JP3159243B2 - Data compression device - 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 compression apparatus for automatically controlling compression or non-compression according to the data length of transmission data.

[0002]

2. Description of the Related Art Conventionally, in this type of data compression apparatus, transmission data transmitted from a data terminal apparatus (hereinafter, referred to as DTE) is considered to be a unique algorithm or the most suitable among a plurality of compression algorithms. An analogous algorithm is selected, transmission data is always compressed, and then transmitted (transmitted) to a data line terminating device (hereinafter referred to as DCE).

Known techniques related to such data compression include, for example, a data compression control device and a data decompression control device disclosed in JP-A-4-242424 and JP-A-4-359315. 5-2071
No. 78,202, JP-A-6-202.
No. 845 discloses a transmission data compression method and apparatus.

[0004]

The data compression apparatus described above does not have a function of automatically controlling compression or non-compression according to the data length of transmission data. When transmitted, the compression effect is reduced, and the overhead in the data compression unit is lower in the case where the data is used (through the data compression unit) than in the case where the data compression unit is not used due to the overhead in the data compression unit. There's a problem.

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and its technical problem is to achieve a sufficient compression effect regardless of the data length of transmission data and to improve the throughput. It is an object of the present invention to provide a data compression apparatus for obtaining such data.

[0006]

According to the present invention, a DTE
DTE-side transmission buffer that stores transmission data transmitted from the DTE as transmission storage data, a data compression unit that compresses the transmission storage data with a specific algorithm to generate compressed data, and stores the compressed data and transmits it to the DCE as transmission data. A transmission buffer on the DCE side for transmission, a reception buffer on the DCE side for storing transmission data transmitted from the DCE as reception accumulation data, a data decompression unit for decompressing the reception accumulation data by a specific algorithm to decompress data, And a first switch unit for switching and outputting the transmission accumulated data or the compressed data, and identifying and notifying the transmission accumulated data or the compressed data. To add an identification bit to the transmitted accumulated data or the compressed data for A first insertion unit, based on the data length of the transmission accumulation data, controls the first switch unit to select the transmission accumulation data when the data length is smaller than a specific number, and controls the bit insertion unit. A data monitoring control unit for adding an identification bit to the transmission accumulation data;
As the TE side transmission buffer, a data compression device for notifying the data monitoring control unit of the data length of the transmission accumulation data can be obtained.

Further, according to the present invention, in the data compression device, the data monitoring control unit controls the first switch unit when the data length becomes a specific number or more to select the compressed data, and , A data compression apparatus is provided which controls the bit insertion unit to add an identification bit to the compressed data.

Further, according to the present invention, in any one of the above data compression devices, the second switch unit for switching and outputting the received accumulated data or the decompressed data, and monitoring the received accumulated data to determine whether the received accumulated data is the same based on the identification bit. It is determined whether the data is compressed or compressed. If the data is uncompressed, the identification bit is discarded and the second switch unit is controlled to select the received and stored data. A data compression device is provided that includes an identification bit detection control unit that selects the decompressed data by controlling the second switch unit after discarding the bits.

[0009]

According to the data compression apparatus of the present invention, a switch section for selecting compression / non-compression of transmission data and a bit insertion section for giving a distinction between compression / non-compression are provided by a data monitoring control section.
Control is performed according to the data length notified from the TE side transmission buffer. At this time, if the data length is less than a specific number, the switch is automatically switched so as not to pass through the data compression unit, so even if short data blocks with poor compression efficiency are sent, do not pass through the data compression unit When the data length reaches a specific number, the switch is automatically switched so as to pass through the data compression unit, so that a normal compression effect can be obtained. As a result, regardless of the type (data length) of the transmission data, a throughput equal to or higher than the case where the data does not pass through the data compression unit can be secured.

[0010]

Embodiments of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing a basic configuration of a data network system according to an embodiment including a data compression device of the present invention.

This data network system has a DT
A data compression device 13 is provided between E1 and DCE 14, another data compression device 17 is provided between another DTE 18 and DCE 16, and the DCE 14 and DCE 16 are connected to the network 15. That is, the DTE 1 and the DCE 14 including the data compression device 13 are used here.
DTE 18 and DCE 16 including a data compression device 17
Therefore, only the configuration of the DTE 1 and the DCE 14 including the data compression device 13 will be described below.

The data compression device 13 here is a DTE1
A transmission buffer 2 for storing transmission data transmitted from the DTE as transmission storage data, a data compression unit 3 for compressing the transmission storage data with a specific algorithm to generate compressed data, and storing compressed data as transmission data. DCE
A transmission buffer 5 for transmitting to the DCE 14;
A DCE-side reception buffer 6 for storing transmission data transmitted from the receiver as reception storage data, a data decompression unit 8 for decompressing the reception storage data by a specific algorithm to generate decompressed data, and storing the decompressed data as reception data. DTE
And a DTE-side reception buffer 9 for transmitting data to the DTE 1.

Further, the data compression device 13 identifies the first switch unit 11 for switching and outputting the transmission accumulated data or the compressed data, and identifies the transmission accumulated data or the compressed data (uncompressed or compressed). A bit insertion unit 4 for adding an identification bit to the transmission accumulated data or compressed data to perform the first switch unit 11 when the data length is smaller than a specific number based on the data length of the transmission accumulation data. And a data monitoring control unit 10 for controlling the bit insertion unit 4 to add an identification bit to the transmission accumulation data while selecting transmission accumulation data.

The transmission buffer 2 on the DTE side notifies the data monitoring control unit 10 of the data length of the transmission accumulation data. When the data length exceeds a specific number, the data monitoring control unit 10 controls the first switch unit 1.
1 is controlled to select the compressed data, and the bit insertion unit 4 is controlled to add an identification bit to the compressed data.

Further, the data compression device 13 switches the received and stored data or the decompressed data and outputs the data, and monitors the received and stored data to determine whether the data is uncompressed or compressed based on the identification bit. In the case of non-compression, the discrimination bit is discarded and the second switch unit 12 is controlled to select the reception accumulation data.
An identification bit detection control unit 7 for discarding identification bits when compression is performed and then controlling the second switch unit 12 to select decompressed data is provided.

That is, in the transmission operation of the data compression device 13, the transmission data transmitted from the DTE 1
The ETE transmission buffer 2 accumulates the transmission accumulation data. The DTE transmission buffer 2 notifies the data monitoring control unit 10 of the data length of the transmission accumulation data before outputting the transmission accumulation data to the switch unit 11. Monitoring control unit 10
Then, the data length is determined.

Therefore, when the data length is smaller than the specific number L1 (for example, when the data length is less than 63 bytes), the data monitoring controller 10 activates the control signal for the switch unit 11 at that time as "1". . As a result, the switch unit 11 switches the switch to bypass the data compression unit 3 and connects the transmission accumulation data from the DTE-side transmission buffer 2 to the bit insertion unit 4. At the same time, the data monitoring control unit 10 activates a control signal for the bit insertion unit 4. As a result, the bit insertion unit 4 adds an additional bit (for example, “0”) for notifying that the data is not compressed,
To the side transmission buffer 5. Incidentally, the transmission data output from the DCE-side transmission buffer 5 is transmitted to the network 15 via the DCE 14, and thereafter, the DCE 1
6, the data is transmitted from the data compression device 17 to the DTE 18.

On the other hand, in the receiving operation of the data compression device 13, the transmission data transmitted from the opposite device via the DCE 14 is accumulated as reception accumulation data in the DCE side reception buffer 6, and is transmitted to the identification bit detection control unit 7. You. If the identification bit detection control unit 7 monitors the first bit of the received accumulated data before outputting the received accumulated data and detects “0”, it activates the control signal for the switch unit 12 and discards the additional bit “0”. Switch part 1
2 to select the output of the received and stored data so as to avoid the data decompression unit 8. As a result, the switch unit 12 switches the switch according to the active control signal to connect the received accumulated data to the DTE-side reception buffer 9. As a result, transmission data that has not passed through the data compression unit 3 can be prevented from passing through the data decompression unit 8 even on the receiving side.

By the way, in the transmission operation of the data compression device 13 described above, if the data length notified to the data monitoring control unit 10 is not less than a specific number L1 (for example, not less than 64 bytes), the switch at that time is The control signal for the unit 11 is set to "0" to make it inactive. Thus, the switch unit 11 switches the switch and connects the compressed data that has passed through the data compression unit 3 to the bit insertion unit 4. At the same time, the data monitoring control unit 10 makes the control signal for the bit insertion unit 4 inactive. As a result, the bit insertion unit 4 adds an additional bit (for example, “1”) to the head of the compressed data for notifying that the compression is performed, and then transmits the compressed data to the DCE side transmission buffer 5. By the way,
Also here, the transmission data output from the DCE-side transmission buffer 5 is transmitted to the network 15 via the DCE 14, and then transmitted to the data compression device 1 via the DCE 16.
7 to the DTE 18.

On the other hand, with respect to the receiving operation of the data compression device 13 in this case, the transmission data transmitted from the opposite device via the DCE 14 is accumulated as reception accumulation data in the DCE side reception buffer 6 and transmitted to the identification bit detection control unit 7. Transmitted. The identification bit detection control unit 7 monitors the first bit of the received accumulation data before outputting the received accumulation data to “1”.
Is detected, the control signal for the switch unit 12 is made inactive, the additional bit "1" is discarded, and then the switch unit 12 is controlled to output the received accumulated data, and the expanded data that has passed through the data expansion unit 8 is output. Let me choose. As a result, the switch unit 12 switches the switch according to the inactive control signal and connects the decompressed data to the DTE-side reception buffer 9. As a result, with respect to the transmission data that has passed through the data compression unit 3, the data expansion unit 8
Can pass through.

[0022]

As described above, the data compression apparatus of the present invention has a function of automatically controlling the compression / non-compression according to the data length of the transmission data from the DTE. Even if short data having a low data length is transmitted from the DTE, by avoiding the use of the data compression unit, it is possible to secure the same throughput as when no compression unit is used. As a result, no matter what kind of transmission data is transmitted from the DTE, a throughput equal to or higher than that when the data compression unit is not used can always be secured.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a data network system according to an embodiment including a data compression device of the present invention.

[Explanation of symbols]

 1,18 DTE 2 DTE side transmission buffer 3 Data compression unit 4 Bit insertion unit 5 DCE side transmission buffer 6 DCE side reception buffer 7 Identification bit detection control unit 8 Data decompression unit 9 DTE side reception buffer 10 Data monitoring control unit 11,12 Switch unit 13, 17 Data compression unit 14, 16 DCE 15 Network

Continuation of the front page (56) References JP-A-4-242424 (JP, A) JP-A-4-359315 (JP, A) JP-A-5-207178 (JP, A) JP-A-6-202845 (JP) JP-A-58-102314 (JP, A) JP-A-4-277981 (JP, A) JP-A-2-108119 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H03M 7/30

Claims (3)

(57) [Claims] 1. A data terminal device-side transmission buffer that stores transmission data transmitted from a data terminal device as transmission storage data, a data compression unit that compresses the transmission storage data with a specific algorithm to generate compressed data, A data line termination device-side transmission buffer for storing the compressed data and transmitting it as transmission data to the data line termination device; and a data line termination device-side reception buffer for storing transmission data transmitted from the data line termination device as received stored data. A buffer, a data decompression unit that decompresses the received accumulation data by the specific algorithm to generate decompression data, and a data terminal device-side reception buffer that accumulates the decompression data and transmits the decompression data to the data terminal device as reception data. Switching between the transmission accumulated data or the compressed data in the data compression device provided with A first switch unit for outputting the data, a bit insertion unit for adding an identification bit for identifying the transmission accumulated data or the compressed data to the transmission accumulated data or the compressed data, and a data length of the transmission accumulated data. And when the data length is smaller than a specific number, the first switch unit is controlled to select the transmission storage data, and the bit insertion unit is controlled to control the transmission storage data so that the identification bit is added to the transmission storage data. And a data monitoring control unit for adding the data storage device, wherein the data terminal device-side transmission buffer notifies the data monitoring control unit of the data length of the transmission accumulation data. 2. The data compression device according to claim 1, wherein the data monitoring control unit controls the first switch unit to select the compressed data when the data length becomes a specific number or more. A data compression device that controls the bit insertion unit to add the identification bit to the compressed data. 3. The data compression device according to claim 1, wherein a second switch unit for switching and outputting the received accumulated data or the decompressed data, and monitoring the received accumulated data based on the identification bit. It is determined whether the data is uncompressed or compressed. If the data is uncompressed, the identification bit is discarded and the second switch unit is controlled to select the received and stored data. An identification bit detection control unit that discards the identification bit and then controls the second switch unit to select the decompressed data.