JPH10285147A - Data transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress an error correction coding processing time of variable length data from being increased and to transmit the data without deteriorating the transmission efficiency. SOLUTION: A data length detection section 1 at a transmitter side measures length of data to be transmitted, and an error correction coding control section 2 selects an error correction coding system depending on each data length. An error correction coding section 3 encodes the data according to the selected result and the coded data are transmitted to a network 4. On the other hand, a data length detection section 5 at a receiver side measures the length of the data received from the network 4 and an error correction decoding system corresponding to the error correction coding system is selected depending on each data length and the data are decoded.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a data transmission system, and more particularly to a data transmission system for performing error correction coding and decoding of transmission data.

[0002]

2. Description of the Related Art An example of a conventional data transmission apparatus is shown in FIG. This example is disclosed in Japanese Patent Application Laid-Open No. 4-129351. In the figure, an input video signal supplied to an input terminal is
Is input and encoded. For example, entropy coding is used for the coding of the compression coding circuit 15, and the compression coding rate is a coding method that fluctuates with time. Note that 101 is an input terminal, and 201 is an output terminal.

The variable-rate compressed encoded data output from the compression encoding circuit 15 is input to a cell conversion circuit 16. In the celling circuit 16, celling is performed in units of a pixel block including a fixed number of pixels. That is, as shown in FIG. 12, one piece of compressed coded data obtained by performing compression coding on an input video signal for a certain period T, that is, a signal obtained by compressing and coding a pixel block including a certain number of pixels. Alternatively, a plurality of cells are configured.

[0004] In the case of implementing such cell formation, a surplus portion may occur because the data amount of the encoded output of a certain pixel block does not always match an integral multiple of the cell. Therefore, so-called dummy data D such as all “0” is inserted into the remaining portion. As described above, one or a plurality of (integer) cells are generated for each pixel block, and input to the next variable-length cell blocking circuit 17.

In this variable-length cell blocking circuit 17,
A variable-length cell block is formed. FIG.
In the example shown in FIG.
The cell generated from the video signal for a certain period T is a cell block. That is, one or a plurality of cells obtained by forming cells in units of pixel blocks become a cell block.

The variable-length cell blocking output obtained by the variable-length cell blocking circuit 17 is input to an error correction coding circuit 18 and coded. However, since the input to the error correction coding circuit 18 is a variable length cell block, its output is as shown in FIG. FIG.
3, the pixel blocks P1-1 and P1-2,
Inspection cells P2-1 and P2-2 in the pixel block and P3-1 and P3-2 in the pixel block are provided, and two inspection cells K are added to each cell block.

As described above, in order to perform error correction coding on a variable-length cell block, a sufficiently long fixed-length cell block is assumed, and all "0" s are added to a portion corresponding to a difference from an actual variable-length cell block. Cell consisting of data (dummy cell)
Error correction coding is performed assuming that there is an error. Thus, data transmission is enabled by performing error correction while minimizing the transmission delay.

[0008]

In the above-mentioned prior art, error correction encoding is performed in which redundant bits for error correction having a fixed length are added irrespective of the actual length of variable length data. Therefore, even when the actual data length is short, a certain length of error correction redundant bits is added. Therefore, when the appearance frequency of input data having a short data length is high, there is a disadvantage that the error correction coding processing time increases and transmission efficiency deteriorates. In the case of a random error, if the input data length is half, the same error correction capability can be obtained with half the redundant bits.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned drawbacks of the prior art, and has as its object to suppress an increase in error correction coding processing time for variable-length data and to reduce transmission efficiency. An object of the present invention is to provide a data transmission system capable of performing data transmission.

[0010]

According to the present invention, there is provided a data transmission system, comprising: a selector for selecting one of a plurality of error correction coding systems according to a data length of data to be transmitted; Encoding means for performing error correction encoding on the data and outputting the result.

Further, the data transmission system according to the present invention comprises a selecting means for selecting one of a plurality of error correction decoding coding systems according to a data length of received data; Decoding means for performing error correction decoding and outputting the result.

The data length of the data is measured by a counter or added to the data. The selecting means selects an error-correcting code scheme that maintains a predetermined error-correcting capability and minimizes the number of redundant bits for error correction to be added, from among the plurality of error-correcting coding schemes. And

In short, in the data transmission system, error correction coding is performed on variable-length data by adding, for each data length, a redundant bit for error correction which is a minimum necessary for a predetermined error correction capability. I have. Therefore, if the necessary error correction redundant bit is T when the data length is L, and if the data length is L / 2, to obtain the same error correction capability (in the case of a random error), In other words, it is only necessary to perform error correction coding in which the redundant bits for error correction are T / 2. Therefore, it is possible to shorten the error correction encoding processing time and improve the transmission efficiency.

[0014]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of a data transmission system according to the present invention. In the figure,
The data transmission system according to the present embodiment includes a data length detection unit 1 that detects a data length of variable length data having a predetermined frame configuration, and a data length detection unit that detects a data length of the variable length data corresponding to the variable length data. An error correction coding control unit 2 and an error correction coding unit 3 for performing error correction coding that does not lower the error correction capability below a certain level and minimizes the number of added redundant bits. I have.

Further, the present system comprises a data length detecting section 5 for detecting the data length of the error-correction coded data having an arbitrary length, and an error corresponding to the detected data length based on a predetermined rule. It is configured to include an error correction decoding control unit 6 and an error correction decoding unit 7 that perform correction decoding on input data. 4 is a network.

In such a configuration, variable length data having a predetermined frame configuration is input from the input terminal 100 to the data length detector 1 and the error correction encoder 3, respectively. The data length detection unit 1 detects the data length L of the variable length data forming the frame based on the above-described rule of the frame configuration. Next, based on the data length L of the variable-length data detected by the data length detection unit 1, the error correction coding control unit 2 maintains the predetermined error correction capability and adds an additional error correction redundant bit. Is selected and the selection signal S is output to the error correction coding unit 3.

The error correction coding unit 3 performs error correction coding on the input variable length data in accordance with the error correction coding system selection signal S output from the error correction coding control unit 2. After that, the encoded data is transmitted to the network 4.

The error correction coded data received through the network 4 is input to the data length detection unit 5 and the error correction decoding unit 7.

In the data length detector 5, the data length detector 1
Similarly to the above, the data length L ′ of the received error-correction coded data is detected based on the rules of the frame configuration, and is output to the error-correction decoding control unit 6. The error correction decoding control unit 6 determines the error correction coding system selected by the error correction coding control unit 2 based on the data length L ′ detected by the data length detection unit 5. Then, the control unit 6 selects an error correction decoding method corresponding to the error correction coding method, and selects the selection signal S
'To the error correction decoding unit 7.

Finally, the error correction decoding unit 7 performs error correction decoding on the received error correction encoded data in accordance with the error correction decoding system selection signal S 'from the error correction decoding control unit 6. And outputs it to the output terminal 200.

The above operation will be described in detail with reference to FIGS. First, variable-length data having a frame structure in which a frame start code and a frame end code (both are assumed to be unique codes) are added before and after the variable-length data as shown in FIG.
It is assumed that the data is input from the input terminal to the data length detection unit 1 and the error correction coding unit 3.

The data length detection unit 1 first detects a frame start code, and then starts counting the number of variable length data based on the frame start code. When the frame end code is detected, the counting is stopped, and the data length L (see FIG. 2) of the variable length data constituting the frame is obtained.

Next, based on the data length L of the variable length data detected by the data length detection unit 1, the error correction coding control unit 2 keeps a predetermined error correction capability and adds an error to be added. An error correction encoding method that minimizes the number of redundant bits for correction is selected. Then, it outputs the selection signal S to the error correction coding unit 3.

Here, there are the following methods for selecting an error correction coding method. That is, a correspondence table between the data length Ln and the error correction coding method FECCn shown in FIG. 4A is prepared, and the error correction coding control unit 2 selects the error correction coding method with reference to the table. . In addition,
Various methods are conceivable. The relationship between the data length Ln in the correspondence table shown in FIG. 7A and the number of redundant bits Tn required for the error correction coding scheme FECCn is basically proportional. Here, when a random error is assumed, if the relationship between the data L1 and the data length Ln is L1 = Ln / 2, the relationship between the corresponding redundant bit T1 and the data length Tn is also T1 = Tn / 2.

The error correction coding unit 3 performs error correction coding on the input variable length data in accordance with the error correction coding system selection signal S output from the error correction coding control unit 2. After adding redundant bits to the variable length data as shown in FIG. 3, the encoded data is transmitted to the network 4.

The error-correction coded data (see FIG. 3) received through the network 4 is input to the data-length detector 5 and the error-correction decoder 7.

In the data length detecting section 5, the data length detecting section 1
Similarly to the above, based on the frame start code and the frame end code of the frame signal (see FIG. 3), the data length L '(see FIG. 3) of the received error correction coded data is obtained, and the error correction decoding control unit 6 is output.

The error correction decoding control unit 6 performs error correction decoding corresponding to the error correction coding system selected by the error correction coding control unit 2 based on the data length L 'detected by the data length detection unit 5. 4B is selected with reference to the correspondence table shown in FIG.
Output to Here, in the tables of FIGS. 4A and 4B, L1, L2, L3..., Ln and L1 ′, L2 ′, L3
'..., Ln' and FECC1, FECC2, FECC3
…, FECCn and FECD1, FECD2, FECD3
.., FECDn are in one-to-one correspondence.

Finally, the error correction decoding unit 7 performs error correction decoding on the received error correction encoded data in accordance with the error correction decoding system selection signal S 'from the error correction decoding control unit 6. And output to the output terminal.

[0031]

Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 5 shows the configuration of the embodiment of the present invention.

Input data having a fixed data length N is input to the variable length coding unit 8 from an input terminal. The variable length coding unit 8 performs variable length coding on the input data, and outputs the variable length coded data to the frame forming unit 9. The frame forming section 9 adds a start code and an end code to the input variable-length coded data based on a predetermined rule to form a frame. The variable-length encoded data framed by the frame composing section 9 is input to the data length detecting section 1 and the error correcting encoding section 3 respectively.

The data length detecting section 1 detects the data length L of the variable length data framed based on the above-mentioned frame configuration rules. Next, based on the data length L of the variable length data detected by the data length detection unit 1, the error correction coding control unit 2
An error correction coding scheme that maintains a preset error correction capability P (determined from the quality of the network, the quality required by the service to be applied, etc.) and adds the minimum number of redundant bits for error correction to be added. And outputs the selection signal S to the error correction encoding unit 3.

The error correction coding unit 3 performs error correction coding on the input frame-length variable data in accordance with the error correction coding system selection signal S output from the error correction coding control unit 2. After the conversion, the data is output to the frame forming unit 10. The frame structuring unit 10 performs framing on the input error-correction coded data based on the same rule as that of the frame structuring unit 9, and transmits the frame-corrected error-correction coded data to the network 4.

The error correction coded data received through the network 4 is input to the data length detection unit 5 and the error correction decoding unit 7.

In the data length detecting section 5, the data length detecting section 1
Similarly to the above, the data length L ′ of the received error correction coded data is detected based on the rule of the frame configuration, and is output to the error correction decoding control unit 6. The error correction decoding control unit 6 determines the error correction coding system selected by the error correction coding control unit 2 based on the data length L ′ detected by the data length detection unit 5. An error correction decoding method corresponding to the error correction coding method is selected, and the selection signal S ′ is output to the error correction decoding unit 7.

In the error correction decoding section 7, the error correction decoding system selection signal S 'from the error correction decoding control section 6 is output.
, The received error-correction coded data is subjected to error-correction decoding, and the resulting framed variable-length coded data is subjected to a frame separation unit 11.
Output to

The frame separating section 11 deletes the start code and end code added by the frame forming section 10 from the input framed variable length coded data, and forms the framed variable length coded data. , And separates only the variable-length coded data from the data, and outputs it to the variable-length decoding unit 12. Finally, the variable length decoding unit 12 performs variable length decoding on the input variable length encoded data, restores the input data input from the input terminal, and outputs
Output to 00.

Next, the operation of the embodiment of the present invention will be described with reference to FIG.
This will be described in detail with reference to FIGS.

As shown in FIG. 6A, input data a having a fixed data length N is input to the variable length coding unit 8 from an input terminal. The variable-length coding unit 8 performs variable-length coding on the input data a, and outputs variable-length coded data b as shown in FIG. The frame composing section 9 adds a frame start code S and a frame end code E before and after the input variable-length encoded data b.
(Both are assumed to be unique word codes) to form a frame. Then, the data is output to the data length detector 1 and the error correction encoder 3 as framed variable-length encoded data c (see FIG. 6C).

The data length detector 1 first detects the frame start code S, starts counting the number of variable-length data based on the frame start code S, and outputs the frame end code E
Is detected, the counting is stopped, and the data length L (see FIG. 6C) of the variable length data constituting the frame is obtained.

Next, based on the data length L of the variable length data detected by the data length detection unit 1, the error correction coding control unit 2 adds the data while maintaining the error correction capability P set in advance. An error correction encoding method that minimizes the number of redundant bits for error correction is selected, and the selected signal S is output to the error correction encoding unit 3.

Here, a method of selecting an error correction coding system will be described with reference to FIG. FIG. 7 shows Reed-Solomon as an error correction coding method.
The data length L is 20, 30, 40,...
An example in which seven types of values of 0 can be taken is shown. In addition, as for the error correction capability P set in the example of FIG. 7, when the minimum data length L = 2 bytes is targeted, Reed-Solomon encoding (RS (2
4, 20)), and it is possible to correct errors up to a maximum of 2 bytes.

As shown in FIG. 7A, the data length L (20, 30, 40,
, 80 bytes) and an error correction coding system using RS (24 (20), RS (36, 3)
0), RS (48, 80)... RS (96, 80)), and the error correction coding control unit 2 selects an error correction coding method with reference to the table. Also,
The relationship between the data length L in the correspondence table shown in FIG. 7A and the number of redundant bits T required for error correction encoding is proportional, and in this example, L / 5 = T.

Returning to FIG. 6, the error correction coding unit 3 applies the Reed-Solomon to the input variable length data in accordance with the error correction coding system selection signal S output from the error correction coding control unit 2. Encoding is performed, and the frame composing unit 10 converts the encoded data into error correction encoded data d (see FIG. 6D).
Output to The frame structuring unit 10 performs framing on the input error-correction coded data in the same manner as the frame structuring unit 9, and converts the frame-corrected error-correction coded data e (see FIG. 6E). Send to network 4.

The frame-corrected coded error data e received through the network 4 is
And the error correction decoding unit 7 respectively. The data length detection unit 5 detects the frame start code S and the end code E based on the rules of the frame configuration (see FIG. 6E), as in the data length detection unit 1, and converts the received frame into a received frame. The data length L 'of the error correction encoded data e (FIG. 6)
(See (e)) and outputs it to the error correction decoding control section 6.

The error correction decoding control section 6 selects the error correction coding scheme (Reed-Solomon coding) selected by the error correction coding control section 2 based on the data length L 'detected by the data length detection section 5. RS (24, 20), etc.) with reference to the correspondence table shown in FIG. 7B, and outputs the selected signal S ′ to the error correction decoding unit 7. Here, the data length L (20, 30, 40,..., 80 bytes) in FIG. 7A and the data length L ′ (24, 36,..., 96) in FIG.
(Data length L ') = (data length L) + (redundant bit T)
, Each has a one-to-one correspondence.

The error correction decoding unit 7 performs error correction decoding on the received framed error correction encoded data e in accordance with the error correction decoding method selection signal S ′ from the error correction control unit 6. Is performed, and the resulting framed variable-length encoded data f (FIG. 6)
(See (f)) to the frame separation unit 11.

The frame separating unit 11 deletes the start code and the end code added by the frame forming unit 10 from the input framed variable length coded data f, and forms the framed variable length coded data f. Only the variable-length coded data g (see FIG. 6G) is separated from the data f and output to the variable-length decoding unit 12. Finally, in the variable length decoding unit 12, the input variable length encoded data g
Is subjected to variable-length decoding, and the input data a input from the input terminal 100 is restored and output to the output terminal.

The encoding and decoding are performed in the same manner for the data h in FIG. 6 (h). That is, the data h becomes the variable-length coded data i in FIG. 7I, and becomes the data j in FIG. 7J by adding the frame start code S and the frame end code E. Thereafter, the data is coded according to the selection signal S to become data k in FIG.

The data k is framed to become the data 1 shown in FIG. Then, the data 1 is decoded and becomes the data m in FIG. The start code S and the end code E are deleted from the data m, and the data n shown in FIG.

Next, another embodiment of the present system will be described with reference to FIG. Variable length data having a predetermined frame configuration is input from the input terminal 100 to the data length detection unit 1 and the data length multiplexing unit 13, respectively.

The data length detection unit 1 detects the data length L of the variable length data forming the frame based on the above-mentioned rules for the frame configuration. Next, in the data length multiplexing unit 13,
The data length “L” detected by the data length detection unit 1 is multiplexed to variable length data having the above-mentioned frame configuration, and output to the error correction coding unit 3. FIG. 9 shows an example in which the data length “L” is multiplexed.

On the other hand, the error correction coding control unit 2 keeps a predetermined error correction capability based on the data length L and adds the minimum number of error correction redundant bits. A method is selected, and the selection signal S is output to the error correction coding unit 3. In the error correction encoding unit 3,
Error correction coding is performed on the variable-length data having a frame configuration output from the data length multiplexing unit 13 in accordance with the error correction coding system selection signal S output from the error correction coding control unit 2. After that, the encoded data is transmitted to the network 4. The transmitted encoded data is shown in FIG.

The error-correction coded data received via the network 4 is input to the data length separation unit 14 and the error correction decoding unit 7. The data length separation unit 14 separates the data length L of the variable length data multiplexed by the data length multiplexing unit 13 on the basis of the frame configuration rule, and outputs the data length L to the error correction decoding control unit 6. The error correction decoding control unit 6 determines the error correction coding method selected by the error correction coding control unit 2 based on the data length “L” output from the data length separation unit 14. Then, an error correction decoding method corresponding to the error correction coding method is selected, and the selection signal S ′ is output to the error correction decoding unit 7. Finally, in the error correction decoding unit 7, according to the error correction decoding system selection signal S 'from the error correction decoding control unit 6,
The received error-correction coded data is subjected to error-correction decoding and output to an output terminal 200.

As described above, in the present system, the transmitting side selects one of a plurality of error correction coding systems according to the data length of the data to be transmitted, and performs error checking on the data in the selected system. After performing correction coding and outputting, the receiving side selects one of a plurality of error correction decoding coding systems according to the data length of the received data,
The error correction decoding is performed on the received data according to the selected method and the data is output. As a result, when variable-length data is transmitted by performing error correction coding, data transmission can be performed without suppressing an increase in error correction coding processing time and without reducing transmission efficiency. The data length of the data to be transmitted is measured using a counter or the like, or is multiplexed and added to the data in advance.

In the above description, the well-known Reed-Solomon coding method is used as the coding / decoding method.
Obviously, other schemes may be used. For example, BCH (Bose-Chaudhuri-Hoc)
quenchem coding, Hamming
g) A coding method, a Viterbi coding method, or the like may be used. However, the Reed-Solomon coding method is the most widespread, and it is best to use this method.

The present invention can further take the following aspects in connection with the description of the claims.

(10) The data transmission system according to any one of claims 1 to 4, wherein one of the plurality of error correction coding systems is a Reed-Solomon coding system.

(11) The data transmission system according to any one of claims 5 to 8, wherein one of the plurality of error correction decoding systems is a decoding system of a Reed-Solomon coding system. .

(12) The data transmission system according to claim 9, further comprising a measuring means for measuring a data length of the data.

(13) The data transmission system according to (9), wherein the information indicating the data length of the data is added to the data.

(14) The error correcting code system which maintains a predetermined error correcting capability and minimizes the number of redundant bits for error correction to be added is selected from the plurality of error correcting code systems. 14. The data transmission system according to claim 9, wherein (1) is selected.

[0064]

As described above, the present invention detects the data length of variable-length data, maintains the error correction capability at a constant level for each data length, and adds the additional redundant bits. By selecting and executing the error correction coding method that minimizes the number, when error correction coding is performed and variable length data is transmitted, increase in error correction coding processing time is suppressed and transmission efficiency is not reduced. In addition, there is an effect that data transmission can be performed.

[Brief description of the drawings]

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

FIG. 2 is a diagram illustrating a frame configuration of variable-length data in the data transmission system of FIG. 1;

FIG. 3 is a diagram illustrating a frame configuration of error correction encoded data in the data transmission system of FIG. 1;

4A is a diagram showing a correspondence between a data length and an error correction coding system in the data transmission system of FIG. 1, and FIG.
FIG. 2 is a diagram showing a correspondence between a data length and an error correction decoding system in the data transmission system of FIG.

FIG. 5 is a block diagram showing a more specific embodiment of the data transmission system of FIG. 1;

6 (a) to 6 (n) are diagrams showing data processed by each unit of the data transmission system of FIG.

7A is a diagram showing a correspondence between a data length and an error correction coding method in the data transmission system of FIG. 5, and FIG.
FIG. 6 is a diagram showing a correspondence between a data length and an error correction decoding method in the data transmission system of FIG. FIG. 3 is a diagram illustrating a correspondence between a data length and an error correction coding method.

FIG. 8 is a block diagram showing a configuration of a data transmission system according to another embodiment of the present invention.

9 is a diagram illustrating a frame configuration of variable-length data in the data transmission system of FIG. 8;

FIG. 10 is a diagram illustrating a frame configuration of error correction encoded data in the data transmission system of FIG. 8;

FIG. 11 is a block diagram showing a configuration of a conventional data transmission system.

FIG. 12 is a time chart showing the operation of the system in FIG. 11;

FIG. 13 is a diagram illustrating an example of error correction coded data in the system of FIG. 11;

[Explanation of symbols]

 1, 5 Data length detection unit 2 Error correction coding control unit 3 Error correction coding unit 4 Network 6 Error correction decoding control unit 7 Error correction decoding unit 8 Variable length coding unit 9, 10 Frame configuration unit 11 Frame separation Unit 12 variable length decoding unit 13 data length multiplexing unit 14 data length separation unit

Claims (9)

[Claims] 1. A selecting means for selecting one of a plurality of error correction coding systems according to the data length of data to be transmitted, and performing error correction coding on the data in the selected system and outputting the data. A data transmission system comprising: 2. The data transmission system according to claim 1, further comprising measuring means for measuring a data length of said data. 3. The data transmission system according to claim 1, wherein the information indicating the data length of the data is added to the data. 4. The method according to claim 1, wherein the selecting means selects an error correction code scheme that maintains a predetermined error correction capability and minimizes the number of error correction redundant bits to be added, among the plurality of error correction code schemes. Claim 1 characterized by selecting
4. The data transmission system according to any one of 3. 5. A selecting means for selecting one of a plurality of error correction decoding coding systems according to a data length of received data, and performing error correction decoding on the data in the selected system and outputting the data. A data transmission system comprising: 6. The data transmission system according to claim 5, further comprising measuring means for measuring a data length of said data. 7. The data transmission system according to claim 5, wherein the information indicating the data length of the data is added to the data. 8. The error correction decoding method according to claim 1, wherein the error correction decoding method maintains a predetermined error correction capability and minimizes the number of error correction redundant bits to be added. Claim 5 characterized by selecting
8. The data transmission system according to any one of 7. 9. A transmitting means for selecting one of a plurality of error correction coding systems according to the data length of data to be transmitted, and error correction coding for the data in the selected system. And a coding means for performing one of a plurality of error correction decoding coding methods on the receiving side according to the data length of the received data. Decoding means for performing error correction decoding on the data and outputting the result.