JP4710444B2 - Optical transmission system and method, and optical termination device - Google Patents

Description

  The present invention relates to an optical transmission system and method, and an optical termination device, and more specifically, can accommodate services of two types of data transmission rates in one-to-many data transmission such as a passive optical network (PON). The present invention relates to an optical transmission method and system, and an optical termination device.

  In the PON, an optical terminator (OLT) arranged in a center station and a plurality of optical terminators (ONUs) arranged in different user houses are connected by a passive optical transmission line. In EPON, a logical link (Logical Link) is set between the OLT and the ONU. By using this logical link, the OLT can transmit data to a specific ONU, and specify the ONU of the data transmission source. To do.

  In the conventional PON system, the data transmission rate on the optical transmission line connecting the OLT and the ONU is constant, and an OLT and an ONU corresponding to one data transmission rate, for example, 1.25 Gbps are used.

  Recently, broadbandization has progressed, and there is a desire to enjoy higher-speed data transmission or communication even in PON. On the other hand, some users find that existing data transmission rates are sufficient.

  In this situation, users who want a high-speed service can be provided with higher-speed data transmission, and users who are satisfied with the existing service can use the existing data transmission rate service. PON system is desired. That is, a PON system that can support data transmission at different data transmission rates is desired. In other words, a PON system capable of mixing ONUs corresponding to different data rates is desired.

  Therefore, an object of the present invention is to provide an optical transmission system and method capable of mixing optical termination devices having different data transmission rates, and an optical termination device usable in such a method and system.

An optical transmission system according to the present invention includes a first user optical terminator corresponding to a first data rate and a second user optical terminator corresponding to a second data rate faster than the first data rate. and a plurality of user-side optical termination unit including, a center-side optical termination unit for connecting with the plurality of user-side optical termination unit via an optical transmission path, the data to be transmitted to the first user optical terminal equipment A center-side optical termination device that outputs to the optical transmission line at the first data rate and outputs data to be transmitted to the second user optical termination device to the optical transmission line at the second data rate. The center-side optical termination device is compatible with the first data rate with respect to both the first user optical termination device and the second user optical termination device. Rate A preamble generation device that generates an amble and a payload including data to be transmitted to the first user optical terminator are output at a rate corresponding to the first data rate and transmitted to the second user optical terminator. And a payload generation device that outputs a payload including data to be transmitted at a rate corresponding to the second data rate .

An optical transmission method according to the present invention includes a first user optical terminator corresponding to a first data rate and a second user optical terminator corresponding to a second data rate faster than the first data rate. and a plurality of user-side optical termination unit including, a center-side optical termination unit for connecting with the plurality of user-side optical termination unit via an optical transmission path, the data to be transmitted to the first user optical terminal equipment A center-side optical termination device that outputs to the optical transmission line at the first data rate and outputs data to be transmitted to the second user optical termination device to the optical transmission line at the second data rate. an optical transmission system comprising, the center-side optical terminal device, and outputting the unicast data into the first user optical terminal equipment to the optical transmission line in the first data rate, the center A step in which the side optical termination device outputs multicast or broadcast data including the first user optical termination device to the optical transmission line at the first data rate; Outputting unicast data to the user optical terminal device to the optical transmission line at the second data rate .

  An optical terminator according to the present invention includes a first user optical terminator corresponding to a first data rate and a second user optical terminator corresponding to a second data rate faster than the first data rate. An optical termination device that is connected to a plurality of user-side optical termination devices including an optical transmission line and transmits / receives data, to which of the first user optical termination device and the second user optical termination device However, a preamble generation device that generates a preamble at a rate corresponding to the first data rate, and a payload that includes data to be transmitted to the first user optical terminal device are rates corresponding to the first data rate. And a payload generation device that outputs a payload including data to be transmitted to the second user optical termination device at a rate corresponding to the second data rate. And wherein the door.

  According to the present invention, a higher-speed data transmission at the second data rate can be taken into the optical transmission system operated at the first data rate. In addition, since two types of data rates can coexist, more various services are possible.

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

  FIG. 1 shows a schematic block diagram of an embodiment of the present invention. An optical terminator (OLT) 10 disposed in the center station is connected to an optical coupler 14 via an optical fiber 12. The optical coupler 14 is also connected to optical terminal units (ONUs) 18-1 and 18-2 at user's homes via optical fibers 16-1 and 16-2, respectively. The optical coupler 14 divides the optical signal from the optical fiber 12 into two, and outputs the divided optical signals to the optical fibers 16-1 and 16-2. The optical coupler 14 also outputs optical signals from the optical fibers 16-1 and 16-2 to the optical fiber 12. Different wavelengths are used for upstream and downstream. A computer (PC) 20-1 is connected to the ONU 18-1, and a computer (PC 920-2 is connected to the ONU 18-2. The OLT 10 is also connected to the upper network via the edge router 22.

  In this embodiment, data transmission is based on a frame structure consisting of a preamble used exclusively for synchronization, a payload carrying the data itself, and an interframe gap IFG indicating separation from subsequent frames. For example, an Ethernet (registered trademark) Ethernet frame is stored in the payload. On the EPON system, a logical link is set between the ONU 10 and the OLTs 18-1 and 18-2 according to each service used (data transmission, IP telephone, IP method, etc.). , And is identified by the identification information LLID (Logical Link IDentifier). In one example, the preamble is 8 bytes, the payload is 64 to 1518 bytes, and the IFG is 12 bytes or more. When VLAN (Virtual LAN) is used, the maximum payload is 1522 bytes.

  In this embodiment, the ONU 18-1 is compatible with the existing 1 Gbps, and the ONU 18-2 is compatible with 2 Gbps. The OLT 10 supports both 1 Gbps and 2 Gbps. Although three or more ONUs can be connected to the PON system shown in FIG. 1, FIG. 1 shows a connection example in which a minimum number of ONUs are connected. When one ONU of a 1 Gbps-based PON system is changed to an ONU that supports 2 Gbps, the OLT is changed to an OLT 10 that supports both 1 Gbps and 2 Gbps.

  In this embodiment, in the case of unicast, the OLT 10 transmits data at 1 Gbps to the ONU 18-1 corresponding to 1 Gbps, and transmits data at 2 Gbps to the ONU 18-2 corresponding to 2 Gbps. In the case of multicast or broadcast, the OLT 10 transmits data at 1 Gbps that can be received by all ONUs. The ONU 18-1 corresponding to 1 Gbps transmits data to the OLT 10 at 1 Gbps, and the ONU 18-2 corresponding to 2 Gbps transmits data to the OLT 10 at 2 Gbps.

  In the GE (Gigabit Ethernet (Ethernet is a registered trademark))-PON system, the transmission side performs 8B / 10B conversion to convert 8 bits to 10 bits, and the reception side converts 10 bits to 8 bits. 10B / 8B conversion is performed to return to. An 8-bit length of 1 Gbps corresponds to a 10-bit length of 1.25 Gbps, and an 8-bit length of 2 Gbps corresponds to a 10-bit length of 2.5 Gbps.

  The OLT control device 30 of the OLT 10 corresponds to the processing capacity of each ONU 18-1, 18-2, that is, 1 Gbps when each ONU 18-1, 18-2 is connected to the optical fiber 16-1, 16-2, respectively. Or whether it corresponds to 2 Gbps, and the result is stored in the ONU management table 32. The OLT control device 30 also sets a logical link (Logical Link) corresponding to each use service (data transmission, IP telephone, IP method, etc.) of each ONU 18-1, 18-2, and an LLID (identification information). Logical Link IDentifier) is stored in the ONU management table 32.

  The downstream signal processing of this embodiment will be described. Data to be supplied to the ONU 18-1 or 18-2 is input to the network interface 34 from the higher level network via the edge router 22 in the form of an Ethernet frame, for example. The network interface 34 supplies the data from the edge router 22 to the buffer 36. The buffer 36 supplies input data to the 8B / 10B converter 38 and notifies the OLT controller 30 of data destination information (for example, a MAC address or an IP address).

  The oscillator 40 oscillates at 2.5 GHz, and its output clock is applied to the 1/2 frequency divider 42 and the switch 44. The output of the frequency divider 42 is applied to another input of the switch 44. The switch 44 applies either the output clock (2.5 GHz) of the oscillator 40 or the output clock (1.25 GHz) of the frequency divider 42 to the 8B / 10B converter 38 in accordance with a control signal from the OLT control device 30. To do. The 8B / 10B converter 38 converts the data from the buffer 36 from an 8-bit length code to a 10-bit length code at a speed according to the clock from the switch 44. The output clock of the frequency divider 42 is also applied to the preamble generator 46 and the IFG generator 48.

  When the destination is the ONU 18-2, the OLT control device 30 causes the switch 44 to select the output of the oscillator 40, and when the destination includes an ONU corresponding to 1 Gbps, for example, when the destination is only the ONU 18-1, or 18-1 18-2, the switch 44 is caused to select the output of the frequency divider 42. As a result, the 8B / 10B converter 38 outputs the payload data including the ONU 18-1 as a destination at 1.25 Gbps, and outputs the payload data for the ONU 18-2 as a destination at 2.5 Gbps.

  The OLT control device 30 collates the destination information from the buffer 36 with the ONU management table 32, reads the LLID of the destination, and supplies it to the preamble generation device 48. The preamble generation device 48 generates an 8-byte preamble that accommodates the LLID from the OLT control device 30 according to the 1.25 GHz clock from the frequency divider 42. However, here, the preamble generation device 48 generates a 10-bit preamble, that is, a preamble after 8B / 10B conversion. Thereby, the trouble of converting the preamble into 8B / 10B can be eliminated.

  The IFG generator 48 generates an interframe gap of 12 bytes or more at 1.25 Gbps according to the 1.25 GHz clock from the frequency divider 42. Again, the IFG generator 48 generates a 10-bit long interframe gap. Thereby, the trouble of converting the interframe gap to 8B / 10B can be eliminated.

  The multiplexing device 50 includes an 8-byte preamble output from the preamble generation device 46, a payload output from the 8B / 10B converter 38, and an interframe gap of 12 bytes or more output from the IFG generation device 48. The signals are multiplexed on the time axis in this order, and the obtained multiplexed signal is supplied to the electric / optical converter 52. FIG. 2 shows the relationship between the frame configuration and frequency of data transmitted to the ONU 18-1, and FIG. 3 shows the relationship between the frame configuration and frequency of data transmitted to the ONU 18-2. In the data frame directed to the ONU 18-1 corresponding to 1 Gbps, the rate of the preamble, payload, and interframe gap are all 1.25 Gbps, as shown in FIG. On the other hand, as shown in FIG. 3, the data frame for the ONU 18-2 corresponding to 2 Gbps has a preamble and interframe gap rate of 1.25 Gbps and a payload rate of 2.5 Gbps.

  The electrical / optical converter 52 converts the multiplexed signal from the multiplexer 50 into an optical signal, and supplies the optical signal to a wavelength division multiplexing (WDM) optical coupler 54. The WDM optical coupler 54 outputs the output optical signal of the electrical / optical converter 52 to the optical fiber 12. This optical signal is transmitted through the optical fiber 12 and enters the optical coupler 14. The optical coupler 14 divides the optical signal from the optical fiber 12 into two and outputs the divided optical signals to the optical fibers 16-1 and 16-2, respectively. In this way, the optical signal output from the electrical / optical converter 52 reaches the ONUs 18-1 and 18-2.

  The ONU 18-2 processes the optical signal from the optical fiber 16-2 as follows. That is, the optical signal from the optical fiber 16-2 is supplied to the optical / electrical converter 72 by the WDM optical coupler 70. The optical / electrical converter 72 converts the optical signal from the WDM optical coupler 70 into an electrical signal. This electric signal is applied to the data reproducing device 74 and the clock reproducing device 76. The clock regenerator 76 regenerates a clock (frequency 1.25 GHz) synchronized with the preamble of the input electric signal, and the multiplier 78 doubles the frequency of the clock regenerated by the clock regenerator 76. A 2.5 GHz clock output from the multiplier 78 is applied to the data reproducing device 74.

  The data reproducing device 74 captures the preamble and payload of the output electrical signal of the optical / electrical converter 72 according to the 2.5 GHz clock from the multiplier 78 and reproduces the preamble LLID and the Ethernet frame data of the payload. In other words, the data reproducing device 74 reads the LLID of the preamble with a double clock. The data reproducing device 74 supplies the read LLID to the ONU control device 80. The ONU control device 80 determines whether or not the signal is addressed to itself from the double-read LLID, and if it is addressed to itself, instructs the data reproduction device 74 to output the payload portion. The data reproduction device 74 is instructed to discard the data.

  The ONU control device 80 can determine whether the received signal is unicast or multicast / broadcast based on the LLID. Based on the determination result, whether the received signal is transmitted with the frame configuration shown in FIG. 2 or with the frame configuration shown in FIG. It is possible to determine whether it has been sent.

  When the received signal has the frame configuration shown in FIG. 2, the data reproducing device 74 takes in the payload of the received signal with the double clock, and the data overlaps. Therefore, the ONU control device 80 instructs the deduplication device 82 to thin out duplicate data (even bits) from the output data of the data reproducing device 74. In response to an instruction from the ONU control device 80, the deduplication device 82 removes even bits of the output data from the data reproducing device 74 and outputs only odd bits.

  On the other hand, when the received signal has the frame configuration shown in FIG. 3, the data reproducing device 74 has captured the payload of the received signal with the correct clock. The ONU control device 80 instructs the duplication removal device 82 to pass the output data of the data reproduction device 74 through the duplication device 82. In response to an instruction from the ONU control device 80, the deduplication device 82 outputs the output data of the data reproducing device 74 as it is.

  By providing the de-duplication device 82, a 2 Gbps signal and a 1 Gbps signal can be received without any trouble with a simple configuration.

  Of course, the data reproducing device 74 may reproduce the payload data at the frequency of the corresponding rate according to the determination result of the data rate of the data from the OLT 10. In this case, the deduplication device 82 is not necessary.

  The 10B / 8B converter 84 converts the output data of the deduplication device 82 from a 10-bit length to an 8-bit length, and supplies the conversion result to the network interface 86. The network interface 86 outputs the data from the 10B / 8B converter 84 to the computer 20-1 or the like in a predetermined format, for example, an Ethernet frame structure of 1000Base-T.

  On the other hand, when the optical signal having the frame structure shown in FIG. 2 is input, the ONU 18-1 can receive the signal by a known method. When the optical signal having the frame structure shown in FIG. 3 is input, the ONU 18-1 can process the preamble and interframe gap portions, but the payload portion is too high in frequency. However, in the first place, it is not necessary to receive the signal having the frame structure shown in FIG. Synchronization with the OLT 10 can be maintained using the preamble and the interframe gap.

  Next, processing of an upstream signal from the ONU 18-2 to the OLT 10 will be described. Data of the Ethernet frame from the computer 20-1 is supplied to the multiplexing device 92 via the network interface 86. The network interface 86 includes a buffer that temporarily holds data from the computer 20-1. The ONU control device 80 supplies the LLID assigned in advance according to the service of the ONU 18-2 to the preamble generation device 88, and the preamble generation device 88 generates a predetermined length preamble including the LLID, and sends it to the multiplexing device 92. Supply. The IFG generation device 90 generates an inter frame gap and supplies it to the multiplexing device 92.

  The multiplexing device 92 arranges data from the network interface 86 in the payload, and on the time axis, the preamble from the preamble generation device 88, the data from the network interface 86, and the interframe gap from the IFG generation device 90 are Multiplex in order. The 8B / 10B converter 94 converts the signal from the multiplexer 92 from an 8-bit length to a 10-bit length, and outputs the converted signal on a 2.5 Gbps basis. That is, the upstream signal generated by the ONU 18-2 has a preamble, a payload, and an IFG rate of 2.5 Gbps.

  The electrical / optical converter 96 converts the output data of the 8B / 10B converter 94 into an optical signal. The optical signal output from the electrical / optical converter 96 enters the WDM optical coupler 54 of the OLT 10 via the WDM optical coupler 70, the optical fiber 16-1, the optical coupler 14, and the optical fiber 12.

  The WDM optical coupler 54 supplies the optical signal from the ONU 18-2 to the optical / electrical converter 56, and the optical / electrical converter 56 converts the input optical signal into an electrical signal. This electrical signal is applied to the clock recovery device 58 and the data recovery device 60. The clock reproducing device 58 reproduces a clock (frequency 2.5 GHz) synchronized with the preamble of the input electric signal and applies it to the data reproducing device 60.

  The data reproduction device 60 takes in the preamble and payload of the electrical signal output from the optical / electrical converter 56 in accordance with the 2.5 GHz clock from the clock reproduction device 58, and reproduces the preamble LLID and the payload Ethernet frame data. The data reproducing device 60 supplies the read LLID to the OLT control device 30. The OLT control device 30 determines whether or not the signal is from the correct ONU (here, the ONU 18-2) from the LLID. If the signal is the correct signal, the OLT control device 30 instructs the data reproduction device 60 to output the payload portion, and the correct signal If not, the data reproducing device 60 is instructed whether or not the data is acceptable.

  The 10B / 8B converter 64 converts the data from the data reproduction device 60 from a 10-bit length to an 8-bit length, and supplies the conversion result to the network interface 34. The network interface 34 supplies the data from the 10B / 8B converter 64 to the edge router 22 in a predetermined format.

  In this way, uplink data is transmitted from the ONU 18-2 to the OLT 10 at 2 Gbps.

  The processing of the upstream signal from the ONU 18-1 to the OLT 10 will be described. Since the ONU 18-1 operates at the existing 1 Gbps, the upstream optical signal including the 1 Gbps preamble, payload, and IFG is output to the optical fiber 16-2. The upstream optical signal output by the ONU 18-1 simply differs in rate from the upstream optical signal output by the ONU 18-2. The upstream optical signal output from the ONU 18-1 enters the WDM optical coupler 54 of the OLT 10 through the optical fiber 16-1, the optical coupler 14, and the optical fiber 12.

  The WDM optical coupler 54 supplies the optical signal from the ONU 18-1 to the optical / electrical converter 56, and the optical / electrical converter 56 converts the optical signal into an electrical signal. This electrical signal is applied to the clock recovery device 58 and the data recovery device 60. The clock reproducing device 58 reproduces a clock (here, frequency 1.25 GHz) synchronized with the preamble of the input electric signal and applies it to the data reproducing device 60.

  In accordance with the 1.25 GHz clock from the clock recovery device 58, the data recovery device 60 captures the preamble and payload of the electrical signal output from the optical / electrical converter 56, and recovers the preamble LLID and the payload Ethernet frame data. The data reproducing device 60 supplies the read LLID to the OLT control device 30. The OLT control device 30 determines whether or not the signal is from the correct ONU (in this case, the ONU 18-1) based on the LLID. If it is a signal, the data reproduction device 60 is instructed to discard the data.

  The 10B / 8B converter 64 converts the data from the data reproduction device 60 from a 10-bit length to an 8-bit length, and supplies the conversion result to the network interface 34. The network interface 34 supplies the data from the 10B / 8B converter 64 to the edge router 22 in a predetermined format.

  In this way, upstream data is transmitted from the ONU 18-1 to the OLT 10 at 1 Gbps.

  When the size of the payload of the downstream signal transmitted from the OLT 10 to the ONU 18-2 is an odd number, the interframe gap is not synchronized with the preamble before the payload. In order to prevent this, for example, when the size of the payload is an odd number, the multiplexing device 50 adds 1 byte consisting of a reservation code (for example, K28.0) as padding or filling bytes at the end of the payload.

  A second embodiment of the present invention will be described. A schematic block diagram of the second embodiment is shown in FIG. Components that are changed from the embodiment shown in FIG. Changes from the embodiment shown in FIG. 1 will be described.

  In this embodiment, the frame configuration of the upstream signal from the ONU 18-2a corresponding to 2 Gbps to the OLT 10a is the configuration shown in FIG. That is, the rate of the uplink signal preamble and the interframe gap is set to the same rate in the ONU 18-2a supporting 2 Gbps and the existing ONU 18-1 supporting 1 Gbps, in this case, 1 Gbps.

  First, processing of an upstream signal from the ONU 18-2a to the OLT 10a will be described. The data of the Ethernet frame from the computer 20-1 is input to the 8B / 10B converter 94a via the network interface 86. The 8B / 10B converter 94a converts the data from the network interface 86 from an 8-bit length code to a 10-bit length code, and outputs the conversion result at 2.5 Gbps as payload data.

  The ONU control device 80a supplies the LLID corresponding to the transmission source of the data to be transmitted to the preamble generation device 88a. The preamble generation device 88a generates an 8-byte preamble at 1.25 Gbps that accommodates the LLID from the ONU control device 80a. However, here, the preamble generator 88a generates a 10-bit preamble, that is, a preamble after 8B / 10B conversion. Thereby, the trouble of converting the preamble into 8B / 10B can be eliminated.

  In addition, the IFG generation device 90a generates an interframe gap of 12 bytes or more at 1.25 Gbps. Again, the IFG generation device 90a generates an inter-frame gap having a 10-bit length. Thereby, the trouble of converting the interframe gap to 8B / 10B can be eliminated.

  The multiplexing device 92a includes an 8-byte preamble output from the preamble generation device 88a, a payload output from the 8B / 10B converter 94a, and an interframe gap of 12 bytes or more output from the IFG generation device 90a. The signals are multiplexed on the time axis in this order, and the obtained multiplexed signal is supplied to the electrical / optical converter 96. The format of the output signal of the multiplexer 92a is the same as that shown in FIG. 3, the preamble and interframe gap rate is 1.25 Gbps, and the payload rate is 2.5 Gbps.

  When the size of the payload after 8B / 10B conversion is an odd number, the interframe gap is not synchronized with the preamble before the payload. In order to prevent this, when the size of the payload is an odd number, the multiplexing device 92a adds 1 byte consisting of a reservation code (for example, K28.0) as padding or filling bytes at the end of the payload.

  The electrical / optical converter 96 converts the output data of the multiplexer 92a into an optical signal. The optical signal output from the electrical / optical converter 96 enters the WDM optical coupler 54 of the OLT 10a via the WDM optical coupler 70, the optical fiber 16-2, the optical coupler 14, and the optical fiber 12.

  In this embodiment, only the payload rate differs between the upstream signal from the ONU 18-2a and the upstream signal from the ONU 18-1. Accordingly, the upstream signal processing system of the OLT 10a is changed to the same configuration as the downstream signal processing system of the ONU 18-2. The operation will be specifically described.

  The WDM optical coupler 54 supplies the optical signal from the ONU 18-2a to the optical / electrical converter 56, and the optical / electrical converter 56 converts the input optical signal into an electrical signal. This electric signal is applied to the clock recovery device 58 and the data recovery device 60a. The clock regenerator 58 regenerates a clock (frequency 1.25 GHz) synchronized with the preamble of the input electric signal. The multiplier 59a doubles the frequency of the clock regenerated by the clock regenerator 58. A 2.5 GHz clock output from the multiplier 59a is applied to the data reproducing device 60a.

  The data reproducing device 60a takes in the preamble and payload of the electrical signal output from the optical / electrical converter 56 according to the 2.5 GHz clock from the multiplier 59a, and reproduces the LLID of the preamble and the Ethernet frame data of the payload. In other words, the data reproducing device 60a reads the LLID of the preamble with a double clock. The data reproducing device 60a supplies the read LLID to the OLT control device 30a. The OLT control device 30a determines whether or not the data is transmitted from the correct ONU from the double-read LLID, and if so, instructs the data reproduction device 60a to output the payload portion, and correctly If not, the data reproduction device 60a is instructed to discard the data.

  The OLT control device 30a can determine whether the rate of the payload of the uplink signal is 1.25 Gbps or 2.5 Gbps from the source of the uplink signal. Specifically, the rate of the payload of the upstream signal from the ONU 18-2a is 2.5 Gbps. In this case, the data reproducing device 74 has captured the payload of the upstream signal with the correct clock. In this case, the OLT control device 30a instructs the deduplication device 62a to pass through the output data of the data reproducing device 60a for the upstream signal from the ONU 18-2a. The deduplication device 62a outputs the output data of the data reproduction device 60a as it is in accordance with the instruction from the OLT control device 30a.

  On the other hand, the rate of the payload of the upstream signal from the ONU 18-1 is 1.25 Gbps. In this case, the data reproduction device 74 takes in the payload of the upstream signal with the double clock, and the data overlaps. Therefore, the OLT control device 30a instructs the deduplication device 62a to thin out the duplicate data (even bits) from the output data of the data reproducing device 60a for the upstream signal from the ONU 18-2. In accordance with an instruction from the OLT control device 30a, the deduplication device 62a discards the even bits of the output data of the data reproducing device 60a and outputs the odd bits as they are.

  By providing the deduplication device 62a, the OLT 10a can process two types of upstream signals with different rates of the payload portion.

  Of course, according to the result of determining the data rate of the data from the ONUs 18-1 and 18-2a, the data reproducing device 60a may reproduce the payload data at the frequency of the corresponding rate. In this case, the deduplication device 62a is not necessary.

  The 10B / 8B converter 64 converts the data from the deduplication device 62a from a 10-bit length to an 8-bit length, and supplies the conversion result to the network interface 34. The network interface 34 supplies the data from the 10B / 8B converter 64 to the edge router 22 in a predetermined format.

  In this way, the OLT 10a can similarly process uplink data with a data rate of 2 Gbps from the ONU 18-2a and uplink data with a data rate of 1 Gbps from the ONU 18-1.

  In the first and second embodiments, the ONUs 18-2 and 18-2a transmit at least the payload portion of the uplink signal at 2.5 Gbps. However, in order to maintain compatibility, the transmission of 1.25 Gbps can be selected. It is preferable to keep it. This is because an OLT that can only support 1 Gbps may still be used.

  Although the invention has been described with reference to specific illustrative embodiments, various modifications and alterations may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. This is obvious to an engineer in the field to which the present invention belongs, and such changes and modifications are also included in the technical scope of the present invention.

It is a schematic block diagram of the first embodiment of the present invention. It is a frame structure figure of the downstream signal with respect to the low-speed ONU18-1. It is a frame structure figure of the downstream signal with respect to high-speed ONU18-2. It is a schematic block diagram of the second embodiment of the present invention.

10, 10a: Optical termination device (OLT)
12: Optical fiber 14: Optical couplers 16-1, 16-2: Optical fibers 18-1, 18-1a, 18-2: Optical termination unit (ONU)
20-1, 20-2: Computer 22: Edge router 30, 30a: OLT control device 32: ONU management table 34: Network interface 36: Buffer 38: 8B / 10B converter 40: Oscillator 42: Frequency divider 44 : Switch 46: preamble generator 48: IFG generator 50: multiplexer 52: electrical / optical converter 54: wavelength division multiplexing (WDM) optical coupler 56: optical / electrical converter 58: clock recovery device 59a: multiplier 60 60a: Data recovery device 62a: Deduplication device 64: 10B / 8B converter 70: WDM optical coupler 72: Optical / electrical converter 74: Data recovery device 76: Clock recovery device 78: Multiplication device 80, 80a: ONU control Device 82: Deduplication device 84: 10B / 8B converter 86: Network interface 8,88A: preamble generating unit 90, 90a: IFG generator 92,92A: multiplexer 94,94a: 8B / 10B converter 96: Electrical / optical converter

Claims (15)

The first user optical terminator (18-1) corresponding to the first data rate and the second user optical terminator (18-2, 18) corresponding to the second data rate faster than the first data rate. A plurality of user-side optical terminators including 18-2a);
A center-side optical termination device (10 , 10a) connected to the plurality of user-side optical termination devices via an optical transmission line (12, 14, 16-1 , 16-2) , the first user light Data to be transmitted to the terminating device (18-1) is output to the optical transmission line at the first data rate, and data to be transmitted to the second user optical terminating device (18-2, 18-2a). center side optical termination unit that outputs to the optical transmission line at the second data rate
An optical transmission system comprising:
The center side optical terminator is
Preamble of a rate corresponding to the first data rate for both the first user optical terminal device (18-1) and the second user optical terminal device (18-2, 18-2a). A preamble generator (46) for generating
A payload including data to be transmitted to the first user optical terminator (18-1) is output at a rate corresponding to the first data rate, and the second user optical terminator (18-2, 18) is output. -A) A payload generating device (38) for outputting a payload including data to be transmitted at a rate corresponding to the second data rate
An optical transmission system comprising: The optical transmission system according to claim 1 , wherein the payload data generation device includes a code length converter (38) for converting data to be transmitted into a predetermined code length. The center-side optical terminator further has either data to be transmitted to the first user optical terminator (18-1) or the second user optical terminator (18-2, 18-2a). The optical transmission system according to claim 1 or 2 , further comprising an interframe gap generating device (48) for generating an interframe gap at a rate corresponding to the first data rate. The center side optical terminator is further
A first light receiver (56) for converting an optical signal input from the user optical terminal device (18-1, 18-2a) via an optical transmission line into an electrical signal;
A first data reproduction device (60a) for reproducing an electrical signal output from the first light receiver (56) at a frequency corresponding to the second data rate;
A first discriminating device (30a) for discriminating whether the data rate of data from the user optical terminal device (18-1, 18-2a) is the first data rate or the second data rate;
When the data rate of the data from the user optical terminal device (18-2a, 18-1) is the second data rate, duplicate data is removed from the reproduced data by the first data reproducing device (60a). Deduplication device (62a)
The optical transmission system according to any one of claims 1 to 3 , further comprising: The center side optical terminator is
A first light receiver (56) for converting an optical signal input from the user optical terminal device (18-2a, 18-1) through an optical transmission line into an electrical signal;
A first discriminating device (30a) for discriminating whether the data rate of data from the user optical terminal device (18-2a, 18-1) is the first data rate or the second data rate;
When the data rate of the data transmitted from the user optical terminal device (18-2a) is the first data rate, the electrical signal output from the first light receiver (72) is the first data rate. When the data rate of the data reproduced from the frequency according to the data rate and transmitted from the user optical terminal device (18-1) is the second data rate, from the first light receiver (72). the optical transmission system according to any one of claims 1 to 3 an electric signal output, characterized by comprising a data reproducing apparatus for reproducing at a frequency corresponding to said second data rate. The second user optical terminator is
A second light receiver (72) for converting an optical signal from the optical transmission path into an electrical signal;
A second data reproducing device (74) for reproducing an electric signal output from the second light receiver (72) at a frequency corresponding to the second data rate;
A second discriminating device (80) for discriminating whether the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the first data rate or the second data rate;
When the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the first data rate, duplicate data is removed from the reproduced data by the second data reproducing device (74). Deduplication device (82)
The optical transmission system according to any one of claims 1 to 5 , further comprising: The second user optical terminator is
A second light receiver (72) for converting an optical signal from the optical transmission path into an electrical signal;
A second discriminating device (80) for discriminating whether the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the first data rate or the second data rate;
When the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the first data rate, the electrical signal output from the second light receiver (72) is the first data rate. When the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the second data rate, the second light receiver (72 light according to any one of claims 1 to 5, characterized by comprising a second data reproducing apparatus for reproducing an electric signal output from the frequency corresponding to the second data rate from) Transmission system. The first user optical terminator (18-1) corresponding to the first data rate and the second user optical terminator (18-2, 18) corresponding to the second data rate faster than the first data rate. A plurality of user-side optical terminators including 18-2a);
A center-side optical termination device (10 , 10a) connected to the plurality of user-side optical termination devices via an optical transmission line (12, 14, 16-1 , 16-2) , wherein the first user light Data to be transmitted to the terminating device (18-1) is output to the optical transmission line at the first data rate, and data to be transmitted to the second user optical terminating device (18-2, 18-2a). In the optical transmission system comprising: a center-side optical terminator that outputs to the optical transmission line at the second data rate ,
The center-side optical termination device outputting unicast data to the first user optical termination device (18-1) to the optical transmission line at the first data rate;
The center-side optical termination device outputting multicast or broadcast data including the first user optical termination device (18-1) to the optical transmission line at the first data rate;
The center-side optical terminal device outputs unicast data to the second user optical terminal device (18-2, 18-2a) to the optical transmission line at the second data rate.
An optical transmission method comprising : The center side optical terminator is
Send the data in a frame configuration consisting of a preamble, a payload that contains the data, and an interframe gap,
The preamble of a rate corresponding to the first data rate for both the first user optical terminator (18-1) and the second user optical terminator (18-2, 18-2a). Occur and
Outputting a payload including data to be transmitted to the first user optical terminal device (18-1) at a rate corresponding to the first data rate;
Outputting a payload including data to be transmitted to the second user optical termination device (18-2, 18-2a) at a rate corresponding to the second data rate. 9. The optical transmission method according to 8 . The center side optical terminator is
An optical signal input from the user optical termination device (18-1, 18-2a) via an optical transmission line is converted into an electrical signal,
Reproducing the electrical signal at a frequency corresponding to the first data rate;
Determining whether the data rate of the data from the user optical terminal device (18-1, 18-2a) is the first or second data rate;
When the data rate of the data from the user optical terminal device (18-1, 18-2a) is the second data rate, duplicate data is removed from the data reproduced at the first data rate. The optical transmission method according to claim 8 or 9 , wherein: The second user optical terminator is
An optical signal from the optical transmission line is converted into a second electrical signal;
Reproducing the second electrical signal at a frequency corresponding to the second data rate;
Determining whether the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the first or second data rate;
When the data rate of the data transmitted from the center-side optical terminal device (10, 10a) is the second data rate, duplicate data is reproduced from the data reproduced at a frequency corresponding to the second data rate. 10. The optical transmission method according to claim 8, wherein the optical transmission method is removed. The first user optical terminator (18-1) corresponding to the first data rate and the second user optical terminator (18-2, 18) corresponding to the second data rate faster than the first data rate. 18-2a) is connected to a plurality of user-side optical terminators via an optical transmission line, and transmits / receives data,
Preamble of a rate corresponding to the first data rate for both the first user optical terminal device (18-1) and the second user optical terminal device (18-2, 18-2a). A preamble generator (46) for generating
A payload including data to be transmitted to the first user optical terminator (18-1) is output at a rate corresponding to the first data rate, and the second user optical terminator (18-2, 18) is output. -A) a payload generating device (38) for outputting a payload including data to be transmitted at a rate corresponding to the second data rate
An optical terminal device comprising: The payload generator apparatus, the optical terminal device according to claim 1 2, characterized in that it comprises a code length converter (38) for converting the code length of the data. Further, the first data for both the data to be transmitted to the first user optical termination device (18-1) and the second user optical termination device (18-2, 18-2a). optical terminal device according to claim 1 2 or 1 3, characterized in that it comprises an inter-frame gap generator (48) for generating an inter-frame gap corresponding rate to the rate. Furthermore,
A light receiver (56) for converting an optical signal input from the user optical terminal device (18-1, 18-2a) via an optical transmission line into an electrical signal;
A data reproduction device (60a) for reproducing an electrical signal output from the light receiver (56) at a frequency corresponding to the second data rate;
A first discriminating device (30a) for discriminating whether the data rate of data from the user optical terminal device (18-1, 18-2a) is the first data rate or the second data rate;
When the data rate of the data from the user optical terminal device (18-2a, 18-1) is the second data rate, duplicate data is removed from the reproduced data by the first data reproducing device (60a). Deduplication device (62a)
ONT according to any one of claims 1 2 to 1 4, characterized in that it comprises and.

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