JP2933541B2 - Duplicate Data Prevention Method for Distributed Receiving System - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for preventing duplicate data in a distributed receiving system, and more particularly, to a plurality of wireless receiving devices in which data sequentially transmitted from a movable wireless transmitting device and to which a sequence number is assigned are distributed. Receive, collect data received by each of the wireless receivers, delete duplicated data based on the sequence number, and reduce the traffic of the data transmission destination. Regarding the prevention method.

[0002]

2. Description of the Related Art A conventional duplicate data prevention system of a distributed receiving system uses a sequence number attached to data transmitted by a radio transmitting apparatus (transmitting station) and distributes the data to a plurality of receiving apparatuses (receiving stations). In a communication control device that aggregates and transfers the data to a higher-level device, duplicate data is determined only in the order of the numbers. That is, it is assumed that the sequence number continues to be simply increased by 1, in order of 1, 2, 3... (However, after reaching the maximum value (for example, 255), the sequence number is reset to the minimum value (for example, 0)). Yes), the sequence number of the received data goes backward except for the case where the sequence number returns from the maximum value to the minimum value in a round compared to the sequence number of the data received before that, or if they are the same, it is judged as duplicate data Was.

[0003]

In the above-described conventional duplicate data prevention system of the distributed receiving system, the radio transmitting apparatuses concentrate around a specific radio receiving apparatus or go out of the service area once and return again. There is a problem in that when the data arrives, it is judged as duplicate data and deleted even though it is normal data. In other words, when a specific wireless receiving device receives data from a large number of wireless transmitting devices intensively, a buffer temporarily accumulated to send received data to the communication control device overflows, and some data is deleted. In the case where a wireless transmission device cannot receive some data because it once goes out of the service area of the wireless reception device (receiving station) and then returns again,
If the sequence number goes round and is smaller than the previously received sequence number, the data is discarded until it exceeds the previous sequence number even though it is new data.

[0004] When data is transmitted from one radio transmitting device at a point where service areas of a plurality of radio receiving devices overlap, if there is a large difference in traffic between these radio receiving devices, the order of data is out of order. There is a problem that normal data is determined to be duplicate data and is deleted. For example, in the case where the sequence number is a repetition of 0 to 100, when switching from 100 to 0, the wireless reception device having the small traffic receives the number 0 or 1
If the data such as No. 100 or No. 99 is delayed from the wireless receiving device having a large traffic after the sequence number such as No. arrives, it is determined that the data is normal because it is larger than No. 0 or No. 1, and then 5 The data of No. 10 and the like are discarded.

[0005] An object of the present invention is to address the case where there is a difference in the traffic of each of a plurality of receiving apparatuses which receive data transmitted with a sequence number from a wireless transmitting apparatus in a distributed manner, which cannot be handled by the conventional method. 1. Use of highly reliable real-time data by preventing normal data discarding due to sequence number deviation and efficiently taking in data when a wireless transmitting device goes in and out of the service area of one wireless receiving device. It is an object of the present invention to provide a duplicated data prevention method for a distributed reception system which enables the following.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a plurality of wireless receiving devices arranged in a distributed manner receive data to which a sequence number is sequentially transmitted from a movable wireless transmitting device. In a duplicate data prevention system of a distributed receiving system for aggregating received data and removing duplicate data based on the sequence number, reception time information is associated with each data received by the plurality of wireless receiving devices, and the wireless transmission is performed. Based on the reception time information, the data received this time for each device is calculated based on the reception time information and the reception time difference is calculated.If the time required for the sequence number to make one round has elapsed, the data received this time is It is determined that the data was transmitted after the previously received data and is not deleted, and the time required for the sequence number to make one cycle has elapsed. In this case, the current sequence number is compared with the previous sequence number by adding a preset condition for reversing the magnitude relation when resetting the sequence number from the maximum value to the minimum value, and the current reception is performed. A communication control device that determines the transmission order of the received data and the previously received data, deletes only the data that can be determined to have been transmitted before the previously received data, and transfers the remaining data that has not been deleted to a higher-level device. Having.

Further, the communication control device: collects and receives data from the plurality of wireless reception devices, determines a data normality, and sends out only normal data; and generates time information. A timer; a sequence number storage circuit for storing a sequence number of previously received data for each wireless transmission device together with time information at the time; and a sequence number and time information from the sequence number storage circuit and the timer. And a data determination circuit for determining the transmission order of the currently received data for each of the wireless transmission devices output from the data reception circuit and the previously received data and deleting duplicate data. be able to.

According to the present invention, a communication control device detects a code error or the like of received data and fetches only error-free data, a sequence number of the data fetched by the data receiving circuit, and a wireless transmission. Device individual ID
, A timer for adding time information at the time when the sequence number storage circuit stores the sequence number and the individual ID, and a sequence number and time between the currently received data and the previously received data. And a data determination circuit that performs determination calculation of the transmission order under certain conditions based on the information, determines whether or not the data is duplicate data, and discards or transfers the data. For example, the sequence number is 0 to 100. For a repetition of
Even if data having a sequence number that appears to be non-overlapping such as 90 or 95 after 10 or 20 is delayed, or if the same data is duplicated from a plurality of wireless receivers, the delay may occur. Data and duplicated data are reliably determined and discarded, and the discarded data is not used as the previous received data to prevent subsequent normal data from being discarded. The traffic of the device can be reduced.

[0009]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the duplicate data prevention system of the distributed receiving system of the present embodiment employs a plurality (only three shown) of radios receiving data from a plurality (only two shown) of wireless transmitting devices (transmitting stations) 8 and 9. A higher-level device 5 such as a central processing unit or the like that performs data processing by aggregating the data received by the receiving devices 1, 2, 3 and the wireless receiving devices 1 to 3 and eliminating duplicate data;
And a communication control device 4 for transferring the data to the remote control system.

Each of the wireless transmission devices 8 and 9 includes a bus, a car,
It is provided as a transmitting station on a moving body such as a truck, and sequentially transmits data having a frame configuration as shown in FIG. 2 while moving or stopping. That is, following the "frame synchronization signal", the "sequence number" indicating the transmission order, the individual "ID number" for device identification, the "information" to be transmitted, and the "CR"
C "is transmitted.

Each of the wireless receiving devices 1 to 3 has a service area as a receiving station while partially overlapping each other.
It receives the data from the wireless transmission device (plurality) in its service area and transmits it to the communication control device 4 while temporarily storing it in a buffer (not shown). The maximum number of data that can be stored in the buffer is, for example, about 50, and when overflow occurs, the oldest data is discarded.

The communication control device 4 includes a data receiving circuit 41 that collectively receives data from the receiving stations (wireless receiving devices 1 to 3), a timer 44 that generates time information (timer data), an ID number, A sequence number storage circuit 42 for storing the sequence number of the previously received data together with the time information;
2 and a data determination circuit 43 that deletes redundant data from the data received by the data receiving circuit 41 based on the information from the timer 44 and sends the data to the host device 5.

Next, the operation of this embodiment will be described.

[0015] The communication control device 4 includes:
The data reception circuit 41 receives data (FIG. 2) from the wireless transmission devices 8 and 9 transmitted from the data transmission circuit 8. The data receiving circuit 41 detects a code error in the received data. If the data is erroneous, the data is discarded. If the data is error-free, the sequence number and the I / O of the transmitting station are selected from the received data.
At the same time as sending the D number to the sequence number storage circuit 42,
All the received data is sent to the data judgment circuit 43. When receiving the sequence number and the ID number from the data receiving circuit 41, the sequence number storage circuit 42 receives time information at the time of receiving the data from the timer circuit 44 and stores the time information together with the sequence number and the ID number. When the sequence number information having the same ID number comes next, the sequence number storage circuit 42 sends the sequence number information having the same ID number received last time to the data judgment circuit 43.
At this time, the reception time difference between the previous reception data and the present reception data based on the time information (timer data) is set to a preset time, for example, the sequence number is set to 1 per second.
And the data buffer on the system is 50
If the sequence number does not accumulate, and if the sequence number does not delay by more than 50, such as discarding old data, the time exceeds 51 seconds, which is the time when the system recognizes that the sequence number has been sufficiently repeated normally. If the data receiving circuit 4
Do not discard the data just received from 1. If this time has not elapsed, the process of determining duplicate data is performed according to the set conditions. The sequence number storage circuit 1
When there is no previous received data in the data judgment circuit 2,
Does not send anything.

The data judging circuit 43 performs an overlapping data judging process based on the received data from the data receiving circuit 41, the sequence number, the ID number, the timer data from the sequence number storage circuit 42, and the timer data from the timer 44. This will be described in detail with reference to the operation flow of FIG. In FIG. 3, S1 to S8 indicate steps of a data determination process.

For example, if the sequence number is a repetition of 0 to 255 (8 bits), first in step S1, the previous data having the same ID number as the data received this time is set based on the timer data. It is checked whether it has passed, and if it has passed, it is determined that the data is not duplicate data, and the process proceeds to step S7. If it has not passed, the process proceeds to step S2 to determine whether or not it is duplicate data. In step S2, it is checked whether the sequence number received this time is a value larger than 0 on the minimum value side of the repetition boundary by a predetermined value, for example, 51 or more. Proceed to step S3. In step S5, the sequence number received last time is 255 on the maximum value side of the repetition boundary.
A value smaller than the predetermined value, for example, 204 (= 255−
51) It is checked whether it is less than 204. If it is 204 or more, the process proceeds to step S3. In step S6, the size of the sequence number received this time is compared with the size of the sequence number received last time.
Then, if it is not larger than the previous time, it is regarded as duplicate data, and the process proceeds to step S8.

In step S3, the magnitudes of the sequence number received this time and the sequence number received last time are compared. If the current time is larger than the previous time, it is considered that the data is not duplicated data, and the process proceeds to step S7. Proceed to. The condition for proceeding to step S4 is that the current sequence number is 51 or more and the previous sequence number is 2
Except when the number is less than 04, the current sequence number is not higher than the previous sequence number.

In step S4, the data which is discarded in the prior art, that is, the data of the sequence number near the minimum value of the repetition boundary received after the previous reception of the data of the sequence number near the maximum value of the repetition boundary is stored. This is a process for rescue. The current sequence number is subtracted from the previous sequence number, and if the operation result is larger than a predetermined value, for example, 51, the current data is regarded as not duplicated data, and the process proceeds to step S7. For example, the current data is regarded as duplicate data, and the process proceeds to step S8.

In step S7, the data received this time is recognized as not overlapping with the data already received, a receiving process is performed, and the data is transferred to the host device 5.

In step S8, the data received this time is recognized as overlapping with the data already received, discarded, and the data is not transferred to the host device 5. When the data is discarded, the data determination circuit 43 notifies the sequence number storage circuit 42 and does not store the sequence number of the data received this time.

[0022]

As described above, according to the present invention, reception time information is associated with each data received by a plurality of radio reception devices, and data received this time for each radio transmission device is based on the reception time information. Calculates the reception time difference from the previously received data, and if the time required for the sequence number to complete one cycle has elapsed, determines that the currently received data is data transmitted after the previously received data and does not delete it If the time required for the sequence number to make a round has not elapsed, a preset condition for reversing the magnitude relation at the time of resetting the sequence number from the maximum value to the minimum value is added, and the current sequence number and the previous By comparing the sequence numbers with the sequence numbers of the above, the transmission order of the currently received data and the previously received data is determined,
Since only data that can be determined to have been transmitted before the previously received data is deleted, if there is a large difference in wireless traffic between the wireless receiving devices, the data may be delayed even if the same data may be delayed significantly. In addition to reliably deleting the duplicated data before performing the processing, the deleted data is not used as the previously received data, thereby preventing subsequent normal data from being deleted. Can be reduced in the traffic of a higher-level device that processes.

Further, even if there is a missing before and after the reset of the sequence number (around the maximum value and the minimum value), it is possible to accurately determine the duplicated data. Is possible,
The number of sequence numbers (digits) can be reduced,
Data size can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a diagram showing an example of a format of data supplied to the communication control device shown in FIG.

FIG. 3 is a diagram showing an operation flow of the data determination circuit shown in FIG. 1;

[Explanation of symbols]

 1, 2, 3 wireless receiving device (receiving station) 4 communication control device 5 host device 8, 9 wireless transmitting device (transmitting station) 41 data receiving circuit 42 sequence number storing circuit 43 data determining circuit 44 timer

Claims (2)

(57) [Claims] 1. A plurality of wireless receivers arranged in a distributed manner receive data sequentially assigned from a movable wireless transmitter and provided with a sequence number, and aggregate the received data of the respective wireless receivers to form the sequence. In a duplicate data prevention method of a distributed reception system that deletes duplicate data based on a number, the reception time information is associated with each data received by the plurality of wireless reception devices, and the data received this time for each of the wireless transmission devices is On the other hand, based on the reception time information, the reception time difference from the previously received data is calculated, and if the time required for the sequence number to make one cycle has elapsed, the currently received data is transmitted after the previously received data. If the time required for the sequence number to make a round has not elapsed, the sequence number is not deleted. By comparing the current sequence number with the previous sequence number by adding a preset condition for the reversal of the magnitude relation when resetting from the maximum value to the minimum value, the data received this time and the data received last time It has a communication control device that determines the transmission order with data, deletes only data that can be determined to have been transmitted before the previously received data, and transfers the remaining data that has not been deleted to a higher-level device. To prevent duplicate data in distributed reception systems. 2. A data receiving circuit, wherein the communication control device collectively receives data from the plurality of wireless receiving devices, determines a normality of a code configuration of the data, and sends out only normal data, and time information. A sequence number storage circuit that stores a sequence number of previously received data for each wireless transmission device together with time information at that time, a sequence number and time from the sequence number storage circuit and the timer A data determination circuit that determines the transmission order of previously received data for data received this time for each wireless transmission device output from the data reception circuit with reference to information and deletes duplicate data. 2. The method for preventing duplicate data in a distributed reception system according to claim 1, wherein