JP2009218959A - Synchronous multiplexed transmission apparatus, synchronous multiplex transmission method, and synchronous multiplexed transmission program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To decrease delay of data in a transmission path. <P>SOLUTION: FIFO111a, b temporarily retain terminal data a, b. Read-out control parts 112a and 112b read the terminal data out of the FIFO111a and 111b at such reading timing determined by a timing determination part 122. A multiplexed information storing part 121 stores in advance the multiplexed information that specifies temporal order and the like when multiplexing the terminal data a, b. The timing determination part 122 determines a reading timing based on an apparatus clock and multiplexed information. An ACM part 123 controls a selector part 124, so that any one of the terminal data a, b read out by the reading control parts 112a and 112b is caused to be output from the selector part 124. The selector part 124 arranges the terminal data a, b within a single frame while switching them, with the acquired multiplexed data being output. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a synchronous multiplexing transmission apparatus, a synchronous multiplexing transmission method, and a synchronous multiplexing transmission program, and in particular, a synchronous multiplexing transmission apparatus, a synchronous multiplexing transmission method, and the like that can reduce data delay in a transmission path, And a synchronous multiplexing transmission program.

  In recent years, as a high-speed digital communication method using an optical fiber, for example, a communication method in accordance with an international standard such as SONET / SDH (Synchronous Optical NETwork / Synchronous Digital Hierarchy) has attracted attention. In these communication systems, data is transmitted from a terminal device via an optical fiber, and this data is transmitted to a destination terminal device while being subjected to cross-connect processing by a relay device that connects a plurality of optical fibers.

  In the cross-connect process in the relay device, data transmitted from different terminal devices is generally multiplexed. At this time, in the relay device, the time position of the data is adjusted by the time switch and then multiplexed by the space switch.

  For example, Patent Document 1 discloses a multiplexing device using a double buffer type time switch. FIG. 10 is a block diagram illustrating a configuration of the multiplexing device disclosed in Patent Document 1. In FIG. As shown in the figure, the multiplexing device includes a plurality of memory switches 10a and 10b, a switching timing generation circuit 20, a pattern identification circuit 30, an address generation circuit 40, and a selection control circuit 50.

  In such a multiplexing apparatus, input data is input to one of the memory switches 10a and 10b and held in one buffer for writing out of two buffers constituting the memory switch. When the write buffer is switched to the read buffer at the timing generated by the switching timing generation circuit 20, the data held in the buffer in the order specified by the address generation circuit 40 is sent to the selection control circuit 50. Is output.

  As described above, since writing and reading of data for one frame are performed at different timings by the memory switches 10a and 10b configured by double buffers, these memory switches 10a and 10b function as time switches. It is possible to freely adjust the temporal position of data within the frame. Then, the selection control circuit 50 sequentially selects one of the data output from the memory switches 10a and 10b to become output data. That is, the selection control circuit 50 functions as a space switch and multiplexes data output from the memory switches 10a and 10b.

JP-A-6-85777

  However, in a relay device compliant with a communication method such as SONET / SDH, when the time position of data is adjusted using a time switch, there is a problem that data delay increases. Specifically, in the case of the time switch using the double buffer described above, since data for one frame is written to the buffer and then the data is read from the buffer in the next frame, a delay occurs for at least one frame. Will do. In particular, when the data written in the buffer first is read from the buffer last by adjusting the temporal position, this data is delayed by two frames.

  In a communication method using an optical fiber, a plurality of relay devices are generally installed between a data transmission source terminal device and a data transmission destination terminal device. If a delay of one frame or more always occurs during the cross-connect process, the accumulated delay time cannot be ignored.

  Further, each relay device operates at a unique clock frequency, generates frame timing from each clock, and captures data one frame at a time in the relay device, but a frame of data transmitted by an optical fiber or the like. Since the beginning of the timing does not always coincide with the beginning of the frame timing in the relay apparatus, when data is input to the relay apparatus, a transmission delay of a time corresponding to a maximum of one frame occurs. Transmission delay also occurs when data is output from the relay device. If many relay devices are arranged on the transmission path, a very large delay occurs as a whole.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a synchronous multiplexing transmission device, a synchronous multiplexing transmission method, and a synchronous multiplexing transmission program that can reduce data delay in a transmission line. And

  In order to solve the above problems, a synchronous multiplexing transmission apparatus according to the present invention multiplexes a plurality of terminal data in a frame, holding means for separately holding a plurality of terminal data transmitted from different terminals. And adjusting means for adjusting the timing at which each terminal data is output from the holding means based on the data arrangement in the frame defined in advance, and outputting from the holding means at the timing adjusted by the adjusting means A configuration having multiplexing means for multiplexing terminal data is adopted.

  According to this configuration, since the separately held terminal data is output and multiplexed at each adjusted timing, there is no need to adjust the temporal position by writing the terminal data to the buffer and then reading it, The output terminal data can be immediately multiplexed as it is. In other words, terminal data is multiplexed without passing through a time switch in which a delay occurs due to writing to and reading from the buffer, and data delay in the transmission path can be reduced.

  In the synchronous multiplexing transmission apparatus according to the present invention, in the above configuration, the adjustment unit is determined by a determination unit that determines a write timing for writing each of the plurality of terminal data in the holding unit, and the determination unit Write control means for writing the plurality of terminal data to the holding means at a write timing, and the multiplexing means holds the data for a predetermined minimum holding time after being written by the write control means. The terminal data output after being taken is multiplexed simultaneously with the output.

  According to this configuration, since the terminal data written at the write timing is output after being held for the minimum holding time and multiplexed at the same time as the output, the terminal is adjusted without using a time switch by adjusting the write timing. It is possible to multiplex by adjusting the temporal position of data. Further, for example, the time for which the terminal data is held in the FIFO can be minimized.

  Further, the synchronous multiplexing transmission apparatus according to the present invention employs a configuration in which, in the above configuration, the write control unit transmits each of the plurality of terminal data from the terminal in accordance with the write timing determined by the determination unit. .

  According to this configuration, since the terminal data is transmitted from the terminal in accordance with the write timing, it is possible to reduce the time that the terminal data stays in the synchronous multiplexing transmission apparatus, and to reduce the delay in the entire synchronous multiplexing transmission apparatus. .

  In the synchronous multiplexing transmission apparatus according to the present invention, in the above configuration, the adjustment unit is determined by a determination unit that determines a read timing for reading each of the plurality of terminal data from the holding unit, and the determination unit Read control means for reading the plurality of terminal data from the holding means at a read timing, and the multiplexing means adopts a configuration for multiplexing the terminal data read by the read control means simultaneously with reading.

  According to this configuration, since the terminal data read at the read timing is multiplexed at the same time as the read, the time position of the terminal data can be adjusted without using the time switch by adjusting the read timing. Can be multiplexed.

  Further, the synchronous multiplexing transmission apparatus according to the present invention further includes a determination unit that determines whether or not it is necessary to change a temporal position of data constituting each terminal data in the above configuration, and the adjustment unit includes: As a result of the determination by the determination means, a configuration is adopted in which the timing output from the holding means is adjusted only for terminal data that does not require replacement.

  According to this configuration, since only terminal data that does not require replacement of the temporal position of the data is output at the adjusted timing, terminal data that requires replacement of the temporal position of the data is separately stored. The order can be changed and the required multiplexing can be performed reliably.

  In addition, the synchronous multiplexing transmission apparatus according to the present invention further includes a replacement unit that replaces a temporal position of data constituting the terminal data that needs to be replaced as a result of the determination by the determination unit, and the multiplexing unit includes: The terminal data output from the holding means at the timing adjusted by the adjusting means and the terminal data obtained by exchanging the temporal positions of the data by the replacing means are employed.

  According to this configuration, since the terminal data output at the adjusted timing and the terminal data subjected to the replacement of the temporal position of the data are multiplexed, the terminal data that does not need to be replaced in the data order In addition to preventing a delay associated with the replacement, the terminal data that needs to be replaced in order of data can be multiplexed in the required data order.

  Further, the synchronous multiplexing transmission method according to the present invention is a synchronous multiplexing transmission method in a synchronous multiplexing transmission apparatus provided with holding means for separately holding a plurality of terminal data transmitted from different terminals, An adjustment step for adjusting the timing at which each terminal data is output from the holding means, based on the data arrangement in the frame specified when multiplexing the terminal data in the frame, and the adjustment step And a multiplexing step for multiplexing terminal data output from the holding means at the determined timing.

  A synchronous multiplexing transmission program according to the present invention is a synchronous multiplexing transmission program executed by a computer having holding means for separately holding a plurality of terminal data transmitted from different terminals. An adjustment step for adjusting the timing at which each terminal data is output from the holding means based on a data arrangement in a frame defined in advance when the plurality of terminal data are multiplexed in a frame; and the adjustment step And a multiplexing step for multiplexing the terminal data output from the holding means at the timing adjusted in step (b).

  According to these, since the separately held terminal data is output and multiplexed at the adjusted timing, it is not necessary to adjust the temporal position by writing the terminal data into the buffer and then reading it, and the output The received terminal data can be immediately multiplexed as it is. In other words, terminal data is multiplexed without passing through a time switch in which a delay occurs due to writing to and reading from the buffer, and data delay in the transmission path can be reduced.

  According to the synchronous multiplexing transmission apparatus, the synchronous multiplexing transmission method, and the synchronous multiplexing transmission program disclosed in this specification, it is possible to reduce the data delay in the transmission path.

  The gist of the present invention is to control the timing at which data is output from a terminal interface provided corresponding to each of a plurality of terminals, and adjust the temporal position of the data without using a time switch. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 is a block diagram showing a schematic configuration of a transmission system according to Embodiment 1 of the present invention. In the transmission system shown in the figure, transmission apparatuses 100 and 200 are provided on a transmission path between transmission-side terminals a and b and reception-side terminals c and d, and terminals transmitted from terminals a and b Data is received by terminals c and d after being relayed by transmission apparatuses 100 and 200. Although omitted in FIG. 1, terminals other than the terminals a to d may be connected to the transmission apparatuses 100 and 200.

  The transmission apparatus 100 relays the terminal data transmitted from the terminals a and b after synchronous multiplexing. Specifically, the transmission apparatus 100 includes terminal interfaces 110a and 110b, a cross-connect unit 120, and a transmission path interface 130.

  The terminal interfaces 110a and 110b are respectively connected to the terminals a and b via transmission lines such as optical fibers, and the terminal data received in predetermined frame units are crossed at the timing determined by the cross-connect unit 120. Output to the connect unit 120.

  The cross-connect unit 120 multiplexes terminal data output from the terminal interfaces 110 a and 110 b according to multiplexing information stored in advance, and outputs the obtained multiplexed data to the transmission path interface 130. Further, the cross-connect unit 120 determines the timing for outputting the terminal data from the terminal interfaces 110a and 110b based on the device clock specific to the transmission device 100, and instructs the terminal interfaces 110a and 110b for the determined timing. The determination of timing by the cross-connect unit 120 will be described in detail later.

  The transmission path interface 130 is connected to the transmission apparatus 200 via a transmission path such as an optical fiber, and transmits multiplexed data output from the cross-connect unit 120 in synchronization with the frame timing of the transmission path.

  The transmission apparatus 200 separates the multiplexed data transmitted from the transmission apparatus 100 into data for each destination terminal, and transmits the data obtained by the separation to the terminals c and d, respectively. Specifically, the transmission apparatus 200 includes a transmission path interface 210, a cross-connect unit 220, and terminal interfaces 230a and 230b.

  The transmission path interface 210 is connected to the transmission apparatus 100 via a transmission path such as an optical fiber, and outputs multiplexed data received in predetermined frame units to the cross-connect unit 220.

  The cross-connect unit 220 separates the multiplexed data output from the transmission path interface 210 into terminal data for each terminal in accordance with previously stored multiplexing information, and the obtained terminal data is a terminal interface corresponding to each terminal. 230a and 230b.

  The terminal interfaces 230a and 230b are connected to the terminals c and d via transmission lines such as optical fibers, respectively, and transmit terminal data output from the cross-connect unit 220 to the terminals c and d.

  FIG. 2 is a block diagram showing a main configuration of transmission apparatus 100 according to the present embodiment. Specifically, FIG. 2 shows an internal configuration of the terminal interfaces 110a and 110b and the cross-connect unit 120 according to the present embodiment. In FIG. 2, the terminal interfaces 110a and 110b include first-in first-out (FIFO) 111a and 111b and read control units 112a and 112b.

  The FIFOs 111 a and b temporarily hold terminal data a and b transmitted from the terminals a and b, respectively, in units of frames. Then, the FIFOs 111a and 111b output the terminal data a and b in the input order according to the control by the read control units 112a and 112b.

  The read control units 112 a and 112 b read terminal data from the FIFOs 111 a and 111 b at the read timing determined by the timing determination unit 122 (to be described later) in the cross connect unit 120 and output the terminal data to the cross connect unit 120.

  In FIG. 2, the cross-connect unit 120 includes a multiplexing information storage unit 121, a timing determination unit 122, an ACM (Address Control Memory) unit 123, and a selector unit 124.

  The multiplex information storage unit 121 stores in advance multiplex information that defines a temporal order when the terminal data a and b are multiplexed, and the stored multiplex information is stored in the timing determination unit 122 and the ACM unit 123. To supply.

  The timing determination unit 122 determines the read timing for reading data held in the FIFOs 111a and 111b of the terminal interfaces 110a and 110b based on the device clock and multiplexing information unique to the transmission device 100. Specifically, the timing determination unit 122 generates a frame timing indicating the length of one frame using the device clock, and the terminal data a and b are arranged in one frame in the order indicated by the multiplexing information. Thus, the read timing is determined. Therefore, when the terminal data a and b are arranged in, for example, the terminal data a and the terminal data b in one frame of the multiplexed data, the timing determination unit 122 sets the read timing of the terminal data a to the frame timing. It is determined that the timing is the head timing, and the terminal data b read timing is determined to be delayed by at least the length of terminal data a from the head of the frame timing. Then, the timing determination unit 122 instructs the read control units 112a and 112b of the corresponding terminal interfaces 110a and 110b to the determined read timing, respectively.

  The ACM unit 123 controls the selector unit 124 based on the multiplexing information, and causes the selector unit 124 to output any one of the terminal data a and b read by the read control units 112a and 112b. Specifically, the ACM unit 123 refers to the multiplexing information, and at the timing when the terminal data a is output from the read control unit 112a, the ACM unit 123 outputs the terminal data a from the selector unit 124, and the read control unit 112b outputs the terminal data a. At the timing when the data b is output, the terminal data b is output from the selector unit 124.

  The selector unit 124 arranges the terminal data a and b output from the read control units 112a and 112b in one frame according to the control of the ACM unit 123, and the terminal data a and b are defined by the multiplexing information. Outputs multiplexed data multiplexed in order. The ACM unit 123 and the selector unit 124 constitute a space switch that outputs while switching the terminal data a and b.

  Next, cross-connect processing in the transmission apparatus 100 configured as described above will be described with reference to the flowchart shown in FIG. Hereinafter, a case where one frame of terminal data a is composed of data 1, 2, and 3 and one frame of terminal data b is composed of data A and B will be described as an example.

  When the data transmitted from the terminals a and b are received by the transmission apparatus 100, they are input to the FIFOs 111a and 111b in the terminal interfaces 110a and 110b corresponding to the terminals a and b (step S101). Specifically, for example, as shown in FIG. 4, terminal data a including data 1, 2, and 3 in one frame is written as write data a in the FIFO 111a, and terminal data b including data A and B in one frame. Is written in the FIFO 111b as the write data b. The write data a and b written in the FIFOs 111a and 111b are held by the FIFOs 111a and b until the read timing comes.

  On the other hand, the timing determination unit 122 in the cross-connect unit 120 determines the read timing of the write data a and b written in the FIFOs 111a and 111b (step S102). Specifically, the timing determination unit 122 generates the frame timing using the device clock, and further refers to the multiplexing information, thereby offsetting the offset from the head of the frame that reproduces the data arrangement within one frame. Is determined for each of the write data a and b.

  Then, the determined offset for each of the write data a and b is instructed to the read control units 112a and 112b as a read timing by the timing determination unit 122 (step S103). At this time, the read timing of the write data a is instructed to the read control unit 112a, and the read timing of the write data b is instructed to the read control unit 112b.

  In the read control units 112a and 112b instructed for the respective read timings, it is always determined whether or not the read timing has come (step S104), and the arrival of the read timing is awaited (No in step S104). When the read timing arrives (step S104 Yes), the read control units 112a and 112b output the terminal data a and b from the FIFOs 111a and 111b (step S105). Specifically, for example, as shown in FIG. 4, terminal data a including data 1, 2, and 3 is read out from the FIFO 111a as read data a at a timing delayed by an offset 301 from the head of the frame, and from the head of the frame. Terminal data b including data A and B is read from the FIFO 111b as read data b at a timing delayed by the offset 302.

  In FIG. 4, offsets 301 and 302 are determined so that the temporal positions of the terminal data a and b indicated by the multiplexing information are reproduced in the frame, respectively. And data A and B do not overlap each other, and all data are arranged at different times.

  When the selector unit 124 is controlled by the ACM unit 123, the data from the read control unit 112a is output from the selector unit 124 and the read data b is read at the timing when the read data a is read. The data is switched so that the data from the read control unit 112b is output from the selector unit 124. As a result, multiplexed data in which the terminal data a and b are arranged in one frame is generated by the selector unit 124 (step S106), and the cross-connect processing by the transmission apparatus 100 is completed. Specifically, for example, read data a and read data b shown in FIG. 4 are selectively output from the selector unit 124 at the read timing, and the data 1, 2, 3, A, and B are included in one frame. The arranged multiplexed data is generated.

  Thus, in the present embodiment, the read timing of the terminal data a and b from the FIFOs 111a and 111b is adjusted, and the terminal data a and b read at the read timing are arranged in the frame as they are. Even without a time switch, it is possible to execute a cross-connect process for generating multiplexed data in which a plurality of terminal data a and b are multiplexed.

  As described above, according to the present embodiment, terminal data transmitted from different terminals is held in the FIFO, and the read timing for reproducing the temporal position in the frame defined for each terminal data is determined. When the determined read timing arrives, the terminal data is read from the FIFO and multiplexed. For this reason, it is not necessary to adjust the time position of terminal data using a time switch, terminal data read from the FIFO can be immediately multiplexed, and data delay in the transmission path can be reduced. Can do.

(Embodiment 2)
The feature of the second embodiment of the present invention is that the time at which the terminal data is held by the FIFO is shortened by adjusting the write timing at which the terminal data is written into the FIFO, and further the data delay is reduced.

  Since the schematic configuration of the transmission system according to the present embodiment is the same as that of the first embodiment (FIG. 1), description thereof is omitted. In the present embodiment, the internal configuration of the transmission apparatus 100 is different from that of the first embodiment (FIG. 2).

  FIG. 5 is a block diagram showing a main configuration of transmission apparatus 100 according to the present embodiment. Specifically, FIG. 5 shows an internal configuration of the terminal interfaces 110a and 110b and the cross-connect unit 120 according to the present embodiment. In this figure, the same parts as those in FIG. In FIG. 5, the terminal interfaces 110a and 110b have write control units 401a and 401b and FIFOs 402a and 402b.

  The write control units 401a and 401b write terminal data to the FIFOs 402a and 402b at a write timing determined by a timing determination unit 403 (to be described later) in the cross-connect unit 120. Specifically, the write control units 401a and 401b receive a write timing instruction from the timing determination unit 403, and when the instructed write timing arrives, the write control units 401a and 401b receive the terminal data a and b transmitted from the terminals a and b, respectively. Write to the FIFOs 402a and 402b. At this time, the write controllers 401a and 401b request the terminals a and b to transmit the terminal data a and b prior to the write timing so that the terminal data a and b can be written at the write timing. May be.

  The FIFOs 402a and 402b temporarily hold the terminal data a and b transmitted from the terminals a and b, respectively, in units of frames. Then, the FIFOs 402a and 402b hold the terminal data a and b for the minimum delay time uniformly generated for all data, and then output the terminal data a and b in the input order.

  In FIG. 5, the cross-connect unit 120 includes a multiplexing information storage unit 121, a timing determination unit 403, an ACM unit 123, and a selector unit 124.

  The timing determination unit 403 determines a write timing for writing data to the FIFOs 402a and 402b of the terminal interfaces 110a and 110b based on the device clock and multiplexing information unique to the transmission device 100. Specifically, the timing determination unit 403 generates frame timing using the device clock, and determines the write timing so that the terminal data a and b are arranged in the order indicated by the multiplexing information within one frame. To do. That is, the timing determination unit 403 takes into account the minimum delay time in the FIFOs 402a and 402b, and writes the terminal data a and b read from the FIFOs 402a and 402b so as to reproduce the temporal arrangement indicated by the multiplexing information. Determine timing. Accordingly, the timing determination unit 403 sets the timing earlier than the temporal position of the terminal data a and b indicated by the multiplexing information by the minimum delay time as the write timing. Then, the timing determination unit 403 instructs the write control units 401a and 401b of the corresponding terminal interfaces 110a and 110b to the determined write timing, respectively.

  Next, cross-connect processing in the transmission apparatus 100 configured as described above will be described with reference to the flowchart shown in FIG. In the following, a case where one frame of terminal data a is composed of data 1, 2, and 3 and one frame of terminal data b is composed of data A and B will be described as an example.

  In the present embodiment, the timing determination unit 403 in the cross-connect unit 120 first determines the write timing for writing the terminal data a and b into the FIFOs 402a and 402b (step S201). Specifically, the timing determination unit 403 generates a frame timing using the device clock, and further refers to the multiplexing information, so that the multiplexed data has the same length as one frame of the multiplexed data. A terminal period unique to the terminal with the head of one frame as a reference is determined. That is, for example, as shown in FIG. 7, the terminal period a starting from the timing earlier by the offset 501 is determined with reference to the head of one frame of the multiplexed data, and the terminal period starting from the timing delayed by the offset 502 b is determined.

  In FIG. 7, offsets 501 and 502 take into account the delay time associated with the processing when the write control units 401a and 401b write the terminal data a and b to the FIFOs 402a and 402b and the minimum delay time in the FIFOs 402a and 402b. The terminal data a and b written in the FIFOs 402a and 402b are determined to be read from the FIFOs 402a and 402b at a timing to reproduce the temporal data arrangement indicated by the multiplexing information. That is, if the write control units 401a and 401b write the terminal data a and b into the FIFOs 402a and 402b simultaneously with the start of the terminal cycles a and b, the terminal data a and b are converted into the FIFOs 402a and 402b at the timing indicated in the multiplexing information. It is read from 402b.

  When the terminal periods a and b are determined by the timing determination unit 403, the determined terminal periods a and b are instructed to the write control units 401a and 401b as the write timing (step S202). At this time, the terminal cycle a is instructed as the write timing of the write control unit 401a, and the terminal cycle b is instructed as the write timing of the write control unit 401b.

  In the write control units 401a and 401b instructed for the respective write timings, it is always determined whether or not the write timing has come (step S203), and the arrival of the write timing is awaited (No in step S203). During this time, the write control units 401a and 401b transmit the terminal data a and b to the terminals a and b so that the terminal data a and b are received by the terminal interfaces 110a and 110b in accordance with the arrival of the write timing. May be required.

  When the write timing comes (Yes in step S203), the terminal data a and b are input to the FIFOs 402a and 402b by the write control units 401a and 401b (step S204). Specifically, for example, as shown in FIG. 7, when the terminal period a starts, terminal data a including data 1, 2, and 3 is delayed from the beginning of the frame by a predetermined delay time associated with the writing process. When the terminal cycle b is written as the write data a in the FIFO 402a, the terminal data b including the data A and B is written as the write data b at a timing delayed by a predetermined delay time associated with the writing process from the head of the frame. It is written in the FIFO 402b.

  After the terminal data a and b are written in the FIFOs 402a and 402b, respectively, when the minimum delay time elapses in the FIFOs 402a and 402b, the terminal data a and b are output from the FIFOs 402a and 402b to the selector unit 124 (step S205). . Specifically, for example, as shown in FIG. 7, the read data a and b are transferred from the FIFOs 402a and 402b to the selector unit 124 at a timing delayed by a minimum delay time corresponding to one data from the timing at which the write data a and b are written. Is output. These read data a and b reproduce the temporal arrangement of data indicated by the multiplexing information.

  When the selector unit 124 is controlled by the ACM unit 123, the data from the FIFO 402a is output from the selector unit 124 at the timing when the read data a is read, and from the FIFO 402b at the timing when the read data b is read. Are switched so as to be output from the selector unit 124. Thereby, the selector unit 124 generates multiplexed data in which the terminal data a and b are arranged in one frame (step S206), and the cross-connect processing by the transmission apparatus 100 is completed. Specifically, for example, the read data a and the read data b shown in FIG. 7 are selectively output from the selector unit 124 at the read timing, and the data 1, 2, 3, A, and B are included in one frame. The arranged multiplexed data is generated.

  As described above, in the present embodiment, the terminal data a and b write timings to the FIFOs 402a and 402b are adjusted, and the terminal data held in the FIFOs 402a and 402b for the minimum delay time after being written at the write timing, respectively. Since a and b are read and arranged in the frame as they are, it is possible to execute cross-connect processing for generating multiplexed data in which a plurality of terminal data a and b are multiplexed without a time switch. It becomes. Further, since the terminal data a and b are held in the FIFOs 402a and 402b only for the minimum delay time, the delay time in the FIFOs 402a and 402b can be reduced to the minimum. Therefore, if the transmission device 100 receives the terminal data a and b simultaneously with the write timing, the delay time in the entire transmission device 100 can be further shortened.

  As described above, according to the present embodiment, the write timing to the FIFO is determined so that the terminal data is read from the FIFO at a temporal position within the frame defined for each terminal data. When the write timing arrives, terminal data is written into the FIFO. For this reason, it is not necessary to adjust the time position of the terminal data using the time switch, the terminal data read from the FIFO can be immediately multiplexed, and the data delay in the transmission path is reduced. Can do. Further, since the delay time in the FIFO is only the minimum delay time, the delay in the entire transmission apparatus can be further reduced by receiving the terminal data from the terminal in accordance with the write timing.

(Embodiment 3)
A feature of the third embodiment of the present invention is that a time switch is used as necessary to reduce the delay while allowing the data order to be changed.

  Since the schematic configuration of the transmission system according to the present embodiment is the same as that of the first embodiment (FIG. 1), description thereof is omitted. In the present embodiment, the internal configuration of the transmission apparatus 100 is different from that of the first embodiment (FIG. 2).

  FIG. 8 is a block diagram showing a main configuration of transmission apparatus 100 according to the present embodiment. Specifically, FIG. 8 shows an internal configuration of the cross-connect unit 120 according to the present embodiment. In this figure, the same parts as those in FIG. In FIG. 8, the cross-connect unit 120 includes double buffers 601 a and 601 b, a multiplexing information storage unit 121, a data arrangement determination unit 602, a timing determination unit 122, an ACM unit 123, and a selector unit 124.

  Each of the double buffers 601a and 601b includes a first buffer and a second buffer. While the terminal data a and b output from the terminal interfaces 110a and 110b are written in one buffer, the other buffer is stored in the other buffer. The held terminal data a and b are read and output to the selector unit 124. FIG. 8 illustrates a state in which the terminal data a and b are written in the first buffer and the terminal data a and b are read from the second buffer.

  The double buffers 601a and 601b exchange the temporal positions of the terminal data a and b transmitted from the same terminal by writing and reading the terminal data a and b to and from the first buffer and the second buffer. That is, the double buffers 601a and 601b read the terminal data a and b for one frame in a desired order from the first buffer after the terminal data a and b for one frame are written in the first buffer, for example. To the unit 124. Thereby, the double buffers 601a and 601b can freely change the temporal positions of the terminal data a and b in one frame. That is, the double buffers 601a and 601b constitute a time switch in the present embodiment.

  The data arrangement determination unit 602 refers to the multiplexing information, and determines whether or not the temporal positions of the terminal data a and b need to be replaced when the terminal data a and b are multiplexed. Specifically, the data arrangement determination unit 602 determines, from the multiplexing information, for example, whether or not the terminal data a needs to be multiplexed after changing the temporal order of the data. Similarly, the data arrangement determination unit 602 also determines from the multiplexing information whether or not the terminal data b needs to be multiplexed after changing the temporal order of the data. Then, the data arrangement determination unit 602 outputs a determination result on whether or not replacement is necessary to the timing determination unit 122 together with the multiplexing information.

  In the present embodiment, the timing determination unit 122 determines the read timing for the terminal data a and b that need to change the temporal order of the data as a result of the determination by the data arrangement determination unit 602. The corresponding terminal interfaces 110a and 110b are instructed to read the terminal data a and b from the FIFO and output them to the double buffers 601a and 601b. In addition, as a result of the determination by the data arrangement determination unit 602, the timing determination unit 122 determines the read timing for the terminal data a and b that do not need to be replaced before and after the data as in the first embodiment. The corresponding terminal interfaces 110a and 110b are instructed to read the terminal data a and b from the FIFO at the determined read timing and output them to the selector unit 124.

  As described above, in the present embodiment, it is determined by the data arrangement determination unit 602 whether or not it is necessary to replace the temporal position of the data for each of the terminal data a and b. The terminal data a and b held in the FIFO are output to the double buffers 601a and 601b constituting the time switch, and the temporal positions are switched. For this reason, terminal data a and b that need to be exchanged are delayed in the double buffers 601a and 601b, but terminal data a and b that do not need to be exchanged are input to the double buffers 601a and 601b. In addition, the delay can be reduced.

  FIG. 9 is a diagram illustrating a specific example of multiplexed data generation according to the present embodiment. The figure shows a specific example in the case where terminal data a is terminal data that does not require a temporal position change, and terminal data b is terminal data that requires a temporal position change. Further, the fact that the terminal data a does not need to be temporally replaced while the terminal data b needs to be temporally replaced indicates that the multiplexing information stored in the multiplexing information storage unit 121 is in advance. Assume that it is stored.

  When the terminal data a and b are input to the terminal interfaces 110a and 110b, respectively, the terminal data a and b are written as write data a and b in the FIFO in the terminal interfaces 110a and 110b, respectively. In FIG. 9, data 1, 2, and 3 are included in one frame of write data a, data 4, 5, and 6 are included in the next frame, and data A, B is included.

  On the other hand, since it is determined that the terminal data a does not need to be exchanged by referring to the multiplexing information by the data arrangement determining unit 602, the terminal data is determined by the timing determining unit 122 as in the first embodiment. The read timing of a is determined, and the terminal data a is read from the FIFO as read data a at the determined read timing, and is output to the selector unit 124. Here, as shown in FIG. 9, the timing delayed by one data from the head of the frame is the read timing.

  Further, since it is determined that the terminal data b needs to be replaced, the timing determination unit 122 does not determine the read timing, and the terminal data b is read from the FIFO as the read data b, and the double buffer 601b. Are written in one of the buffers (for example, the first buffer). Then, after the terminal data b for one frame is written in the buffer of the double buffer 601b, the terminal data b is read out while changing the order of the data at the time corresponding to the next frame, and is selected as replacement data b. It is output to 124. Here, as shown in FIG. 9, the order of the data A and B constituting the read data b is changed, and the replacement data b is arranged in the order of the data B and A.

  At this time, the replacement data b is output to the selector unit 124 after a delay time of one frame in the double buffer 601b. Therefore, from the terminal interface 110a having no delay due to the time switch, the data 4 of the next frame is output. Read data a including 5 and 6 is output to the selector unit 124 at the read timing. Therefore, as shown in FIG. 9, the multiplexed data output from the selector unit 124 is obtained by multiplexing terminal data a that is not delayed and terminal data b that is delayed by one frame.

  As described above, according to the present embodiment, it is determined for each terminal data whether or not the temporal position of the data needs to be replaced, and a time switch is used for the terminal data that needs to be replaced. On the other hand, for the terminal data that does not need to be exchanged, the read timing from the FIFO is determined and output from the FIFO at the determined read timing. For this reason, the time position of data can be switched as necessary, and the delay of terminal data that does not require time position replacement can be reduced.

  In the third embodiment, the timing determination unit 122 determines the read timing from the FIFO. However, like the timing determination unit 403 in the second embodiment, the write timing to the FIFO is determined. You may do it. In this case, the write timing to the FIFO is determined only for the terminal data that does not require temporal position replacement.

  In each of the above embodiments, the transmission apparatus 100 executes the cross-connect process for multiplexing the terminal data. This process is described as a computer-readable program, and this program is It can also be executed by a computer.

  Regarding the above embodiment, the following additional notes are disclosed.

(Supplementary Note 1) Holding means for separately holding a plurality of terminal data transmitted from different terminals,
An adjusting unit that adjusts the timing at which each terminal data is output from the holding unit, based on a data arrangement in a predetermined frame when the terminal data is multiplexed in a frame;
A synchronization multiplexing transmission apparatus comprising: multiplexing means for multiplexing terminal data output from the holding means at a timing adjusted by the adjusting means.

(Appendix 2) The adjusting means includes
Determining means for determining a write timing for writing each of the plurality of terminal data to the holding means;
Write control means for writing the plurality of terminal data to the holding means at the write timing determined by the determination means;
The multiplexing means includes
The synchronous multiplexing transmission according to claim 1, wherein after the writing by the writing control means, the terminal data output after being held in the holding means for a predetermined minimum holding time is multiplexed simultaneously with the output. apparatus.

(Supplementary Note 3) The writing control means includes:
3. The synchronous multiplexing transmission apparatus according to appendix 2, wherein each of the plurality of terminal data is transmitted from a terminal in accordance with the write timing determined by the determining means.

(Appendix 4) The adjusting means includes
Determining means for determining a read timing for reading each of the plurality of terminal data from the holding means;
Read control means for reading the plurality of terminal data from the holding means at the read timing determined by the determining means,
The multiplexing means includes
The synchronous multiplexing transmission apparatus according to appendix 1, wherein the terminal data read by the reading control means is multiplexed simultaneously with reading.

(Additional remark 5) It further has the determination means which determines whether replacement of the time position of the data which comprises each terminal data is required,
The adjusting means includes
The synchronous multiplexing transmission apparatus according to appendix 1, wherein the timing output from the holding unit is adjusted only for terminal data that does not require replacement as a result of the determination by the determination unit.

(Additional remark 6) As a result of the determination by the determination means, it further has a replacement means for replacing the temporal position of the data constituting the terminal data that needs to be replaced,
The multiplexing means includes
The terminal data output from the holding unit at the timing adjusted by the adjusting unit and the terminal data obtained by exchanging the temporal position of the data by the replacing unit are multiplexed. 5. The synchronous multiplexing transmission device according to 5.

(Supplementary note 7) A synchronous multiplex transmission method in a synchronous multiplex transmission apparatus provided with holding means for separately holding a plurality of terminal data transmitted from different terminals,
An adjustment step of adjusting the timing at which each terminal data is output from the holding means, based on a data arrangement in a frame defined in advance when the plurality of terminal data are multiplexed in a frame;
And a multiplexing step of multiplexing terminal data output from the holding means at the timing adjusted in the adjusting step.

(Supplementary Note 8) A synchronous multiplexing transmission program executed by a computer having holding means for separately holding a plurality of terminal data transmitted from different terminals, the computer including:
An adjustment step of adjusting the timing at which each terminal data is output from the holding means, based on a data arrangement in a frame defined in advance when the plurality of terminal data are multiplexed in a frame;
And a multiplexing step of multiplexing terminal data output from the holding means at the timing adjusted in the adjustment step.

  The present invention can be applied to a case where data delay in a transmission path is reduced.

1 is a block diagram showing a schematic configuration of a transmission system according to Embodiment 1. FIG. 3 is a block diagram showing a main configuration of the transmission apparatus according to Embodiment 1. FIG. FIG. 5 is a flowchart showing cross-connect processing according to the first embodiment. 6 is a diagram showing a specific example of multiplexed data generation according to Embodiment 1. FIG. FIG. 6 is a block diagram illustrating a main configuration of a transmission apparatus according to a second embodiment. FIG. 10 is a flowchart showing a cross-connect process according to the second embodiment. It is a figure which shows the specific example of the multiplexed data generation which concerns on Embodiment 2. FIG. FIG. 10 is a block diagram illustrating a main configuration of a transmission apparatus according to Embodiment 3. FIG. 10 is a diagram illustrating a specific example of multiplexed data generation according to the third embodiment. It is a block diagram which shows the structure of the multiplexing apparatus using a time switch.

Explanation of symbols

110a, 110b Terminal interface 111a, 111b, 402a, 402b FIFO
112a, 112b Read control unit 401a, 401b Write control unit 120 Cross-connect unit 121 Multiplexed information storage unit 122, 403 Timing determination unit 123 ACM unit 124 Selector unit 601a, 601b Double buffer 602 Data arrangement determination unit

Claims (7)

Holding means for separately holding a plurality of terminal data transmitted from different terminals;
An adjusting unit that adjusts the timing at which each terminal data is output from the holding unit, based on a data arrangement in a predetermined frame when the terminal data is multiplexed in a frame;
A synchronization multiplexing transmission apparatus comprising: multiplexing means for multiplexing terminal data output from the holding means at a timing adjusted by the adjusting means. The adjusting means includes
Determining means for determining a write timing for writing each of the plurality of terminal data to the holding means;
Write control means for writing the plurality of terminal data to the holding means at the write timing determined by the determination means;
The multiplexing means includes
2. The synchronous multiplexing according to claim 1, wherein after the writing by the writing control means, the terminal data outputted after being held in the holding means for a predetermined minimum holding time is multiplexed simultaneously with the output. Transmission equipment. The writing control means includes
3. The synchronous multiplexing transmission apparatus according to claim 2, wherein each of the plurality of terminal data is transmitted from the terminal in accordance with the write timing determined by the determining means. The adjusting means includes
Determining means for determining a read timing for reading each of the plurality of terminal data from the holding means;
Read control means for reading the plurality of terminal data from the holding means at the read timing determined by the determining means,
The multiplexing means includes
2. The synchronous multiplexing transmission apparatus according to claim 1, wherein the terminal data read by said reading control means is multiplexed simultaneously with reading. It further comprises a determination means for determining whether or not replacement of the time position of data constituting each terminal data is necessary,
The adjusting means includes
2. The synchronous multiplexing transmission apparatus according to claim 1, wherein, as a result of determination by the determination unit, the timing output from the holding unit is adjusted only for terminal data that does not require replacement. A synchronization multiplexing transmission method in a synchronization multiplexing transmission apparatus provided with holding means for separately holding a plurality of terminal data transmitted from different terminals,
An adjustment step of adjusting the timing at which each terminal data is output from the holding means, based on a data arrangement in a frame defined in advance when the plurality of terminal data are multiplexed in a frame;
And a multiplexing step of multiplexing terminal data output from the holding means at the timing adjusted in the adjusting step. A synchronous multiplexing transmission program executed by a computer provided with holding means for separately holding a plurality of terminal data transmitted from different terminals, the computer comprising:
An adjustment step of adjusting the timing at which each terminal data is output from the holding means, based on a data arrangement in a frame defined in advance when the plurality of terminal data are multiplexed in a frame;
And a multiplexing step of multiplexing terminal data output from the holding means at the timing adjusted in the adjustment step.

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