Wireless communication systems, communication devices, wireless communication methods, and programs

Abstract

This suppresses the degradation of communication reliability during power-up. [Solution] The wireless communication system comprises a plurality of communication terminals 100, including one communication terminal 100A. The one communication terminal 100A has a calculation unit 141 and a wireless communication unit 12. The calculation unit 141 calculates a backoff time based on a single identification piece of information when the power is started up. The wireless communication unit 12 transmits the first wireless signal to be transmitted after the power has started up, after the backoff time has elapsed. The single identification piece of information is the identification piece of information assigned to the one communication terminal 100A from among a plurality of identification pieces of information assigned to each of the plurality of communication terminals 100.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, a communication device, a wireless communication method, and a program. More specifically, the present disclosure relates to a wireless communication system, a communication device, a wireless communication method, and a program including a plurality of communication terminals.

Background Art

[0002] Patent Document 1 describes a method for determining a backoff time for determining a backoff time. In the method for determining the backoff time described in Patent Document 1, the backoff time is determined so that the transmission timing of a future control signal by a wireless terminal to be backed off does not overlap with a period in which the number of occurrences per unit time exceeds a reference value in a predicted signal distribution indicating the distribution of the number of occurrences of future control signals.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, in the method for determining the backoff time described in Patent Document 1, for example, the reliability of communication may be reduced due to the occurrence of burst traffic at the time of power startup.

[0005] An object of the present disclosure is to provide a wireless communication system, a communication device, a wireless communication method, and a program capable of suppressing a decrease in communication reliability at the time of power startup.

Means for Solving the Problems

[0006] A wireless communication system according to one aspect of the present disclosure comprises a plurality of communication terminals, including one communication terminal. The one communication terminal includes a calculation unit and a wireless communication unit. The calculation unit calculates a backoff time based on a single piece of identification information when the power is started up. The single piece of identification information is the identification information assigned to the one communication terminal from among a plurality of identification pieces of identification information assigned to each of the plurality of communication terminals. The wireless communication unit transmits the first wireless signal to be transmitted after the power is started up, after the backoff time has elapsed.

[0007] A communication device according to one aspect of this disclosure is used as the communication terminal in the wireless communication system.

[0008] A wireless communication method according to one aspect of the present disclosure comprises a calculation step and a wireless communication step. In the calculation step, a backoff time is calculated based on a single identification piece of information when the power supply is started. The single identification piece of information is an identification piece of information assigned to one of a plurality of identification pieces of information assigned to each of a plurality of communication terminals. In the wireless communication step, the first wireless signal to be transmitted after the power supply has started is transmitted after the backoff time has elapsed.

[0009] A program according to one aspect of this disclosure is a program for causing one or more processors to execute the wireless communication method. [Effects of the Invention]

[0010] According to one aspect of this disclosure, a wireless communication system, communication device, wireless communication method, and program make it possible to suppress the deterioration of communication reliability when the power is started up. [Brief explanation of the drawing]

[0011] [Figure 1] Figure 1 is a system configuration diagram of a wireless communication system according to an embodiment of this system. [Figure 2] Figure 2 is a block diagram of the lighting device in the wireless communication system described above. [Figure 3]Figure 3 is a block diagram of the sensor device in the wireless communication system described above. [Figure 4] Figure 4 is a block diagram of the communication equipment in the wireless communication system described above. [Figure 5] Figure 5 is a block diagram of the tablet in the wireless communication system described above. [Figure 6] Figure 6 is a block diagram of the handheld remote control in the same wireless communication system. [Figure 7] Figure 7 is an explanatory diagram of the mesh network used in the wireless communication system described above. [Figure 8] Figure 8 is a diagram showing the layout of areas and zones in the wireless communication system described above. [Figure 9] Figure 9 is a flowchart of the wireless communication method performed by the wireless communication system described above. [Figure 10] Figure 10 is another flowchart of the wireless communication method performed by the same wireless communication system. [Figure 11] Figure 11 is a timing chart showing the operation of the wireless communication system described above. [Modes for carrying out the invention]

[0012] Hereinafter, a wireless communication system, communication device, wireless communication method, and program according to the embodiments will be described with reference to the drawings. However, the configurations described in the following embodiments are merely examples of the present disclosure. The present disclosure is not limited to the following embodiments, and various modifications are possible depending on the design, etc., as long as the effects of the present disclosure can be achieved.

[0013] (Embodiment) (1) Overview First, an overview of the wireless communication system S1 and communication device (lighting device A1) according to this embodiment will be described with reference to Figures 1 and 2.

[0014] The wireless communication system S1 according to the embodiment is installed in, for example, commercial facilities such as office buildings and shopping centers, factories, warehouses, public facilities such as libraries, etc. Note that the above facilities are just examples, and the places where the wireless communication system S1 according to the embodiment is installed are not limited to the above facilities.

[0015] As shown in FIG. 1, the wireless communication system S1 according to the embodiment includes a plurality of communication terminals 100 including one communication terminal 100A. As shown in FIG. 2, one communication terminal 100A has a calculation unit 141 and a wireless communication unit 12. When the power supply is activated, the calculation unit 141 calculates a back-off time T1 (see FIG. 9) based on one identification information. One identification information is the identification information assigned to one communication terminal 100A among the plurality of identification information respectively assigned to the plurality of communication terminals 100. The wireless communication unit 12 transmits the wireless signal first transmitted after the power supply is activated after the back-off time T1 has elapsed. In this specification and the like, "when the power supply is activated" means that the power supply state changes from a non-power-supplied state where no power is supplied to a power-supplied state where power is supplied.

[0016] In the wireless communication system S1 according to the embodiment, the calculation unit 141 calculates the back-off time T1 based on one identification information, and the wireless communication unit 12 transmits the wireless signal after the back-off time T1 has elapsed. As a result, burst traffic is less likely to occur when the power supply is activated, and thus it is possible to suppress a decrease in communication reliability when the power supply is activated.

[0017] Also, as shown in FIGS. 1 and 2, the lighting device A1 (communication device) according to the embodiment is used as one communication terminal 100A in the wireless communication system S1. According to the lighting device A1 according to the embodiment, it is possible to suppress a decrease in communication reliability when the power supply is activated.

[0018] (2) Details Next, each component of the wireless communication system S1 according to the embodiment will be described with reference to FIGS. 1 to 6.

[0019] (2.1) System Configuration As shown in Figure 1, the wireless communication system S1 according to this embodiment includes, for example, a plurality of lighting devices A1, a sensor device B1, a communication device D1, a tablet C1, and a handheld remote control C2. In this embodiment, as an example, the wireless communication system S1 is used in a lighting control system (hereinafter also referred to as "lighting control system S1") that controls a plurality of lighting devices A1.

[0020] Multiple lighting devices A1, sensor devices B1, and communication devices D1 are supplied with AC power from an external power source P1 via a two-wire power supply circuit P11. In the example shown in Figure 1, a switch device J1 is inserted into the power supply circuit P11. The switch device J1 is equipped with an operating handle J11 and is configured to turn the connection between the external power source P1 and the power supply circuit P11 on or off each time the operating handle J11 is operated. In other words, when the switch device J1 is turned on, AC power is supplied from the external power source P1 via the power supply circuit P11, enabling the wireless communication system S1 to operate. On the other hand, when the switch device J1 is turned off, AC power is not supplied from the external power source P1 via the power supply circuit P11, so the wireless communication system S1 becomes inoperable.

[0021] In this embodiment, the three lighting devices A1 included in the wireless communication system S1 function as a single communication terminal 100A. Furthermore, in this embodiment, each of the sensor device B1 and the communication device D1 functions as a communication terminal 100 distinct from the single communication terminal 100A. That is, the wireless communication system S1 according to this embodiment comprises multiple communication terminals 100, including a single communication terminal 100A. In short, the three lighting devices A1 (communication devices) are used as a single communication terminal 100A in the wireless communication system S1.

[0022] (2.1.1) Lighting devices Each of the multiple lighting devices A1 has a light source unit 10, a power supply unit 11, a wireless communication unit 12, a storage unit 13, and a control unit 14, as shown in Figure 2. As described above, lighting device A1 functions as one communication terminal 100A. The remaining lighting devices A1 of the multiple lighting devices A1 function as communication terminals 100 different from one communication terminal 100A. In the following description, when it is necessary to distinguish between the three lighting devices A1 that function as one communication terminal 100A, the three lighting devices A1 may be referred to as lighting devices A11, A12, and A13, respectively.

[0023] The light source unit 10 has, for example, an LED module configured by mounting multiple LEDs on a substrate. Note that the multiple light source units 10 in multiple lighting devices A1 may be of different types. For example, the multiple light source units 10 include a light source unit 10 that emits monochromatic illumination light, a light source unit 10 with a variable color temperature of illumination light, a light source unit 10 with a variable light color of illumination light, and a light source unit 10 with a switchable illumination direction. The light source unit 10 with a variable color temperature of illumination light has LED modules that emit illumination light of different color temperatures (e.g., incandescent and daylight). The light source unit 10 with a variable light color of illumination light has LED modules that emit illumination light of different colors, such as red, green, and blue light. Furthermore, the light source unit 10 with a switchable illumination direction has, for example, an LED module that emits illumination light towards the floor and an LED module that emits illumination light towards the ceiling or wall.

[0024] The power supply unit 11 includes, for example, a power conversion circuit and a constant current circuit. The power conversion circuit converts AC power supplied from an external power supply P1 via a power supply line P11 into DC power. The constant current circuit operates to match the DC current supplied to the light source unit 10 to a target value. The power supply unit 11 may have multiple constant current circuits depending on the type of light source unit 10. That is, a power supply unit 11 paired with a light source unit 10 whose illumination light color temperature is variable has multiple constant current circuits that supply DC current individually to multiple LED modules with different color temperatures. Also, a power supply unit 11 paired with a light source unit 10 whose illumination light color is variable has multiple constant current circuits that supply DC current individually to LED modules with multiple light colors. Furthermore, a power supply unit 11 paired with a light source unit 10 whose irradiation direction is switchable has, for example, a constant current circuit that supplies DC current to an LED module that radiates illumination light toward the floor, and a constant current circuit that supplies DC current to an LED module that radiates illumination light toward the ceiling or wall.

[0025] The wireless communication unit 12 includes a wireless communication circuit and an antenna. The wireless communication circuit is an integrated circuit configured to perform wireless communication compliant with wireless communication standards, such as BLE (Bluetooth® low energy), and mesh communication using radio waves as a medium. The wireless communication circuit may also be configured to perform wireless communication compliant with wireless communication standards other than BLE, such as Wi-Fi®, ZigBee®, or 920MHz band low-power radio stations (for telecontrol). The wireless communication circuit can send and receive wireless signals through the antenna. The wireless communication unit 12 transmits the first wireless signal to be sent after the power is turned on, after a backoff time T1 (see Figure 11) has elapsed. The wireless communication unit 12 also periodically transmits a second wireless signal that is transmitted after the first wireless signal, which is the first wireless signal to be sent after the power is turned on. That is, the wireless communication unit 12 transmits the second wireless signal, which is transmitted from the second time onward, at a preset transmission period (interval).

[0026] The storage unit 13 has, for example, an electrically rewritable non-volatile semiconductor memory. The storage unit 13 stores identification information (one identification information) assigned to the lighting device A1 (one communication terminal 100A). The identification information includes, for example, a MAC address. The storage unit 13 may also store a backoff time T1 (see Figure 11). In this specification, "backoff time" means the waiting time from when the power supply is started until the first wireless signal is transmitted.

[0027] Furthermore, the memory unit 13 stores multiple scene information. Each of the multiple scene information includes lighting-related information and mode specification information. The lighting-related information is information for specifying at least one of the following: illumination intensity, light color, and irradiation direction. The mode specification information is information for specifying one control mode from among multiple control modes. Here, the power supply unit 11 adjusts the amount of light output by adjusting the DC current supplied to the light source unit 10. The illumination intensity is expressed by the dimming level of the light source unit 10. The dimming level is defined as the ratio of the light amount when the light amount when the rated current is flowed through the light source unit 10 is set to 100%. For example, a dimming level of 50% indicates that half the rated light amount is output from the light source unit 10. The light color is defined by the color temperature when the color temperature of the illumination light from the light source unit 10 is variable. However, the lighting-related information that specifies the light color is indicated by the ratio of the light amounts for each of several types of LED modules with different color temperatures. Similarly, if the light color of the light source unit 10 is variable, the lighting information specifying the light color is indicated by the ratio of light intensity for each LED module of each color. Furthermore, the lighting information specifying the irradiation direction of the light source unit 10 is indicated, for example, by a numerical value corresponding to the irradiation direction (e.g., 0: downward, 1: upward).

[0028] The control unit 14 mainly consists of a microcontroller. The control unit 14 is configured to perform various processes related to lighting control by having the microcontroller's processor execute a program for lighting control. Based on the wireless signal received by the wireless communication unit 12, the control unit 14 selects one scene information from among multiple scene information stored in the storage unit 13 and controls the power supply unit 11 based on the selected scene information.

[0029] Furthermore, the control unit 14 includes a calculation unit 141, as shown in Figure 2. The calculation unit 141 calculates the backoff time T1 based on a single piece of identification information when the power is started up. The single piece of identification information is the identification information assigned to one communication terminal 100A from among multiple pieces of identification information assigned to each of the multiple communication terminals 100. As mentioned above, the identification information includes, for example, a MAC address.

[0030] More specifically, the calculation unit 141 sets a predetermined value in one of the multiple numerical ranges that includes the input value as the backoff time T1. That is, the backoff time T1 is a predetermined value in one of the multiple numerical ranges that includes the input value. The input value is, for example, at least a part of a set of identification information. The predetermined value is, for example, the maximum value in one of the numerical ranges.

[0031] Specifically, consider a case where multiple numerical ranges include a first numerical range, a second numerical range, a third numerical range, and a fourth numerical range. The first numerical range is, for example, the range from 0 to less than 100. The second numerical range is, for example, the range from 100 to less than 200. The third numerical range is, for example, the range from 200 to less than 300. The fourth numerical range is the range of 300 or more. At least a part of the input value, which is a piece of identification information, is, for example, the last three digits of a MAC address. That is, the calculation unit 141 calculates the backoff time T1 based on, for example, the last three digits of a MAC address.

[0032] If the last three digits of the MAC address are between 0 and 100 (exclusive), the input value falls within the first numerical range, and the predetermined backoff time T1 is set to 100 μs, which is the maximum value within the first numerical range. If the last three digits of the MAC address are between 100 and 200 (exclusive), the input value falls within the second numerical range, and the predetermined backoff time T1 is set to 200 μs, which is the maximum value within the second numerical range. If the last three digits of the MAC address are between 200 and 300 (exclusive), the input value falls within the third numerical range, and the predetermined backoff time T1 is set to 300 μs, which is the maximum value within the third numerical range. If the last three digits of the MAC address are 300 or greater, the input value falls within the fourth numerical range, and the predetermined backoff time T1 is set to, for example, 400 μs.

[0033] (2.1.2) Sensor device As shown in Figure 3, the sensor device B1 includes a brightness detection unit 20, a human detection unit 21, a sensor control unit 22, a wireless communication unit 23, and a storage unit 24. As described above, the sensor device B1 functions as a communication terminal 100 different from one communication terminal 100A.

[0034] The brightness detection unit 20 includes, for example, a photoelectric conversion element and a signal processing circuit. The signal processing circuit processes the output signal of the photoelectric conversion element. The brightness detection unit 20 detects reflected light from the floor or desk surface within the detection range as the amount of incident light, converts the detected amount of incident light into a voltage signal (brightness signal), and outputs it to the sensor control unit 22.

[0035] The human detection unit 21 includes a passive type sensor that detects heat rays (infrared rays) emitted from the human body, generally called a heat ray sensor or PIR (Passive Infrared) sensor. The human detection unit 21 may also include an active type sensor that detects a person (moving object) by emitting radio waves (microwaves) and receiving the radio waves reflected by an antenna after they hit an object in space, thereby determining whether or not the object is moving. When the human detection unit 21 detects the presence of a person in the detection area, it outputs a human detection signal to the sensor control unit 22.

[0036] The brightness detection unit 20 and the person detection unit 21 may each have a single image sensor, and the system may be configured to detect a person from the difference between the background image acquired by the image sensor and the current image, as well as to detect brightness from the acquired image.

[0037] The sensor control unit 22 primarily consists of a microcontroller. The sensor control unit 22 is configured to perform various processes related to sensor control by having the microcontroller's processor execute a program for sensor control.

[0038] The sensor control unit 22 compares the brightness (illuminance within the detection range) indicated by the brightness signal input from the brightness detection unit 20 with the brightness target value, and creates a control command necessary to keep the difference between the illuminance within the detection range and the brightness target value within a predetermined range. For example, if the difference between the illuminance within the detection range and the brightness target value is greater than the upper limit of the predetermined range, the sensor control unit 22 creates a control command to lower the dimming level in order to reduce the difference between the illuminance within the detection range and the brightness target value. Conversely, if the difference between the illuminance within the detection range and the brightness target value is smaller than the lower limit of the predetermined range, the sensor control unit 22 creates a control command to raise the dimming level in order to reduce the difference between the illuminance within the detection range and the brightness target value. The sensor control unit 22 outputs the created control command to the wireless communication unit 23.

[0039] The wireless communication unit 23, like the wireless communication unit 12 of the lighting device A1, includes a wireless communication circuit and an antenna. The wireless communication circuit is an integrated circuit configured to perform wireless communication and mesh communication in accordance with the same wireless communication standards as the wireless communication circuit of the wireless communication unit 12. The wireless communication circuit can send and receive wireless signals through the antenna. The wireless communication unit 23 transmits messages, including control commands received from the sensor control unit 22, via wireless signals.

[0040] The memory unit 24 has, for example, an electrically rewritable non-volatile semiconductor memory. The memory unit 24 stores multiple scene information. Each scene information stored in the memory unit 24 matches the scene information stored in the memory unit 13 of the lighting device A1. More specifically, each scene information stored in the memory unit 24 includes the same mode specification information as the mode specification information stored in the memory unit 13 of the lighting device A1, and information regarding the operation of the sensor device B1.

[0041] (2.1.3) Communication equipment As shown in Figure 4, the communication device D1 includes a clock unit 40, a schedule storage unit 41, a schedule control unit 42, and a wireless communication unit 43. As described above, the communication device D1 functions as a communication terminal 100 different from one communication terminal 100A.

[0042] The clock unit 40 includes, for example, a real-time clock module. The real-time clock module is an integrated circuit configured to generate and output digital data including the time and date from a clock source. The clock unit 40 outputs the digital data of the time and date (hereinafter also referred to as "clock data") generated by the real-time clock module to the schedule control unit 42.

[0043] The schedule storage unit 41 has an electrically rewritable non-volatile semiconductor memory. The schedule storage unit 41 stores a schedule for lighting control. The schedule includes, for example, a combination of time zones and specification information that specifies scene information.

[0044] The schedule control unit 42 primarily consists of a microcontroller. The schedule control unit 42 is configured to perform various processes related to schedule control by having the microcontroller's processor execute a program for schedule control. The schedule control unit 42 refers to the clock data obtained from the clock unit 40 and the schedule stored in the schedule storage unit 41, and when the current time in the clock data matches the start time of the schedule, it creates a control command from the schedule specification information and outputs it to the wireless communication unit 43.

[0045] The wireless communication unit 43, like the wireless communication unit 12 of the lighting device A1, includes a wireless communication circuit and an antenna. The wireless communication circuit is an integrated circuit configured to perform wireless communication and mesh communication in accordance with the same wireless communication standards as the wireless communication circuit of the wireless communication unit 12. The wireless communication circuit can send and receive wireless signals through the antenna. The wireless communication unit 43 transmits messages, including control commands received from the schedule control unit 42, via wireless signals.

[0046] Furthermore, if the microcontroller of the schedule control unit 42 is equipped with a real-time clock module, the clock function may be implemented using the real-time clock module of the microcontroller.

[0047] As described above, the communication device D1 transmits control commands to the lighting device A1 using clock data as a trigger input, and therefore can also play the role of a control device in the lighting control system S1.

[0048] (2.1.4) Tablet As shown in Figure 1, the tablet C1 is a portable computer system configured by housing, for example, an SoC (System on a chip) and a touch panel display device C10 in a rectangular, plate-shaped enclosure C11.

[0049] An SoC is a single-chip semiconductor device that incorporates a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), and a modem, among other components. The touch panel display device C10 is, for example, a touch panel liquid crystal display or a touch panel organic EL (Electro-Luminescence) display.

[0050] In the wireless communication system S1, the various functions of the tablet C1 are realized by having the SoC (CPU) execute control programs (application programs) and schedule setting programs (application programs).

[0051] As shown in Figure 5, the tablet C1 includes an input receiving unit 30, a control unit 31, and a wireless communication unit 32. The input receiving unit 30 is implemented by the touch panel of the tablet C1. The control unit 31 is implemented by the CPU of the tablet C1. The wireless communication unit 32 is implemented by the modem of the tablet C1. The wireless communication unit 32 is configured to perform wireless communication compliant with standards such as BLE and Wi-Fi (registered trademark).

[0052] As shown in Figure 5, the control unit 31 includes a creation unit 311. The creation unit 311 creates scene information, including lighting-related information and mode specification information, in response to operation inputs received by the input receiving unit 30.

[0053] (2.1.5) Handheld remote control As shown in Figure 1, the handheld remote control C2 has a main body C20 made of a rectangular parallelepiped-shaped synthetic resin molded body. The main body C20 is small enough for a person to hold in one hand. Multiple (six in the illustrated example) operation buttons C21 to C26 are provided on the front of the main body C20.

[0054] As shown in Figure 6, the handheld remote control C2 includes an input receiving unit 50, a control unit 51, and a wireless communication unit 52. The input receiving unit 50, the control unit 51, and the wireless communication unit 52 are housed in the main body C20 of the handheld remote control C2.

[0055] The input receiving unit 50 has six tact switches that correspond one-to-one with six operation buttons C21 to C26. The six tact switches are configured to turn on when the corresponding operation buttons C21 to C26 are pressed. In other words, the input receiving unit 50 is configured to accept operation inputs corresponding to each operation button C21 to C26 when the tact switches are turned on.

[0056] The control unit 51 mainly consists of a microcontroller. The control unit 51 is configured to perform various processes related to lighting control, such as scene selection and switching the lighting device A1 on and off, by having the microcontroller's processor execute a control program.

[0057] The wireless communication unit 52, like the wireless communication unit 12 of the lighting device A1, includes a wireless communication circuit and an antenna. The wireless communication circuit is an integrated circuit configured to perform wireless communication and mesh communication in accordance with the same wireless communication standards as the wireless communication circuit of the wireless communication unit 12. The wireless communication circuit can send and receive wireless signals through the antenna. The wireless communication unit 52 transmits messages, including control commands received from the control unit 51, via wireless signals.

[0058] (2.2) Mesh networks in wireless communication systems The wireless communication system S1 constructs a mesh network in which each of the lighting device A1, sensor device B1, and communication device D1 acts as a communication terminal 100 (node). Each node in the mesh network (lighting device A1, sensor device B1, and communication device D1) is assigned a unique network address.

[0059] In this embodiment, the mesh network NW1 forms a partially connected mesh network, as shown in Figure 7. The mesh network NW1 has multiple (four in the illustrated example) subnetworks SN1, SN2, SN3, and SN4. Each of the multiple subnetworks SNi (i=1,2,3,4) has one or more nodes Nij (j=1,2,…). Each of the multiple nodes Nij can communicate directly with other nodes Nij within its own subnetwork SNi, but cannot communicate directly with nodes Nij belonging to a different subnetwork SNi.

[0060] In each subnetwork SNi, one of several nodes Nij acts as the management node MNi. Each management node MNi can communicate directly with other nodes Nij within its own subnetwork SNi, and also with other management nodes MNi belonging to other subnetwork SNi. In other words, all nodes Nij belonging to each subnetwork SNi can communicate via the management node MNi of its own subnetwork SNi with all nodes Nij belonging to other subnetwork SNi.

[0061] Furthermore, one of the multiple management nodes MNi acts as the master unit. The master unit performs processes such as synchronizing all nodes Nij (including the management node MNi) belonging to the mesh network NW1, and broadcasting messages to the entire mesh network NW1.

[0062] (2.3) Grouping in wireless communication systems As shown in Figure 8, a single wireless communication system S1 has one or more areas ARi (i=1,2,…,n). Each area ARi has one or more zones ZNij (j=1,2,…). Each zone ZNij contains multiple lighting devices A1 and, if necessary, one sensor device B1. Note that each zone ZNij may contain only one lighting device A1, and may not contain a sensor device B1.

[0063] Furthermore, the zoning of zone ZNij and area ARi is independent of the topology of the mesh network NW1. For example, multiple zone ZNij and area ARi may exist in one subnetwork SNi. Alternatively, multiple node Nij belonging to different subnetworks SNi may exist in one zone ZNij. Note that a single wireless communication system S1 has at most one communication device D1, but the communication device D1 does not belong to any area ARi or any zone ZNij.

[0064] In the wireless communication system S1, communication device D1 acts as the master unit in the mesh network NW1. If communication device D1 is not available, the wireless communication system S1 may also use either lighting device A1 or sensor device B1 to act as the master unit.

[0065] When the wireless communication system S1 is in operation, tablet C1 can communicate with the management node MNi in the mesh network NW1 via BLE communication. The wireless communication system S1 assigns the role of management node MNi to either sensor device B1, lighting device A1, or communication device D1. Furthermore, tablet C1 can communicate with all nodes (communication device D1, sensor device B1, lighting device A1) and handheld remote control C2 via BLE communication.

[0066] The handheld remote control C2 can perform mesh communication with the nodes of the mesh network NW1 (lighting device A1, sensor device B1, and communication device D1) only when transmitting control commands. Additionally, the handheld remote control C2 can perform BLE communication with the tablet C1.

[0067] (3) Wireless communication method Next, a wireless communication method according to the embodiment will be described with reference to Figures 9 and 10. The wireless communication method according to the embodiment is performed, for example, by the wireless communication system S1 according to the embodiment. However, the entity that performs the wireless communication method is not limited to the wireless communication system S1.

[0068] The wireless communication method according to the embodiment includes a calculation step ST3 and a wireless communication step ST5, as shown in Figure 9. In the calculation step ST3, a backoff time T1 is calculated based on a single identification piece of information when the power is started up. The single identification piece of information is the identification piece assigned to one communication terminal 100A from among a plurality of identification pieces of information assigned to each of the plurality of communication terminals 100. In the wireless communication step ST5, the first wireless signal to be transmitted after the power is started up is transmitted after the backoff time T1 has elapsed.

[0069] In the wireless communication method according to this embodiment, in calculation step ST3, a backoff time T1 is calculated based on a single identification piece of information assigned to a single communication terminal 100A, and in wireless communication step ST5, a wireless signal is transmitted after the backoff time T1 has elapsed. This makes it less likely for burst traffic to occur when the power is started up, and as a result, it is possible to suppress a decrease in the reliability of communication when the power is started up.

[0070] (3.1) Operation when the power is started First, the operation of the wireless communication system S1 during power-up will be explained with reference to Figure 9.

[0071] Figure 9 is a flowchart of a wireless communication method performed by the wireless communication system S1 according to the embodiment. The wireless communication method includes steps ST1 to ST5 shown in Figure 9. Note that the flowchart shown in Figure 9 is an example, and for example, one or more steps other than steps ST1 to ST5 shown in Figure 9 may be included.

[0072] The wireless communication method according to this embodiment will be described in detail below.

[0073] When AC power from an external power source P1 is supplied to multiple lighting devices A1, sensor devices B1, and communication devices D1 in the wireless communication system S1, each communication terminal 100A of the wireless communication system S1 is powered on (startup step ST1) and performs a read step ST2. More specifically, in the read step ST2, the calculation unit 141 of lighting device A1, which is a communication terminal 100A, reads out a piece of identification information from the storage unit 13.

[0074] Next, each communication terminal 100A of the wireless communication system S1 performs calculation step ST3. More specifically, in calculation step ST3, the calculation unit 141 of the lighting device A1, which is a communication terminal 100A, calculates the backoff time T1 based on a single identification piece read from the storage unit 13. Specifically, the calculation unit 141 calculates the backoff time T1 based on the last three digits of the MAC address included in the single identification piece. For example, if the last three digits of the MAC address fall within the second numerical range, the calculation unit 141 sets the backoff time T1 to 200 μs.

[0075] Furthermore, each communication terminal 100A of the wireless communication system S1 performs a standby step ST4. More specifically, the control unit 14 of the lighting device A1, which is a communication terminal 100A, determines in the standby step ST4 whether or not the backoff time T1 has elapsed. If the backoff time T1 has not elapsed (standby step ST4: No), it waits until the backoff time T1 has elapsed. On the other hand, if the backoff time T1 has elapsed (standby step ST4: Yes), the control unit 14 causes the wireless communication unit 12 to transmit a wireless signal (wireless communication step ST5).

[0076] (3.2) Normal operation Next, the operation of the wireless communication system S1 during normal operation after power-up will be explained with reference to Figure 10.

[0077] Each communication terminal 100A of the wireless communication system S1 performs the second standby step ST11. More specifically, the control unit 14 of the lighting device A1, which is a communication terminal 100A, determines in the second standby step ST11 whether or not the interval specified in the communication protocol has elapsed. If the interval has not elapsed (second standby step ST11: No), it waits until the interval has elapsed. On the other hand, if the interval has elapsed (second standby step ST11: Yes), the control unit 14 causes the wireless communication unit 12 to transmit a wireless signal (second wireless communication step ST12).

[0078] (3.3)Specific examples Next, an example of operation using three lighting devices A11, A12, and A13, which constitute a single communication terminal 100A, will be explained with reference to Figure 11. In Figure 11, different types of hatching are applied to each period T0 to T3 to make them easier to identify.

[0079] In Figure 11, "T0" represents the period during which initialization processing is performed when the power supply is started. That is, initialization processing is performed in each lighting device A11, A12, and A13 from the time t0 when the power supply is started until period T0 has elapsed. Also, "T1" in Figure 11 is the back-off time for each lighting device A11, A12, and A13, as described above. Furthermore, "T2" in Figure 11 is the period during which the wireless signal is transmitted. And "T3" in Figure 11 is the interval (transmission interval) when transmitting the second wireless signal.

[0080] In the example in Figure 11, the backoff times T11 of lighting device A11, T12 of lighting device A12, and T13 of lighting device A13 are different from each other. More specifically, the backoff time T13 of lighting device A13 is longer than the backoff time T11 of lighting device A11 and shorter than the backoff time T12 of lighting device A12.

[0081] As a result, in the example shown in Figure 11, lighting device A11, which has the shortest backoff time T11, transmits the first radio signal first, lighting device A13, which has the second shortest backoff time T13, transmits the first radio signal next, and lighting device A12, which has the longest backoff time T12, transmits the first radio signal last. Here, in the example shown in Figure 11, the period T2 of lighting device A11 and the period T2 of lighting device A13 overlap to some extent, but burst traffic is less likely to occur compared to the case where the periods T2 of all three lighting devices A11, A12, and A13 overlap. Therefore, in the example shown in Figure 11, it is possible to suppress the decrease in communication reliability when the power is started up.

[0082] Furthermore, since each lighting device A11, A12, and A13 transmits a second radio signal at the same interval after transmitting the first radio signal, it is possible to suppress a decrease in communication reliability even after the transmission of the first radio signal.

[0083] (4) Effects In the wireless communication system S1 according to this embodiment, the calculation unit 141 calculates a backoff time T1 based on a single identification piece of information assigned to a communication terminal 100A, and the wireless communication unit 12 transmits a wireless signal after the backoff time T1 has elapsed. This makes it less likely for burst traffic to occur when the power is started up, and as a result, it is possible to suppress a decrease in the reliability of communication when the power is started up.

[0084] Furthermore, in the wireless communication system S1 according to the embodiment, a second wireless signal is transmitted periodically, which is transmitted after the first wireless signal. This makes it possible to suppress a decrease in communication reliability when transmitting the second wireless signal.

[0085] Furthermore, in the wireless communication system S1 according to the embodiment, the backoff time T1 is a predetermined value in one numerical range that includes the input value among a plurality of numerical ranges, and the input value is at least a part of a single identification information. This makes it possible to easily set the backoff time T1. In particular, if the predetermined value is set as the maximum value in one numerical range, it becomes possible to set the longest backoff time T1 for each numerical range.

[0086] (5) Variant The embodiments described above are merely one of many embodiments of this disclosure. The embodiments described above can be modified in various ways depending on the design, etc., as long as the objectives of this disclosure are achieved. Furthermore, functions similar to those of the wireless communication system S1 according to the embodiments described above may be embodied in the wireless communication method, (computer) program, or non-temporary recording medium on which the program is stored. A program according to one embodiment is a program that causes one or more processors to execute the wireless communication method described above. Such a program makes it possible to suppress a decrease in communication reliability when the power is started up.

[0087] The following lists some modifications of the above-described embodiment. The modifications described below can be combined and applied as appropriate.

[0088] (5.1) Variation 1 In the embodiments described above, the wireless communication unit 12 periodically transmits a second radio signal that is transmitted after the first radio signal, which is the first radio signal transmitted after the power is started. In contrast, the wireless communication unit 12 may transmit the second radio signal repeatedly. In this specification, "transmitting repeatedly" means transmitting the second radio signal aperiodically. Specifically, the wireless communication unit 12 may, for example, transmit some of a plurality of second radio signals at a first interval and transmit the remainder at a second interval different from the first interval. Alternatively, the wireless communication unit 12 may, for example, transmit one or more second radio signals only during a predetermined period after the power is started.

[0089] Even in this case, it is possible to suppress the deterioration of communication reliability when transmitting the second radio signal.

[0090] (5.2) Variation 2 In the above embodiment, the calculation unit 141 calculates the backoff time T1 based on a single identification piece of information each time the power is started up. Alternatively, the backoff time T1 calculated by the calculation unit 141 at the time the power is first started up may be stored in the storage unit 13. That is, a single communication terminal 100A may further have a storage unit 13 that stores the backoff time T1 calculated by the calculation unit 141. In this case, when the power is started up, the wireless communication unit 12 transmits a wireless signal after the backoff time T1 stored in the storage unit 13 has elapsed. As a result, the calculation unit 141 does not need to calculate the backoff time T1 when the power is started up for the second time or later, thus reducing the processing load on the calculation unit 141.

[0091] (5.3) Modification 3 In the above-described embodiment, the calculation unit 141 sets a predetermined value in the numerical range that includes the input value among a plurality of numerical ranges as the backoff time T1. Alternatively, the calculation unit 141 may set an output value obtained by substituting the input value into a function that has the input value as an independent variable as the backoff time T1. That is, the backoff time T1 is an output value obtained by substituting the input value into a function that has the input value as an independent variable, and the input value may be at least a part of a single identification information.

[0092] Specifically, the backoff time T1 can be calculated based on a linear function such as equation (1).

[0093] [Mathematics 1] T1 = a × x + b ····(1) Furthermore, the backoff time T1 can also be calculated based on a sine function, for example, as shown in equation (2).

[0094] [Math 2] T1 = a × sin(x) + b ····(2) In equations (1) and (2), "x" is a value based on a single piece of identification information (for example, the last three digits of a MAC address), and "a" and "b" are constants.

[0095] Even in this case, it becomes easy to set the backoff time T1.

[0096] (5.4) Modification 4 In the above embodiment, one piece of identification information includes a MAC address. In contrast, one piece of identification information may include information about a lighting device A1 as a communication terminal 100A. Information about lighting device A1 may include, for example, the model number of lighting device A1, the output type of lighting device A1 (e.g., dimming, color adjustment), the fixture type of lighting device A1 (e.g., ceiling light), or whether or not lighting device A1 has a sensor. This makes it possible to calculate the backoff time T1 based on the information about lighting device A1.

[0097] (5.5) Other variations The following lists other modifications of the embodiments described above.

[0098] The entity executing the wireless communication system S1 or wireless communication method in this disclosure includes a computer system. The computer system mainly consists of a processor and memory as hardware. The processor executes a program recorded in the computer system's memory to realize the function of the entity executing the wireless communication system S1 or wireless communication method in this disclosure. The program may be pre-recorded in the computer system's memory, provided via a telecommunication line, or provided on a non-temporary recording medium such as a memory card, optical disk, or hard disk drive that is readable by the computer system. The processor of the computer system consists of one or more electronic circuits including semiconductor integrated circuits (ICs) or large-scale integrated circuits (LSIs). The integrated circuits referred to here, such as ICs or LSIs, are named differently depending on the degree of integration and include integrated circuits called system LSIs, VLSIs (Very Large Scale Integration), or ULSIs (Ultra Large Scale Integration). Furthermore, FPGAs (Field-Programmable Gate Arrays) that are programmed after the manufacture of the LSI, or logic devices that allow for the reconfiguration of junction relationships or circuit compartments within the LSI, can also be used as processors. Multiple electronic circuits may be integrated onto a single chip or distributed across multiple chips. Multiple chips may be integrated onto a single device or distributed across multiple devices. The computer system referred to here includes a microcontroller having one or more processors and one or more memories. Therefore, the microcontroller also consists of one or more electronic circuits, including semiconductor integrated circuits or large-scale integrated circuits.

[0099] Furthermore, it is not essential for the wireless communication system S1 to have multiple functions integrated into a single housing; the components of the wireless communication system S1 may be distributed across multiple housings.

[0100] Conversely, in the above-described embodiment, at least some of the functions of the wireless communication system S1, which are distributed across multiple devices, may be consolidated into a single housing. For example, some of the functions of the wireless communication system S1, which are distributed across the lighting device A1 and the sensor device B1, may be consolidated into a single housing.

[0101] In the above embodiment, one piece of identification information includes the MAC address of one communication terminal 100A (lighting device A1). In contrast, one piece of identification information may include a random variable instead of a MAC address. Even in this case, it is possible to suppress the decrease in communication reliability when the power is started up.

[0102] In the above embodiment, the lighting device A1 is a single communication terminal 100A, but for example, at least one of the sensor device B1 and the communication device D1 may be a single communication terminal 100A. If the sensor device B1 is a single communication terminal 100A, the sensor control unit 22 includes a calculation unit for calculating the backoff time T1. If the communication device D1 is a single communication terminal 100A, the schedule control unit 42 includes a calculation unit for calculating the backoff time T1.

[0103] (Appearance) This specification discloses the following aspects:

[0104] The wireless communication system (S1) according to the first embodiment comprises a plurality of communication terminals (100), including one communication terminal (100A). The one communication terminal (100A) has a calculation unit (141) and a wireless communication unit (12). The calculation unit (141) calculates a backoff time (T1) based on a single piece of identification information when the power is started up. The single piece of identification information is the identification information assigned to one communication terminal (100A) from among a plurality of identification pieces of identification information assigned to each of the plurality of communication terminals (100). The wireless communication unit (12) transmits the first wireless signal to be transmitted after the power is started up, after the backoff time (T1) has elapsed.

[0105] In this embodiment, the calculation unit (141) calculates a backoff time (T1) based on a single identification piece of information assigned to a communication terminal (100A), and the wireless communication unit (12) transmits a wireless signal after the backoff time (T1) has elapsed. This makes it less likely for burst traffic to occur when the power is started up, and as a result, it is possible to suppress a decrease in the reliability of communication when the power is started up.

[0106] In the wireless communication system (S1) according to the second embodiment, in the first embodiment, a communication terminal (100A) is capable of communicating using one or more communication protocols, including one communication protocol. The wireless communication unit (12) transmits the first wireless signal to be transmitted in communication using one communication protocol after a backoff time (T1) has elapsed since the power was started.

[0107] According to this embodiment, it is possible to suppress the deterioration of communication reliability in communication using a single communication protocol.

[0108] In the wireless communication system (S1) according to the third embodiment, in the first or second embodiment, the wireless communication unit (12) periodically transmits a second wireless signal which is transmitted after the first wireless signal which is the wireless signal.

[0109] According to this embodiment, it is also possible to suppress the decrease in communication reliability when transmitting the second radio signal.

[0110] In the wireless communication system (S1) according to the fourth embodiment, in the first or second embodiment, the wireless communication unit (12) repeatedly transmits a second wireless signal which is transmitted after the first wireless signal which is the wireless signal.

[0111] According to this embodiment, it is also possible to suppress the decrease in communication reliability when transmitting the second radio signal.

[0112] In the fifth aspect of the wireless communication system (S1), in any one of the first to fourth aspects, a communication terminal (100A) further has a storage unit (13). The storage unit (13) stores the backoff time (T1) calculated by the calculation unit (141). When the power is started, the wireless communication unit (12) transmits the wireless signal after the backoff time (T1) stored in the storage unit (13) has elapsed.

[0113] According to this embodiment, it is possible to reduce the processing load on the calculation unit (141).

[0114] In the wireless communication system (S1) according to the sixth embodiment, in any one of the first to fifth embodiments, the backoff time (T1) is a predetermined value in one of the numerical ranges that contains the input value. The input value is at least a part of a single identification piece of information.

[0115] According to this embodiment, the backoff time (T1) can be easily set.

[0116] In the wireless communication system (S1) according to the seventh embodiment, in the sixth embodiment, the predetermined value is the maximum value within a single numerical range.

[0117] According to this embodiment, it is possible to set the longest backoff time (T1) for each numerical range.

[0118] In the wireless communication system (S1) according to the eighth aspect, in any one of the first to fifth aspects, the backoff time (T1) is an output value obtained by substituting the input value into a function whose independent variable is the input value. The input value is at least a part of a single identification piece of information.

[0119] According to this embodiment, the backoff time (T1) can be easily set.

[0120] In the wireless communication system (S1) according to the ninth embodiment, in any one of the first to eighth embodiments, one piece of identification information includes information relating to a lighting device (A1) as a communication terminal (100A).

[0121] According to this embodiment, it is possible to calculate the backoff time (T1) based on information regarding the lighting device (A1).

[0122] The communication device (A1) according to the tenth embodiment is used as a communication terminal (100A) in any one of the wireless communication systems (S1) according to the first to ninth embodiments.

[0123] In this embodiment, the calculation unit (141) calculates a backoff time (T1) based on a single identification piece of information assigned to a communication terminal (100A), and the wireless communication unit (12) transmits a wireless signal after the backoff time (T1) has elapsed. This makes it less likely for burst traffic to occur when the power is started up, and as a result, it is possible to suppress a decrease in the reliability of communication when the power is started up.

[0124] The wireless communication method according to the eleventh embodiment includes a calculation step (ST3) and a wireless communication step (ST5). In the calculation step (ST3), a backoff time (T1) is calculated based on a single identification piece of information when the power supply is started. The single identification piece of information is the identification piece of information assigned to one communication terminal (100A) from among a plurality of identification pieces of information assigned to each of a plurality of communication terminals (100). In the wireless communication step (ST5), the first wireless signal to be transmitted after the power supply is started is transmitted after the backoff time (T1) has elapsed.

[0125] In this embodiment, in the calculation step (ST3), a backoff time (T1) is calculated based on a single identification piece of information assigned to a single communication terminal (100A), and in the wireless communication step (ST5), a wireless signal is transmitted after the backoff time (T1) has elapsed. This makes it less likely for burst traffic to occur when the power is started up, and as a result, it is possible to suppress the deterioration of communication reliability when the power is started up.

[0126] The program according to the twelfth embodiment is a program that causes one or more processors to execute the wireless communication method according to the eleventh embodiment.

[0127] According to this embodiment, it is possible to suppress the deterioration of communication reliability when the power supply is started up.

[0128] The configurations relating to the second to ninth aspects are not essential to the wireless communication system (S1) and can be omitted as appropriate. [Explanation of Symbols]

[0129] 12 Wireless Communication Section 13 Storage section 100 communication terminals 100A Single communication terminal 141 Calculation Section A1 Lighting device (communication device) S1 Wireless Communication System ST3 Calculation Step ST5 Wireless Communication Step T1 Backoff Time

Claims

1. Equipped with multiple communication terminals, including one communication terminal, The aforementioned first communication terminal is, A calculation unit that calculates the backoff time at the time of power-up based on one of the multiple identification pieces of information assigned to one of the multiple communication terminals, and The system includes a wireless communication unit that transmits the first wireless signal to be transmitted after the power supply has been started, after the backoff time has elapsed. Wireless communication system.

2. The aforementioned communication terminal is capable of communicating using one or more communication protocols, including one communication protocol. The wireless communication unit transmits the first wireless signal to be transmitted in communication using the first communication protocol after the power supply has been started, after the backoff time has elapsed. The wireless communication system according to claim 1.

3. The wireless communication unit periodically transmits a second wireless signal which is transmitted after the first wireless signal, which is the wireless signal. The wireless communication system according to claim 1.

4. The wireless communication unit repeatedly transmits a second wireless signal which is transmitted after the first wireless signal, which is the wireless signal. The wireless communication system according to claim 1.

5. The aforementioned communication terminal further includes a storage unit that stores the backoff time calculated by the calculation unit, The wireless communication unit transmits the wireless signal after the backoff time stored in the memory unit has elapsed when the power supply is started. A wireless communication system according to any one of claims 1 to 4.

6. The aforementioned backoff time is a predetermined value in one of several numerical ranges, which is the numerical range that contains the input value. The input value is at least a part of the identification information. A wireless communication system according to any one of claims 1 to 4.

7. The predetermined value is the maximum value within the aforementioned numerical range. The wireless communication system according to claim 6.

8. The aforementioned backoff time is an output value obtained by substituting the input value into a function whose independent variable is the input value. The input value is at least a part of the identification information. A wireless communication system according to any one of claims 1 to 4.

9. The aforementioned identification information includes information relating to the lighting device as the aforementioned communication terminal, A wireless communication system according to any one of claims 1 to 4.

10. A wireless communication system according to any one of claims 1 to 4, used as the one communication terminal, Communication device.

11. A calculation step in which, when the power is started up, the backoff time is calculated based on one identification piece, which is the identification piece assigned to one of the multiple identification pieces assigned to each of the multiple communication terminals, The wireless communication step includes transmitting the first wireless signal to be transmitted after the power supply has been started up, after the backoff time has elapsed. Wireless communication method.

12. A program for causing one or more processors to execute the wireless communication method described in claim 11.

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