KR100872173B1 - Apparatus and method for supporting multiple transmission rates of PON system - Google Patents

Abstract

The present invention relates to a method and apparatus for supporting multiple transmission rates of a PON system, such that parallel data having data repeated a predetermined number of times according to a transmission rate to be generated by a PON network is output through a transmission interface of a plurality of lanes. A PON MAC unit configured to repeat the repeated data in the parallel data; And a serializer for latching parallel data provided through the transmission interface into a serial data clock to generate serial data having different data widths according to transmission rates, thereby generating ONU and OLT into a PON network. In the case of changing the transmission speed, the data width is adjusted internally without changing the clock, thereby reducing the cost and maximizing the efficiency of network operation.

PON, MAC, GEM, Interface, OLT, ONU

Description

Apparatus and method for supporting multiple transmission rates of PON system}

1 is a view schematically showing a general PON,

2a is a diagram illustrating a downlink packet flow of a general PON;

2b is a diagram illustrating an uplink packet flow of a general PON;

3 shows a typical ONU for handling PON packet transmissions,

4 schematically illustrates a PON in accordance with a preferred embodiment of the present invention;

5 illustrates an ONU for processing PON packet transmission according to an embodiment of the present invention;

6 is a diagram illustrating a relationship between a transmission interface for each PON transmission rate and parallel data output through the transmission interface according to an embodiment of the present invention; and

7 is a flowchart illustrating a method of varying a transmission rate of an ONU in a PON according to an exemplary embodiment of the present invention.

* Description of the symbols for the main parts of the drawings *

100: OLT 200: ONU

210: PON MAC unit 220: serialization unit

230: parallel input register 240: PLL

250: parallel shift register 260: clock generator

270: photoelectric conversion unit 300: optical splitter

The present invention relates to a method and apparatus for supporting multiple transmission rates of a PON system, and more particularly to a method and apparatus for supporting multiple transmission rates of a PON system for easily varying the transmission rate to be generated in the PON network.

Generally, a passive optical network (hereinafter referred to as a 'PON') refers to a system that transmits a signal to an end user through an optical cable network. Such a PON is divided into a fiber to the curb (FTTC), a fiber to the building (FTTB), or a fiber to the home (FTTH) depending on where the terminal is processed.

In addition, the PON is composed of one optical line terminal (OLT) installed at a network, that is, a carrier, and a plurality of optical network units (ONUs) installed at a subscriber's premises or at an entrance facility. In general, up to 32 ONUs are connected to one OLT, and a point-to-multipoint connection forms a distributed tree topology.

1 is a view schematically showing a general PON.

FIG. 2A illustrates a downlink packet flow of a general PON, and FIG. 2B illustrates an uplink packet flow of a general PON.

Referring to FIG. 1, a PON has a configuration in which one OLT 10 connected to a network and a plurality of ONUs 20 connected to a subscriber are connected through an optical splitter 30.

In this PON, as shown in FIG. 2A, all packets destined for the ONU 20 from the OLT 10 to the ONU 20 are transmitted according to the broadcasting method, and the packet to be received by the corresponding ONU 20 receiving the packet is transmitted. To filter. And, as shown in FIG. 2B, one PON is shared by each ONU 20 using several medium access methods for packet transmission from the ONU 20 to the OLT 10 (upward direction). Each packet is transmitted through the optical link of the network. In particular, the PON, which is defined as TDMA (Time Division Multiple Access), applies a time division approach to uplink packet transmission so that each ONU 20 transmits a packet at a time allowed by the OLT 10.

Therefore, in PON, different transmission methods such as multiplexing transmission method and broadcasting transmission method are performed for each uplink and downlink transmission, which are not used by the existing network. Correspondingly, a medium access control layer (hereinafter, referred to as 'MAC') is newly defined.

On the other hand, the PON defines the up and down speed between the OLT (10) and ONU (20) differently according to the system configuration in order to freely determine the up speed according to the network operation. For example, the Gigabit-capable Passive Optical Network (GPON) allows the uplink to be implemented at 2.5Gbps, 1.25Gbps or 622Mbps transmission rates when the downlink is 2.5Gbps.

Next, look at the center of the ONU (20) PON that implements different transmission rates according to the system configuration.

3 is a diagram illustrating a general ONU for processing PON packet transmissions.

As shown in FIG. 3, the ONU 20 includes a PON MAC unit 21, a serializer 22, and a photoelectric converter 23 to process PON packet transmission.

Here, the PON MAC unit 21 reconstructs and outputs the general packet generated from the subscriber connected to the ONU 20 into parallel data of a PON frame used only in the PON. The serialization unit 22 converts the parallel data output from the PON MAC unit 21 into serial data, and the photoelectric conversion unit 23 converts the serial data, which is an electrical signal, into an optical signal, thereby converting the optical link into an optical link. To be transmitted to the OLT 10.

On the other hand, in the ONU 20 having such a configuration, the PON MAC unit 21 is implemented as an IC of digital logic such as an ASIC, an FPGA, etc., while the serializer 22 and the photoelectric converter 23 are mostly analog circuits. As implemented by the combination, the transmission rate of the PON link is determined by the hardware configuration by the analog circuit combination of the ONU 20.

Therefore, PON, which can implement a transmission rate of 2.5 Gbps at 622 Mbps, is set to a transmission rate that is already set in hardware even if the ONU 20 attempts to change the transmission rate currently being processed according to the network implementation. setting) has a problem that the transmission rate can not be changed variably without replacing the hardware of the ONU 20.

In addition, this problem is similarly generated not only in the ONU 20 but also in the OLT 10.

An object of the present invention for solving the above problems is to provide a method and apparatus for supporting multiple transmission rates of the PON system to variably operate the transmission rate of the PON system without hardware replacement of the ONU and OLT.

An apparatus for supporting multiple transmission rates of a PON system according to an embodiment of the present invention for achieving the object of the present invention as described above, the parallel having a data that is repeated a predetermined number of times according to the transmission rate to be generated in the PON network A PON MAC unit configured to output data through a transmission interface of a plurality of lanes, wherein the repeated data are arranged adjacent to each other in the parallel data; The parallel data provided through the transmission interface is latched with a serial data clock to include serial data having different data widths for each transmission speed.

The PON MAC unit converts a general packet provided from a telecommunication company network or a subscriber network into a PON frame, and converts the PON frame into the parallel data.

The PON MAC unit may output the parallel data through the transmission interface of 16 lanes synchronized with a 155 Mbps clock for each lane.

When the PON MAC unit is to generate a transmission rate of 2.5 Gbps, the PON MAC unit generates parallel data including 16 bits of different data using the 16-lane transmission interface.

When the PON MAC unit is to generate the transmission rate of 1.25Gbps, the 16-lane transmission interface generates parallel data formed by copying two different 8-bit data into two.

When the PON MAC unit is to generate a transmission rate of 622 Mbps, the 16-lane transmission interface generates parallel data formed by copying four different data of 4 bits each.

The serializer generates a serial data clock of 2.5 GHz.

Preferably, the apparatus for supporting multiple transmission rates of the PON system may further include a photoelectric conversion unit converting the electrical signal of the serial data into an optical signal and transmitting the converted optical signal to the PON network.

Preferably, the apparatus for supporting multiple transmission rates of the PON system may further include a clock generator configured to provide a preset reference clock to the serializer so that the serializer generates the serial data clock using the reference clock. do.

 According to another embodiment of the present invention for achieving the object of the present invention as described above, the multiple transmission rate support method of the multiple transmission rate support apparatus of the PON system, the transmission data according to the transmission rate to be generated in the PON network Repeating the set number of times; Parallelizing data by arranging the repeated data to be adjacent to each other; And latching the parallel data with a preset serial data clock to generate serial data having different data widths for each transmission rate.

The repeating of the transmission data a predetermined number of times may include converting a packet provided from a telecommunication company network or a subscriber network into a PON frame and generating the transmission data of the converted PON frame according to the transmission rate to be generated. It is characterized by repeating.

The parallelizing may include generating 16-bit parallel data synchronized with a 155 Mbps clock.

The parallelizing may include generating 16-bit parallel data using transmission data in units of 16 bits when the transmission rate to be generated is 2.5 Gbps.

In the parallelizing step, when the transmission rate to be generated is 1.25Gbps, 16-bit parallel data is generated by copying two pieces of 8-bit transmission data.

In the generating of the parallel data, when the transmission rate to be generated is 622 Mbps, the parallel data of 16 bits may be generated by copying four pieces of transmission data in units of 4 bits.

The latching of the parallel data with a preset serial data clock may include latching the parallel data with a 2.5 GHz serial data clock.

Preferably, the method for supporting multiple transmission rates of the PON system further includes converting the generated electrical signal of the serial data into an optical signal and transmitting it to a PON network.

DETAILED DESCRIPTION Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, in describing in detail the operating principle of the preferred embodiment of the present invention, if it is determined that the detailed description of the related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

In addition, the same reference numerals are used for parts having similar functions and functions throughout the drawings.

4 schematically illustrates a PON according to an exemplary embodiment of the present invention.

As shown in FIG. 4, the PON includes a single optical line terminal (OLT) 100 installed at a telecommunication company and a plurality of optical network units (ONUs) installed at a subscriber's premises or an entrance facility. (200) to form a distributed topology configuration of the tree structure in a point-to-multipoint connection method via the optical splitter 300 between the OLT 100 and the ONU (200).

The OLT 100 and the ONU 200 generating a variable transmission rate in such a PON convert a packet provided from a carrier network and a subscriber network into a PON frame, and transmit the data to be converted into a PON frame. By repeating the preset number of times according to the speed, parallel data in different bit units is generated for each transmission speed. Here, the repeated data are disposed adjacent to each other, and the parallel data may be synchronized to a 2.5 Gbps clock as a whole.

That is, the OLT 100 and the ONU 200 generate 2.5 Gbps parallel data having data repeated a predetermined number of times.

The OLT 100 and the ONU 200 may latch the parallel data with a serial data clock and convert the parallel data back into converted serial data having different data widths for each transmission rate at which the parallel data is to be generated. .

That is, the OLT 100 and the ONU 200 generate serial data having different data widths at different transmission speeds as data that is repeated adjacent to repeated data in the serial data latched by the serial data clock is regarded as one data. .

For example, the OLT 100 and the ONU 200, which intends to generate a transmission rate of 2.5 Gbps, are 16-bit parallel data having a 16-bit unit for data provided and converted from a carrier network and a subscriber network. The parallel data may be converted into serial data having a transmission rate of 2.5 Gbps using a serial data clock.

In addition, the OLT 100 and the ONU 200, which intends to generate a transmission rate of 1.25 Gbps, generate 16-bit parallel data having an 8-bit unit by repeating each data twice, and using a serial data clock. The parallel data may be converted into serial data having a transmission rate of 1.25 Gbps.

In addition, the OLT 100 and the ONU 200 which intend to generate a transmission rate of 622 Mbps generate 16 bits of parallel data having a 4-bit unit by repeating each data four times, and using the serial data clock. Parallel data may be converted into serial data having a transmission rate of 622 Mbps.

On the other hand, the OLT 100 and ONU 200, which generate transmission rates of 2.5 Gbps, 1.25 Gbps, and 622 Mbps, can allow 16-bit parallel data to have a transmission rate of 2.5 Gbps. That is, the OLT 100 and the ONU 200 may generate parallel data in which one bit is synchronized with a 155 Mbps clock.

Next, in detail looking at the variable transmission rate generation method of the PON having such a configuration and other detailed configuration of the generation, look at the ONU (200) as an embodiment.

5 illustrates an ONU for processing PON packet transmission according to an exemplary embodiment of the present invention.

As shown in FIG. 5, the ONU 200 that processes PON packet transmission may include a PON MAC unit 210, a serializer 220, a clock generator 260, and a photoelectric converter 270. .

The PON MAC unit 210 performs a function of reconstructing the general packet generated from the subscriber connected to the ONU 200 into parallel data of the PON frame. The PON MAC unit 210 may output the reconstructed parallel data through a transmission interface of a plurality of lanes, and may allow the transmission interface to be configured as a differential signal synchronized with a preset clock. FIG. 5 illustrates an example in which the PON MAC unit 210 outputs parallel data by using a 16-bit transmission interface synchronized with a 155 Mbps clock for each lane.

The serializer 220 configures the parallel input register 230, the PLL 240, and the parallel shift register to convert parallel data output from the PON MAC unit 210 into serial data.

The serializer 220 receives the parallel data output from the PON MAC unit 210 through the parallel input register 230 and temporarily stores the parallel data in the parallel input register 230, and the frequency detector, the phase detector, and the loop. The PLL 240 including at least one of a filter, an amplifier, and a voltage controlled oscillator generates a preset serial data clock using a reference clock generated from the clock generator 260.

For example, when the serializer 220 intends to generate serial data at a 2.5 Gbps transmission rate, the PLL 240 receives a low frequency reference clock such as 155.52 MHz or 77.76 MHz from the clock generator 260 to obtain parallel data. Generate a 2.5GHz serial data clock that can be multiplexed with serial data at high speed.

Accordingly, the parallel shift register 250 of the serialization unit 220 may convert parallel data temporarily stored in the parallel input register 230 into serial data using the serial data clock generated by the PLL 240.

That is, the parallel shift register 250 receives parallel data from the parallel input register 230 and latches the parallel data serially by one bit with a serial data clock generated by the PLL 240. To change. For example, when the parallel shift register 250 is provided with 16 lanes of data synchronized with the 155 Mbps clock from the parallel input register 230, the serial data clock generated from the PLL 240, that is, through a 2.5 GHz clock, is provided. Each lane is sequentially latched to convert the parallel data into serial data.

Here, the parallel shift register 250 may latch the parallel data in the order of lane 0 to lane 15 or the lane 15 to lane 0 to serialize the data. In the case of serializing data in the order of lane 0 to lane 15, after lane 15 Immediately back in lane 0. In addition, such a serialization order may be performed according to a predetermined appointment with the OLT 100.

The photoelectric conversion unit 270 converts an electric signal of serial data for each transmission rate to be generated into an optical signal and transmits it to a PON network.

On the other hand, the ONU 200 having such a configuration can control the transmission speed by adjusting only the data width of the parallel data while maintaining the same serial data clock.

That is, the ONU 200 outputs the parallel data having data repeated a predetermined number of times according to the transmission rate to be generated by the PON MAC unit 210 through the transmission interface of the plurality of lanes. ) Allows serial data of different data widths to be generated for each transmission rate.

For example, when the ONU 200 intends to generate a transmission speed of 1.25 Gbps, the same data is output twice along the adjacent lane from the 16-lane transmission interface of the PON MAC unit 210, thereby synchronizing to the 155 MHz clock. 8-bit parallel data may be output from the PON MAC unit 210 to the serializer 220. In addition, the ONU 200 causes the serializer 220 to latch the input 8-bit parallel data into a 2.5 GHz serial data clock to generate 1.25 Gbps serial data.

As another example, when the ONU 200 intends to generate a transmission rate of 622 Mbps, the same data is output four times along the adjacent lane from the 16-lane transmission interface of the PON MAC unit 210, thereby synchronizing to the 155 MHz clock. Parallel data in units of 4 bits may be output from the PON MAC unit 210 to the serializer 220. The ONU 200 allows the serializer 220 to latch the input 4-bit parallel data into a 2.5 GHz serial data clock to generate 622 Mbps serial data.

Accordingly, the ONU 200 defines a relationship between a transmission interface of the PON MAC unit 210 and parallel data output through the corresponding transmission interface regardless of the internal logic implementation of the PON MAC unit 210 as shown in FIG. 6. By doing so, it is possible to control the transmission speed without the exchange of components including the serialization unit 220.

6 is a diagram illustrating a relationship between a transmission interface for each PON transmission rate and parallel data output through the corresponding transmission interface according to an embodiment of the present invention.

In FIG. 6, 'Interface [n]' represents each parallel lane of the 16-bit transmission interface defined between the PON MAC unit 210 and the serializer 220, and 'Data [n]' represents the PON MAC unit 210 from the PON MAC unit 210. Represent each data to be processed in parallel.

Referring to FIG. 6, the ONU 200 displays 'Data [n' on each of the parallel lanes of the transmission interface, that is, 'Interface [0]' through 'Interface [15]' according to the transmission rate to be generated. ] 'Can be different data or data that is repeated the same twice or four times adjacent.

That is, when the ONU 200 intends to generate a data rate of 2.5 Gbps, 'Data [15: 0]' can be loaded on each parallel lane of a transmission interface, and a data rate of 1.25 Gbps or 622 Mbps is generated. In this case, as shown in FIG. 6, data of 'Data [7: 0]' or 'Data [3: 0]' may be repeatedly loaded adjacent to each parallel lane of the transmission interface.

Accordingly, the ONU 200 may maintain the actual data width of the transmission interface at 16 regardless of the transmission rate to be generated.

In addition, the ONU 200 maintains a transmission rate of parallel data input and output to the parallel input register 230 of the serialization unit 220 at 2.5 Gbps, and transmits the data to the PON network according to the repeated data output of the transmission interface. The actual data rate can be 1/2 or 1/4 of the 2.5 Gbps.

In more detail, the ONU 200 transmits one bit of data to the PON network by transmitting the same data latched to the 2.5 GHz clock twice or four times, or the data latched to the 1.25 GHz or 622 MHz clock. As the transmission is the same, the 2.5 Gbps parallel data outputted from the PON MAC unit 210 to the serialization unit 220 to generate a 1.25 Gbps or 622 Gbps transmission rate is' Data [7: 0] 'or' Data [3: 0] ', and the data are repeated two or four times adjacently to adjust the bandwidth of the parallel data, the same data latched on the 2.5GHz clock is finally It can be sent one or four times. From this, the ONU 200 variably generates transmission rates of 2.5 Gbps, 1.25 Gbps and 622 Mbps.

7 is a flowchart illustrating a method of varying a transmission rate of an ONU in a PON according to an exemplary embodiment of the present invention.

Referring to FIG. 7, the ONU 200 variably generates a PON packet transmission rate. First, the ONU 200 receives a packet from a subscriber network (S101) and converts the received packet into a PON frame (S102).

As such, the ONU 200 checks the transmission rate to be generated by the PON network (S103), and when the transmission rate is 2.5Gbps, the converted PON frame is converted into parallel data in units of 16 bits (S104).

The ONU 200 latches the parallel data in units of 16 bits with a preset serial data clock (S105), and converts the parallel data into serial data having a 2.5Gbps transmission rate (S106).

On the other hand, if the transmission rate to be generated in the PON network is 1.25Gbps, the ONU 200 converts the PON frame converted in step 102 into 8-bit units in parallel (S107). Here, in generating parallel data in units of 8 bits, the ONU 200 causes each data of 'Data [7: 0]' to be repeated twice adjacently, so that the entire parallel data is composed of 16 bits.

The ONU 200 latches parallel data in units of 8 bits with a preset serial data clock (S108), and converts the parallel data into serial data having a transmission rate of 1.25Gbps (S109).

In addition, when the transmission rate to be generated in the PON network is 622Mbps, the ONU 200 converts the PON frame converted in step 102 into parallel data in units of 4 bits (S110). Here, in generating parallel data in units of 4 bits, the ONU 200 causes each data of 'Data [3: 0]' to be repeated four times adjacently, so that the entire parallel data is composed of 16 bits.

Then, the ONU 200 latches parallel data in units of 4 bits with a preset serial data clock (S111), and converts the parallel data into serial data at a 622Mbps transmission rate (S112).

The ONU 200 generating serial data for each transmission rate to be generated as described above converts the electrical signal of the serial data into an optical signal (S113), and then transmits the serial data of the converted optical signal to the PON network. (S114).

The present invention described above is not limited to the above-described embodiments and the accompanying drawings, and it is common in the art that various substitutions, modifications, and changes can be made without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art.

In particular, the present invention describes an ONU as an embodiment in the PON, but the same configuration as the above-described ONU may be equally applied to the OLT.

As described above, a method and an apparatus for supporting multiple transmission rates of a PON system according to the present invention, when the ONU and the OLT vary the transmission rate to be generated by the PON network, by internally adjusting the data width without changing the clock, It has the effect of reducing the cost and maximizing the efficiency of network operation.

Claims (17)

PON MAC which allows parallel data having data repeated a predetermined number of times according to a transmission rate to be generated by a PON network through a transmission interface of a plurality of lanes, wherein the repeated data are arranged adjacent to each other in the parallel data. part; And And a serializer for latching parallel data provided through the transmission interface into a serial data clock to generate serial data having a different data width for each transmission rate. The method of claim 1, The PON MAC unit, And converting a general packet provided from a carrier network or a subscriber network into a PON frame and converting the PON frame into the parallel data. The method of claim 1, The PON MAC unit, And outputting the parallel data to the serializer through the 16-lane transmission interface synchronized with the 155 Mbps clock for each lane. The method of claim 3, The PON MAC unit, In the case of generating a transmission rate of 2.5 Gbps, the apparatus for supporting multiple transmission rates of a PON system, wherein parallel data including 16 bits of different data is generated using the 16-lane transmission interface. The method of claim 3, The PON MAC unit, In order to generate a transmission rate of 1.25Gbps, multiple data rate support apparatus of a PON system, characterized in that to generate the parallel data consisting of two copies of the 8-bit different data to each of the 16 lanes transmission interface . The method of claim 3, The PON MAC unit, In the case of generating a transmission rate of 622 Mbps, the multi-rate supporting apparatus of the PON system, characterized in that to generate the parallel data consisting of four copies of each of the four different data to the four-lane transmission interface. The method of claim 3, The serializer, Apparatus for supporting multiple data rates of a PON system, characterized by generating a serial data clock of 2.5 GHz. The method of claim 1, And a photoelectric conversion unit converting the electrical signal of the serial data into an optical signal and transmitting it to a PON network. The method of claim 1, And a clock generator configured to provide a preset reference clock to the serializer so that the serializer generates the serial data clock using the reference clock.  In the multiple rate support method of the multiple rate support apparatus of the PON system, Repeating transmission data a predetermined number of times according to a transmission rate to be generated in a PON network; Parallelizing data by arranging the repeated data to be adjacent to each other; And And latching the parallel data with a preset serial data clock to generate serial data having a different data width for each transmission rate. The method of claim 10, Repeating the transmission data a predetermined number of times, And converting a packet provided from a carrier network or a subscriber network into a PON frame, and repeating the transmission data of the converted PON frame according to the transmission rate to be generated. The method of claim 10, The parallelizing step is, 16-bit parallel data synchronized to the 155Mbps clock, characterized in that the multi-rate supporting method. The method of claim 10, The parallelizing step is, And when the transmission rate to be generated is 2.5 Gbps, generating 16-bit parallel data using 16-bit transmission data. The method of claim 10, The parallelizing step is, When the transmission rate to be generated is 1.25Gbps, the multi-rate support method, characterized in that 16-bit parallel data is generated by copying the transmission data of 8-bit unit to two. The method of claim 10, The parallelizing step is, When the transmission rate to be generated is 622 Mbps, the multi-rate support method characterized in that the parallel data of 16 bits is generated by copying the transmission data of the 4-bit unit to four. The method of claim 10, The latching of the parallel data to a preset serial data clock may include: And latching the parallel data with a 2.5 GHz serial data clock. The method of claim 10, And converting the generated electrical signal of serial data into an optical signal and transmitting the converted electrical signal to a PON network.

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