JP3424604B2 - Data transmission system and data 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 data transmission system, and more particularly to a data transmission system and a data transmission method for transmitting an information frame by a high level data link control procedure.

[0002]

2. Description of the Related Art In high level data link control procedures,
The data transmission device can transmit an I frame up to the maximum outstanding number of information frames (hereinafter, referred to as an I frame) even if the response is not confirmed, but determines that the next I frame cannot be transmitted until the response is confirmed. Has been. Further, in the high-level data link control procedure, the data receiving device receives a response frame in which the final bit (hereinafter, referred to as F bit) is “0” when the command frame having the poll bit (hereinafter, referred to as P bit) “0” is received. It may be returned after an arbitrary time, but when the P-bit "1" command frame is received, the F-bit "1" is received.
It is decided that the response frame of will be returned immediately.

Conventionally, there has been proposed a technique for improving the data transmission efficiency in such a high level data link control procedure, but as an example thereof, Japanese Patent Laid-Open No. 5-3361.
As described in Japanese Patent Publication No. 94, the number of I frames transmitted by the transmitting means is measured, and when the count result matches the maximum outstanding number, the P bit of the I frame is set to "1" and the data is received. Confirm the response from the device, and if the counting result is less than the predetermined maximum outstanding number, set the P bit to "0" to send continuously without confirming the response from the data receiving device. There is something to do.

However, in the conventional technique, the I frame accumulated in the transmission buffer of the data transmission device cannot be released from the transmission buffer until the response confirmation from the data reception device is obtained, so that the I length of the data is long. In the case of a frame, the transmission buffer occupies a long time, and subsequent I frames cannot be stored in the transmission buffer, and the generation of I frames may be stopped or the I frames that cannot be stored may be discarded. And the reliability of data transfer is reduced.

In order to avoid the above problems,
There is a problem that it is necessary to secure a large send buffer area and the send buffer cannot be used economically.

The present invention has been made in view of the above problems, and an object of the present invention is to provide an I having a long data length.
A data transmission system capable of quickly releasing a buffer area occupied by a frame, economically using a limited transmission buffer area, and achieving improvement in transmission efficiency and reliability of data transfer, and The point is to provide a data transmission method.

[0007]

The present invention has the following constitution in order to solve the above problems. The gist of the invention according to claim 1 is a data transmission system for transmitting an information frame stored in a transmission buffer of a data transmission device to a data reception device using a high-level data link control procedure, wherein the data transmission device is , Data length recognition means for recognizing the data length of the information frame to be transmitted, data length reference value setting means for setting a reference value of the data length of the information frame as a data length reference value, and recognition by the data length recognition means The data length of the information frame is compared with the data length reference value set by the data length reference value setting means to determine whether the data length of the information frame is longer than the data length reference value. A data length determining means for determining, and the data length determining means determines that the data length of the information frame is longer than the data length reference value. When, resides in a data transmission system characterized by comprising a poll bit rewriting processing means rewritten from "0" to "1" the poll bit in the control field of the information frame. A second aspect of the present invention resides in the data transmission system according to the first aspect, wherein the data length reference value setting means sets the data length reference value to a predetermined value. . A third aspect of the present invention is provided with an empty capacity detecting means for detecting an empty capacity of the transmission buffer, wherein the data length reference value setting means is empty of the transmission buffer detected by the empty capacity detecting means. The data transmission system according to claim 1, wherein the data length reference value is set according to a capacity. A fourth aspect of the present invention is provided with an information frame counting means for counting the number of information frames transmitted in a unit time, and the data length reference value setting means is a unit counted by the information frame counting means. claims, characterized in that to set the data length reference value in accordance with the number of the information frame to be transmitted to the time
1 exists in the data transmission system. A fifth aspect of the present invention resides in a transmission sequence number storage means for storing a transmission sequence number of the information frame in which the poll bit is rewritten by the poll bit rewriting processing means, and the transmission sequence number storage means. Whether the transmission sequence number of the stored information frame is compared with the reception sequence number of the response frame from the data receiving device, and whether or not the response confirmation of the information frame transmitted by rewriting the poll bit was obtained. And a response confirmation determination means for determining that the response confirmation is obtained by the determination by the response confirmation determination means of the transmission buffer in which the information frame transmitted by rewriting the poll bit is stored. Buffer release processing means for releasing an area is provided.
The data transmission system according to any one of 1 to 4 exists. A sixth aspect of the present invention is a data transmission method for transmitting an information frame stored in a transmission buffer of a data transmission device to a data reception device using a high level data link control procedure, wherein the information to be transmitted is Recognizing the data length of the frame, setting the reference value of the data length of the information frame as a data length reference value, comparing the recognized data length of the information frame with the set data length reference value, When it is determined whether the data length of the information frame is longer than the data length reference value, and when it is determined that the data length of the information frame is longer than the data length reference value, the control of the information frame The data transmission method is characterized in that the poll bit in the field is rewritten from "0" to "1". The gist of the invention according to claim 7 resides in the data transmitting method according to claim 6, wherein the data length reference value is a predetermined value. The gist of the invention of claim 8, wherein, the detecting the free capacity of the transmission buffer, according to claim 6, wherein the setting the data length reference value according to the air capacity of the transmission buffer the detected It resides in the data transmission method. The gist of the invention according to claim 9 is to count the number of information frames transmitted in a unit time and set the data length reference value in accordance with the number of the information frames transmitted in the counted unit time. Characterized contract
The data transmission method described in claim 6 exists. Further, claim 10
The gist of the described invention is to store a transmission sequence number of the information frame in which the poll bit is rewritten, and to store the transmission sequence number of the stored information frame and a reception sequence number of a response frame from the data receiving device. And determines whether or not the response confirmation of the information frame transmitted by rewriting the poll bit has been taken, and when it is determined that the response confirmation has been taken, the poll bit is rewritten. 10. The data transmission method according to claim 6, further comprising releasing the area of the transmission buffer in which the information frame transmitted by transmitting the information frame is stored. The gist of the invention according to claim 11 resides in a storage medium storing a program capable of executing the data transmission method according to any one of claims 6 to 10.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram showing the configuration of an embodiment of a data transmission system according to the present invention.

In this embodiment, a data transmitting apparatus 10 for transmitting data and a data receiving apparatus 20 for receiving data are provided.
And a data transmission line 30 that connects the data transmitter 10 and the data receiver 20.
The data transfer between the data receiving device 20 and the data receiving device 20 is performed based on the high level data link control procedure.

The data transmission device 10 includes an I frame generator 1 for generating an information frame (hereinafter referred to as an I frame).
1 and the I-frame data length of each I-frame generated by the I-frame generation unit 11 is calculated, and the I-frame data length is set to a preset data length (hereinafter, data length reference value).
Data length analysis processing unit 12 that analyzes whether the length is longer than
When the I frame data length is longer than the data length reference value, the poll bit rewriting for changing the poll bit (hereinafter referred to as P bit) in the control field of the I frame from "0" to "1" A link between the processing unit 13 and the transmission sequence number storage unit 14 for storing the transmission sequence number (hereinafter referred to as N (S)) of the I frame in which the P bit is rewritten by the poll bit rewriting processing unit 13; The transmission processing unit 15 transmits the I frame to the data receiving device 20 after the establishment.

The I-frame generator 11 generates an I-frame and sends it to the data-length analysis processor 12, and at the same time, the data length of the generated I-frame is analyzed by the data-length analysis processor 12.
To notify.

The data length analysis processing unit 12 analyzes whether the data length of the I frame notified from the I frame generation unit 11 is longer than the data length reference value, and the analysis result is the poll bit rewriting processing unit 13. To notify.

Upon receiving the notification from the data length analysis processing unit 12, the poll bit rewriting processing unit 13 sets the P bit in the control field of the I frame when the I frame data length is longer than the data length reference value. Rewrite "0" to "1". Further, the transmission sequence number storage unit 14 is notified of the N (S) of the rewritten I frame.

The transmission sequence number storage unit 14 stores N of the I frame notified from the poll bit rewriting processing unit 13.
Store (S).

The transmission processing unit 15 releases a transmission buffer 16 for accumulating a plurality of I frames from the poll bit rewriting processing unit 13 and a buffer release process for releasing an area in the transmission buffer 16 in which I frames are accumulated. The buffer release processing unit 17 is configured by the data receiving device 20.
From the response frame (hereinafter referred to as N (R)) included in the response frame from the transmission sequence number storage unit 14 is compared with N (S) of the I frame, and the P bit I rewritten from "0" to "1"
After confirming the frame response, the I-frame in which the P bit is rewritten from "0" to "1" and the I-frame transmitted before that are released.

The data receiving apparatus 20 is the data transmitting apparatus 1
A response processing unit 2 that receives an I frame from the transmission processing unit 15 of 0 and returns a response frame for confirming the response.
Has 1.

When the P bit is "1" when the I frame from the transmission processing unit 15 is received, the response processing unit 21 immediately sets the final bit (hereinafter, referred to as F bit) of the response frame to "1". , And the created response frame is returned to the data transmission device 10. The response frame to be returned includes N (R). The response frame for which the F bit is "0" for the I frame for which the P bit is "0" is returned at an arbitrary time.

Next, the operation of this embodiment will be described in detail with reference to FIGS. FIG. 2 is a flowchart for explaining an operation at the time of transmitting an I frame in the embodiment of the data transmission system according to the present invention, and FIG.
FIG. 4 is a flowchart for explaining an operation at the time of receiving an I frame in the embodiment of the data transmission system according to the present invention, and FIG. 4 is a flowchart for receiving a response frame in the embodiment of the data transmission system according to the present invention. It is a flow chart for explaining operation at the time.

The I-frame generator 11 generates an I-frame composed of an address field, a control field, an information field, etc. (step 201).

The I frame generated by the I frame generation unit 11 is passed to the data length analysis processing unit 12, and in the data length analysis processing unit 12, the data length of the I frame notified from the I frame generation unit 11, The data length reference value is compared to analyze whether the data length of the I frame is longer than a threshold value, that is, the data length reference value (step 20).
2).

When it is determined in step 202 that the data length of the I frame is longer, the P-bit rewrite processing unit rewrites the P bit of the I frame from "0" to "1" ( Step 203).

The N (S) of the I frame whose P bit has been rewritten in step 203 is stored in the transmission sequence number storage section 14 (step 204), and the I frame is passed to the transmission processing section 15 and transmitted to the transmission buffer. 16 (step 205).

On the other hand, when it is determined in step 202 that the data length of the I frame is shorter, the I frame is passed to the transmission processing section 15 and accumulated in the transmission buffer 16 (step 205). The I frame accumulated in the transmission buffer 16 in step 205 is transmitted to the data receiving device 20 by the transmission processing unit 15 (step 2
06).

The data receiving device 20 is the data transmitting device 1
When an I frame from 0 is received (step 301),
It is checked whether the P bit value in the I frame is "0" or "1" (step 302). If the P bit value in the I frame is "0", the process returns to step 301.

When the value of the P bit in the I frame is "1", a response frame containing N (R) is immediately returned (step 303) and the process returns to step 301.

The data transmitting apparatus 10 is the data receiving apparatus 2
When a response frame from 0 is received (step 4
01), it is checked from the N (R) of the response frame whether or not the response confirmation of the I frame in which the P bit stored in the transmission sequence number storage unit 14 is rewritten to “1” can be obtained (step 402), and the response confirmation can be obtained. If not, the process returns to step 401.

When the response is confirmed, the buffer release processing unit 17 stores the I frame for which the response has been confirmed and the I frame transmitted before the I frame for which the response is confirmed in the transmission buffer 16. Area is released (step 403) and the process returns to step 401.

As described above, according to the embodiment of the present invention, the number of I-frames for which the response is unconfirmed is the maximum outstanding number for I-frames having a long data length and a high occupation rate of the transmission buffer area. Even if it does not meet
By promptly confirming the response, the buffer area occupied by the I-frame having a long data length can be released promptly, and the limited area of the transmission buffer can be economically used to improve the transmission efficiency and the data. This has the effect of improving the reliability of transfer.

Further, in the present embodiment of the present invention, the judgment of the I frame for rewriting the P bit from "0" to "1" is made by judging whether or not it is longer than the data length reference value. It is also possible to make the data length reference value, which is the reference for judgment, variable. For example, a data length reference value determined by the released area of the transmission buffer (hereinafter referred to as an empty capacity), a data length reference value determined by the number of I frames transmitted in a unit time, and the like can be considered.

When the data length reference value is determined by the empty capacity of the transmission buffer, the empty capacity detection unit for detecting the empty capacity of the transmission buffer and the data length reference value are set according to the empty capacity detected by the empty capacity detection unit. This can be realized by providing a data length reference value setting unit for setting. The data length reference value is set longer as the free space of the transmission buffer is larger, and is set shorter as the free space of the transmission buffer is smaller.

When the data length reference value is determined by the number of I frames transmitted in a unit time, the I frame count unit that counts the number of I frames transmitted in a unit time and the I frame count unit counts. This can be achieved by providing a data length reference value setting unit that sets the data length reference value according to the number of I frames transmitted in the set unit time. The data length reference value is set shorter as the number of I frames transmitted per unit time increases.
The smaller the number of I-frames transmitted per unit time, the longer the length is set.

Further, in the present embodiment of the present invention, the data length analysis processing unit 12 recognizes the data length of the I frame by the notification from the I frame generation unit 11. In, the data length of the I frame may be recognized by counting the data length between specific patterns of 1 byte provided at the beginning and the end of the I frame.

It should be noted that the present invention is not limited to the above-described embodiments, and it is obvious that each embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, etc. of the above-mentioned constituent members are not limited to those in the above-mentioned embodiment, and the number, position, shape, etc. suitable for carrying out the present invention can be adopted. In addition, in each figure, the same components are denoted by the same reference numerals.

[0035]

According to the data transmission system and the data transmission method of the present invention, the number of I-frames for which a response has not been confirmed is less than the maximum outstanding number for I-frames having a long data length and a high occupation rate of the transmission buffer area. However, by promptly confirming the response, the buffer area occupied by the I-frame having a long data length can be released promptly, and the finite transmission buffer area can be used economically, resulting in high transmission efficiency. It is possible to achieve the improvement and the reliability of data transfer.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of a data transmission system according to the present invention.

FIG. 2 is a flowchart for explaining an operation at the time of transmitting an I frame in the embodiment of the data transmission system according to the present invention.

FIG. 3 is a flowchart for explaining an operation at the time of receiving an I frame in the embodiment of the data transmission system according to the present invention.

FIG. 4 is a flowchart for explaining an operation at the time of receiving a response frame in the embodiment of the data transmission system according to the present invention.

[Explanation of symbols]

10 Data transmitter 11 I-frame generator 12 Data length analysis processing unit 13 Pole Bit Rewriting Processing Unit 14 Transmission sequence number storage 15 Transmission processing unit 16 send buffer 17 Buffer release processing unit 20 Data receiver 21 Response Processing Unit 30 transmission lines

Claims (11)

(57) [Claims] 1. A data transmission system for transmitting an information frame stored in a transmission buffer of a data transmitting device to a data receiving device by using a high level data link control procedure, wherein the data transmitting device transmits the information. Data length recognition means for recognizing the data length of the frame, data length reference value setting means for setting a reference value of the data length of the information frame as a data length reference value, and the information frame recognized by the data length recognition means Of the data length of the information frame is compared with the data length reference value set by the data length reference value setting means to determine whether or not the data length of the information frame is longer than the data length reference value. Means for determining the data length of the information frame is longer than the data length reference value, Data transmission system, characterized by comprising a poll bit in the control field of the broadcast frame from the "0" and poll bit rewriting processing means rewritten to "1". 2. The data transmission system according to claim 1, wherein the data length reference value setting means sets the data length reference value to a predetermined value. 3. An empty capacity detecting means for detecting an empty capacity of the transmission buffer, wherein the data length reference value setting means is configured to detect the empty capacity of the transmission buffer according to the empty capacity of the transmission buffer detected by the empty capacity detecting means. claim 1 Symbol, characterized in that to set the length reference value
On-board data transmission system. 4. An information frame counting means for counting the number of information frames transmitted in a unit time, wherein the data length reference value setting means is the information transmitted in the unit time counted by the information frame counting means. The data transmission system according to claim 1, wherein the data length reference value is set according to the number of frames. 5. A transmission sequence number storage means for storing a transmission sequence number of the information frame in which the poll bit is rewritten by the poll bit rewriting processing means, and the information frame stored in the transmission sequence number storage means. Of the response sequence of the response frame from the data receiving device is compared to determine whether or not the response confirmation of the information frame transmitted by rewriting the poll bit is obtained. And a buffer release for releasing the area of the transmission buffer in which the information frame transmitted by rewriting the poll bit is stored when the response confirmation is determined by the response confirmation determination means. A processing means is provided, The statement in any one of Claim 1 thru | or 4 characterized by the above-mentioned. Data transmission system. 6. A data transmission method for transmitting an information frame stored in a transmission buffer of a data transmission device to a data reception device by using a high level data link control procedure, wherein the data length of the information frame to be transmitted is recognized. Then, the reference value of the data length of the information frame is set as a data length reference value, the data length of the recognized information frame is compared with the set data length reference value, and the data length of the information frame is set. Is longer than the data length reference value, and when it is determined that the data length of the information frame is longer than the data length reference value, the poll bit in the control field of the information frame is "0" to "1"
A data transmission method characterized by rewriting to. 7. The data transmission method according to claim 6, wherein the data length reference value is a predetermined value. 8. The data according to claim 6, wherein the empty capacity of the transmission buffer is detected, and the data length reference value is set according to the detected empty capacity of the transmission buffer. Transmission method. 9. The method according to claim 6, wherein the number of information frames transmitted in a unit time is counted, and the data length reference value is set according to the number of the information frames transmitted in the counted unit time. Described data transmission method. 10. The transmission sequence number of the information frame in which the poll bit is rewritten is stored, and the transmission sequence number of the stored information frame and the reception sequence number of the response frame from the data receiving device are stored. By comparing, it is determined whether or not the response confirmation of the information frame transmitted by rewriting the poll bit is obtained, and if it is determined that the response confirmation is obtained by the determination, the poll bit is rewritten and transmitted. 10. The data transmission method according to claim 6, further comprising releasing the area of the transmission buffer in which the information frame stored is stored. 11. A storage medium in which a program capable of executing the data transmission method according to claim 6 is stored.