JPH08181633A - Information collection system - Google Patents

Abstract

PURPOSE: To provide an information collection system in which an interrogator simply separates and identifies response signals from all responders in existence within the identification enable range. CONSTITUTION: When a question signal is sent from an interrogator 1, a responder 12 within the identification enable range receives the question signal and sends a response signal in a transmission timing at random. The interrogator 11 applies reception processing to the response signal from the responder 12 for a prescribed period and sends a reception acknowledge signal to the identified responder 12 and sends a question signal again. The responder receiving the reception acknowledge signal reaches a non-response state for a prescribed period and only the responders not identified send a response signal. The interrogator separates and identifies the response signal of all the responders within the specific range through the repetition above.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an information collecting system which uses a wireless information medium as a responder and causes a responder existing within an identifiable range of an interrogator to transmit and collect information.

[0002]

2. Description of the Related Art As shown in FIG. 3, an information collecting system using a conventional wireless information medium (hereinafter referred to as a wireless card) includes an interrogator 11 installed at a specific location,
It is composed of a transponder 12 which is carried or attached to a large number of moving objects. A wireless card capable of contactless communication is used for the transponder 12.

The interrogator 11 generates an interrogation signal by the signal processor 111, modulates the interrogation signal by the transmitter 112, amplifies the power, and sends the interrogation signal from the antenna 113 toward a specific range.
Further, the radio wave from that range is captured by the antenna 113, received by the receiver 114, demodulated and detected, and the received content is identified by the signal processor 111.

The transponder 12 includes the antenna 121 and the transponder 1
When the radio wave from 1 is captured, the power is automatically turned on, the receiver 122 receives the interrogation signal, demodulates and detects the signal, and the signal processor 12
In 3, it is determined whether the inquiry signal is addressed to itself, and if it is addressed to itself, the corresponding information is read from the memory 124, converted into a response signal of a predetermined format, modulated by the transmitter 125, amplified in power and transmitted from the antenna 121.

The interrogator 11 sends out an interrogation signal at regular intervals and receives a response signal from the transponder 12 during that period.
Here, a unique ID code is stored in advance in the memory 124 of each responder 12 as self-identification information, and the interrogator 11 first requests the responder 12 for the ID code,
When the ID code is identified, individual communication is performed.

In the above system, as shown in FIG. 4, when a plurality of transponders 12A to 12D are present within the distinguishable range of the interrogator 11, the transponders 12A to 12D simultaneously ask the questions. Since the interrogator 11 receives the inquiry signal, each of the responders 12A to 12D simultaneously transmits the unique ID code.

In this case, as a result, since the response signals from the plurality of responders 12A to 12D arrive at the receiver 114 of the interrogator 11 at the same time, they interfere with each other and normally receive the signals from any of the responders. Responder 12 that cannot perform signal processing or has the greatest power on the S / N closest to the interrogator
Only the signal from D can be received and the signal identification processing can be performed.

In any case, in the conventional system configuration, the unique ICs of all the transponders existing within the distinguishable range
There was a drawback that the codes could not be separated and identified. As a method for solving the above-mentioned drawbacks, in general, (a) TDM
A: scanning method (time division control method), (b) FD
Three systems, MA: frequency control system and (c) CDMA: code control system are considered.

However, the TDMA system has a drawback that it takes too much time when there are many types of transponders.
The MA method has a drawback that the device configuration is complicated and the scale becomes large when there are many types of responders, and the CDMA method has many types of pseudo-noise codes when there are many types of responders, which makes management difficult. And that the equipment is complicated.

Further, as a method for solving the above-mentioned drawbacks, there is a concrete description in JP-A-6-232781. In this method, the natural frequency is changed for each responder, and the above-mentioned drawbacks can be eliminated. However, when there are many types of responders (for example, 60 million types), the responder side must change the frequency of the oscillator according to the natural frequency, and the interrogator side identifies the corresponding natural frequency. A frequency analyzer must be provided, which is difficult to realize.

Further, as a method for solving the above-mentioned drawbacks, there is a concrete description thereof in Japanese Patent Publication No. 6-71224. This method is to change the amplitude of the interrogation signal of the interrogator over time. However,
This is effective when the moving direction and moving speed of the transponders are known in advance, but it is not useful when a plurality of transponders move in random directions at random speeds.

[0012] The publication also describes a method in which a plurality of antenna beams are provided in different directions and the interrogation signals are transmitted in a time-divisional manner, but many responders also have random directions. However, in the case of moving at a random speed, many antennas are required, and a large amount of time is required for time division control, which is difficult to realize.

[0013]

As described above, in the information collecting system using the conventional wireless information medium for the responder, the unique IDs of all the responders existing within the identifiable range on the interrogator side. There is a drawback that the codes cannot be easily separated and identified.

The present invention has been made to solve the above problems, and provides an information collecting system capable of easily separating and identifying the response signals of all the responders existing within the distinguishable range on the interrogator side. The purpose is to

[0015]

In order to achieve the above object, the present invention is to install an interrogator at a specific location and cause the interrogator to transmit an interrogation signal toward a specific range. In the information collecting system that collects the information from each responder by transmitting the response signal to the responder existing in the interrogator and receiving and identifying the response signal on the interrogator side, the interrogator receives and identifies the response signal. Means for transmitting a reception confirmation signal to the transponder, a period for transmitting the inquiry signal, a period for receiving and identifying the response signal from the transponder, and a processing time divided into a period for transmitting the reception confirmation signal. And a means for causing the responder to receive no response for a certain period when the reception confirmation signal is addressed to itself, and a transmission timing of the response signal each time the inquiry signal is received. It is characterized in further comprising a means for randomizing.

[0016]

In the information collecting system having the above structure, when the interrogator side transmits the interrogation signal, the transponders within the identifiable range receive the interrogation signal and transmit the response signal at random transmission timing. The interrogator side receives and processes the response signal from the transponder for a certain period of time, transmits a reception confirmation signal to the identified transponder, and then transmits the interrogation signal again. The transponder that has received the reception confirmation signal remains in a non-responsive state for a certain period, and only the transponder that is not identified transmits the response signal. By repeating this, the response signals of all the transponders within the specific range can be separately identified.

[0017]

Embodiments of the present invention will be described in detail below with reference to FIGS. FIG. 1 shows the configuration of a data carrier system according to the present invention. However, in FIG. 1, the same parts as those in FIG. 3 are denoted by the same reference numerals, and different parts will be mainly described here.

In FIG. 1, a time controller 115 is provided in the interrogator 11, and a randomizing controller 126 is provided in the responder 12. First, upon receiving the inquiry signal from the interrogator 11, the responder 12 does not immediately transmit the unique ID code as in the conventional case, but waits for a random time width determined by the internal randomization controller 126. The unique ID code is sent after the installation.

Specifically, the signal processor 123 controls the timing of reading the unique ID code from the memory 124 by a control signal from the randomizing controller 126, thereby randomizing the transmission timing of the unique ID code. .

On the other hand, the interrogator 11 does not constantly emit the interrogation signal to the space as in the conventional case, but divides the operating time of the interrogator 11 into at least three units by the time controller 115.

This makes it possible to separate and identify the unique ID codes of all the transponders existing within the identifiable range. Hereinafter, a detailed description will be given with reference to FIG. It should be noted that in FIG. 2, two transponders 12 are provided within the distinguishable range of the interrogator 11.
The case where A and 12B exist is shown.

The time controller 115 in the interrogator 11 is shown in FIG.
As shown in, the operating time of the interrogator 11 is divided into at least three units T1 to T3. T1 is a time period in which the interrogator 11 emits an interrogation signal into space, and T2 is a plurality of responders 12
Responders 12A and 12B which received the unique ID code from A and 12B and processed the signal, T3 was able to receive normally
Is a time zone in which a reception confirmation signal is transmitted. The interrogator 11 always repeats the control cycle in the order of T1, T2, T3.

First, when the interrogator 11 emits an interrogation signal into space, if there is no responder within the identifiable range, there is no movement during the time periods T2 and T3. Here, there are transponders 12A and 12B within the identifiable range (two in FIG. 2, but of course, more may be used). Unique ID after waiting time
Submit the code.

In this case, each waiting time is a random time controlled by the randomizing controller 126 in the responders 12A and 12B, and is different for each responder. Random time that is different each time you receive. In FIG. 2, the symbols Tra and Trb are used.

Next, when the unique ID code from each of the responders 12A and 12B is normally received by the interrogator 11 and subjected to signal processing, the interrogator 11 responds to the responders 12A and 12B with respect to the responder 12A. , 12B with a unique ID code, and a reception confirmation signal is transmitted.

When the responders 12A and 12B respectively receive the reception confirmation signal, the responders 12A and 12B compare the received unique ID code with the self-owned unique ID code. Even if received, this is ignored.

In this sequence, each responder 12
Since the waiting times Tra and Trb of A and 12B are controlled at random, they may coincide with each other with a certain probability. In that case,
The unique ID codes from the transponders 12A and 12B interfere with each other, and the interrogator 11 cannot receive them properly.

Then, the interrogator 11 again emits the interrogation signal into the space. Then, in each responder 12A, 12B,
Since the waiting time is newly set by the randomization controller 126 independently of the state so far, the waiting time Tra,
The Trb shifts with a high probability, and this time the probability of successful communication increases.

As described above, a retry is performed when a communication collision occurs. The waiting time until the retransmission is performed when the retry is executed is controlled by the random number generated by the randomization controller 126 in the responder 12. At this time, if the transponders have completely the same random number, a communication collision will occur again even if a retry is performed, so a countermeasure is required here.

As a random number generation method, Rn + 1 = aRn + b
There is a system based on (mod.T). In this method, R
0, R1, R2, R3, R4, ... Form a random number sequence. Here, b and T are relatively prime. The values a and b are selected so as to satisfy the conditions that the random number sequence has the statistical properties of the initial hope, that the period is as long as possible, and that the generation speed is fast.

The above random number generation method is adopted for each responder, and an initial value Rn is given randomly for each responder. As a result, even if each responder implements a common random number generation algorithm, the initial value is random for each responder, and the number of retries and the history are also random for each responder. Does not always take the same random value.

Therefore, according to the above configuration, a random time difference is provided for the signal transmission of the transponder so that the signal (individual ID code) from the transponder does not collide, so that the response existing within the identifiable range is provided. The unique ID code of the vessel can be separated and identified with a high probability.

If there are a large number of responders and signals from some responders do not collide and can be received, but signals from the remaining responders collide and cannot be received, In response to the inquiry signal of the cycle, the responder that did not collide in the previous communication receives the reception confirmation signal and becomes no response, and only the responder that collides in the previous communication transmits the signal.

Therefore, the number of responders transmitted this time is certainly smaller than the number of responders transmitted last time. By repeating this operation, the unique ID codes of all the transponders existing within the identifiable range can be separated and identified.

As a concrete example, there are 60 million kinds of responders, the identifiable range is 3 m × 3 m, the number of responders that can simultaneously exist in the identifiable range is 6, and the random numbers are uniform from 1 to 10. If a random number is used, the unique ID codes of all the transponders can be separated and identified with an error rate of 10 ⁻⁶ or less after 7 repetitions.

This also means that T1 = 5 ms, T2 = 2
Assuming 0 ms and T3 = 10 ms, the time required to separate and identify the unique ID codes of all responders with an error rate of 10 ^-6 or less is 7 × (T1 + T2 + T3) = 7 × (5 ms + 20
(ms + 10 ms) = 245 ms, which means that separation and identification can be performed reliably in an extremely short time.

As an application example of the system according to the present invention, an interrogator is provided at a tollgate on an expressway, and a transponder is mounted on the vehicle side. When the vehicle enters the tollgate area, the ID is automatically set. An automatic highway toll collection system that reads the code and performs debit processing at the center, or an interrogator installed at the cash register in the supermarket, and a responder attached to the product, with a basket containing the product A product price automatic totaling system is conceivable in which product prices are automatically totaled just by passing through. Of course, the system is not limited to the above. The present invention can also be implemented in various ways without departing from the scope of the invention.

[0038]

As described above, according to the present invention, it is possible to provide an information collecting system capable of easily separating and identifying the response signals of all the responders existing within the distinguishable range on the interrogator side.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an embodiment of an information collecting system according to the present invention.

FIG. 2 is a time chart showing specific communication processing contents between an interrogator and a responder of the above-mentioned embodiment.

FIG. 3 is a block diagram showing a configuration of a conventional information collecting system.

FIG. 4 is a diagram for explaining a problem of the conventional system.

[Explanation of symbols]

11 ... Interrogator, 111 ... Signal processor, 112 ... Transmitter,
113 ... Antenna, 114 ... Receiver, 115 ... Time controller, 12 ... Responder, 121 ... Antenna, 122 ... Receiver, 123 ... Signal processor, 124 ... Memory, 125 ... Transmitter, 126 ... Andamization controller .

Claims (3)

[Claims] 1. An interrogator is installed at a specific location, and the interrogator side is made to transmit an interrogation signal toward a specific range, thereby causing a responder existing within the range to transmit a response signal, and the interrogator side In the information collecting system that collects information from each responder by receiving and identifying the response signal, the interrogator, means for transmitting a reception confirmation signal to the responder that has identified the response signal, A period for transmitting the interrogation signal, a period for receiving and identifying a response signal from the responder, a unit for dividing the processing time into a period for transmitting the reception confirmation signal, and executing the processing in sequence, the responder, When the reception confirmation signal is received, if the signal is addressed to itself, there is provided no response for a certain period, and means for randomizing the transmission timing of the response signal every time the inquiry signal is received. Collection system. 2. The information collecting system according to claim 1, wherein the response signal of the transponder is individual identification information. 3. The transponder comprises a memory for storing a response signal, and when the interrogation signal is received, the response signal is read and transmitted from the memory, and the transmission is performed by randomizing the read timing. The information collecting system according to claim 1, wherein the timing is randomized.