JP3569128B2 - Cell transmission control method for ATM communication system - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention connects a center node device accommodating a host terminal and a node device accommodating one or a plurality of remote terminals via a communication line, and transmits a request from the host terminal to each remote terminal accommodated in the node device. The present invention relates to an ATM (Asynchronous Transfer Mode) communication system for collecting data, and more particularly to a cell of an ATM communication system in which a node device controls transmission of data from a remote terminal in response to a transmission request from a host terminal in accordance with an activation signal from the remote terminal. It relates to a transmission control method.
[0002]
[Prior art]
As an example of a communication system using the ATM technology, a center node device accommodating a host terminal and a node device accommodating one or a plurality of remote terminals are connected by a communication line, and the node device is transmitted to the node device by a transmission request from the host terminal. There is an ATM communication system that collects data from each accommodated remote terminal.
[0003]
FIG. 8 shows the configuration of this conventional ATM communication system.
[0004]
As shown in FIG. 8, in a conventional ATM communication system, a center switch node device 200 that accommodates a host terminal 100 and a switch node device 400 that accommodates a local terminal 300 are connected via a communication path 5, and A branch device 600 is provided between the center switch node device 100 and the center switch node device 200. Here, the switch node device 200 performs processing of ATM adaptation layer type 1 (AAL1).
[0005]
[Problems to be solved by the invention]
In the above-described conventional configuration, when polling the data of each local terminal 300 from the host terminal 100, it is necessary to set each VC (virtual channel) point-to-point as shown in FIG. This is because the AAL1 format cell is normally in a communication state (notifying a silence state) because it handles voice transmission and the like, whereas there is a function for controlling the cell transmission in response to a request from a local terminal. Because there was not.
[0006]
In such a configuration, an AC branching device is required between the host terminal and the communication device. In addition, there is a possibility that traffic in the network will increase due to the necessity of connecting points.
[0007]
Therefore, the present invention solves the above-described problem, and can perform communication with the same transmission capacity as when a host terminal communicates with a node device using a single virtual channel. It is an object of the present invention to provide a cell transmission control method of an ATM communication system capable of polling and receiving data from a remote terminal without using an external device such as the above.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the invention of claim 1 is:
A center node device accommodating a host terminal and a node device accommodating one or more remote terminals are connected by a communication line, and data is transmitted from each remote terminal accommodated in the node device in response to a transmission request from the host terminal. In the ATM communication system for collecting, the node device converts the data from the remote terminal into an ATM cell and outputs the ATM cell. The ATM device transmits the ATM cell from the ATM conversion processing unit to the transmission request. ATM cell transmission control means for controlling according to an activation signal from the remote terminal based on the above, wherein the node device uses a single virtual channel to transmit data from the remote terminal in response to a transmission request from the host terminal. The transmission is controlled.
[0009]
The invention of claim 2 is the invention according to claim 1,
The cell transmission control means controls to transmit the converted ATM cell only during a period when the activation signal from the remote terminal indicates the activation state.
[0010]
The invention according to claim 3 is the invention according to claim 1,
The ATM cell conversion processing means converts data from the remote terminal into an ATM adaptation layer (AAL) type 1 type cell.
[0011]
The invention according to claim 4 is the invention according to claim 3,
The ATM cell conversion processing means inserts dummy data into a portion less than one cell when converting data received from the remote terminal into an AAL1 format cell.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.
[0013]
FIG. 1 is a diagram showing an overall configuration of a communication system according to one embodiment of the present invention.
[0014]
As shown in FIG. 1, this communication system has a configuration in which a center switch node device 2 that accommodates a host terminal 1 and a plurality of switch node devices 4 that accommodate local terminals 3 are linearly connected by a transmission line 5. Each switch node device 4 is provided with a switch component 41 for exchanging ATM cells and a local terminal interface 42 serving as an interface with the local terminal 3 connected to the own node.
[0015]
Here, the center switch node device 2 manages each switch node device 4 as a whole. In the switch node device 4, the switch component 41 causes a signal transmitted from the upstream via the transmission line 5 to flow to the downstream, and exchanges information with the local terminal interface 42.
[0016]
In the figure, a transmission request signal is transmitted from the host terminal 1 to each of the local terminals 3 using the virtual channel VC = n in the transmission path 5, and the transmission request signal is transmitted from the local terminal 3 which has received the transmission request signal. A polling operation in which the switch node device 4 transmits a response cell to the host terminal using the virtual channel VC = n + I according to the cell transmission control procedure of the present invention is shown in FIG.
[0017]
FIG. 2 is a diagram showing the overall configuration of the local terminal interface 42 shown in FIG. As shown in FIG. 2, the local terminal interface 42 includes an audio converter 421, an AAL1 frame processor 422, an activation signal processor 423, and a CPU 424.
[0018]
Here, the audio converter 421 performs a PCM (Pulse Code Modulation) encoding of the analog signal from the local terminal 3 and converts it into a digital signal of, for example, 64 kbps, or is output from an AAL1 frame processor 422 described later. A process of converting a 64 kbps digital signal into an analog signal is performed.
[0019]
The AAL1 frame processing unit 422 converts the digital signal output from the audio conversion unit 421 into an ATM adaptation layer type 1 (AAL1) format cell, puts it on the AAL1 frame, and outputs it to the switch component 41, or a switch configuration. The processing of removing the header and the like from the AAL1 frame input from the part 41 and extracting the AAL1 format cell and converting it into a 64 kbps digital signal is performed.
[0020]
The activation signal processing unit 423 detects an activation signal (S1) from the local terminal 3 and sends the detected activation signal (S1) to a CPU 424 described later. This activation signal is issued from the local terminal 3 upon receiving a polling request from the host terminal 1.
[0021]
The CPU 424 controls the transmission timing of the AAL1 frame from the AAL1 frame processing unit 422 based on the activation signal received from the activation signal processing unit 423.
[0022]
Note that the local terminal 3 shown in FIG. 2 has an interface capable of outputting a start signal before transmitting data, and an example of a terminal having such an interface is a weather telemeter.
[0023]
Next, a series of operations in the local terminal interface 42 having such a configuration will be described.
First, as shown in FIG. 1, the host terminal 1 transmits a polling request to the local terminal 3.
[0024]
At this time, in the local terminal interface 42 of the switch node device 4, the data (the polling request) received from the switch component 41 is transmitted to the AAL1 frame processing unit 422 regardless of the activation signal input to the activation signal processing unit 423. The header and the like are removed from the AAL1 frame, transmitted to the audio converter 421, converted into an analog signal, and then output to the local terminal 3.
[0025]
Then, the local terminal 3 transmits the data (D) to the host terminal 1 only when the address data added to the received data is the address for the own station. Note that the data (D) is converted into an analog signal by a modem or the like in the local terminal 3 and transmitted to the voice conversion unit 421.
[0026]
The audio converter 421 performs PCM encoding on the analog signal from the local terminal 3 to convert it into digital data of 64 kbps, and then outputs the digital data to the AAL1 frame processor 422.
[0027]
When transmitting the data (D), the local terminal 3 activates the activation signal (S1). The activation signal processing unit 423 detects the activation signal (S1), and the CPU 424 controls the transmission timing of the AAL1 cell based on the activation signal (S1).
[0028]
That is, the AAL1 frame processing unit 422 converts the data input from the voice conversion unit 421 into AAL1 cells and adds necessary header information only during a period when the activation signal detected by the activation signal processing unit 423 indicates the activation state. Then, the cell transmission control for generating and outputting the AAL1 frame is performed.
[0029]
In the above embodiment, the start signal (S1) from the local terminal 3 varies depending on various interfaces. For example, in the case of an analog voice interface, an SS signal (selection signal) or a contact signal, and in the case of a V24 / 35 interface, a modem It is assumed that the RS signal among the control signals is used.
[0030]
The timing at which the activation signal is activated depends on the local terminal 3 accommodated in each switch node device 4. Generally, a unique address designating the local terminal 3 included in the data from the host terminal 1 is used. When the matching local terminal 3 responds to the communication from the host terminal 1 (data transmission), the local terminal 3 transmits the data with the activation signal in the activated state immediately before transmitting the data.
[0031]
In addition, since a plurality of local terminals 3 transmit data by the address indicating the local terminal 3 from the host terminal 1, the plural terminals do not transmit data at the same time.
[0032]
According to such a configuration, when polling is performed, the same VC can be allocated in advance for each local terminal existing on the network.
[0033]
FIG. 3 shows another example of the communication system according to the present invention, in which a local terminal interface 42 serving as an interface with the local terminal 3 and a switch component 41 are connected via an input / output port 425. Each switch component 41 and the center switch node device 2 that accommodates the host terminal 1 are connected in a loop by the transmission line 5.
[0034]
Here, the switch component 41 flows a signal transmitted from the upstream through the transmission line 5 to the downstream, and exchanges information with the local terminal interface 42 via the input / output port 425.
[0035]
Further, the local terminal interface 42 has a configuration similar to that of FIG. As a result, as described above, in response to the polling request from the host terminal 1, control is performed to convert the data from the local terminal 3 into cells based on the activation signal from the local terminal 3 and to transmit the data.
[0036]
Next, a meteorological telemeter system will be described as a specific example of the ATM communication system in FIG.
[0037]
FIG. 4 is a diagram showing the overall configuration of the weather telemeter system according to the present invention.
[0038]
In FIG. 4, in this weather telemeter system, an ATM node device 7 containing a TM (telemeter) master unit 6, an ATM node device 7 containing a TM (telemeter) slave unit (1) 8, and a TM (telemeter) slave unit An ATM node device 7 accommodating the machine (2) 9 is connected by a transmission line 10 in a ring shape.
[0039]
Here, the ATM node device 7 includes an ATM switch 7a for exchanging ATM cells, an AAL1 frame processing unit 7b for processing an AAL1 frame, a TM master unit 6 or TM slave unit (1) 8, and a TM slave unit to be accommodated. (2) 4W (4-wire interface) 7c serving as an interface with 9;
[0040]
The 4W (4-wire interface) has a configuration corresponding to the portion surrounded by the dotted line shown in FIG.
[0041]
FIG. 5 is a diagram showing the data transmission / reception timing of the present meteorological telemeter system. FIG. 5 (a) shows the transmission timing of the polling request of the observation data of the TM base unit 6, and FIG. The transmission timing of the observation response data transmitted from the TM slave unit (1) 8 in response to the polling request data is shown. FIG. 3C shows that the TM slave unit (2) responds to the polling request data. It shows the transmission timing of the observation response data to be transmitted. The start signal (S1) and the observation data (D) shown in FIG. 5 correspond to (S1) and (D) shown in FIG.
[0042]
FIG. 6 is a diagram showing the start signals of the TM slave units (1) 8 and (2) 9 and the transmission timing of the telemeter data (cell) from the ATM node device 7 in this weather telemeter system. (A) shows an activation signal (S1) of the TM slave unit (1) 8, and (b) shows a cell transmission enable signal (S2) for controlling transmission of telemeter data. The start signal (S1) and the cell transmission enable signal (S2) shown in FIG. 6 correspond to (S1) and (S2) shown in FIG. In FIG. 6, the shift between the ranges indicated by the activation signal (S1) and the cell transmission enable signal (S2) occurs due to the processing time.
[0043]
Next, the operation of the weather telemeter system will be described.
[0044]
In FIG. 4, an observation data transmission request is transmitted from the TM parent device 6 to each of the TM child devices (1) 8 and (2) 9 (FIG. 5 (a)). This request is transmitted to a plurality of TM slave units at the same time.
[0045]
Each of the TM slave units (1) 8 and (2) 9 receiving this data transmission request waits for a data transmission delay time set in advance by the slave unit number, and thereafter transmits the observation data to the TM master unit 6. (FIGS. 5B and 5C). In FIG. 5, a synchronization signal is included in the head space of the transmission request signal from the master unit, and each of the slave units 1 and 2 responds in synchronization based on the synchronization signal. . Since the same TM slave unit number does not exist on the network, the data transmission delay time set for each slave unit differs, and the data transmission timing from the slave unit becomes the same, and data is simultaneously transmitted. It does not send.
[0046]
When the TM slave unit (1) 8 and the slave unit (2) 9 transmit data, the start signal is turned on in advance as shown in FIG. As shown in b), the telemeter data (cell) is generated and transmitted from the above data only during the ON state of the start signal (S1).
[0047]
Next, the cell generation control in the AAL frame processing unit 7b at this time will be described with reference to FIG.
[0048]
FIG. 7 is a diagram showing the configuration of the AAL1 cell and the configuration of the AAL1 cell frame created by the AAL1 frame processing unit 7b shown in FIG. 4 (the same applies to the AAL1 frame processing unit 422 in FIG. 2). FIG. 7A shows a basic configuration of an AAL1 cell, and FIG. 7B shows a configuration of an AAL1 cell frame.
[0049]
In FIG. 7A, both odd-numbered cells and even-numbered cells are composed of a 5-byte header and a 48-byte payload of an ATM cell structure defined by an international standard. In the odd-numbered cells, header information necessary for AAL1 processing is used. The payload section includes a 1-byte cell sequence number and a 1-byte structure pointer, and the even-numbered cell includes a 1-byte cell sequence number as header information required for AAL1 processing.
[0050]
The cell sequence number is information indicating a serial number of a cell, and the structure pointer is information indicating a position on the payload where the data is placed.
[0051]
In FIG. 7B, the AAL1 cell frame is formed by alternately arranging odd-numbered cells and even-numbered cells shown in FIG. 7A.
[0052]
This embodiment shows a case where the data to be transmitted is composed of four 64 kbps bit rate data, of which the first 64 kbps bit rate data is the odd-numbered cell payload 46 bytes shown in FIG. , A dummy data is loaded on the other remaining portion, the next 64 kbps bit rate data is loaded on the 47 byte payload of the even-numbered cell, and the dummy data is loaded on the other remaining portion, Hereafter, the same processing is performed and transmitted as an AAL1 frame.
[0053]
As described above, according to the present invention, by inserting the dummy data, it is possible to create and transmit one cell in a short time when the AAL1 frame is created, whereby the activation signal according to the present invention is activated. Can be efficiently transmitted during the period shown in FIG.
[0054]
【The invention's effect】
As described above, according to the present invention, the node device converts the data from the remote terminal into an ATM cell and outputs the ATM cell. The ATM device transmits the ATM cell from the ATM conversion processing unit. ATM cell transmission control means for controlling according to an activation signal from the remote terminal based on a transmission request, wherein the node device transmits data from the remote terminal in response to a transmission request from the host terminal to a single virtual channel. Since transmission control is performed using the same, the host terminal can communicate with the node device with the same transmission capacity as when communicating with a single virtual channel, and, as in the related art, It is possible to poll and receive data from a remote terminal without using an external device such as an AC branching device.
[Brief description of the drawings]
FIG. 1 is a diagram showing an overall configuration of a communication system according to an embodiment of the present invention.
FIG. 2 is a diagram showing an overall configuration of a local terminal interface 42 shown in FIG.
FIG. 3 is a diagram showing another example of the communication system according to the present invention.
FIG. 4 is a diagram showing an overall configuration of a weather telemeter system according to the present invention.
FIG. 5 is a diagram showing data transmission / reception timings of the meteorological telemeter system.
FIG. 6 is a diagram showing the timing of a start signal of a telemeter slave unit of the weather telemeter system.
FIG. 7 is a diagram showing a configuration of an AAL1 cell and a configuration of an AAL1 cell frame according to the present invention.
FIG. 8 is a diagram showing an overall configuration of a conventional communication system.
[Explanation of symbols]
Reference Signs List 1 host terminal 2 center switch node device 3 local terminal 4 switch node device 41 switch component 42 local terminal interface 421 voice converter 422 AAL1 frame processor 423 activation signal processor 424 CPU
425 I / O port 5 Transmission line 6 TM (telemeter) master unit 7 ATM node device 7a ATM switch 7b AAL1 frame processing unit 7c 4W (4-wire interface)
8 TM (telemeter) slave unit (1)
9 TM (telemeter) slave unit (2)
10 Transmission line

Claims (4)

A center node device accommodating a host terminal and a node device accommodating one or more remote terminals are connected by a communication line, and data is transmitted from each remote terminal accommodated in the node device in response to a transmission request from the host terminal. In an ATM communication system to collect,
The node device includes:
ATM conversion processing means for converting data from the remote terminal into an ATM cell and outputting the ATM cell;
ATM cell transmission control means for controlling transmission of the ATM cell from the ATM conversion processing means in accordance with an activation signal from the remote terminal based on the transmission request, wherein the node device transmits the ATM cell from the host terminal. A cell transmission control method for an ATM communication system, wherein transmission of data from the remote terminal in response to a request is controlled using a single virtual channel. The cell transmission control means,
2. The cell transmission control method for an ATM communication system according to claim 1, wherein control is performed such that the converted ATM cell is transmitted only during a period when the activation signal from the remote terminal indicates the activation state. The ATM cell conversion processing means comprises:
2. The cell transmission control method according to claim 1, wherein the data from the remote terminal is converted into cells of an ATM adaptation layer (AAL) type 1 format. The ATM cell conversion processing means comprises:
4. The cell transmission control method for an ATM communication system according to claim 3, wherein when converting the data received from the remote terminal into cells of AAL1 format, dummy data is inserted into a portion less than one cell.

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