JP2003346284A - Compression-encoding transmitter for road traffic information, depression-decoding receiver therefor, compression-encoding transmission method therefor, and depression-decoding reception method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a remarkably high compression effect for a compression rate expected in compression encoding of road traffic information. <P>SOLUTION: This compression encoding transmitter has an encoding means 21 for encoding the road traffic information to generate encoded information, and a compression means 50 for compressing the encoded information to generate a compressed code. The encoding means 21 is provided with a spreadsheet type data table preparing means 25 for receiving the road traffic information, for rearranging the compression encoding to be readjusted, and for preparing a spreadsheet type data table, an item-by-item data characteristic extracting means 27 for analyzing a data characteristic of the spreadsheet type data table an item by an item to extract it, and an encoding system selecting means 29 for selecting a prescribed encoding system having a correlation of the compression effect to the spreadsheet type data table to generate the encoded information. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to compression coding, and more particularly, to a compression coding transmission apparatus for road traffic information, a decompression decoding reception apparatus thereof, a compression coding transmission method thereof, and a decompression decoding reception method. It is.

[0002]

2. Description of the Related Art There is a demand for transmission of a larger amount of information to a user of a mobile unit related to this kind of road traffic information, but a VIC related to the road traffic information provided by the applicant for the mobile unit.
In a limited transmission path such as the S link, the amount of information is limited, and it takes time to send a large amount of information. On the other hand, if a wide transmission path is used, a large amount of information can be obtained, but the cost is high.

[0003] For the above reasons, as a conventional example which has a compression effect of compression coding in order to convert an information amount into a compressed small amount and transmit it in a short time, see Japanese Patent Application Laid-Open No. 8-340.
No. 257 discloses an FM multiplex information processing apparatus and method.

[0004]

However, in the conventional example, the compression effect of the compression coding of road traffic information cannot be expected so much, and a large amount of road traffic information cannot be transmitted.

Accordingly, a technical problem of the present invention is to provide a road traffic information compression-encoding transmission apparatus which can expect a particularly high compression effect with a high compression ratio of road traffic information and can transmit a large amount of road traffic information. An object of the present invention is to obtain the decompression decoding receiving apparatus, the compression encoding transmission method, and the decompression decoding reception method.

[0006]

According to the present invention, there is provided a road traffic information compression-encoding transmission apparatus for transmitting road traffic information in the form of a compression code. The apparatus has encoding means for encoding the road traffic information to generate encoded information, and compression means for compressing the encoded information to generate the compression code. Means for receiving the road traffic information, rearranging and organizing the road traffic information, and preparing a tabular data table for preparing a tabular data table; Itemized data feature extraction means for analyzing and extracting;
Coding means for selecting a predetermined coding method having a correlation of a compression effect with respect to the tabular data table and generating the coding information; Is obtained.

A decompression decoding receiver for road traffic information for receiving and decompressing and decoding a compression code of road traffic information, wherein the decompression decoding receiver decompresses the compression code and encodes it. Decompression means for generating information, and decoding means for decoding the encoded information into the road traffic information, the decompression means receives the itemized data decompressed the compression code, A decompression decoding receiving apparatus for road traffic information is provided, comprising an encoding method determining means for determining an optimal encoding method for the data feature of the item-specific data.

Further, there is provided a road traffic information compression-encoding transmission method for transmitting road traffic information in the form of a compression code, wherein the compression-encoding transmission method encodes the road traffic information to generate encoded information. An encoding step for generating, and a compression step for compressing the encoded information to generate the compression code, wherein the encoding step receives the road traffic information and converts the road traffic information to A tabular data table creation step for rearranging and organizing and preparing a tabular data table; an item-by-item data feature extraction step for analyzing and extracting data features of the tabular data table by item; A coding method for selecting a predetermined coding method having a correlation of the compression effect with respect to the tabular data table and generating the coding information. Compression coding method for transmitting through information is obtained.

In addition, there is provided a decompression decoding reception method of road traffic information for receiving and decompressing decoding of a compression code of road traffic information, wherein the decompression decoding reception method decompresses the compression code, And a decoding step for decoding the coded information into the road traffic information. The decompressing step receives the itemized data obtained by decompressing the compression code. And a decoding method for decompressing and decoding road traffic information, comprising a coding method determining step for determining an optimum coding method for the data feature of the item-specific data.

[0010]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing the configuration of an apparatus for compressing / encoding road traffic information according to the present invention; Will be described in detail. (Compression coded transmission device for road traffic information)

The apparatus for compressing and encoding road traffic information of the present invention shown in FIG. 1 is arranged in a VICS center 15 where road traffic information can be obtained for each VICS link, and detects a large number of beacons and the like installed on the road. The information is input to the road traffic information input means 17 in the VICS center 15 through the device 11 and the road traffic information generating means 13 of each police. The compression-encoding transmission device has an encoding unit 21 for encoding road traffic information to generate encoded information, and a compression unit 50 for compressing the encoded information to generate a compression code.

The encoding means 21 receives the road traffic information,
Tabular data table creating means 2 for rearranging and organizing road traffic information and preparing a tabular data table
5, item-by-item data feature extraction means 27 for analyzing and extracting data features of the tabular data table by item;
A coding method selecting means 29 for selecting a predetermined coding method having a correlation of the compression effect with respect to the tabular data table and generating coding information; Data compression preprocessing means 39 for preprocessing desired data among the information.

The predetermined coding methods of the coding method selection means 29 include a flag data coding method 31, a variable bit length data coding method 33, and a run length coding method 3, which will be described later.
5 and Huffman coding system 37.

The data features include the number of data, the distribution bias,
And at least one of the number of bits constituting the bit string.

The data compression preprocessing means 39 receives two of the data features, determines whether or not the corresponding bit strings of the data features match, and generates a bit string match signal indicating the matching of the corresponding bit strings. And a non-coincidence identification means 4 for generating a non-coincidence bit number signal indicating a non-coincidence bit number among the bit strings corresponding to the data characteristics and identifying the data characteristics.
3, a bit position exchanging means 45 for exchanging the positions of the bits of the bit string representing the data characteristics, and an item-specific data reorganizing means 47 for reorganizing the data characteristics for each item.

The coincidence judging means 41 shown in FIG. 16 receives two data features in order, shifts the preceding data feature twice to generate the preceding data output signal, and compares the latter data feature with one.
A pair of shift registers 1 and 2 for generating a data output signal after a double shift, and a data adding means for adding the data outputs to each other to obtain an exclusive OR (EXOR) of two data characteristics (1 bit adder). (Decompression decoding receiver for road traffic information)

The apparatus for decompressing and decoding road traffic information according to the present invention shown in FIG. 36 is mounted on a mobile body, and receives and decodes decompressed codes of road traffic information. The decompression decoding receiving device includes a decompression unit 75 for decompressing a compression code and generating encoded information, and a decoding unit 81 for decoding the encoded information into road traffic information.

The decompressing means 75 includes an encoding method judging means 77 for receiving the itemized data obtained by decompressing the compression code and judging the optimum encoding method for the data characteristic of the itemized data.

The decoding means 81 receives the coded information, and receives the coded information into a predetermined coding system comprising a flag data coding system 85, a variable bit length data coding system 87, a run length coding system 89 and a Huffman coding system 91. An encoding scheme restoring unit 83 for restoring one of the encoding schemes as being optimally selected, and an item for reproducing an item-specific data from the encoding information when the encoding scheme is selected. By referring to tabular information prepared in advance from the separate data reproducing means 92, the individual data reorganizing means 93 for reorganizing the individual data, and the tabular information supply means 95, the road traffic information is obtained from the individual data. And a tabular data table creating means 97 for reading and creating a tabular data table in which information is arranged. The tabular information prepared in advance is a tabular data table created by the tabular data table creating means 25 on the transmitting side in FIG. (Method of compressing and encoding road traffic information)

Referring to FIGS. 1 to 35, a method for compressing and encoding road traffic information according to the present invention will be described. The technical features of the compression coded transmission method are listed below.

The data is preprocessed item by item to produce data having the highest compression effect, and this is encoded using an encoding preprocessing step (see FIG. 3) that matches the data characteristics, that is, data characteristics. (Encoding process 2
1).

In order to minimize the compression code, the data is divided by increasing or decreasing the number of bits representing a series of data, data is created as to whether it is better to insert the data, and the data is compared to apply a data having a high compression effect.

One-bit data such as extension data is directly compressed in a flag format.

In a data group including data other than “0” and “0”, the data is once divided into other than “0” and “0”, and data other than “0” is set to “1” to generate flag-format data. Then, the data corresponding to "1" is compressed by the variable bit method.

For the secondary mesh number, the codes in the data are rearranged to ensure continuity.

1. Data characteristics and compression process

The traffic congestion information using the VICS link has its data represented for each link. In general, in order to compress data, good correlation with previous data is required.

However, the method of arranging the data for each link has a poor correlation with the previous data.
A compression method (encoding means (step) 21 preceding the compression means (step) 50 of FIG. 1) which matches the characteristics of the data, that is, the data characteristics, is used for each item.

FIG. 2 is a table showing the congestion information as an example of the road traffic information according to the present invention. These will be examined for each item and the optimal compression method will be described. FIG. 3 is a table showing the data items and the pre-encoding means employed.
Hereinafter, the encoding means 21 which is the preceding means of the compression means 50 will be described in detail for each of the items 1.1 to 3.4.

1.1 Secondary mesh, link distinction The secondary mesh number has substantially the same contents, and the link division is for each information source. Therefore, the link division may be specified only once. Although there are a plurality of secondary mesh numbers, there is a link number for each secondary mesh, so it is necessary to indicate the number of links. The entire compressed data structure is as shown in FIG.

FIG. 5 shows the bit position replacing means 45 for secondary mesh data, that is, the data converting means. In this way, mesh data from the first mesh data is configured. Subsequently, data of the number of links is entered for each mesh. The data thus generated is encoded by a data compression method.

In FIG. 4, the first secondary mesh number is 16 bits since it is full data, and the next link section is represented only by one bit since it is performed only once. The second and subsequent mesh numbers have a smaller number of digits because they are differences between the numerical values rearranged as described above. After the secondary mesh, each 2
Data on the number of links in the next mesh is entered. Difference 2
The next mesh and the number of links are collectively compressed as a series of data by a data compression method described later.

1.2 Link Number Referring to the data format of the link number shown in FIG. 6, the link numbers are generally arranged in ascending order. EXOR.

By doing so, the data of "0" increases. First, the data is divided into “0” and non-zero numerical values, and the data is encoded by the flag compression method. Next, non- "0" portions are collected and encoded by a data compression method (variable length bit method and synonym).

1.3 Congestion Degree Information Referring to FIG. 7, although the congestion degree is 2-bit data, since the distribution is uneven, a variable-length code provides a compression effect. As data processing, the result obtained by taking the exclusive OR EXOR with the previous data is processed by Huffman coding.

1.4 Extension and Congestion Length Information As shown in FIG. 8, the extension flag is encoded by a flag compression method. Next, since there is data in the "1" portion of the extension flag information, this portion is extracted and the congestion length data is encoded in a data compression format. In this case, the codes "111 ... 1" are converted to -1 and "11 ... 10" are converted to -2 in the preprocessing.

1.5 Extended Top Position Information Referring to FIG. 9, this is flag information of the extended information dealt with in the previous section on the congestion length, and data is present only in the "1" part. This data is divided into “0” and other than “0”, flag information is created, and encoded by the flag compression method. Next, data other than "0" is extracted and encoded by a data compression method.

1.6 Travel Time Information Referring to FIG. 10, since the link travel time is not always present in all links, flag information indicating the presence / absence of the link travel time, ie, extended information, is generated and encoded by the flag compression method. I do.

In the flag "1", information of the maximum value "111... 1", which means time is unknown, and information which is not, are encoded by the flag compression method. Finally, the information remaining in the flag is encoded by a data compression method.

1.7 Real Time / Measurement Time, Aggregated Information Referring to the data format of FIG. 11, when the link travel time flag is “1”, the real time / measurement time flag is set. Information, and when it is "0", it is aggregated information. Using these characteristics, the two are combined. At this time, if the aggregated information is reversed, “0” is overwhelmingly increased. The information thus generated is encoded by a run-length method. Here 8 bits (fixed) to indicate the length of the run
Shall be taken. First, one bit indicates “0” or “1”, and eight bits indicate its length. If the length cannot be represented by 8 bits, it is represented by 255.

1.8 Compression Effect (Overall Effect)

Referring to the rightmost column of FIG. 12, according to the present invention, data indicating the compression ratio for each item is listed, so that a remarkable compression effect can be expected. As described above, the compression rate can be reduced to 27.2% compared to the fixed table format of the binner, so that an extremely high effect can be obtained. 2.13 per link
Bytes. In Kanagawa, it is 2.33 bytes, Tokyo Metropolitan Area 1.70 bytes, Tomei Expressway 1.59 bytes.

More specifically, a remarkable compression effect can be obtained in that the traffic can be compressed to 10% or less as compared with a case where the road traffic information is described in XML and not compressed.

1.9 Range of Application As will be described repeatedly, the compression step of the present invention can be expected to have an extremely large compression effect on data including fixed data and extended data expressed in a table format. Since various data can be represented in a tabular format, the application range is wide. In this embodiment, traffic congestion information is used, but other event regulation information,
Parking lot information, service area information, section travel time information,
Sightseeing information, public transport information, hotel restaurant information, event information, weather information, etc.

It is assumed that the tabular data includes a fixed information item and an optional blank item. Of course, it is possible even when there are no optional items.

2 Evaluation of compression method 2.1 VICS link number

The VICS link numbers are generally in ascending order, but the link travel time is aggregated, the link numbers are updated, and the order is not always constant. However, when they are continuous, they are increasing one by one, and this case is common.

First, as pre-processing, 1 is added to the immediately preceding link number, and exclusive OR (EXO
R) Take. As a result, 0 data increases. The compression is examined using this characteristic.

The data obtained as a result of the above processing and the data used are 10:12 on June 15, 2001, and are on Tokyo General Road.
In the following, this data will be considered unless otherwise specified. The distribution of numbers following “0” is shown in the table below. The upper row is the number following "0" and the lower row is the frequency.

In this data, “1” is 1735,
“0” is 4128−1735 = 2393.

[0051]   1735 + 381 x 1 + 98 x 2 + 88 x 3 + ... = 4128 (number of links) When assigned by Huffman code Only 1 bit representing “1” Only 2 bits representing "2" : : N bits only for “n” When the distribution in the above table is calculated, it becomes 2393 bits.

Incidentally, the number of cases other than "0" is 1735, and the sum thereof is 1735 + 2393 = 4128 links. I was asked
2393 is the sum of consecutive numbers of “0”.

This numerical value is the minimum value representing the length.
If there is a bias in the distribution, there is a possibility that it can be further reduced.
However, if this link number difference data is averaged, it proceeds in a direction without bias. Therefore, even if the Huffman code is used, there is no compression effect.

Method of Representing with Length of "0" (Run Length)
Now consider the amount of information. The length of "0" is represented by 3 bits using 1 to 7, and when it is 8 or more, it is divided into 1 to 7 and used repeatedly. The result is 2643 bits. This is not better than the Huffman code, which represents the length of "0". When there is no bias, it is the same as the case where “0” and “1” are directly expressed. (Examination of fixed length format)

The link number has a maximum value of 4 using 12 bits.
095, but can also be expressed separately. Since it is considered that the number of the divided units often takes “0”, the case of 12 bits, 6 bits, 4 bits, and 3 bits will be examined. In calculating the information amount, 4128 bits are required (flag format) to indicate whether it is “0” or a numerical value over the entire number of links. The numerical value is the number of divided bits.

The frequency distribution in this case is as shown in the following table.
There are 1735. Numeric data 1735 requires 12 bits, so the total is 1735 x 12 + 4128 = 24948 (3118 bytes)

[0057] In units of 4 bits 3468 is a numerical value and (4128 × 3−3468) = 8916 is “0”. Information amount = 3468 x 4 + 4128 x 3 = 22785 (2848 bytes)

[0058] In units of 3 bits, Information amount = 4081 × 3 + 4127 × 4 = 28751 (3593 bytes)

[0059] 6-bit unit Information amount = 2633 x 6 + 4127 x 2 = 24052 (3006 bytes)

The above results are summarized as shown in FIG. From this result, it can be seen that the method of dividing into 4 bits is the best. (Link number distribution and data volume)

Further, the following method is studied. EXOR
The distribution of the link numbers after the processing is as shown in FIGS. The numerical value is a frequency ranging from the numerical value of the preceding term to the numerical value of the term.

The meaning of this table is that there are 2393 “0” s.
89 are "1" and 130 are 2-3, that is, 89 can be represented by 1 bit, 130 can be represented by 2 bits, and 148 can be represented by 3 bits.・
... Since the data is considered to come out at random, if the code length is given to each data, the whole data amount will be increased. Therefore, it is considered to divide into at least two.

When the code format is divided into, for example, 63 or less and 64 or more, it is shown in the upper part of FIG. The number of data from 1 to 63 for calculating the information amount for these two cases is 808 from the table. 64 or more: 927 1-255 from 1111, 256 or more: 624 6 × 808 + 12 × 927 = 15972 bits 8 × 1111 + 12 × 624 = 16376 bits

As a result, it is understood that the method of dividing the data into 1 to 63 and 64 to 4095 is preferable. 15972 when the flag is added
+ 4128 = 20100 (2513 bytes).

In the data, there is no value between 2048 and 4095.
12 bits can be represented by 11 bits. To take advantage of this property, another level division is needed. It is problematic to add another bit for leveling, so there is a way to define the range of data. It is desirable to divide according to the characteristics of the data. As a division method, it can be said that division in which the range where the maximum value is small is wide and the range where the maximum value is small is increased as a whole enhances the compression effect.

In the above examination, in the case of a link number, processing is performed as follows. This method can also be applied to traffic jam length, head position, and travel time.

The link number is added to the previous value by 1, and EXO is added.
Take R and increase the data of "0".

It is divided into “0” and other than “0”, and other than “0” is 1
The data in the flag format is 1 bit for each link,
Make all links.

When the above value is other than "0", it is necessary to represent a numerical value. The number of bits is determined by the maximum value of the numerical value.

To represent a numerical value, two levels are divided.

All data is appropriately divided, an optimum bit length is allocated, and useless bits are eliminated as much as possible.

The data format is as follows. When this method was used with link data, the following values were obtained.

[0073] Value range 0 to 2631 Maximum bits 10 Level division 64                2632 to 3580 Maximum bits 11 Level division 64                3581 ~ 4127 Maximum bit 12 Level division 128

The result was that the information amount was 2326 bytes for the number of links 4128. This result is obtained when the two levels are fixed (25
12 bytes) better result. Referring to FIG.
In this data format, a part that handles data in the flag format is called flag compression, and a part that handles data part is called data compression.

2.2 Compression Method of Congestion Degree The congestion degree is represented by 0, 1, 2, and 3 representing 2 bits. When this item is EXORed with the previous data, “0” increases.
In this case, the number may be divided into a number following “0” and numerical values 1, 2, and 3. As a result of processing the data with a run length bit number representing “0” of 2 bits, the compression effect is 975 bytes and the compression effect is 94.4% compared to 4128 × 2.

Referring to the table showing the bit length representing "0" of the degree of congestion in FIG. 26, it can be understood from this result that the length representing "0" is preferably 2 bits (1, 2, 3). .

Since the compression rate is not good in the method shown in FIG. 26, a method having a higher compression rate shown in FIG. 27 will be examined.
First, the characteristics of the data, that is, the distribution of the data are examined and analyzed. Since the degree of congestion is 0 to 3, the result of obtaining this frequency distribution is shown in the congestion degree distribution table of FIG. 27, and is a value obtained by taking an EXOR of the original data and the previous data. Are listed. This assessment was made on June 15, 2001.
At 10:12 on the day of Tokyo General Road.

As shown in FIG. 28, four kinds of codes are created as variable length codes. Calculate the amount of information about link 4128. Fixed length 4128 x 2 = 8256 bits Original data variable length 2641 x 1 + 1272 x 2 + 215 x 3 + 0 x 3 = 5830 70.6% EXOR variable length 2759 x 1 + 1082 x 2 + (105 + 182) x 3 = 5784 70.0% As a result, the variable length code (Huffman It can be seen that the compression effect can be obtained more with (sign). Raw data and EXOR
The difference is small.

2.3 Traffic Jam Extended Information The extended information of the traffic jam information is 20 to 30% of the whole. When the flag is "1", the extended information has a value indicating the congestion head position and the congestion length. First, the diagram showing the distribution of the flag of the traffic jam information in FIG. 14 is examined.

In the table of FIG. 14, the frequencies following "0" are shown. As a result, since there is not much bias, the effect of using the tunable code is small. If a modulatable code is used,
Since information is required in a header portion that defines the code, if the amount is converted, it can be said that the effect of the tunable code is not at such a data amount.

(1) Traffic Congestion Leading Position Since the leading position of the traffic congestion is about half "0", this part is also treated as a flag. It should be noted that the extension flag is not put here, but put in the place of the traffic jam length. There are 374 data, the level is 128, and the maximum bit is 9. The result is 509 bytes.

(2) Traffic Congestion Length The number of extension flags “1” in the traffic congestion information is 951, which is the maximum traffic congestion length.
The bit length is 8, and the level is 64. The result of this coding is 1426 bytes.

2.4 Link Travel Time The distribution of link travel time extension flags is as shown in the table of FIG. Since there is no bias in this flag data, coding is performed for all links as they are. The link travel time is set only when the extension flag is “1”. Total data amount is 2718
Thus, the maximum number of bits is 13, the level is divided into 1024, and the total information amount is 4274 bytes.

Next, 1-bit information includes actual / measurement and aggregation. Actual / measurement is when the extension flag is “1”, and aggregation is when the extension flag is “0”. The actual / measured data is almost “0” and the aggregation is almost “1”. Extended flag “1” as data
Link takes travel time, and when it is "0", it aggregates and inverts "1" and "0". This is almost “0”
Is the data that follows. The representation of this data is “0”
Is suitable.

3. Explanation of compression method 3.1 Pre-processing (EXOR)

The circuit shown in FIG. 16 includes an exclusive OR circuit (EXOR) used for preprocessing of compression. First, data is input by the shift register 1. Shift register 1
Are shifted in response to a clock shift signal, and one bit output from the shift register 1 is input to the shift register 2. The output of the shift register 1 and the output of the shift register 2 are added by an adder, and the result is input to the shift register 3. In this adder, a 1-bit operation is performed,
If both are 1, then it will be 2, but it will be 0 since there is only one bit. The first operation clears the shift register 2 and the shift register 3 with a clear signal.

The next data is input to the shift register 1. After that, when a clock is input by the number of bits, the first data is output to the shift register 3. Further, when a clock having the number of bits is input, the first data and the second data are EXORed and output to the shift register 3. Thereafter, the same processing is performed to generate EXOR data.

3.2 Data Compression Method As a method of creating data in which numerical values are compressed for each item,
"0" and non- "0" data in flag format are converted to flag format
One bit represents one data, and all data are set in advance.

Next, one or more pieces of data are collected only by the "1" part of the flag. At this time, there is a method of dividing the data by the maximum value and the level. Combining them well enhances the compression effect.

First, the data format is determined, and how to divide the data portion into the data format is examined. Here, this compression format is referred to as data compression. The flag compression method is specified in the format of the data compression method.

(1) Data Format The data format is divided into a control part (header) and a data part as in the data compression format shown in FIG.

(2) Word Configuration of Control Unit As shown in FIG. 30, WORD1 is fixed at 4 bits and has a basic data configuration function. The functions of WORD2 and WORD3 differ depending on this value.

(3) Data part The following three formats are used according to the values indicated by the control unit.

1-bit fixed length (WORD1 = 1) 1-bit data for the number of data represented by WORD3

Fixed 2 bits or more (WORD1 = 2 to 15, WO
RD2 = 0) Data continues with a fixed bit length and ends with data “0”

Variable data length (WORD1 = 2 to 15, WORD2 = 1
7) Data that can be represented by the bit length of WORD1 has an identification code “0” added to make it the bit length of WORD1. The data that cannot be represented has a bit length obtained by adding an identification code “1” and adding WORD1 and WORD2.

At this time, the shorter bit length is WORD1 + 1,
The longer one is WORD1 + WORD2 + 1. Regarding the end of data, set it to “0” at LowLevel. This termination is based on the above WOR
This means that the contents of D1 to WORD3 are changed, and the end of the final data is when WORD1 is "0".

When it is desired to represent "0" by data, it is represented by "0" at HighLevel. Also, HighLevel and Low
The maximum value of Level “111... 1” is −1 data and “111... 10” is −2 data.

As described above, when the bit length of data can be changed, it is more efficient to handle a large amount of data in a certain range. For example, a method of collecting only a range of small data or a method of collecting data of a large range can be considered.

Originally, it is better to perform the constant switching at this changing point. However, if it is performed at all the changing points, the amount of information required for information specification is required, so that it may be worse on the contrary.

[0102] Therefore, according to the bit length change point of data in Figure 31, it takes the change point 4 point data are examined for switching pattern 2 ⁴ street. Switching pattern is small should have, calculation processing is small but even doing more is appropriate to examine up are two ⁴ results are the same.

The case with the least amount of information among all the streets is determined. Focusing on the first point in the obtained case, when the first point is switched, the first point is registered as a conversion, the first is the starting point, the second is the first, the ending point is the fourth, and so on. shift. In this state, the minimum value of the information is obtained again. This process is repeated to determine a change point.

When the first is not the exchange point, the second and subsequent points are shifted one by one and the same processing is repeated. When the fourth point is the final point, the minimum case is obtained, and all the points to be converted in that case are registered as conversion points. Through the above processing, the conversion time at which the data amount is minimized can be obtained.

From the beginning, the obtained conversion point group is used as a data delimiter, and compression information is inserted every time to create compressed data. In FIG. 32, the effect of the method by this division is shown as a fixed-length and variable-length compression effect, as compared with the case without division.

3.3 Flag Compression Method (when WORD1 = 1) Referring to the format configuration of the flag compression method shown in FIG. 33, the flag compression method encodes "0" and "1" data in 1-bit units. Therefore, it is necessary to specify the number of data in advance. The number of data bits is specified in advance.

3.4 Data Creation Algorithm of Data Compression Method In this method, the bit length of a part is changed at an appropriate place so that a series of data can be encoded with the minimum number of bits. The algorithm first calculates the bit length of all data, determines whether it is better to change the bit length at the point where the bit length changes, and sets the change point.

In this case, as shown in FIG. 34, all cases up to four points ahead are calculated, and it is determined whether or not the change should be made at the first point. In this manner, the shift is sequentially determined to determine the change point setting.

(Creation of Optimal Data) Referring to FIG.
The maximum number of bits and the minimum number of bits are determined for each change point obtained as described above, and an optimum constant is set. As a result, optimal data is created. (Method of receiving compression-encoded road traffic information)

Next, with reference to FIG. 36 to FIG. 45, the details of the method for compressing and encoding road traffic information according to the present invention will be described. (Receiving side compressed data decompression method) A method of decompressing compressed data will be described. FIG. 37 lists the decompression items in order when decompressing all traffic jam information. Details of the decompression items are shown in FIG. FIG. 38 reproduces the secondary mesh and the link section. The result is read out from the compression format table shown in FIG. 4 and reproduced.

By the processing shown in FIGS. 40 to 44, all the undecompressed portions shown in FIG. 40 can be reproduced. Explanations are given for each item.

(1) Secondary mesh number, link classification

There are many link numbers in one secondary mesh number. Since the number of link sources is one, generally only one link source is required if data is collected by the information source.

Therefore, only the secondary mesh number needs the number of links. The secondary mesh number itself is not a large number. When reading data, first, the secondary mesh code is represented by 16 bits. The values of the difference (EXOR) are shown after the second. Read the value and EXOR
You just have to take it back.

Since the secondary mesh numbers are bit-arranged on the sending side so that continuity is obtained, the secondary mesh numbers can be reproduced by rearranging them in reverse order.

Next, for each secondary mesh number,
You just need to find out how many links correspond. For the data, the difference between the number of links and the secondary mesh number is encoded by a data compression method. If this is read, the number of data can also be read, so that it is possible to know up to where the secondary mesh number is and from where the link number data.

The table shown in FIG. 39 is created by reading these data. As a result, only the secondary mesh number and the link section are decompressed and reproduced.

(2) Link number This data utilizes the fact that links are arranged in ascending order, adds 1 to the previous link number, takes EXOR, and sets "0"
Has a lot of data. Since “0” and non- “0” data are encoded in the flag format, the data in this flag format is read, and the non- “0” value is read by the data compression method to correspond to the previous non- “0”. Then, the EXOR value of the link number is created. If you take the EXOR of this value and add 1, you can reproduce the link number.

(3) Degree of congestion The method of converting the Huffman code of FIG. 41 into a numerical value is shown. Although the congestion degree is encoded by the Huffman code, the number is not known, so the number of data is indicated first, followed by the Huffman code for the number of data.

(4) Traffic jam extension data First, the presence / absence of extension information is read in the form of a flag. Next, the traffic length data is read. If this data is made to correspond to the link of the flag "1", the traffic jam length can be reproduced. Following the head position, there are further flag data of "0" and non- "0", which are read, and then the data of the head position is read.
This may be applied to a non- "0" link.

(5) Similar to the extension of the link travel time congestion, the flag signal is read first, then the value in the data compression format is read, and the link corresponding to "1" may be read. Further, the data in the flag format is read, and for the flag signal “1”, “0”
Is the data representing the aggregation.

The apparatus for compressing / encoding road traffic information, the apparatus for decompressing / decoding / decoding it, the method for transmitting / compressing / encoding it and the method for receiving / decompressing / decoding it according to the present invention have been described above. become that way.

(Pre-processing means) EXOR EXOR with numerical processing Swap bit positions (rearrange)

(Encoding method) Flag encoding Non- "0" separation flag encoding Variable word length coding (data compression) Run-length coding Huffman coding

In the present invention, tabular data can be compression-encoded. In principle, data should be an integer of -2 or more. Road traffic information includes character data such as place names, which will be discussed separately.

[0125] Definitions can be made beforehand so as to be compatible with all types of table data. However, since these definitions are complicated, it is assumed that they are defined in advance on the transmitting and receiving sides. Depending on the characteristics (characteristics) of the data, high-compression encoding can be performed by using an optimal combination of some of the preprocessing means and encoding methods for each item.

As described above, in the present embodiment, the following evaluation results can be obtained. It can be expected that the compression ratio of road traffic information can be reduced to less than 30% by comparing with the same binary data, and can be reduced to 3% or less when compared with the XML description.

As described above, the present invention is not limited to the above embodiment, but can be implemented in various forms. It goes without saying that the present invention is also applied to a program describing the method of compressing / encoding road traffic information and the method of receiving / decompressing / decoding it according to the present invention, a recording medium storing this program, and a transmission medium transmitting this program. . For example, the program that describes the method of receiving and compressing and encoding road traffic information and the tabular data table of the present invention is transmitted from the transmitting side in FIG.
The receiving means 71 and the tabular information supply means 9 of the receiving-side mobile unit shown in FIG.
5 may be transferred.

[0128]

According to the present invention, a road traffic information compression-encoding transmission apparatus, a decompression decoding reception apparatus thereof, and a compression code thereof capable of expecting a particularly high compression effect in the compression encoding of road traffic information. And a decrypted decoding receiving method.

[Brief description of the drawings]

FIG. 1 is a block diagram of a device for compressing and encoding road traffic information according to an embodiment of the present invention.

FIG. 2 is an example of a table data table of road traffic information in the road traffic information compression-encoding transmission device of FIG. 1 and shows the contents of traffic congestion information (position data and traffic congestion data).

FIG. 3 is a table of an encoding preprocessing unit applied to each item according to the road traffic information compression encoding transmission apparatus of FIG. 2;

FIG. 4 is a diagram showing a compression format table of road traffic information of FIG. 2;

FIG. 5 is a diagram showing a bit position replacing means 4 of the data compression preprocessing means 39 in the apparatus for compressing and encoding road traffic information shown in FIG. 1;
FIG. 5 is a diagram for explaining No. 5;

FIG. 6 is a diagram showing a data format of a link number of road traffic information.

FIG. 7 is a diagram illustrating a compression format of traffic congestion data of road traffic information.

FIG. 8 is a diagram illustrating a congestion length of road traffic information and a compression format of an extension flag.

FIG. 9 is a diagram illustrating a compression format of extended head position data of road traffic information.

FIG. 10 is a diagram illustrating a data compression format of travel time information of road traffic information.

FIG. 11 is a diagram showing a real time / measurement time of road traffic information and an aggregated information data compression format.

FIG. 12 is a table showing a compression rate for each item of a compression effect of the present system and a table format according to the apparatus for compressing and encoding road traffic information of FIG. 1;

FIG. 13 is a table showing the distribution of consecutive numbers of “0” in road traffic information.

FIG. 14 is a table showing distribution of congestion information flags related to road traffic information.

FIG. 15 is a table showing distribution of link travel time extension flags in road traffic information.

FIG. 16 is a diagram showing an exclusive-OR (EXOR) matching circuit and a shift register 3, which are composed of shift registers 1 and 2 and an adder according to the matching determination means 41 of the data compression preprocessing means 39 of FIG. .

FIG. 17 is a table showing frequencies corresponding to 12 bits of road traffic information.

FIG. 18 is a table showing frequencies of road traffic information corresponding to 4 bits.

FIG. 19 is a table showing frequencies corresponding to three bits of road traffic information.

FIG. 20 is a table showing frequencies corresponding to 6 bits.

FIG. 21 is a table showing the number of bits of data and the amount of information.

FIG. 22 is a table showing a distribution of link numbers after processing of an exclusive OR (EXOR) matching circuit;

FIG. 23 is a continuation of the table of FIG. 22;

FIG. 24 is a diagram illustrating a format of a sign of road traffic information.

FIG. 25 is a diagram showing a data format of road traffic information.

FIG. 26 is a table of bit lengths representing “0” of the degree of congestion in road traffic information.

FIG. 27 is a table showing the distribution of the degree of congestion in the form of data and the degree of congestion of road traffic information.

FIG. 28 is a table showing variable length codes of road traffic information.

FIG. 29 is a diagram illustrating a format of a data compression method for road traffic information.

FIG. 30 is a table showing the contents of WORD of road traffic information.

FIG. 31 shows a bit length change point of road traffic information data.

FIG. 32 is a table for comparing effects of a fixed length and a variable length of road traffic information.

FIG. 33 is a diagram illustrating a format of a flag compression method for road traffic information.

FIG. 34 is a flowchart illustrating an algorithm for setting a bit length change point of road traffic information.

FIG. 35 is a flowchart showing an algorithm for determining the maximum bit number and the minimum bit number of road traffic information.

FIG. 36 is a block diagram of an apparatus for decoding and decoding road traffic information according to an embodiment of the present invention.

FIG. 37 is a flowchart showing decompression of all traffic jam data of road traffic information.

FIG. 38 is a flowchart illustrating a read / reproduction process of a secondary mesh number and a link section of road traffic information.

FIG. 39 is a table showing a result of a reproduction process of a secondary mesh number and a link section of road traffic information.

FIG. 40 is a flowchart showing a link number reading and reproducing process of road traffic information.

FIG. 41 is a flowchart showing a process of reproducing the degree of congestion of road traffic information.

FIG. 42 is a flowchart showing a process of decompressing traffic congestion extension data of road traffic information.

FIG. 43 is a flowchart showing link travel time decompression processing of road traffic information.

FIG. 44 is a flowchart illustrating a flag format code decompression process for road traffic information.

FIG. 45 is a flowchart illustrating a data compression format code decompression process for road traffic information.

[Explanation of symbols]

11 Sensor 13 Road traffic information generation means 15 VICS Center 17 Road traffic information input means 21 Compression encoding means 25 Tabular data table creation means 27 Item-specific data feature extraction means 29 Encoding method selection means 31 Flag data encoding method 33 Variable Bit Length Data Coding 35 Run-length coding 37 Huffman coding 39 Data compression preprocessing means 41 Match determination means 43 Non-matching identification means 45 bit position exchange means 47 Data Reorganization Method by Item 50 compression means 51 Digital modulation means 53 Transmission means 71 Moving object receiving means 73 Digital demodulation means 75 Decompression means 77 Encoding method discriminating means 83 Coding method restoration means 85 Flag data encoding method 87 Variable Bit Length Data Coding 89 run-length coding 91 Huffman coding 92 Item-specific data reproduction means 93 Data Reorganization Method by Item 95 Tabular information supply means 97 Tabular data table creation means

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Claims (10)

[Claims] 1. A road traffic information compression-encoding transmission apparatus for transmitting road traffic information in the form of a compression code, wherein the compression-encoding transmission apparatus encodes the road traffic information to generate encoded information. Encoding means for generating, and compression means for compressing the encoded information to generate the compression code, wherein the encoding means receives the road traffic information and converts the road traffic information to A tabular data table creating means for rearranging and organizing to prepare a tabular data table; an item-by-item data feature extracting means for analyzing and extracting data features of the tabular data table by item; And a coding method selecting means for selecting a predetermined coding method having a correlation of the compression effect with respect to the tabular data table and generating the coding information. Compression coded transmission device for communication information. 2. The encoding means, which is arranged before the compression means, comprises:
The apparatus for compressing and encoding road traffic information according to claim 1, further comprising data compression preprocessing means for preprocessing desired data. 3. The predetermined coding system of the coding system selection means is any one of a flag data coding system, a variable bit length data coding system, a run length coding system, and a Huffman coding system. The apparatus for compressing and encoding road traffic information according to claim 1, wherein: 4. The road traffic information according to claim 1, wherein the data characteristic is information including at least one of a number of the data, a distribution bias, and a number of bits forming a bit string. Compression coded transmission device. 5. The data compression pre-processing means receives two of the data features, determines whether or not the corresponding bit strings of the data features match, and indicates a bit string indicating the matching of the corresponding bit strings. A coincidence determining means for generating a coincidence signal; and a non-coincidence identification for generating a non-coincidence bit number signal indicating a non-coincidence bit number among the corresponding bit strings of the data characteristics to identify the data characteristics. Means, bit position interchange means for exchanging the positions of the bits of the bit string representing the data characteristics, and item-by-item data reorganization means for reorganizing the data characteristics by the items. The apparatus for compressing and encoding road traffic information according to claim 2. 6. The coincidence determination means receives the two data features in order, and
A pair of shift registers for shifting the next data feature once to generate a data output signal by shifting the subsequent data features once, and adding the data outputs to each other. 5. The apparatus according to claim 4, further comprising: data addition means for calculating an exclusive OR of the two data features. 7. A decompression decoding receiver for road traffic information for receiving and decompressing decoding of a compression code of road traffic information, wherein the decompression decoding receiver decompresses the compression code, and encodes the compressed code. Decompressing means for generating information, and decoding means for decoding the encoded information into the road traffic information, wherein the decompressing means receives the itemized data obtained by decompressing the compression code, An apparatus for decompressing and decoding road traffic information, comprising: a coding method determining means for determining an optimum coding method for a data feature of the item-specific data. 8. The decoding means receives the coded information, and receives a flag data coding method, a variable bit length data coding method, a run length coding method,
And a predetermined encoding method comprising a Huffman encoding method, an encoding method restoring means for restoring any encoding method as being optimally selected, and the encoding method being selected and the code Item-by-item data reproducing means for reproducing item-by-item data from fragmentation information; item-by-item data reorganizing means for reorganizing the item-by-item data; 8. A decompression decoding reception of road traffic information according to claim 7, further comprising: a tabular data table creating means for reading and creating a tabular data table in which the road traffic information is arranged from another data. apparatus. 9. A method of compressing and encoding road traffic information for transmitting road traffic information in the form of a compression code, wherein the compression encoding and transmitting method encodes the road traffic information and encodes the encoded information. An encoding process for generating the compressed traffic information, and a compression process for generating the compressed code by compressing the encoded information. The encoding process receives the road traffic information and converts the road traffic information to A tabular data table creation step for rearranging and organizing to prepare a tabular data table; an item-by-item data feature extracting step for analyzing and extracting data features of the tabular data table by item; A coding method for selecting a predetermined coding method having a correlation of the compression effect with respect to the tabular data table and generating the coding information. Compression-encoding transmission method of communication information. 10. A decompression decoding reception method for road traffic information for receiving and decompression decoding a compression code of road traffic information, the decompression decoding reception method comprising: decompressing and encoding the compression code. A decompression step for generating information; anda decoding step for decoding the encoded information into the road traffic information.The decompression step receives item-specific data obtained by decompressing the compression code, A method for decompressing and decoding road traffic information, comprising a coding method determining step for determining an optimum coding method for a data feature of the item-specific data.