JP3008635B2 - Data communication 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 communication device having a data compression function.

[0002]

2. Description of the Related Art There are various data compression methods, and a data communication device having a data compression function based on the technology is also known. For example, an algorithm for compressing character string data and a technique for providing the data communication device with the algorithm include CCITT Recommendation V.1. The method shown in 42bis is a typical example. Although the description of this method itself is omitted, by this method, the mutual data communication apparatuses have information indicating the relation between the same character string and the index (this is called a dictionary), and the symbol examples are changed to the index. Transmit. At this time, the index
It depends on whether the character string is one index.
However, the index length uniquely determines the character string.
Therefore, the data is 9 bits or more. This
The same data communication equipment
A dictionary defines a character string according to a rule.
3 characters (24 bits) indexed to a specific 9 bit
The sender of data can use this dictionary
To convert specific 24-bit data to 9-bit data based on
After conversion, the data receiving side converts the specific 9-bit data into 2 bits.
It can be converted to 4 bits and regarded as the original transmission data.
In this way, mutual data communication devices can use a common dictionary
By having this, data communication with an information length shorter than the information actually desired to be transmitted is enabled.

Here, CCITT Recommendation V. In the case of 42bis, the character string indexed at the start of data communication is a character string having a character string length of 1 using all 8-bit codes, except for a unique control index, and thereafter appears in transmitted data. The method of registering the character string to be performed in the dictionary is adopted. A data communication apparatus having a means for realizing this method assigns an index to a character string in the process of transmitting data, and transmits the index when the same character string appears again, thereby increasing the index. The transmission of the compression ratio is realized.

[0004]

The problem with the above method is that the dictionary stored at the start of data communication is composed only of characters of all 8-bit codes. This indicates that the data compression ratio at the beginning of data communication is inferior to that after data communication has been performed to some extent, and therefore, what data is transmitted. For a user of a data communication device who knows what to represent or knows in advance, the compressed data is not difficult to guess at some of the strings that appear frequently in the data to be transmitted. This indicates that the data transmission amount is increasing at the beginning of data communication.

A first object of the present invention is to provide a data transmission amount,
Eventually, in order to reduce the transmission time and the line cost in data communication, the data communication with the same data communication partner is repeated.
When performing data communication, a newly appearing character string is registered in the dictionary based on a dictionary created by the previous data communication and already having an index for a certain number of character strings. An object of the present invention is to provide a highly efficient compressed data communication apparatus from the start of data communication.

In a data communication apparatus having a function to achieve the first object, when the storage capacity of a storage device is finite, data for storing various types of dictionaries as long as the storage capacity permits. A second object is to provide a data communication device.

[0007]

Means for Solving the Problems The present invention, in order to achieve the first object, the user is de to be transmitted - de has a function of transmitting to compress the data - and data communication apparatus main body, the Book
It is stored in the body and the mutual data communication device is the same character string
A plurality of dictionaries having information related to the index;
Appeared in the data group used in the data communication
These words indexing multiple strings
One of the documents is the destination address and keyword for data communication.
Is added as additional information to a specific dictionary,
De dictionary - after data communication end also stores a storage means, de - data
When starting communication, use the above partner address and keyword
The data communication device stores the same specific dictionary.
Using the means to confirm whether or not
Whether to start data communication by data compression
And data compression using the specific dictionary.
It is provided with means for performing data communication .

Further, the present invention relates to a specific dictionary stored by a storage means in order to achieve the second object.
Address and keyword stored as additional information
Are stored in the storage device, but the same dictionary
A dictionary that is the same when it is possible that
And a specific word that is the same as a result of this search
Each document is stored as additional information
Regarding the destination address and keyword as one related information
And add each one to only one specific dictionary
Information is stored in the storage device, and the remaining dictionaries are stored in the storage device.
It is provided with a means for deleting from the location .

Therefore, according to the present invention, a dictionary used for a certain data communication is set as a specific dictionary, stored even after the data communication is completed, and when the same communication is performed again, the same dictionary is used.
After confirming that the specific dictionaries are mutually stored, the data communication using the specific dictionaries from the start of the data communication is realized. In addition, by storing a plurality of same dictionaries having different partner addresses and keywords as having only one dictionary (specific dictionary) and additional information based on a combination of a plurality of partner addresses and keywords, storage in the storage device is performed. Capacity can be used efficiently.

[0010]

FIG. 1 shows the configuration of an embodiment of the present invention.

In FIG. 1, reference numeral 1 denotes a storage device, which is a dictionary 11 used during data communication.
And the dictionary 12 used in the previous data communication.
Reference numeral 2 denotes a device for generating a dictionary, and reference numeral 3 denotes a device for storing a dictionary 11 as a dictionary 12, a partner address of data communication,
A device 4 for storing the word as additional information; a device 4 for comparing the address of the data communication at that time with the address of the data communication stored as the additional information in the dictionary;
Is a device for confirming a keyword, and 6 is a device for determining whether or not to transmit data by a data compression function using a stored dictionary. Reference numeral 7 denotes a device for searching the same dictionary from a plurality of dictionaries 12, and reference numeral 8 denotes a destination address and a keyword, which are additional information of the searched dictionaries, as additional information of only one of the dictionaries. An apparatus 9 releases an area storing the rest of the dictionary to be searched from the storage device.

In FIG. 1, a solid line represents a data transmission / reception system, and a broken line represents a control line between devices.

Next, the operation of the above embodiment will be described. First, a dictionary 1 to which an index is added each time data is transmitted by the dictionary generation device 2 during data communication.
No. 1 is stored in the additional information storage device 3 as a specific dictionary 12 having a fixed index, and the partner address and the keyword are stored as additional information. This operation is desirably performed simultaneously by the users of the mutual data communication devices when it is guaranteed that no data is transmitted. If the users of each other's data communication device perform this operation independently and at any time, the transmitting data communication device transmits which character string and then performs this operation. This is because the data communication devices cannot recognize the same specific dictionary.

FIG. 2 is a diagram showing a dictionary 12 stored in the storage device 1 by the dictionary generation device 3 with information of a partner address 13 and a keyword 14 added thereto. Here, the reason for storing two of the partner address and the keyword as additional information will be described below.

First, when storing only keywords,
It is difficult to select a completely new keyword for each of different data communication partners each time. When storing only the address of the other party, only one dictionary can be stored for the same party. This eliminates the versatility of frequently transmitting data from the same partner and completely different dictionaries.

Next, when the data communication is performed again, the comparison device 4 compares the data communication partner address with the partner address information added to the dictionary 12. At this time, if a plurality of dictionaries are stored, there are a plurality of partner address information, and the respective partner address information is compared. As a result of the comparison, if there is matching partner address information, the dictionary associated with the information may have been stored when data communication was previously performed with the same partner.

Here, there is a possibility that there are a plurality of dictionaries having the same address information, and there is a possibility that the data communication device of the other party has discarded the previously stored dictionary by some method. To solve the above problems, keywords have an effective effect.

The confirming device 5 transmits the keyword added to the dictionary selected by the operation of the comparing device 4 to the other party before using the data compression function in the data communication. At this time, in mutual data communication equipment,
One example of notifying that this information is a keyword is that when data communication is performed, the first information transmitted is the keyword information, which is mutually agreed upon. Here, when a plurality of dictionaries are selected for the data communication partner, the user of the data communication device selects one of the plurality of keywords and transmits the keyword. Therefore, the comparison device 4 notifies the user of the data communication device of the keyword associated with the dictionary that can be used in the data communication, and thereby, the dictionary associated with the keyword selected by the user of the data communication device ( It also has a function to reselect a specific dictionary .

The confirmation device 5 receives the keyword transmitted by the data communication device of the other party, and receives the keyword from the dictionary 12 selected by the comparison device 4.
Select the same keyword (specific dictionary) . This operation allows the data communication device to respond in some way to the possibility that the previously stored dictionary has been discarded. That is, the keyword is the additional information storage device 3
, The absence of the keyword received by the above operation indicates that the dictionary 12 associated with the keyword is discarded by some method. Therefore , the checking device 5 has a function of transmitting information indicating that data cannot be transmitted by data compression using an existing dictionary by the determining device 6 when the same keyword does not exist.

Further, in actual data communication, it is the user of the data communication device that determines to transmit data by data compression. Here, if the user of the data communication device that has received the keyword does not intend to transmit data by data compression using an existing dictionary, this is indicated using the determination device 6 in some way. Instead of transmitting information or transmitting the above-described keyword, the determination device 6 transmits information indicating that there is no intention to transmit data by data compression using an existing dictionary.

If the above operation is performed by each of the data communication devices that perform the data communication, and this dictionary is used immediately after the start of the data communication, the effect is as follows.
It becomes possible to transmit data at a high compression rate.

In the above description of the operation, if the storage device for storing the dictionary has an infinite capacity, the dictionary used once in the data communication may be stored one after another. However, if the storage capacity is finite, there is a limit to continuing to store one after another. Therefore, a function for effectively utilizing the storage capacity is required.

Here, it is considered that when a dictionary is generated between a plurality of data communication devices, the same dictionary may be stored. Here, in practice, it is not necessary to store each dictionary individually, the content of the dictionary itself is one, and it is sufficient if a set of the address and the keyword of each data communication device is added to this dictionary. It is.

In order to solve the above problem, first, the search device 7 searches the dictionary 12 having the same contents. Since various search methods are conceivable, they are omitted here.

FIG. 3 is a diagram showing a dictionary group searched by the search device 7. In FIG. 3, reference numerals 121 to 123 denote dictionaries stored by the additional information device 3 and 131 to 13.
Reference numeral 3 denotes partner address information added to the dictionaries 121 to 123 by the additional information storage device 3, and 141 to 143 denote keywords added to the dictionaries 121 to 123 by the additional information storage device 3.

The additional information storage device 8 associates, as a set, the information of the partner address and the information of the keyword having a relationship with each other for each of the plurality of dictionaries regarded as having the same contents by the above operation. . Thereafter, an arbitrary dictionary is selected, and a set of information on the address of the other dictionary and information on the keyword is associated with the dictionary.

After the above operation is completed, the release device 9 releases the storage area allocated by the storage device 1 for the remaining dictionaries.

FIG. 4 is a diagram showing the dictionary group of FIG. 3 newly stored in the storage device 1 by the devices 8 and 9. Compared to the figure, the usable storage capacity of the storage device 1 has increased due to the deletion of the dictionaries 122 and 123.

By performing the above operation, it is possible to increase the number of types of the specific dictionary that can be stored as much as possible by minimizing the area allocated for storing the contents of the dictionary within the limited storage capacity. Becomes

[0030]

According to the present invention, as is apparent from the above embodiment, when data communication is performed with the same partner, what the data to be transmitted represents is determined by the user of the data communication apparatus. If it is known in advance, once the data communication device user determines that the data compression rate is higher when using the dictionary used for data transmission once, it is set as a specific dictionary, and the specific dictionary is used immediately after data communication starts. By using
It is possible to transmit data with a high compression rate,
It is possible to reduce the amount of data transmission, and thus the transmission time and the line cost in data communication, as compared with a data communication device using a conventional character string data compression method.

Further, according to the present invention, when the storage capacity of the storage device is finite, it is possible to store various types of specific dictionaries in the storage device, and the above function can be performed for a large number of partners. Data communication using can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of a data communication device according to an embodiment of the present invention.

FIG. 2 is a diagram illustrating a dictionary in which information of a partner address and a keyword is added to the dictionary by the additional information storage device according to the embodiment;

FIG. 3 is a diagram illustrating a dictionary group searched by a search device according to the embodiment;

FIG. 4 is a diagram showing a dictionary group newly stored on a storage device by an additional information storage device and a release device according to the embodiment;

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 storage device 2 dictionary generation device 3 additional information storage device 4 comparison device 5 checking device 6 judgment device 7 search device 8 additional information storage device 9 release device 11, 12 dictionary 13 partner address information 14 keyword 121 to 123 dictionary 131 to 133 partner Address information 141-143 Keywords

Claims (2)

(57) [Claims] 1. A data communication apparatus main body having a function of compressing and transmitting data desired by a user and a data communication apparatus housed in the main body and having the same data communication apparatus.
Multiple dictionaries with related information of strings and indexes
If there de - de used in data communication - these were indexed to a plurality of symbol strings that appeared in the other groups
One of the dictionaries includes a destination address and a key for data communication.
Is added as additional information to a specific dictionary.
Storage means for storing the data in the fixed dictionary even after the end of data communication; and
Means for confirming whether or not the data communication apparatus stores the same specific dictionary by means of a word; and starting data communication by data compression using the specific dictionary. A data communication apparatus comprising: means for selecting whether or not to perform data communication; and means for performing data communication by data compression using the specific dictionary . 2. A specific dictionary stored by a storage means is different from a partner address and a keyword stored as additional information, but a plurality of same dictionaries are stored in a storage device. Means for retrieving the same dictionary when there is a possibility that the same dictionary has been searched; and for the same specific dictionary as a result of the search, the partner address and key stored as additional information respectively.
Means for treating words as one piece of related information, storing each word as additional information for only one specific dictionary in a storage device, and deleting the remaining dictionary from the storage device. The data communication device according to claim 1.