JP2002124908A - Group communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a group communication system wherein a system does not stop when a trouble is generated in a parent apparatus. SOLUTION: PHS terminal equipments 1a, 1b, etc., send data of gas meters 2a, 2b, etc., to a switching office 4 via repeaters 3a, 3b, etc., The switching office 4 sends the data to a data collecting center 11 via an ISDN circuit 9. The part between the terminal equipment 1 and the repeater 3 is a wireless private network, and the part between the repeater 3 and the switching office 4 is a wireless public network. The switching office 4 is a base station of a PHS system. That is, the repeater 3 is connected with the public network and the number of the repeaters is much smaller than that of the terminal equipments, so that communication charge is reduced. One terminal equipment 1 can be connected with two or more repeaters 3, so that data communication is not obstructed when one repeater goes out of order.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a group communication system suitable for use in collecting data at a remote place, such as gas meter and meter reading of an electric meter.

[0002]

2. Description of the Related Art In recent years, a system using a PHS (Personal Handyphone System) terminal has been developed as a system for collecting data at a remote place. By the way, PHS
The conditions to be provided differ greatly when the terminal is used for data communication such as a monitoring system and when a terminal is used for ordinary telephone calls. Taking the example of the PHS meter reading terminal, the difference is as follows.

(1) The PHS is used as a fixed installation type communication means not because of its mobility but because the wiring work of a communication cable is omitted. (2) The monitoring function is automated and becomes unmanned. This is a system that collects the monitoring results of remote objects at a central location. The function of monitoring objects is often automated and unmanned. (3) Overwhelmingly low communication volume Meter reading for gas, water, electricity, etc. is in principle once a month. Emergency communication involving security has a low probability of occurrence, and the communication volume that increases even at the maximum is 5% or less. (4) A large number of distributed terminals It is necessary to install a large number of monitoring terminals according to the decentralized monitoring points, such as meter reading of gas, water and electricity, monitoring of the atmosphere and rivers, etc. (5) Grouping of arrangements A typical example is a meter reading terminal installed in an apartment house.

[0004] In view of these differences, it is irrational to charge the same mechanism that a human uses for ordinary telephone calls, resulting in delaying the application of the PHS to data communication such as a monitoring system. Assuming data collection by the command response method of the center call, it is easy to manage the traffic to a certain amount or less. In an emergency communication, a terminal call is made, but the probability is extremely small. According to statistics of a certain system, it is 0.01 to 0.03 cases / terminal / month, and even in an apartment house where 100 households live, an emergency terminal call is 1 to 3 cases / month. Considering the above points, PH
Simply installing the S terminal at the data collection point and using it is wasteful and inefficient. Therefore, a group communication system has been considered in which one master unit is prepared corresponding to a plurality of PHS terminals and the master unit and the data collection center are connected by a wireless public network.

[0005]

SUMMARY OF THE INVENTION However, only 1
The following problems occur only by installing one master unit. (1) If a trouble occurs in the master unit, all slave units (PHS
Terminal) becomes unusable and the system stops. (2) In order to recognize the master unit, the unique eye number (identification number) of the master unit is registered in the slave unit. However, when the master unit breaks down and is replaced, the unique eye number stored in the slave unit is registered. Needs to be replaced with the unique eye code of the new master unit. In this rewriting, all the slave units must be removed from the installation location, transported to the factory, and rewritten, which requires a huge amount of work. (3) If the slave unit breaks down, it is necessary to replace it with a spare slave unit.In this case, it is necessary to order a spare unit with the unique eye code of the master unit at the factory, which takes time and time .

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a group communication system in which the system does not stop even when a trouble occurs in the master unit. . Another object of the present invention is to provide a group communication system capable of easily rewriting a unique number of a parent device in a child device when the parent device fails. Still another object of the present invention is to provide a group communication system capable of easily writing a unique number of a master unit to a replacement slave unit when the slave unit breaks down.

[0007]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the invention according to claim 1 has the following features.
A plurality of terminal devices, a plurality of relay devices connected to the plurality of terminal devices via a wireless private network, and a relay station connected to the plurality of relay devices and a wireless public network, The terminal device is a group communication system having communication means for communicating with at least two of the plurality of relay devices.

[0008] The invention described in claim 2 is the first invention.
3. The group communication system according to item 1, further comprising a maintenance center that is connected to the relay station via a communication line and manages the plurality of relay devices and the plurality of terminal devices. According to a third aspect of the present invention, in the group communication system according to the first or second aspect, the terminal device includes a storage unit in which at least two types of unique numbers of the relay device are registered; When communicating from the device, the communication partner determines whether or not the relay device has a unique number registered in the storage unit, and, if the relay device has the unique number, has a determination unit that determines whether reception is possible. It is characterized by the following.

[0009] The invention described in claim 4 is the invention according to claim 3.
Wherein the terminal device compares the electric field strength of radio waves emitted from the relay device and emits the highest intensity radio wave among the relay devices registered in the storage unit. It has a comparison / specifying means for specifying the relay device, and performs data transmission to the relay device corresponding to the unique number specified by the comparison / specification device.

[0010] The invention described in claim 5 is the first invention.
The group communication system according to any one of claims 1 to 4, wherein the relay device has a unique number transmitting unit that transmits its own unique number in response to a request from the terminal device, wherein the terminal device A unique number transmission request transmitting means for transmitting a unique number transmission request to the relay device, a unique number transmitted from the relay device in response to the unique number transmission request, and first-in / first-out in the storage means Registering means for registering in a system. According to a sixth aspect of the present invention, in the group communication system according to the second aspect, the maintenance center assigns a unique number of the relay device via a public network in response to a request from the terminal device. It has a unique number transmitting means for transmitting to the terminal device, and the terminal device has a registration means for registering the unique number transmitted from the maintenance center in the storage means.

The invention described in claim 7 is the same as the claim 2
Alternatively, in the group communication system according to claim 6, when the relay device registered in the storage unit fails, the terminal device uses a unique number notified from the maintenance center via another relay device. The apparatus further comprises a unique number updating means for rewriting the unique number of the failed relay device in the storage means. The invention described in claim 8 is the invention according to claim 2 or 6 or 7.
In the group communication system according to the above, the terminal device stores an identification number of the maintenance center in the storage unit, and includes an identification number included in a reception process from the maintenance center and an identification number in the storage unit. And receiving data from the maintenance center only when the data match.

The invention according to claim 9 is the invention according to claim 2.
Alternatively, in the group communication system according to claim 6, the maintenance center and the terminal device are respectively an encryption unit for encrypting transmission data and a decryption for decrypting encrypted reception data. Means for performing mutual communication using encrypted data.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the group communication system according to the embodiment, in which a broken line indicates a wireless line and a solid line indicates a wired line. In the figure, reference numerals 1a, 1b,.
Is a PHS terminal device. These terminal devices 1a, 1
are attached to, for example, gas meters 2a, 2b,... installed in an apartment house, and have a CPU (central processing unit) and a wireless communication device under program control, and have a PIAFS ( PHS Internet Acces
s Fortum Standard). It has an interface for recording data from the meters 2a, 2b,.... In the internal memory, relay devices 3a, 3b,.
The unique numbers (identification numbers) of the two relay devices are registered in advance. For example, in the case of the terminal device 1a, the unique numbers of the relay devices 3a and 3b are registered in advance. Further, a program for realizing various special functions described later is stored in an internal ROM (read only memory).

The relay devices 3a, 3b,...
a, 1b,... and the terminal devices 1a, 1b,.
.. And the relay station 4 are relayed. These relay devices 3a, 3b,... And terminal devices 1a, 1
b, ... is a wireless private network (or Bluetooth) 6
And the relay station 4 is connected by a wireless public network 7. The relay station 4 is a base station in the PHS communication system, and is connected to the ISDN line 9. The data collection center 11 includes the meters 2a, 2b,.
, A computer for collecting the data, and the maintenance center 12 are terminal devices 1a, 1b,..., Relay devices 3a, 3
b,... are computers for maintenance.

Next, the operation of the group communication system having the above configuration will be described. First, during normal times, the data collection center 11 operates the meter 2a once a month, for example.
2b,... Are collected. That is, the data collection center 11 first outputs a packet instructing data collection of the terminal device 1a to the relay device 3a via the relay station 4. The relay device 3a adds its own unique number to the packet and transmits the packet to the terminal devices 1a, 1b,. The terminal device 1a receives the packet from the relay device 3a, first reads a unique number included in the packet as shown in FIG. 2 (step Sa1), and the unique number is registered in an internal memory in advance. It is determined whether or not the numbers match (step Sa2). If they match, the packet is received. If they do not match, no packet is received.

When receiving the packet, the terminal device 1a transmits the data recorded from the meter 2a to the relay device 3a. The relay device 3a transmits this data to the data collection center 11 via the relay station 4. Data collection center 1
1 writes the received data into an internal storage device. Next, the data collection center 11 collects data of the meter 2b in the same manner, and thereafter, collects data of all the meters 2a, 2b,... By repeating the same operation.

Next, the repeaters 3a, 3b,... Sequentially transmit a signal for measuring the electric field strength including their own unique number from the repeater 3a at regular intervals (for example, 100 msec). The terminal devices 1a, 1b,...
a, 3b,..., and when the signal is from the relay device 3 having the unique number stored in the memory, the electric field intensity of the signal is measured. Measure and write to internal memory. For example, as shown in FIG. 3, the terminal device 1a first measures the electric field intensity of the signal from the relay device 3a and writes it to the memory (step Sb1), and then measures the electric field intensity of the signal from the relay device 3b. And writes it in the memory (step Sb2). Next, the electric field strength of the signal from the relay device 3a and the
b is compared with the electric field strength of the signal from step b (step Sb
3) The electric field strength of the signal from the relay device 3a is
b, if it is greater than the electric field strength of the signal from
Is determined as the highest electric field strength, and when data is transmitted from the terminal device 1a thereafter, the data is transmitted to the relay device 3a. Thus, each terminal device 1 is connected to the relay device 3a,
Each time a signal for measuring the electric field strength is transmitted from 3b,..., The relay apparatus 3 having the current highest electric field strength is detected and stored.

Next, a case where the terminal device 1a breaks down will be described. Note that the failure of the terminal device 1a is detected in the data collection center 11 when, for example, correct data is not transmitted from the terminal device 1a. When the terminal device 1a breaks down, the attendant first operates the spare terminal device 1m (FIG. 1).
Prepare Next, the relay device 3a to which the backup terminal device 1m is to be subordinate is manually set to the registration mode. Next, when a switch provided on the panel of the standby terminal 1m is operated, a request for sending a unique number is transmitted from the standby terminal 1m to the relay device 3a (step Sc1 in FIG. 4).
The relay device 3a receives this transmission request and transmits its own unique number to the backup terminal device 1m. When receiving the unique number (step Sc2), the spare terminal device 1m writes the unique number into the internal memory (step Sc3). Next, the attendant sets the relay device 3b to which the backup terminal device 1m is to be subordinated in the registration mode. Next, when the switch of the standby terminal device 1m is operated, a request for transmitting a unique number is transmitted from the standby terminal device 1m to the relay device 3b, and the unique number is transmitted from the relay device 3b. The spare terminal device 1m writes this unique number into an internal memory. Next, the spare terminal device 1m in which the registration of the relay device unique number has been completed is set in the meter 2a instead of the terminal device 1a. Writing to the memory is performed by a FIFO (first in / first out) method.

Next, another method of registering the unique number of the above-mentioned spare terminal device 1m will be described. The attendant first switches the standby terminal device 1m to the public line mode (step Sd1 in FIG. 5) and sends a unique number transmission request. This unique number transmission request is received by the relay station 4 and transmitted from the relay station 4 to the maintenance center 12. The maintenance center 12 receives the transmission request and transmits the unique numbers of the relay devices 3a and 3b to the backup terminal device 1m via the relay station 4. The spare terminal device 1m receives this unique number (step Sd2),
Writing to the internal memory (step Sd3).

Next, a case where the relay device 3a breaks down will be described. When the relay device 3a fails, the terminal devices 1a and 1b detect the failure, and thereafter perform communication via the relay device 3b and notify the maintenance center 12 of the failure of the relay device 3a via the relay device 3b. Maintenance Center 1
2 receives this notification and transmits the unique number of the backup relay device 3m together with its own identification number to the terminal devices 1a and 1b via the relay device 3b. The terminal devices 1a and 1b receive the unique number of the relay device 3m and the identification number of the maintenance center (step Se1 in FIG. 6), and first, the identification number of the maintenance center 12 registered in advance in the memory and the received identification number. It is determined whether the numbers match (step Se)
2). If the result of this determination is "NO", the receiving process is stopped (step Se3). On the other hand, if the determination is "YES", the unique number of the relay device 1a in the memory is rewritten to the unique number of the relay device 1m (step S).
e4). Thus, the terminal devices 1a and 1b thereafter communicate with the data collection center 11 and the maintenance center 12 via the relay device 3b or 3m.

In some cases, the failure of the relay device 3a may be detected in the data collection center 11 because there is no data transmission from the relay device 3a. In this case, the data collection center 11 notifies the maintenance center 12 of the fact. In the above system, the terminal device 1a,
1b,..., Data collection center 11, maintenance center 12
Are encrypted, and the terminal devices 1a, 2a,..., The data collection center 11, and the maintenance center 12 are provided with encryption means and decryption means, respectively.

[0022]

As described above, according to the first aspect of the present invention, a plurality of terminal devices and a plurality of relay devices (master units) connected to the plurality of terminal devices via the wireless private network.
And a plurality of relay devices and a relay station connected via a wireless public network, and the terminal device has communication means for communicating with at least two of the plurality of relay devices. The advantage that the system is not stopped even when the error occurs is obtained. According to the fourth aspect of the present invention, the relay device emitting the highest intensity radio wave among the relay devices registered in the storage unit by comparing the electric field intensity of the radio wave emitted from the relay device is determined. It has a comparing and specifying means for specifying, and since data is transmitted to the relay device corresponding to the unique number specified by the comparing and specifying means, it is possible to communicate with a relay device having a good radio wave propagation state. Becomes

According to the fifth and sixth aspects of the present invention, it is possible to easily register a unique number of a relay device in a spare terminal device on site when a terminal device breaks down. Can be According to the seventh aspect of the present invention, when the relay device breaks down, it is possible to easily register the unique number of the spare relay device locally on the terminal device.

[Brief description of the drawings]

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

FIG. 2 is a flowchart for explaining an operation of the terminal device in the embodiment.

FIG. 3 is a flowchart for explaining the operation of the terminal device in the embodiment.

FIG. 4 is a flowchart for explaining the operation of the standby terminal device in the embodiment.

FIG. 5 is a flowchart for explaining the operation of the standby terminal device in the embodiment.

FIG. 6 is a flowchart for explaining the operation of the terminal device in the embodiment.

[Explanation of symbols]

 1a, 1b ...: PHS terminal device 2a, 2b ...: gas meter 3a, 3b ...: relay device 4: relay station 6: wireless private network (or Bluetooth) 7: wireless public network 9: ISDN line 11 ： Data collection center 12 ： Maintenance center

Continuing on the front page (72) Inventor Norio Tanuma 4-10-10 Shiba, Minato-ku, Tokyo Inside NEC Information Technology Corporation (72) Inventor Isao Murakami 4- 10-10 Shiba, Minato-ku, Tokyo Japan Electric Information Technology Co., Ltd. (72) Inventor Fumio Matsumura 4-10, Shiba, Minato-ku, Tokyo NEC Information Technology Co., Ltd. F-term (reference) 5K067 AA33 BB27 DD17 DD44 EE02 EE06 EE10 EE16 HH11 HH22 HH23 5K101 KK12 LL12 PP03 VV05

Claims (9)

[Claims] 1. A plurality of terminal devices, a plurality of relay devices connected to the plurality of terminal devices via a wireless private network, and a relay station connected to the plurality of relay devices via a wireless public network. The group communication system, comprising: a communication unit that communicates with at least two of the plurality of relay devices. 2. The group communication system according to claim 1, further comprising a maintenance center connected to said relay station via a communication line, said maintenance center managing said plurality of relay devices and said plurality of terminal devices. . 3. The terminal device, comprising: a storage unit in which at least two types of unique numbers of the relay device are registered; and a relay device in which a communication partner has a unique number registered in the storage unit when communicating from the relay device. 3. The group communication system according to claim 1, further comprising a determination unit configured to determine whether the relay device has the unique number, and determine whether reception is possible when the relay device has the unique number. 4. 4. The terminal device compares the electric field strength of a radio wave emitted from the relay device, and determines a relay device emitting the highest intensity radio wave among the relay devices registered in the storage unit. 4. The group communication system according to claim 3, further comprising a comparison / specifying unit for specifying, and performing data transmission to the relay device corresponding to the unique number specified by the comparison / specifying unit. 5. The relay device has a unique number transmitting means for transmitting its own unique number in response to a request from the terminal device, and the terminal device transmits a unique number transmission request to the relay device. And a registering means for receiving a unique number transmitted from the relay device in response to the unique number transmission request and registering the unique number in the storage means on a first-in first-out basis. The group communication system according to any one of claims 1 to 4, wherein 6. The maintenance center has a unique number transmitting means for transmitting a unique number of the relay device to the terminal device via a public network in response to a request from the terminal device. The group communication system according to claim 2, further comprising a registration unit that registers the unique number transmitted from the maintenance center in the storage unit. 7. When a relay device registered in the storage device fails, the terminal device has a failure in the storage device by a unique number notified from the maintenance center via another relay device. 3. The apparatus according to claim 2, further comprising a unique number updating means for rewriting the unique number of the relay device.
Or the group communication system according to claim 6. 8. The terminal device stores an identification number of the maintenance center in the storage unit, and an identification number included in a reception process from the maintenance center matches an identification number in the storage unit. 8. The group communication system according to claim 2, wherein data is received from the maintenance center only when the communication is performed. 9. The maintenance center and the terminal device each include:
8. The communication device according to claim 2, further comprising an encryption unit for encrypting the transmission data and a decryption unit for decrypting the encrypted reception data, and performing the mutual communication by the encrypted data. Or the group communication system according to claim 8.