Patent Publication Number: US-2022240177-A1

Title: Method of setting reception period of repeater, communication system, and repeater

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims priority from Japanese Patent Application, Tokugan, No. 2021-009662 filed on Jan. 25, 2021, the content of which is hereby incorporated by reference into this application. 
     FIELD OF THE INVENTION 
     The present disclosure relates to technology of setting the reception period of a repeater for receiving radio waves from a transmitter. 
     BACKGROUND OF THE INVENTION 
     Communication systems have been known that include a transmitter and a repeater for receiving radio waves from a transmitter. For instance, Japanese Unexamined Patent Application Publication, Tokukai, No. 2018-152047 discloses a sensor device. The sensor device of Japanese Unexamined Patent Application Publication, Tokukai, No. 2018-152047 includes: a sensor unit for detecting environmental information; a sensor device communication unit for transmitting the detected environmental information to another sensor device; a primary battery for supplying electric power to the sensor unit and the sensor device communication unit; and a sensor-device coupler section for detachably attaching an auxiliary battery for supplying electric power to the sensor device. When there is no auxiliary battery attached to the sensor device, the sensor device operates on the primary battery; when there is an auxiliary battery attached, the sensor device operates on either the primary battery or the auxiliary battery. The sensor device communication unit is capable of further transmitting information on the battery voltage or information on the auxiliary battery voltage to another sensor device. 
     Japanese Unexamined Patent Application Publication, Tokukai, No. 2011-13765 discloses a sensor network system. The sensor network system of Japanese Unexamined Patent Application Publication, Tokukai, No. 2011-13765 includes: sensor network terminals having a wireless communication function and individually driven by an environmental generator; and a system manager connected to any of the sensor network terminals via a wired link. Each sensor network terminal includes: means for detecting the amount of power generated by the environmental generator connected to the sensor network terminal and further detecting the charged capacity of the environmental generator; means for transmitting the detected amount of power generated and the detected charged capacity to the system manager; and means for changing a measurement period setting on the basis of a measurement period transmitted from the system manager. The system manager includes: means for computing a measurement period of the sensor network terminal on the basis of an amount of power generated and a charged capacity both obtained from the sensor network terminal; and means for transmitting results of the computation as value settings to the sensor network terminal. 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     The present disclosure has an object to provide technology of more efficiently setting the reception period of a repeater or the transmission period of a transmitter. 
     Solution to the Problems 
     The present disclosure, in an aspect thereof, provides a method of setting the reception period of a repeater that includes a battery and that receives radio waves transmitted by one or more transmitters, thereby setting the reception period of the repeater on the basis of the power consumption Pk (Wh) of the one or more transmitters and the power consumption Pc (Wh) of the repeater. 
     Advantageous Effects of the Invention 
     As described in the foregoing, the present disclosure enables setting the reception period of a repeater or the transmission period of a transmitter. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram of an entire communication system  1  including one repeater  100  and one transmitter  200  in accordance with a first embodiment. 
         FIG. 2  is a block diagram of the entire communication system  1  including one repeater  100  and a plurality of transmitters  200  in accordance with the first embodiment. 
         FIG. 3  is a block diagram of a structure of the repeater  100  in accordance with the first embodiment. 
         FIG. 4  is a diagram depicting a transmission period and a reception period in accordance with the first embodiment. 
         FIG. 5  is a graph representing the power consumption of each device and the total power consumption in accordance with the first embodiment. 
         FIG. 6  is a flow chart representing a process performed by the repeater  100  in accordance with the first embodiment. 
         FIG. 7  is a block diagram of a structure of a repeater  100  in accordance with a second embodiment. 
         FIG. 8  is a flow chart representing a process performed by the repeater  100  in accordance with the second embodiment. 
         FIG. 9  is a graph representing a correlation between objective functions f(x) and g(x) in accordance with a third embodiment. 
         FIG. 10  is a flow chart representing a process performed by a repeater  100  in accordance with the third embodiment. 
         FIG. 11  is a flow chart representing a process performed by a repeater  100  in accordance with a fourth embodiment 
         FIG. 12  is a table of various parameters of a repeater  100  and a transmitter  200  in accordance with a fifth embodiment. 
         FIG. 13  is a table representing a correlation between the transmission period and the power consumption of the transmitter  200  for different reception periods of the repeater  100  in a communication system  1  including one repeater  100  and one transmitter  200  in accordance with the fifth embodiment. 
         FIG. 14  is a table representing a preferable correlation between the reception period of the repeater  100  and the transmission period of the transmitter  200  in the communication system  1  including one repeater  100  and one transmitter  200  in accordance with the fifth embodiment. 
         FIG. 15  is a table representing a correlation between the transmission period and the power consumption of each transmitter  200  for different reception periods of the repeater  100  in a communication system  1  including one repeater  100  and a plurality of transmitters  200  in accordance with the fifth embodiment. 
         FIG. 16  is a table representing a preferable correlation between the reception period of the repeater  100  and the transmission period of each transmitter  200  in the communication system  1  including one repeater  100  and a plurality of transmitters  200  in accordance with the fifth embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The following will describe an embodiment of the present disclosure with reference to drawings. Identical members are denoted by the same reference numerals throughout the following description. Such members are given the same names and have the same functionality, and description thereof is therefore not repeated. 
     First Embodiment 
     Overall Structure of Communication System  1   
     A description is given first of an overall structure of a communication system  1  in accordance with the present embodiment. The communication system  1  may, for example, include either one transmitter  200  for each repeater  100  as shown in  FIG. 1  or a plurality of transmitters  200  for each repeater  100  as shown in  FIG. 2 . The transmitter or transmitters  200  transmit(s) data including various information from a wireless antenna, so that the repeater  100  can receive and store the data and transmit the data to, for example, another like device or a server. 
     Structure of Repeater  100   
     A description is given next of a structure of the repeater  100 . Referring to, for example,  FIG. 3 , the repeater  100  includes a control unit  110 , a battery  120 , an electric power adjustment unit  121 , a detection unit  150 , and a reception unit  160  that is built, for example, around a wireless communication antenna. 
     The control unit  110  drives the reception unit  160  on the electric power provided by the battery  120 . The control unit  110  receives data from the transmitter  200  via the reception unit  160 , for example, to store the data in a memory in the control unit  110  and transmit the data to another device such as a server. 
     In the present embodiment, the control unit  110 , for example, activates the reception unit  160  once every reception period Tc to receive data and deactivates the reception unit  160  when a reception time tc elapses, by using the detection unit  150 , as shown in  FIG. 4 . 
     Particularly in the present embodiment, the control unit  110  is configured to reduce either the power consumption of the repeater  100  or the power consumption of the transmitter  200  or the sum of both by the control method described in the following. 
     Structure of Transmitter  200   
     The transmitter  200  has the same structure as the repeater  100 , and description thereof is not repeated in this embodiment. For instance, the transmitter  200  includes a control unit  110  that, for example, activates the reception unit  160  once every transmission period Tk to transmit data and deactivates the reception unit  160  when a transmission time tk elapses, by using the detection unit  150 , as shown in  FIG. 4 . 
     Method of Determining Reception Period for Repeater  100   
     A description is given now of method of determining a reception period for the repeater  100  in accordance with the present embodiment. First, the following are formulas from which the power consumption of the transmitter  200  and the power consumption of the repeater  100  are derived respectively. 
         Pk={Qk Tk +( Rk−Qk )* tk{* 3600/ Tk ]  (1)
 
     Pk: power consumption of transmitter (Wh) 
     Qk: standby power consumption (constant) 
     Rk: transmission power consumption (constant) 
     tk: transmission time (sec.) 
     Tk: transmission period (sec.) 
         Pc ={( Rc−Qc )* Tk+Qc Tc}* 3600/ Tc    (2)
 
     Pc: power consumption of repeater (Wh) 
     Qc: standby power consumption (constant) 
     Rc: reception power consumption (constant) 
     tc (Tk): reception time (period of transmitter) (sec.) 
     Tc: reception period (sec.) 
       FIG. 5  is a graph obtained by plugging in the actual reception and standby power consumptions of the repeater  100  and the actual transmission and standby power consumptions of the transmitter  200 . More particularly,  FIG. 5  is a graph prepared by plugging the actual reception and standby power consumptions of the repeater  100  and the actual transmission and standby power consumptions of the transmitter  200  into formulas (1) and (2) respectively under the following conditions: 
     The transmission time of the transmitter is fixed to 1 second; 
     The transmission period of the transmitter is varied in the range of 1 second to 200 seconds; 
     The reception period of the repeater is fixed to 600 seconds (10 minutes); 
         Qk= 0.1 ( W ); 
         Rk= 0.4 ( W ); 
         Qc= 0.000021 ( W ); and 
         Rc= 0.557 ( W ). 
     In  FIG. 5 , the solid line indicates the power consumption of the transmitter  200 , the dotted line indicates the power consumption of the repeater  100 , and the dash-dot line indicates the total power consumption of the repeater  100  and the transmitter  200 . 
     This graph shows that: 
     (1) The power consumption of the transmitter  200 , the power consumption of the repeater  100 , and the total power consumption change with the transmission period of the transmitter  200 ; 
     (2) The power consumptions decrease with an increase in the transmission period; 
     (3) In the repeater, the power consumption increases with an increase in the transmission period. The power consumption of the repeater is approximately 55 times smaller in the neighborhood of the minimum point than when the repeater is constantly on standby for reception; 
     (4) From these phenomena, the total power consumption will be significantly reduced by reducing the reception time of the repeater and increasing the transmission period of the transmitter; and 
     (5) In the present embodiment, the total power consumption of the transmitter  200  and the repeater  100  takes a minimum value when the transmitter has a transmission period of approximately 11 seconds. 
     When there is provided a plurality of transmitters  200 , the repeater  100  requires a minimum reception time that is equal to the sum of the transmission periods of the transmitters  200 , and the repeater  100  has an optimal reception time that is equal to the sum of the optimal reception times of the transmitters  200 . 
     The description so far demonstrates that the minimum value of the total power consumption under current conditions can be calculated by calculating, for example, the power consumption of the repeater  100  for the reception period thereof under current conditions and the power consumption of the transmitter  200  for the transmission period thereof under current conditions. 
     Process of Setting Reception Period of Repeater  100   
     A description is given next of the information processing performed by the control unit  110  in the repeater  100  in accordance with the present embodiment with reference to  FIG. 6 . First, the control unit  110 , for example, retrieves or acquires the current reception period Tc and the current reception time to from the memory or the detection unit  150  (step S 112 ). The control unit  110 , for example, further retrieves or acquires the standby power consumption Rc and the reception standby power consumption Qc of the battery  120  from the memory or the electric power adjustment unit  121  (step S 112 ). 
     The control unit  110  then calculates the power consumption Pc (Wh) of the repeater from formula (2) as described earlier (step S 114 ). 
     The control unit  110 , for example, retrieves or acquires the transmission period Tk and the reception time tk of the transmitter  200  from the memory or the transmitter  200  via or not via the reception unit  160  (step S 122 ). The control unit  110 , for example, further retrieves or acquires the standby power consumption Rc and the reception standby power consumption Qc of the battery  120  from the memory or the electric power adjustment unit  121  (step S 122 ). 
     The control unit  110  then calculates the power consumption Pk (Wh) of the transmitter from formula (1) as described earlier (step S 124 ). 
     The control unit  110  calculates the total power consumption ΣP=Pk+Pc (step S 130 ). 
     The control unit  110  determines whether or not the total power consumption is low under current conditions on the basis of the graph in  FIG. 5  under current conditions (step S 132 ). 
     If the total power consumption is relatively low under current conditions (YES in step S 132 ), the control unit  110  changes no parameters, that is, continues the current operation (step S 134 ). 
     If the total power consumption is relatively high under current conditions (NO in step S 132 ), the control unit  110  changes for example, the reception period and the reception time in such a manner as to reduce the total power consumption (step S 136 ). The control unit  110  repeats these steps to adjust the reception period of the repeater  100  to an optimal value. 
     Second Embodiment 
     The repeater  100  includes the battery  120  in the foregoing embodiment. In the present embodiment, the repeater  100  includes an environmental generation unit  225 . 
     More particularly, referring to  FIG. 7 , the repeater  100  includes a control unit  110 , a storage battery  220 , an electric power adjustment unit  121 , a second detection unit  222 , a detection unit  150 , and a reception unit  160 . 
     The environmental generation unit  225  may be an environmental generator, such as a solar cell, a piezoelectric generator, or a thermal power generator, that generates and stores electric power in the storage battery  220 . The second detection unit  222  measures the amount of the power generated by the environmental generation unit  225 . The control unit  110 , for example, drives the reception unit  160  and sets the reception period of the reception unit  160  on the electric power provided by the storage battery  220 . 
     A description is given now of the information processing performed by the control unit  110  in the repeater  100  in accordance with the present embodiment with reference to  FIG. 8 . Steps S 112 , S 114 , S 122 , S 124 , and S 130  here are the same as those in the foregoing embodiment, and description thereof is not repeated. 
     The control unit  110  acquires the amount E of power generated by the environmental generation unit  225  from the second detection unit  222  (step S 240 ). 
     The control unit  110  determines whether or not the amount E is larger than the total power consumption ΣP=Pk+Pc (step S 232 ). 
     If the amount E is larger than the total power consumption under current conditions (YES in step S 232 ), the control unit  110  changes no parameters, that is, continues the current operation (step S 134 ). 
     If the total power consumption is larger than the amount of power generated under current conditions (NO in step S 232 ), the control unit  110  changes, for example, the reception period and the reception time in such a manner as to reduce the total power consumption (step S 136 ). The control unit  110  repeats these steps to maintain the total power consumption equal to or below the amount of power generated. 
     Third Embodiment 
     The control unit  110  may perform multi-objective optimization to optimize the reception period. Formulas (1) and (2) described above are used again in the present embodiment. The same conditions as those in the foregoing embodiments are used as given below: 
         Qk= 0.1 ( W ); 
         Rk= 0.4 ( W ); 
         Qc= 0.000021 ( W ); and 
         Rc= 0.557 ( W ) 
     These conditions are plugged into formulas (1) and (2). 
         Pk= 1080* tk/Tk+ 360 
         Pc= 2005.2* Tk/Tc+ 0.0756 
     Multi-objective optimization that involves three variables and two objectives is performed on these two formulas as follows. The constraint functions may naturally vary with the operating environment of the repeater  100  and the transmitter  200 . 
       X=Tk; 
       Y=tk; 
       Z=Tc; 
       Pk+Pc is minimized; 
         Pk= 1080* Y/X+ 360; 
         Pc= 2005.2* X/Z+ 0.0756; 
       Tc&gt;Tk&gt;tk&gt;0; and 
       Objective functions are  f ( x )= Pk= 1080* Y/X+ 360 and  g ( x )= Pc= 2005.2* X/Z+ 0.0756 
     Optimization is Done by NSGA-2 in the Present Embodiment 
       FIG. 9  shows results of the multi-objective optimization in accordance with the present embodiment. 
     X=Tk, Y=tk, and Z=Tc are thus determined that reduces the sum of the objective functions f(x) and g(x), that is, the total power consumption, under current conditions. 
     A description is given of the information processing performed by the control unit  110  in the repeater  100  in accordance with the present embodiment with reference to  FIG. 10 . Steps S 112 , S 114 , S 122 , and S 124  here are the same as those in the foregoing embodiments, and description thereof is not repeated. 
     The control unit  110  generates objective functions f(x)=Pk and g(x)=Pc under current conditions to perform multi-objective optimization (step S 330 ). 
     The control unit  110  determines the reception period Tc of the repeater  100  on the basis of the results of the optimization to set the reception period Tc again (step S 332 ). 
     Fourth Embodiment 
     In the foregoing embodiments, the reception period of the repeater  100  is determined based not only on the parameters of the repeater  100 , but also on, for example, the transmission period  717 k and the reception time tk of the transmitter  200 . In contrast, the reception period of the repeater  100  is determined based primarily on the parameters of the repeater  100  in the present embodiment. 
     A description is given of the information processing performed by the control unit  110  in the repeater  100  in accordance with the present embodiment with reference to  FIG. 11 . First, the control unit  110 , for example, retrieves or acquires the current reception period Tc and the current reception time tc from the memory or the detection unit  150  (step S 112 ). The control unit  110 , for example, further retrieves or acquires the standby power consumption Re and the reception standby power consumption Qc of the battery  120  from the memory or the electric power adjustment unit  121  (step S 112 ). 
     The control unit  110  then calculates the power consumption Pk (Wh) of the transmitter from formula (1) as described earlier (step S 114 ). 
     The control unit  110  acquires the amount E of power generated by the environmental generation unit  225  from the second detection unit  222  (step S 240 ). 
     The control unit  110  determines whether or not the amount E is larger than the power consumption Pc of the repeater  100  (step S 232 ). 
     If the amount E is larger than the power consumption Pc of the repeater  100  under current conditions (YES in step S 232 ), the control unit  110  changes no parameters, that is, continues the current operation (step S 134 ). 
     If the power consumption Pc of the repeater  100  is larger than the amount E of power generated under current conditions (NO in step S 232 ), the control unit  110  changes, for example, the reception period and the reception time in such a manner as to educe the power consumption of the repeater  100  (step S 136 ). The control unit  110  repeats these steps to maintain the total power consumption equal to or below the amount of power generated. 
     Fifth Embodiment 
     A description is given of a configuration for setting the transmission period of the transmitter  200 , first, in a communication system  1  including one repeater  100  and one transmitter  200 . 
     The minimum value of the power consumption of the transmitter  200 , the minimum value of the power consumption of the repeater  100 , the maximum value of the power consumption of the transmitter  200 , and the maximum value of the power consumption of the repeater  100  are calculated, as shown in  FIG. 12 . 
     Using these values, the optimal reception time that minimizes the total power consumption of the transmitter  200  and the repeater  100 , this minimum total power consumption, the optimal reception time that maximizes the total power consumption of the transmitter  200  and the repeater  100 , and this maximum total power consumption are calculated for different reception periods of the repeater  100 .  FIG. 13  shows results of the calculation. 
       FIG. 13  demonstrates that there is a correlation between the reception period of the repeater  100  and the reception period of the transmitter  200  in the system including one repeater  100  and one transmitter  200 . Referring to  FIG. 14 , (a) the transmission period of the transmitter is preferably set to from 3.3 seconds to 700 seconds, both inclusive, when the reception period of the repeater is from 8 hours inclusive to 24 hours exclusive; (b) the transmission period of the transmitter is preferably set to from 2.0 seconds to 400 seconds, both inclusive, when the reception period of the repeater is from 3 hours inclusive to 8 hours exclusive; (c) the transmission period of the transmitter is preferably set to from 1.0 seconds to 250 seconds, both inclusive, when the reception period of the repeater is from 1 hour inclusive to 3 hours exclusive; and (d) the transmission period of the transmitter is preferably set to from 0.02 seconds to 150 seconds, both inclusive, when the reception period of the repeater is from 1 second inclusive to 1 hour exclusive. 
     A description is given of a configuration for setting the transmission period of the transmitter  200 , next, in a communication system  1  including one repeater  100  and ten transmitters  200 . 
     The minimum value of the power consumption of the transmitter  200 , the minimum value of the power consumption of the repeater  100 , the maximum value of the power consumption of the transmitter  200 , and the maximum value of the power consumption of the repeater  100  are calculated as shown in  FIG. 14 . 
     Using these values, the optimal reception time that minimizes the total power consumption of the transmitter  200  and the repeater  100 , this minimum total power consumption, the optimal reception time that maximizes the total power consumption of the transmitter  200  and the repeater  100 , and this maximum total power consumption are calculated for different reception periods of the repeater  100 .  FIG. 15  shows results of the calculation. 
       FIG. 15  demonstrates that there is a correlation between the reception period of the repeater  100  and the reception periods of the transmitters  200  in the system including one repeater  100  and ten transmitters  200 . Referring to  FIG. 17 , (a) the transmission period of each transmitter is preferably set to from 33 seconds to 7,000 seconds, both inclusive, when the reception period of the repeater is from 8 hours inclusive to 24 hours exclusive; (b) the transmission period of each transmitter is preferably set to from 20 seconds to 4,000 seconds, both inclusive, when the reception period of the repeater is from 3 hours inclusive to 8 hours exclusive; (c) the transmission period of each transmitter is preferably set to from 10 seconds to 2,500 seconds, both inclusive, when the reception period of the repeater is from 1 hour inclusive to 3 hours exclusive; and (d) the transmission period of each transmitter is preferably set to from 0.2 seconds to 1,500 seconds, both inclusive, when the reception period of the repeater is from 1 second inclusive to 1 hour exclusive. 
       FIG. 16  demonstrates that there would be a correlation between the reception period of the repeater  100  and the reception periods of the transmitters  200  in the system including one repeater  100  and n transmitters  200 : (a) the transmission period of each transmitter is preferably set to from 3.3×n seconds to 700×n seconds, both inclusive, when the reception period of the repeater is from 8 hours inclusive to 24 hours exclusive; (b) the transmission period of each transmitter is preferably set to from 2.0×n seconds to 400×n seconds, both inclusive, when the reception period of the repeater is from 3 hours inclusive to 8 hours exclusive; (c) the transmission period of each transmitter is preferably set to from 1.0×n seconds to 250×n seconds, both inclusive, when the reception period of the repeater is from 1 hour inclusive to 3 hours exclusive; and (d) the transmission period of each transmitter is preferably set to from 0.02×n seconds to 150×n seconds, both inclusive, when the reception period of the repeater is from 1 second inclusive to 1 hour exclusive. 
     The transmission period of the transmitter  200  may be set to the optimal value on the basis of these criteria by a worker acquiring the parameters related to the repeater  100  and the transmitter  200 . Alternatively, the transmission period of the transmitter  200  may be automatically set to a value that suits the reception period of the repeater  100  by a control unit, for the transmitter  200 , for example, receiving the reception period from the repeater  100  through a wireless communication antenna or receiving an input through an operation unit on how many transmitters  200  are provided for each repeater  100 . 
     The embodiments disclosed herein are for illustrative purposes only in every respect and provide no basis for restrictive interpretations. The scope of the present disclosure is defined only by the claims and never bound by the foregoing description. Those modifications and variations that may lead to equivalents of claimed elements are all included within the scope of the disclosure.