JP2009071525A - Information collecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information collecting device for improving efficiency in transmitting collection data by giving compression processing time for communication time in a state of a poor compression rate. <P>SOLUTION: The information collecting device 2 performs comparison between the non-compressed data size of the collection data to be transmitted during passage through a communication area 7 when termination data is added to the collection data, so as to be wirelessly transmitted to a road side unit 4 without performing compression, and the compressed data size of the collection data to be transmitted during the passage through the communication area 7 when the termination data is added to the collection data, so as to be wirelessly transmitted to the road side unit 4 after performing compression by a predicted compression rate. When the non-compressed data size is equal to or larger than the compressed data size, the collection data to which the termination data is added without performing compression is wirelessly transmitted. When the non-compressed data size is smaller than the compressed data size, the collection data to which the termination data is added is wirelessly transmitted after performing compression. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an information collection device, and more particularly, a collection unit that collects predetermined collection data, a compression unit that compresses the collection data every time the collection data is collected by the collection unit, and a roadside unit An adding means for adding end data to the collected data collected upon entry into a communication area, and a transmitting means for wirelessly transmitting the collected data with the end data added to the roadside device The present invention relates to an information collecting apparatus.

  Business vehicles such as freight transport trucks and taxis are equipped with information collection devices for operation management. The information collection device collects predetermined collection data such as daily business report data generated according to the operation status of the vehicle and records it in a recording medium such as a memory card. Conventionally, delivery of the collected data to the office PC has been performed according to the following procedure. First, the driver operates an end button provided on the information collecting apparatus. In response to this operation, the information collection device adds end data to the end of the collected data. Thereafter, the driver removes the memory card from the information collecting device, brings it into the office, and connects it to the PC.

  However, in this method, since the memory card is inserted / removed each time, the connection portion of the memory card is severely deteriorated, which causes the life of the information collecting apparatus to be shortened. Therefore, for example, a roadside device capable of wireless communication with the information collecting device is provided at the entrance of the office, and the collected data is collected by wireless communication while the vehicle equipped with the information collecting device passes through the communication area of the roadside device. It is considered to be transferred to. However, since the amount of data in the memory card is large, communication time is required, and there is a possibility that the vehicle may leave the communication area of the roadside device before transmitting the collected data to the end. Generally, in order to shorten the communication time, data compression is performed to reduce the amount of communication data to shorten the time (Patent Documents 1 and 2). Data compression can distribute the compression processing time by using a dynamic compression method that performs compression processing every time collected data is collected.

However, in the conventional information collecting apparatus, it is necessary to add “end data” indicating the end of data collection to the end of the collected data before transmitting the collected data to the roadside device. The addition of the end data is automatically performed in response to the roadside unit entering the communication area in order to prevent errors such as forgetting to operate the end button. For this reason, the information collecting apparatus adds the end data after entering the communication area of the roadside device, and further waits for the subsequent compression process to end, and then starts wireless transmission. Therefore, there is a problem that the communication time with the roadside device is shortened by the compression processing time, and the transmission efficiency of the collected data is poor.
JP-A-9-53658 JP 2004-341884 A

  Therefore, the present invention provides an information collection device that improves the transmission efficiency of collected data by paying attention to the above problems and dividing the compression processing time by the communication time in a situation where the compression rate is poor. This is the issue.

  The invention according to claim 1, which has been made to solve the above-mentioned problems, includes a collecting unit that collects predetermined collected data, and a compressing unit that compresses the collected data every time the collected data is collected by the collecting unit. Adding means for adding end data to the collected data collected in response to the roadside unit entering the communication area, and transmitting means for wirelessly transmitting the collected data with the end data added to the roadside unit And a compression rate prediction means for predicting a predicted compression rate when compression is performed after adding the end data to the collected data, and compression is not performed after adding the end data to the collected data. The uncompressed data size of the collected data that can be transmitted while passing through the communication area when wirelessly transmitted to the roadside device, and the collected data The compressed data size of the collected data that can be transmitted while passing through the communication area when wirelessly transmitted to the roadside unit after being compressed with the predicted compression rate after adding the end data, and comparing the uncompressed data Determining means for determining that compression is not necessary if the time data size is equal to or larger than the compression data size, and determining that compression is necessary if the uncompressed data size is smaller than the compression data size; And the transmission means wirelessly transmits to the roadside unit without compressing the collected data to which the end data is added when it is determined by the determination means that compression is not necessary. When it is determined by the determination means that compression is necessary, the collected data to which the end data is added is compressed by the compression means and then applied to the roadside device. That is configured to wirelessly transmit Te lies in the information collection apparatus according to claim.

  The invention according to claim 2 is characterized in that the determination unit is set to perform the determination each time collection data is collected by the collection unit. Exist.

  According to a third aspect of the present invention, when the determination unit is {1− (time required for compression by the compression unit) / (time to pass through the communication area)} is equal to or less than the predicted compression rate, the uncompressed time If it is determined that the data size is equal to or larger than the data size at the time of compression, and {1- (time required for compression by the compression means) / (time required to pass through the communication area)} is greater than the predicted compression rate, 3. The information collecting apparatus according to claim 1, wherein the uncollected data size is set so as to be determined to be smaller than the compressed data size.

  According to a fourth aspect of the present invention, the compression rate prediction means compresses the collected data to which the end data is added by the compression means, using the data size of the collected data before the end data is added as a recording input. A recording means recorded in association with each other as a post-addition compression rate, an acquisition means for acquiring the data size of the collected data before adding the end data as an acquisition input, and the recording input 4. A predicting unit that searches for an input that matches the acquired input and sets the recorded output corresponding to the searched recording input as the predicted compression rate. It exists in the information collection apparatus of 1 item | term.

  According to a fifth aspect of the present invention, the compression rate prediction means is further recorded in association with a pre-addition compression rate of the collected data before adding the end data as a record input, and the acquisition 5. The information collecting apparatus according to claim 4, wherein the means is configured to further acquire, as an acquisition input, a compression rate before addition of the collected data before adding the end data. .

  According to a sixth aspect of the present invention, the predicting means includes a recording data size recorded in the recording means that matches the acquired data size acquired in the acquiring means, and is recorded in the recording means. Of the compression ratio before recording addition corresponding to the recording data size that matches the acquired data size, when there is no compression ratio before compression that is acquired by the acquisition means. Among them, a pre-recording compression ratio whose order of size is before and after the acquisition pre-addition compression ratio is searched, and an average of two recorded outputs corresponding to the searched two pre-recording compression ratios is predicted. The information collecting apparatus according to claim 5, wherein the information collecting apparatus is set to have a compression rate.

  According to a seventh aspect of the present invention, the predicting unit has no record data size recorded in the recording unit that matches the acquired data size acquired by the acquiring unit, and is recorded in the recording unit. When the compression rate before recording addition does not match the compression rate before acquisition acquired by the acquisition unit, the order of the size of the recording data size is before and after the acquisition data size. 7. The recording data size is searched, and an average of two recording outputs corresponding to the two recording data sizes searched is set as the predicted compression rate. Exist in the information gathering device.

  The invention according to claim 8 is the acquisition acquired by the acquisition unit immediately before adding the end data of the collected data in the recording input each time the collected data to which the end data is added by the compression unit is compressed. A count unit that searches for a record input that matches the input, and increases the number of matches corresponding to the record output if the record output corresponding to the searched record input matches the compression ratio compressed by the compression unit; And the predicting means searches for the record input that matches the acquired input among the record inputs, and when there are a plurality of the record outputs corresponding to the searched record input, 8. The information collecting apparatus according to claim 4, wherein the most frequently recorded output is set to be a selected prediction compression rate.

  As described above, according to the first aspect of the present invention, in the situation where the uncompressed data size is equal to or larger than the compressed data size and there is a large amount of collected data to be transmitted, the collected data with the end data is compressed. In the situation where the amount of collected data is larger when the uncompressed data size is smaller than the compressed data size, the collected data with the end data is compressed by the compression means. Later, it can be transmitted wirelessly to the roadside unit. Thereby, in a situation where the compression rate is poor, the compression processing time can be divided into the communication time, and the transmission efficiency of the collected data can be improved.

  According to the second aspect of the present invention, the determination unit performs the determination every time the collected data is collected by the collecting unit. Therefore, the determination is finished before entering the communication area, and transmission of the collected data is further performed. Efficiency can be improved.

  According to the third aspect of the present invention, it is easy to determine whether {1- (time required for compression by the compression means) / (time for passing through the communication area)} is equal to or less than the predicted compression rate or greater than the predicted compression rate. It can be determined whether the uncompressed data size is equal to or larger than the compressed data size or whether the uncompressed data size is smaller than the compressed data size.

  According to the fourth aspect of the present invention, the search input that matches the acquired input is searched, and the record output corresponding to the searched record input is used as the predictive compression rate. The rate can be predicted.

  According to the fifth aspect of the present invention, the recording means records the pre-addition compression rate immediately before adding the end data of the collected data transmitted to the roadside device as a record input, and is recorded. Since the acquisition unit is set to acquire the pre-addition compression rate immediately before adding the end data of the collected data transmitted to the roadside device as an acquisition input, the predicted compression rate can be predicted more accurately. Can do.

  According to the sixth and seventh aspects of the invention, the predicting means searches for two record inputs close to the acquisition input among the record inputs, and predicts an average of the two record outputs corresponding to the two record inputs searched. Output as compression ratio. Thus, the predicted compression rate can be predicted even if there is no recorded input that matches the acquired input.

  According to the invention described in claim 8, when the predicting means searches for a record input that matches the acquired input among the record inputs, and there are a plurality of record outputs corresponding to the searched record input, the number of matches is one. Select the most output. Thereby, even if there are a plurality of recording outputs corresponding to the recording input, the predicted compression rate can be accurately predicted.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing an embodiment of a communication system incorporating an information collection device 2 of the present invention. FIG. 2 is a configuration diagram of the information collecting apparatus 2 shown in FIG. FIG. 3 is a functional block diagram of the CPU 22A in the information collecting apparatus 2 shown in FIG. FIG. 4 is a block diagram showing a data structure in the database 22C3 shown in FIG. FIG. 5 is a block diagram of the roadside device 4 shown in FIG.

  As shown in FIG. 1, the communication system includes an information collection device 2 mounted on a taxi vehicle 1 and a roadside device 4 installed in an office 3 that manages the taxi vehicle 1. . First, the configuration of the information collecting apparatus 2 will be described with reference to FIG. The information collection device 2 includes a vehicle-mounted antenna AT 1, a wireless device 21, a microcomputer (μCOM) 22, and an interface (I / F) 23.

  The in-vehicle antenna AT1 is an antenna mounted on the taxi vehicle 1. The radio device 21 is a device for performing DSRC (Dedicated Short Range Communication) with the roadside device 4 (to be described later) using the in-vehicle antenna AT1 to receive and transmit data. The radio device 21 has a modulation / demodulation circuit that demodulates and outputs the data received by the vehicle-mounted antenna AT1 to the μCOM 22 or modulates transmission data output from the μCOM 22 and outputs the data to the vehicle-mounted antenna AT1.

  The μCOM 22 is used in various processing steps in the central processing unit (CPU) 22A that performs various processes according to the processing program, a ROM 22B that is a read-only memory storing a program for processing performed by the CPU 22A, and the like. RAM 22C which is a readable / writable memory having a work area, a data storage area for storing various data, and the like. The I / F 23 is an interface circuit for the CPU 22 </ b> A in the μCOM 22 to communicate with the taximeter 5.

  Next, a functional configuration of the CPU 22A of the information collecting apparatus 2 described above will be described with reference to FIG. The CPU 22A has a collection function 22A1, a compression function 22A2, an additional function 22A3, a wireless communication function 22A4, a compression rate prediction function 22A5, and a determination function 22A6.

  The collection function 22A1 is a function for collecting collection data corresponding to daily report data such as rent time and fee of the taxi vehicle 1 from the taximeter 5 and storing it in the collection data area 22C1 provided in the RAM 22C. The compression function 22A2 is a function that dynamically compresses the collected data stored in the collected data area 22C1 every time collected data is collected by the collecting function 22A1.

  The dynamic compression is a method of updating a code tree every time collected data is collected and compressing using the code tree at that time. While static coding, which reads all data and creates a code tree, cannot simultaneously compress data while reading data sequentially, dynamic compression creates code trees and compresses data. This is a compression method that can perform processing simultaneously. As such a dynamic compression method, dynamic Huffman coding or adaptive Huffman coding may be considered.

  Compression is to reduce the amount of information (entropy) by utilizing data redundancy and bias. A famous compression method is the Huffman coding method. In this method, the data having the highest appearance frequency is given a short code, and the data having the lowest appearance frequency is given a long code, so that the overall average code length is shortened to perform compression. That is, as defined by compression, a higher compression rate can be obtained if there is a bias in the data to be compressed, and the compression rate is lower if there is not much bias. Furthermore, if there is no bias, no compression effect can be obtained.

  As a simple example, not a Huffman code, but a compression method indicating data continuity will be shown. The collected data recorded in the taximeter 5 is simplified only to the time and fee for business. The month, day, hour and minute of the business time information are recorded as 1-byte data, and the fee is defined as a 2-byte data format. If the charge is 1000 yen at 10:10 on October 10, the collected data will be 10,10,10,10,10,100. In this case, the collected data after compression can be expressed by 4 bytes of 10,5,00,1. Next, if it was 2000 yen at 10:20 on October 10, the collected data would be 10, 10, 10, 20, 20, 00. In this case, the collected data after compression is represented by 6 bytes of 10, 3, 20, 2, 00, 1. As in these two examples, even in the same data series, not only the compression rate greatly changes depending on the content but also the compression may not be possible like the second data.

  The compression function 22A2 also updates the data size recorded in the data size / compression ratio area 22C2 every time the collected data is compressed. The compression function 22A2 updates the pre-addition compression rate recorded in the data size / compression rate area 22C2 every time the collected data is compressed before adding end data to be described later, and adds end data to be described later. When the collected data is compressed, the post-addition compression rate recorded in the data size / compression rate area 22C2 is updated.

  The additional function 22A3 is a function of adding end data to the collected data when it is detected that the wireless communication function 22A4 described later has entered the communication area 7 of the roadside device 4. The wireless communication function 22A4 is a function for wirelessly transmitting the collected data to which the end data is added to the roadside device 4. The compression rate prediction function 22A5 is a function for predicting the predicted compression rate of collected data when compression is performed after adding end data to the collected data.

  Each time the collected data is collected, the determination function 22A6 adds the end data to the collected data and then compresses the collected data that can be transmitted while passing through the communication area 7 when wirelessly transmitted to the roadside device 4 without being compressed. Time data size DS1 and the compressed data size of the collected data that can be transmitted while passing through the communication area 7 when the end data is added to the collected data and then compressed with the predicted compression rate and wirelessly transmitted to the roadside device 4 DS2 is compared and it is determined that compression is not necessary if the uncompressed data size DS1 ≧ compressed data size DS2, and if uncompressed data size DS1 <compressed data size DS2, compression is necessary. It is a function that determines that there is.

By the way, when the time required to pass through the communication area 7 = t, the time required for compression processing by the compression function 22A2 = T, the wireless communication speed = R, and the predicted compression rate = c, the uncompressed data size DS1 is as follows. In the equation (1), the compressed data size DS2 can be expressed by the following equation (2).
DS1 = R × t (1)
DS2 = R × (t−T) / c (2)

Therefore, the determination function 22A6 determines that compression is not necessary if the following expression (3) or (4) is satisfied, and determination that compression is necessary if the following expression (3) or (4) is not satisfied. To do.
R × t ≧ R × (t−T) / c (3)
Modification (3) c ≧ 1-T / t (4)
Hereinafter, a case where determination is performed using Expression (4) will be described.

  The wireless communication function 22A4 needs to wirelessly transmit the collected data with the end data added to the roadside device 4 without compression when it is determined that the determination function 22A6 does not need to compress the compressed data, and the determination function 22A6 compresses the collected data. When it is determined that there is, the collected data to which the end data is added is compressed by the compression function 22A2 and then wirelessly transmitted to the roadside device 4.

  Next, a detailed configuration of the compression rate prediction function 22A5 will be described. The compression rate prediction function 22A5 includes a recording function 22A51, an acquisition function 22A52, and a prediction function 22A53.

  As shown in FIG. 4, the recording function 22A51 records the data size immediately before adding the end data of the collected data transmitted to the roadside device 4 every time the collected data is wirelessly transmitted, as a recording key A (recording input, recording data size). , The compression rate before addition immediately before adding the end data of the collected data to be recorded is the recording key B (recording input, compression rate before recording addition), and the compression rate after addition when the collected data to which the transmitted end data is added is compressed Are associated with each other as a recording key C (recording output, compression ratio after recording), and recorded in, for example, the database 22C3 as recording means provided in the RAM 22C.

  The acquisition function 22A52 acquires the data size stored in the data size / compression ratio area 22C2 every time the collected data is collected, acquisition key A (acquisition input, acquisition data size), and acquires the compression ratio before addition acquisition key B (acquisition This is a function to acquire as input, compression rate before acquisition). The prediction function 22A53 searches the record keys A and B recorded in the database 22C3 for a match with the acquisition keys A and B acquired by the acquisition function 22A52, and corresponds to the searched record keys A and B. This is a function for predicting the recorded recording key C as the predicted compression rate c.

  Next, the configuration of the roadside device 4 will be described with reference to FIG. The roadside unit 4 includes a roadside antenna AT2, a radio unit 41, a μCOM 42, and an I / F 43. The roadside antenna AT2 is an antenna that forms a communication area 7 at the entrance 6 of the office 3, as shown in FIG. The taxi vehicle 1 entering the office 3 always passes through the communication area 7. The wireless device 41 is a device for performing DSRC with the information collecting device 2 using the roadside antenna AT2 to receive and transmit data. The radio device 41 has a modulation / demodulation circuit that demodulates data received by the roadside antenna AT2 and outputs the μCOM42, or modulates transmission data output from the μCOM42 and outputs the modulated data to the roadside antenna AT2.

  The μCOM 42 stores a CPU 42A that performs various types of processing according to a processing program, a ROM 42B that is a read-only memory that stores programs for processing performed by the CPU 42A, a work area that is used in various types of processing in the CPU 42A, and various types of data. RAM 42C which is a readable / writable memory having a data storage area and the like. The I / F 43 is an interface circuit for the CPU 42 </ b> A in the μCOM 42 to communicate with the management device 8 configured from a PC (personal computer) on the office 3 side. The management device 8 outputs the transferred collected data from an output terminal 9 such as a printer.

  The operation of the communication system configured as described above will be described below with reference to the flowcharts of FIGS. FIG. 6 is a flowchart showing a processing procedure of the CPU 22A in the information collecting apparatus 2 shown in FIG. FIG. 7 is a flowchart showing the determination processing procedure of the CPU 22A in the information processing apparatus 2 shown in FIG.

  First, when the ignition of the taxi vehicle 1 is turned on, the CPU 22A starts processing. Thereafter, taxi vehicle 1 leaves office 3 from the exit of office 3 and starts business. The CPU 22A determines that it has not entered the communication area 7 because it cannot receive the radio wave transmitted from the roadside device 4 during business (N in Step S1), and Steps S2 to S5 are repeated.

  Specifically, the CPU 22A functions as a collection unit, and when collected data such as renting time and fee is generated in the tachimeter 5 (Y in Step 2), performs recording processing to record the collected data in the collected data area 22C1 ( Step 3). Thereafter, the CPU 22A functions as a compression unit, compresses the collected data stored in the collected data area 22C1, and sets the data size and the compression rate at that time to the data size recorded in the data size / compression rate area 22C2 before the addition. A compression process for updating the compression rate is performed (step 4).

  Next, the CPU 22A functions as a compression rate predicting unit and a determining unit, and after adding end data to the recorded collected data, can the compressed data be transmitted more efficiently, or can be transmitted more efficiently without compression? After performing a determination process for determining whether or not (step S5), the process returns to step S1. The determination process will be described below with reference to FIG. First, the CPU 22A functions as an acquisition unit, and at this time, acquires the data size recorded in the data size / compression rate area 22C2 as an acquisition key A and the compression rate before addition as an acquisition key B (step S51).

  Next, the CPU 22A searches for the record keys A and B recorded in the database 22C3 that match the acquired keys A and B acquired in step S51 (step S52). When the recording keys A and B that match both of the acquisition keys A and B can be searched (Y in step S53), the CPU 22A functions as a predicting unit, and predicts the recording key C corresponding to the matching recording keys A and B. The compression rate c is predicted (step S54). For example, if the acquisition key A = 100 and the acquisition key B = 20, as shown in FIG. 4, the recording key C = 25 corresponding to the recording key A = 100 and the recording key B = 20 is predicted as the predicted compression rate c. Is done.

  When the recording keys A and B that match both the acquisition keys A and B cannot be searched (N in step S53), the CPU 22A searches for the recording key A that matches the acquisition key A (step S55). Next, the CPU 22A can search for the recording key A that matches the acquisition key A, that is, there is a recording key A that matches the acquisition key A, and the recording key B matches the acquisition key B. If there is nothing (Y in step S56), the recording key B corresponding to the recording key A that matches the acquisition key A is searched for the recording key B whose size order is before and after the acquisition key B ( Step S57). Next, the CPU 22A functions as a prediction unit, and predicts the average of the two recording keys C corresponding to the two recording keys B searched in step S57 as the predicted compression rate c (step S58). For example, if the acquisition key A = 300 and the acquisition key B = 40, as shown in FIG. 4, the recording key C = 40 corresponding to the recording key A = 300 and the recording key B = 50, and the recording key A = 300. The average 35 of the recording key C = 30 corresponding to the recording key B = 30 is predicted as the predicted compression rate c.

  On the other hand, when the recording key A that matches the acquisition key A cannot be searched and the recording key B that matches the acquisition key B cannot be searched (N in step S56), the CPU 22A determines the size of the recording key A. The recording key A is searched in order of the order of the acquisition key A (step S59). Next, the CPU 22A predicts the average of the recording keys C corresponding to the two recording keys A searched in step S59 as the predicted compression rate c (step S60). For example, if the acquisition key A = 150 and the acquisition key B = 50, as shown in FIG. 4, the recording key C = 25 corresponding to the recording key A = 100 and the recording key C corresponding to the recording key A = 200. The average 50 of = 95 is predicted as the predicted compression rate c.

  Next, the CPU 22A determines whether or not the equation (4) is satisfied using the predicted compression rate c obtained in steps S54, S58, and S60 (step S61). If the expression (4) is satisfied (Y in step S61), the CPU 22A determines that the compression is not necessary, turns off the compression flag (step S62), and then returns to step S1. On the other hand, if Formula (4) is not satisfied (N in Step S61), the CPU 22A determines that compression is necessary, turns on the compression flag (Step S63), and then returns to Step S1. Thereafter, when the taxi vehicle 1 finishes business and enters the entrance 6 in the office 3, the information collecting device 2 receives radio waves from the roadside device 4. In response to this, the CPU 22A determines that it has entered the communication area 7 (Y in step S1), and determines whether or not it is necessary to perform compression communication (step S6).

  If the compression flag is on, the CPU 22A determines that compression communication is necessary (Y in step S6), serves as an adding means, and adds end data to the end of the collected data (step S7). Thereafter, the CPU 22A compresses the collected data to which the end data is added and performs a compression process for updating the post-addition compression rate in the data size / compression rate area 22C2 to the compression rate at that time (step S8). After functioning as a transmission means and controlling the wireless device 21 to wirelessly transmit the collected data (step 9), the process proceeds to step S13.

  On the other hand, if the compression flag is off, the CPU 22A determines that it is not necessary to perform compression communication, and acts as an adding unit, and adds end data to the end of the collected data (step S10). Thereafter, the CPU 22A functions as a transmission unit, controls the wireless device 21 without performing compression processing, and wirelessly communicates collected data (step S11). Then, the CPU 22A compresses the collected data to which the end data is added after the wireless transmission of the collected data is completed, and updates the post-addition compression rate in the data size / compression rate area 22C2 to the compression rate at that time (Step S12), the process proceeds to Step S13.

  In step S13, the CPU 22A records the data size recorded in the data size / compression area 22C2 as the recording key A, the pre-addition compression ratio as the recording key B, and the post-addition compression ratio as the recording key C and records them in the database 22C3. After performing the recording process, the process ends.

  According to the information collection device 2 described above, in the situation where the uncompressed data size DS1 ≧ compressed data size DS2 and the amount of collected data to be transmitted is larger when not compressed, the collected data with the end data added is not compressed. 4 can be wirelessly transmitted, and in the situation where the uncompressed data size DS1 <compressed data size DS2 and the amount of collected data to be transmitted is larger when compressed, the collected data with the end data added is compressed to the roadside device 4 Wireless transmission is possible. Thereby, in a situation where the compression rate is poor, the compression processing time can be divided into the communication time, and the transmission efficiency of the collected data can be improved.

  Further, according to the information collecting apparatus 2 described above, each time collected data is collected, it is determined whether it is better to compress or not, so the determination is finished before entering the communication area 7. Thus, the transmission efficiency of collected data can be further improved.

  Further, according to the information collecting apparatus 2 described above, the uncompressed data size DS1 can be easily converted into the compressed data size depending on whether (1-T / t) is equal to or less than the predicted compression rate c or larger than the predicted compression rate c. It can be determined whether the data size is DS2 or more or whether the uncompressed data size DS1 is smaller than the compressed data size DS2.

  In addition, according to the information collecting apparatus 2 described above, a search is made for a record key A, B that matches the acquisition key A, B, and a record key C corresponding to the searched record key A, B is selected as the predicted compression rate c. Thus, the predicted compression rate can be predicted easily and accurately.

  Further, according to the information collecting device 2 described above, the compression rate before addition immediately before adding the end data of the collected data transmitted to the roadside device 4 is further recorded in association with the recording key B, and Since the pre-addition compression ratio immediately before adding the end data of the collected data is set to be acquired as the acquisition key B, the predicted compression ratio c can be predicted more accurately.

  Further, according to the information collecting apparatus 2 described above, the two recording keys A and B close to the acquisition keys A and B are searched from the recording keys A and B recorded in the database 22C3, and the two recorded records are searched. The average of the two outputs corresponding to the keys A and B is output as the predicted compression rate. As a result, the predicted compression rate c can be predicted even if there is no record key A, B recorded in the database 22C3 that does not match the acquired keys A, B.

  In the information collecting apparatus 2 described above, for example, as shown in FIG. 8, a plurality of recording keys C = 25 and 30 corresponding to the same recording key A = 100 and recording key B = 20 are recorded in the database 22C3. There is a case. In this case, for example, the acquisition keys A and B acquired in step S51 immediately before the end data is added every time the collected data to which the end data is added in steps S8 and S12 is compressed. The matching recording keys A and B are searched, and if the recording key C corresponding to the searched recording keys A and B matches the compression rate by the compression processing performed in steps S8 and S12, the corresponding recording key C is supported. The CPU 22A is provided with a count function for increasing the number of matching times.

  When the CPU 22A searches for the recording keys A and B that coincide with the acquisition keys A and B among the recording keys A and B, the number of matches is found when there are a plurality of recording keys C corresponding to the searched recording keys A and B. Is set so that the recording key C having the largest number is selected. Thereby, even if there are a plurality of recording keys C corresponding to the recording keys A and B, the predicted compression rate c can be accurately predicted.

  Further, according to the information collecting apparatus 2 described above, the data size and the pre-addition compression rate are used as the recording input, but the present invention is not limited to this. For example, only the data size may be used as the recording input.

  Further, according to the information collecting apparatus 2 described above, the predicted compression rate c is predicted using the recording keys A, B, and C that are recorded every time the collected data is transmitted, but the present invention is limited to this. is not. As the recording keys A, B, and C, it is conceivable to predict the predicted compression rate c using those recorded in the database 22C3 in advance.

  Further, the above-described embodiments are merely representative forms of the present invention, and the present invention is not limited to the embodiments. That is, various modifications can be made without departing from the scope of the present invention.

It is a block diagram which shows one Embodiment of the communication system incorporating the information collection apparatus of this invention. It is a block diagram of the information collection device shown in FIG. FIG. 3 is a functional block diagram of a CPU in the information collecting apparatus shown in FIG. 2. It is a figure which shows the data structure in the database shown in FIG. It is a block diagram of the roadside device shown in FIG. It is a flowchart which shows the process sequence of CPU22A in the information collection apparatus 2 shown in FIG. It is a flowchart which shows the determination processing procedure of CPU22A in the information processing apparatus 2 shown in FIG. It is a figure which shows the data structure of the database shown in FIG. 3 in other embodiment.

Explanation of symbols

2 Information collection device 4 Roadside device 22A CPU (collection means, compression means, addition means, transmission means, compression rate prediction means, determination means, acquisition means, prediction means)
22C3 database (recording means)

Claims (8)

Collecting means for collecting predetermined collection data, compression means for compressing the collected data every time the collected data is collected by the collecting means, and the collected information according to the approach to the communication area of the roadside device In an information collecting apparatus comprising: adding means for adding end data to collected data; and transmitting means for wirelessly transmitting the collected data with the end data added to the roadside unit,
A compression rate prediction means for predicting a predicted compression rate when compressed after adding the end data to the collected data;
Uncompressed data size of the collected data that can be transmitted while passing through the communication area when wirelessly transmitted to the roadside device without compression after adding the end data to the collected data, and the collected data Comparing the compressed data size of the collected data that can be transmitted while passing through the communication area when compressed by the predicted compression rate after being added with end data and wirelessly transmitted to the roadside device, the uncompressed Determining means for determining that compression is not necessary if the time data size is equal to or larger than the compression data size, and determining that compression is necessary if the uncompressed data size is smaller than the compression data size; With, and
When the transmission means determines that it is not necessary to compress by the determination means, the collected data to which the end data is added is wirelessly transmitted to the roadside device without being compressed, and is compressed by the determination means. An information collecting apparatus configured to wirelessly transmit to the roadside unit after the collected data to which the end data is added is compressed by the compression unit when it is determined that it is necessary.   The information collecting apparatus according to claim 1, wherein the determination unit is set to perform the determination each time collection data is collected by the collection unit.   If the determination unit determines that {1- (time taken for compression by the compression unit) / (time to pass through the communication area)} is equal to or less than the predicted compression rate, the uncompressed data size is the compressed data size. If it is determined that the above is satisfied and {1- (time required for compression by the compression means) / (time required to pass through the communication area)} is greater than the predicted compression rate, the uncompressed data size is the compression The information collecting apparatus according to claim 1, wherein the information collecting apparatus is set so as to be determined to be smaller than the hourly data size.   The compression rate prediction means records the post-addition compression rate when the collected data added with the end data is compressed by the compression means with the data size of the collected data before adding the end data as a recording input. As output, recording means recorded in association with each other, acquisition means for acquiring the data size of the collected data before adding the end data as an acquisition input, and the recording input that matches the acquisition input 4. The information collection according to claim 1, further comprising: a predicting unit that searches for a recorded output corresponding to the searched recording input and sets the predicted compression rate as the predicted compression rate. apparatus. The compression rate prediction means is recorded in association with the pre-addition compression rate of the collected data before adding the end data as a record input, and
5. The information collecting apparatus according to claim 4, wherein the acquisition unit is set to further acquire, as an acquisition input, a compression rate before addition of the collected data before adding the end data. .   The prediction means has a recording data size recorded in the recording means that matches the acquired data size acquired in the acquisition means, and of the compression ratio before recording recorded in the recording means If there is no match with the pre-acquisition compression ratio acquired by the acquisition means, the order of the sizes of the pre-recording compression ratios corresponding to the recording data size that matches the acquired data size is The compression ratio before recording before and after the compression ratio before acquisition is searched, and the average of the two recording outputs corresponding to the searched two compression ratio before recording is set as the predicted compression ratio. The information collection device according to claim 5, wherein   The prediction means has no recording data size recorded in the recording means that matches the acquired data size acquired in the acquisition means, and of the compression ratio before recording recorded in the recording means When there is no match with the compression ratio before acquisition acquired in the acquisition unit, the recording data size is searched for the recording data size before and after the acquisition data size, the order of the size of the recording data size, 7. The information collecting apparatus according to claim 5, wherein an average of two recorded outputs corresponding to the two recorded data sizes searched is set as the predicted compression rate. Each time the collected data to which the end data is added by the compression means is compressed, the record input that matches the acquisition input acquired by the acquisition means immediately before adding the end data of the collected data is searched for among the record inputs. And a counting means for increasing the number of matches corresponding to the recording output if the recording output corresponding to the searched recording input matches the compression ratio compressed by the compression means, and
When the prediction means searches for the record input that matches the acquired input among the record inputs, and there are a plurality of record outputs corresponding to the searched record input, the record with the largest number of matches The information collecting apparatus according to claim 4, wherein the output is set to be a selected predictive compression rate.

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