JP3427927B2 - Transmission request transmission system - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a transmission request (req).
The present invention relates to a west to send transmission system, and in particular, in a serial data communication device equipped with an asynchronous transfer mode (ATM) interface, an RS on the transmission side.
The present invention relates to a transmission request transmission system that reflects the state of a (request to send) signal on a CD (carrier detect) signal on the opposite station side.

[0002]

2. Description of the Related Art A transmission request (RS) signal is used to establish a communication start state when performing serial communication.
When using an analog network, R using carrier signal
Generally, a method of transmitting the S signal to the opposite station and controlling ON / OFF of the CD signal is adopted. like this,
In order to realize the RS signal transmission method by an ATM line which is a digital network, for example, as disclosed in Japanese Patent Laid-Open No. 05-110581 (“RS-CS delay compensation method in ATM transmission”), the RS signal state Prepare an ATM cell for transmission.

As shown in FIG. 7, according to this publication, a transmission request RS (request) is issued in a line terminating device for a game.
By starting a delay timer from the time of receiving st to send) and waiting for the transmission of data reception RD (receive data), the time from the transmission request RS on the local station side to the transmission permission CS (clear to send), Carrier detection CD (carrier d)
data reception RD (receive t)
o Data) is matched.

[0004]

However, the above-mentioned conventional technique requires a separation circuit for distinguishing it from a normal communication cell. Also, from the ATM cell data, RS
Since a circuit for extracting data for signal transmission is required, the circuit configuration becomes large and the processing becomes complicated. There is also a drawback that a timing adjustment circuit that takes into account cell fluctuations is required.

Therefore, the present invention has an object of transmitting the status of the transmission request (RS) of the own station to the opposite station without transmitting the RS signal on the ATM cell.

[0006]

The present invention for solving the above problems uses an ATM cell as a pseudo carrier.
Request transmission system for transmitting a transmission request (RS)
However, when the RS signal is turned ON,
Predetermined virtual path identification for ATM cells used as carriers
Send to the game with child and virtual channel identifiers,
After the elapse of a fixed time, the transmission permission (CS) signal is turned on
N, the data is transmitted to the game, and the game is played by the predetermined
With virtual path identifier and virtual channel identifier
When ATM cells are accumulated to a certain level, carry
A) The detection (CD) signal is turned on to receive the data .

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a receiving side DCE (distributed computing environment) of a transmission request (RS) transmission system of the present invention. The receiving DCE determines the ON state of the RS signal on the transmitting side from the number of valid cells received, and turns on the CD (carrier detect) signal.
Let

Reference numeral 11 is an ATM interface section for performing signal conversion of signals received from an ATM (asynchronous transfer mode) network, frame termination, clock extraction, and the like. 12 is
It is a cell accumulating / disassembling unit having a function of temporarily accumulating cells received from the ATM network and disassembling the cells to extract a payload. Reference numeral 13 denotes a parallel / serial conversion unit that converts a parallel signal sent from the cell storage / decomposition unit into a serial signal. Reference numeral 14 is an effective cell reception counting unit that counts the number of cells accumulated in the cell accumulating / disassembling unit. Reference numeral 16 is a DTE (data terminal equipment) interface unit that performs signal conversion and the like. 17 is a CD
ON / OFF of (carrier detect) signal
It is a CD signal control unit having a function to perform. Also, 15 is
A control unit that controls each unit.

The cell storage / decomposition unit 12 writes a target cell in a memory, disassembles the cell, and extracts effective data. The extracted data remains stored in the memory until the control unit 15 permits it. Cell storage / decomposition unit 12
Has a function of counting the number of accumulated cells, and the reception cell counting unit 14 periodically checks the number. The cells written in the memory are VPs that have been set in advance.
It is a cell having a value of I / VCI.

The control unit 15 includes a valid cell reception counting unit 1
Check the number of received cells counted by 4 and if the number reaches the specified number, turn on the CD signal to the CD signal controller.
Give a signal to Further, the control unit 15 outputs a signal for permitting the reading of data to the cell receiving / disassembling unit.

When reading is permitted, the cell accumulating / disassembling unit 12 converts the effective data into the parallel / serial converting unit 13.
Send to. The parallel / serial conversion unit 13 converts the parallel signal sent from the cell storage / decomposition unit 12 into a serial signal, and then the DTE interface unit 16
Send data to.

FIG. 2 is a block diagram of a transmitting side DCE (distributed computing environment) of the transmission request transmission system of the present invention. This transmission system transmits a pseudo carrier signal according to the RS signal. In the non-communication state, the data of "1" is normally input to the cell assembling unit 22.
The cells generated by the cell assembly section have a payload of all "1"
Cell. All the "1" cells are pseudo carriers.

Reference numeral 21 is an ATM (asynchronous transfer mode) interface section for performing signal conversion and frame generation. Reference numeral 23 is a serial / parallel converter that converts a serial signal into a parallel signal. Reference numeral 22 is a cell assembling unit that maps the data sent from the serial / parallel conversion unit 23 to the payload of the cell to generate the cell. Reference numeral 24 is a DTE interface unit that performs electrical and mechanical matching with a DTE (data terminal device). 25
Is a CS signal control unit that controls the ON / OFF state of a CS (clear to send) signal. Reference numeral 26 is a timer unit that manages the time from when the transmission request (RS) signal is turned on to when the transmission permission (CS) signal is turned on. Reference numeral 27 is a control unit that performs overall control.

The control unit 27 constantly monitors the RS signal, and when it detects that the RS signal is turned on, it outputs a signal for starting the timer unit 26. When the counting is completed, the timer unit 26 sends a CS signal to the CS signal control unit 25.
A signal for turning on the signal is output, and the CS signal is turned on. At the same time, the control unit 26 outputs a signal to the cell assembling unit 22 to permit cell assembling. The cell assembly unit 22 is
Assembling of cells (cell conversion of input signal) is started. At this point, the valid data SD has not been input to the cell assembly unit 22.

After the CS signal is turned on, valid data SD is transmitted from the DTE. The valid data SD is
Through the serial / parallel conversion unit 23, the cell assembly unit 2
Sent to 2. When the valid data is input to the cell assembling unit 22, a cell having the valid data stored in the payload is generated. The same VPI / VCI is given to a cell whose payload is all "1" and a cell which contains valid data SD.

FIG. 3 is a sequence diagram for explaining the operation of the transmission request transmission system of the present invention. Data terminal device DTE # 1 and distributed computing environment DCE #
1 is a device that transmits data, and one of DTE # 2
And DCE # 2 are devices that receive data.

When DTE # 1 starts communication,
The DCE # 1 is instructed to turn on the transmission request signal (RS signal). When the RS signal is turned on, the DCE # 1 sends cells to the DCE # 2 whose payloads are all "1", that is, pseudo carrier cells. This pseudo carrier cell notifies DCE # 2 that the RS signal of DCE # 1 has been turned ON.

The DCE # 2 is equipped with a memory for accumulating the received cells, and the received pseudo carrier cells are written and stored in the memory. This memory is also used to store cells for normal data communication. DCE # 2
Counts the number of accumulated cells, and when it detects that a predetermined number of cells have been accumulated, it judges that the RS signal of DCE # 1 is turned ON, and outputs the CD signal of DCE # 2 as O.
Set to N.

DCE # 2 turns on the CD signal and then
The counter is activated, and when a predetermined time is reached, the cell stored in the memory is disassembled, the parallel signal is converted into a serial signal, and the serial signal is transmitted to DTE # 2. D
The signal transmitted to TE # 2 becomes the value of the payload written in the pseudo carrier, that is, a signal of all "1", and 1 data is transmitted for the accumulated pseudo carrier cells.

DCE # 1 starts a counter when the RS signal is turned on, and C when the predetermined time is reached.
Turn on the S signal. When the CS signal is turned on, the DTE # 1 transmits the transmission data SD to the DCE # 1. The DCE # 1 converts the transmission data received from the DTE # 1 into cells and transmits the cells to the DCE # 2.

Here, a data transmission cell to be transmitted,
The above-mentioned pseudo carrier cell is provided with the same VPI / VCI value. By doing so, only one communication connection needs to be prepared in the ATM network, it is not necessary to secure a band for the pseudo carrier cell, and the RS in the ATM cell is not required.
Since the data for transmitting the signal state is not mapped, the receiving side does not need a circuit for extracting the RS signal transmission data.

When DCE # 2 receives a valid data cell after the pseudo carrier cell, the DCE # 2 writes the data cell in the memory once, disassembles the cell, and performs parallel / serial conversion, as in the case of the pseudo carrier cell. Send to DTE # 2. Thus, between DTE # 1 and DTE # 2,
Serial communication starts.

The above is the procedure for starting transmission.
Next, a procedure for stopping transmission will be described.

When DTE # 1 finishes transmitting data,
The RS signal is turned off. In DCE # 1, the RS signal is O
When it becomes FF, the CS signal is turned off, and DCE # 2
To stop sending cells to.

When DCE # 2 detects that the number of cells transmitted from DCE # 1 is exhausted and the number of cells stored in the memory in DCE # 2 is 0, it starts a timer and sets a predetermined time. When it reaches, the CD signal is turned off. DTE # 2 is D when the CD signal is turned off.
The communication with TE # 1 is terminated. When a valid cell is received within the timer start, the timer is stopped.

FIG. 4 is a flow chart for explaining the operation of the transmission request transmission system of the present invention. The control unit constantly monitors the state of the RS signal. As shown in FIG. 4, when the RS signal is OFF, the CS signal is turned OFF, the cell assembly signal is disabled, and the cell transmission is stopped.

If it is detected that the RS signal is turned on, the timer is started, and at the same time, the cell assembly permission signal is set to the permission state (enable) to start the cell generation. Until the timer expires, that is, in the non-communication state, since the data of "1" is input to the cell assembling unit, the generated cells are all cells of which the payload is "1". When the timer expires, the control unit turns on the CS signal. When the CS signal turns on, DTE # 1
Starts transmission of data SD, and SD
Data is input and output as a cell to the ATM network.

FIG. 5 is a timing chart for controlling the CD signal according to the RS signal. As shown in FIG.
When the RS signal turns on, the timer starts. At the same time, the cell assembling enable signal is turned on and cell assembling is started. Immediately after the cellization enable signal is turned on,
CS is in the OFF state, and no transmission data flows in SD. When not communicating, "1" is flowing in SD, so the generated cell has the entire payload.
When the timer is completed, the CS signal is turned on. When the CS signal is turned on, transmission data starts flowing to SD. Then, the transmission data is converted into cells.

When the RS signal is turned off, both the CS signal and the cell formation enable signal are turned off and the cell transmission is stopped. At this time, cells in the process of being generated are transmitted. Valid data and "1" data are mixedly mapped to cells around which the cellization enable signal is ON and OFF.

On the other hand, when the receiving side detects that the number of received cells has reached a predetermined number, it turns on the CD signal and starts communication. Immediately after the communication is started, the data of the pseudo carrier cell flows, that is, the data of "1" flows. Normally, when not communicating, it is in the state of "1". Do not be aware that data is flowing. When the send data arrives,
Valid data flows through the RD, and serial communication is started.

FIG. 6 is a flowchart for controlling the CD signal.

The receiving side constantly confirms the number of valid cells stored. Here, the valid cell refers to a cell having a predefined VPI / VCI. If no valid cell is received, the cell waits repeatedly for cell reception. When the cell is received, the number of received cells is checked. If the number of accumulated cells is less than N, the process waits repeatedly for reception of cells.
When the number of accumulated cells reaches the predetermined number N of cells, C
The D signal is turned on, and at the same time, a signal permitting cell disassembly is issued. Since the first received data is the data of which the payload is "1", the data of "1" is output to the DTE. Although not specified here, if the state where the number of accumulated cells is less than N continues for a long time, it is recognized as a failure. On the other hand, when no cell is received and the number N of accumulated cells becomes 0, the timer is started. If no cell is received during the timer activation period, the cell disassembly enable signal is set to a disabled state (disabled), and cell disassembly is stopped. At the same time, the CD signal is turned off.

[0033]

According to the present invention described above, an ATM cell having VPI / VCI defined for effective data communication is used as means for reflecting the state of the RS signal on the CD signal. Eliminates the need for individually defined cells for RS signaling. As a result, the number of connections can be reduced and the number of cells (bandwidth) used in the ATM network can be reduced.

Further, according to the present invention, the circuit for separating the cell for RS signal transmission and the cell for communication is unnecessary, and the circuit for adjusting the ON / OFF timing of the CD signal due to the fluctuation of the cell is unnecessary. Therefore, the hardware scale is reduced.

Further, according to the present invention, R is stored in the ATM cell.
Even in the case of the method of mapping the data indicating the S signal state, the circuit on the receiving side does not need a circuit for extracting the data, so that the circuit scale is reduced.

[Brief description of drawings]

FIG. 1 is a block diagram of a receiving DCE of a request to send (RS) delivery system of the present invention.

FIG. 2 is a block diagram of a transmission side DCE of the transmission request (RS) transmission system of the present invention.

FIG. 3 is a sequence diagram for explaining a procedure of transmitting an RS state to an opposite station.

FIG. 4 is a flowchart for RS status transmission.

FIG. 5: Time chart of RS status transmission

FIG. 6 is a flowchart of CD signal control using a pseudo carrier.

FIG. 7 is a block diagram of a conventional RS-CS delay compensation method in ATM.

[Explanation of symbols]

11, 21 ATM interface section 12 Cell storage / disassembly unit 13,23 Parallel / serial converter 14 Effective cell reception number counting unit 15 Control unit 16, 24 DTE interface section 17 CD signal controller 22 Cell assembly department 25 CS signal controller 26 timer section 27 Control unit

Front page continuation (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 29/08 H04L 12/56 H04L 29/10

Claims (4)

(57) [Claims] 1. An ATM cell is used as a pseudo carrier.
And a transmission request transmission system for transmitting a transmission request (RS), in which the own station communicates with the pseudo carrier when the RS signal is turned on.
A virtual path identifier and virtual
And sends it to an opposite station are denoted by the channel identifier, and ON the transmission permission (CS) signal at the mobile station after a predetermined time has elapsed, it sends the data to the remote station, the remote station, the predetermined virtual path identifier and virtual Chang
ATM cells with channel identifiers accumulated up to a certain level
A transmission request transmission system, wherein a carrier detection (CD) signal is turned on and the data is received when the data is transmitted. 2. The transmission request transmission system according to claim 1, wherein the pseudo carrier is an ATM cell whose payload part is all "1". 3. The transmission request transmission system according to claim 1, wherein the pseudo carrier and the data are transmitted in an ATM cell having the same virtual path identifier and virtual channel identifier. 4. When the transmission of the data ends, the own station turns off the RS signal, and then the CS
2. The transmission request transmission system according to claim 1, wherein a signal is turned off, and the game is turned off after a lapse of a set time after confirming that the reception of the data is completed.