JP2011041104A - Digital multiplex transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a digital multiplex transmission device capable of efficiently transmitting a client signal, according to the bit rate of the client signal. <P>SOLUTION: The digital multiplex transmission device 1 includes a clock converter 12 and storages 16-1 to 16-N. The clock converter 12 supplies a clock signal of a frequency according to the clock frequency of the client signal, using frequencies except for frequencies specified at OTN (ITU-T, G.709 Amendment3 (April, 2009) or G.Sup43 (December, 2008)). Each of the storages 16-1 to 16-N holds the client signal in a hold container, in synchronization with the clock signal supplied from the clock converter 12. Thus, the hold container suitable for the client signal can be used, and the client signal can be transmitted efficiently. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a digital multiplex transmission apparatus.

  The rapid increase in traffic accompanying the rapid spread of the Internet continues. The traffic is expected to increase further in the future due to the expansion of use from conventional voice and character-based communication to communication of high-definition still images and moving images, and an increase in the amount of communication data. In addition, communication standards have been diversified as communication data has increased. Conventionally, Ethernet (registered trademark) widely used in LAN (Local Area Network), Fiber Channel used in SAN (Storage Area Network), and video signal communication standard HD-SDI (High Definition). Various communication standards such as Serial Digital Interface are defined. Considering the diversification of applications provided on the network, it is expected that various communication standards will be defined in the future. In addition, the need for services that transfer signals of these various communication standards over a wide area via the backbone network will continue to increase.

  SDH (Synchronous Digital Hierarchy, see Non-patent Document 1) or the like as an international standard for a digital multiplex transmission system that enables such a wide-area transmission service of various signals and realizes a large-capacity, high-reliability, and economical backbone network. OTN (Optical Transport Network, see Non-Patent Document 2) is standardized by ITU-T (International Telecommunication Union Telecommunication Standardization Sector). These standards accommodate various signals, multiplex them and transmit them in large volumes, enabling economic wide-area transfer services, and adding control information to achieve highly reliable communications and errors. By adding a correction code, it has excellent features such as enabling further long-distance transmission. For this reason, a large number of transmission systems compliant with these standards have been introduced, and the number will continue to increase as communication traffic increases.

  When a digital multiplex transmission apparatus that receives a client signal and transmits it to the backbone network in this transmission system accommodates the client signal, it first adds an overhead including control / monitoring information to the client signal and accommodates it in the accommodating container. . Thereafter, the plurality of storage containers are time-division multiplexed into one transmission container and then transmitted. In this case, the multiplexing number may be 1, and the storage container and the transmission container may be the same. For example, in the case of OTN, a client signal of 9.953 gigabits / second is accommodated in an accommodation container ODU2 (Optical channel Data Unit 2) having a payload capacity of 9.995 gigabits / second, and four ODU2s have a payload capacity of 40.150. The data is multiplexed on the transmission container ODU3 of gigabit / second, and then an error correction code or the like is added to the transmission container and transmitted as OTU3 (Optical channel Transport Unit 3) having a bit rate of 43.018 gigabit / second.

  In the existing OTN, six fixed and discrete bit rates ODU0, ODU1, ODU2, ODU2e, ODU3, and ODU4 are defined as accommodating containers / transmission containers. ODU0 has a payload capacity of 1.239 gigabits / second, ODU1 has a payload capacity of 2.488 gigabits / second, ODU2 has a payload capacity of 9.995 gigabits / second, and ODU2e has a payload capacity of 10.356. ODU3 has a payload capacity of 40.151 gigabit / second, and ODU4 has a payload capacity of 104.356 gigabit / second. Similarly, SDH also defines a fixed and discrete bit rate. For example, the bit rate of STM-16 is 2.488 gigabit / second, the bit rate of STM-64 is 9.953 gigabit / second, and the bit rate of STM-256 is 39.813 gigabit / second.

FIG. 23 is a block diagram showing a schematic configuration of a conventional digital multiplex transmission apparatus.
In the figure, a digital multiplex transmission apparatus 9 includes a clock generator 91, clock converters 92 to 94, receivers 95-1 to 95-N (N is a positive integer), and storage units 96-1 to 96-N. And a multiplexing unit 97 and a transmission unit 98.
The clock generator 91 generates a clock signal having a constant frequency. When the clock signal is input from the clock generator 91, the clock converters 92 to 94 convert the frequency and output a clock signal having a frequency defined by an international standard of a digital multiplex transmission system. The clock signal output from the clock conversion unit 92 is input to the storage units 96-1 to 96-N. The clock signal output from the clock conversion unit 93 is input to the multiplexing unit 97. The clock signal output from the clock converter 94 is input to the transmitter 98.

The receiving units 95-1 to 95-N include a light receiving unit (not shown), an amplifying unit (not shown), and a clock & data recovery unit (not shown). The receiving units 95-1 to 95-N receive the client signal as an optical signal at the light receiving unit and convert it into an electrical signal. Next, the receiving units 95-1 to 95-N amplify the electric signal in the amplifying unit. Then, the receiving units 95-1 to 95 -N reproduce the clock signal from the amplified electrical signal in the clock & data recovery unit, and convert the electrical signal into a digital data signal.
The accommodation unit 96-i (i is a positive integer satisfying 1 ≦ i ≦ N) operates in synchronization with the clock signal from the clock conversion unit 92, and receives the client signal input from the reception unit 95-i as the payload of the accommodation container. In order to match the capacity, rate adaptation such as justification processing is performed, and overhead such as control information is added to generate a storage container that stores client signals. The bit rate of the receiving container corresponds to the clock frequency input from the clock conversion unit 92. Therefore, the storage unit 96-i generates a storage container having a bit rate defined by international standards and the like.

  The multiplexing unit 97 multiplexes one or a plurality of storage containers generated by the storage units 96-1 to 96 -N to the transmission container, and adds overhead such as control information as necessary. The multiplexing unit 97 performs multiplexing by assigning a plurality of containers to each part of the payload area of the transmission container. At this time, the bit rate of the transmission container corresponds to the clock frequency output from the clock converter 93. Therefore, the multiplexing unit 97 generates a transmission container having a bit rate defined by international standards. After that, the multiplexing unit 97 inputs the multiplexed signal to the transmission unit 98, and the transmission unit 98 adds an error correction code or the like to the input signal and transmits it.

FIG. 24 is a diagram illustrating a bit rate of a storage container and a transmission container generated by a conventional digital multiplex transmission apparatus.
When the reception units 95-1 to 95-N receive the client signal, the accommodation units 96-1 to 96-N generate accommodation containers having a bit rate defined in the OTN. Then, the multiplexing unit 97 multiplexes the accommodation containers generated by the accommodation units 96-1 to 96 -N, and generates a transmission container having a bit rate defined by OTN.

FIG. 25 shows a container, a transmission container, and a transmission signal that are generated when the digital multiplex transmission apparatus 9 receives four CBR10G signals (Constant Bit Rate signals, 9.95328 gigabits / second) as client signals. FIG.
For example, when the receiving units 95-1 to 95-4 receive the CBR10G signal, the accommodating units 96-1 to 96-4 each generate an ODU2 signal that accommodates the CBR10G signal. ODU2 is a container with a payload capacity of 9.995 gigabits / second. Then, the multiplexing unit 97 multiplexes these four ODU2 signals to generate an ODU3 signal. The ODU3 signal is a transmission container having a payload capacity of 40.151 gigabit / second. Thereafter, the transmission unit 98 generates and transmits an OTU3 signal obtained by adding an error correction code or the like to the ODU3 signal. The OTU3 signal is a signal having a bit rate of 43.018 gigabit / second.

"Network Node Interface for the synchronous digital hierarchy (SDH)", January 2007, ITU-T Recommendation G.707 / Y.1322 "Interfaces for the Optical Transport Network (OTN)", March 2003, ITU-T Recommendation G.709 / Y.1331 "Generic framing procedure (GFP)", August 2005, ITU-T G.7041 / Y.1303 "Interfaces for the optical transport network (OTN) Amendment 3", April 2009, ITU-T G709 / Y.1331 Amendment 3 "Transport of IEEE 10G BASE-R in Optical Transport Networks (OTN)", December 2008, ITU-T Series G Supplement 43

Several problems arise when attempting to transfer a diversified client signal over a wide area using a digital multiplex transmission system.
First, there are various bit rates of client signals due to diversification of client signals. On the other hand, the bit rate of the storage container and the transmission container specified in the existing digital multiplexing hierarchy, and the payload capacity determined by the bit rate and the structure of the storage container and the transmission container are as follows. As shown in FIG. 5, it is fixed and discrete. For this reason, when the client signal is accommodated in the digital multiplex transmission apparatus and multiplexed and transferred over a wide area, the bit rate of the client signal and the payload capacity of the accommodation container differ greatly depending on the client signal. In this case, when the bit rate of the client signal is smaller than the payload capacity of the storage container, the storage efficiency is deteriorated. In addition, when the bit rate of the client signal is larger than the payload capacity of the container, it cannot be accommodated, or it is necessary to perform signal processing such as code conversion on the client signal for accommodation. In order to perform this signal processing, it is necessary to perform processing lacking flexibility and consistency, such as defining an accommodation method specialized for each client signal.

  For example, there are 8G-FC, 10GbE-WAN-PHY, 10GbE-LAN-PHY, 10G-FC, and 16G-FC as client signals having a bit rate near 10 Gigabit / second. These bit rates are 8.5 Gigabit / second for 8G-FC, 9.95328 Gigabit / second for 10GbE-WAN-PHY, 10.3125 Gigabit / second for 10GbE-LAN-PHY, and 10.51875 for 10G-FC. Gigabit / second, 16G-FC is 17.0 Gigabit / second. On the other hand, the OTN storage container ODU2 has a payload capacity of 9.995 gigabits / second, and 8G-FC and 10GbE-WAN-PHY are bit rates that can be stored, but the 8G-FC bit rate and the ODU2 Due to the difference in payload capacity, a payload capacity of about 1.5 gigabits / second is wasted.

  Further, since 10 GbE-LAN-PHY, 10 G-FC, and 16 G-FC have a bit rate larger than the payload capacity of ODU 2, they cannot be accommodated in ODU 2 as they are. In order to accommodate these in ODU2, processing according to the client signal is performed. For example, in order to accommodate 10 GbE-LAN-PHY in ODU2, it is accommodated after the bit rate is reduced using framing technology GFP (see Generic Framing Procedure, Non-Patent Document 3). Also, in order to accommodate 10G-FC in ODU2, it is accommodated after the bit rate is reduced using transcoding (see Non-Patent Document 4). Thus, the conventional digital multiplex transmission apparatus requires processing for accommodating the client signal in the accommodating container. In addition, processing that is different depending on the client signal and lacks flexibility and consistency is required. In addition, the configuration of the apparatus becomes complicated to perform these processes. Further, the reduction of the bit rate deletes a part of the information held by the client signal, which causes a decrease in interconnectivity due to a decrease in transparency (transparency).

In addition, the spread of OTN is progressing and the implementation to the user's network equipment is also progressing, and the problems associated therewith are becoming obvious. In order to realize highly functional monitoring and control and highly reliable communication using error correction codes, routers or L2 switches are directly sending out OTN signals and the like. Generally, a client signal such as Ethernet (registered trademark) has a limited monitoring / control function compared to SDH, OTN, etc., and therefore, failure point confirmation and signal deterioration detection are not sufficiently performed. Therefore, by using SDH or OTN in a router or L2 switch, the reliability of a UNI (User-Network Interface) section can be improved.
When an OTN signal is used for a user's network device, the bit rate of the OTN signal that is a client signal may be larger than the payload capacity of the accommodating container of the digital multiplex transmission apparatus. In this case, when receiving the OTN signal as the client signal, the digital multiplex transmission device terminates the OTN signal to rewrite the overhead information in order to reduce the bit rate of the OTN signal, and then transmits it to the network of the communication carrier. To do. Therefore, it is necessary to negotiate in advance the overhead that may be used between the user and the communication carrier. If the user's network device arbitrarily uses the overhead portion of the client signal, the carrier system's transmission system may rewrite the overhead information of the client signal or may not be able to handle the client signal. Moreover, there is a possibility that the independence between the user's network device and the network of the communication carrier cannot be sufficiently maintained.

  As an example, when a user device sends out an OTU2 signal and transfers it over a wide area in the network of the communication carrier, the transmission device of the communication carrier receives the OTU2 signal and then performs a code correction process using an error correction code to perform OTU2 After terminating the signal, the ODU2 signal storing control information and the like is terminated, and after rewriting the overhead, the OTU2 signal is generated again and transmitted to the network of the communication carrier. The reason why such processing is necessary is that the client signal received from the user and the transmission signal of the network of the communication carrier have the same bit rate. For this reason, in order for a communication carrier to add some monitoring / control information for providing a highly reliable service, it is necessary to delete and add a part of the signal from the user. As a result, there is a problem of reduction in transparency when transferring a signal from the user. In addition, when the user equipment uses overhead uniquely or uses a unique code as an error correction code, there is a possibility of causing a problem in the interoperability between the user equipment and the equipment of the communication carrier. These problems arise because digital multiplex transmission systems such as SDH and OTN have only fixed and discrete payload capacity receiving and transmission containers.

  The present invention has been made in view of such circumstances, and an object of the present invention is to realize a digital transmission system that efficiently transmits a client signal in accordance with the bit rate of the client signal.

[1] The present invention has been made to solve the above-described problems. A digital multiplex transmission apparatus according to an aspect of the present invention includes a receiving unit that receives a client signal, and a first clock supply that supplies a clock signal. And a second clock supply unit, and a frame-structured signal defined in OTN from the client signal received by the reception unit, operating in synchronization with the clock signal supplied from the first clock supply unit The storage unit that generates the storage container is operated in synchronization with the clock signal supplied from the second clock supply unit, and the storage container generated by the storage unit is time-division multiplexed to be defined in the OTN. A multiplexing unit that generates a transmission container that is a frame-structured signal, and a transmission unit that transmits the time-division multiplexed signal. Locking the supply unit supplies a clock signal of a frequency other than the frequency defined in OTN, characterized in that.
Here, the multiplexing unit reads out a fixed number of bits of data alternately from each of the client signals to which the control signal is added, and sequentially inputs the data to the transmission unit, so that the client signal to which the control signal is added is timed. Divide and multiplex.
Since this digital multiplex transmission apparatus supplies a clock signal having a frequency other than the frequency specified by OTN, the digital multiplex transmission apparatus is more suitable for the bit rate of the client signal than when only the clock signal having the frequency specified by OTN is used. An appropriate clock signal can be used. The accommodating unit adds the control information to the client signal in synchronization with the clock signal, so that the client signal can be efficiently accommodated. In addition, it is not necessary to adjust the bit rate of the client signal by using a clock signal having a frequency higher than the bit rate of the client signal, and transparency is reduced by deleting a part of the client signal. Does not occur. In addition, since this digital multiplex transmission apparatus supplies a clock signal having a frequency other than the frequency specified by OTN, the bit rate of the multiplexed signal is higher than when only the clock signal having the frequency specified by OTN is used. A more appropriate clock signal according to the above can be used. By multiplexing the client signal to which the control information is added in synchronization with the clock signal, the multiplexing unit can efficiently multiplex and transmit the signal. Also, by using a clock signal corresponding to the sum of the bit rates of each signal to be multiplexed, it is possible to eliminate useless payload capacity and increase transmission efficiency. In addition, since the bit rate does not increase unnecessarily, electronic circuits and optical modules that operate at a low speed can be used as compared with the case where the bit rate is higher, and an increase in transmission distance can be expected.

[2] A digital multiplex transmission apparatus according to an aspect of the present invention is the above-described digital multiplex transmission apparatus, and the frequency defined in the OTN is 1.244 GHz, 2.499 GHz, or 10. It is characterized by being 037 gigahertz, 10.400 gigahertz, 40.319 gigahertz, 41.774 gigahertz, 41.786 gigahertz or 104.794 gigahertz.
This digital multiplex transmission device is defined in OTN (ITU-T, G.709Amendment 3 (April 2009) or G. Sup43 (December 2008)), 1.244 GHz, 2.499 GHz, or Since a clock signal other than 10.037 GHz, 10.400 GHz, 40.319 GHz, 41.774 GHz, 41.786 GHz, or 104.794 GHz is used, the above-described effect can be obtained.
[3] A digital multiplex transmission apparatus according to an aspect of the present invention is the digital multiplex transmission apparatus described above, wherein the reception unit restores a clock signal of the client signal, and the first clock supply unit is , Measure the frequency of the clock signal of the client signal, select a frequency other than the frequency specified in the OTN based on the measured frequency of the clock signal of the client signal, and supply the clock signal of the selected frequency The second clock supply unit supplies a clock signal having a frequency defined by OTN.
Since this digital multiplex transmission apparatus selects a frequency other than the frequency defined in the OTN based on the clock signal of the client signal and supplies the clock signal of the selected frequency, the clock signal corresponding to the client signal is used. Can do. The accommodation unit can efficiently accommodate the client signal by adding control information to the client signal in synchronization with the clock signal. In addition, it is not necessary to adjust the bit rate of the client signal by using a clock signal having a frequency higher than the bit rate of the client signal, and transparency is reduced by deleting a part of the client signal. Does not occur.

[4] A digital multiplex transmission apparatus according to an aspect of the present invention is the digital multiplex transmission apparatus described above, wherein the reception unit restores a clock signal of the client signal, and the first clock supply unit is , Measure the frequency of the clock signal of the client signal, select a frequency other than the frequency specified in the OTN based on the measured frequency of the clock signal of the client signal, and supply the clock signal of the selected frequency The second clock supply unit calculates a sum of bit rates of the client signal to which the control information is added, and based on the calculated sum of the bit rates, a frequency other than the frequency specified in the OTN is calculated. Selecting and supplying a clock signal of the selected frequency.
Since this digital multiplex transmission apparatus selects a frequency other than the frequency defined in the OTN based on the clock signal of the client signal and supplies the clock signal of the selected frequency, the clock signal corresponding to the client signal is used. Can do. The accommodation unit can efficiently accommodate the client signal by adding control information to the client signal in synchronization with the clock signal. In addition, it is not necessary to adjust the bit rate of the client signal by using a clock signal having a frequency higher than the bit rate of the client signal, and transparency is reduced by deleting a part of the client signal. Does not occur. In addition, this digital transmission device selects a frequency other than the frequency defined in the OTN based on the sum of the bit rates of the client signal to which the control information is added, and supplies a clock signal of the selected frequency. A clock signal corresponding to the sum of bit rates can be used. By multiplexing the client signal to which the control information is added in synchronization with the clock signal, the multiplexing unit can efficiently multiplex and transmit the signal. Also, by using a clock signal corresponding to the sum of the bit rates of each signal to be multiplexed, it is possible to eliminate useless payload capacity and increase transmission efficiency. In addition, since the bit rate does not increase unnecessarily, electronic circuits and optical modules that operate at a low speed can be used as compared with the case where the bit rate is higher, and an increase in transmission distance can be expected.

[5] A digital multiplex transmission device according to an aspect of the present invention is the above-described digital multiplex transmission device, wherein the first clock supply unit supplies a clock signal having a frequency defined by OTN, The second clock supply unit calculates the sum of the bit rates of the client signal to which the control information is added, and selects a frequency other than the frequency prescribed in the OTN based on the calculated sum of the bit rates. Supplying a clock signal of the selected frequency.
This digital transmission apparatus selects a frequency other than the frequency defined in the OTN based on the sum of the bit rates of the client signal to which control information is added, and supplies a clock signal of the selected frequency. A clock signal corresponding to the sum of the two can be used. By multiplexing the client signal to which the control information is added in synchronization with the clock signal, the multiplexing unit can efficiently multiplex and transmit the signal. Also, by using a clock signal corresponding to the sum of the bit rates of each signal to be multiplexed, it is possible to eliminate useless payload capacity and increase transmission efficiency. In addition, since the bit rate does not increase unnecessarily, electronic circuits and optical modules that operate at a low speed can be used as compared with the case where the bit rate is higher, and an increase in transmission distance can be expected.

[6] A digital multiplex transmission apparatus according to an aspect of the present invention is the digital multiplex transmission apparatus described above, wherein the first or second clock supply unit includes a clock generation unit that generates a clock signal; The receiving unit selects a frequency based on the clock signal recovered from the client signal or the sum of the bit rates of the client signals to which control information is added, which is input to the multiplexing unit, and the clock generating unit generates And a clock converter for supplying a clock signal obtained by frequency-converting the clock signal to the selected frequency.
This digital multiplex transmission apparatus uses a clock generation unit and a clock conversion unit to supply a clock signal having a frequency corresponding to the frequency of the client signal or the sum of the bit rates of the respective signals to be frequency-multiplexed. Signals can be accommodated and multiplexed for transmission.

[7] A digital multiplex transmission apparatus according to an aspect of the present invention is the digital multiplex transmission apparatus described above, in which the clock conversion unit generates clock signals generated by the clock generation unit at different frequencies. Based on a sum of bit rates of a plurality of individual clock conversion units to be converted and the clock signal restored from the client signal, or a client signal to which control information is added, input to the multiplexing unit A clock selection unit that selects any one of the clock signals frequency-converted by the clock conversion unit, and the digital multiplex transmission apparatus selects any one of the clock signals having a plurality of frequencies. Use a clock signal with a frequency corresponding to each of multiple client signals with different bit rates for efficiency. In addition, client signals can be accommodated, and signals can be efficiently multiplexed and transmitted using a clock signal having a frequency corresponding to the sum of the bit rates of the signals to be frequency multiplexed.

[8] A digital multiplex transmission apparatus according to an aspect of the present invention is the above-described digital multiplex transmission apparatus, wherein the clock conversion unit includes a frequency synthesizer.
In this digital multiplex transmission apparatus, the frequency of the clock signal is variable because the frequency of the clock signal is converted by a frequency synthesizer. Therefore, this digital multiplex transmission apparatus efficiently accommodates a client signal using a clock signal having a frequency corresponding to the bit rate of the client signal, and a clock having a frequency corresponding to the sum of the bit rates of the signals to be frequency multiplexed. The signals can be efficiently multiplexed and transmitted using the signals.

[9] A digital multiplex transmission apparatus according to an aspect of the present invention is the above-described digital multiplex transmission apparatus, wherein the first or second clock supply unit generates a plurality of clock signals having different frequencies. The clock generator generates the clock signal based on the sum of the bit rates of the clock signal restored from the client signal or the client signal with control information added to the multiplexer. The digital multiplex transmission device is characterized by comprising any one of the clock signals generated by the clock generation unit, so that any one of the clock signals is selected. A clock signal having a frequency corresponding to each of a plurality of client signals having different bit rates is efficiently used. The signal can be efficiently multiplexed and transmitted using a clock signal having a frequency corresponding to the sum of the bit rates of the signals to be frequency-multiplexed.

[10] A digital multiplex transmission apparatus according to an aspect of the present invention is the digital multiplex transmission apparatus described above, further including a third clock supply unit that supplies a clock signal to the transmission unit, and the transmission unit Transmits the time-division multiplexed signal with an error correction code added thereto, and the third clock supply unit measures the frequency of the clock signal supplied to the multiplexing unit and adds the error to the measured frequency. A frequency obtained by multiplying the redundancy of the correction code is calculated, and a clock signal having a frequency equal to or higher than the calculated frequency is supplied.
By adding the above error correction code, the bit rate of the signal to be transmitted becomes higher by the redundancy than the bit rate of the multiplexed signal. Therefore, this digital multiplex transmission apparatus transmits a multiplexed signal by transmitting it using a clock signal having a frequency that is higher by the redundancy of the error correction code than the frequency of the clock signal used when multiplexing the client signal. Can be transmitted efficiently.

  According to the present invention, the client signal can be efficiently transmitted according to the bit rate of the client signal.

It is a figure which shows the frame structure prescribed | regulated to OTN. It is a block diagram which shows schematic structure of the digital multiplex transmission apparatus in the 1st Embodiment of this invention. It is a block diagram which shows schematic structure of the clock converter 12 in the embodiment. It is a block diagram which shows another schematic structure of the clock converter 12 in the embodiment. It is a data block diagram which shows the data structure of the accommodation container in the embodiment. It is a data block diagram which shows the data structure of the transmission container in the embodiment. In the same embodiment, it is a figure which shows the bit rate of the accommodation container and transmission container which the digital multiplex transmission apparatus 1 produces | generates. 5 is a flowchart showing a processing procedure in which a storage unit 16-i generates a storage container and inputs it to a multiplexing unit 17 in the same embodiment. 4 is a flowchart illustrating a processing procedure in which a multiplexing unit 17 generates a transmission container and inputs it to a transmission unit 18 in the embodiment. FIG. 4 is a diagram illustrating a first example of a client signal received by the digital multiplex transmission apparatus 1, a storage container used by the digital multiplex transmission apparatus 1, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 1 in the embodiment. . FIG. 6 is a diagram illustrating a second example of a client signal received by the digital multiplex transmission apparatus 1, a storage container used by the digital multiplex transmission apparatus 1, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 1 in the embodiment. . FIG. 10 is a diagram illustrating a third example of a client signal received by the digital multiplex transmission apparatus 1, a storage container used by the digital multiplex transmission apparatus 6, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 1 in the embodiment. . FIG. 2 is a configuration diagram showing a schematic configuration of a digital multiplex transmission apparatus 8 that receives a transmission signal transmitted by the digital multiplex transmission apparatus 1 in the embodiment. It is a block diagram which shows schematic structure of the digital multiplex transmission apparatus 2 in the 1st modification of the embodiment. It is a block diagram which shows schematic structure of the digital multiplex transmission apparatus 3 in the 2nd modification of the embodiment. It is a block diagram which shows schematic structure of the digital multiplex transmission apparatus 4 in the 2nd Embodiment of this invention. In the same embodiment, it is a figure which shows the bit rate of the accommodation container and transmission container which the digital multiplex transmission apparatus 4 produces | generates. FIG. 4 is a diagram illustrating a first example of a client signal received by the digital multiplex transmission apparatus 4, a storage container used by the digital multiplex transmission apparatus 4, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 4 in the embodiment. . FIG. 6 is a diagram illustrating a second example of a client signal received by the digital multiplex transmission device 4, a storage container used by the digital multiplex transmission device 4, a transmission container, and a transmission signal transmitted by the digital multiplex transmission device 4 in the embodiment. . It is a block diagram which shows schematic structure of the digital multiplex transmission apparatus 5 in the 3rd Embodiment of this invention. In the same embodiment, it is a figure which shows the bit rate of the accommodation container and transmission container which the digital multiplex transmission apparatus 5 produces | generates. FIG. 4 is a diagram illustrating an example of a client signal received by the digital multiplex transmission apparatus 5, a storage container used by the digital multiplex transmission apparatus 5, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 5 in the embodiment. It is a block diagram which shows schematic structure of the conventional digital multiplex transmission apparatus. It is a figure which shows the bit rate of the accommodation container and transmission container which the conventional digital multiplex transmission apparatus produces | generates. It is a figure which shows the accommodation container, transmission container, and transmission signal which are produced | generated when the conventional digital multiplex transmission apparatus receives four CBR10G signals as a client signal.

<First Embodiment>
The first embodiment of the present invention will be described below with reference to the drawings.
Upon receiving a client signal, which is a signal to be transmitted, the digital multiplex transmission apparatus 1 of the present embodiment adds an overhead such as a control signal to generate an accommodation container having a frame structure defined in the OTN. The added client signal is multiplexed to generate a transmission container having a frame structure defined by OTN and transmitted to the carrier network (backbone). The same applies to digital multiplex transmission apparatuses 2 to 5 described later.

Here, a frame structure defined in OTN will be described with reference to FIG.
This figure shows a frame structure defined in OTN.
As shown in the figure, the frame structure defined in the OTN includes an overhead (OH) region R11, a payload region R12, and an error correction code region R13. The overhead area R11 includes an FAS (Frame Alignment Signal) area R111, an OTU-OH area R112, an ODU-OH area R113, and an OPU-OH area R114. In addition, 1 row × 1 column in the figure corresponds to 1-byte data.
The FAS area R111 is an area for a frame synchronization pattern, and indicates the start position of the frame. The OTU-OH region R112 includes information for section monitoring. The ODU-OH area R113 includes information for path monitoring. The OPU-OH area includes a method indicating the type of client signal and the method for accommodating the client signal.
The payload area R12 is an area for accommodating client signals or multiplexed accommodation containers. The error correction code region R13 includes an error correction code. Note that the error correction code area may have a size different from that shown in FIG. When no error correction code is added, a value other than the error correction code, such as a fixed value “0”, may be included in the error correction code area.

FIG. 2 is a block diagram showing a schematic configuration of the digital multiplex transmission apparatus according to the first embodiment of the present invention. In the figure, a digital multiplex transmission apparatus 1 includes a clock generation unit 11, clock conversion units 12 to 14, reception units 15-1 to 15-N (N is a positive integer), and accommodation units 16-1 to 16-N. And a multiplexing unit 17 and a transmission unit 18. The clock generator 11 and the clock converter 12 correspond to the non-specified frequency clock supply unit of the present invention. Further, the clock generation unit 11 and the clock conversion unit 13 and the clock generation unit 11 and the clock conversion unit 14 correspond to the specified frequency clock supply unit of the present invention.
The clock generator 11 generates a clock signal having a constant frequency. When a clock signal is input from the clock generation unit 11, the clock conversion unit 12 converts the input clock signal into an OTN (ITU-T, G.709Amendment 3 (April 2009), which is an international standard for a digital multiplex transmission system. ) Or G. Sup43 (December 2008)) is converted to a clock signal having a frequency other than that defined in G. Sup43 (December 2008). Specifically, the clock conversion unit 12 converts the clock signal input from the clock generation unit 11 to 1.244 GHz, 2.499 GHz, 10.037 GHz, 10.400 GHz, or 40.319. It is converted into a clock signal having a frequency other than gigahertz, 41.774 gigahertz, 41.786 gigahertz, or 104.794 gigahertz.

  When the clock signal is input from the clock generator 11, the clock converters 13 and 14 convert the input clock signal into an OTN (ITU-T, G.709Amendment 3 (2009), which is an international standard for a digital multiplex transmission system. April) or G. Sup43 (December 2008)). Specifically, the clock conversion unit 13 converts the clock signal input from the clock generation unit 11 to 1.244 GHz, 2.499 GHz, 10.037 GHz, 10.400 GHz, 40.319. It is converted into a clock signal having a frequency of either gigahertz, 41.774 gigahertz, 41.786 gigahertz or 104.794 gigahertz. The clock conversion unit 14 converts the clock signal input from the clock generation unit 11 to 2.666 GHz, 10.709 GHz, 11.0996 GHz, 43.018 GHz, 44.571 GHz, 44. It is converted into a clock signal having a frequency of either 583 GHz or 111.810 GHz.

The clock conversion units 12, 13, and 14 include a combination of a frequency divider (not shown) and a multiplier (not shown). The clock conversion unit 12 inputs the converted clock signal to the storage units 16-1 to 16-N. The clock conversion unit 13 inputs the converted clock signal to the multiplexing unit 17. The clock converter 14 inputs the converted clock signal to the transmitter 18.
The receiving units 15-1 to 15-N include a light receiving unit (not shown), an amplifying unit (not shown), and a clock & data recovery unit (not shown). The receiving units 15-1 to 15-N receive the client signal as an optical signal at the light receiving unit and convert it into an electrical signal. Next, the receiving units 15-1 to 15-N amplify this electric signal in the amplifying unit. The receiving units 15-1 to 15-N reproduce (recover) the clock signal from the amplified electrical signal in the clock & data recovery unit, and convert the electrical signal into a digital data signal.

  The accommodating unit 16-i (i is a positive integer satisfying 1 ≦ i ≦ N) operates in synchronization with the clock signal from the clock converting unit 12, and receives the client signal input from the receiving unit 15-i as a payload of the accommodating container. In order to match the capacity, rate adaptation such as justification processing is performed. Next, the storage unit 16-i adds an overhead such as control information to generate a storage container that stores the client signal. The bit rate of the container corresponds to the frequency of the clock signal input from the clock conversion unit 12. Accordingly, the storage unit 16-i generates a storage container having a bit rate different from the bit rate defined by the international standard.

The multiplexing unit 17 time-division-multiplexes one or a plurality of storage containers generated by the storage units 16-1 to 16-N into a transmission container, and adds overhead such as control information as necessary. The multiplexing unit 17 alternately reads data of a predetermined number of bits from a plurality of accommodating containers, sequentially assigns the data to a part of the payload area of the transmission container, and inputs the data to the transmission unit 18 to perform time division multiplexing.
At this time, the bit rate and payload capacity of the transmission container correspond to the frequency of the clock signal input from the clock converter 13. Therefore, the multiplexing unit 17 generates a transmission container having a bit rate defined by international standards. Thereafter, the multiplexing unit 17 inputs the multiplexed signal to the transmission unit 18, and the transmission unit 18 generates a transmission signal by adding an error correction code or the like to the input signal, and transmits the transmission signal to the carrier network. At this time, the bit rate of the transmission signal corresponds to the frequency of the clock signal input from the clock converter 14. Therefore, since the transmission unit 18 transmits a transmission signal having a bit rate defined by an international standard or the like, an inexpensive optical transmission / reception module distributed in the market can be used. Thereby, the digital multiplex transmission apparatus 1 can be manufactured economically.

FIG. 3 is a configuration diagram showing a schematic configuration of the clock converter 12.
In the figure, the clock conversion unit 12 includes a clock conversion unit (individual clock conversion unit) 121-1 to 121-M (M is a positive integer) and a clock selection unit 122.
The clock converters 121-1 to 121-M frequency-convert the clock signals input from the clock generator 11 at a predetermined ratio, for example, to generate clock signals at intervals of 1 megahertz. When the clock signal of the client signal is input from the receiving unit 15-i (i is a positive integer of 1 ≦ i ≦ N), the clock selection unit 122 measures the frequency of the input clock signal. The clock selection unit 122 is a clock signal having a frequency of 239/238 times or more of the clock frequency of the client signal among the clock signals input from the clock conversion units 121-1 to 121 -M, and the client signal The one closest to 239/238 times the clock frequency is selected. Here, the reason why the clock frequency of the client signal is multiplied by 239/238 is to secure a bit rate for adding overhead such as control information to the client signal. The clock selection unit 122 inputs the selected clock signal to the accommodation unit 16-i corresponding to the reception unit 15-i.

With this configuration, the clock conversion unit 12 inputs a clock signal having a frequency suitable for the client signal to the accommodating units 16-1 to 16-N with respect to a plurality of types of client signals. 16-1 to 16-N can accommodate a client signal in a container having a bit rate suitable for the client signal. In particular, even when the receiving units 15-1 to 15-N simultaneously receive different types of client signals, the receiving units 16-1 to 16-N send the client signals to the receiving containers having the bit rates suitable for the client signals. Accommodate.
When a client signal having the same clock signal is input to the receiving units 15-1 to 15-N, the clock selection unit 122 may select only one clock signal. In this case, a clock signal is input to the clock selection unit 122 from one receiving unit such as the receiving unit 15-1. The clock selection unit 122 selects any one of the clock signals input from the clock conversion units 121-1 to 121-M, and inputs the selected clock signal to the storage units 16-1 to 16-N. Thus, since the clock selection unit 122 does not need to select a plurality of clock signals, the circuit scale can be reduced.
The frequency of the clock signal output from the clock converter 12 may include a specified frequency. Thereby, the digital multiplex transmission apparatus 1 can perform processing more suitable for the received client signal by using a container having a larger bit rate.
The receiving units 15-1 to 15-N read out information indicating the type of the client signal from the client signal and input it to the clock selecting unit 122, and the clock selecting unit 122 selects the clock signal based on this information. You may do it. When the clock selection unit 122 selects a clock signal having a frequency corresponding to the type of the client signal, a clock signal having a frequency suitable for the client signal can be input to the accommodating units 16-1 to 16-N.

The configuration of the clock converter 12 that outputs a plurality of frequencies is not limited to that shown in FIG.
FIG. 4 is a configuration diagram showing another schematic configuration of the clock converter 12.
In the figure, the clock converter 12 includes frequency synthesizers 126-1 to 126-N.
The frequency synthesizer 126-i (i is a natural number satisfying 1 ≦ i ≦ N) converts the frequency of the clock signal input from the clock generator 11 into one of continuous frequencies. When the clock signal of the client signal is input from the receiving unit 15-i, the frequency of the input clock signal is measured. The frequency synthesizer 126-i converts the clock signal input from the clock generator 11 to a frequency 239/238 times the clock frequency of the client signal, and outputs the converted clock signal.
By adopting such a configuration, the same effect as in the case of FIG. 3 can be obtained.
When the receiving units 15-1 to 15-N receive only client signals having the same clock frequency, the digital multiplex transmission apparatus 1 is different from the clock generating unit 11 in place of the clock converting unit 12. The clock generator may be provided. In this case, the clock generator supplies a clock signal having a constant frequency corresponding to the clock frequency of the client signal. The same applies to the clock converters 13 and 14.

FIG. 5 is a data configuration diagram showing the data configuration of the storage container.
FIG. 4A is a data configuration diagram of a storage container including stuff bytes. In FIG. 9A, a client signal T21 is a client signal accommodated in the accommodation container. The container T22 includes a part T221 and T223 of the client signal T21, a stuff byte T222, and an overhead T224. The portions T221 and T223 of the client signal T21 together correspond to the client signal T21. The stuff byte T222 is a byte for adjusting the bit rate when the bit rate of the client signal T21 is smaller than the payload capacity of the accommodating container. The accommodating units 16-1 to 16-N insert a bit value “0” as a stuff byte. Overhead T224 includes control information.
FIG. 5B is a data configuration diagram of a storage container that does not include stuff bytes. In FIG. 2B, a client signal T23 is a client signal accommodated in the accommodation container. The container T24 includes a client signal T241 and an overhead T242. The client signal T241 corresponds to the client signal T23. The overhead T242 includes control information in the same manner as the overhead T224 in FIG.

  When the bit rate of the client signal is smaller than the payload capacity of the storage container, the storage units 16-1 to 16-N generate a storage container including stuff bytes as shown in FIG. The accommodating units 16-1 to 16-N include the information on the staff positions in the overhead. On the other hand, when the bit rate of the client signal T21 is the same as the payload capacity of the accommodating container, it is not necessary to adjust the bit rate, so that stuff bytes are unnecessary. In this case, the storage units 16-1 to 16-N generate storage containers that do not include stuff bytes as shown in FIG.

FIG. 6 is a data configuration diagram showing the data configuration of the transmission container.
The storage containers T31 to T33 in the figure are storage containers that are time-division multiplexed and stored in the transmission container. The transmission container T34 includes a payload area T341 and an overhead T342. The payload area T341 includes storage containers T31 to T33 that are time-division multiplexed. The overhead includes control information.

Next, the operation of the digital multiplex transmission apparatus 1 will be described.
FIG. 7 is a diagram illustrating a bit rate of a storage container and a transmission container generated by the digital multiplex transmission apparatus 1.
When the reception units 15-1 to 15-N receive the client signal, the accommodation units 16-1 to 16-N generate accommodation containers having a bit rate other than the bit rate defined in the OTN. Then, the multiplexing unit 17 multiplexes the accommodation containers generated by the accommodation units 16-1 to 16-N, and generates a transmission container having a bit rate defined by OTN. Thereafter, the transmission unit 18 generates a transmission signal by attaching an error correction code or the like to the transmission container, and transmits the generated transmission signal to the provider network.

FIG. 8 is a flowchart illustrating a processing procedure in which the storage unit 16-i generates a storage container and inputs it to the multiplexing unit 17.
The accommodating section 16-i starts this processing when the digital multiplex transmission apparatus 1 is activated.
In step S <b> 1, the accommodating unit 16-i determines whether or not a client signal is input from the receiving unit 15-i. If it is determined that it has been input (step S1: YES), the process proceeds to step S2, and if it is determined that it has not been input (step S1: NO), the process returns to step S1.
In step S2, the accommodating unit 16-i performs rate adaptation. Rate adaptation is a process of matching the bit rate of the client signal with the payload capacity of the accommodating container. For example, the accommodating unit 16-i performs a justification process for inserting a stuff byte when the bit rate of the client signal is smaller than the payload capacity of the accommodating container.
In step S3, the accommodation unit 16-i generates an accommodation container by adding overhead to the client signal subjected to rate adaptation.
In step S <b> 4, the storage unit 16-i inputs the generated storage container to the multiplexing unit 17. Then, it returns to step S1.

FIG. 9 is a flowchart illustrating a processing procedure in which the multiplexing unit 17 generates a transmission container and inputs it to the transmission unit 18.
The multiplexer 17 starts this process when the digital multiplex transmission apparatus is activated.
In step S <b> 21, the multiplexing unit 17 determines whether a storage container is input from the storage units 16-1 to 16 -N. If it is determined that it has been input (step S21: YES), the process proceeds to step S22. If it is determined that it has not been input (step S21: NO), the process returns to step S21.
In step S <b> 22, the multiplexing unit 17 performs time-division multiplexing of the storage containers received from the storage units 16-1 to 16 -N.
In step S23, the multiplexing unit 17 generates a transmission container by adding overhead to the time-division multiplexed container.
In step S <b> 24, the multiplexing unit 17 inputs the generated transmission container to the transmission unit 18. Then, it returns to step S21.

FIG. 10 is a diagram illustrating a first example of a client signal received by the digital multiplex transmission apparatus 1, a storage container used by the digital multiplex transmission apparatus 1, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 1.
In the figure and the following figures, a container or transmission container having a payload capacity of B bits / second is indicated by “ODU [B]”. A transmission signal having a bit rate of B bits / second is indicated by “OTU [B]”.
In the figure, the receiving unit 15-1 receives a client signal 10GbE having a clock frequency of 10.31 gigabits / second. The receiving unit 15-2 and the receiving unit 15-4 receive the client signal 8GFC having a clock frequency of 8.50 gigabit / second. The receiving unit 15-3 receives the client signal STM-64 having a clock frequency of 9.95 gigabits / second.

As described above, the clock selection unit 122 of the clock conversion unit 12 selects a clock signal for each of the accommodation units 16-1 to 16-N, and inputs the selected clock signal to the accommodation units 16-1 to 16-N. . The clock conversion unit 12 selects a frequency from, for example, 1.0 GHz increments, and inputs a 11.0 GHz clock signal to the housing unit 16-1. In this case, 239/238 times the clock frequency of the client signal is 10.31 × 239/238 = 10.43 (gigahertz). Therefore, the clock signal of 11.0 GHz is the clock signal that is equal to or greater than 10.43 GHz and closest to 10.43 GHz.
Similarly, the clock conversion unit 12 inputs a 9.0 gigahertz clock signal to the accommodation units 16-2 and 16-4, and inputs a 10.0 gigahertz clock signal to the accommodation unit 16-3.

The accommodating part 16-1 accommodates the client signal having the clock frequency of 10.31 gigabit / second input from the receiving part 15-1 in the accommodating container having the payload capacity of 11.0 gigabit / second. The accommodating units 16-2 and 16-4 receive the client signal having a clock frequency of 8.50 gigabit / second and the payload capacity of 9.0 gigabit / second respectively input from the receiving units 15-2 and 15-4. Store in a storage container. The accommodating unit 16-3 accommodates the client signal having the clock frequency of 9.95 gigabit / second input from the receiving unit 15-3 in the accommodating container having the payload capacity of 10.0 gigabit / second. These storage containers are storage containers having a bit rate different from the bit rate defined in international standards.
As described above, the clock converter 12 selects a clock signal having a frequency higher than and close to the frequency obtained by adding the overhead frequency to the clock frequency of the client signal.
Note that the clock converter 12 may select the clock signal from a frequency having a granularity other than 1.0 gigahertz, or may select the clock signal from a continuous frequency.

The multiplexing unit 17 multiplexes the transmission containers input from the accommodation units 16-1 to 16-N and accommodates them in the transmission container ODU3.
Here, when the multiplexing unit 17 multiplexes the storage container, it is necessary that the sum of the bit rates of the storage container is equal to or less than the payload capacity of the transmission container. In FIG. 10, the sum of the bit rates of the storage containers is (11.0 + 9.0 + 10.0 + 9.0) × 239/238 = 39.2 (gigabits / second). On the other hand, the payload capacity of the transmission container ODU3 is 40.2 gigabits / second, which satisfies the above conditions. Therefore, the multiplexing unit 17 can multiplex these accommodation containers and accommodate them in the transmission container ODU3. Note that 239/238 is the value of the bit rate of the storage container with respect to the payload capacity of the storage container. The bit rate of the container is the payload capacity plus overhead capacity. Therefore, when the receiving container is stored in the transmission container, the sum of the bit rates of the receiving container needs to be less than the payload capacity of the transmission container.
Note that the multiplexing unit 17 performs stuffing processing for adjusting the bit rate and justification processing for absorbing frequency deviations as necessary when the storage containers are multiplexed and stored in the transmission container.
Note that the number of client signals received by the digital multiplex transmission apparatus 1 may be other than four.

Note that a part of the storage units 16-1 to 16-N may use a storage container having a bit rate defined by international standards or the like.
FIG. 11 is a diagram illustrating a second example of a client signal received by the digital multiplex transmission apparatus 1, a storage container used by the digital multiplex transmission apparatus 1 and a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 1. This figure is different from FIG. 10 in that the accommodating unit 16-3 accommodates the client signal in the accommodating container ODU2.
Here, the bit rate of the storage container ODU2 is 10.0 gigabit / second (10.037 gigabit / second), and the sum of the bit rates of the storage container is 39.2 gigabit / second as in the case of FIG. . Therefore, as in the case of FIG. 10, the multiplexing unit 17 can multiplex these accommodation containers and accommodate them in the transmission container ODU3.

FIG. 12 is a diagram illustrating a third example of a client signal received by the digital multiplex transmission apparatus 1, a storage container used by the digital multiplex transmission apparatus 1, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 1.
In the figure, receiving units 15-1 and 15-2 receive a client signal OTU2 having a clock frequency of 10.71 gigabits / second. The receiving units 15-3 and 15-4 receive the client signal 8GFC having a clock frequency of 8.50 gigabit / second.
The accommodating units 16-1 and 16-2 receive client signals having a clock frequency of 10.71 gigabits / second and payload capacities of 11.0 gigabits / second respectively input from the receiving units 15-1 and 15-2. Store in a storage container. The accommodating units 16-3 and 16-4 receive the client signal having a clock frequency of 8.50 gigabit / second and the payload capacity of 9.0 gigabit / second respectively input from the receiving units 15-3 and 15-4. Store in a storage container.
These storage containers are storage containers having a bit rate different from the bit rate defined in international standards.

The multiplexing unit 17 multiplexes the transmission containers input from the accommodating units 16-1 to 16-N and accommodates them in the transmission container ODU3. The transmission unit 18 generates the transmission signal OTU3 from the transmission container input from the multiplexing unit 17 and transmits it.
Since the digital multiplex transmission apparatus 1 accommodates the client signal OTU2 in a container having a payload capacity larger than the bit rate of the client signal, the client signal is not changed in bit value or arrangement (that is, bit transparent). Can be accommodated. In addition, by using an accommodation container having a bit rate different from the bit rate defined in the international standard or the like, the accommodation efficiency can be accommodated without deteriorating.

  For example, when the client signal OTU2 having a bit rate of 10.71 gigabit / second is accommodated in the accommodating container ODU2 having a payload capacity of 9.995 gigabit / second, the bit rate of the client signal is larger than the payload capacity of the accommodating container. Therefore, for example, it is necessary to terminate the client signal OTU2 and perform processing for adjusting the bit rate for the client signal. For this reason, the client signal cannot be accommodated in a bit transparent manner. On the other hand, since the digital multiplex transmission apparatus 1 accommodates the client signal in a bit transparent manner as described above, the overhead of the client signal is transmitted as it is on the network of the communication carrier. This improves the transparency of the client signal. In addition, the user's communication device and the digital multiplex transmission device 1 can freely use signal overhead, respectively, and can maintain the independence of the user's network and the communication carrier's network.

FIG. 13 is a configuration diagram illustrating a schematic configuration of a digital multiplex transmission apparatus 8 that receives a transmission signal transmitted by the digital multiplex transmission apparatus 1.
In the figure, the digital multiplex transmission apparatus 8 includes a clock converters 82 to 84, a receiver 85, a separator 86, a restoring unit 87-1 to 87-N (N is a positive integer), and a transmitter 88-1 to 88-. N is comprised.
The receiving unit 85 receives a transmission signal from the digital multiplex transmission apparatus 1, reproduces a clock signal from the received transmission signal, and converts the received transmission signal into a digital data signal.
When the clock signal is input from the receiver 85, the clock converter 82 is defined in accordance with the clock frequency of the clock converter 13 of the digital multiplex transmission apparatus 1 in the international standard of the digital multiplex transmission system. Convert to frequency clock signal. The clock converter 82 performs this frequency conversion by performing frequency conversion at a predetermined ratio.

When the clock signal is input from the receiver 85, the clock converter 83 converts the clock signal into a clock signal having a frequency corresponding to the clock frequency of the clock converter 12 of the digital multiplex transmission apparatus 1. The clock conversion unit 83 performs this frequency conversion by performing frequency conversion at a predetermined ratio. Note that the digital multiplex transmission apparatus 1 transmits the overhead of the transmission container including the information on the clock frequency of each container, the reception unit 85 or the separation unit 86 reads this information, and according to the information read by the clock conversion unit 83 The clock signal may be converted to a different frequency.
When the clock signal is input from the receiver 85, the clock converter 84 converts the clock signal to the same frequency as the clock frequency of the client signal received by the digital multiplex transmission apparatus 1. The same frequency as the clock frequency of the client signal is a frequency that is not defined by the international standard of the digital multiplex transmission system. The clock converter 84 performs this frequency conversion by performing frequency conversion at a predetermined ratio. The clock conversion unit 84 may convert the clock signal to a frequency corresponding to the frequency of the clock signal output from the clock conversion unit 83.
The clock conversion unit 82 inputs the converted clock signal to the separation unit 86. The clock conversion unit 83 inputs the converted clock signal to the restoration units 87-1 to 87-N. The clock conversion unit 84 inputs the converted clock signal to the transmission units 88-1 to 88 -N.

The separation unit 86 reads out each container signal from the signal input from the reception unit 85 and inputs it to the restoration units 87-1 to 87-N.
The restoration unit 87-i (i is a positive integer satisfying 1 ≦ i ≦ N) reads the client signal from the storage container input from the reception unit 85 and inputs the client signal to the transmission unit 88-i.
The transmission unit 88-i transmits the client signal input from the restoration unit 87-i.
As described above, the digital multiplex transmission apparatus 8 restores and transmits the client signal received by the digital multiplex transmission apparatus 1.

  As described above, in the digital multiplex transmission apparatus 1, the clock conversion unit 12 inputs a clock signal having a frequency not defined by the international standard or the like to the accommodation units 16-1 to 16 -N. Therefore, the clock conversion unit 12 can convert the clock signal to a frequency suitable for the client signal instead of a discrete frequency such as a frequency defined by OTN, for example. As a result, the accommodation units 16-1 to 16-N can use an accommodation container having a payload capacity suitable for the client signal, and it is not necessary to include a large capacity stuff byte in the accommodation container. . For example, an accommodation container having a payload capacity of 4 gigabits / second can be used for a client signal having a bit rate of 4 gigabits per second. For a client signal with a bit rate of 15 gigabits / second, an accommodation container having a payload capacity of 15 gigabits / second can be used.

  In the prior art, for example, when 2.5 gigabit / second, 10 gigabit / second, and 40 gigabit / second are defined as the payload capacity of the container, for a client signal with a bit rate of 4 gigabit / second, Since the 2.5-Gigabit / second container is too small, use the 10-Gigabit / second container or reduce the bit rate by processing such as code conversion to make the 2.5-Gigabit / second container. Had to house. That is, in the prior art, the accommodation efficiency of client signal accommodation was low or additional signal processing was required, whereas the digital multiplex transmission apparatus 1 has a large degree of freedom in the payload capacity of the accommodation container, and the additional signal The client signal can be directly accommodated with high accommodation efficiency without processing.

On the other hand, the multiplexing unit 17 uses a bit rate transmission container defined by international standards and the like. The multiplexing unit 17 multiplexes a single container or a plurality of storage containers in this transmission container. For example, the multiplexing unit 17 has a bit rate of 10 gigabit / second, 16 gigabit / second, 16 gigabit / second, and 9 gigabit / second in a transmission container having a payload capacity defined by OTN of 40 gigabit / second, respectively. Four containment containers are multiplexed.
The sum of the bit rates of this container is (10 + 5 + 16 + 9 = 40) and does not exceed 40 gigabits. Therefore, the multiplexing unit 17 multiplexes these containers and accommodates them in a transmission container having a payload capacity of 40 gigabits / second. can do.
In this way, efficient multiplexing can be performed by the multiplexing unit 17 combining and multiplexing a plurality of types of storage containers.

Note that the storage units 16-1 to 16-N may use one storage container among the storage containers having a continuous payload capacity, or a storage container having a payload capacity of discrete but fine granularity. One storage container may be used. The storage units 16-1 to 16-N use a storage container having a payload capacity corresponding to the frequency of the clock signal input from the clock conversion unit 12.
For example, for a client signal having a bit rate of 5.123 gigabit / second, a receiving container having a payload capacity of 5.123 gigabit / second may be used, or 0.1 gigabit in 0.1 gigabit / second units. A receiving container having a payload capacity of 5.2 gigabits / second may be selected from the receiving containers having a payload capacity of a granularity of / sec. Furthermore, a payload capacity with a margin may be used in consideration of the clock deviation of the bit rate of the client signal. For example, an accommodation container having a payload capacity of 5.3 gigabit / second is used for a client signal having a bit rate of 5.123 gigabit / second.

(First modification)
Next, a digital multiplex transmission apparatus 2 that is a first modification of the digital multiplex transmission apparatus 1 in the present embodiment will be described.
In the digital multiplex transmission apparatus 1, the clock converter 12 converts the frequency of the clock signal input from the clock generator 11. On the other hand, in the digital multiplex transmission apparatus 2, the clock converters 22-1 to 22-N (N is a positive integer and the number of receivers) are received by the receivers 25-1 to 25-N. The frequency of the clock signal to be reproduced from is converted.
FIG. 14 is a configuration diagram showing a schematic configuration of the digital multiplex transmission apparatus 2.
In the figure, the digital multiplex transmission apparatus 2 includes a clock generating unit 11, clock converting units 22-1 to 22-N and 13 and 14, receiving units 25-1 to 25-N, and accommodating units 16-1 to 16-. N, a multiplexing unit 17 and a transmission unit 18 are included.
In the figure, the same reference numerals (11, 13, 14, 16-1 to 16-N, 17, 18) are assigned to portions corresponding to the respective portions in FIG.

The receiving unit 25-i (i is a positive integer satisfying 1 ≦ i ≦ N) is similar to the receiving unit 15-i of FIG. 2 in that the light receiving unit (not shown), the amplifying unit (not shown), and the clock & data recovery unit ( The optical signal is received and converted into an electric signal, the electric signal is amplified, the clock signal is reproduced from the amplified electric signal, and the electric signal is converted into a digital data signal. To do. The receiving unit 25-i is different from the receiving unit 15-i in FIG. 2 in that the reproduced clock signal is input to the clock converting unit 22-i.
When the clock signal is input from the receiver 25-i, the clock converter 22-i converts the input clock signal into a clock signal having a non-specified frequency. The clock conversion unit 22-i inputs the converted clock signal to the accommodation unit 16-i.

  In this way, since the digital multiplex transmission apparatus 2 inputs the clock signal regenerated from the client signal to the accommodating units 16-1 to 16-N, the accommodating units 16-1 to 16-N have bits corresponding to the client signal. Containment containers can be generated at rates. As a result, the bit rate of the client signal and the payload capacity of the receiving container become the same or synchronized, so that the client signal can be accommodated by bit synchronous mapping or fixed stuff byte insertion, and there is no need to perform rate adaptation.

(Second modification)
Next, a digital multiplex transmission apparatus 3 that is a second modification of the digital multiplex transmission apparatus 1 in the present embodiment will be described.
In the digital multiplex transmission apparatus 2, the clock conversion unit 13 converts the frequency of the clock signal input from the clock generation unit 11 and supplies a clock signal with a specified ratio. On the other hand, in the digital multiplex transmission apparatus 3, the receiving units 25-1 to 25-N select one of the clock signals restored from the client signal and perform frequency conversion at a predetermined ratio, thereby generating a clock signal with a specified frequency. Can do. In the digital multiplex transmission apparatus 3, the clock converter 33 converts the frequency of the clock signal that the receiver 25-1 reproduces from the client signal.

FIG. 15 is a configuration diagram showing a schematic configuration of the digital multiplex transmission apparatus 3.
In the figure, the digital multiplex transmission apparatus 3 includes a clock generator 11, clock converters 22-1 to 22-N and 33 and 14, receivers 25-1 to 25-N, and receivers 16-1 to 16-N. And a multiplexing unit 17 and a transmission unit 18.
In the figure, the same reference numerals (11, 222-1 to 22-N, 14, 25-1 to 25-N, 16-1 to 16-N, 17, 18) are assigned to the portions corresponding to the respective portions in FIG. The description is omitted.
When the clock signal is input from the receiving unit 25-1, the clock conversion unit 33 converts the input clock signal into a clock signal having a specified frequency.

In this way, the clock converter 33 converts the frequency of the clock signal input from the receiver 25-1 and inputs the same clock signal as that of the clock converter 13 of FIG. Can generate a transmission container as in the case of the digital multiplex transmission apparatus 1.
The clock conversion unit that converts the frequency of the clock signal reproduced from the client signal is not limited to that of the digital multiplex transmission device 2 or the digital multiplex transmission device 3 described above, and the clock conversion units 22-1 to 22-N and 13 and All or a part of 14 may be used. For example, all the clock conversion units of the clock conversion units 22-1 to 22-N, 13 and 14 in FIG. 14 may perform frequency conversion on the clock signal reproduced from the client signal. Alternatively, the clock converters 13 and 14 may frequency-convert the clock signal reproduced from the client signal.
As shown in FIG. 15, when the clock signal supplied from the clock converter 33 to the multiplexer 17 and the clock signal supplied from the clock converter 14 to the transmitter 18 are asynchronous, the clock converter 14 has a higher frequency. The clock signal is output so that the multiplexed signal can be transmitted efficiently without omission.

<Second Embodiment>
FIG. 16 is a configuration diagram showing a schematic configuration of the digital multiplex transmission apparatus 4 in the second embodiment of the present invention.
In the figure, the digital multiplex transmission apparatus 4 includes a clock generator 11, clock converters 12, 43 and 44, receivers 15-1 to 15-N, storage units 16-1 to 16-N, and a multiplexer 47. And a transmission unit 48. The clock generation unit 11 and the clock conversion unit 12, the clock generation unit 11 and the clock conversion unit 43, and the clock generation unit 11 and the clock conversion unit 44 correspond to the non-specified frequency clock supply unit of the present invention.
In the figure, the same reference numerals (11, 12, 15-1 to 15-N, 16-1 to 16-N) are assigned to portions corresponding to the respective portions in FIG.
When the clock signal is input from the clock generator 11, the clock converters 43 and 44 convert the input clock signal into a clock signal with an unspecified frequency, as with the clock converter 12. Specifically, the clock conversion unit 43 converts the clock signal input from the clock generation unit 11 to 1.244 GHz, 2.499 GHz, 10.037 GHz, 10.400 GHz, or 40.319. It is converted into a clock signal having a frequency other than gigahertz, 41.774 gigahertz, 41.786 gigahertz, or 104.794 gigahertz. The clock conversion unit 44 converts the clock signal input from the clock generation unit 11 to 2.666 GHz, 10.709 GHz, 11.0996 GHz, 43.018 GHz, 44.571 GHz, or 44.571. It is converted into a clock signal having a frequency other than 583 GHz or 111.810 GHz.
The clock conversion unit 43 inputs the converted clock signal to the multiplexing unit 47. The clock conversion unit 44 inputs the converted clock signal to the transmission unit 48.

Similar to the multiplexing unit 17 in FIG. 2, the multiplexing unit 47 multiplexes one or more accommodation containers generated by the accommodation units 16-1 to 16-N into a transmission container, and also transmits control information and the like as necessary. Add overhead. The multiplexing unit 47 is different from the multiplexing unit 17 of FIG. 2 in that these processes are performed in synchronization with the clock signal of the non-specified frequency supplied from the clock conversion unit 43.
The transmission unit 48 generates a transmission signal by adding an error correction code or the like to the signal received from the multiplexing unit 47, and transmits the transmission signal to the operator network, similarly to the transmission unit 18 of FIG. The transmission unit 48 is different from the transmission unit 18 of FIG. 2 in that these processes are performed in synchronization with a clock signal of an unspecified frequency supplied from the clock conversion unit 44.

FIG. 17 is a diagram illustrating a bit rate of a storage container and a transmission container generated by the digital multiplex transmission apparatus 4.
When the reception units 15-1 to 15-N receive the client signal, the accommodation units 16-1 to 16-N generate accommodation containers having a bit rate other than the bit rate defined in the OTN. Then, the multiplexing unit 47 multiplexes the accommodation containers generated by the accommodation units 16-1 to 16-N, and generates a transmission container having a bit rate other than the bit rate defined in the OTN. Thereafter, the transmission unit 48 generates a transmission signal by attaching an error correction code or the like to the transmission container, and transmits the generated transmission signal to the operator network.
The multiplexing unit 47 uses a transmission container other than the discrete bit rate defined by the international standard by synchronizing with the clock signal of the non-specified frequency supplied from the clock conversion unit 43. As a result, when a single or a plurality of storage containers are multiplexed on a transmission container, a transmission container having a payload capacity suitable for the bit rate of the storage container can be used, and transmission efficiency does not decrease.
For example, the digital multiplex transmission device 4 uses one transmission container of 44 gigabits / second when transmitting four storage containers of 11 gigabit / seconds. The digital multiplex transmission device 4 uses one transmission container of 48 gigabit / second for transmission when four accommodation containers of 12 gigabit / second are transmitted.

FIG. 18 is a diagram illustrating a first example of a client signal received by the digital multiplex transmission apparatus 4, a storage container used by the digital multiplex transmission apparatus 4, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 4. Similarly to the clock conversion unit 12, the clock conversion units 43 and 44 each include a plurality of clock selection units and output clock signals having frequencies corresponding to the accommodation container and the transmission container.
In the figure, the receiving unit 15-1 and the receiving unit 15-4 receive a client signal 10GbE having a clock frequency of 10.31 gigabits / second. The receiving unit 15-2 receives a client signal 8GFC having a clock frequency of 8.50 gigabits / second. The receiving unit 15-3 receives the client signal 16GFC having a clock frequency of 17.00 gigabits / second.

Similarly to the case of FIG. 10, the storage units 16-1 to 16 -N operate in synchronization with the clock signal supplied from the clock conversion unit 12 and store the client signal in the storage container.
The accommodating units 16-1 and 16-4 respectively receive the client signal having a clock frequency of 10.31 gigabit / second and the payload capacity of 11.0 gigabit / second that are input from the receiving units 15-1 and 15-4, respectively. Store in a storage container. The accommodating part 16-2 accommodates the client signal having the clock frequency of 8.50 gigabit / second input from the receiving part 15-2 in the accommodating container having the payload capacity of 9.0 gigabit / second. The accommodating part 16-3 accommodates the client signal input from the receiving part 15-3 and having a clock frequency of 17.00 gigabit / second in an accommodating container having a payload capacity of 17.0 gigabit / second.
These storage containers are storage containers having a bit rate different from the bit rate defined in international standards.

The multiplexing unit 47 multiplexes the transmission containers input from the accommodation units 16-1 to 16-N and accommodates the transmission containers in a transmission container having a payload capacity of 49.0 gigabits / second.
As in the case of FIG. 10, the multiplexing unit 47 multiplexes accommodation containers and accommodates them in the transmission container, and justification for absorbing stuff processing for adjusting the bit rate and frequency deviation as necessary. Apply processing.
The transmission unit 48 adds an error correction code of 7% redundancy to the transmission container input from the multiplexing unit 47 and transmits it as a transmission signal of 52.5 gigabits / second. For this purpose, the clock conversion unit 44 stores in advance the redundancy of the error correction code added by the multiplexing unit 47. The clock converter 44 measures the frequency of the clock signal output from the clock converter 43 and calculates a frequency obtained by multiplying the measured frequency by the redundancy. The clock conversion unit 44 selects a clock signal having a frequency equal to or higher than the calculated frequency and closest to this frequency and supplies the selected clock signal to the transmission unit 48. The transmitter 48 adds an error correction code defined by OTN as an error correction code with 7% redundancy.
As described above, the clock conversion unit 44 supplies the clock signal according to the redundancy of the error correction code added by the transmission unit 48, so that the transmission unit 48 can transmit the signal of the transmission container efficiently. Can do.
The transmission unit 48 may add an error correction code other than that defined by OTN to the transmission container, or may add an error correction code with a redundancy other than 7%. Alternatively, the transmission unit 48 may not add an error correction code.

In the example of FIG. 18, the sum of the bit rates of the storage containers is (11.0 + 9.0 + 17.0 + 11.0) × 239/238 = 48.2 (gigabits / second). For this reason, the multiplexing unit 47 uses a transmission container having a payload capacity of 49.0 gigabits / second, instead of a transmission container having a payload capacity of 48.0 gigabits / second, among transmission containers having a granularity of 1 gigabit / second.
The transmission unit 48 transmits a transmission signal of 49.0 × 255/238 = 52.5 (gigabit / second) to which an error correction code with 7% redundancy is added.

Note that the client signal received by the digital multiplex transmission apparatus 4 may be a signal having a bit rate defined by OTN.
FIG. 19 is a diagram illustrating a second example of a client signal received by the digital multiplex transmission apparatus 4, a storage container used by the digital multiplex transmission apparatus 4, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 4.
In the figure, receiving units 15-1 to 15-N receive a client signal OTU2 having a clock frequency of 10.71 gigabits / second.
The accommodating units 16-1 to 16-N respectively receive client signals having a clock frequency of 10.71 gigabits / second and payload capacities of 11.0 gigabits / second, which are input from the receiving units 15-1 to 15-4, respectively. Store in a storage container.
These storage containers are storage containers having a bit rate different from the bit rate defined in international standards.

The multiplexing unit 47 multiplexes the transmission containers input from the accommodation units 16-1 to 16-N and accommodates the transmission containers in a transmission container having a payload capacity of 45.0 gigabits / second.
The transmission unit 48 adds a 7% redundancy error correction code to the transmission container input from the multiplexing unit 47 to generate and transmit a transmission signal having a bit rate of 48.2 gigabits / second.
Since the digital multiplex transmission apparatus 4 accommodates the client signal OTU2 in an accommodation container having a payload capacity larger than the bit rate of the client signal, the client signal can be accommodated in a bit transparent manner. In addition, by using an accommodation container having a bit rate different from the bit rate defined in the international standard or the like, the accommodation efficiency can be accommodated without deteriorating.
Thereby, the same effect as the case of FIG. 12 is acquired.

  As described above, the digital multiplex transmission apparatus 4 uses a transmission container other than the discrete bit rate defined by the international standard or the like using the clock signal of the non-specified frequency. Thereby, the transmission container of the payload capacity | capacitance according to the bit rate of the accommodation container can be used, and transmission efficiency does not fall.

<Third Embodiment>
FIG. 20 is a configuration diagram showing a schematic configuration of the digital multiplex transmission apparatus 5 in the third embodiment of the present invention.
In the figure, the digital multiplex transmission device 5 includes a clock generator 11, clock converters 52, 43 and 44, receivers 15-1 to 15-N, storage units 56-1 to 56-N, and a multiplexer 47. And a transmission unit 48. The clock generation unit 11 and the clock conversion unit 52 correspond to the specified frequency clock supply unit of the present invention. The clock generation unit 11 and the clock conversion unit 43 and the clock generation unit 11 and the clock conversion unit 44 correspond to the non-specified frequency clock supply unit of the present invention.
In the figure, the same reference numerals (11, 15-1 to 15-N) are assigned to portions corresponding to the respective portions in FIG. 2, and the description thereof is omitted.

When the clock signal is input from the clock generator 11, the clock converter 52 converts the input clock signal into a clock signal with a specified frequency. Specifically, the clock conversion unit 52 converts the clock signal input from the clock generation unit 11 to 1.244 GHz, 2.499 GHz, 10.037 GHz, 10.400 GHz, or 40.319. It is converted into a clock signal having a frequency of either gigahertz, 41.774 gigahertz, 41.786 gigahertz or 104.794 gigahertz.
On the other hand, when the clock signal is input from the clock generator 11, the clock converters 43 and 44 convert the input clock signal into a clock signal having an unspecified frequency. The clock conversion unit 52 inputs the converted clock signal to the accommodation units 56-1 to 56-N. The clock conversion unit 43 inputs the converted clock signal to the multiplexing unit 47. The clock conversion unit 44 inputs the converted clock signal to the transmission unit 48.

The accommodation unit 56-i (i is a positive integer satisfying 1 ≦ i ≦ N) performs rate adaptation on the client signal input from the reception unit 15-i and adds overhead in the same manner as the accommodation unit 16-i in FIG. Then, a storage container is generated, and the generated storage container is input to the multiplexing unit 47. The housing unit 56-i is different from the housing unit 16-i of FIG. 2 in that these processes are performed in synchronization with a clock signal having a specified frequency supplied from the clock conversion unit 52.
Similar to the multiplexing unit 17 in FIG. 2, the multiplexing unit 47 multiplexes one or more accommodation containers generated by the accommodation units 56-1 to 56-N into a transmission container, and also transmits control information and the like as necessary. Add overhead. The multiplexing unit 47 is different from the multiplexing unit 17 of FIG. 2 in that these processes are performed in synchronization with the clock signal of the non-specified frequency supplied from the clock conversion unit 43.
The transmission unit 48 generates a transmission signal by adding an error correction code or the like to the signal received from the multiplexing unit 47, and transmits the transmission signal to the operator network, similarly to the transmission unit 18 of FIG. The transmission unit 48 is different from the transmission unit 18 of FIG. 2 in that these processes are performed in synchronization with a clock signal of an unspecified frequency supplied from the clock conversion unit 44.

FIG. 21 is a diagram illustrating a bit rate of a storage container and a transmission container generated by the digital multiplex transmission apparatus 5.
When the reception units 15-1 to 15-N receive the client signal, the storage units 56-1 to 56-N generate a storage container having a bit rate defined by OTN. The multiplexing unit 47 multiplexes the accommodation containers generated by the accommodation units 56-1 to 56-N, and generates a transmission container having a bit rate other than the bit rate defined in the OTN. Thereafter, the transmission unit 48 generates a transmission signal by attaching an error correction code or the like to the transmission container, and transmits the generated transmission signal to the operator network.

FIG. 22 is a diagram illustrating an example of a client signal received by the digital multiplex transmission apparatus 5, a storage container used by the digital multiplex transmission apparatus 5, a transmission container, and a transmission signal transmitted by the digital multiplex transmission apparatus 5.
In the figure, the receiving unit 15-1 and the receiving unit 15-2 receive a client signal STM-64 having a clock frequency of 9.95 gigabit / second. The receiving unit 15-3 receives the client signal STM-16 having a clock frequency of 2.49 gigabits / second.
The clock converter 52 inputs a clock signal with a specified frequency to the accommodating units 56-1 to 56-N, and the clock converters 43 and 44 input a clock signal with a non-specified frequency to the multiplexer 47 and the transmitter 48, respectively.
The accommodating units 56-1 and 56-2 accommodate the client signals input from the receiving units 15-1 and 15-2, respectively, in the accommodating container ODU2. The accommodation unit 56-3 accommodates the client signal input from the reception unit 15-3 in the accommodation container ODU1.
These storage containers are storage containers having a bit rate defined by international standards.
The multiplexing unit 47 multiplexes the storage containers input from the storage units 56-1 to 56-N, and stores them in a transmission container having a payload capacity of 23.0 gigabits. The transmission unit 48 adds a 7% redundancy error correction code to the transmission container input from the multiplexing unit 47 and transmits a transmission signal of 24.6 gigabits / second.

  In this way, the multiplexing unit 47 generates a transmission container having a bit rate other than the discrete bit rate specified in the OTN. A transmission container with an appropriate bit rate can be generated according to the container. As a result, the digital multiplex transmission device 5 multiplexes only the accommodation container to be transmitted and accommodates it in the transmission container. Therefore, regardless of the number of receiving containers to be transmitted, the transmission efficiency is improved as compared with a conventional digital multiplex transmission apparatus that multiplexes a specified number of receiving containers with a specified bit rate. That is, when there is no specified number of storage containers, the conventional digital multiplex transmission apparatus combines the empty storage containers into a specified number of storage containers, and multiplexes and transmits them. On the other hand, in the digital multiplex transmission apparatus 5, the transmission bit rate is reduced as compared with the conventional digital multiplex transmission apparatus without matching empty accommodation containers.

For example, in the case of FIG. 22 described above, the sum of the bit rates of the storage containers is (10.04 + 10.04 + 2.50) × 239/238 = 22.27 (gigabit / second). Therefore, in the conventional digital multiplex transmission apparatus, these accommodation containers are multiplexed into the transmission container ODU3 having a payload capacity of 40.150 gigabit / second. On the other hand, since the digital multiplex transmission device 5 multiplexes these accommodating containers into a transmission container having a payload capacity of 23.0 gigabits, it is possible to eliminate useless payload capacity. In addition, for example, when transmitting three containers of 10 gigabit / second, the conventional digital multiplex transmission apparatus transmits by one transmission container of 40 gigabit / second. At that time, the payload capacity for 10 gigabits / second becomes empty. On the other hand, the digital multiplex transmission apparatus 5 transmits with one transmission container of 30 gigabits / second. Thereby, useless payload capacity can be eliminated. Further, an electronic circuit or an optical transmission / reception module that operates at a speed lower than 40 gigabits / second can be used for the digital multiplex transmission device 5. In addition, the transmission distance can be extended by reducing the bit rate.
In addition, when transferring 5 accommodation containers of 10 gigabit / second, the conventional digital multiplex transmission apparatus transmits by 2 transmission containers of 40 gigabit / second. On the other hand, the digital multiplex transmission apparatus 5 transmits with one transmission container of 50 gigabits / second higher than the prescribed bit rate. In this way, by transmitting with one transmission container, the number of signals to be transmitted can be reduced and client signals can be transmitted efficiently. Here, the optical transmission module (not shown) of the transmission unit 48 has an operation range corresponding to a transmission rate of 50 gigabits / second.

  The embodiment of the present invention has been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and includes design changes and the like within a scope not departing from the gist of the present invention.

  The present invention is suitable for use in a digital multiplex transmission apparatus.

1, 2, 3, 4, 5, 8 Digital multiplex transmission apparatus 11 Clock generator 12, 13, 14, 222-1 to 33, 43, 44, 52, 82, 83, 84 Clock converter 15-1 ˜N, 25-1 to N, 85 receiving unit 16-1 to N, 56-1 to N accommodating unit 17, 47 multiplexing unit 18, 48, 88-1 to N transmitting unit 86 separating unit 87-1 to N reconstruction Part

Claims (10)

A receiver for receiving a client signal;
A first clock supply unit and a second clock supply unit for supplying a clock signal;
A receiving unit that operates in synchronization with a clock signal supplied from the first clock supply unit and that generates a receiving container that is a frame-structured signal defined in OTN from the client signal received by the receiving unit; ,
Operates in synchronization with the clock signal supplied from the second clock supply unit, and generates a transmission container that is a frame-structured signal defined in OTN by time-division multiplexing the storage container generated by the storage unit A multiplexing unit,
A transmitter for transmitting the time-division multiplexed signal;
Comprising
The first or second clock supply unit supplies a clock signal having a frequency other than the frequency defined in the OTN.
A digital multiplex transmission apparatus.   The frequency defined in the OTN is 1.244 GHz, 2.499 GHz, 10.037 GHz, 10.400 GHz, 40.319 GHz, 41.774 GHz, 41.786 GHz, or 104.794 GHz, The digital multiplex transmission apparatus according to claim 1. The receiver restores the clock signal of the client signal;
The first clock supply unit measures the frequency of the clock signal of the client signal, and selects and selects a frequency other than the frequency defined in the OTN based on the measured frequency of the clock signal of the client signal. Providing a clock signal of said frequency;
The second clock supply unit supplies a clock signal having a frequency defined in OTN.
The digital multiplex transmission apparatus according to claim 1 or 2, characterized by the above. The receiver restores the clock signal of the client signal;
The first clock supply unit measures the frequency of the clock signal of the client signal, and selects and selects a frequency other than the frequency defined in the OTN based on the measured frequency of the clock signal of the client signal. Providing a clock signal of said frequency;
The second clock supply unit calculates a sum of bit rates of the client signal to which the control information is added, and selects a frequency other than a frequency prescribed in the OTN based on the calculated sum of the bit rates. And supplying a clock signal of the selected frequency,
The digital multiplex transmission apparatus according to claim 1 or 2, characterized by the above. The first clock supply unit supplies a clock signal having a frequency defined by OTN,
The second clock supply unit calculates a sum of bit rates of the client signal to which the control information is added, and selects a frequency other than a frequency prescribed in the OTN based on the calculated sum of the bit rates. And supplying a clock signal of the selected frequency,
The digital multiplex transmission apparatus according to claim 1 or 2, characterized by the above. The first or second clock supply unit is
A clock generator for generating a clock signal;
The receiving unit selects a frequency based on a clock signal restored from the client signal, or a sum of bit rates of client signals to which control information is added, input to the multiplexing unit, and the clock generating unit generates A clock converter for supplying a clock signal obtained by frequency-converting the clock signal to the selected frequency;
The digital multiplex transmission apparatus according to claim 1, further comprising: The clock converter is
A plurality of individual clock converters for frequency-converting the clock signals generated by the clock generator to different frequencies;
The clock signal restored from the client signal, or the clock signal that has been frequency-converted by the individual clock conversion unit based on the sum of the bit rates of the client signal to which control information is added and that is input to the multiplexing unit A clock selection unit for selecting one of
The digital multiplex transmission apparatus according to claim 6, further comprising:   The digital multiplex transmission apparatus according to claim 6, wherein the clock conversion unit includes a frequency synthesizer. The first or second clock supply unit is
A plurality of clock generators for generating clock signals of different frequencies;
The clock signal generated by the clock generator based on the clock signal recovered from the client signal or the sum of the bit rates of the client signals to which control information is added and input to the multiplexing unit. A clock selection section for selecting one of them;
The digital multiplex transmission apparatus according to claim 1, further comprising: A third clock supply unit for supplying a clock signal to the transmission unit;
The transmitter transmits an error correction code to the time-division multiplexed signal,
The third clock supply unit measures the frequency of the clock signal supplied to the multiplexing unit, calculates a frequency obtained by multiplying the measured frequency by the redundancy of the error correction code, and is equal to or higher than the calculated frequency. Supply clock signal of frequency,
10. The digital multiplex transmission apparatus according to claim 1, wherein

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