JPH0923185A - Radio communication system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a radio communication system prevented from being easily influenced by. other radio systems and capable of reducing the power consumption of a slave equipment. SOLUTION: Respectively different channels (frequency) f1 to f3 are allocated to respective slave equipments (slaves) 11a to 11c. In the case of calling the slave 1b from a master equipment (master) 9, a starting message 15 is transmitted through the channel f2 for 23 seconds. Each of the slaves 11a to 11c executes carrier sensing at a 20-sec interval, the slave 11b is turned to a receiving state, reads out the message 15 and then returns a response message 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless communication system used for automatic meter reading of gas, water, electricity and the like.

[0002]

2. Description of the Related Art Recently, an automatic meter reading system for sending meter reading values of a gas meter to a center via a public line is being developed. Then, in an apartment house or the like, it may be possible to wirelessly communicate a part thereof. For example, a wireless slave unit (slave unit) is attached to each meter of an apartment house, and a wireless master unit (slave unit) is attached to the management room, and the slave unit and the master unit communicate with each other. The master unit is connected to the center via a public line, and the meter reading value of the meter is sent to the center.

By the way, in such a system, in order to reduce the power consumption, the master unit and the slave unit are driven intermittently. That is, the master unit and the slave unit perform carrier sense intermittently, and if there is a radio wave, start receiving operation. As described above, there are methods shown in FIGS. 7 and 8 as a method of intermittently performing carrier sensing.

FIG. 7 is an explanatory diagram of a wireless communication system called an asynchronous continuous transmission system. A case where communication is performed between the master 115 and the three slaves 117a, 117b, 117c will be described. Base unit 115 performs carrier sensing at frequency f1 once every 20 seconds. Slave unit 1
Similarly, 17a, 117b, and 117c perform carrier sensing at a frequency f1 once every 20 seconds. For example, when calling a meter (not shown) to which the child device 117b is connected from a center (not shown), the parent device 115 is
The activation message 119 having the frequency f1 is transmitted for a second. The ID of the meter to which the cordless handset 117b is connected is placed in the activation message f1.

The cordless handsets 117a, 117b, 117c have two
Since carrier sensing is performed at the frequency f1 at a rate of once every 0 seconds, both of them enter the reception state, and the activation message 11
Read the ID in 9 and the ID of the meter connected to you
It is determined whether or not. Since the ID in the activation message 119 is the ID of the meter connected to itself, the child device 117b returns the response message 121 to the parent device 115 at the frequency f1. afterwards,
Communication is performed between the master unit 115 and the slave unit 117b.

FIG. 8 is an explanatory diagram of a wireless communication system called a synchronous ACK-NACK system. The master unit 215 and the slave units 217a, 217b, 217c perform carrier sensing at the frequency f1 once every 20 seconds. Base unit 215
The slave units 217a, 217b, and 217c are synchronized with each other. For this reason, the master unit 215 and the slave units 217a, ... Perform communication for clock adjustment once every 10 minutes.

When the center (not shown) calls a meter (not shown) connected to the child device 217b, the parent device 215
Sends an activation message 219 carrying the ID of the meter connected to the handset 217b. Since the slave units 217a, ... Execute carrier sensing at the frequency f1 respectively, the slave unit 217b starts receiving operation, and the slave unit 217b receives the ACK (Acknowle) because the ID in the activation message 219 is the ID of the meter connected to itself.
dge) to the master device 215. After that, the channel is changed between the master unit 215 and the slave unit 217b, and communication is performed at the frequency f2.

[0008]

However, as shown in FIG.
In the communication method shown in FIG. 8, when another wireless system communicates at the same frequency f1 as the wireless system, there is a problem that communication congestion or the like occurs.

Further, even in the case of communication within the wireless system, there is a problem that as the frequency of communication increases, the carrier sense of the handset which is not involved in the communication increases and the power consumption of the handset increases. . For example, in the case of the wireless communication system shown in FIG. 7, when the master unit 115 and the slave unit 117b communicate with each other on the channel (frequency) f1, other slave units 117a,
Since 117c also carries out carrier sensing, it enters a receiving operation and causes an increase in power consumption. In particular, a wireless system for automatic meter reading requires high communication reliability. In addition, hardware that is as inexpensive as possible is required, and the child device is driven by a battery. Due to these circumstances, the above problems have become important issues to be solved.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a wireless communication system that is less likely to be affected by other wireless systems and that consumes less power as a slave unit. is there.

[0011]

In order to achieve the above-mentioned object, a first aspect of the invention is to perform wireless communication between one wireless master device and a plurality of wireless slave devices, and to communicate with the wireless master device. A plurality of wireless slave devices are wireless communication systems that perform carrier sense intermittently, different channels are assigned to the plurality of wireless slave devices, and the wireless master device and the wireless slave devices perform communication asynchronously. It is a wireless communication system characterized by the above. A second aspect of the present invention is a wireless communication system in which wireless communication is performed between one wireless master device and a plurality of wireless slave devices, and the wireless master device and the plurality of wireless slave devices perform carrier sense intermittently. A wireless communication system is characterized in that different time slots are respectively assigned to the plurality of wireless slave devices, and the wireless master device and the wireless slave devices perform communication in synchronization with each other. A third aspect of the present invention is a wireless communication system in which wireless communication is performed between one wireless master device and a plurality of wireless slave devices, and the wireless master device and the plurality of wireless slave devices perform carrier sense intermittently. A wireless communication system is characterized in that different channels are respectively assigned to the plurality of wireless slave devices, and the wireless master device and the wireless slave devices perform communication asynchronously. A fourth invention is a wireless communication system in which wireless communication is performed between one wireless master device and a plurality of wireless slave devices, and the wireless master device and the plurality of wireless slave devices perform carrier sense intermittently. There is provided a plurality of control channels to the plurality of wireless slave devices, and the wireless master device and the wireless slave device perform communication in synchronization with each other. A fifth invention is a wireless communication system in which wireless communication is performed between one wireless master device and a plurality of wireless slave devices, and the wireless master device and the plurality of wireless slave devices intermittently perform carrier sense. Therefore, different time slots are assigned to the plurality of wireless slave devices, the time slots are divided into a plurality of control channels, and the wireless master device and the wireless slave device perform communication in synchronization with each other. It is a characteristic wireless communication system.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a schematic configuration diagram of a wireless communication system according to a first embodiment of the present invention. This wireless communication system includes a center 1, an exchange 3, a public line 5 and a terminal side network control unit (T-NCU) 7. , Parent machine 9, child machine 11a,
11b, ..., Meters 13a, 13b ,.

The center 1 sends, for example, a telegram for automatic meter reading, and collects meter reading values and the like from the meters 13a, .... The T-NCU 7 is connected to the base unit 9 and performs automatic communication control and the like. The base unit 9 and the T-NCU 7 are installed in, for example, a management room such as an apartment. Meter 13a,
... is a gas meter, water meter, or electricity meter for each consumer such as an apartment. The wireless slave units (slave units) 11a, ... Are connected to the respective meters 13a ,.
.. and the base unit 9 are wirelessly communicated with each other.

In each of the embodiments described below, in order to simplify the description, three slave units 11a, 11b, 11 are used.
c will be taken up and the processing for calling the meter 13b from the center 1 will be described. FIG. 2 is an explanatory diagram of communication in the first embodiment. The first embodiment may be referred to as a channel assignment asynchronous continuous transmission scheme. In this embodiment,
A channel is assigned to each of the slaves 11a, 11b, ..., Asynchronous communication is performed between the master 9 and each of the slaves 11a ,.

The base unit 9 has frequencies f1, f2,
Carrier sense is performed three times at f3. Also, the handset 11a
Performs carrier sensing on the channel (frequency) f1 once every 20 seconds. Similarly, the cordless handsets 11b and 11c have channels (frequency) f2, once every 20 seconds, respectively.
Carrier sense is performed at f3.

When there is a call from the center 1 to the meter 13b, the base unit 9 transmits the activation message 15 carrying the ID of the meter 13b on the channel (frequency) f2 for 23 seconds. The slaves 11a and 11c have channels (frequency) f, respectively.
Carrier sense is performed at 1 and f3, and start message 1
Since the frequency of No. 5 is f2, the slaves 11a and 11c do not enter the receiving state.

Since the slave unit 11b performs carrier sensing on the channel (frequency) f2, it enters the state of receiving the activation message 15, reads the ID in the activation message 15, and then returns the response message 17 to the master unit 9. After that, Parent 9 and cordless handset 1
1b communicates on the communication channel (frequency) f2. Therefore, the slave unit 11 is transmitted by the communication of the channel f2.
a, the handset 11c never enters the receiving state.

When the parent machine 9 only needs to call the child machine 11b, the ID of the meter 13b is included in the activation message 15.
There is no need to put. Further, when the terminal 13 makes a call, for example, when the meter 13a calls the center 1, if the handset 11a transmits an activation message for 23 seconds at the frequency f1, the parent device 9 carries out carrier sense and transmits the activation message. read.

FIG. 3 is an explanatory diagram of communication in the second embodiment. The second embodiment is a time slot allocation synchronization A
It is a wireless communication system that can be called a CK-NACK system. That is, time slots are assigned to the slaves 11a, 11b, ... And the master 9 and the slaves 11a ,. The clock adjusting communication is performed n times (n is the number of child devices) in the master unit 9 every 10 minutes, and about once in the n minutes in the slave unit.

The slave units 11a, 11b, ... Are assigned different time slots, and carrier sensing is performed once every 20 seconds. In addition, the base unit 9 performs carrier sense three times in 20 seconds. In addition, base unit 9 and handset 1
.. perform carrier sensing on the same channel (frequency) f1.

When the center 1 receives a command to the meter 13b to make a call, the base unit 9 waits until the handset 11b carries out carrier sense, and the start message 25 is sent at the timing when the handset 11b carries out carrier sense. To send. The ID of the meter 13b is placed in the activation message 25.

Since the slave unit 11b is performing carrier sensing at this timing, it enters the receiving state, and the activation message 2
5 is read, the ID of the meter 13b is recognized, and ACK is transmitted. After that, the master unit 9 and the slave unit 11b change the communication channel and perform communication on the channel (frequency) f2. Therefore, the slave unit 11 is transmitted by the communication of the channel f2.
a, the handset 11c never enters the receiving state.

When making a terminal call, for example, when the handset 11a calls the center 1, the handset 11a communicates with the center 1 using its own time slot to communicate with the base 9.

FIG. 4 is an explanatory diagram of communication in the third embodiment. The third embodiment can be called an asynchronous continuous transmission system with a plurality of channels assigned, and a plurality of channels are assigned to each slave unit in the first embodiment.

That is, the slave 11a is assigned channels (frequency) f1 and f2, the slave 11b is assigned channels (frequency) f3 and f4, and the slave 11c is assigned channels (frequency) f5 and f6. Assigned. The handset 11a has a channel (frequency) at a rate of once every 20 seconds.
Carrier sense is performed at f1 and f2. Handset 11b, 1
Similarly, 1c performs carrier sensing on channels (frequency) f3 and f4 and channels (frequency) f5 and f6. The base unit 9 has channels (frequency) f1, f2, ... For 20 seconds.
... Carrier sense is performed at f5 and f6.

When calling the meter 13b from the center 1, the base unit 9 transmits the activation message 35 having the ID of the meter 13b mounted therein, for example, on the channel (frequency) f4 for 23 seconds. Since the slave unit 11b performs carrier sensing on the channel (frequency) f4, it enters the receiving state, reads the meter ID in the activation message 35, and then sends the response message 37 to the master unit 9 on the channel (frequency) f4. After that, the master 9 and the slave 11b communicate with each other on the channel (frequency) f4. Therefore, the slave unit 11a and the slave unit 11c do not enter the receiving state by the communication of the channel f4.

When making a call from the terminal, for example, the handset 11a
When calling the center 1, the activation message is transmitted using the channel (frequency) f1. The base unit 9 performs carrier sense, reads this activation message, and the handset 11a is connected to the center 1.

FIG. 5 is an explanatory diagram of communication in the fourth embodiment. The fourth embodiment is a multiple control channel allocation synchronization A.
This is called the CK-NACK method, and a plurality of control channels are assigned to the master 9 and the slaves 11a, 11b, .... The master 9 and each slave 11a communicate with each other in synchronization. The clock setting communication is performed by the master unit 9 and each slave unit 11a, ...
Both are done about once every 10 minutes.

The master unit 9, the slave units 11a, ...
Carrier sensing is performed on the channels (frequency) f1 and f2 at a rate of 100 degrees. When calling the meter 13b from the center 1, when the master unit 9 receives an instruction from the center 1, the master unit 9 waits until the timing for carrier sensing, and then the meter 13b.
The activation message 45 having the ID of b is transmitted on the channel (frequency) f2.

Since the slave units 11a, 11b and 11c perform carrier sensing on the channel (frequency) f2, they enter the receiving state and read the meter ID in the activation message 45. The cordless handset 11b is the ID of the meter 13b to which it is connected.
And ACK is returned to the master unit 9. Cordless handset 11
a, the handset 11c is connected to its own meter 13a, 13
No response is returned because it is not the ID of c. After that, base unit 9
And cordless handset 11b change channel, channel (frequency)
Communication is performed at f3. Therefore, the slave unit 11a and the slave unit 11c do not enter the receiving state by the communication of the channel f3.

When making a call from the terminal, for example, the handset 11a
When the user calls the center 1, the handset 11a sends an activation message for calling the base 9 to the channel (frequency) f1 or f.
2, and the base unit 9 receives this and the handset 11b is connected to the center 1.

FIG. 6 is an explanatory diagram of communication in the fifth embodiment. The fifth embodiment can be called a multiple control channel, time slot assignment synchronous ACK-NACK system, in which a communication time slot is assigned to each child device and a plurality of control channels are provided in the time slot.
The clock adjustment communication is performed by the master device 9 n times within 10 minutes, and each slave device 1
1a, ... Is performed about once every n minutes.

Different time slots are assigned to the slave units 11a, 11b, and 11c, and two channels (frequency) f1 and f2 are provided in the time slots. The handset 11a performs carrier sensing on the channels (frequency) f1 and f2 at a rate of once every 20 seconds.

The slave unit 11b has a channel (frequency) f at a rate of once every 20 seconds at a timing different from that of the slave unit 11a.
Carrier sense is performed at 1 and f2. The child device 11c performs carrier sensing on the channels (frequency) f1 and f2 at a rate of once every 20 seconds at a timing different from those of the child devices 11a and 11b. The base unit 9 performs carrier sensing on the channels (frequency) f1 and f2 three times in 20 seconds. The master 9 and the slaves 11a, ... Are communicated in synchronization with each other.

When the center 1 calls the meter 13b,
The master unit 9 reads the command from the center 1 and waits until the communication with the slave unit 11b is performed, and then the meter 13
The activation telegram 55 having the ID of b is transmitted on the channel (frequency) f2. Since the child device 11b performs carrier sensing on the channel (frequency) f2, it reads the meter ID in the activation message 55 and returns ACK to the parent device 9. After that, the communication channel is changed between the master unit 9 and the slave unit 11b, and communication is performed on the channel (frequency) f3.
Therefore, the communication of the channel f3 causes the cordless handset 11
a, the handset 11c never enters the receiving state.

When making a call from the terminal, for example, the handset 11a
Call the center 1, the handset 11a transmits an activation message to the base unit 9 on the channels (frequency) f1 and f2 using its own time slot, and the handset 11a is connected to the center 1.

As described above, according to each embodiment of the present invention,
Even if another wireless communication system exists in the vicinity, it is possible to reduce interference from the other wireless communication system, and a child caused by an increase in carrier sense of a handset due to an increase in communication events in the wireless communication system according to the present invention. It is possible to suppress an increase in power consumption of the machine.

In the first and third embodiments, the activation telegrams 15 and 35 are transmitted for 23 seconds, but if the timing at which the other party carries out carrier sensing is known, that timing will be set. The activation message may be transmitted. In this case, as an opportunity to adjust the timing, it is possible to adjust the timing each time communication is performed. However, even if the timing is adjusted, the parent device 9 and the child device 11a,
The clocks 11b, ... Have time lags with the passage of time. Therefore, the transmission length of the activation message is adjusted by taking into account the maximum clock offset according to how much time has passed since the time when the timing was last adjusted.

Further, in the first embodiment, the base unit 9 carries out carrier sensing three times at the frequencies f1, f2 and f3 for 20 seconds. By the way, adjacent frequencies are selected as the frequencies f1, f2, and f3, and a wide band filter is used for the base unit 9 so that carrier sensing can be performed once regardless of the frequencies f1, f2, and f3. May be. In this way, the carrier sense only needs to be performed once every 20 seconds, so that the power consumption of the base unit 9 can be reduced. This can be applied to the parent device 9 and the child devices 11a, ... In the third, fourth and fifth embodiments.

Further, in each of the third, fourth and fifth embodiments, three or more channels (frequency) may be assigned to the slave unit. For example, in the fourth embodiment shown in FIG. 5, channels (frequency) of f1, f2, and f3 are assigned to the master unit 9 and each slave unit 11a, ....

[0041]

As described above in detail, according to the present invention, it is possible to provide a wireless communication system that is less likely to be affected by other wireless systems and that consumes less power than a slave unit.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a wireless communication system.

FIG. 2 is an explanatory diagram of communication in the first embodiment.

FIG. 3 is an explanatory diagram of communication in the second embodiment.

FIG. 4 is an explanatory diagram of communication in the third embodiment.

FIG. 5 is an explanatory diagram of communication in the fourth embodiment.

FIG. 6 is an explanatory diagram of communication in the fifth embodiment.

FIG. 7 is an explanatory diagram of communication in a conventional wireless communication system.

FIG. 8 is an explanatory diagram of communication in a conventional wireless communication system.

[Explanation of symbols]

 1 ... Center 3 ... Switch 5 ... Public line 7 ... T-NCU 9 ......... Main unit 11 ......... Slave unit 13 ......... Meter

Claims (9)

[Claims] 1. A wireless communication system for performing wireless communication between one wireless master device and a plurality of wireless slave devices, wherein the wireless master device and the plurality of wireless slave devices are wireless communication systems that perform carrier sense intermittently. Then, a different channel is assigned to each of the plurality of wireless slave devices, and the wireless master device and the wireless slave device perform communication asynchronously. 2. A wireless communication system for performing wireless communication between one wireless master unit and a plurality of wireless slave units, wherein the wireless master unit and the plurality of wireless slave units are wireless communication systems that perform carrier sense intermittently. Then, a different time slot is assigned to each of the plurality of wireless slave devices, and the wireless master device and the wireless slave device perform communication in synchronization with each other. 3. A wireless communication system for performing wireless communication between one wireless master device and a plurality of wireless slave devices, wherein the wireless master device and the plurality of wireless slave devices are wireless communication systems that perform carrier sense intermittently. A plurality of different channels are respectively assigned to the plurality of wireless slave devices, and the wireless master device and the wireless slave devices perform communication asynchronously with each other. 4. A wireless communication system that performs wireless communication between one wireless master device and a plurality of wireless slave devices, and the wireless master device and the plurality of wireless slave devices are wireless communication systems that perform carrier sense intermittently. Then, a plurality of control channels are given to the plurality of wireless slave devices, and the wireless master device and the wireless slave devices perform communication in synchronization with each other. 5. A wireless communication system for performing wireless communication between one wireless master device and a plurality of wireless slave devices, wherein the wireless master device and the plurality of wireless slave devices are wireless communication systems that perform carrier sense intermittently. A different time slot is assigned to each of the plurality of wireless slave devices, the time slot is divided into a plurality of control channels, and the wireless master device and the wireless slave device perform communication in synchronization with each other. Wireless communication system. 6. The wireless master device is connected to a center via a public line, the wireless slave device is connected to a terminal device, and communication is performed between the center and the terminal device. To the wireless communication system according to claim 5. 7. The wireless communication system according to claim 6, wherein the terminal device is a gas meter. 8. The wireless communication system according to claim 6, wherein the terminal device is an electric meter. 9. The wireless communication system according to claim 6, wherein the terminal device is a water meter.