLT) 200 reflects the updated equalization delay information (Ted _New ) to the gate control information and transmits the gate control information to the optical subscriber end (ONT) 300. (S12)

Then, as described above, the optical subscriber stage (ONT) 300 performs distance compensation by delaying an upward signal by a distance difference value Delay _i of the corresponding path according to the zeit control information.

Meanwhile, the above-described embodiments of the present invention can be written as a program that can be executed in a computer, and can be implemented in a general-purpose digital computer that operates the program using a computer-readable recording medium. The computer-readable recording medium may be a magnetic storage medium (for example, a ROM, a floppy disk, a hard disk, a magnetic tape, etc.), an optical reading medium (for example, a CD-ROM, a DVD, an optical data storage device, etc.). And storage media such as carrier waves (eg, transmission over the Internet).

The above description is merely illustrative of the technical idea of the present invention, and various modifications, changes, and substitutions may be made by those skilled in the art without departing from the essential characteristics of the present invention. will be. Accordingly, the embodiments disclosed in the present invention and the accompanying drawings are not intended to limit the technical spirit of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by the embodiments and the accompanying drawings. . The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

1 is a configuration diagram briefly showing the configuration of a conventional general TDM-PON.

2 is a view for explaining an example of a time division multiple passive optical communication network according to the present invention;

3 is a view for explaining an example of the distance correction unit and the optical termination device (OLT) in FIG.

4 is a view for explaining an example of a method for calculating a distance difference value for each path of a time division multiple passive optical network according to the present invention;

Claims (18)

The distance difference value for each path for normalizing the distance of each of the plurality of paths is measured by measuring a plurality of path distances disposed between the station side device (COT) and the remote device (RT). Calculating a distance difference value for each path to be calculated; An equalization delay information updating step of converting the distance difference value for each path into a time delay value and then updating equalization delay information for controlling transmission timing of an uplink signal; And An equalization delay information transmission step of transmitting the updated equalization delay information to the optical subscriber terminal (ONT) by reflecting the updated equalization delay information in the optical subscriber terminal (ONT) to reflect the gate control information for controlling the optical transmitter; Path difference compensation method of a time division multiple passive optical network (TDM PON) comprising a. The method of claim 1, Computing the distance difference value for each path (a) measuring a distance for each path of each of the plurality of paths between the central office device (COT) and the remote device (RT); (b) selecting a distance of the longest path of each of the measured paths; And (c) calculating a distance difference value for each path to normalize each path based on the longest path by comparing the distances of the selected longest path with each path distance; Path difference compensation method of a time division multiple passive optical communication network comprising a. The method of claim 2, In the step (a) the distance for each path is And measuring the round trip time of a distance measurement signal for each of the plurality of paths from the station side device (COT) to the remote device (RT). The method of claim 2, In the step (a), the equation for measuring the distance for each path is represented by the following equation, the path difference compensation method of a time division multiple passive optical network. [Equation]

Here, RTT means Round Trip Time, which is the time when the ranging signal round trips between the COT and the remote device RT, and Ve means the transmission speed of the ranging signal in the optical path. The method of claim 1, The distance difference value for each path is Path difference compensation method of the time division multiple passive optical network (TDM PON) device, characterized in that stored in the distance information database included in the device. The method of claim 1, The equalization delay information updating step The path difference compensation method of the time division multiple passive optical communication network, characterized in that for converting the distance difference value for each path to a time delay value according to the following equation. [Equation]

Here, Td _i = time delay value, Delay _i is the distance difference value for each path, Ve is the transmission speed of the ranging signal in the optical path. The method of claim 1, The equalization delay information updating step Path difference compensation method of time division multiple passive optical communication network characterized in that for updating the equalization delay information according to the following equation. [Equation]

Here, Ted _New denotes updated equalization delay information, Ted _Old denotes existing equalization delay information before being updated, and Td _i denotes a time delay value. The method of claim 1, Path difference compensation method of time division multiple passive optical network After the equalization delay information transmitting step, the optical subscriber end (ONT) controlling the transmission timing of the uplink signal according to the gate control information; Path difference compensation method of a time division multiple passive optical network, further comprising a. The method of claim 8, The updated equalization delay information Computing a start time of the gate control information for controlling the timing of the transmission of the uplink signal path compensation method of a time division multiple passive optical network. The method of claim 1, Path difference compensation method of the time division multiple passive optical network If there is a path correction request due to protection switching in a state where a new path is added between the station side device (COT) and the remote device (RT) in addition to the plurality of paths, In the step of calculating the distance difference value for each path, the distance difference value for each path is calculated including the new path, After the equalization delay information updating step, performing initial MAC ranging by using the updated equalization delay information. Path difference compensation method of time division multiple passive optical communication network characterized in that the. The distance difference value for each path for normalizing the distance of each of the plurality of paths is measured by measuring a plurality of path distances disposed between the station side device (COT) and the remote device (RT). Distance correction unit for calculating and transmitting to the optical termination device (OLT); After receiving the distance difference value for each path from the distance corrector and converting it to a time delay value, the equalization delay information for controlling the transmission timing of the uplink signal is updated (up-date), and sent to the optical subscriber end (ONT). An optical termination device (OLT) for transmitting to the optical subscriber end (ONT) by reflecting on the gate control information for controlling the included optical transmitter; And An optical subscriber end (ONT) for controlling the transmission timing of the upward signal according to the gate control information received from the optical termination device (OLT); Time division multiple passive optical communication network comprising a. The method of claim 11, The distance correction unit A distance measuring unit measuring a distance for each path of each of the plurality of paths between the station side device (COT) and the remote device (RT); A path distance analyzer for selecting a distance of a longest path among the measured paths; And A distance difference calculation unit configured to compare the distances of the selected longest paths with respective path distances and calculate a distance difference value for each path for normalizing each path based on the longest path; Time division multiple passive optical communication network comprising a. 13. The method of claim 12, The distance measuring unit Time division multiple passive optical communication network, characterized in that for calculating the distance for each path by measuring the round trip time of the distance measurement signal for each of the plurality of paths from the station side device (COT) to the remote device (RT). The method of claim 11, The distance correction unit Time division multiple passive optical communication network further comprises a distance information database for storing the distance difference value for each path. The method of claim 11, The optical termination device (OLT) Time division multiple passive optical communication network, characterized in that for converting the distance difference value for each path to a time delay value according to the following equation. [Equation]

Here, Ted _New denotes updated equalization delay information, Ted _Old denotes existing equalization delay information before being updated, and Td _i denotes a time delay value. The method of claim 11, The optical termination device (OLT) Time division multiple passive optical communication network, characterized in that for updating the equalization delay information according to the following equation. [Equation]

Here, Ted _New denotes updated equalization delay information, Ted _Old denotes existing equalization delay information before being updated, and Td _i denotes a time delay value. The method of claim 11, The optical subscriber end (ONT) is Time division multiplexing, characterized in that to control the turn-on (Turn On) and turn-off (Turn Off) of the optical transmitter included in the optical subscriber end (ONT) in order to control the transmission timing of the uplink signal according to the gate control information Passive optical network. The method of claim 11, If there is a path correction request due to protection switching in a state where a new path is added between the station side device COT and the remote device RT in addition to the plurality of paths, The distance corrector calculates a distance difference value for each path including the new path, and the optical termination device (OLT) performs initial MAC ranging by using the updated equalization delay information. Time division multiple passive optical communication network characterized in that.

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