JP5852552B2 - Access point device, access point device control method, and wireless communication system - Google Patents

Description

  The present invention relates to an access point device for saving power in a wireless communication system in which a plurality of access point devices communicate in a mesh configuration, a control method for the access point device, and a wireless communication system.

  In recent years, a wireless local area network (LAN) has become widespread in homes and offices, and wireless LAN terminals are installed in many information devices and widely used as a means of Internet access. A commonly used wireless LAN is standardized as the IEEE 802.11 standard.

  A case will be described in which a wireless LAN access point device (hereinafter referred to as an access point) operates with a power source using a storage battery and natural energy. Here, a natural energy generator represented by a solar power generator is mainly assumed as a power source, but the natural energy is not limited to sunlight. For example, in the case of wind power, the solar power generator is treated as a wind power generator, and the amount of solar radiation is treated as the air volume. The access point generates power with a solar power generator and operates using the generated power. In addition, surplus power out of the power generated by the solar power generator is stored in a storage battery and used at night or in bad weather. In such an access point that operates with a solar power generator and a storage battery, it is required to suppress the size of the solar power generator and the storage battery for the purpose of cost reduction and miniaturization. However, when a large amount of restraint is imposed on the solar power generator or the storage battery, the system may not operate depending on the power consumption of the access point. For this reason, there is a demand for power saving of access points, and studies are being made to save power in communication with wireless LAN terminals (hereinafter referred to as wireless terminals) (see Non-Patent Document 1).

  Hereinafter, it is assumed that there are a plurality of access points, each access point communicates with a terminal in the infrastructure mode, and communication between each access point is performed in a mesh configuration. The IEEE802.11s standard can be used for communication performed in a mesh configuration. The IEEE 802.11s standard standardizes a communication protocol performed by a plurality of wireless LAN devices (access points) in a mesh configuration.

  In IEEE802.11s, operation in Active mode / Light Sleep mode / Deep Sleep mode is defined as a power saving function for communication between wireless LAN devices. In the Active mode, only the Awake state in which frames can be transmitted and received is always taken. In the Light Sleep mode / Deep Sleep mode, the Awake state and the Doze state can be taken. In the Doze state, all of transmission, reception, and listening cannot be performed by cutting off power supply to some circuits, but power consumption can be reduced compared to the Awake state (see Non-Patent Document 2).

  In IEEE 802.11s, a wireless LAN device constructs a peer with each of a plurality of adjacent wireless LAN devices. For each peer, an operation mode of Active mode / Light Sleep mode / Deep Sleep mode is selected. Here, a peer is a communication path between wireless LAN devices. Each mode can be switched at an arbitrary timing, but the standard for determining the switching is not defined in the standard.

  In the Active mode, since the wireless LAN device is always in an Awake state, a frame transmitted from the wireless LAN device corresponding to the peer can be received at an arbitrary timing, and the wireless LAN device corresponding to the peer can be received. Frames can be transmitted at any timing. For this reason, the power supply to the circuit is not cut even during the standby time, and the power consumption increases.

  In the Light Sleep mode, the wireless LAN device uses both the Awake state and the Doze state. Although the frame cannot be transmitted / received in the Doze state, it operates in the Awake state for a certain time after the transmission of the beacon signal, and during that period, the frame is transmitted / received according to a predetermined procedure. Further, in order to always receive a beacon signal transmitted by a peer wireless LAN device, the state always transits to the awake state at the same timing. After receiving the beacon signal, the frame can be transmitted / received to / from the peer wireless LAN device according to the information described in the beacon signal. After frame transmission / reception is completed, power saving can be achieved by transitioning to the Doze state.

  Even in the Deep Sleep mode, the wireless LAN device uses both the Awake state and the Doze state. Although the frame cannot be transmitted / received in the Doze state, it operates in the Awake state for a certain time after the transmission of the beacon signal, and during that period, the frame is transmitted / received according to a predetermined procedure. In the Deep Sleep mode, it is not always necessary to receive a beacon signal transmitted by a peer wireless LAN device. Therefore, since it is not necessary to transit to the Awake state at the timing when the beacon signal is transmitted, it is possible to operate in the Doze state for a longer time compared to the Light Sleep mode, and further power saving can be achieved.

Resource Allocation and Outage Control for Solar-Powered WLAN Mesh Networks, IEEE Transactions on Mobile Computing, Vol.6, No.8, August 2007. Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications Amendment 10: Mesh Networking, IEEE Std. 802.11s-2011, September 2011.

  FIG. 6 is a schematic block diagram illustrating a configuration example of a wireless communication system including an access point that performs communication in a mesh configuration. As shown in the figure, there are three access points 91, 92, and 93, and the access points 91, 92, and 93 are connected to each other in a mesh configuration by wireless communication. A wireless terminal 94 is connected to the access point 91 in the infrastructure mode.

  Further, the solar power generator 21 and the storage battery 22 are connected to the access point 91. The access point 91 operates with power supplied from the solar power generator 21 and the storage battery 22. The access point 91 includes antennas 911 and 912, a wireless terminal communication processing unit 913, a wireless mesh communication processing unit 914, and an operation mode control unit 915.

  In the access point 91, the wireless terminal communication processing unit 913 performs communication with the wireless terminal 94 in the infrastructure mode via the antenna 911. The wireless mesh communication processing unit 914 communicates with the access point 92 and the access point 93 via the antenna 912.

  In the wireless communication system shown in the figure, the access point 91 has established a peer relationship with the access points 92 and 93, and the operation mode for each peer can be selected from Active mode / Light Sleep mode / Deep Sleep mode. it can. This selection is performed by the operation mode control unit 915. The operation mode control unit 915 notifies the wireless mesh communication processing unit 914 of the selected operation mode, and the wireless mesh communication processing unit 914 operates according to the operation mode selected for each peer.

  In order to operate the access point 91 with the least power consumption, it is necessary to operate in the Deep Sleep mode. Therefore, it is preferable that the Deep Sleep mode is selected as the operation mode for the access point 91 that operates with limited power of the solar power generator 21 and the storage battery 22 in order to extend the operable time.

  The wireless mesh communication processing unit 14 operating in the Deep Sleep mode for both peers can suppress power consumption. However, in the wireless mesh communication processing unit 14 that always operates in the Deep Sleep mode, the frame delay increases compared to the case in which the wireless mesh communication processing unit 14 operates in the Active mode or the Light Sleep mode. When power supplied from the solar power generator 21 and the storage battery 22 is scarce and there is a risk of leading to malfunction of the wireless communication system, it is unavoidable to allow communication quality deterioration such as frame delay. However, it is not preferable to cause communication quality deterioration such as frame delay until the remaining capacity of the storage battery 22 is sufficiently present and the amount of power generated from the solar power generator 21 can be expected.

  The present invention has been made in consideration of such circumstances, and its object is to save communication while suppressing deterioration in communication quality when access point devices operating with limited power communicate with each other. An object of the present invention is to provide an access point device, a control method for the access point device, and a wireless communication system capable of achieving power consumption.

  In order to solve the above-described problem, the present invention provides an access point device that includes a power source and a storage battery and operates by power supplied from the power source and the storage battery. A power source information processing unit to be acquired, a storage battery information processing unit for acquiring the amount of power stored in the storage battery, a wireless communication unit for performing wireless communication with other access point devices on a one-to-one line, and the power source Based on the amount of power acquired by the information processing unit and the amount of power acquired by the storage battery information processing unit, the storage battery depletion time, which is the time until the own access point device cannot operate due to lack of power, is calculated, Based on the calculated storage battery depletion time and the traffic amount of the line, the wireless communication unit is operated as an active mode in which communication is possible at all times, or intermittent communication is performed. An access point device, characterized in that it comprises an operation mode control unit whether to operate as a capacity of the sleep mode is determined for each of the line to control the wireless communication unit.

  Further, in the present invention described above, when the power source information processing unit detects the occurrence of a failure in the power source, the power amount supplied from the power source is set to zero, and the operation mode control is performed. The unit is characterized by recalculating the time required for storage battery depletion.

  In the invention described above, the present invention further includes an information storage unit that stores average data based on a past value of the amount of power supplied by the power source, and the operation mode control unit includes: The storage battery depletion time is calculated based on the average data.

  In the invention described above, the power source generates power using natural energy, and the information storage unit is based on a past value of the amount of power supplied by the power source. Average data for each weather is stored, the operation mode control unit estimates the weather based on the amount of power acquired by the power source information processing unit, and the storage battery based on the average data corresponding to the estimated weather The depletion time is calculated.

  Further, in the present invention described above, when the operation mode control unit calculates the storage battery depletion required time is less than a predetermined upper limit threshold and is equal to or greater than a predetermined lower limit threshold, The operation of the wireless communication unit is continued.

  In order to solve the above problem, the present invention includes a wireless communication unit that performs wireless communication with another access point device on a one-to-one line, a power source, and a storage battery, and is supplied from the power source and the storage battery. A power source information processing step for acquiring the amount of power supplied by the power source, and a storage battery information processing step for acquiring the amount of power stored in the storage battery. Based on the amount of power acquired in the power source information processing step and the amount of power acquired in the storage battery information processing, the storage battery depletion time, which is the time until the own access point device cannot operate due to power shortage, Based on the calculated storage battery depletion time and the traffic amount of the line, the wireless communication unit And an operation mode control step of controlling the wireless communication unit by determining for each line whether to operate as a sleep mode or to operate as a sleep mode capable of intermittent communication. Is the method.

  In order to solve the above-mentioned problem, the present invention includes a first access point device that includes a power source and a storage battery and operates by power supplied from the power source and the storage battery, and the first access. A wireless communication system including a second access point device that performs wireless communication with a point device on a one-to-one line, wherein the first access point device acquires an amount of power supplied by the power source An information processing unit; a storage battery information processing unit that acquires the amount of power stored in the storage battery; a wireless communication unit that performs wireless communication with the second access point device on a one-to-one line; and the power source information processing Time until the own access point device cannot operate due to lack of power based on the amount of power acquired by the storage unit and the amount of power acquired by the storage battery information processing unit The battery depletion time is calculated, and based on the calculated storage battery depletion time and the traffic amount of the line, the wireless communication unit is operated as an active mode in which communication is possible at all times or a sleep mode in which communication is intermittently performed. An operation mode control unit that determines whether to operate each line and controls the radio communication unit.

  According to this invention, based on the storage battery depletion required time and the traffic amount of each line, it is determined for each line whether the operation of the wireless communication unit is operated in the active mode or the sleep mode. The active mode can be selected for a line with a large amount of traffic, and the sleep mode can be selected for a line with a small amount of traffic when the time required for battery depletion is short. As a result, it is possible to save power while suppressing deterioration of communication quality, and it is possible to suppress the wireless communication system including the access point device operating with limited power from becoming inoperative. .

It is a schematic block diagram which shows the structure of the radio | wireless communications system in embodiment which concerns on this invention. It is a figure which shows an example of the average solar radiation amount data which the external information storage part 19 in the embodiment memorize | stores. It is a flowchart which shows the operation mode switching determination process which the operation mode control part 15 of the access point 1 in the embodiment performs. It is the schematic which shows the estimation method of the storage battery residual amount using Formula (4) by the operation mode control part 15 in the embodiment. It is a figure which shows an example of the peer management table in the same embodiment. It is a schematic block diagram which shows the structural example of the radio | wireless communications system which comprises the access point which communicates by a mesh structure.

  Hereinafter, an access point device (hereinafter referred to as an access point), an access point control method, and a wireless communication system according to an embodiment of the present invention will be described with reference to the drawings. Below, the case where a solar power generator is used for the electric power source of an access point as one embodiment, and communication between access points is performed according to IEEE802.11s standard is demonstrated.

  FIG. 1 is a schematic block diagram illustrating a configuration of a wireless communication system according to an embodiment of the present invention. As shown in the figure, the wireless communication system includes three access points 1, 2, and 3 and a wireless terminal 4. Access points 1, 2, and 3 are connected in a mesh configuration. The access point 1 constructs an access point 2 and a wireless mesh peer 31, and constructs an access point 3 and a wireless mesh peer 32. The wireless mesh peers 31 and 32 are lines between two access points using wireless communication. A wireless terminal 4 is connected to the access point 1 in the infrastructure mode.

  The access point 1 is connected to a solar power generator 21 and a storage battery 22 as power sources. The access point 1 operates with electric power supplied from the solar power generator 21 and the storage battery 22. As shown in the figure, the access point 1 includes antennas 11 and 12, a wireless terminal communication processing unit 13, a wireless mesh communication processing unit 14, an operation mode control unit 15, a communication status monitoring unit 16, sunlight, and the like. A generator information processing unit 17, a storage battery information processing unit 18, and an external information storage unit 19 are provided.

  In the access point 1, the wireless terminal communication processing unit 13 performs wireless communication with the wireless terminal 4 in the infrastructure mode via the antenna 11. The wireless mesh communication processing unit 14 performs wireless communication with the access points 2 and 3 via the antenna 12.

  The operation mode control unit 15 controls the operation mode of the wireless mesh communication processing unit 14. In the wireless communication system shown in FIG. 1, the access point 1 establishes a peer relationship with the access points 2 and 3, and the operation mode control unit 15 selects an operation mode for each of the wireless mesh peer 31 and the wireless mesh peer 32. The operation mode control unit 15 selects an operation mode of each of the wireless mesh peers 31 and 32 from the Active mode / Light Sleep mode / Deep Sleep mode. As described above, the Active (active) mode is an operation mode in which communication is always possible, and the sleep mode of Light Sleep and Deep Sleep is an operation mode in which communication is possible intermittently. The operation mode control unit 15 notifies the wireless mesh communication processing unit 14 of the selected operation mode, and the wireless mesh communication processing unit 14 operates according to the operation mode selected for each of the wireless mesh peers 31 and 32.

  In addition, the operation mode control unit 15 can request notification of the traffic volume recorded by the communication status monitoring unit 16, and the traffic volume of the wireless terminal communication processing unit 13 and the wireless mesh peer 31 can be transmitted via the communication status monitoring unit 16. And the traffic volume of the wireless mesh peer 32 can be acquired. Further, the operation mode control unit 15 can acquire information on the solar power generator 21, the storage battery 22, and the average solar radiation amount data stored in the external information storage unit 19. The average solar radiation amount data will be described later.

  The communication status monitoring unit 16 includes a traffic amount at a certain time of communication performed by the wireless terminal communication processing unit 13 via the antenna 11, and a traffic amount at a certain time of communication performed by the wireless mesh communication processing unit 14 via the antenna 12. Monitor and memorize. At this time, the communication status monitoring unit 16 monitors and stores the traffic volume of communication performed by the wireless mesh communication processing unit 14 via the antenna 12 for each wireless mesh peer. In response to a request from the operation mode control unit 15, the communication status monitoring unit 16 notifies the operation mode control unit 15 of the traffic volume in which the stored traffic volume is recorded.

  The solar power generator information processing unit 17 is connected to the solar power generator 21. The solar power generator information processing unit 17 detects the amount of power (solar power generation amount) generated by the solar power generator 21 at regular intervals, and stores the detected solar power generation amount in the external information storage unit 19.

  The storage battery information processing unit 18 is connected to the storage battery 22. The storage battery information processing unit 18 periodically detects the amount of power (storage battery remaining amount) stored in the storage battery 22 and stores the detected storage battery remaining amount in the external information storage unit 19.

  The external information storage unit 19 stores the amount of photovoltaic power generation detected by the photovoltaic power generator information processing unit 17 and the remaining amount of storage battery detected by the storage battery information processing unit 18. In addition, the external information storage unit 19 stores in advance average solar radiation amount data for each fixed time in each weather such as sunny, cloudy, and rainy at the location where the access point 1 is installed. This average solar radiation amount data includes data acquired in the past and data inferred from the acquired data, and in response to designation of a predetermined time including the month and day, the average solar radiation amount data for the predetermined time can be obtained. . An example of this data is shown in FIG.

FIG. 2 is a diagram illustrating an example of average solar radiation amount data stored in the external information storage unit 19 in the present embodiment. The average solar radiation amount data shown in the figure includes, for each period (..., T-2 to T-1, T-1 to T, T to T + 1, T + 1 to T + 2,. The amount of solar radiation at each hour is associated. For example, for the duration "T-1 to T ', fine weather" 0.9 kW / ^{m 2} ", a cloudy day" 0.5 kW / ^{m 2} ", and the rain correlated" 0.1 kW / ^{m 2} " It has been.

  Next, a procedure in which the operation mode control unit 15 of the access point 1 performs operation mode switching determination will be described. FIG. 3 is a flowchart showing an operation mode switching determination process performed by the operation mode control unit 15 of the access point 1 in the present embodiment. This operation mode switching determination process is executed at regular intervals. In the following description, a case where the operation mode control unit 15 performs the operation mode switching determination process at time T will be described.

  In the access point 1, the operation mode control unit 15 is activated with the time T as a trigger (step S 0), and based on the amount of photovoltaic power generation and the remaining battery level stored in the external information storage unit 19, The storage battery depletion time in 1 future is calculated (step S1). Here, the calculation procedure of the storage battery depletion time required by the operation mode control unit 15 will be described. The operation mode control unit 15 acquires from the external information storage unit 19 the amount of photovoltaic power generation in the periods (T-1) to T and the remaining amount of storage battery at time T. Further, the operation mode control unit 15 acquires the average solar radiation amount data during the fine weather, the cloudy weather, and the rainy weather in the periods (T-1) to T from the external information storage unit 19.

Operation mode control unit 15 is calculated as the period (T-1) following equation solar radiation _{I T} in through T (1).

In the formula (1), E _T is the photovoltaic power generation amount in a photovoltaic power generation amount period (T-1) ~T stored in the external information storage unit 19. α is the power generation efficiency of the solar power generator 21, S is the panel area of the solar power generator 21, and is determined according to the solar power generator 21 connected to the access point 1. t is a period of time (T-1) to T.

Next, the operation mode control unit 15, the period obtained from the external information storage unit 19 (T-1) in fine weather in through T, a cloudy day, compared with the respective average solar radiation data rainy weather and solar radiation I _T Te, selects the average solar radiation data I _'T which is the most approximate to the amount of solar radiation I _T in a period (T-1). The operation mode control unit 15 estimates the amount of solar radiation I _k (k = T + 1, T + 2,...) After time T as in the following equation (2). In the formula (2), solar radiation _{I 'k (k = T +} 1, T + 2, ...) is I are closest to solar radiation _{I T'} is the time sequence of the weather _T, d is the mean solar radiation data I ' which is the difference between the results of the _T and the amount of solar radiation I _T.

Furthermore, the operation mode control unit 15 estimates the photovoltaic power generation amount E _k (k = T + 1, T + 2,...) From the estimated amount of solar radiation I ′ _k after the estimated time T by Equation (3).

On the other hand, it is assumed that there is no significant change based on the traffic volume with the wireless terminal after time T, and the subsequent power consumption does not change. The operation mode control unit 15 estimates the remaining battery charge R _k at time k (k = T + 1, T + 2,...) By the following equation (4).

In equation (4), the power amount U _j (j = T + 1, T + 2,..., N) is the power consumption amount at times (j−1) to j. Here, since it is assumed that traffic volume does not _{change, U (T + 1) =} U (T + 2) = ... = a _{U N.} The time _k at which R _k = 0 for the first time after time T is the expected storage battery depletion time, and the storage battery depletion required time D is obtained by k−T.

In other words, the calculation method of the storage battery depletion time D is the solar radiation amount I ′ _k determined based on the photovoltaic power generation amount E _k , the power generation efficiency α of the solar power generator 21, and the panel area S of the solar power generator 21. This is a method of preparing a plurality of regression equations with variables of time and time, selecting the regression equation that is the most approximate, and estimating the future power generation amount. In this method, it is also possible to prepare and estimate a regression equation using the solar power generation amount E _T and time as variables without performing conversion to the solar radiation amount I ′ _k . There is no limit to the number of regression equations to prepare. Further, actually, solar power generation amount E _T was measured, using the calculated solar radiation amount I _'k, it is possible to increase the accuracy of the regression equation.

  FIG. 4 is a schematic diagram illustrating a method for estimating the remaining amount of storage battery using Expression (4) by the operation mode control unit 15 in the present embodiment. In the figure, the horizontal axis indicates time, and the vertical axis indicates power consumption, power source power generation amount (photovoltaic power generation amount), and storage battery remaining amount. In the figure, measured values and predicted values of the power consumption U, the power source power generation amount E, and the remaining battery charge R during the period from time (T-1) to time (T + 2) are shown. The figure shows a case where the power source power generation amount increases and the storage battery remaining amount R increases accordingly.

  In addition, when the amount of photovoltaic power generation continues to be zero even though it is not nighttime or bad weather, the storage battery is depleted because the photovoltaic power generator 21 has failed and the power supply to the access point 1 has been interrupted. The expected time and storage battery depletion time D are calculated. For example, the solar power generator information processing unit 17 notifies the operation mode control unit 15 of the occurrence of a failure when the power generation amount of the solar power generator 21 continues to be 0, and the operation mode control unit 15 notifies the storage battery 22. Based on the amount of stored electric power, the estimated time of storage battery depletion and the required time D for storage battery depletion are recalculated. That is, the solar power generator information processing section 17 outputs the power generation amount of the solar power generator 21 to the operation mode control section 15 as 0 (zero).

  The operation mode control unit 15 determines whether or not the storage battery depletion required time D calculated in Step S1 is less than the upper limit threshold β (Step S2). This upper limit threshold β is a predetermined value, and when the storage battery depletion time D is equal to or greater than the upper limit threshold β, a value that is considered to have a grace period before the amount of power stored in the storage battery is depleted is set. Is done. When the storage battery depletion required time D is equal to or greater than the upper limit threshold β (step S2: NO), the operation mode control unit 15 advances the process to a process for improving communication quality (step S3 to step S6).

  In the subsequent processing, the operation mode control unit 15 uses the peer management table shown in FIG. For example, the peer management table is provided in advance in the operation mode control unit 15. FIG. 5 is a diagram showing an example of the peer management table in the present embodiment. As shown in the figure, the peer management table has items of a wireless mesh peer name, an operation mode before change, an operation mode after change, and a priority. Each row of the peer management table exists for each peer (one-to-one communication line with another access point or wireless mesh peer) in the own access point, and has a value of each item of the peer. The wireless mesh peer name is a name or identifier for identifying the peer. The pre-change operation mode indicates the current operation mode, and an operation mode of Active mode / Light Sleep mode / Deep Sleep mode is set. The post-change operation mode is set to the same operation mode as the pre-change operation mode as an initial value. The priority is a numerical value indicating the priority with respect to the traffic volume of the peer, and a higher priority is set for a peer with a larger traffic volume. When a plurality of peers have the same amount of traffic, a higher priority is set for a peer that has a lot of traffic used for communication with a wireless terminal connected to its own access point.

  When the storage battery depletion time D is equal to or greater than the upper limit threshold β, the operation mode control unit 15 determines whether or not there is a peer whose operation mode after change is the Deep Sleep mode in the peer management table (step S3). When there is a deep sleep mode peer (step S3: YES), the operation mode control unit 15 provisionally updates the operation mode after the change of the highest priority among the deep sleep mode peers from the deep sleep mode to the light sleep mode ( Step S4), the process proceeds to step S13.

  When there is no deep sleep mode peer (step S3: NO), the operation mode control unit 15 determines whether there is a peer whose operation mode after change is the light sleep mode in the peer management table (step S5). When there is a peer in the Light Sleep mode (step S5: YES), the operation mode control unit 15 provisionally updates the changed operation mode of the peer having the highest priority among the peers in the Light Sleep mode to the Active mode (step S6). Then, the process proceeds to step S13.

  When there is no Light Sleep mode peer (step S5: NO), that is, all the peers are in the active mode, and there is no peer that switches the operation mode in order to improve the communication quality. The control part 15 advances a process to step S12.

  In step S2, when the storage battery depletion required time D is less than the upper limit threshold β (step S2: YES), the operation mode control unit 15 determines whether or not the storage battery depletion required time D exceeds the lower limit threshold γ (step S7). ). When the storage battery depletion required time D exceeds the lower limit threshold γ (step S7: YES), the operation mode control unit 15 advances the process to step S12.

  On the other hand, when the storage battery depletion required time D is equal to or less than the lower limit threshold γ (step S7: NO), the operation mode control unit 15 determines that there is a concern about the depletion of the remaining storage battery (step S8). The process proceeds to step S11). The operation mode control unit 15 determines whether or not there is a peer whose operation mode after change is the Active mode in the peer management table (step S8).

  When there is an active mode peer (step S8: YES), the operation mode control unit 15 temporarily changes the post-change operation mode of the peer with the lowest priority among the active mode peers to the light sleep mode (step S9). Then, the process proceeds to step S13.

  When there is no active mode peer (step S8: NO), the operation mode control unit 15 determines whether there is a light sleep mode peer (step S10). When there is a light sleep mode peer (step S10: YES), the operation mode control unit 15 temporarily changes the operation mode after the piano change having the lowest priority among the light sleep mode peers to the deep sleep mode (step S11). The process proceeds to step S13.

  When there are no Light Sleep mode peers (step S10: NO), that is, all the peers are operating in Deep Sleep mode. In this state, the operation mode control unit 15 advances the process to step S12.

Step S4, S6, S9, or after executing the processing of any of S11, the operation mode control section 15 utilizes solar power generation amount E _T calculated in step S1, to calculate the battery depletion duration D again (Step S13). Assuming a case where each peer of the wireless mesh communication processing unit 14 operates in the operation mode indicated in the operation mode after change of the peer management table during the period (T-1) to T, each state (transmission state, The product of the accumulated time of the reception state, the standby state, and the Doze state) and the power consumption is calculated, and the power consumption is calculated again. The access point power consumption in each state is assumed to be known. Operation mode control section 15 includes a power consumption amount calculated again, using the photovoltaic power generation amount E _T calculated in step S1, recalculates the battery depletion duration D. The operation mode control unit 15 repeats the processing from step S2 again using the storage battery depletion required time D calculated in step S13.

  The operation mode control unit 15 changes the operation mode according to the determination result of step S5 or the determination result of step S10. Specifically, the operation mode control unit 15 detects peers having different operation modes set in the pre-change operation mode and the post-change operation mode in the peer management table, and changes the detected operation mode of the peer. Change to the operation mode set in the operation mode. The operation mode control unit 15 controls the wireless mesh communication processing unit 14 to operate in the operation mode set to the operation mode after change for the detected peer. Note that the operation mode control unit 15 does not change the operation mode for peers in which the pre-change operation mode and the post-change operation mode are the same.

  In the wireless communication system of the above-described embodiment, supplied when the access point 1 operating with limited power from the solar power generator 21 and the storage battery 22 communicates with other access points in a mesh configuration. The operation mode of each peer is switched based on the state of the amount of power that is generated and the amount of traffic in a peer (communication line) with another access point. For example, when the storage battery depletion time D is equal to or greater than a predetermined upper limit threshold β, the operation mode of the peer with the highest priority is changed to the Active mode, and the storage battery depletion time D is set to the predetermined lower threshold γ. In the following cases, the operation mode of the peer with the lowest priority is changed from the Active mode to the Sleep mode. As a result, it is possible to reduce the power consumption of the access point 1 while suppressing the occurrence of a communication frame delay between the access points. As a result, it is possible to prevent the access point 1 operating with limited power from stopping due to insufficient power and causing the wireless communication system to become inoperable.

  Note that a mode switching determination is made by recording a program for realizing the function of the access point 1 in FIG. 1 on a computer-readable recording medium, causing the computer system to read and execute the program recorded on the recording medium. Processing may be performed. Here, the “computer system” includes an OS and hardware such as peripheral devices. The “computer-readable recording medium” refers to a storage device such as a flexible medium, a magneto-optical disk, a portable medium such as a ROM and a CD-ROM, and a hard disk incorporated in a computer system. Further, the “computer-readable recording medium” refers to a volatile memory (RAM) in a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. In addition, those holding programs for a certain period of time are also included.

  The program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the “transmission medium” for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for realizing a part of the functions described above. Furthermore, what can implement | achieve the function mentioned above in combination with the program already recorded on the computer system, and what is called a difference file (difference program) may be sufficient.

As mentioned above, although embodiment of this invention has been described with reference to drawings, said embodiment is only the illustration of this invention, and it is clear that this invention is not limited to said embodiment. . Accordingly, additions, omissions, substitutions, and other changes of the components may be made without departing from the technical idea and scope of the present invention.
For example, in the above embodiment, the configuration in which the wireless communication system includes the three access points 1, 2, and 3 has been described. However, the configuration may include two or four or more access points. Further, the wireless communication system may be configured to include a plurality of access points that operate with limited power.
In the above embodiment, the configuration in which the access point included in the wireless communication system communicates in a mesh configuration has been described. However, the access point may be configured to communicate with other devices via a plurality of communication lines. Good.

In the above embodiment, the configuration in which the solar power generator 21 is connected to the access point 1 has been described. However, instead of the solar power generator 21, a power source that generates power using other natural energy is connected. May be. For example, a power source having a power generation capability such as a wind power generator or a geothermal power generator may be connected to the access point 1.
In the above embodiment, the configuration in which the operation mode control unit 15 included in the access point 1 determines the operation mode has been described. However, a higher-level device connected to the access point 1 accesses the operation mode control unit 15 instead of the access mode 1. You may make it determine the operation mode in each peer of the point 1. FIG.

  The present invention relates to a wireless communication system that performs wireless communication between access point devices that operates with power supplied from a power source and a storage battery, and smoothes the storage battery depletion time and suppresses the occurrence of communication delay. This is expected to extend the life of the depletion period and reduce the size of the station design, so it can be applied to applications that require temporary network construction such as outdoor events and disaster shelters.

1, 2, 3, 91, 92, 93 ... access point 4, 94 ... wireless terminal 11, 12, 911, 912 ... antenna 13, 913 ... wireless terminal communication processing unit 14, 914 ... wireless mesh communication processing unit 15, 915 Operation mode control unit 16 Communication state monitoring unit 17 Solar power generator information processing unit 18 Storage battery information processing unit 19 External information storage unit 21 Solar power generator 22 Storage battery 31, 32 Wireless mesh peer

Claims (7)

An access point device comprising a power source and a storage battery and operating with power supplied from the power source and the storage battery,
A power source information processing unit for acquiring the amount of power supplied by the power source;
A storage battery information processing unit for acquiring the amount of power stored in the storage battery;
A wireless communication unit that performs wireless communication with other access point devices on a one-to-one line;
Based on the amount of power acquired by the power source information processing unit and the amount of power acquired by the storage battery information processing unit, the storage battery depletion time, which is the time until the own access point device cannot operate due to power shortage, Based on the calculated storage battery depletion required time and the traffic amount of the line, whether to operate the wireless communication unit as an active mode capable of always communicating or as a sleep mode capable of intermittent communication An access point device comprising: an operation mode control unit configured to determine for each line and control the wireless communication unit. The access point device according to claim 1,
The power source information processing unit, when detecting the occurrence of a failure in the power source, sets the amount of power supplied from the power source to zero,
The access point device, wherein the operation mode control unit recalculates a storage battery depletion time. The access point device according to claim 1 or 2,
An information storage unit storing average data based on past values of the amount of power supplied by the power source;
The access point device, wherein the operation mode control unit calculates a storage battery depletion time based on the average data. The access point device according to claim 3,
The power source uses natural energy to generate power,
The information storage unit stores average data for each weather based on the past value of the amount of power supplied by the power source,
The operation mode control unit estimates the weather based on the amount of power acquired by the power source information processing unit, and calculates a storage battery depletion time based on the average data corresponding to the estimated weather. Access point device. The access point device according to any one of claims 1 to 4,
The operation mode control unit continues the current operation of the wireless communication unit when the calculated storage battery depletion time is less than a predetermined upper limit threshold and is equal to or greater than a predetermined lower limit threshold. Access point device. A control method for an access point device, comprising a wireless communication unit that performs wireless communication with another access point device on a one-to-one line, a power source, and a storage battery, and operated by power supplied from the power source and the storage battery. ,
A power source information processing step for obtaining the amount of power supplied by the power source;
A storage battery information processing step for acquiring the amount of power stored in the storage battery;
Based on the amount of power acquired in the power source information processing step and the amount of power acquired in the storage battery information processing step, the storage battery depletion time, which is the time until the own access point device cannot operate due to power shortage, Based on the calculated storage battery depletion required time and the traffic amount of the line, whether to operate the wireless communication unit as an active mode capable of always communicating or as a sleep mode capable of intermittent communication And an operation mode control step for controlling the wireless communication unit by determining for each line. A first access point device comprising a power source and a storage battery and operating with power supplied from the power source and the storage battery, and a second wireless communication with the first access point device via a one-to-one line A wireless communication system comprising the access point device of
The first access point device is
A power source information processing unit for acquiring the amount of power supplied by the power source;
A storage battery information processing unit for acquiring the amount of power stored in the storage battery;
A wireless communication unit that performs wireless communication with the second access point device on a one-to-one line;
Based on the amount of power acquired by the power source information processing unit and the amount of power acquired by the storage battery information processing unit, the storage battery depletion time, which is the time until the own access point device cannot operate due to power shortage, Based on the calculated storage battery depletion required time and the traffic amount of the line, whether to operate the wireless communication unit as an active mode capable of always communicating or as a sleep mode capable of intermittent communication A wireless communication system comprising: an operation mode control unit that determines each line and controls the wireless communication unit.

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