Patent Application
20200288361
The disclosure of Japanese Patent Application No. 2019-039227 filed on Mar. 5, 2019 including the specification, drawings and abstract is incorporated herein by reference in its entirety.
The present invention relates to a wireless communication system, and can be suitably applied to, for example, a wireless communication system including a plurality of wireless terminals driven by a battery.
In recent years, the LPWA (Low Power Wide Area) communication system has been rapidly spreading. The LPWA communication system is characterized by a low bit rate and long communication distances, but the power consumed by the wireless terminal increases because the communication duration increases. Therefore, when a battery-driven wireless terminal performs communication over networks using the LPWA communication system, the battery is consumed more, and the battery remaining time indicating the remaining time that can be driven by the battery is shortened.
U.S. Pat. No. 9,438,311 discloses a communication process for battery-powered wireless terminals in environmentals where a low power network with low power consumption and a high power network with high power consumption exist.
However, in the related art, a clear algorithm for the determination is not described. Thus, a particular wireless terminal may continue the bridge terminal. As a result, the wireless terminal continuing the bridge terminal consumes more batteries than the other wireless terminals, so that the battery remaining time becomes shorter and the battery replacement time becomes earlier. As a result, variations occur in the battery replacement timing among the wireless terminals in the system, and the battery replacement cost of the wireless terminals in the system as a whole becomes high.
In recent years, in networks using a LPWA communication system, as communication distances are increased, the installation locations of terminals are widened, and the reduction of the battery replacement costs of wireless terminals becomes a significant problem due to the increase in the frequency of maintenance work for battery replacement of wireless terminals.
Other objects and novel features will become apparent from the description of this specification and the accompanying drawings.
According to one embodiment, a wireless communication system includes a wireless base station, a plurality of wireless terminals that communicate with the wireless base station using a first communication function, communicate with each other using a second communication function that consumes less power than the first communication function, and are driven by a battery, and a wireless controller. Based on the battery information of each of the plurality of wireless terminals, when there is a wireless terminal having a short battery remaining time, the wireless control device selects the wireless terminal as the first wireless terminal, and when the first wireless terminal is selected, the wireless control device selects the wireless terminal having a long battery remaining time as the second wireless terminal. Then, the wireless control device instructs the wireless base station and the first and second wireless terminals to change the communication path between the first wireless terminal and the wireless base station to a communication path communicating between the first wireless terminal and the wireless base station via the second wireless terminal, and to connect the first wireless terminal and the second wireless terminal by the second communication function. After receiving this instruction, the first wireless terminal transmits uplink data including at least one of battery information and communication data transmitted from the first wireless terminal to the wireless base station to the second wireless terminal using the second communication function, and the second wireless terminal transmits the uplink data to the wireless base station using the first communication function.
In addition, the second wireless terminal receives downlink data including communication data, which is transmitted from the wireless base station to the first wireless terminal, from the wireless base station using the first communication function, and transmits the downlink data to the first wireless terminal using the second communication function.
According to the above-mentioned embodiment, it is possible to contribute to the solution of the above-mentioned problem of the battery replacement cost of the wireless terminals in the system.
For clarity of explanation, the following description and drawings are appropriately omitted and simplified. In addition, the elements described in the drawings as functional blocks for performing various processes can be configured as CPUs (Central Processing Unit), memories, and other circuits in terms of hardware, and are realized by programs loaded into the memories in terms of software. Therefore, it is understood by those skilled in the art that these functional blocks can be realized in various forms by hardware alone, software alone, or a combination thereof, and the present invention is not limited to any of them. In the drawings, the same elements are denoted by the same reference numerals, and a repetitive description thereof is omitted as necessary.
Also, the programs described above may be stored and provided to a computer using various types of non-transitory computer readable media. Non-transitory computer readable media includes various types of tangible record media. Examples of non-transitory computer-readable media include magnetic recording media (e.g., flexible disks, magnetic tapes, hard disk drives), magneto-optical recording media (e.g., magneto-optical disks, CD-ROM (Compact Disc Read OnlyMemory), CD-R(CD Recordable), CD-R/W (CD ReWritable, solid-state memories (e.g., masked ROM, PROM (Programmable ROM), EPROM (Erasable PROM, flash ROM, RAM (Random Access Memory)). The program may also be supplied to the computer by various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable medium may provide the program to the computer via wired or wireless communication paths, such as electrical wires and optical fibers.
The wireless terminal 10 is driven by a battery 11. The wireless terminal 10 is a terminal that transmits communication data such as sensor data to the wireless base station 20, and is, for example, an IoT (Internet of Things) device or the like.
The wireless base station 20 is connected to a plurality of wireless terminals 10, and manages the plurality of wireless terminals 10. The wireless base station 20 and a plurality of wireless terminals 10 constitute a wide area wireless network. The wireless control device 30 is connected to the wireless base station 20, and controls communication rates, communication frequencies, communication intervals, notification contents, and the like of communications between a plurality of wireless terminals 10 and the wireless base station 20.
The wide area wireless communication circuit 13 performs wide area wireless communication (communication using the first communication function) with the wireless base station 20 on the wide area wireless network. Wide area wireless communication is wireless communication performed on wide area wireless networks such as LoRa WAN (Wide Area Network, for example, and is characterized in that the communication distances are long, but the communication rates are lower and the communication times are long, so that the consumption power is large.
The short-range wireless communication circuit 14 performs short-range wireless communication (communication using the second communication function) with another wireless terminal 10 located at a shorter distance than the wireless base station 20. The short-range wireless communication is characterized in that the communication distance is short as compared with the wide-area wireless communication, but the communication rate is high. The short-range wireless communication is characterized in that the power consumption is smaller than that of the wide-area wireless communication if the amount of data is the same. Further, the short-distance wireless communication has a feature that the transmission power can be reduced even at the same communication rate because the communication distance is short distance.
The battery 11 is used to drive the wireless terminal 10. The battery 11 is, for example, a dry battery, a button battery, or the like. The battery level measuring circuit 16 measures the remaining amount of the battery 11.
The sensor 12 acquires communication data (e.g., sensor data) to be transmitted to the wireless network controller 30 via the wireless base station 20. The communication data acquired by the sensor 12 is, for example, data of a gas meter, data of a power meter, data of weather, data of precipitation amount and snowfall amount, and the like. The sensor 12 may be mounted on the wireless terminal 10.
The terminal control unit 17 controls all functions in order to execute the respective functions in the wireless terminal 10. The operation of the wireless terminal 10 described below is performed by the terminal control unit 17 controlling the components in the wireless terminal 10, unless otherwise described.
Hereinafter, a flow of a procedure for changing the wireless connection of the wireless terminal 10 having a short battery remaining time in the first embodiment will be described. First, a flow performed in a state in which the bridge terminal M is not selected will be described with reference to
As shown in
Note that although the notification of the battery information is periodically performed here, the notification of the battery information may not be periodic or may be irregular. For example, in response to a request from the wireless control device 30 to each wireless terminal 10, each wireless terminal 10 may notify the wireless control device 30 of the battery information. Alternatively, each wireless terminal 10 may voluntarily notify the wireless control device 30 of the battery information in accordance with the remaining battery level of the battery 11, for example, when the remaining battery level becomes low.
Next, the wireless control device 30 calculates the battery remaining time of each of the plurality of wireless terminals 10 based on the battery information of each of the plurality of wireless terminals 10, and monitors the battery remaining time of each of the plurality of wireless terminals 10 in step S102 of
Next, the wireless control device 30 determines whether or not there is a low battery remaining-capacity terminal N (first wireless terminal) which is the wireless terminal 10 with a short battery-driven remaining-time (step S103 in
When there is no wireless terminal 10 serving as the low battery remaining capacity terminal N (No in Step S104 of
On the other hand, when the wireless terminal 10 serving as the low battery remaining capacity terminal N exists (Yes in step S104 of
Next, the wireless controller 30 selects a bridge terminal M (second wireless terminal) for bridging the communication of the wireless terminal 10 selected as the low battery remaining capacity terminal N in the step S105 of
In the selection of the bridge terminal M, for example, the wireless terminal 10 having the battery remaining time equal to or longer than the third threshold time may be selected as the bridge terminal M from the wireless terminals 10 which are selected as the low battery remaining capacity terminal N in the step S105 of
Subsequently, the wireless control device 30 changes the communication path between the low battery terminal N and the wireless base station 20 to a communication path that communicates between the low battery terminal N and the wireless base station 20 via the bridge terminal M, and instructs the wireless base station 20, the low battery terminal N, and the bridge terminal M to connect by short-distance wireless (
At this time, the wireless control device 30 may notify the communication timing and the communication rate together with the above-mentioned instructions. In this case, the communication rate may be a maximum rate at which communication can be performed between the low battery terminal N and the bridge terminal M. In addition, the low battery terminal N and the bridge terminal M may perform communication at a rate smaller than the maximum rate depending on the communication state. Thereafter, as shown in
The downlink data (including communication data) transmitted from the wireless base station 20 to the low battery remaining capacity terminal N is also transmitted through the same communication path. That is, as shown in
The bridge terminal M may simultaneously communicate the data of the bridge terminal M (including the uplink data and the downlink data) and the data of the low battery terminal N (including the uplink data and the downlink data) with the wireless base station 20, or may separately communicate the data of the bridge terminal M and the data of the low battery terminal N. Comparing the former simultaneous communication with the latter separate communication, the former simultaneous communication is advantageous in terms of reducing communication resources.
Thereafter, the wireless control device 30 returns to the step S101 of
Next, as a flow of a procedure for changing the wireless connection of the wireless terminal 10 having a short battery remaining time in the first embodiment, a flow performed in a state where the bridge terminal M has already been selected will be described with reference to
As shown in
Next, the wireless control device 30 calculates the battery remaining time of each of the plurality of wireless terminals 10 based on the battery information of each of the plurality of wireless terminals 10, and monitors the battery remaining time of each of the plurality of wireless terminals 10 in step S202 of
Subsequently, the wireless control device 30 determines the presence or absence of the low battery terminal N (step S203 in
On the other hand, when the wireless terminal 10 serving as the low battery remaining capacity terminal N exists (Yes in step S204 of
Next, in step S206 of
When the wireless terminal 10 selected as the low battery terminal N in step S205 of
On the other hand, when the wireless terminal 10 selected as the low battery terminal N in step S205 of
Subsequently, the wireless control device 30 instructs the wireless base station 20, the low battery terminal N (low battery remaining amount bridge terminal NM), and the bridge terminal M to change the communication path between the low battery terminal N (low battery remaining amount bridge terminal NM) and the wireless base station 20 to a communication path communicating between the low battery terminal N (low battery remaining amount bridge terminal NM) and the wireless base station 20 via the bridge terminal M, and to connect the low battery terminal N (low battery remaining amount bridge terminal NM) and the bridge terminal M by short-distance wireless (step S210 in
Thereafter, the wireless control device 30 returns to the step S201 of
Here, the selection of the low battery terminal N and the bridge terminal M is performed at a periodic timing for notifying the battery information, but the present invention is not limited to this. For example, an event such as a request from a client or the like may be used as a trigger to select the low battery terminal N and the bridge terminal M or the like irregularly.
Hereinafter, in the first embodiment, a method in which the wireless control device 30 grasps, for each of a plurality of wireless terminals 10, the wireless terminal 10 capable of short-range wireless connection with the wireless terminal 10 will be described. Examples of the method include the following five methods A1 to A5.
(1) Method A1: In the case where each of the plurality of wireless terminals 10 is a terminal to be fixedly installed, when installing the plurality of wireless terminals 10, the wireless control device 30 grasps the wireless terminal 10 capable of short-range wireless connection with the wireless terminal 10 for each of the plurality of wireless terminals 10 on the basis of the installation position of each of the plurality of wireless terminals 10.
(2) Method A2: Each of the plurality of wireless terminals 10 is provided with a position information grasping system such as a GPS (Global Positioning System) system, and notifies the wireless control device 30 of the location information. The wireless control device 30 grasps, for each of the plurality of wireless terminals 10, the wireless terminal 10 capable of short-range wireless connection with the wireless terminal 10 on the basis of the position of each of the plurality of wireless terminals 10.
(3) Method A3: Each of the plurality of wireless terminals confirms the communication state of the short-distance communication with the other wireless terminal 10, and notifies the wireless control device 30 of the confirmation result of the communication state. The wireless control device 30 grasps, for each of the plurality of wireless terminals 10, the wireless terminal 10 capable of short-range wireless connection with the wireless terminal 10 on the basis of the confirmation result of the communication state of the short-range communication of each of the plurality of wireless terminals 10.
(4) Method A4: In the case where each of the plurality of wireless terminals 10 can capture wireless waves of three or more wireless base stations 20, the wireless control device 30 is notified of the received power when the wireless waves are received from the three or more wireless base stations 20. The wireless control device 30 calculates the position of each of the plurality of wireless terminals 10 by using the three-point surveying method. The subsequent steps are the same as those of the method A2.
(5) Method A5: Combining the methods A1 to A4 described above. That is, it is not necessary for the wireless control device 30 to grasp the wireless terminals 10 capable of short-range wireless connection in the same manner for all the wireless terminals 10. For example, the wireless control device 30 may grasp one wireless terminal 10 by a method A1, and may grasp another wireless terminal 10 by a method other than the method A1.
Hereinafter, the method A3 will be described with reference to
First, as shown in
Hereinafter, the processing described with reference to
In the examples of
In the examples of
As described above, according to the first embodiment, the wireless control device 30 selects the wireless terminal 10 as the low battery terminal N when there is the wireless terminal 10 having the short battery remaining time based on the battery information of each of the plurality of wireless terminals 10, and selects the wireless terminal 10 having the long battery remaining time as the bridge terminal M when the low battery terminal N is selected. Then, the wireless controller 30 instructs the wireless base station 20, the low battery terminal N, and the bridge terminal M to change the communication path between the low battery terminal N and the wireless base station 20 to a communication path communicating between the low battery terminal N and the wireless base station 20 via the bridge terminal M, and to connect the low battery terminal N and the bridge terminal M by short-distance wireless. After receiving this instruction, the low battery remaining capacity terminal N transmits uplink data to be transmitted to the wireless base station 20 to the bridge terminal M using short-range wireless communication, and the bridge terminal M transmits the uplink data to the wireless base station 20 using wide-area wireless communication. In addition, the bridge terminal M receives downlink data to be transmitted to the low battery terminal N from the wireless base station 20 using wide area wireless communication, and transmits the downlink data to the low battery terminal N using short distance wireless communication.
Therefore, the small battery remaining amount terminal N having a short battery remaining time consumes less battery by performing short-range wireless communication with low power consumption, and the operation time can be increased. In addition, by performing short-range wireless communication with low power consumption in the wide area wireless network, it is possible to increase the operating time of the wireless terminal 10 as a whole system.
In addition, the bridge terminal M having a long battery remaining time consumes more batteries by performing wide area wireless communication having a large power consumption instead of the low battery terminal N, and as a result, the battery remaining time of the bridge terminal M approaches the battery remaining time of the low battery terminal N. Therefore, since the battery remaining time of the plurality of wireless terminals 10 can be made uniform, the battery replacement timing of the plurality of wireless terminals 10 can be made uniform, and the battery replacement cost of the wireless terminal 10 can be reduced.
Embodiment 2 is an example applied to various wide area wireless networks in which the number of wireless terminals 10 is large and the distance between the low battery terminal N and the bridge terminal M is long.
In this case, the wireless control device 30 instructs the wireless connection, for example, as follows. That is, the wireless control device 30 instructs the wireless base station and the wireless terminals 101 and 102 to change the communication path between the wireless terminal 102 and the wireless base station 20 to a communication path that communicates between the wireless terminal 102 and the wireless base station 20 via the wireless terminal 101, and to connect the wireless terminals 101 and 102 by short-distance wireless. In addition, the wireless control device 30 instructs the wireless base station 20 and the wireless terminals 101 to 103 to change the communication path between the wireless terminal 103 and the wireless base station 20 to a communication path communicating between the wireless terminal 103 and the wireless base station 20 via the wireless terminals 101 and 102, and to connect the wireless terminals 101 and 102 and the wireless terminals 102 and 103 by short-distance wireless.
In addition, the wireless control device 30 selects the four wireless terminals 105 to 108 as the low battery terminal N, and selects the wireless terminal 104 as the bridge terminal M of the four wireless terminals 105 to 108. However, since the distances between the wireless terminals 104 and 106 and between the wireless terminals 104 and 107 are long, the wireless control device 30 selects the wireless terminal 105 as a low battery terminal for relaying communications from a plurality of low battery terminals as a wireless terminal for relaying communications between the wireless terminals 104 and 106 and communications between the wireless terminals 104 and 107. In this case, the wireless connection instruction by the wireless control device 30 is the same as the above-described instruction. Further, the wireless terminal 104 is selected as a bridge terminal that relays communications from a plurality of low battery remaining terminals.
In addition, the wireless control device 30 selects three wireless terminals 1010 to 1012 as the low battery terminal N, and selects the wireless terminal 109 as the bridge terminal M of the three wireless terminals 1010 to 1012. In this case, the wireless connection instruction by the wireless control device 30 is the same as the above-described instruction.
In the example of
As described above, according to the second embodiment, one bridge terminal M is selected for a plurality of low battery terminals N, another wireless terminal 10 relays communication between the low battery terminal N and the bridge terminal M, or a plurality of bridge terminals are selected.
Therefore, even in various wide area wireless networks in which the number of wireless terminals 10 is large and the distance between the low battery terminal N and the bridge terminal M is long, it is possible to increase the operating time of the wireless terminal 10, to equalize the battery remaining time of the plurality of wireless terminals 10, and to reduce the battery replacement cost of the wireless terminal 10.
A third embodiment is an example in which a plurality of wireless terminals 10 are divided into groups and control is performed so as to equalize the battery remaining time of the wireless terminals 10 in the same group.
Therefore, when the wireless terminal 104 belonging to the group G2 is selected as the low battery remaining capacity terminal N, the wireless control device 30 selects the wireless terminal 102 belonging to the same group G2 as the bridge terminal M of the wireless terminal 104. When the wireless terminal 106 belonging to the group G3 is selected as the low battery remaining capacity terminal N, the wireless control device 30 selects the wireless terminal 107 belonging to the same group G3 as the bridge terminal M of the wireless terminal 106.
In the grouping of the wireless terminals 10, one wireless terminal 10 may belong to a plurality of groups. For example, in the example of
Hereinafter, a method of grouping the wireless terminals 10 by the wireless control device 30 in the third embodiment will be described.
For example, the wireless control device 30 may divide the wireless terminals 10 into groups according to the type of the wireless terminal 10, such as an application, an installation company, and the like. In addition, there are cases where the maintenance method differs between the wireless terminals 10 (e.g., the battery replacement timing differs depending on the maintenance company). Therefore, the wireless control device 30 may group the wireless terminals 10 according to the maintenance method of the wireless terminals 10.
Further, when each of the plurality of wireless terminals 10 is a terminal that is fixedly installed and is provided with a position information grasping system such as GPS, the wireless control device 30 may group the wireless terminals 10 using the position information of each of the plurality of wireless terminals 10.
For example, as shown in
Further, from the installation state of
In addition, even if the position information grasping system is not used, when the wireless terminal 10 is installed and the location information of the installed wireless terminal 10 is obtained, the wireless control device 30 may perform grouping using the location information.
As described above, the wireless control device 30 can grasp the wireless terminal 10 capable of short-range wireless connection with the wireless terminal 10 for each of a plurality of wireless terminals 10 without using the position information grasping system. Therefore, the wireless control device 30 may perform grouping using the grasped result.
For example, as shown in
As described above, according to the third embodiment, the wireless control device 30 divides the plurality of wireless terminals 10 into groups, and selects the wireless terminals 10 belonging to the same group as the low battery terminal N as the bridge terminal M of the low battery terminal N. Therefore, it is possible to equalize the battery remaining time of the wireless terminals 10 in the same group and to align the battery replacement timing of the wireless terminals 10 in the same group.
A fourth embodiment is an example in which the future battery driving remaining time of the wireless terminal 10 is predicted, and the low battery terminal N and the bridge terminal M are selected based on the prediction result.
Hereinafter, a method in which the wireless control device 30 selects the low battery terminal N and the bridge terminal M in the fourth embodiment will be described. As the method, for example, the following two methods B1 and B2 can be cited.
(1) Method B1: In the wireless terminal 10, when a component other than the wireless communication circuit 15 (e.g., the sensor 12) uses the same battery 11 as the wireless communication circuit 15, a method of decreasing the remaining battery capacity is changed depending on the usage frequency, usage amount, and the like of the battery 11 by a component other than the wireless communication circuit 15.
Therefore, the wireless control device 30 holds information used for prediction of the battery remaining time in each of a plurality of wireless terminals 10. This information is information obtained from the prediction result of the battery driving remaining time of the wireless terminal 10 predicted in the past, and reflects the usage frequency and usage amount of the battery 11 by components other than the wireless communication circuit 15. This information is, for example, as shown in
In the example of
(2) Method B2: The wireless control device 30 accumulates battery information periodically notified from each of the plurality of wireless terminals 10. Then, for each of the plurality of wireless terminals 10, the wireless control device 30 predicts the battery remaining time of the wireless terminal 10 in the future based on the accumulation result of the battery information periodically collected from the wireless terminal 10, and selects the low battery terminal N and the bridge terminal M based on the prediction result of the battery remaining time.
In the example of
As described above, according to the fourth embodiment, the wireless control device 30 predicts the future battery driving remaining time of each of the plurality of wireless terminals 10, and selects the low battery terminal N and the bridge terminal M based on the prediction result. Therefore, it is possible to select the wireless terminal 10 whose remaining battery time becomes shorter in the future than the other wireless terminal 10 as the low battery terminal N, or to select the wireless terminal 10 whose remaining battery-driven time becomes longer in the future than the other wireless terminal 10 as the bridge terminal M.
Although the invention made by the inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment already described, and it is needless to say that various modifications can be made without departing from the gist thereof.
For example, in the above embodiment, it is assumed that the batteries 11 of the plurality of wireless terminals 10 in the wireless communication system are batteries on the assumption that they are replaced, but the present invention is not limited thereto. The wireless communication system may include a wireless terminal 10 driven by a battery that can be charged at any time by a solar panel or the like, or a wireless terminal 10 driven by a fixed power source from a power outlet. Here, in the wireless terminal 10 driven by a battery that can be charged at any time or a fixed power source, the remaining battery level is not reduced, or the remaining battery level is reduced at a low rate. Therefore, the wireless control device 30 does not select the wireless terminal 10 driven by a battery or a fixed power source that can be charged at any time as the low battery terminal N, but may preferentially select the wireless terminal 10 as the bridge terminal M. When the wireless terminal 10 driven by a battery or a fixed power source that can be charged at any time is preferentially selected as the bridge terminal M, it is possible to increase the operating time of the wireless terminal 10 as a whole system.
In the above embodiment, the wireless control device 30 selects the low battery terminal N and the bridge terminal M based on the calculation result and the prediction result of the battery driving remaining time, but the present invention is not limited thereto. When the wireless controller 30 is connected to the cloud and obtains information from the cloud, such as weather information and traffic information, the wireless controller 30 may select the low battery terminal N and the bridge terminal M in consideration of these information. For example, when the use frequency of the sensor 12 of the wireless terminal 10 increases from weather information, traffic information, or the like (e.g., an increase in the continuation frequency of a rain gauge due to a deterioration in weather, an increase in the measurement frequency of traffic information due to an increase in the traffic volume, or the like) is predicted, it is considered that the power consumption increases, and therefore, the calculation result or the prediction result of the battery driving remaining time may be changed.
Further, in the above embodiment, the wireless terminal 10 selected as the low battery terminal N performs communication with the wireless base station 20 through the short-range wireless communication with the bridge terminal M without performing the wide-area wireless communication thereafter. However, in some wireless communication systems, the wireless terminal 10 cannot be disconnected from the wide area wireless network, and it is necessary to periodically communicate predetermined data with the wide area wireless network. In such a wireless communication system, even in a situation where the wireless terminal 10 selected as the low battery terminal N communicates with the wireless base station through the bridge terminal M, it is necessary to perform communication of predetermined data with the wireless base station 20 through a wide area wireless network, that is, wide area wireless communication.
In this case, the wireless terminal 10 selected as the low battery remaining capacity terminal N communicates predetermined data with the wireless base station 20 through wide area wireless communication at a periodic timing when it is necessary to communicate predetermined data with the wide area wireless network, and communicates with the wireless base station 20 through short-range wireless communication with the bridge terminal M at a timing other than the periodic timing. Further, at this periodic timing, in addition to predetermined data, data to be communicated with the wireless base station 20 through short-range wireless communication with the bridge terminal M may also be communicated with the wireless base station 20 through wide-area wireless communication.
In the above embodiment, the wireless control device 30 is provided independently of the wireless base station 20, but the present invention is not limited thereto. For example, as shown in
In the following embodiments, when it is necessary for convenience, the description will be made by dividing into a plurality of sections or embodiments, but except for the case where it is specifically specified, they are not independent of each other, and one of them is related to some or all of modifications, details, supplementary description, and the like of the other. In the following embodiments, the number of elements or the like (including the number, number, quantity, range, and the like) is not limited to the specific number except the case where it is specified in particular or the case where it is obviously limited to the specific number in principle, and may be a specific number or more or less.
Furthermore, in the following embodiments, it is needless to say that the constituent elements (including element steps and the like) are not necessarily essential except in the case where they are specifically specified and the case where they are considered to be obviously essential in principle. Similarly, in the following embodiments, when referring to the shapes, positional relationships, and the like of components and the like, it is assumed that the shapes and the like are substantially approximate to or similar to the shapes and the like, except for the case in which they are specifically specified and the case in which they are considered to be obvious in principle, and the like. The same applies to the above numerical values and ranges.
The circuit elements constituting the functional blocks of the embodiment are not particularly limited, but are formed on a semiconductor substrate such as a single-crystal silicon substrate by an integrated circuit technique such as a well-known complementary MOS transistor (CMOS).
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same members are denoted by the same reference numerals in principle, and repetitive descriptions thereof are omitted.
(Outline of Signal Processing Device)
The protection target circuit PRC operates based on the clock signal CLK, and includes, for example, a latch circuit LT that performs a latch operation in synchronization with the clock signal CLK, various combination circuits (not shown), and the like. Specifically, the protective circuit PRC is a microcomputer (MCU (Micro Controller Unit)) having a logic circuit and an analogue circuit, a CPU (Central Processing unit), various control logic circuits, or the like.
The delay time detecting circuit DLYDET detects a delay time of signals generated in a predetermined group of circuit elements in the protective circuit PRC. Specifically, the delay time detection circuit DLYDET includes a test circuit element group reflecting the configuration of a predetermined circuit element group in the protection-target circuit PRC, and outputs a delay detection signal Q reflecting the delay time by detecting a delay time of a signal generated in the test circuit element group. The delay amount detection signal Q is, for example, an analog signal having a pulse width reflecting a delay time. Here, at least the protection-target circuit PRC and the delay-time detecting circuit DLYDET are mounted on the same semiconductor chip. The delay detecting circuit DLYDET is provided, for example, inside the protection target circuit PRC or in the vicinity of the protection target circuit PRC.
The clock control circuit CKCTL is provided outside the protection-target circuit PRC, and receives the delay detection signal Q to generate a frequency control signal Vcs for decreasing the frequency of the clock signal CLK in accordance with an increase in the delay time. In this embodiment, the clock-control circuit CKCTL includes a delay-amount-voltage converter circuit DVC and a frequency-control circuit FCTL. The delay amount voltage converter DVC converts the delay amount detection signal Q into a delay amount detection voltage Vcnt having a voltage value corresponding to the pulse width of the delay amount detection signal Q. The frequency control circuit FCTL generates a frequency control signal Vcs for decreasing the frequency of the clock signal CLK in response to an increase in the delay time based on the delay amount detection voltage Vcnt. For example, the frequency control signal Vcs is an analog voltage, and the oscillation circuit VCO is a voltage controlled oscillator.
As described above, the signal processing device SYSa of
The oscillator circuit VCO, the circuit under test DUT, and the clock control circuit CKCTL shown in
(Details of the Delay Time Detection Circuit)
The logic operation circuit EOR performs a logic operation (EXOR operation) using the clock signal CKr and the delayed clock signal CKd input through the buffer BF2 as input, thereby detecting a time difference between the clock signal CKr and the delayed clock signal CKd. Then, as shown in
Here, the delay generation circuit DLYG is composed of a test circuit element group in which the configuration of a predetermined circuit element group in the protection-target circuit PRC is reflected. The inspection circuit element group (predetermined circuit element group in the protection target circuit PRC) is a circuit group in which an increase in delay time due to aging is predicted, and is determined in advance as an observation target by a designer or the like. The test circuit element group is arranged in the protection target circuit PRC or in the vicinity of the protection target circuit PRC so as to faithfully reproduce the degree of deterioration of a predetermined circuit element group in the protection target circuit PRC. Here, as an example, the test circuit element group includes a plurality of stages of inverter circuits IV. However, the test circuit element group is not limited to this, and the test circuit element group may have a configuration in which various logic operation circuits such as inverters, NAND operation circuits, NOR operation circuits, and the like are combined as appropriate and directly connected to each other.
(Details of the Delay Voltage Conversion Circuit)
An input current corresponding to the difference between the voltage of the delay amount detection signal Q and the voltage Vm flows through the input resistor R0. The input current flows through the feedback resistor Rf1 and is accumulated in the feedback capacitor C0. When the steady-state is reached, generally, the average current of the input current flows through the feedback resistor Rf1, and the difference current between the input current and the average current is charged and discharged by the feedback capacitor C0. Therefore, as the duty ratio of the delay amount detection signal Q increases, the mean current increases, and the delay amount detection voltage Vcnt decreases via the feedback resistor Rf1. The level of the mean current and thus the level of the delay detection voltage Vcnt are also controlled by the voltage Vm.
Here, the frequency of the clock signal CLK is controlled so that the frequency of the clock signal CLK is proportional to the magnitude of the delay detecting voltage Vcnt. In the case of
More specifically, the relief margin voltage ΔV is set to a minimum necessary level so that the signal processing device can stably operate even when the protection target circuit PRC has a variation in device temperature, a variation in power supply voltage, a manufacturing variation, and the like. The relief margin voltage ΔV can be adjusted by, for example, the voltage Vm from the variable voltage source VGm in
Further, the delay amount voltage conversion circuit DVC may have any function as long as it has a function of converting the magnitude of the pulse width of the delay amount detection signal Q into a DC voltage value, and is not particularly limited to the configuration example of
(Details of the Frequency Control Circuit)
The level shift circuit LS is, for example, a differential amplifier including resistors R3 to R5, a feedback resistor R6, an operational amplifier AMP3, and a variable voltage source VGr. The operational amplifiers AMP3 are supplied with power supply voltages ΔVDD. The variable voltage source VGr generates a voltage Vcoref reference on the ground power supply voltage GND. The level shifting circuit LS adjusts the bias level of the output voltage G×Vcnt of the gain adjusting circuit VGA to generate the frequency control signal Vcs. Specifically, for example, when the resistors R3 to R6 are set to the same resistance values, the differential amplifier outputs “Vcoref−(G×Vcnt)”. That is, the differential amplifiers invert the output voltage (G×Vcnt) of the gain adjuster VGA and level-shift the inverted output voltage by the voltage Vcoref to generate the frequency control signal Vcs. The variable voltage source VGr may be a fixed voltage source in which an optimum output voltage is set in advance.
The frequency control circuit FCTL is not limited to the configuration of
(Details of the Oscillator Circuit)
The capacitance value of the variable capacitor Cv is controlled by the frequency control signal Vcs. As a result, the delay time of the signal inputted from the inverter circuit IV3 of the last stage to the inverter circuit IV1 of the first stage changes, and the frequency of the clock signal CLK can be changed. Specifically, for example, when the delay time detected by the delay time detecting circuit DLYDET increases, the voltage level of the frequency control signal Vcs decreases. In response to this, the capacitance of the variable capacitance Cv increases, and the delay time of the signal transmitted from the inverter circuit IV3 to the inverter circuit IV1 increases, so that the frequency of the clock signal CLK decreases.
On the other hand, the oscillator VCOb shown in
That is, when the deterioration delay time detected by the protected circuit PRC increases from “td0” to “td1”, the voltage level of the frequency control signal Vcs decreases from “V11” to “V10”. As a result, as shown in
As described above, when the signal processing device according to the first embodiment is used, the frequency fclk of the clock signal CLK can be automatically decreased in accordance with an increase in the delay time detected by the protection target circuit PRC. As a result, in the protection target circuit PRC, even when the delay time increases with the aging deterioration, in other words, when the delay failure occurs, it is possible to prevent the malfunction.
In the product of
(Modifications of the Signal Processing Device)
As described above, although the signal processing device SYSa of
When such digital circuits are used, for example, the relationship between the deterioration delay times and the frequency fclk of the clock signal CLK shown in
(Control Flow of Signal Processing Device)
In operation S3, the delay amount voltage converter DVC converts the delay amount detection signal Q into a delay amount detection voltage Vcnt having a voltage value corresponding to the pulse width D of the delay amount detection signal Q. Thereafter, the clock control circuit CKCTL generates a frequency control signal Vcs for decreasing the frequency of the clock signal CLK in accordance with the increase in the delay time based on the detection delay voltage Vcnt in operation S4.
(Outline of the Signal Processing Device (Comparative Example))
As described above, if the failure detecting unit ERRDU is provided in the signal-processing-device SYS′a, the aging deterioration can be detected. However, simply providing the failure detecting unit ERRDU in the device does not necessarily prevent malfunction of the device and secure safety. That is, as described above, it is necessary to take other measures such as duplexing the device and requesting the user to replace the components at an early stage in response to the detection of aging deterioration. As a result, there arise problems such as an increase in cost and shortening of product life due to ensure an excessive margin. Further, in the case of component replacement, it is not always possible to prevent malfunction of the device until replacement is performed, and it is not always possible to secure safety or the like.
For example, by using such a signal processing device, the same control as that of the signal processing device SYSa of the first embodiment can be performed. However, in the method as shown in
Further, in the method as shown in
On the other hand, in the method of the first embodiment, the delay time detection circuit DLYDET outputs a signal representing the ratio of the pulse width (time difference) D to the cycle T of the clock signal CLK as the delay amount detection signal Q, as shown in
As a specific operation example, for example, as shown in
Thereafter, an operation is repeated in which the delay amount voltage conversion circuit DVC lowers the delay amount detection voltage Vcnt in accordance with the shortening of the period T, the frequency control circuit FCTL extends the period T in response thereto, the delay amount voltage conversion circuit DVC raises the delay amount detection voltage Vcnt in response thereto, and the frequency control circuit FCTL shortens the period T in response thereto. At this time, if the gain of the delay amount voltage converter circuit DVC and the gain G of the frequency control circuit FCTL are appropriately determined, the amounts of change in the delay amount detected voltage Vcnt and the period T are successively reduced in the repetitive process, and the period T (frequency) of the clock signal CLK can be converged to predetermined values.
(Comparison of Product Lifetime Between the Method of Embodiment 1 and the Method of the First Comparative Example)
The lower frame of
The lower frame of
When the delay time td reaches the first reference value D1, the signal-processing-device SYSa lowers the frequency fclk to a second frequency fclk[2] lower than the first frequency fclk[1]. Thereafter, when the delay time td reaches the second reference amount d2 which is larger than the first reference amount d1, the signal-processing-device SYSa lowers the frequency fclk to the third frequency fclk[3] which is lower than the second frequency fclk[2]. Thereafter, in the same manner, the automatic frequency adjustment is performed toward the lower limit frequency at which the reduction of the processing capacity is allowed, and the automatic frequency adjustment is finished when the relief margin ΔT2 is added to the lower limit frequency.
Here, for example, when the protection target circuit RPC operates at the second frequency fclk [2], even if the delay time td between the reference amounts d1 to d2 occurs, the malfunction of the protection target circuit RPC does not occur. That is, the reference amounts d1 and d2 are preset to values having a minimum margin with respect to the delay time td which causes a malfunction when the protected circuit RPC is operated at the second frequency fclk [2].
For example, if the delay time immediately after the start of use in the protective circuit RPC is “td[0]” and the time of 1% of the cycle T of the clock signal CLK corresponding to the first frequency fclk[1] is “Δtc[1]”, the reference quantity d1 is determined to be, for example, “td[0]+Δtc[1]” or the like. Similarly, when the period T of the clock signal CLK corresponding to the second frequency fclk[2] is 1% of the period T of the clock signal CLK, the reference quantity d2 is determined to be, for example, “d1+Δtc[2]” or the like. In this case, the relief margin ΔT2 in
The reference amounts d1 and d2 may be determined to be 10% of the time instead of 1% of the time of the cycle T of the clock signal CLK. In this case, although the margin for the malfunction is small, the protection target circuit RPC can be operated at a higher frequency, and thus, a decrease in the processing capacity can be suppressed. In addition, the frequency of switching the frequency of the clock signal CLK can be reduced, and the operation of the signal processing device can be stabilized.
(Effects of Embodiment 1)
As described above, by using the signal processing device of the first embodiment, it is possible to prevent a malfunction, typically, even when a delay failure due to aging occurs. In addition, when the signal processing device is applied to a device requiring safety such as an automobile or the like, it is possible to maintain safety substantially equivalent to that at the time of normal operation. That is, although the processing capability is lowered by lowering the frequency fclk of the clock signal CLK, it is possible to prevent malfunctions such as operation errors and logical runaway and to maintain security within a range in which the processing capability is allowed to be lowered. Further, as described in
Further, in another aspect, as described in
Although the increase of the delay time with the aging has been described as a problem here, the increase of the delay time can also be caused by variations of various environmental parameters such as, for example, the power supply voltage and the ambient temperature. For example, if the power supply voltage varies, ±10% of the rated voltage, and if the ambient temperature Ta varies, Ta varies from −40° C. to 125° C. At the stage of device design and circuit design, it is usually necessary to take such variations into consideration to ensure a sufficient safety margin.
On the other hand, when the signal processing device of the first embodiment is used, even when the delay time is increased due to such a variation in the environmental parameter, the delay time can be reduced by decreasing the frequency fclk of the clock signal CLK. As a result, the safety margin required at the stage of device design and circuit design can be relaxed, and the design can be facilitated accordingly. Further, since the safety margin can be relaxed not only in the design stage but also in the manufacturing stage, the production yield of the signal processing device can be improved.
(Operation of the Signal Processing Device (Embodiment 2))
That is, the frequency fclk of the clock signal CLK is set to a prescribed frequency f1 (fspec) based on the specifications of the product in the normal area of
(Outline of the Signal Processing Device (Embodiment 3))
Specifically, the deterioration detecting signals INT are generated in the deterioration relieving area (the area of the deterioration delay time td0˜td1) shown in
(Details of the Deterioration Determination Circuit)
The warning circuit ARM shown in
(Control Flow of Signal Processing Device (Embodiment 3))
(Configuration of Vehicle Control Device)
The signal-processing device SYSb of
(Effects of Embodiment 3)
As described above, by using the signal processing device of Embodiment 3, in addition to the various effects described in Embodiments 1 and 2, it is possible to inform the host device and the user that the signal processing device is extending the life beyond the normal life. As a result, the host device can prevent the entire device from malfunctioning and enhance safety by, for example, performing an adjustment with another device. In addition, since the safety of the protection target circuit PRC is secured to some extent by the above-described deterioration relief, the user can request the replacement of parts or the like with sufficient time even when receiving the warning signal. Such an effect is particularly advantageous in the vehicle control device VHC as shown in
(Outline of the Signal Processing Device (Embodiment 4))
The semiconductor device DEVa includes an external terminal PN1 to which the clock signal CLK is inputted and an external terminal PN2 to which the delay detecting signal Q is outputted. The semiconductor device DEVb includes an external terminal PN3 for outputting the clock signal CLK to the external terminal PN1 of the semiconductor device DEVa, and an external terminal PN4 for receiving the delay detecting signal Q from the external terminal PN2 of the semiconductor device DEVa.
(Effects of Embodiment 4)
As described above, when the signal processing device of Embodiment 4 is used, in addition to the various effects described in Embodiments 1 to 3 being obtained, it is possible to effectively utilize the existing apparatus to improve the versatility of the device. That is, the semiconductor device DEVa may be any of various conventional semiconductor devices as long as the semiconductor device has the same function as that of the delay detecting circuit DLYDET. By adding the semiconductor device DEVb to the conventional semiconductor device, various methods described in Embodiments 1 to 3 can be realized.
Although the invention made by the present inventor has been specifically described based on the embodiment, the present invention is not limited to the embodiment described above, and various modifications can be made without departing from the gist thereof. For example, the above-described embodiments have been described in detail in order to easily understand the present invention, and are not necessarily limited to those having all the configurations described. In addition, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. It is also possible to add, delete, or replace some of the configurations of the respective embodiments.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2019-039227 | Mar 2019 | JP | national |
