Patent Description:
In utilities such as gas, electric power, and water, a wireless automatic meter reading system has been put into practical use, which automatically reads a meter reading value of a meter for measuring the usage amount by using wireless communication or the like.

Such wireless automatic meter reading is composed of a wireless terminal attached to the meter for receiving the meter reading value from the meter, a host terminal for transmitting the meter reading value obtained from the wireless terminal to a center system of a utility company, and the like. The wireless terminal may be built in the meter as a wireless unit.

There are various communication systems, such as a specified low-power wireless system that uses a license-free frequency band, and a system that uses cellular-based communication that a telecommunications carrier handling mobile phones, etc. secures a band and operates.

If the specified low-power wireless system is used, since it uses a license-free band, the cost for the communication channel is suppressed, but the labor required to construct and maintain the network has been a problem.

On the other hand, recently, telecommunications carriers have come to provide cellular systems suitable for sensor networks. In this case, although cost is required for the communication channel, network construction and maintenance are performed under certain conditions by the telecommunications carrier, which is one of the merits in constructing the sensor network.

However, a wireless terminal using cellular-based communication needs to be connected to a base station or the like, which tends to increase current consumption.

In particular, a wireless terminal for automatic meter reading related to gas or water often uses a battery as a power source, and it is becoming very important to suppress current consumption. Therefore, for example, as disclosed in Unexamined <CIT>, there is a system in which depending on a communication environment, a terminal determines whether or not to transmit, if the environment is good, transmits data, and if it is not good, stores data, thus suppressing power consumption.

<CIT> discloses a system and method for prioritized collection of meta readings and that a set of parameters such as transmission frequency or the length of a reporting window can be tuned.

<CIT> discloses a system for RF transmission power adjustment in a wireless sensor is provided. The system includes a main control unit positioned within an environment. At least one sensor is positioned within the environment and constructed and arranged to monitor occurrences within the environment. The at least one sensor is in wireless communication with the main control unit. The at least one sensor sends signals to the main control unit indicative of the occurrences. The signals have communication parameters affected by an environmental condition of the environment. The main control unit regulates a RF transmission power of the at least one sensor based on at least one of an aggregate of communication parameters of the signal or the environmental condition.

However, the conventional method has a problem that the date and time when data can be sent cannot be specified and that the data cannot be sent unless the communication environment is improved. There are also problems that cannot be dealt with by the cellular communication.

That is, in the cellular-based communication, the communication situation is determined between the base station, which is a host device, and the wireless terminal, the transmission power between the base station and the wireless terminal and a number of retransmissions are changed in accordance with the communication situation to ensure the reliability of communication, and even if communication is possible, the current consumption increases, which does not lead to suppression of the current consumption.

Further, since the wireless terminal for automatic meter reading is installed together with the meter, it serves as a fixed station whose position is fixed. Therefore, once the communication environment at the installation location deteriorates, the situation often does not improve, and there is a limit to suppressing current consumption by the conventional method of sending data to the center system, after the communication environment becomes good.

Since the present disclosure changes the communication frequency and the amount of information to be communicated according to the communication situation between the wireless terminal and the host device such as a base station to suppress the current consumption, even in a case of using cellular-based communication, it becomes possible to operate while suppressing the current consumption in a communication using not a mobile station but a fixed station.

A wireless device of the present disclosure includes a communication unit that communicates with a host device, a controller that controls the communication unit, and a storage unit that records information obtained from a sensor. When information is transmitted to the host device via the communication unit, the controller changes at least of (i) a frequency of transmission and (ii) data amount of the transmission in accordance with a communication level obtained from the host device.

Further, the communication system of the present disclosure has a wireless device including a storage unit that stores information from a sensor and communication specifications with a host device, a communication unit for communicating with the host device, and a controller that controls the communication unit according to the communication specifications stored in the storage unit. Further, the communication system has the host device including a host communication unit for communicating with the wireless device, a determination unit that determines a communication level by determining the communication situation with the wireless device, and a communication interface unit that communicates with the center device. In addition, the communication system has the center device including a center communication unit that communicates with the host device and a communication specification data generator. Furthermore, the center device generates communication specification data for changing the communication specifications of the wireless device based on the communication level obtained via the center communication unit.

Since the wireless device of the present disclosure changes the communication frequency and the amount of information to be communicated according to the communication situation between the wireless device and the host device such as a base station to suppress the current consumption, even in a case of using cellular-based communication, it becomes possible to operate while suppressing current consumption.

Exemplary embodiments will now be described below in detail with reference to the drawings. However, descriptions in more detail than necessary may be omitted. For example, detailed descriptions of already well-known matters or duplicate descriptions of substantially identical configurations may be omitted.

Note that the attached drawings and the following description are provided for those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter as described in the appended claims.

First exemplary embodiment will be described below with reference to <FIG> is a block diagram showing a wireless device according to the present disclosure and a host device that communicates with the wireless device.

Wireless device <NUM> includes communication unit <NUM>, controller <NUM>, storage unit <NUM>, and power supply unit <NUM>. Hereinafter, each block of <FIG> will be described first.

Communication unit <NUM> is controlled based on a communication protocol held by controller <NUM>, performs wireless communication with host device <NUM>, transmits data and the like recorded in storage unit <NUM> to host device <NUM>, and receives instructions, etc. from host device <NUM>.

In addition, communication unit <NUM> is configured by respective circuits for setting a transmission output, selecting a channel to be transmitted, setting a transmission rate for transmission, and performing modulation or the like when performing wireless communication.

Controller <NUM> holds information for controlling communication unit <NUM>. The information for controlling communication unit <NUM> mentioned here is a communication protocol between wireless device <NUM> and host device <NUM>. In this communication protocol, for example, as a transition of communication, from wireless device <NUM>, at a predetermined timing, wireless device <NUM> is activated into a state capable of transmission, and the data of sensor <NUM> or the like stored in storage unit <NUM> is transmitted via communication unit <NUM>. After that, there is a procedure for transitioning communication unit <NUM> to a reception state in order to receive a response from host device <NUM>. In addition to this, controller <NUM> has a program and the like for controlling entire wireless device <NUM>. Host device <NUM> has determination unit <NUM> that determines the communication level by determining the communication situation with wireless device <NUM>, and the communication level determined by determination unit <NUM> is transmitted to wireless device <NUM>. Controller <NUM>, if the communication level obtained via communication unit <NUM> is smaller than a predetermined level, sets the frequency at which wireless device <NUM> transmits to host device <NUM> to be small, and if the communication level is larger than a predetermined level, sets the communication frequency to be large. Note that, the communication level is calculated by combining, depending on the network configuration, one or more indicators, such as the reference signal reception power, the reference signal reception quality, the reception signal code power, the transmission power, the reception interference power, and the reception signal strength indicator in the communication between host device <NUM> and wireless device <NUM>.

Storage unit <NUM> stores data obtained from external sensor <NUM> connected to wireless device <NUM>. Sensor <NUM> is, for example, a flow meter such as a gas meter or a water meter, and outputs an integrated value of flow rate or an instantaneous flow rate value.

Power supply unit <NUM> holds electric power to be supplied to each block in wireless device <NUM> and is composed of a battery.

Next, a flow for determining the communication frequency in controller <NUM> of wireless device <NUM> will be described using the flowchart for explaining the communication operation of wireless device <NUM> shown in <FIG>.

Wireless device <NUM> is driven by power supply unit <NUM> composed of a battery and the like, and in order to save power as much as possible, communication unit <NUM> and the like save power when communication is unnecessary. Therefore, when starting the communication start flow of <FIG>, first, wireless device <NUM> is activated (step S101). Then, communication with host device <NUM> is started in accordance with a predetermined communication protocol (step S102). After the communication is started, the data including the communication level is received from host device <NUM> (step S103). After that, controller <NUM> sets the communication frequency at which wireless device <NUM> transmits data to host device <NUM> in accordance with the communication level obtained by reception (step S104). The communication frequency is set in accordance with the communication level and the required battery life.

Table <NUM> shows three levels indicating the communication levels determined by the data received from host device <NUM>, and one example of a number of retransmissions in accordance with the communication situation in one-time communication, the expected battery life, and the communication frequency set by comparison determination by controller <NUM>.

In Table <NUM>, regarding the communication level, level <NUM> indicates the best communication situation, and level <NUM> indicates the worst communication situation. In cellular communication, the number of retransmissions in one-time communication is set as a fixed value in accordance with the communication level determined by the communication situation, and as the communication situation worsens, the number of retransmissions increases and current consumption increases. Therefore, in a case of one-time transmission per day, the battery life becomes shorter as the communication situation becomes worse.

Therefore, controller <NUM> determines the communication level to set the communication frequency for achieving the required battery life. In the example shown in Table <NUM>, in order to achieve a battery life of <NUM> years, the communication frequency is once a day when the communication level is level <NUM>, once every two days when the communication level is level <NUM>, and once every <NUM> days when the communication level is level <NUM>. Therefore, for example, when the communication level is determined to be level <NUM>, the communication frequency is set to once every two days.

However, if daily data is required and the communication frequency is once every two days, it goes without saying that measurement data for two days should be saved and data for two days should be transmitted with one-time communication. Table <NUM> is an example showing that the current consumption required for one-time communication varies depending on the communication situation, and a number of communication levels and the number of retransmissions for each level are determined as the specifications of the communication system. Furthermore, it is also possible to change the transmission power for each communication level instead of the number of retransmissions, or change both the number of retransmissions and the transmission power, and both are determined as the specifications of the communication system. The battery life and the set communication frequency are determined by the current consumption and the battery capacity.

Further, in the present exemplary embodiment, the communication level is obtained by receiving from host device <NUM>, but it goes without saying that the communication level may be determined by wireless device <NUM> determining the communication situation.

Also, when the battery life for <NUM> years is enough, the communication frequency is once a day if the communication level is level <NUM>, but, for example, in the case of level <NUM>, the communication frequency is twice a day. If the communication situation is good, the responsiveness is improved by increasing the communication frequency, and thus, the communication frequency can be set in accordance with the communication situation and the required battery life. In particular, when communication is started based on a call origination from the wireless device, a command from host device <NUM> or a center device (not shown) connected to host device <NUM> and an instruction to the wireless device or a sensor such as a meter connected to the wireless device can be performed at an early stage, which is useful.

As described above, according to the present exemplary embodiment, since the communication frequency is changed to suppress the current consumption in accordance with the communication situation between wireless device <NUM> and host device <NUM> such as a base station, even when the cellular-based communication is used, it is possible to operate while suppressing the current consumption.

Next, a second exemplary embodiment will be described with reference to <FIG> is a block diagram showing a wireless device according to the present disclosure and a host device that communicates with the wireless device. The same constituent elements described in <FIG> are indicated by the same numbers. The difference from the first exemplary embodiment is that controller <NUM> sets the amount of information to be communicated in accordance with the communication level.

That is, in the present exemplary embodiment, if the communication level is smaller than a predetermined communication level, controller <NUM> sets an amount of information to be transmitted once by wireless device <NUM> to host device <NUM> to be small, and if the communication level is larger than a predetermined communication level, sets the amount of information to be transmitted once by wireless device <NUM> to host device <NUM> to be large.

Next, a flow for determining the amount of information of communication in controller <NUM> of wireless device <NUM> will be described using the flowchart for explaining the communication operation of wireless device <NUM> shown in <FIG>.

When the communication start flow of <FIG> is started, first, wireless device <NUM> is activated (step S101). Then, communication with host device <NUM> is started in accordance with a predetermined communication protocol (step S102). After the communication is started, the data including the communication level is received from host device <NUM> (step S103). After that, controller <NUM> sets the amount of information that wireless device <NUM> transmits data to host device <NUM> in accordance with the communication level (step S105). The amount of information of communication is set in accordance with the communication level and the required battery life. Table <NUM> shows three levels indicating the communication levels, and one example of a number of retransmissions in accordance with the communication level, the expected battery life, and the amount of information per communication set by comparison determination by controller <NUM>.

Therefore, controller <NUM> sets the amount of information to be transmitted in one-time communication to achieve the required battery life by determining the communication level. In the example shown in Table <NUM>, in order to achieve a battery life of <NUM> years, if the communication level is level <NUM>, the amount of information is <NUM> pieces at a time (corresponding to a number of pieces of measured data for one day every one hour by sensor <NUM>). If the communication level is level <NUM>, the amount of information is <NUM> pieces at a time (corresponding to the number of pieces of measured data for one day every <NUM> hours by sensor <NUM>). If the communication level is level <NUM>, the amount of information is <NUM> pieces at a time (corresponding to the number of pieces of measured data for one day every <NUM> hours by sensor <NUM>). Therefore, for example, when the communication level based on the communication situation data is determined to be level <NUM>, the amount of information transmitted in one-time communication is set to <NUM> pieces.

Further, as a method of reducing the amount of information, a method of selecting necessary data in accordance with the communication level among the data obtained from sensor <NUM> may be used. That is, when sensor <NUM> is a gas meter and there is a gas flow rate, a gas pressure, and a gas temperature as hourly data, only the gas flow rate and the gas pressure are transmitted, or only the gas flow rate is transmitted. In this way, the amount of information may be reduced.

Table <NUM> shows an example, and a number of communication levels and the number of retransmissions are determined as the specifications of the communication system. Further, it is also possible to change the transmission power for each communication level instead of the number of retransmissions, change both the number of retransmissions and the transmission power, and further change the number of retransmissions and the transmission power in combination with the transmission rate and the modulation method, and both are determined as the specifications of the communication system. In addition, the battery life and the set amount of information are determined by the current consumption and the battery capacity.

In the present exemplary embodiment, host device <NUM> has been described as having determination unit <NUM> that determines the communication level, but wireless device <NUM> may determine the communication level by determining the communication situation.

As described above, according to the present exemplary embodiment, according to the communication situation between wireless device <NUM> and host device <NUM> such as a base station, the amount of information transmitted per communication is changed to suppress the current consumption. With this configuration, it is possible to operate while suppressing current consumption even when using cellular-based communication. Therefore, the configuration of the present exemplary embodiment is particularly effective when the amount per piece of data is large, the transmission data length is long, and the power consumption required for transmitting one piece of data is large.

In the first exemplary embodiment described above, the configuration that changes the communication frequency according to the communication level is described, and in the present exemplary embodiment, the configuration that changes the amount of information to be transmitted per communication in accordance with the communication level has been described. However, a configuration that appropriately selects from two of the communication frequency and the amount of information to be transmitted per communication in accordance with the communication level, or sets both at the same time may be used.

That is, when high-speed communication is possible, since the influence of power consumption on the amount of information is small, the configuration that changes the communication frequency described in the first exemplary embodiment can be adopted, and in the case of low-speed communication, since the influence of power consumption on the amount of information is large, the configuration that changes the amount of information transmitted per communication can be adopted.

Further, both the communication frequency and the amount of information transmitted per communication may be changed in accordance with the required amount of information and the required frequency. That is, as shown in Table <NUM>, the communication frequency and the amount of information in one-time communication may be varied in accordance with the communication level. For example, in the case of level <NUM>, <NUM> pieces of data can be transmitted once every <NUM> days, but when data once every <NUM> days is required, if <NUM> pieces of data, for example, can be transmitted while focusing on the required amount of information, one-time communication every two days can be achieved.

A third exemplary embodiment will be described below with reference to <FIG> and <FIG>. <FIG> is a block diagram showing a communication system in the present exemplary embodiment. The communication system according to the present exemplary embodiment includes the wireless device according to the first or second exemplary embodiment, a host device that communicates with the wireless device, and a center device.

Wireless device <NUM> includes communication unit <NUM>, controller <NUM>, storage unit <NUM>, and power supply unit <NUM>.

Communication unit <NUM> is controlled based on the communication protocol held by controller <NUM>, performs wireless communication with host device <NUM>, transmits the data and the like recorded in storage unit <NUM> to host device <NUM>, and receives instructions and the like from host device <NUM>. Further, communication unit <NUM> is configured by respective circuits for setting a transmission output, selecting a channel to be transmitted, setting a transmission rate for transmission, and performing modulation, or the like when performing wireless communication.

Controller <NUM> holds information for controlling communication unit <NUM>. The information for controlling communication unit <NUM> mentioned here is a communication protocol between wireless device <NUM> and host device <NUM>. In this communication protocol, for example, as a transition of communication, from wireless device <NUM>, at a predetermined timing, wireless device <NUM> is activated into a state capable of transmission, and the data of external sensor <NUM> stored in storage unit <NUM> is transmitted via communication unit <NUM>. After that, there is a procedure for transitioning communication unit <NUM> to the reception state in order to receive a response from host device <NUM>. In addition to this, controller <NUM> holds a program and the like for controlling entire wireless device <NUM>.

Storage unit <NUM> stores data obtained from external sensor <NUM> connected to wireless device <NUM>. Sensor <NUM> is, for example, a flow meter such as a gas meter or a water meter, and outputs an integrated value of the flow rate or an instantaneous flow rate value.

Host device <NUM> includes host communication unit <NUM> that communicates with wireless device <NUM>, determination unit <NUM> that determines the communication level from the communication situation with wireless device <NUM>, and communication interface <NUM> that communicates with center device <NUM>.

Center device <NUM> includes center communication unit <NUM> that communicates with host device <NUM>, and communication specification data generator <NUM> that generates communication specification data capable of changing the communication specifications of wireless device <NUM> based on the communication level obtained from host device <NUM>.

Host device <NUM> is a base station of a cellular communication network managed and operated by a telecommunications carrier, and center device <NUM> is operated by a business operator that supplies and services utilities such as gas and water. Host device <NUM> and center device <NUM> are connected by an internet network or a public line.

Next, the operation of the communication system in the present exemplary embodiment will be described using the communication sequence diagram shown in <FIG>.

First, host device <NUM> determines the communication level based on the communication situation with wireless device <NUM> by determination unit <NUM>, and transmits the communication level to center device <NUM> (step S201, step S202). Next, center device <NUM> determines the communication specifications of wireless device <NUM> based on the communication level received from host device <NUM>, and generates communication specification data (step S203, step S204). This communication specifications define the communication frequency in accordance with the communication level shown in Table <NUM>, the amount of information in accordance with the communication level shown in Table <NUM>, the transmission power in accordance with the communication level, or the like, and are determined based on the required battery life.

Then, the communication specifications are transmitted as communication specification data to wireless device <NUM> via host device <NUM> (step S205). Wireless device <NUM> stores the received communication specification data in storage unit <NUM> (step S206, step S207), controller <NUM> controls communication unit <NUM> based on the communication specifications stored in storage unit <NUM>, transmits the sensor data or the like obtained by sensor <NUM> to center device <NUM> via host device <NUM> (step S208), and center device <NUM> receives the sensor data (step S209). In the present exemplary embodiment, the configuration has been described in which center device <NUM> directly receives the communication level determined by determination unit <NUM> of host device <NUM> from host device <NUM> (step S203), but as shown in <FIG>, wireless device <NUM> may receive the communication level from host device <NUM> and save the communication level in storage unit <NUM> (step S301), and then wireless device <NUM> may transmit the communication level alone or together with the data of sensor <NUM> to center device <NUM> via host device <NUM> (step S302). Alternatively, the transmission may be performed based on a communication level request from center device <NUM> to wireless device <NUM>.

As described above, according to the present exemplary embodiment, since center device <NUM> creates communication specifications in accordance with the communication situation between wireless device <NUM> and host device <NUM> such as a base station, and wireless device <NUM> transmits data based on this communication specifications, it becomes possible to operate while suppressing current consumption even when using cellular-based communication. In this case, since the communication specifications of wireless device <NUM> can be determined by center device <NUM>, wireless device <NUM> does not require the function of changing the communication frequency and the amount of information in accordance with the communication level as in the first exemplary embodiment and the second exemplary embodiment. Therefore, an existing wireless device can be used.

Note that, the present exemplary embodiment has been described with the configuration in which host device <NUM> has determination unit <NUM> that determines the communication level, but it goes without saying that the present exemplary embodiment can be achieved with the configuration in which wireless device <NUM> determines the communication level by determining the communication situation, and the communication level is transmitted to center device <NUM> via host device <NUM>.

As described above, the wireless device in the first aspect includes a communication unit that communicates with a host device, a controller that controls the communication unit, and a storage unit that records information obtained from a sensor, in which when the wireless device transmits the information to the host device via the communication unit, the controller changes at least of (i) a frequency of the transmission and (ii) data amount of the transmissionin accordance with a communication level obtained from the host device.

With this configuration, since the controller changes the frequency of the transmission and data amount of the transmission in accordance with the communication situation between the wireless device and the host device such as the base station to suppress the current consumption, it becomes possible to operate while suppressing current consumption even when using cellular-based communication.

The wireless device in the second aspect, particularly in the first disclosure, when the controller determines that the communication level with the host device is higher than a predetermined level, the controller may increase the frequency of the transmission.

With this configuration, when the communication situation is good, it is possible to improve the responsiveness by increasing the communication frequency while ensuring the required battery life.

The wireless device according to the third aspect, particularly in the first disclosure, when the controller determines that the communication level with the host device is lower than a predetermined level, the controller may reduce the frequency of the trannsmission.

With this configuration, when the communication situation is not good, it is possible to suppress the current consumption and ensure the required battery life.

The wireless device according to the fourth aspect, particularly in the first disclosure, when the controller determines that the communication level with the host device is higher than a predetermined level, the controller may set the data amount of the transmission to be larger than the predetermined amount.

The wireless device according to the fifth aspect, particularly in the first disclosure, when the controller determines that the communication level with the host device is lower than a predetermined level, the controller may set data amount of the transmission to be smaller than the predetermined amount.

The communication system according to the sixth as has a wireless device including a storage unit that stores information from a sensor and communication specifications with a host device, a communication unit for communicating with the host device, and a controller that controls the communication unit in accordance with the communication specifications stored in the storage unit. Further, the communication system has the host device including a host communication unit for communicating with the wireless device, a determination unit that determines a communication level by determining the communication situation with the wireless device, and a communication interface unit that communicates with the center device. In addition, the communication system has the center device including a center communication unit that communicates with the host device and a communication specification data generator. Furthermore, the center device generates communication specification data for changing the communication specifications of the wireless device based on the communication level obtained via the center communication unit.

In the communication system according to the seventh aspect, particularly in the sixth disclosure, when the determination unit of the host device determines that the communication level is higher than a predetermined level, the communication specification data generator of the center device may generate the communication specification data that is set so as to increase the communication frequency of the wireless device, and transmit the communication specification data to the wireless device via the host device.

In the communication system according to the eighth aspect, particularly in the sixth disclosure, when the determination unit of the host determines that the communication level is lower than a predetermined level, the communication specification data generator of the center device may generate the communication specification data that is set so as to reduce the communication frequency of the wireless device, and transmit the communication specification data to the wireless device via the host device.

In the communication system according to the ninth aspect, particularly in the sixth disclosure, when the determination unit of the host determines that the communication level is higher than a predetermined level, the communication specification data generator of the center device may generate the communication specification data that is set so as to increase a data amount of the information to be transmitted from the wireless device, and transmit the communication specification data to the wireless device via the host device.

In the communication system according to the tenth disclosure, particularly in the sixth disclosure, when the determination unit of the host device determines that the communication level is lower than a predetermined level, the communication specification data generator of the center device may generate the communication specification data that is set so as to reduce a data amount of information of the information to be transmitted from the wireless device, and transmit the communication specification data to the wireless device via the host device.

Claim 1:
A wireless device (<NUM>) comprising:
a communication unit (<NUM>) configured to communicate with a host device (<NUM>);
a controller (<NUM>) configured to control the communication unit (<NUM>); and
a storage unit (<NUM>) configured to record information obtained from a sensor,
characterized in that
the wireless device (<NUM>) is driven by a power supply unit (<NUM>) composed of a battery,
wherein when the wireless device (<NUM>) transmits the information to the host device (<NUM>) via the communication unit (<NUM>),
the controller (<NUM>) determines a communication level obtained from the host device (<NUM>) in comparison with a predetermined level, and
based on the determination of the communication level and required battery life, the controller (<NUM>) changes at least one of
(i) a frequency of the transmission or
(ii) data amount of the transmission,
wherein the controller is configured to determine the communication level by combining, depending on the network configuration, one or more indicators including reference signals reception power, the reference signal reception quality, the reception signal code power, the transmission power, the reception interference power, and the reception signal strength indicator in the communication between the host device (<NUM>) and wireless device (<NUM>).