JP3487327B2 - PDS transmission method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a management cell generation / transmission / processing mechanism used in a PDS (Passive Double Star) transmission system using an optical fiber.

[0002]

2. Description of the Related Art A general operation explanation of a PDS transmission system and an AT
A brief description will be given of the OAM cell used for M transmission. The related literature that has become publicly known is "Takiga
wa, Aoyagi, Maekawa: "ATM based passive Double Star s
ystem offering B-ISDN, N-ISDN, and POTS ", IEEE Global
Telecommunications Conference, page 14-18, Nov, 199
There is 3 ".

[Outline of operation of PDS transmission system] First,
To facilitate the following explanation, some assumptions and terms are defined. The main signal to be transmitted using this PDS transmission method is a standard 53-byte AT as an example.
The description will proceed with the form (format) of the M cell. Of course, the main signal may be any signal as long as it is a cellized signal. Here, the PDS is an optical branching / passive component.
This means that one optical fiber and a large number of optical fibers are connected via a merging function and star-connected to form a star wiring. Further, when bidirectional communication is performed using an optical fiber, the fiber through which light travels may be upstream or downstream, or WDM (wavelength multiplex) or FDM (multiplexing technology using wavelengths closer to each other than WDM). ), A fiber may be shared by using a technique such as an optical circulator.

FIG. 24 shows P in the range necessary for explaining the present invention.
The schematic block diagram of DS transmission system is shown. In general, a PDS transmission system constituent device has an SLT (Subs) installed on the center side.
criber line terminal) 100 and a plurality of ONUs (Optical Network Units) 110 installed in the user's house,
It is composed of an optical fiber connecting the SLT and the ONU and a star coupler. Here, the SLT 100 is in control of the timing, that is, the ONU 110 is the SL.
Paying attention to the fact that the signal is transmitted at the timing designated from T100, the SLT will be referred to as a main device and the ONU will be referred to as a slave device hereinafter.

As for the downlink main information transmitted from the main device to the slave device, the main information input from an external device (not shown) is transmitted to the intra-station interfaces 101-1 to 101-i by the main device internal format and the intra-station Performs the conversion of standard interfaces connected through the interface. When transmitting ATM cells, the current standard intra-station interface format is SDH (Synchronous
This is a structure in which ATM cells are placed in the payload on the frame of Digital Hierarchy format, and when an abnormality occurs between the main device and the external device connected to it or between devices further away, it is defined on the header of this SDH format. According to the procedure described above, another alarm is returned to the adjacent device, or an alarm is issued to the maintenance person via the monitoring system of the main device. Further, another procedure is defined when the main signal itself is disconnected or a bit error occurs, and the procedure is dealt with according to this. If such an abnormality is not detected, the SDH header is once removed and a SDH header is newly added to the subsequent device and only the SDH payload is transmitted. This function is called a function of terminating the SDH header. An ATM cell is mainly used as the in-device format. Further, as an external device connected to the intra-station interface 101, there is a line (path) setting device called a cross connector.

Main information output from the intra-station interfaces 101-1 to 10-1 by the ATM cross-connect switch (hereinafter referred to as ATM-SW) 102 in the main device 100 is the purpose among the transmission line interfaces 103-1 to 10-j. To the transmission line interface,
After conversion for PDS such as attaching a PDS cell header in the transmission path interface, electric-optical conversion is performed and the signal is sent to the optical fiber 104. The cell format at that time is, as shown in FIG.
This is a configuration in which information for PDS is added to a cell and is called a PDS cell. Here, a PDS cell sent from the main device 100 to the slave device 110 is called a downlink PDS cell, and a PDS cell sent from the slave device 110 to the main device 100 is called an upstream PDS cell.

The above-mentioned downlink PDS cell is broadcast to a plurality of slave devices. Here, in FIG. 24, the slave device 1 connected to the transmission path interface 103-2 is shown.
Although only 10-1 to 10-n are shown, it is assumed that other transmission line interfaces are also connected to a plurality of slave devices, respectively. The PDS cell has its header with DI in FIG.
Since the destination slave device number is assigned as D, all slave devices read the header once, and the slave devices whose DID and the device number match each other take in the payload internally, and the slave devices which do not match read the header. Then, the PDS cell is discarded.

On the other hand, upstream PDS cells transmitted from the slave device to the master device enter the transmission timing waiting buffer 111 in the slave device as shown in FIG. 24, and are transmitted to the slave device at an appropriate timing. It is transmitted to the optical fiber 105 via the path interface 112. Here, in FIG. 24, only the configuration in the slave device 110-n is illustrated, but it is assumed that other slave devices have the same configuration. The appropriate timing will be described. The master device delivers the same PDS cell to all slave devices. Each slave sees the DID of each PDS cell,
The PDS cell addressed to its own device is taken inside, and the irrelevant PD
The S cell is discarded. On the other hand, the upstream P from the slave device
As shown in FIG. 24, since the DS cells are combined by an optical branching / combining function, for example, a star coupler (SC) 106, it is necessary to perform scheduling so that cells transmitted from each slave device do not collide. Scheduling is performed by the main device 10
0, and notifies each slave device of the timing at which transmission can be performed using the transmission-permitted slave device number PID included in the downlink PDS cell in FIG.

FIG. 26 shows an outline of the control procedure of the apparatus.
The device number of the slave device 1 is described in the PID of the downlink PDS cell # 1, which indicates that the master device has given the slave device 1 permission to transmit the uplink signal. When the slave device 1 receives the downlink PDS cell # 1, the slave device 1 transmits the uplink signal after the delay time d1. Similarly, the slave device i transmits an upstream signal with a delay time di after receiving the downstream PDS cell #i. These delay times dk are set to be shorter as the distance between the master unit and the slave unit is longer.
Specifically, when a certain predetermined time T is set and the transmission time from the master device to the slave device k is Tk, the delay time dk is given by dk = T-2 * Tk. Therefore, after transmitting the PID, the master device can receive the upstream signal from the slave device having the number corresponding to the PID after a predetermined time T.

However, since the delay time dk is indefinite at the time of start-up, a delay time measuring procedure for determining the delay time dk prior to communication is necessary in order to use the above-mentioned control procedure. Since the slave device is activated at any time for the convenience of the user, the delay time measurement procedure is executed even when another device is communicating. As a method to prevent the delay time measurement procedure from affecting other communications, define a test cell for delay time measurement and set the timing for sending the test cell to the slave device activated by the master device on the downlink. The slave device sends a test cell on the uplink at the instructed timing, and a delay measurement area for receiving only the test cell is periodically provided at the main device reception point for a fixed time, and the test cell arrives at the main device. It is generally performed to calculate the delay time from the time.

[Simple Description of Conventional ATM Transmission] In conventional ATM transmission, generally, there are a method of placing an ATM cell in the payload of SDH and a method in which there is no SDH frame, that is, full ATM. In the former, OAM (Operation, Administration and MAM) for alarms, bit errors, etc.
Most of the related information is defined in the SDH header. In the latter, OAM cells are appropriately defined and transferred only at the minimum necessary. In any case, the form of the transmission line is 1: 1 and, therefore, PDS transmission cannot be performed by these means.

[Simple Description of OAM Cell Conventionally Used in ATM Transmission System] A term of the conventional ATM transmission area is an OAM cell. This is a cell that is sent out as needed and when needed, and if there is no action for abnormality or maintenance, communication is possible if the main information cell can be transferred even if the OAM cell is not sent out. The OAM cell transmission method is a method of monitoring the main information cell flow and replacing it with an OAM cell and transmitting it when an empty cell arrives.

[Simple Description of Conventional ATM Multiplexing] One function of the conventional ATM transmission system is ATM multiplexing. The ATM multiplexing means to sequentially transmit cells having different types and destinations in cell units, which is a concept different from the conventional frequency multiplexing, bit multiplexing, and burst multiplexing, and is also called label multiplexing. In burst multiplexing, bursts of the same type are periodically multiplexed. In ATM multiplexing, however, the transmission order is probabilistic, so it is also called statistical multiplexing. Therefore, the conventional ATM OAM cell is transmitted by replacing it with a stochastically present empty cell, and therefore cannot be transmitted accurately and periodically.

[0014]

In the PDS transmission system,
Normally, it is desired to match the cycle in which the delay measurement area is provided with the above-mentioned T to form a frame with T as a unit time, and manage the OAM related information in units of this frame. However, in the conventional PDS, it is relatively easy to identify a frame using a specific cell, but it is impossible to transmit / receive the OAM management information between the master device and each slave device in every cycle T0. It was Therefore, PDS
The evaluation of the transmission path was performed based on the error rate evaluation in the payload part after restoring the payload of the transmitted cell. In this evaluation method, if the header part of the cell is incorrect, the entire cell is lost, so that there is a drawback that accurate evaluation cannot be performed in bit units.

The present invention has been made in view of the above-mentioned circumstances, and has a means for transferring management information unique to the PDS transmission system between the main device and the slave device, and is a one-to-many connection P
It is an object of the present invention to provide a PDS transmission method that enables a DS device to operate normally.

[0016]

[0017]

[0018]

According to a first aspect of the present invention, one master unit and a plurality of slave units are connected in a star shape, and the main unit and each slave unit are connected in cell units. In the PDS transmission method for transmitting information, the master device transmits a downlink individual management cell for notifying the slave device of management information about each slave device, and each slave device manages the downlink individual management addressed to itself. In the PDS transmission method of selecting and receiving cells, the main device instructs a vacant cell detection unit that detects an output of a vacant cell and generation and insertion of an individual management cell based on the detection result of the vacant cell detection unit. An individual management cell transmission control unit, an individual management cell generation unit that generates an individual management cell based on an instruction to generate an individual management cell from the individual management cell transmission control unit, and stores the individual management cell in an individual management cell buffer, and the individual management cell And an individual management cell insertion unit that inserts the individual management cell generated in the individual management cell generation unit in place of the empty cell and sends out to the slave device based on an instruction to insert the individual management cell from the output control unit. If the number of dedicated management cells accommodated in the dedicated management cell buffer becomes equal to the number of PDS cells that can be transmitted by the end of the frame period in which the dedicated management cell has occurred,
This is a PDS transmission method characterized in that cells other than empty cells are temporarily accommodated in an information cell buffer and all PDS cells to be transmitted in the remaining time of the frame cycle are used as individual management cells.

According to a second aspect of the present invention, one main device and a plurality of slave devices are connected in a star shape, and PDS transmission for transmitting information in cell units between the master device and each slave device. A PDS transmission method in which each of the slave devices transmits an uplink individual management cell for notifying the master device of management information regarding the slave device, and the master device receives the uplink individual management cell In the above, each slave device includes an empty cell detection unit that detects an output of an empty cell, an individual management cell transmission control unit that instructs generation and insertion of an individual management cell based on a detection result by the empty cell detection unit, and An individual management cell generation unit that generates an individual management cell based on an instruction of the individual management cell transmission control unit to generate the individual management cell and stores it in the buffer for the individual management cell, and an individual management cell by the individual management cell transmission control unit. Based on a cell insertion instruction, an individual management cell insertion unit that inserts an individual management cell generated in the individual management cell generation unit in place of the empty cell and sends it to the main device, and for the individual management cell When the number of individual management cells accommodated in the buffer becomes equal to the number of PDS cells that can be transmitted by the end of the frame period in which the individual management cell occurs, cells other than empty cells are temporarily accommodated in the information cell buffer. The PDS transmission method is characterized in that all PDS cells to be transmitted in the remaining time of the frame period are dedicated management cells.

According to a third aspect of the present invention, one main device and a plurality of slave devices are connected in a star shape, and PDS transmission for transmitting information between the master device and each of the slave devices in cell units. In the method, the master device transmits a downlink individual management cell that notifies the slave device of management information about each slave device, and each slave device selects and receives the downlink individual management cell addressed to itself. In the PDS transmission method, the main device recognizes how many downlink dedicated management cells have already been transmitted and how many individual management cells have not been transmitted in the current frame period, and Having a grasping means for grasping how many cell time slots are left in, designating the timing of transmitting the downlink dedicated management cell within a frame period, at the timing of transmitting the downlink dedicated management cell, When the cell to be output is an empty cell, the cell is replaced with the empty cell and the downlink dedicated management cell is transmitted to the slave device. When the cell to be transmitted at the timing is an information cell other than the empty cell, the grasping means The PDS transmission method is characterized in that the information cell is temporarily accommodated in the information cell buffer on the basis of the grasped result and the downlink dedicated management cell is transmitted to the slave device.

[0021] According to a fourth aspect of the present invention, in the PDS transmission method according to the third aspect , the main unit performs the downlink at equal time intervals within a time region in which the downlink dedicated management cell can be transmitted. It is characterized by transmitting an individual management cell.

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION In the following respective embodiments, description will be made in the following order. First, in the downlink direction, define a common management cell for notifying all slave devices of common contents,
The function and effect will be explained. Next, in the downlink direction, for the downlink dedicated management cell for notifying the specific slave device of the management information about the slave device, then for notifying the management information about the own slave device and the master device in the uplink direction The uplink dedicated management cell will be described. Furthermore, the structure of the transmission mechanism for each cell is shown.

Here, an example of contents to be loaded in the above-mentioned various management cells will be shown. For example, in the case of the overall configuration of the PDS transmission system shown in FIG. 24, in the cell exchanged between the main device and the slave device, in addition to the main signal, closed management information related to the main device or the slave device itself, There is management information for network management other than the main signal, which is provided from an adjacent device (not shown) connected to each of the device and the slave device. These include, for example:

In the main signal waiting buffer 111 of the slave device 110, CLAD (cell) for converting the main signals other than the ATM signal of the external device (not shown) into ATM cells.
A circuit called assemble dis-assemble function) may be connected. The CLAD has a function of receiving a control signal from a maintenance person on the main device side to open / close a circuit and a function of notifying the main device side of an abnormality such as an overflow. These control / notification signals are put in the uplink dedicated management cell,
Communication is performed between a specific slave device and the master device.

The intra-station interface 101 of the main device 100 can be connected to a line (path) setting device called a cross connector, for example. The current intra-station interface format has a structure in which an ATM cell is placed in a payload on an SDH format frame, and when an abnormality occurs between devices or devices farther away, an alarm bit defined on the header of this SDH format is sent. Alarms are sent and received by using them. When these alarms are received, the alarms are placed in the downlink dedicated management cell as necessary to notify the slave device, or conversely the alarms generated by the external device connected to the slave device are transmitted as needed. It is placed in the individual management cell and notified inside the main equipment station.

An example of the management information closed between the main device and the slave device is a transmission error at the upstream or downstream receiving point of the optical transmission line. Specifically, the BIP in the frame on the transmission side
(BitInterleave Parity) The calculation result is placed on the management cell and notified to the reception side, the BIP of the signal received on the reception side is calculated, and the transmission error is measured by comparison with the BIP calculation result notified by the management cell. The measurement result is placed on the management cell and notified to the device that has transmitted the signal. As for the upstream signal, each slave device puts the BIP calculation result on the upstream dedicated management cell, and the master device reports the transmission error measurement result to each slave device by the downstream dedicated management cell. As for the downlink signal, the master device puts the BIP calculation result on the common management cell as described later, and each slave device notifies the main device of the transmission error measurement result by the uplink dedicated management cell. Hereinafter, each embodiment will be described with reference to the drawings.

[First Embodiment] In the present embodiment, the function and effect of the common management cell will be described. The common management cell is a kind of downlink PDS cell, and can be distinguished from other cells by a specific bit in the PDS header or the PDS cell payload. For example, as shown in FIG.
The cell type identification bit may be defined in the header. An example of bit definition will be described with reference to FIG. Two bits are prepared in the PDS cell header or PDS cell payload. This is b
If 1 and b2 are set, 4 types of PDS cells can be identified by these 2 bits.

For example, as shown in FIG. 2, (b1, b2)
By defining = (0,1) as a common management cell, it can be identified on the receiving side. Returning to the function of the common control cell. As shown in FIG. 3, the common management cell can notify all slave devices of the frame by transmitting in the downlink at regular intervals. In the figure, dd is shown to indicate that the start points of the upstream and downstream frame periods T do not have to match. What is important here is that the master device defines a downlink frame period T, notifies each slave device of the downlink frame period T, and each slave device transmits an uplink signal based on the notified frame period. Based on this frame, you can:

(1) When the slave device is started up, that is,
In order to measure the distance between the slave device and the master device, which is necessary at the time of startup, the specific slave device that receives the startup instruction receives the common management cell, and the frame cycle T (hereinafter, simply referred to as cycle T).
Since the window for distance measurement in the predetermined time region within the cycle T can be recognized by confirming, the cell for distance measurement can be transmitted without interfering with other slave devices in communication. The window for distance measurement is the delay measurement area described above, and when the distance between the master and slave devices is less than a specified value, its length is set so that it does not collide with cells sent by other slave devices in communication. Is set. Although it is arranged at the end of the frame in FIG. 3, it can be arranged at any point in the frame except at the common management cell arrival time. Since the common management cell is transmitted from the master device and received by each slave device in the cycle T, the start point of the distance measurement window is defined by the relative time from the common management cell, so that Can also recognize the temporal location of the distance measurement window.

More specifically, the slave device immediately after startup is
Since the distance between the main device and the slave device is unknown, the propagation delay time cannot be known, and therefore the appropriate transmission timing cannot be grasped. Therefore, the slave device cannot issue an upstream signal and request the master device to connect. Therefore, the master device sequentially sends the permission to send the test cells for distance measurement to all the slave devices that are registered in advance but does not respond, and when the slave device immediately after the start receives the permission to send, it starts the distance measurement window. Send a test cell to the main device at a time that seems to be,
When the master device receives the test cell in the distance measurement window, the master device knows that the slave device has started up and at the same time can determine the delay time shown in FIG. Since this transmission permission is issued to only one slave device per frame, it is desirable to embed it as information in the common management cell. As a result, the PD is sent to the master device at an accurate timing so as not to collide with the PDS cells emitted from other slave devices.
S cells can be sent. On the contrary, in order to determine the delay time, first, it is essential to notify the slave device of the cycle T by the common management cell. For the first time, the timing of sending the test cell to the distance measurement window can be known.

(2) By defining the period T, it can be expected that this common management cell will continue to arrive at the slave device periodically without interruption. When this common management cell is lost, it can be interpreted that an abnormality has occurred somewhere. For example, it may be considered that some kind of abnormality has occurred, such as a disconnection of an optical fiber, a failure of a main device or a power failure, and a failure of a receiving circuit inside a slave device. That is,
The slave device can obtain an alarm for detecting a received signal abnormality.

(3) As shown in FIG. 3, when the main device defines a cycle T by the emission interval of the common management cell and sends the number of downlink individual management cells expected within the cycle T by the receiving side. This can also be used as an abnormal state monitor, that is, as an abnormal state detection trigger. For example, if it is specified that the master device always sends a fixed number of downlink dedicated management cells to each slave device in communication within the period T, the number of downlink dedicated management cells received by the slave device within the period T. If is out of regulation, it is judged that communication is abnormal, and if transmission of PDS cells from the slave device is stopped,
It is possible to prevent useless cell collision in a star coupler or the like. That is, the sending can be stopped before the active sending command is issued from the main device, or without sending the sending sending command.

(4) By defining this common management cell, the notification contents common to all slave devices can be notified to each slave device without individually transferring the cell. If there are N slave devices, the required number of management cells can be reduced to 1 / N, and the number of cells allocated to the main signal cells can be increased.

(5) By placing the downlink BIP calculation result on the common management cell, it is possible to perform online monitoring of the downlink error rate. The BIP calculation result is transmitted together with the transmission data in each cycle T by the common or individual management cell, the reception data is BIP-calculated again at the reception point, and the result is collated with the BIP calculation result calculated by the transmission source at the same time. Is returned to the sender. In the downstream direction, the contents are transferred to all slave devices in the same way, so BI
Transferring the P calculation result in the common management cell is more efficient than sending it in the downlink dedicated management cell. In addition, BI
If the P operation results match, it is considered that no error has occurred, and if they do not match, the maintenance person can be notified as a transmission characteristic deterioration alarm.

As described above, it is useful in the PDS transmission method to periodically send the common management cell in the accurate cycle T.

[Second Embodiment] In the present embodiment, the first embodiment
The configuration of the common management cell transmission mechanism introduced in the embodiment will be specifically described. Since the common management cell is transmitted in the downlink direction, it is ATM-multiplexed with the downlink main signal cell. Here, the main signal cell is a significant ATM cell input to the PDS transmission apparatus from outside the PDS transmission system. Significant cells are user cells excluding cells for speed adjustment such as empty cells and idle cells, ATM-OAM cells and the like.

In the OAM cell transmission method described in the prior art, an empty cell is stochastically waited for. In the PDS transmission method, this method cannot notify the slave device of an accurate cycle, and therefore the transmission method shown in this embodiment is necessary.
Since the common management cell disclosed in the present application needs to be transmitted accurately and periodically, it is transmitted with the highest priority when the timing to transmit it comes. That is, the main signal cell, empty cell, AT
It is transmitted with priority over any M-OAM cell or the like.

The specific structure will be described below with reference to FIG. Here, of the configurations shown in this figure, the ATM-SW10
The configuration other than 2 corresponds to the configuration within the transmission path interface 103 of FIG. Further, in FIG. 1, the main signal cell flows from right to left in the figure. The ATM-SW1 is transmitted from an interface unit (not shown) in the station.
The main signal cell passing through 02 flows to the PDS cell header addition unit 3 via the cell buffer 2 and the PDS header is added, and in the management cell insertion unit 4, if the changeover switch is connected to the upper side in the figure, Electric-optical converter (E /
O) 5 and finally is sent out to an optical fiber connected to a plurality of slave devices. On the other hand, the cycle T generation counter 6
From this, accurate period T information is generated, and is notified to the common management cell generation unit 7 and the common management cell transmission control unit 8.
The common management cell generation unit 7 generates a predetermined number of common management cells each time the period T notification is received.

The common control cell transmission control section 8 performs the operation shown in FIG. That is, when it is time to send the common management cell or when the timing is approaching, a management cell transmission instruction is sent to the management cell buffer 9 and a common management cell insertion instruction is sent to the management cell insertion unit 4. Upon receiving these instructions, the management cell buffer 9 outputs one common management cell. Further, the management cell insertion unit 4 switches the switch to the lower side in the figure and sends the common management cell coming from the management cell buffer 9 to the electro-optical converter 5.

The common management cell transmission control unit 8 also issues an instruction to the cell buffer 2. This instruction is a cell standby instruction,
Make the main signal cell wait for the required period. That is, ATM-
When the cell coming from SW 102 is kept waiting, it is temporarily stored in the cell buffer 2 and is sent after sending the common management cell. When the cell coming from the ATM-SW 102 is an empty cell, it may be discarded without being reserved. The cell buffer 2
Instead of providing the above, the output buffer or the input buffer of the ATM-SW 102 may be provided with a mechanism for receiving an instruction for stopping the cell transmission, and the function of the cell buffer 2 may be realized by these buffers.

[Third Embodiment] FIGS. 5 and 6 show the construction of another common control cell transmission mechanism. The difference from FIG. 1 of the second embodiment is that the common management cell buffer 9 is not provided. As in the second embodiment described above, generation and transmission of the common management cell are performed in independent phases,
Once the generated common management cell is retained in the buffer, it is possible to design with a margin in timing margin in terms of equipment design, and it is not necessary to consider the transmission timing of the common management cell precisely. Cell generator 7
It can be expected that there is no problem in practical use because the retention time in the management cell buffer 9 is changed even if there is a slight design mistake.

However, in exchange for this, if the content to be notified changes while staying in the management cell buffer 9, the content will be placed in the next common management cell. Therefore, the meaning of the configuration shown in FIG. 5 comes out. That is, in the configuration of the present embodiment, the timing design becomes somewhat difficult, but since the common management cell is generated immediately before transmission, the latest contents can be loaded in the common management cell.
The operation of the figure is roughly the same as that of FIGS.
The difference is that in FIG. 1 and FIG. 4, the common management cell transmission control unit 8
From FIG. 5 and FIG. 6, the common management cell is being sent to the management cell buffer 9 and the common management cell is flowing to the management cell inserting section 4. . That is, the common management cell is
Immediately before the designated transmission timing, the common control cell transmission control unit 8
It is generated by the generation instruction issued from.

[Fourth Embodiment] In the present embodiment, a reception process of the above-mentioned common management cell on the slave side will be described. 8 shows a configuration of a common management cell reception processing mechanism in the device according to FIG. 7. The downlink PDS cell transmitted from the main device is optically converted by the optical-electrical converter (O / E) 10 in the slave device.
After being electrically converted, it enters the reception processing unit 11. When the PDS cell arrives, the reception processing unit 11 receives the bit synchronization unit 11a.
Extracts a clock for correct reproduction of the optical signal based on the optical signal coming from the opposite device, and reproduces a correct 1/0 signal from the optical signal. Also, the bit synchronization unit 1
1a also reproduces a byte cycle in units of 8 bits and correctly reproduces byte synchronization (also called word synchronization).

Then, the cell synchronization unit 11b uses the reproduced bit synchronization and byte synchronization to generate a PDS of 60 bytes.
Recognize cells correctly. Here, the slave device can specify (recognize) each bit position of the PDS header only when the cell synchronization is established, and can specify the start position of the ATM cell that is the payload. Then, the cell type recognition unit 1
In 1c, after recognizing the cell type from the cell type identification bit of the PDS header, the received PDS cell is sent to the internal circuit 12, and the contents defined in each bit of the PDS header are interpreted or the ATM cell is cut out. Transfer to an external device.

When the common management cell is identified by the cell type recognition unit 11c, the common management cell arrival period confirmation unit 13 is notified of the fact. Then, upon receiving the notification, the common control cell arrival cycle confirmation unit 13 performs the following processing. (1) At the time of initial startup of the slave device, the slave device does not know the starting point of the cycle T. Therefore, the initial value of the cycle T generation counter 14 is set based on the time point when the common management cell is received. (2) During communication, the arrival cycle of the common management cell is constantly monitored, and when the common management cell arrives at a timing other than the cycle, or when it does not arrive at the expected timing, that is, when a cell loss occurs. The alarm processing unit 15 is notified of an abnormal cycle or a cell loss occurrence according to each case.

When the alarm processing unit 15 receives the notification from the common management cell arrival period confirmation unit 13, the alarm processing unit 15 makes the following determination. (A) When the common management cell arrives at a timing other than the cycle (when an abnormal cycle is notified), it is determined that the phenomenon has been lost when the phenomenon continues for a predetermined number of K times, and a slave device (not shown) Notify the common processing unit of that fact and have them as a basis for making a decision such as a reset. (B) When the common management cell does not arrive at the expected timing (when there is a cell loss occurrence notification), it is instantly determined whether the cell loss has happened accidentally or the downstream fiber has been broken. Therefore, if the common management cell does not arrive for a predetermined number of M rounds, it is judged as abnormal and the common processing unit in the slave device (not shown) is notified. The common processing unit (not shown) in the slave device can recognize that an abnormality has occurred in the downlink PDS cell sequence and stop the uplink PDS cell of the slave device by receiving the notification. This function is important in order not to collide with PDS cells generated by other slaves.

[Fifth Embodiment] In the present embodiment, the configuration of the above-mentioned downlink dedicated management cell transmission mechanism will be described. First, in the main device of the present embodiment, the number of downlink dedicated management cells generated in the cycle T is specified. However, how accurately the downlink dedicated management cells are generated after the cycle is recognized in the main device. The realization method differs depending on whether or not. Therefore, a case will be described in the present embodiment where the relationship with the downlink common management cell that accurately notifies the cycle T does not have to be very accurate, and a case where it is desired to accurately transmit a predetermined number within the cycle T will be described. This will be described in the seventh and eighth embodiments. Although the cycle T is used as the reference cycle in the following embodiments, the reference cycle may be an integral multiple of T. In this case, the generation cycle of the counter may be nT (n is a natural number).

The details of the fifth embodiment will be described below. When the downlink dedicated management cell to be transmitted has a cycle, it depends on how accurate the cycle is requested, but the configuration of the transmission mechanism of the downlink dedicated management cell when the error width of the transmission cycle of the downlink dedicated management cell is allowed It shows in FIG. Here, the configuration shown in FIG. 8 is a configuration in which a downlink dedicated management cell is generated for one slave device.

The cycle T generation counter 6 notifies the accurate cycle T to the individual management cell transmission control section 20. The individual management cell transmission control unit 20 stores the number of individual management cells to be transmitted within one cycle T, and when receiving the empty cell detection notification from the empty cell detection unit 21, determines the number of individual management cells to be transmitted. If the number is greater than zero, the individual management cell generation unit 22 is instructed to generate and the management cell insertion unit 23 is instructed to insert the individual management cell. As a result, the management cell insertion unit 23
The changeover switch is changed to the lower side in the figure, the empty cell is discarded, the individual management cell is selected, and the individual management cell is sent to the electro-optical converter 5. Further, when the individual management cell transmission control unit 20 issues an instruction to insert the individual management cell, the individual management cell transmission control unit 20 decrements the stored number of transmissions by one, and when the next frame cycle is reached, one cycle T
The number of individual management cells to be transmitted is added to the storage, and is decremented by 1 for each individual management cell transmission.

Although the configuration shown in this figure does not have a buffer for the individual management cell, a buffer similar to the management cell buffer 9 of FIG. 1 described above is provided to temporarily generate the individual management cell. The configuration may be such that the individual management cell is output when the cell stays in the buffer and an empty cell is detected. This is shown in FIG. The operation of the individual management cell generation management unit 25 in the figure is shown in FIG.
The operation of is shown in FIG.

In these figures, the cycle T generation counter 6
Notifies the individual management cell generation management unit 25 of the accurate cycle T. At this time, the individual management cell generation management unit 25 issues a generation instruction to the individual cell generation unit 22 when the slave device is not stopped. The individual management cell generation unit 22 generates a predetermined number of individual management cells and sends them to the management cell buffer 24. Here, it goes without saying that the functions of the individual management cell generation management unit 25 and the individual management cell generation unit 22 may be realized in one constituent unit. Actually, since the function of the individual management cell generation management unit 25 is relatively simple, it is realistic to incorporate it into the individual management cell generation unit 22.

The management cell buffer 24 notifies the individual management cell transmission control section 20 of the presence / absence of cells to be transmitted. As shown in FIG. 11, the individual management cell transmission control unit 20 has an individual management cell to be transmitted in the management cell buffer 24, and the empty cell detection unit 21 detects an empty cell in the cell string output from the ATM-SW 102. When detecting and receiving a notification that there is an empty cell from the empty cell detection unit 21, it issues a management cell transmission instruction to the management cell buffer 24 and a management cell insertion instruction to the management cell insertion unit 23.

Then, the management cell inserting section 23 switches the changeover switch to the lower side in the figure, whereby the empty cell mixed with the main signal cell and the downlink individual management cell are exchanged and sent to the electrical-optical converter 5. To be done. ATM-SW102
Since the cells coming from the ATM are ATMs, empty cells can be expected stochastically, and empty cells can be expected with a high probability if there is a margin in the contract band of the main signal. However, since it is stochastic, even if the individual management cells are periodically put in the management cell buffer 24, the transmission cycle has an error width. Since this width is probabilistic, the possibility that the required number of individual management cells cannot be transmitted in the predetermined period T does not become zero. When this is disliked, the configuration of the seventh or eighth embodiment described later may be used.

[Sixth Embodiment] In the fifth embodiment,
Although the configuration is illustrated without referring to the number of slave devices, in the PDS transmission method, a plurality of slave devices are actually connected to the same transmission line interface of the main device as shown in FIG. That is, it is necessary to send the individual management cells to a large number of slave devices via the optical fibers. Therefore, FIG. 12 shows the configuration of a transmission mechanism of the downlink dedicated management cell when a plurality of slave devices are connected to the master device.

The basic operation of this structure follows the operation of the structure shown in the fifth embodiment. In this figure, the cycle T generation counter 6 notifies the individual management cell generation management unit 25 of an accurate notification of the cycle T. In the individual management cell generation unit 25, based on the operation shown in FIG. 10, the individual management cell generation units 22-1 to N (N is all slave devices connected to the transmission mechanism of FIG. 12) prepared for each slave device. (Indicates the number of cells in the above). Individual management cell generation unit 22
Upon receiving the cell generation instruction, each of the -1 to N generates a predetermined number of dedicated management cells in which the destinations of the slave devices to be transmitted and their contents are placed in the PDS cell,
It is passed to the cell multiplexing unit 26.

The PDS cell multiplexing unit 26 performs the conventional cell multiplexing, and notifies the individual management cell transmission control unit 20 of the number of significant cells accumulated. The individual management cell transmission control unit 20 sequentially makes a judgment for each individual management cell for each slave device based on the operation shown in FIG. 11, and instructs the PDS cell multiplexing unit 26 to transmit the individual management cell if the conditions are met. In addition, an insertion instruction is sent to the management cell insertion unit 23. As a result, the management cell insertion unit 23 switches the changeover switch to the lower side in the figure, and sends the individual management cell sent from the PDS cell multiplexing unit 26 to the electro-optical converter 5.

Note that this configuration can be modified in several ways. Although not shown, only the text will be described below. First, without providing the PDS cell multiplexing unit 26, as shown in FIG. 9, a management cell buffer is placed at the output of each individual management cell generation unit 22-1 to 22-n, and the output of each management cell buffer is wired-ORed. Then, the data is input to the management cell insertion unit 23. Then, each management cell buffer notifies the individual management cell transmission control unit 20 of the presence or absence of a staying cell, that is, the remaining cell, and the individual management cell transmission control unit 20 having received the notification excludes each management cell buffer. By giving a transmission instruction so that the individual management cell exits, the same function as the configuration shown in FIG. 12 can be realized.

[Seventh Embodiment] In the present embodiment, a configuration is shown in which it is desired to accurately transmit a predetermined number of individual management cells within a period T. If the transmission cycle does not allow an error width, a method similar to the case of the common management cell described above may be used. That is, all cells other than the individual management cell to be sent are made to wait, or if they are empty cells, they are discarded and the individual management cell to be sent is sent with the highest priority. However, it is preferable to send the main signal cell without waiting because it does not disturb the traffic. A configuration for implementing this method is shown in FIG. This configuration tries to send individual management cells instead of empty cells as much as possible, but when it is expected that a predetermined number cannot be sent within the period T while waiting for empty cells, the individual management cell is made to wait for the main signal cell. Is transmitted, the mechanism is different from the mechanism in which the common management cell is always transmitted with the highest priority in the accurate cycle T.

The configuration of the downlink dedicated management cell transmission mechanism will be specifically described with reference to FIG. Here, the configuration shown in FIG. 13 is a configuration in which a downlink dedicated management cell is generated for one slave device. The cycle T generation counter 6 notifies the individual management cell generation management unit 25 of the accurate cycle T. The individual management cell generation management unit 25 issues a generation instruction to the individual cell generation unit 22 when the slave device is not stopped. As a result, the individual management cell generation unit 22 generates a predetermined number of individual management cells and sends them to the management cell buffer 24. Of course, the functions of the generation management unit 25 and the generation unit 22 may be realized in one unit. actually,
Since the function of the generation management unit 25 is relatively simple, it is realistic to take it into the generation unit 22.

The management cell buffer 24 notifies the individual management cell transmission control section 20 of the presence / absence of cells to be transmitted. As shown in FIG. 14, the individual management cell transmission control unit 20 has an individual management cell to be transmitted in the management cell buffer 24, and the empty cell detection unit 21 is empty in the cell string output from the ATM-SW 102. When a cell is detected, a notification that there is an empty cell is given, and when receiving the notification, the management cell buffer 24 issues an individual management cell transmission instruction and the management cell insertion unit 23 issues a management cell insertion instruction. Then, the empty cells mixed with the main signal cells and the individual management cells are exchanged and transmitted to the electro-optical converter 5.

The cell coming from the ATM-SW 102 is an ATM
Therefore, an empty cell can be expected stochastically, and an empty cell can be expected with a high probability if there is a margin in the contracted band of the main signal. However, when it is expected that the required number of individual management cells cannot be transmitted within the cycle T by waiting for an empty cell, a cell standby instruction is issued to the cell buffer 2 and the individual management cell is forcibly transmitted with the highest priority. However, since the common management cell has the highest priority in order to notify the accurate cycle T,
The dedicated management cell needs to be transmitted before the common management cell indicating the next cycle T.

Here, a more detailed operation of the individual management cell transmission control section 20 will be described. In particular, a specific determination method of the "forced transmission required" determination shown in FIG. 14 will be described. In order to send a predetermined number of individual management cells within a fixed period,
The dedicated management cell generation unit 22 or the dedicated management cell generation management unit 25 grasps how many downlink dedicated management cells should be transmitted within the next cycle T. Individual management cell transmission control unit 20
(A) grasps how many downlink dedicated management cells have already been transmitted within the current cycle and (b) how many are not yet transmitted by the remaining cell notification or by an internal counter. Also,
(C) How many cell time slots are left in the current cycle, and (d) When the transmission timing of the common management cell is sequentially grasped, and management is performed when the notification of the empty cell is received from the empty cell detection unit 21. When an individual management cell to be sent to the cell buffer 24 remains, that individual management cell, that is,
The downlink dedicated management cell is transmitted.

When there are remaining dedicated management cells to be transmitted up to the end of the cycle T, the downlink dedicated management cells are re-selected for other cells in order to send the specified number of downlink dedicated management cells within the cycle. The individual management cell transmission control unit 20 operates to transmit with priority. However, the common management cell has a higher priority and must not be kept waiting. Therefore, the transmission timing of the common management cell is also controlled by the individual management cell transmission control unit 2
0 manages. At that time, if there is a main signal cell to be transmitted at the same time, the cell buffer 2 is instructed to wait. The cell buffer 2 may be replaced with an output buffer or an input buffer inside the ATM-SW 102.

Therefore, in this configuration, it is not specified in which position within the cycle T the individual management cell is transmitted. For example, it may be sent at the beginning of the cycle T or at the end. On the contrary, it is easier to define a time slot to be sent to a specific time slot within the cycle T.
For example, a series of individual management cells are continuously sent to the common management cell. In the meantime, the main signal cell may be retained in the cell buffer 2, and the transmission of the main signal cell may be started after the transmission of all the individual management cells to be transmitted in the current cycle T is completed.

However, this distorts the time-discrete characteristic of the main signal cell, and therefore should not be performed as much as possible.
In other words, distorting means that the transmission pattern of the main signal cell is made to wait for each cycle T, and the CDV (cell delay variation) is changed. Therefore, the common management cell needs to be forcibly transmitted in order to send the accurate cycle T, but the individual management cell should not be forcibly transmitted as much as possible and should be replaced with an empty cell as much as possible. From this point of view, the configuration of this embodiment is useful and effective. As a compromise between the two, it is possible to arrange the downlink dedicated management cells in the frame at equal intervals. In this case, since the location of the downlink dedicated management cell is clear, detection and signal processing can be performed relatively easily, and the influence on the CDV of the main signal is small. The specific configuration is similar to that of FIG. 13, and the individual management cell transmission control unit 20 issues management cell insertion instructions at equal intervals.

In FIG. 13, the empty cell detector 21 is
The cell buffer 2 is connected to the cell buffer 2. However, since the cell to be output next is waiting at the head of the cell buffer 2, the cell buffer 2 is integrated with the cell buffer 2 instead of separately providing an empty cell detection unit. This is because it is determined that it is realistic that the above-mentioned function does not change even if the empty cell detection unit 21 is inserted between the cell buffer 2 and the management cell insertion unit 23. .

[Eighth Embodiment] Next, based on the seventh embodiment, an individual management cell generation unit 2 corresponding to a plurality of slave devices is provided.
FIG. 15 shows a configuration having 2-1 to N. The basic operation of the configuration of this embodiment follows the operation of the configuration of the seventh embodiment. This configuration is a configuration in which a compulsory transmission function is added to the function of the configuration shown in FIG. 12, and the operation of the individual management cell transmission control unit 20 is somewhat complicated.

The cycle T generation counter 6 notifies the individual management cell generation management section 25 and the individual management cell transmission control section 20 of an accurate notification of the cycle T. Individual management cell generation management unit 2
In 5, the cell generation instruction is issued to the individual management cell generation units 22-1 to 22-N prepared for each slave device based on the operation shown in FIG. When receiving the cell generation instruction, each of the individual management cell generation units 22-1 to 22-N generates a predetermined number of individual management cells in which the destinations of the reception-waiting slave devices to be transmitted and their contents are placed in the PDS cells. Then, it is passed to the PDS cell multiplexer 26.

The PDS cell multiplexer 26, which operates in the same manner as ATM multiplexing, performs cell multiplexing according to the prior art and notifies the number of significant cells. The individual management cell transmission control unit 20 uses the individual management cell generation unit 22-1.
To N for each individual management cell, a determination is made for each slave device based on the operation shown in FIG.
The S cell multiplexing unit 26 is instructed to transmit the individual management cell, the management cell insertion unit 23 is transmitted to transmit the management cell, and the individual management cell is transmitted.

In particular, when it can be predicted that a predetermined number of individual management cells cannot be sent and remain in the cycle T while waiting for an unspecified occurrence of empty cells, the individual management cell transmission is performed. The control unit 20 determines that the forced transmission is necessary, and causes the cell buffer 2 to wait for the main signal cell and transmits the individual management cell. Here, as described in the sixth embodiment, the PDS cell multiplexer 26 in FIG.
Can be replaced with a buffer provided corresponding to each output of the individual management cell generation units 22-1 to 22-N.

[Ninth Embodiment] In the present embodiment, the structure of a mechanism capable of transmitting both the common management cell and the downlink dedicated management cell described above will be described. Such a combination of mechanisms is used in the common management cell transmission mechanism described in the first to third embodiments and the downlink dedicated management cell transmission mechanism described in the fifth to eighth embodiments.
Any combination is possible, but in that case, the common management cell should be transmitted with priority, and the management cell inserting unit 4 for inserting the common management cell into the main signal cell inserts the downlink dedicated management cell. It is arranged on the output side of the management cell insertion unit 23, or each individual management cell transmission control unit is set to control so that the downlink individual management cell is not transmitted to the slave device while the common management cell is transmitted. There is a need to.

In the present embodiment, the configuration of the transmission mechanism of the common management cell shown in FIG. 1 and the configuration of the transmission mechanism of the downlink individual management cell shown in FIG. 13 are combined, and the common management cell and the individual management cell have the same management. A case where the cell is inserted into the cell by the insertion section will be described. Hereinafter, description will be given with reference to FIGS. 16 and 17. In this figure, portions corresponding to the respective portions in FIGS. 1 and 13 are designated by the same reference numerals, and the description thereof will be omitted.

The configuration of this embodiment is basically as follows.
The configuration has both the configurations of FIG. 1 and FIG. 13. That is, the ATM-SW 102, the cell buffer 2, the electro-optical converter 5, the cycle T counter 6, and the empty cell detection unit 21 described above.
In addition, it has a common management cell generation unit 7 and an individual management cell generation unit 22, and management cell buffers 9 and 24 for holding the common management cell and the individual management cell output from these generation units, respectively. In addition, the management cell insertion unit 51
Has a three-input-one-output configuration, and the three input ends are connected to the output ends of the PDS cell header addition unit 3, the management cell buffers 9 and 24, respectively. Further, it is assumed that the individual management cell generation unit 22 in FIG. 16 has the function of the individual management cell generation management unit 25 in FIG.

Further, the common / individual management cell transmission control unit 50
According to the determination method shown in FIG.
Switching control. That is, the main signal cell transmitted from the in-office interface unit (not shown) and passed through the ATM-SW 102 flows to the PDS cell header addition unit 3 via the cell buffer 2 to which the PDS header is added, and in the management cell insertion unit 51, If the changeover switch is connected to the upper side in the figure, it passes through the electro-optical converter (E / O) 5 and is finally sent out to an optical fiber connected to a plurality of slave devices.

On the other hand, the cycle T generation counter 6 generates accurate cycle T information, and the common management cell generator 7,
The individual management cell generation unit 22 and the common / individual management cell transmission control unit 50 are notified. As a result, the common management cell generation unit 7 generates a predetermined number of common management cells each time the notification of the period T is received, and the individual management cell generation unit 22.
Generates a predetermined number of individual management cells when the slave device is not stopped when the cycle T notification is received.

The common / individual management cell transmission control unit 5
0 is the timing to send the common management cell,
Alternatively, when approaching, even if the individual management cell remains in the management cell buffer 24 or the individual management cell needs to be forcibly transmitted, a management cell transmission instruction is issued to the management cell buffer 9, and the management cell inserting unit 4 The common management cell insertion instruction is issued to. At this time, when there is no notification from the empty cell detection unit 21 that there is an empty cell, a cell standby instruction is issued to the cell buffer 2 and the common management cell is preferentially transmitted.

Upon receiving these instructions, the management cell buffer 9 outputs one common management cell, and the management cell inserting section 51
Switch the switch to the center of the figure to switch the management cell buffer 9
Send the common management cell coming from the to the electro-optical converter 5. Further, the common / individual management cell transmission control unit 50 also issues an instruction to the cell buffer 2. This instruction is a cell standby instruction,
Make the main signal cell wait for the required period. Further, the common / individual management cell transmission control unit 50 determines the content shown in FIG. 14 when it is not time to transmit the common management cell or when it is not approaching.

That is, when an individual management cell is generated from the individual management cell generator 22 and sent to the management cell buffer 24, the management cell buffer 24 determines whether or not there is a cell to be transmitted by the common / individual management cell transmission controller. Notify 50. The individual management cell to be transmitted is the management cell buffer 24.
When the empty cell detection unit 21 notifies that there is an empty cell, the common / individual management cell transmission control unit 50 instructs the management cell buffer 24 to transmit an individual management cell and the management cell insertion unit 51 to the management cell insertion unit 51. Issue an individual management cell insertion instruction. As a result, the management cell insertion unit 51 switches the switch to the lower side in the figure, and sends the individual management cell instead of the empty cell to the electro-optical converter 5.

The common / individual management cell transmission control unit 50
Determines whether "forced transmission is required". That is,
The common / individual management cell transmission control unit 50 determines (a) how many downlink individual management cells have already been transmitted in the current cycle, and (b) how many are not yet transmitted by the remaining cell notification, or The empty cell detection unit 2 grasps by an internal counter, and sequentially grasps (c) how many cell time slots are left in the current cycle and (d) when the common management cell is sent out.
When the notification of the presence of an empty cell is received from 1, if there is an individual management cell to be sent to the management cell buffer 24, the individual management cell, that is, the downlink dedicated management cell is sent.

As described above, in the structure of the transmission mechanism of various management cells shown in FIG. 16, the common management cell is transmitted again with priority, and in other cases, the presence or absence of the individual management cell, the necessity of forced transmission, and , An individual management cell is transmitted depending on the presence / absence of an empty cell. That is, when the cell coming from the ATM-SW 102 is kept waiting, it is temporarily stored in the cell buffer 2,
It is sent after sending the common management cell. In addition, ATM-SW1
If the cell from 02 is an empty cell, it may be discarded without being reserved. Also, instead of providing the cell buffer 2, A
The output buffer or the input buffer of the TM-SW 102 may be provided with a mechanism for receiving an instruction for stopping the cell transmission, and the functions of the cell buffer 2 may be realized by these buffers.

[Tenth Embodiment] Next, the configuration of a mechanism for receiving a downlink dedicated management cell by a slave device will be described. The downlink common management cell described above is under control, that is, contains the contents necessary for all slave devices connected to a specific transmission path interface in the master device, so all slave devices receive and Take in. However, since the downlink dedicated management cell is a cell for transferring information regarding a specific slave device, it is necessary to discard the slave device that does not correspond. The slave device identification number necessary for determining whether or not this is applicable can be identified by looking at the DID (destination ID) shown in FIG. For example, if the main device indicates that the ID of the self-subordinate device is # 3, the downlink dedicated management cells other than DID = 3 are discarded.

FIG. 18 shows a configuration for performing cell reception / discard determination of the device according to FIG. In this figure, components corresponding to those in the configuration shown in FIG. 7 are designated by the same reference numerals, and their description will be omitted. The slave device stores the self-slave device number = DID given from the main device in the startup operation in the DID storage memory 30. After that, D of all received downlink PDS cells
The DID comparison unit 31 compares the ID with the contents of the DID storage memory 30. If they do not match, the cell discard switch 32 is instructed to discard them. Here, the compensating delay unit 33 uses the DI
The cell output from the reception processing unit 11 is delayed by the time required for the comparison processing in the D comparison unit 31.
It is provided to match the timing of the input of the cell to be discarded to the cell discard switch 32 and the discard instruction issued to the DID comparison unit 31.

[Eleventh Embodiment] In the present embodiment, the configuration of a transmission mechanism of an upstream individual management cell in a slave device will be described. The uplink individual management cell is defined for each slave device and is an individual management cell transmitted from each slave device to the master device, and transfers information related to warnings such as signal disconnection due to downlink signals and in-service bit error monitoring. . Also, sending out this cell itself becomes the monitoring information. This in-service bit error monitoring will be described later in detail. There are three possible methods for generating the uplink dedicated management cell.

(1) A method of generating as needed, and making the cycle and the generation interval arbitrary. In this case, when there is no upstream main signal cell, that is, the uplink dedicated management cell can be transmitted instead of transmitting an empty cell. The uplink individual management cell may be generated immediately before transmission, or may be created in advance and accommodated in the management cell buffer. The former case has the cycle T counter 6 removed from FIG. 8, and the latter case has the cycle T counter removed from FIG. (2) Similar to the conventional ATM cell, the average individual management cell generation cycle is defined based on the cycle notification output from the cycle T generation counter 6, but an error is allowed in it. . The specific configuration is the same as in (1). When the uplink individual management cell is generated immediately before the transmission, the configuration is such that the cycle T counter 6 is removed from FIG. 8 and is created in advance and accommodated in the management cell buffer. The configuration is similar to that of FIG. 9 except that the cycle T counter is removed. There are the following two factors that cause cell delay in the PDS transmission method. (A) Delay until finding an empty cell. This is the fate of ATM multiplex and is a probabilistic delay time. (B) Delay until transmission permission comes from the main device. This is a delay unique to the PDS transmission system. This is a trade-off for sharing a master device by a plurality of slave devices. (3) A method of accurately transmitting a predetermined number of uplink individual management cells within this period, assuming that the common management cell transferred from the main device is exactly periodic.

FIG. 19 shows a specific configuration of the uplink dedicated management cell transmission mechanism. First, the configuration unique to the slave device for the PDS transmission system will be described. The reception processing unit 11, the PDS cell header adding unit 39, and the fixed delay unit 41 in FIG.

The reception processing section 11 outputs a transmission permission arrival notification. This is the PD described in FIG.
This is the basic operation of the S transmission method. The PDS cell header adding section 39 attaches an appropriate PDS cell header to the main signal cell. The fixed delay unit 41 is also the basic operation of the PDS described in FIG. That is, the distance between the master device and the slave device, that is, the delay amount is directly obtained only when the slave device is activated. The upstream PDS cell is the main device reception point,
Each slave device is instructed to the fixed delay section 41 at the time of start-up so as to come to the just specified time position by the fixed delay time dk to be delayed. Therefore, actual transmission is performed after the delay time instructed after the transmission permission arrives.
It is a mechanism that realizes the delay.

Next, the structure of the entire mechanism for generating and transmitting the individual management cell will be described. From the cycle T counter 14,
The notification of the cycle T is notified to the individual management cell generation unit 35, whereby the individual management cell to be transmitted within the cycle T is generated and accumulated in the management cell buffer 36. On the other hand, the reception processing unit 11 extracts the transmission permission arrival notification given to the slave device from the downlink PDS cells, and notifies the determination unit 37 of the transmission permission arrival notification. The determination unit 37 determines whether or not the transmission timing limit of the individual management cell has been reached when the transmission permission is received, and the cell wait notification is notified from the main signal cell buffer 38 and the management cell buffer 36, respectively. Based on this, the judgment shown in FIG. 20 is made. That is, the main signal cell buffer 38
Alternatively, the transmission instruction is given to one of the management cell buffers 36, and the management cell insertion unit 40 is selectively controlled so that the cells in the buffer to which the transmission instruction is given are finally transmitted to the main device.

For example, when a main signal transmission instruction is given to the main signal cell buffer 38, the changeover switch of the management cell insertion unit 40 is switched to the upper side in the figure and P
The DS cell header adding unit 39 adds the PDS cell header to the main signal cell, the management cell inserting unit 40, and the fixed delay unit 41 delays the fixed delay time dk.
The DS cell is sent to the main device. The phase of the cycle T generation counter 14 and the delay value of the fixed delay unit 41 are
It is set at startup. (4) As a special case of (3) above, the main device specifies a time slot into which an uplink dedicated management cell is inserted. In this method, the slave device transmits the uplink dedicated management cell based on the uplink dedicated management cell transmission command from the master device regardless of the presence or absence of the cell of the main signal as in the common management cell. As a method of designating a cell to be transmitted in the uplink direction as an individual management cell, for example, after receiving the downlink individual management cell, the uplink individual management cell is output when the next PID addressed to the own device is received. The specific configuration is the same as in FIG.
However, if the judgment unit 37 judges that the main device has ordered the transmission of the individual management cell, the next cell is programmed to output the individual management cell.

[Twelfth Embodiment] In this embodiment, a mechanism for monitoring the upstream or downstream signal described at the beginning of the eleventh embodiment will be described. The transmission mechanism of various management cells described so far transmits a predetermined number of common management cells, downlink dedicated management cells, and uplink dedicated management cells during the period T, so that such monitoring can be realized. In other words, (1) If the predetermined number cannot be received during the period T in the master device or the slave device, it is possible to determine that an abnormality has occurred and issue an alarm. The specific configuration is the same as in FIG. 7. This is an example of the case where the slave device monitors the cycle T by taking the common management cell as an example. However, the number of downlink dedicated management cells or the number of uplink dedicated management cells that should be transmitted during the cycle T is the reception side. If known, the cell loss or the extra cell can be detected. The configuration shown in FIG. 21 may be provided in the main device or the slave device, or in both of them, and in various management cell arrival number confirmation units 43, when provided in the main device, provided in the slave device of the uplink individual management cell. If the number of common management cells or downlink dedicated management cells is checked, the extra arrival notification is reported if the number is larger than a predetermined number, and the cell loss occurrence notification is reported to the alarm processing unit 44 if the number is smaller than a predetermined number. Shows.

(2) The in-service bit error can be monitored by the coincidence between the result calculated by the sending side and the result calculated again by the receiving side by always performing the BIP calculation. The BIP calculation itself is performed in the SDH frame as a known technique. Therefore, if it is realized by a configuration unique to the PDS transmission system with reference to this, the number of cells in the upstream direction depends on the band allocated to the slave device. Although the number of permitted transmissions changes, if there is a fixed rule in the number of permitted cells or in the period T, interleaving may be performed in units of the number of bytes in accordance with this. The BIP calculation result can be notified every cycle T if it is placed in the common management cell in the case of a downlink signal and in the uplink dedicated management cell in the case of an uplink signal.

[Thirteenth Embodiment] In this embodiment, a method and a configuration for notifying the information of the cycle T when a plurality of common or individual management cells are transmitted within the cycle T will be specifically described. When the common notification content to be notified to all slave devices cannot be installed in one common management cell, it is necessary to use a plurality of common management cells. If the number of common management cells to be transmitted in this period T is M,
Even if M pieces are sent, the cycle T needs to be accurately notified to each slave, and therefore one of them has a function of notifying the cycle T to all slaves. There are several methods for providing one of the M common management cells with the period T notification function.

(1) The first one of M pieces is provided with the period T notification function. Since it is necessary to distinguish from other common management cells, the PDS header or PD of the common management cell
A cycle T notification identification bit is defined in the S cell payload to have a meaning of whether or not it is the first common management cell. The slave device recognizes that the cycle T notification has been received when the cycle T notification identification bit has the content indicating that it is the cycle T notification cell among the received common management cells. No matter how many times the common management cell identified as not the head comes, the circuit for identifying the cycle T is not affected.

More specifically, the same method as that used for identifying the cell type in FIG. 2 can be considered. That is, as shown in FIG. 22, PDS cell header or PDS
A cell identification bit b3 for period T notification is newly defined in the cell payload, and using this, information as to whether or not the cell is a period T notification cell may be placed. Only in the case of the common management cell, that is, in the example of FIG. 2, only when b1 = 0 and b2 = 1, it is sufficient to represent the type of the period T or not by b3. That is, when b1 and b2 are other than 0 and 1, respectively, the cycle T notification cell identification bit b3 may have a different meaning.

(2) A notification method different from the above-described cell identification bit for notification of period T will be described. PDS of common management cell
Although defining the identification bit in the header is the same, it has the meaning of "presence / absence of another common management cell in the current cycle T". The slave device that has received the determination makes that determination. Upon receipt of the scheduled, it can be seen that the next common management cell is independent of period T. When the unscheduled message is received, it can be predicted that the next common management cell is for notifying the period T before the corresponding cell arrives. As long as there is a schedule, the circuit that identifies the cycle T is not affected.

(3) Set the common management cell for notifying the cycle T to 1
Although it is possible in principle not to be the second, the period T
There is no merit considering that it is necessary to accurately transmit the common management cell for notifying that the period is T, and that it is necessary to transmit at least one common management cell before that.

In the above methods (1) and (2), especially 2
There is no restriction on the position of the common management cell after the cell eye, and there is no restriction on the number of the common management cells with respect to the cycle T identification. It goes without saying that the number of main signal cells is not long enough to wait for the common control cell to be sent.

[Fourteenth Embodiment] In this embodiment, a method and a configuration for notifying the number information of the individual management cells transmitted within the cycle T will be specifically described. before that,
In the fifth and seventh embodiments, it is explained that the individual management cell generation unit generates a predetermined number of individual management cells within the cycle T according to an instruction from the individual management cell generation management unit. The "predetermined number" will be described in detail. The “predetermined number” may be a constant number over the entire period T, or may be different for each period as long as it can be reliably expected on the receiving side. For example, considering the amount of information to be sent, it is wasteful to send two individual management cells for each cycle T because the utilization rate of the payload in the cell is low, but one for each individual cell that cannot be sent. It is also possible to minimize useless cells by sending the cells alternately. Alternatively, the procedure may be such that one dedicated management cell is always sent in each cycle T, and one or more individual management cells are sent when a signal indicating continuation is included in the one cell as needed.

FIG. 23 shows a method of informing the slave device of whether the common or individual management cell transmitted within the period T is the last in this cell. For example, a final common management cell identification bit b4 is provided in each common management cell, and if the common management cell can no longer be sent in the current cycle T, then b4 = 0 of the last common management cell is sent to the slave device. To do. The slave device, which has received, sees b4 = 0 in the common management cell, and finds that the next cycle is a new cycle T.

Further, if the first common management cell is determined to be the cycle T notification cell described in the thirteenth embodiment within the cycle T, the final common management cell identification bit b4 of the received common management cell is 0. If it is, it is known in advance that the next common management cell is for notification of the cycle T. At this time, if a common management cell that does not notify the cycle T arrives before entering a new cycle T, it can be understood that the abnormal operation occurs.

On the contrary, if b4 = 1, it can be expected that the common management cell will still come before the period T ends.
Therefore, it can be seen that the next common management cell is not for notification of the cycle T. Regarding the individual management cell, the final individual management cell identification bit b4 is provided separately from the common management cell,
By looking at b4, it informs the slave device whether or not the next individual management cell will come within the period T, and the slave device can judge by looking at b4. By adopting this method, the master device can notify the slave device of the number of cells to be transmitted within the cycle T.

[0106]

[0107]

[0108]

As described above, according to the first aspect of the invention, the master device transmits the downlink individual management cell for notifying each slave device of the management information regarding each of the plurality of slave devices, Since each of the slaves selects and receives the downlink dedicated management cell addressed to itself, not only can the management information regarding each slave be communicated, but each slave can determine the predetermined management within one frame period. If some downlink dedicated management cells cannot be received, it can be considered that some kind of transmission path abnormality has occurred. The main device is
When the generated individual management cell is temporarily stored in the individual management cell buffer and it is detected that an empty cell is output, the individual management cell is sent instead of the empty cell, so the number of cells to be sent does not increase. An individual management cell can be transmitted and received between the device and the slave device, and the PDS transmission path can be efficiently used. Further, after the main device and each of the plurality of slave devices recognize the frame period, the number of individual management cells accommodated in the individual management cell buffer is transmitted by the time the frame period in which the individual management cell occurs ends. When the number of possible PDS cells becomes equal, cells other than empty cells are temporarily accommodated in the information cell buffer, and all PDS cells to be transmitted in the remaining time of the frame cycle are set as individual management cells. It is possible to reliably insert a predetermined number of individual management cells into the. This allows
When the reception side of the individual management cell cannot receive the predetermined number of individual management cells in one frame synchronization, it can be considered that the device that has transmitted the individual management cell has an abnormality.

According to the invention of claim 2 ,
Each of the plurality of slave devices transmits an uplink individual management cell for notifying the main device of management information about each self-slave device at the timing instructed by the main device, while the main device receives the uplink individual management cell. Therefore, the master device can individually recognize the management information regarding a specific slave device and an external device connected to the slave device. Further, each slave device temporarily stores the generated individual management cell in the individual management cell buffer, and when detecting that an empty cell is output, the individual management cell is transmitted in place of the empty cell. The occurrence of the individual management cell and the replacement of the generated individual management cell and the empty cell can be performed individually regardless of the detection of
The control for sending the individual management cell becomes easy. Further, after the main device and each of the plurality of slave devices recognize the frame period, the number of individual management cells accommodated in the individual management cell buffer is transmitted by the time the frame period in which the individual management cell occurs ends. When the number of possible PDS cells becomes equal, cells other than the empty cells are temporarily accommodated in the information cell buffer, and are transmitted in the remaining time of the frame period.
Since all the S cells are used as individual management cells, it is possible to reliably insert a predetermined number of individual management cells within one frame period. As a result, if the reception side of the individual management cell cannot receive the predetermined number of individual management cells in one frame synchronization, it is considered that an error has occurred in the device that transmitted the individual management cell. You can

According to the invention of claim 3 ,
The position of the downlink dedicated management cell in the frame is clarified in advance, and detection of the downlink dedicated management cell and signal processing on the slave device side can be facilitated.

[0111]

[0112]

[0113]

[0114]

[0115]

According to the invention of claim 4 ,
The position of the downlink dedicated management cell in the frame is clarified in advance, which facilitates detection of the downlink dedicated management cell and signal processing on the slave side, and also has an effect on CDV (cell delay variation) of the main signal. Becomes smaller.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a common management cell transmission mechanism in first and second embodiments of the present invention.

FIG. 2 is an explanatory diagram for explaining a position of a cell type recognition bit provided in a PDS cell in the same embodiment.

FIG. 3 is an explanatory diagram for explaining transmission timings of various cells in the same embodiment.

4 is an explanatory diagram for explaining operation contents of a common management cell transmission control unit in the transmission mechanism shown in FIG.

FIG. 5 is a block diagram showing a configuration of a common management cell transmission mechanism according to a third embodiment of the present invention.

6 is an explanatory diagram for explaining an operation content of a common management cell transmission control unit in the transmission mechanism shown in FIG.

FIG. 7 is a block diagram showing a configuration of a common management cell receiving mechanism according to a fourth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a downlink dedicated management cell transmission mechanism for one slave device according to a fifth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a downlink dedicated management cell transmission mechanism different from the configuration of FIG. 8 in the same embodiment.

10 is an explanatory diagram for explaining an operation content of an individual management cell generation management unit in the transmission mechanism shown in FIG.

11 is an explanatory diagram for explaining an operation content of an individual management cell transmission control unit in the transmission mechanism shown in FIG.

FIG. 12 is a block diagram showing a configuration of a downlink dedicated management cell transmission mechanism for a large number of slave devices based on the transmission mechanism shown in FIG. 9 in the sixth embodiment of the present invention.

FIG. 13 is a block diagram showing a configuration having an empty cell insertion and individual management cell forced transmission function in a downlink individual management cell transmission mechanism for one slave device according to a seventh embodiment of the present invention.

FIG. 14 is an explanatory diagram for explaining the operation content of the individual management cell transmission control unit in the transmission mechanism shown in FIG.

FIG. 15 shows an eighth embodiment of the present invention.
It is a block diagram which shows the structure of the downlink individual management cell transmission mechanism with respect to many slave devices based on the transmission mechanism shown in FIG.

FIG. 16 is a block diagram showing the configuration of a delivery mechanism that also serves as the delivery mechanism shown in FIGS. 1 and 13 in a ninth embodiment of the present invention.

17 is an explanatory diagram for explaining the operation content of a common / individual managed cell transmission control unit in the transmission mechanism shown in FIG.

FIG. 18 is a block diagram showing a configuration of a non-corresponding cell discard mechanism associated with reception of a downlink dedicated management cell according to the tenth embodiment of the present invention.

FIG. 19 is a block diagram showing the configuration of an uplink individual management cell transmission mechanism in the eleventh embodiment of the present invention.

FIG. 20 is an explanatory diagram for explaining the operation content of the determination unit in the sending mechanism shown in FIG. 19.

FIG. 21 is a block diagram showing a configuration of a cell loss or extra cell arrival alarm detection mechanism in a master / slave unit in a twelfth embodiment of the present invention.

FIG. 22 is a PDS in a thirteenth embodiment of the present invention.
It is explanatory drawing for demonstrating the position of the cell type recognition bit for period T notification provided in the cell.

FIG. 23 is a PDS in a fourteenth embodiment of the present invention.
It is an explanatory view for explaining the position of the final common / individual management cell recognition bit provided in the cell.

FIG. 24 is an explanatory diagram for explaining a configuration of a main device and a slave device and a connection state between the main device and the slave device in a conventional PDS transmission system.

FIG. 25 is an explanatory diagram illustrating a configuration of a PDS cell in a conventional PDS transmission method.

FIG. 26: Various PDSs in the conventional PDS transmission system
It is explanatory drawing for demonstrating the timing of a cell.

[Explanation of symbols]

2 ... Cell buffer, 3, 39 ... PDS cell header addition unit, 4, 23, 40, 51 ... Managed cell insertion unit, 5,
42 ... Electro-optical converter, 6, 14 ... Cycle T generation counter, 7 ... Common management cell generation unit, 8 ... Common management cell transmission control unit, 9, 24, 36 ... Management cell buffer, 1
0 ... Optical-electric conversion unit, 11 ... Reception processing unit, 11a ...
... bit synchronization unit, 11b ... cell synchronization unit, 11c ... cell type recognition unit, 12 ... internal circuit, 13 ... common management cell arrival period confirmation unit, 15, 44 ... alarm processing unit, 20 ...
... Individual management cell transmission control unit, 21 ... Empty cell detection unit, 2
2 ... Individual management cell generation unit, 25 ... Individual management cell generation management unit, 26 ... PDS cell multiplexing unit, 30 ... DID storage memory, 31 ... DID comparison unit, 32 ... Cell discard switch, 33 ... Compensation delay unit, 35 ... Individual management cell generation unit, 37 ... Judgment unit, 38 ... Main signal cell buffer, 41 ... Fixed delay unit, 43 ... Various management cell arrival number confirmation unit, 50 ... Common / individual management cell transmission control unit.

─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Yoshiro Takigawa 3-19-3 Nishishinjuku, Shinjuku-ku, Tokyo Inside Nippon Telegraph and Telephone Corporation (72) Kenji Nakanishi 3-chome, Nishishinjuku, Shinjuku-ku, Tokyo 19 No. 2 Nihon Telegraph and Telephone Corporation (56) Reference JP-A-5-336143 (JP, A) JP-A-8-163168 (JP, A) 1991 IEICE Autumn Meeting B-477 1994 IEICE Spring Conference B-829 IEICE Technical Report CS94-28 1992 IEICE Spring Conference B-729 1993 IEICE Fall Conference B-668 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/44 H04L 12/56

Claims (4)

(57) [Claims] 1. A PDS transmission system in which one main device and a plurality of slave devices are connected in a star shape, and information is transmitted in cell units between the main device and each of the slave devices. The device transmits a downlink individual management cell that notifies the slave device of management information about each slave device, and each slave device selects and receives the downlink individual management cell addressed to itself.
In the DS transmission method, the main device includes an empty cell detection unit that detects an output of an empty cell, and an individual management cell transmission control unit that instructs generation and insertion of an individual management cell based on a detection result of the empty cell detection unit. An individual management cell generating unit that generates an individual management cell based on an instruction to generate the individual management cell by the individual management cell transmission control unit and stores the individual management cell in a buffer for the individual management cell; and an individual management cell by the individual management cell transmission control unit. An individual management cell inserting section that inserts an individual management cell generated in the individual management cell generating section in place of the empty cell based on the insertion instruction of, and sends the individual management cell to the slave device. When the number of individual management cells accommodated in the buffer becomes equal to the number of PDS cells that can be transmitted by the end of the frame period in which the individual management cells occur. , Once housed in the information cell buffer cell non-empty cell, and sends the remaining time of the frame period PD
PD characterized by using all S cells as individual management cells
S transmission method. 2. A PDS transmission system in which one main device and a plurality of slave devices are connected in a star shape and information is transmitted in cell units between the main device and each of the slave devices. In the PDS transmission method in which the slave device transmits an uplink individual management cell notifying the master device of management information about the slave device to the master device, and the master device receives the uplink individual management cell, each slave device is An empty cell detection unit that detects an output of an empty cell; an individual management cell transmission control unit that instructs generation and insertion of an individual management cell based on the detection result of the empty cell detection unit; and an individual management cell transmission control unit Based on an individual management cell generation unit that generates an individual management cell based on an individual management cell generation instruction and stores it in the individual management cell buffer, and an individual management cell insertion instruction from the individual management cell transmission control unit. An individual management cell inserting section for inserting the individual management cell generated in the individual management cell generating section in place of the empty cell and transmitting it to the main device, and is accommodated in the individual management cell buffer. When the number of individual management cells becomes equal to the number of PDS cells that can be transmitted by the end of the frame cycle in which the individual management cells occur, cells other than empty cells are temporarily accommodated in the information cell buffer and PD to be sent in the remaining time
PD characterized by using all S cells as individual management cells
S transmission method. 3. A PDS transmission system in which one master device and a plurality of slave devices are connected in a star shape, and information is transmitted in cell units between the master device and each slave device. The device transmits a downlink individual management cell that notifies the slave device of management information about each slave device, and each slave device selects and receives the downlink individual management cell addressed to itself.
In the DS transmission method, the main device recognizes how many downlink dedicated management cells have already been transmitted and how many individual management cells have not been transmitted within the current frame period, and within the current frame period. Has a grasping means for grasping the number of remaining cell time slots, the timing of transmitting the downlink dedicated management cell is specified within a frame period, and the transmission is performed at the timing of transmitting the downlink dedicated management cell. When the scheduled cell is an empty cell, the empty dedicated cell is replaced and the downlink dedicated management cell is transmitted to the slave device. When the cell scheduled to be transmitted at the timing is an information cell other than the empty cell, the grasping means A PDS transmission system characterized in that the information cell is temporarily accommodated in an information cell buffer based on the grasped result, and the downlink dedicated management cell is transmitted to the slave device. 4. The PDS transmission method according to claim 3 , wherein the main unit transmits the downlink dedicated management cells at equal time intervals within a time region in which the downlink dedicated management cells can be transmitted. PDS transmission method characterized by.