Radio communication system, radio communication method, and radio communication program

Abstract

To suppress occurrence of a state where the number of communication channels cannot be sufficiently secured while using a common channel map for a plurality of slave devices.SOLUTION: A plurality of slave devices 30A, 30B, 40A and 40B is divided into two or more groups. A communication channel to be used for radio communications is determined respectively for the divided slave devices belonging to at least one group, a common communication channel is extracted from the determined communication channel, and a common channel map is created. A master device 20 and the slave device divided into at least one group execute radio communications via the communication channel selected from the common communication channel indicated by the common channel map.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present disclosure relates to a wireless communication system, a wireless communication method, and a wireless communication program in which at least one master device and multiple slave devices perform wireless communication via one communication channel selected sequentially from multiple communication channels. [Background technology]

[0002] As this type of wireless communication system, for example, the one described in Patent Document 1 is known. In the wireless communication system of Patent Document 1, when a packet error occurs in a signal received by a wireless communication device, if the RSSI value of the wireless signal of the packet is greater than a preset threshold Th1, the wireless communication device determines that the reception operation of receiving this packet is a reception error caused by interference with other radio waves. Then, the wireless communication device counts the number of receptions and the number of reception errors, and stores the frequency of reception errors caused by interference in each frequency channel (number of reception errors / number of receptions). When the reception error frequency exceeds a threshold Th2, the wireless communication device determines that an interference source exists in the frequency channel where the reception error frequency caused by interference exceeds the threshold Th2, and stores this frequency channel as an unavailable channel. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2006-128812 A Summary of the Invention [Problem to be solved by the invention]

[0004] As described above, the wireless communication system of Patent Document 1 sets a frequency channel whose communication quality has deteriorated due to interference with other radio waves as an unavailable channel. In addition, the wireless communication system of Patent Document 1 restores the frequency channel that has been set as an unavailable channel to an available frequency channel after a predetermined set period has elapsed. In the following, in this specification, creating a channel map showing available channels through control of setting a frequency channel as an unavailable channel or restoring it to an available channel is referred to as channel map control.

[0005] Here, when a master device performs wireless communication with multiple slave devices, it is possible to extract common communication channels from frequency channels (communication channels) available in each slave device and create a common channel map for each slave device. By creating such a common channel map, various processes related to the channel map, such as updating, saving, and transmitting the channel map, which are necessary for wireless communication with each of the multiple slave devices, can be easily performed. However, if a master device simply creates a common channel map for multiple slave devices with which it performs wireless communication, there is a risk that it will be difficult to secure a sufficient number of communication channels available for wireless communication, for example, when the number of communication channels common to each slave device is small.

[0006] The present disclosure has been made in consideration of the above-mentioned points, and aims to provide a wireless communication system, a wireless communication method, and a wireless communication program that are capable of suppressing the occurrence of a situation in which a sufficient number of communication channels cannot be secured while using a common channel map for multiple slave devices. [Means for solving the problem]

[0007] In order to achieve the above object, a wireless communication system according to the present disclosure is a wireless communication system in which at least one master device (20) and multiple slave devices (30) perform wireless communication via one communication channel sequentially selected from multiple communication channels, the wireless communication system comprising: a grouping unit (S50) for grouping a plurality of slave devices into two or more groups; a communication channel determination unit (S270, S280) for determining a communication quality of each communication channel for a slave device belonging to at least one group grouped by the grouping unit when the master device wirelessly communicates with each of the plurality of slave devices, and for determining a communication channel to be used for wireless communication based on a result of the determination of the communication quality of each communication channel; a creation unit (S290) that creates a common channel map by extracting a common communication channel that is a communication channel common to the slave devices belonging to at least one of the groups grouped by the grouping unit, based on the communication channel to be used for wireless communication determined by the communication channel determination unit; The master device and the slave devices grouped into at least one group are configured to perform wireless communication via a communication channel selected from the common communication channels indicated by the common channel map created by the creation unit.

[0008] A wireless communication method according to the present disclosure is a wireless communication method for performing wireless communication between at least one master device (20) and multiple slave devices (30) via one communication channel sequentially selected from multiple communication channels, the method comprising: Grouping a plurality of slave devices into two or more groups (S50); When the master device wirelessly communicates with each of the plurality of slave devices, the master device judges the communication quality of each communication channel for the slave devices belonging to at least one of the grouped groups, and determines the communication channel to be used for the wireless communication based on the judgment result of the communication quality of each communication channel (S270, S280); extracting a common communication channel that is a communication channel common to the slave devices belonging to at least one of the groups based on the communication channel to be used for wireless communication determined for the slave devices belonging to at least one of the grouped groups, and creating a common channel map (S290); The master device and the slave devices grouped into at least one group are configured to perform wireless communication via a communication channel selected from the common communication channels indicated by the created common channel map.

[0009] A wireless communication program according to the present disclosure is a wireless communication program for performing wireless communication between at least one master device (20) and multiple slave devices (30) via one communication channel sequentially selected from multiple communication channels, the program comprising: At least one processor has Grouping a plurality of slave devices into two or more groups (S50); When the master device wirelessly communicates with each of the plurality of slave devices, the master device judges the communication quality of each communication channel for the slave devices belonging to at least one of the grouped groups, and determines the communication channel to be used for the wireless communication based on the judgment result of the communication quality of each communication channel (S270, S280); extracting a common communication channel that is a communication channel common to the slave devices belonging to at least one of the groups based on the communication channel to be used for wireless communication determined for the slave devices belonging to at least one of the grouped groups, and creating a common channel map (S290); The master device and the slave devices grouped into at least one group are configured to perform wireless communication via a communication channel selected from the common communication channels indicated by the created common channel map.

[0010] As described above, in the wireless communication system, wireless communication method, and wireless communication program according to the present disclosure, a plurality of slave devices are grouped into two or more groups. Then, for the slave devices belonging to at least one of the grouped groups, a communication channel to be used for wireless communication is determined, and a common communication channel is extracted from the determined communication channels to create a common channel map. In this way, according to the wireless communication system, wireless communication method, and wireless communication program according to the present disclosure, a common channel map is not simply created for all slave devices, but a plurality of slave devices are grouped into two or more groups, and a common channel map is created for the slave devices belonging to at least one of the grouped groups. Therefore, it is possible to suppress the occurrence of a situation in which a sufficient number of communication channels cannot be secured for a plurality of slave devices while using a common channel map.

[0011] The reference numbers in parentheses above are merely an example of a correspondence with a specific configuration in an embodiment described below, in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure in any way.

[0012] In addition, the technical features described in each claim in addition to the features of the present disclosure described above will become apparent from the description of the embodiments described below and the accompanying drawings. [Brief description of the drawings]

[0013] [Figure 1] 1 is a block diagram showing an overall configuration, including a schematic configuration, of a wireless communication system according to a first embodiment. [Diagram 2] FIG. 4 is a diagram illustrating an example of the electric field strength distribution in a communication environment between a master device and a slave device. [Diagram 3] FIG. 4 is a diagram showing an example of received signal strength of each communication channel. [Figure 4] 10 is a flowchart showing an example of a start-up sequence of a master device and a slave device. [Diagram 5] 6 is a flowchart showing an example of a communication sequence between a master device and a slave device. [Figure 6] FIG. 13 is a diagram showing an example of a list held by a master device (or a control device) that associates identification information of a plurality of slave devices with information on the group to which each slave device belongs. [Figure 7] FIG. 13 is a diagram illustrating an example of the relationship between communication events and sub-events when the number of slave devices is two. [Figure 8] 6 is a flowchart showing an example of a channel map creation process in the flowchart of FIG. 5. [Figure 9] 13 is a table showing an example of a common channel map created for all slave devices when a master device communicates with a total of nine slave devices. [Figure 10] 13 is a table showing an example in which a total of nine slave devices are grouped into three groups, and a common channel map is created for each group. [Figure 11] 10 is a flowchart showing an example of a communication sequence in a wireless communication system according to a second embodiment. [Figure 12] FIG. 11 is an explanatory diagram for explaining a grouping technique in a wireless communication system according to a third embodiment. [Figure 13] FIG. 11 is a diagram showing an example in which a plurality of slave devices are grouped in accordance with a grouping technique in a wireless communication system according to a third embodiment. [Figure 14] FIG. 11 is a diagram showing another example in which a plurality of slave devices are grouped in accordance with a grouping technique in the wireless communication system according to the third embodiment. [Figure 15] FIG. 13 is a diagram showing an example in which a plurality of slave devices are grouped in accordance with a grouping technique in a wireless communication system according to a fourth embodiment. [Figure 16] FIG. 13 is a diagram showing an example in which a plurality of slave devices are grouped in accordance with a grouping technique in a wireless communication system according to a fifth embodiment. [Figure 17]FIG. 13 is a diagram showing another example in which a plurality of slave devices are grouped in accordance with a grouping technique in the wireless communication system according to the fifth embodiment. [Figure 18] FIG. 13 is a diagram illustrating a modified example of the wireless communication system according to the fifth embodiment. [Figure 19] FIG. 13 is a diagram showing another modified example of the wireless communication system according to the fifth embodiment. [Figure 20] FIG. 13 is a diagram showing yet another modified example of the wireless communication system according to the fifth embodiment. [Figure 21] 13 is a flowchart showing a grouping method in a wireless communication system according to a fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the drawings. Note that the same or similar configurations may be omitted from description by assigning the same reference number across multiple drawings. When only a portion of a configuration is described in each embodiment, the configuration of another embodiment described above may be applied to the other portion of the configuration. In addition to the combination of configurations explicitly stated in the description of each embodiment, configurations of multiple embodiments may be partially combined together even if not explicitly stated, as long as there is no particular problem with the combination.

[0015] (First embodiment) The wireless communication system according to the present embodiment includes at least one master device and multiple slave devices. At least one of the master device and the slave device may be mounted on a moving object for use. The moving object may include, for example, a vehicle such as an automobile or a railroad car, an aircraft such as an electric vertical take-off and landing aircraft or a drone, a ship, a construction machine, an agricultural machine, and the like.

[0016] 1 shows an example of a configuration in which a wireless communication system 10 according to the present embodiment is applied to a vehicle 100. As a specific application in the vehicle 100, the wireless communication system 10 according to the present embodiment can be applied to a variety of vehicle systems (vehicle applications). In this case, each of the multiple slave devices 30A, 30B, 40A, and 50A is associated with one of the multiple vehicle applications so as to perform wireless communication with the master device 20 to execute one of the applications among the multiple vehicle applications.

[0017] For example, the wireless communication system 10 can be applied as one of vehicle applications to a battery management system that manages batteries mounted as a battery pack in an electric vehicle, a hybrid vehicle, a plug-in hybrid vehicle, or the like. When the wireless communication system 10 is applied to a battery management system, for example, at least one master device 20 is connected to a control device 1 having a function as a battery control device, and multiple slave devices 30A, 30B are connected to first application devices 35A, 35B having a function as a monitoring device provided respectively for multiple battery stacks constituting a battery pack. In this case, both the master device 20 and the slave devices 30A, 30B are mounted on the vehicle.

[0018] The monitoring devices (first application devices 35A, 35B) provided in each battery stack acquire battery information such as the voltage and current of each battery cell included in the corresponding battery stack, the temperature of the battery stack, etc., using various sensors. Then, when the monitoring devices (first application devices 35A, 35B) receive data requesting battery information from the battery control device (control device 1) via the wireless communication system 10, they transmit the acquired battery information to the battery control device (control device 1) via the wireless communication system 10. Based on the acquired battery information, the battery control device (control device 1) calculates the state of charge (SOC) of the entire battery stack, drives a heating / cooling mechanism to adjust the temperature of the battery pack to an appropriate range, and determines whether or not to perform a so-called equalization process to equalize the voltages of each battery cell in the battery stack. When the battery control device (control device 1) determines that the equalization process needs to be performed in at least one battery stack, it instructs the corresponding monitoring device (first application devices 35A, 35B) to perform the equalization process via the wireless communication system 10. In addition, the monitoring device (first application device 35A, 35B) performs processing to determine abnormalities in various sensors and in its own operation, and if an abnormality is determined, transmits abnormality information to the battery control device (control device 1) via the wireless communication system 10.

[0019] The wireless communication system 10 according to the present embodiment can be applied to a smart key system (registered trademark, the same applies below) compatible with a so-called digital key or a tire pressure monitoring system as another vehicle application. When the wireless communication system 10 is applied to a smart key system compatible with a digital key, for example, the master device 20 is mounted on a vehicle and connected to a control device 1 having a function as a vehicle control device that controls locking and unlocking of a vehicle door and turning on and off a driving source such as a vehicle engine. The multiple slave devices are mounted on a mobile device (e.g., a smartphone or a smart watch) used as a digital key or an electronic key, none of which is shown in the figure, and are also arranged at various locations such as the front, side, and rear of the vehicle to detect the position of the digital key or electronic key relative to the vehicle 100. The multiple slave devices 40A arranged at various locations on the vehicle have a function of, for example, intercepting communication between the master device 20 and a slave device mounted on the digital key or electronic key and transmitting the intercepted communication result to the master device 20. As a result, the master device 20 (or the control device 1) can detect the position of the digital key or electronic key using positioning techniques such as multilateral surveying or polygonal surveying based on the position of each slave device 40A, the time when each slave device 40A intercepted the communication, and / or the angle of arrival of the communication signal at each slave device 40A.

[0020] When the wireless communication system 10 is applied to a tire pressure monitoring system, the master unit 20 is mounted on a vehicle and connected to a control unit 1 having a function as an air pressure monitoring control unit that displays the tire pressure and issues a warning when the air pressure is abnormal. The multiple slave units 50A are connected by wire or wirelessly to an air pressure detection device (third application device 55A) provided in each tire. The air pressure detected by the air pressure detection device (third application device 55A) is transmitted to the air pressure monitoring control unit (control unit 1) via the wireless communication system 10. The air pressure monitoring control unit (control unit 1) displays the tire pressure and issues a warning when the air pressure is abnormal based on the received air pressure.

[0021] Furthermore, the wireless communication system 10 according to the present embodiment may be applied to a vehicle diagnostic system instead of one of the above-mentioned vehicle applications or in addition to the vehicle applications. In this case, for example, a plurality of slave devices are connected to a plurality of vehicle-mounted devices (application devices) having a self-diagnosis function, and the master device is connected to a diagnostic control device installed in a service factory. In this example, a plurality of slave devices are mounted on the vehicle 100.

[0022] However, application examples of the wireless communication system 10 according to the present embodiment are not limited to vehicle applications, and as described above, the system can be applied to systems (applications) that control and manage various equipment of moving objects other than vehicles, such as aircraft such as drones, ships, construction machines, agricultural machines, etc. Furthermore, the wireless communication system 10 according to the present embodiment can be applied to systems that control and manage various equipment of buildings such as buildings, production facilities such as factories, etc.

[0023] In the following embodiment, an example will be described in which the wireless communication system 10 is applied to a battery management system, a smart key system, and a tire pressure monitoring system as multiple vehicle applications. In this case, as shown in FIG. 1, the master device 20 and slave devices 30A, 30B, 40A, and 50A of the wireless communication system 10 are all mounted on a vehicle (automobile) 100. There may be one master device 20 or multiple master devices 20. When multiple master devices 20 are provided, each of the multiple master devices 20 may communicate with multiple slave devices 30A, 30B, 40A, and 50A belonging to different groups. Alternatively, the multiple master devices 20 may communicate with multiple slave devices 30A, 30B, 40A, and 50A belonging to the same group. The master device 20 and slave devices 30A, 30B, 40A, and 50A communicate wirelessly via one communication channel that is sequentially selected from a number of communication channels, such as Bluetooth Low Energy (Bluetooth is a registered trademark, and hereinafter Bluetooth Low Energy will be abbreviated as Bluetooth LE) communication.

[0024] In the wireless communication between the master device 20 and the slave devices 30A, 30B, 40A, and 50A, a frequency band used in short-distance communication, such as the 2.4 GHz band or the 5 GHz band, can be used. Radio waves in such high-frequency bands tend to travel in a more directional manner than radio waves in the LF band, and tend to be reflected by metal objects such as the body of a vehicle. LF is an abbreviation for Low Frequency. For example, Bluetooth and Bluetooth LE can be adopted as standards for short-distance communication. As an example, the master device 20 and the slave devices 30A, 30B, 40A, and 50A of this embodiment are configured to be able to perform wireless communication conforming to the Bluetooth LE standard (hereinafter, Bluetooth LE communication). Details of the communication method related to the communication connection and encrypted communication are performed according to a sequence defined in the Bluetooth LE standard.

[0025] 1, the master device 20 includes a control circuit (CNT) 21, a wireless communication circuit (WC) 22, and an antenna 23. In addition to the above elements, the master device 20 may include an input / output interface and a bus line for wired or wireless communication with devices other than the slave devices 30A, 30B, 40A, and 50A. Note that processes such as a channel map control process, a channel map creation process, and a channel map sharing process, which will be described later, may be performed by the control circuit 21, or a part or all of these processes may be performed by another control device (e.g., the control device 1) provided outside the master device 20.

[0026] The control circuit 21 is, for example, a computer including a processor 211 and a memory 212. The memory 212 includes, for example, a RAM and a ROM. RAM is an abbreviation for Random Access Memory. ROM is an abbreviation for Read Only Memory.

[0027] In the control circuit 21, the processor 211 executes a predetermined process (control) by executing a program stored in the ROM while using the RAM as a temporary storage area. The processor 211 executes a plurality of instructions included in the program to construct a plurality of functional units. There may be a plurality of processors 211. The storage medium for the program is not limited to the ROM. For example, various storage media such as an HDD or SSD can be adopted. HDD is an abbreviation for Hard-disk Drive. SSD is an abbreviation for Solid State Drive.

[0028] The processor 211 is, for example, a CPU, an MPU, a GPU, or a DFP. CPU is an abbreviation for Central Processing Unit. MPU is an abbreviation for Micro-Processing Unit. GPU is an abbreviation for Graphics Processing Unit. DFP is an abbreviation for Data Flow Processor. The control circuit 21 may be realized by combining a plurality of types of arithmetic processing devices such as a CPU, an MPU, and a GPU. Alternatively, the control circuit 21 may be realized as an SoC. SoC is an abbreviation for System on Chip. The control circuit 21 may be realized using an ASIC or an FPGA. ASIC is an abbreviation for Application Specific Integrated Circuit. FPGA is an abbreviation for Field-Programmable Gate Array.

[0029] Control circuit 21 generates commands requesting processing from slave devices 30A, 30B, 40A, and 50A (e.g., commands requesting data, commands requesting execution of a predetermined process, etc.), and transmits transmission data including the commands in transmission packets to wireless communication circuit 22. Control circuit 21 also receives packets transmitted from slave devices 30A, 30B, 40A, and 50A via wireless communication circuit 22, and executes a predetermined process based on the data included in the received packets. In other words, the wireless communication between master device 20 and slave devices 30A, 30B, 40A, and 50A is packet communication.

[0030] The wireless communication circuit 22 includes an RF circuit (not shown) for wirelessly transmitting and receiving packets. The wireless communication circuit 22 has a transmission function of modulating a transmission signal and oscillating at the frequency of an RF signal. The wireless communication circuit 22 also has a reception function of demodulating a reception signal. RF is an abbreviation for radio frequency.

[0031] The wireless communication circuit 22 modulates a packet including the data transmitted from the control circuit 21 and transmits the modulated packet to the slave devices 30A, 30B, 40A, and 50A via the antenna 23. The control circuit 21 outputs to the wireless communication circuit 22 data obtained by encrypting the transmission data using, for example, encryption information exchanged in a connection establishment process described later. The wireless communication circuit 22 adds data necessary for wireless communication (for example, communication control information) to the transmission packet and transmits the packet. The data necessary for wireless communication includes, for example, an identifier (ID), a sequence number, a next sequence number, an error detection code, and the like. The wireless communication circuit 22 may control the data size, communication format, schedule, error detection, and the like of the communication between the master device 20 and the slave devices 30A, 30B, 40A, and 50A. The control circuit 21 may control these communications.

[0032] The wireless communication circuit 22 receives the packets transmitted from the slave devices 30A, 30B, 40A, and 50A via the antenna 23 and demodulates the packets. Then, the wireless communication circuit 22 transmits the demodulated packets to the control circuit 21. The antenna 23 converts the electrical signals into radio waves and radiates them into space. The antenna 23 receives the radio waves propagating through space and converts them into electrical signals.

[0033] The slave devices 30A, 30B, 40A, and 50A each have the same configuration. Below, the configuration and operation of the slave device 30A will be described as a representative example. However, multiple slave devices 30A, 30B, 40A, and 50A may be mentioned as necessary.

[0034] 1, the slave device 30A includes a control circuit (CNT) 31, a wireless communication circuit (WC) 32, and an antenna 33. In addition to the above-mentioned elements, the slave device 30A also includes an input / output interface and a bus line for wired or wireless communication with devices other than the master device 20. The control circuit 31 has a similar configuration to the control circuit 21 of the master device 20. The control circuit 31 includes, for example, a processor 311 and a memory 312. The memory 312 includes, for example, a RAM and a ROM.

[0035] The control circuit 31 executes the requested process (such as a response process of acquiring and returning the requested data, or an execution process of the requested process) based on the request command acquired via the wireless communication circuit 32. For example, if the request command included in the received data is a request to transmit battery information, the control circuit 31 of the slave device 30A transmits the transmission request to a monitoring device (such as the first application device 35A) of the corresponding battery stack, and acquires the battery information from the monitoring device (such as the first application device 35A). Then, in response to the request, the control circuit 31 transmits data encrypted using the encryption information, including the processing result (such as the acquired battery information), to the wireless communication circuit 32. The control circuit 31 can also execute control of a device mounted on a vehicle, for example, in accordance with the requested process.

[0036] The wireless communication circuit 32 includes an RF circuit (not shown) for wirelessly transmitting and receiving packets. The wireless communication circuit 32 has a transmitting function and a receiving function, similar to the wireless communication circuit 22. The wireless communication circuit 32 receives the packet transmitted from the master device 20 via the antenna 33 and demodulates it. Then, it transmits the data contained in the demodulated packet to the control circuit 31. The wireless communication circuit 32 modulates the packet containing the data transmitted from the control circuit 31 and transmits it to the master device 20 via the antenna 33. The wireless communication circuit 32 adds data necessary for wireless communication, such as communication control information, to the transmission packet and transmits it.

[0037] The wireless communication circuit 32 may control the data size, communication format, schedule, error detection, etc. of the communication between the master device 20 and the slave device 30A. The control circuit 31 may perform control related to these communications. The antenna 33 converts an electric signal into a radio wave and radiates it into space. The antenna 33 receives the radio wave propagating through space and converts it into an electric signal.

[0038] Fig. 2 is a diagram showing an example of an electric field strength distribution in a communication environment between the master device 20 and the slave device 30A. Fig. 2 shows the results of an electromagnetic field simulation at a specific timing at a specific frequency. Hereinafter, the electric field strength distribution may be referred to as the electric field distribution.

[0039] The master unit 20 and the slave unit 30A are disposed, for example, at predetermined positions in a vehicle. When the master unit 20 and the slave unit 30A, which are disposed at predetermined positions, transmit radio wave signals of a predetermined frequency, parts of high and low electric field strength are generated in the usage environment due to interference between the transmitted wave and the reflected wave and interference with external noise. The reflected wave is generated by reflection from metal elements of the vehicle present around the master unit 20 and the slave unit 30A, such as reflection from the vehicle body, reflection from a metal casing, and reflection from a harness. For this reason, the communication environment between the master unit 20 and the slave unit 30A has a plurality of so-called NULL points, which are parts of high electric field strength and parts of low electric field strength, as shown in FIG. 2.

[0040] If the slave device 30A is located in or near a portion of low electric field strength in the electric field distribution with the master device 20, the slave device 30A is more likely to be unable to correctly receive the wireless signal from the master device 20, which may result in a communication error. A communication channel with a high probability of such a communication error occurring is a communication channel with degraded communication quality.

[0041] When the master device 20 and the slave device 30A perform wireless communication via one communication channel selected in sequence from a plurality of communication channels, the frequency of each communication channel is different, and therefore the electric field distribution of each communication channel may also change, resulting in different communication quality for each communication channel.

[0042] For example, as shown in FIG. 3, in wireless communication via communication channel A, the received power (received signal strength), which is one of the parameters indicating the communication quality, is good. In addition, in wireless communication via communication channel C, the received power indicates a very high value. Therefore, when the master device 20 and the slave device 30A use communication channels A and C, which have good or very high communication quality, they can perform high-quality wireless communication in which communication errors are sufficiently suppressed. On the other hand, in wireless communication via communication channels B and N, the received power is low. Therefore, when the master device 20 and the slave device 30A use communication channels B and N, which have poor communication quality, there is a high possibility that a communication error will occur in the wireless communication. Note that in FIG. 3, for ease of understanding, an example of the received signal strength versus frequency is shown by a solid line.

[0043] Therefore, it is preferable that wireless communication between the master device 20 and the slave device 30A be performed using a communication channel that can perform high-quality wireless communication, avoiding communication channels with degraded communication quality.

[0044] However, the electric field distribution between the master device 20 and the slave device 30A changes depending on the external environment (such as external noise) and vibrations of the master device 20 and / or the slave device 30A (including vibrations of the metal housing and harness). Therefore, when the master device 20 and the slave device 30A are mounted on a vehicle, the electric field distribution of the communication environment between the master device 20 and the slave device 30A changes depending on, for example, the state of the vehicle (for example, running or stopped) and the state of the surrounding environment of the vehicle (for example, a lot or little external noise). As a result, the communication channels with good communication quality and the communication channels with deteriorated communication quality are not fixed but may change from moment to moment. Therefore, it is required to continuously monitor the communication quality of each communication channel, and, when the communication quality deteriorates, to delete the corresponding communication channel from the multiple communication channels used for wireless communication, and, when the communication quality recovers, to restore the corresponding communication channel as one of the multiple communication channels used for wireless communication.

[0045] In the wireless communication system 10 of the present embodiment, a control process for realizing wireless communication between the master device 20 and the slave device 30A using a communication channel with a certain communication quality, excluding a communication channel with a deteriorated communication quality due to channel map control, as a plurality of communication channels used for wireless communication will be described with reference to a diagram showing a communication sequence between the master device 20 and the slave device 30A shown in FIG. 5. In FIG. 5, the master device 20 is shown as MASTER, and the slave device 30A is shown as SLAVE. Note that FIG. 5 shows a communication sequence executed between the master device 20 and the slave device 30A. The master device 20 individually executes the communication sequence shown in FIG. 5 with the plurality of slave devices 30A, 30B, 40A, and 50A. However, the master device 20 can also transmit data to the plurality of slave devices 30A, 30B, 40A, and 50A simultaneously for each group. The groups will be described in detail later.

[0046] Here, the master device 20 and the slave device 30A execute a connection establishment process before executing the communication sequence shown in Fig. 5. Fig. 4 shows an example of a startup sequence including a connection establishment process that is executed from when the master device 20 and the slave device 30A start up until when they perform data communication. Note that the master device 20 also executes this connection establishment process individually with the multiple slave devices 30A, 30B, 40A, and 50A.

[0047] For example, when the wireless communication system 10 is mounted on a vehicle, a startup sequence is initiated when the IG signal is switched from off to on by a user operation. When the master device 20 and the slave device 30A are constantly connected, the startup sequence is performed only once at a predetermined timing. However, when an error occurs during communication and the wireless communication connection between the master device 20 and the slave device 30A is disconnected, the startup sequence may be performed to reconnect.

[0048] When the start-up sequence is started, the master device 20 and the slave device 30A execute a start-up process including an initialization process for initializing various variables, timers, etc., in steps S10 and S110, respectively. After that, the master device 20 and the slave device 30A execute a connection establishment process in steps S20 and S120, respectively. In the connection establishment process, for example, the slave device 30A executes an advertising operation to transmit an advertising signal through a communication channel for advertising, and the master device 20 executes a scanning operation to scan the advertising signal. The communication channel for advertising includes multiple communication channels (for example, three in the case of Bluetooth LE). When the master device 20 receives an advertising signal on any of the communication channels by the scanning operation, it transmits a connection request to the slave device 30A that transmitted the advertising signal. As a result, a communication connection is established between the master device 20 and the slave device 30A. When the master device 20 and the slave device 30A determine in steps S30 and S130, respectively, that a communication connection has been established, the master device 20 proceeds to step S40, and the slave device 30A proceeds to step S140.

[0049] The master device 20 and the slave device 30A exchange connection information in steps S40 and S140, respectively. In this exchange of connection information, the master device 20 and the slave device 30A exchange encryption information used for data communication and share initial information related to frequency channel hopping. The initial information includes, for example, an initial channel map, a hopping pattern, or a function for hopping. Furthermore, in the exchange of connection information, the master device 20 obtains identification information for identifying each of the slave devices 30A, 30B, 40A, and 50A from the slave device 30A. This identification information may be an identifier included in the communication control information, or may be identification information different from the identifier included in the communication control information.

[0050] The master device 20 (or the control device 1) holds a list that associates the identification information of each of the slave devices 30A, 30B, 40A, and 50A with information on the group to which each of the slave devices 30A, 30B, 40A, and 50A belongs. Fig. 6 shows an example of a list held by the master device 20 (or the control device 1) that associates the identification information of the slave devices 30A, 30B, 40A, and 50A with information on the group to which each of the slave devices 30A, 30B, 40A, and 50A belongs. As shown in Fig. 6, the list lists, for each group, the identification information of the slave devices 30A, 30B, 40A, and 50A belonging to each group.

[0051] In this embodiment, each group corresponds to each vehicle application. As described above, each of the slave devices 30A, 30B, 40A, and 50A is associated with one of the vehicle applications so as to perform wireless communication with the master device 20 to execute one of the vehicle applications. Therefore, in this embodiment, a list is defined so that each of the slave devices 30A, 30B, 40A, and 50A belongs to a group defined for the corresponding application. In step S50, the master device 20 (or the control device 1) refers to the list and groups the slave devices 30A based on the identification information wirelessly transmitted from the slave device 30A to the master device 20.

[0052] Alternatively, each of the slave devices 30A, 30B, 40A, and 50A may be configured to hold identification information for identifying the slave devices 30A, 30B, 40A, and 50A, and group information indicating the group to which each of the slave devices belongs. In this case, each of the slave devices 30A, 30B, 40A, and 50A transmits the identification information and group information it holds to the master device 20 when exchanging connection information for the startup sequence with the master device 20. The master device 20 can obtain information similar to the above-mentioned list from the identification information and group information transmitted from each of the slave devices 30A, 30B, 40A, and 50A. Therefore, the master device 20 (or the control device 1) can group the slave devices 30A, 30B, 40A, and 50A based on the received identification information and group information.

[0053] Next, in steps S60 and S150, the master device 20 and the slave device 30A perform data communication via a data communication channel selected by channel hopping from among the multiple communication channels available for communication shown in the channel map for each communication event that occurs periodically. The process for performing this data communication is shown in the communication sequence of FIG. 5. The master device 20 communicates with the multiple slave devices 30A, 30B, 40A, and 50A in order by allocating a communication period (sub-event) to each of the multiple slave devices 30A, 30B, 40A, and 50A in each communication event. The time chart of FIG. 7 shows an example of the relationship between communication events and sub-events when the number of slave devices is two. For example, in the example shown in the time chart of FIG. 7, the Master can transmit and receive data to and from Slave 1 during the period of sub-event 1 of each communication event, and can transmit and receive data to and from Slave 2 during the period of sub-event 2. Alternatively, the Master can transmit data to all Slaves 1 and 2 simultaneously during subevent 1 of each communication event, and data transmission from each Slave 1 and Slave 2 can be performed during subevent 1 and subevent 2, respectively.

[0054] When the master device 20 and the slave device 30A determine to disconnect the communication connection in steps S70 and S160, respectively, they end the startup sequence shown in Fig. 4. For example, when the wireless communication system 10 is mounted on a vehicle, the master device 20 and the slave device 30A may determine to disconnect the communication connection when the IG signal is switched from on to off by a user operation. The master device 20 and the slave device 30A may also determine to disconnect the communication connection when data communication cannot be performed normally a predetermined number of times in succession.

[0055] Next, a communication sequence of data communication will be described with reference to the flowchart of FIG. 5. As shown in FIG. 5, the master device 20 transmits, for example, a data request command to the slave device 30A in step S210. However, the master device 20 can also transmit, for example, a request to execute a predetermined process in addition to the data request. When the slave device 30A receives the data request in step S410, in step S420, the slave device 30A performs, for example, a checksum determination based on the error detection code included in the received data request to confirm whether the data request has been correctly received. If the slave device 30A determines in the process of step S420 based on the checksum determination result that the data request has not been correctly received, for example, in step S430, it transmits a signal indicating that the data request has not been correctly received or a signal requesting retransmission of the data request. On the other hand, if the slave device 30A determines in the process of step S420 that the data request has been correctly received, it performs, for example, a predetermined process required for responding, such as a process of acquiring and transmitting the requested data, in step S430.

[0056] The master device 20 and the slave device 30A switch the communication channel for data to be used by frequency channel hopping for each communication event, and transmit and receive a data request or requested data. At this time, the master device 20 and the slave device 30A determine the communication channel to be switched by frequency channel hopping according to the channel map that each device has. For example, in the case of Bluetooth LE communication, 37 communication channels are prepared as communication channels for data.

[0057] In step S220, the master device 20 receives the requested data. In step S230, the master device 20 performs, for example, a checksum check based on the error detection code included in the received data to confirm whether the data has been received correctly. In the following step S240, if the master device 20 determines in the process of step S230 that the data has not been received correctly, or if the master device 20 receives a signal from the slave device 30A indicating that the data request has not been received correctly, the master device 20 determines whether to perform a process for retransmission within the same communication event. For example, if there is enough time to perform retransmission before the end of the current communication event, the master device 20 can decide to perform retransmission, and if there is not enough time, the master device 20 can decide not to perform retransmission. In step S240, if the master device 20 determines to perform retransmission, it executes the process from step S210 again. If it is determined in the process of step S230 that the data has been received correctly, or if it is determined in step S240 that retransmission is not to be performed, the master device 20 proceeds to the process of step S250.

[0058] In step S250, the master device 20 transmits the received data to the control device 1, and the control device 1 executes processing based on information contained in the received data. Note that if the processing in step S230 determines that the data has not been received correctly, or if a signal indicating that the data request has not been received correctly is received from the slave device 30A, and if the processing in step S240 determines not to retransmit the data, the processing in step S250 may be omitted, or the processing in step S250 may be executed based on the previously received data.

[0059] In step S260, the master device 20 detects communication quality data indicating communication quality, such as received signal strength indicator (RSSI) and packet error rate (PER), as characteristic data indicating communication quality of the signal received from the slave device 30A. RSSI is an index indicating the strength of the signal transmitted from the slave device 30A and received by the master device 20. PER indicates the ratio of the number of error packets to the number of packets received by the master device 20, expressed as a percentage. The master device 20 may detect a signal-to-noise ratio (SNR) / signal-to-interference-to-noise ratio (SINR) instead of RSSI. For example, the SNR / SINR can be detected by the ratio between the RSSI value when the master device 20 receives a wireless signal from the slave device 30A and the RSSI value when the master device 20 does not receive a wireless signal. The master device 20 may also detect a bit error rate (BER) or a packet arrival rate (PAR) instead of PER. The master device 20 saves and accumulates the detected RSSI or SNR / SINR, PER, BER, or PAR for each communication channel. In addition to or instead of the master device 20 detecting the communication quality data as described above, the slave device 30A can also obtain the communication quality data by detecting the RSSI, PER, etc. when receiving a signal from the master device 20 and transmitting them to the master device 20.

[0060] In step S270, the master device 20 determines the degradation of the communication quality of the communication channel used for wireless communication with the slave device 30A based on the communication quality data of the communication channel detected in step S260. Then, the master device 20 deletes the communication channel whose communication quality is determined to be degraded from the communication channels used for wireless communication between the master device 20 and the slave device 30A. The communication channel to be deleted is a communication channel for data. For example, an example of a condition for determining the degradation of communication quality is that at least one of the RSSI and the PER does not satisfy the threshold value as a result of comparing the RSSI with the threshold value for RSSI and comparing the PER with the threshold value for PER. Note that the parameter to be compared with the threshold value may be one type. The parameter to be compared with the threshold value may be the parameter detected immediately before in step S260, or may be an average value of a predetermined number of parameters detected in multiple past wireless communications related to the same communication channel, or a median value thereof.

[0061] In step S280, the master device 20 executes a restoration determination of the communication channel deleted by the deletion determination at the time of the previous communication event. In this restoration determination, if a predetermined restoration condition is satisfied, the deleted communication channel is restored as a communication channel to be used for wireless communication. For example, as an example of the predetermined restoration condition, the deleted communication channel may be restored in response to a predetermined time having elapsed since the communication channel was deleted. Alternatively, as another example of the predetermined restoration condition, the deleted communication channel may be restored as a communication channel to be used for wireless communication in response to a communication channel adjacent to the deleted communication channel exhibiting good communication quality. In this way, the communication channel determined to be capable of restoration as a communication channel to be used for wireless communication is incorporated into the channel map and is actually used for wireless communication between the master device 20 and the slave device 30A. The deletion determination process in step S270 and the restoration determination process in step S280 correspond to the channel map control process in the present disclosure. Note that the communication channel determined to be restored may again be subject to deletion by the deletion determination if the communication quality when actually used for wireless communication remains deteriorated.

[0062] In step S290, the master device 20 performs a channel map creation process based on the deletion determination result in step S270 and the return determination result in step S280. This channel map creation process will be described in detail later.

[0063] Here, the channel map may indicate communication channels that can be used for wireless communication, or may indicate communication channels that cannot be used. Furthermore, the channel map may indicate both communication channels that can be used and communication channels that cannot be used. Furthermore, when the channel map is created and there is a change in the communication channels that can be used / unused, the frequency channel hopping pattern may be updated. When the frequency channel hopping pattern is not updated, for example, when the communication channel to be hopped is unavailable, the communication channel to be hopped next may be used.

[0064] The above-mentioned deletion determination process and return determination process may be performed each time communication is performed between the master device 20 and the slave device 30A. Alternatively, the deletion determination process and return determination process may be performed in accordance with the update period of the channel map, which is updated at a predetermined period, that is, collectively each time communication is performed between the master device 20 and the slave device 30A. In this case, each time communication is performed between the master device 20 and the slave device 30A, characteristic data indicating the communication quality of the communication channel used in the communication is detected and accumulated in step S260. Then, based on the accumulated characteristic data, for example, before the start of the channel map update period shown in the time chart of FIG. 7, the deletion determination in step S270 and the return determination in step S280 are performed collectively. Similarly, the channel map creation process in step S290 may also be performed each time communication is performed between the master device 20 and the slave device 30A. Alternatively, the channel map creation process may be performed in accordance with the channel map update period before the start of a new channel map update period, so that the channel map creation process can be transmitted to the slave device 30A during the new channel map update period.

[0065] In step S300, the master device 20 transmits the channel map created by the channel map creation process in step S290 to the slave device 30A. At this time, the master device 20 transmits information indicating the timing to start using the channel map together with the channel map. The timing to start using the channel map occurs every time a channel map update period has elapsed. In other words, the timing to start using the channel map is determined based on the channel map update period. Furthermore, as described later, the channel map created by the channel map creation process is also updated every time a channel map update period has elapsed.

[0066] In step S440, the slave device 30A receives the new channel map and timing information transmitted from the master device 20. When the slave device 30A receives the new channel map and timing information in step S440, in step S450, the slave device 30A performs a checksum check based on the error detection code included in the received packet to confirm whether the new channel map and timing information have been correctly received. If the slave device 30A determines in step S450 based on the checksum check result that the new channel map and timing information have not been correctly received, for example, in step S460, the slave device 30A does not transmit an acknowledgement signal (Ack signal) for the new channel map. On the other hand, if the slave device 30A determines in step S450 that the new channel map and timing information have been correctly received, the slave device 30A returns an acknowledgement signal (Ack signal) for the new channel map to the master device 20 in step S460.

[0067] In step S310, the master device 20 receives an Ack signal from the slave device 30A. In step S320, the master device 20 performs, for example, a checksum check based on the error detection code included in the received Ack signal to check whether the Ack signal has been received correctly. If the master device 20 does not receive the Ack signal itself, the checksum check results in NG. In the following step S330, the master device 20 determines whether to retransmit the new channel map and timing information within the same communication event, depending on whether the checksum check results in step S320 are OK or NG. More specifically, if the checksum check results in OK, or if the checksum check results in NG but there is not enough time to retransmit in the current communication event, the master device 20 determines not to retransmit within the same communication event, and ends the process shown in the flowchart of FIG. 5. On the other hand, if the checksum check results in NG and there is enough time to retransmit, the master device 20 returns to step S300 and retransmits the new channel map and timing information. In addition, if the checksum judgment result is OK and the sharing of the new channel map and timing information between the master device 20 and the slave device 30A is successful, the master device 20 does not need to transmit the new channel map and timing information in subsequent communication events until the channel map update period expires.

[0068] Next, the channel map creation process will be described with reference to the flowchart of Fig. 8. Fig. 8 is a flowchart showing an example of the channel map creation process executed by the master device 20 (or the control device 1).

[0069] Here, when the master device 20 performs wireless communication with multiple slave devices 30A, 30B, 40A, and 50A, it is possible to extract common communication channels from the communication channels available in each of the slave devices 30A, 30B, 40A, and 50A and create a common channel map for each of the slave devices 30A, 30B, 40A, and 50A. By creating such a common channel map, various processes related to the channel map, such as updating, saving, and transmitting the channel map, which are necessary for wireless communication with each of the multiple slave devices 30A, 30B, 40A, and 50A, can be easily performed. However, if the master device 20 simply creates a common channel map for the multiple slave devices 30A, 30B, 40A, and 50A with which it performs wireless communication, it may be difficult to secure a sufficient number of communication channels available for wireless communication, for example, when the number of communication channels common to each of the slave devices 30A, 30B, 40A, and 50A is small.

[0070] For example, the table in Fig. 9 shows an example in which three slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3 are associated with the vehicle application A, vehicle application B, and vehicle application C, respectively, and the master device 20 communicates with a total of nine slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3. In the table in Fig. 9, the communication channels available for wireless communication for each of the slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3 are indicated by "1," and the communication channels that cannot be used are indicated by "0." In addition, the common channel map shows the result of an AND operation between "1," which indicates the available communication channel of each of the slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3, and "0," which indicates the communication channel that cannot be used. That is, the common channel map indicates communication channels available to all slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3. As shown in the example of Fig. 9, if master device 20 simply created a common channel map for all slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3, there is a possibility that the number of common communication channels available for communication would be zero.

[0071] Therefore, in this embodiment, as described above, the multiple slave devices 30A, 30B, 40A, and 50A are grouped by vehicle application, and a common channel map is created for each group. As a result, for example, as shown in the table of Fig. 10, when three slave devices S_A1 to S_A3, S_B1 to S_B3, and S_C1 to S_C3 are associated with vehicle application A, vehicle application B, and vehicle application C, respectively, a common channel map for vehicle application A, a common channel map for vehicle application B, and a common channel map for vehicle application C are created. Since a common channel map is created for each group in this manner, each common channel map can secure a sufficient number of communication channels that can be used for communication.

[0072] Therefore, according to this embodiment, it is possible to prevent the occurrence of a situation in which a sufficient number of communication channels cannot be secured for the multiple slave devices 30A, 30B, 40A, and 50A while using a common channel map.

[0073] In the first step S510 of the flowchart in Fig. 8, the master device 20 determines whether or not it is time to create a common channel map for the slave device 30A with which it has performed communication. For example, the timing for creating the common channel map is set to the timing immediately before the start of a new channel map update period in the time chart in Fig. 7. This allows the created common channel map to be transmitted from the master device 20 to the slave device 30A during the new channel map update period, making it possible for the common channel map to be shared between the master device 20 and the slave device 30A.

[0074] The length and / or phase of the channel map update period may be different for at least two groups. When the length and / or phase of the channel map update period is different for at least two groups, the timing of creating the common channel map may also be different for each group.

[0075] In step S520, the master device 20 identifies a group for which a common channel map is to be created. For example, the master device 20 can identify a group to which the slave device 30A belongs based on the identification information and / or group information received from the slave device 30A with which wireless communication has been performed, thereby identifying the group for which a common channel map is to be created. In step S530, the master device 20 selects each of the slave devices 30A, 30B, 40A, and 50A belonging to the identified group by referring to a list, etc., and reads out channels available for communication of each of the selected slave devices 30A, 30B, 40A, and 50A. In step S540, the master device 20 extracts a common communication channel, which is a common communication channel, from the communication channels read out for each of the slave devices 30A, 30B, 40A, and 50A. Then, in step S550, the master device 20 creates a common channel map from the extracted common communication channels.

[0076] In this way, a new common channel map is created for each group every time a channel map update period elapses. The created common channel map is transmitted to the slave device 30A in step S300 of the above-mentioned flow chart of FIG. 5 at least until the common channel map is successfully shared in the channel map update period, which is the period during which the current common channel map is applied, as shown in the time chart of FIG. 7. Then, the master device 20 and the slave device 30A switch the common channel map to be used in the next update period to the successfully shared common channel map when a new channel map update period starts. As a result, as shown in the time chart of FIG. 7, in the next update period, wireless communication between the master device 20 and the slave device 30A is performed using the new successfully shared common channel map. In this way, by periodically updating the common channel map, the master device 20 and the slave device 30A can perform high-quality communication using a common channel map adapted to changes in the communication quality of each communication channel.

[0077] Second embodiment Next, a wireless communication system 10 according to a second embodiment of the present disclosure will be described with reference to the drawings. The wireless communication system 10 according to the present embodiment is configured similarly to the wireless communication system 10 according to the first embodiment, and therefore a description of the configuration will be omitted.

[0078] In the wireless communication system 10 according to the first embodiment described above, a plurality of slave devices 30A, 30B, 40A, and 50A are grouped for each vehicle application, and a common channel map is created for each group. However, the communication quality required may differ depending on the vehicle application. For example, in a tire pressure monitoring system, the change in the air pressure of the tire to be monitored over time is slight, so even if several communication errors occur in a short period of time in wireless communication by the wireless communication system 10, it does not become a big problem. Also, even if an entertainment system is constructed as a vehicle application, for example, by connecting a mobile device brought by a vehicle occupant to an in-vehicle system and reproducing music, video, and the like stored in the mobile device, the communication quality of the wireless communication does not need to be high because there is no direct effect on the control of the vehicle.

[0079] On the other hand, for example, the change in the state of the battery (for example, voltage, temperature, etc.) over time that is the subject of the battery management system is greater than the change in tire pressure over time, etc. Therefore, when the wireless communication system 10 is applied to a battery management system, it is desirable to prevent communication errors as much as possible.

[0080] Therefore, in this embodiment, the wireless communication system 10 is configured to exclude a group corresponding to a vehicle application from targets for updating the channel map at each update period in order to ensure communication quality, and to vary the criteria for determining the communication channel to be used for wireless communication. For example, by excluding slave devices belonging to one group from targets for updating the channel map, the processing load for executing channel map control in the master device 20 or the control device 1 can be reduced. Also, for example, by relaxing the criteria for deleting communication channels for vehicle applications that do not require strict communication quality, wireless communication can be performed using more communication channels.

[0081] The following describes the wireless communication system 10 according to the present embodiment, focusing on differences from the wireless communication system 10 according to the first embodiment. The wireless communication system 10 according to the present embodiment and the wireless communication system 10 according to the first embodiment differ mainly in the processing in the communication sequence.

[0082] Fig. 11 is a flowchart showing an example of a communication sequence of the wireless communication system 10 according to this embodiment. The flowchart in Fig. 11 includes a process of step S255 in addition to the flowchart in Fig. 5. Furthermore, the flowchart in Fig. 11 includes a process of step S275 instead of step S270 in the flowchart in Fig. 5.

[0083] In step S255, the master unit 20 determines whether the slave devices 30A, 30B, 40A, and 50A that have performed communication are slave devices that belong to a non-target group that is excluded from the channel map update target. If the slave devices belong to a non-target group, the master unit 20 does not perform the processes in and after step S260, and ends the communication sequence shown in the flowchart of FIG. 11. Therefore, for slave devices that belong to a non-target group, the determination of a communication channel to be used for wireless communication through the deletion of a communication channel and the restoration of a communication channel, and the creation of a common channel map in steps S275 and S280 are not performed. Slave devices that belong to a non-target group can continue to use the initial common channel map exchanged as part of the connection information in the startup sequence to communicate with the master unit 20.

[0084] In addition, whether or not to exclude each slave device belonging to a predetermined group from the channel map update target may be determined based on the communication quality of each slave device belonging to the predetermined group. For example, if the communication quality data of each slave device belonging to the predetermined group exceeds a predetermined standard, it can be determined that the quality of wireless communication between the master device 20 and each slave device belonging to the predetermined group is maintained good. In such a case, each slave device belonging to the predetermined group may be excluded from the target for updating the channel map. However, in this case, since it is necessary to obtain the communication quality data of each slave device, it is necessary to execute at least the process of step S260 in the flowchart of FIG. 11 and the process for determining the communication quality such as steps S275 and S280. Then, if any of the communication quality data of each slave device belonging to the predetermined group deteriorates, it may be returned to the channel map update target. Alternatively, at least one predetermined slave device belonging to the predetermined group may be excluded from the channel map update target. In this case, a common channel map for the predetermined group is created from the communication available channels of the remaining slave devices excluding the at least one predetermined slave device. In other words, the communication available channels of the at least one predetermined slave device are excluded from the calculation target for creating the common channel map. In this case, once a common channel map for a given group is created and updated, at least one given slave device also belongs to the given group and may therefore use the updated common channel map to perform wireless communication with master device 20.

[0085] In step S275, the master device 20 judges the deterioration of the communication quality of the communication channel used for wireless communication with the slave device 30A based on the communication quality data of the communication channel detected in step S260, similarly to step S270 of the flowchart in FIG. 5. Then, the master device 20 deletes the communication channel whose communication quality is judged to be deteriorated from the communication channels used for wireless communication between the master device 20 and the slave device 30A. However, in step S275, the master device 20 judges the deterioration of the communication quality based on a judgment criterion according to the group to which the slave device 30A with which the master device 20 communicates belongs. When high communication quality is required, the judgment criterion is set strict. For example, when the communication quality is judged based on RSSI, the threshold value as the judgment criterion is set relatively high, and when the communication quality is judged based on PER, the threshold value as the judgment criterion is set relatively low. Conversely, when a high communication quality is not required, the judgment criterion is relaxed. For example, when the communication quality is judged based on RSSI, the threshold value as the judgment criterion is set relatively low, and when the communication quality is judged based on PER, the threshold value as the judgment criterion is set relatively high. This makes it possible to determine whether or not a communication channel needs to be deleted depending on the level of communication quality required.

[0086] 11 only shows that the criteria for determining whether to delete a communication channel are determined according to the group to which the corresponding slave device belongs. However, the criteria for determining whether to restore a communication channel in step S280 may also be determined according to the group to which the corresponding slave device belongs. For example, when high communication quality is required, the waiting time until the deleted communication channel is restored may be set longer as the restoration determination criterion. Alternatively, when determining whether to restore a deleted communication channel based on the communication quality of an adjacent channel, restoration may be permitted when the communication quality of the adjacent channel meets a higher determination criterion.

[0087] Third embodiment Next, a wireless communication system 10 according to a third embodiment of the present disclosure will be described with reference to the drawings. The wireless communication system 10 according to the present embodiment is configured similarly to the wireless communication system 10 according to the first embodiment, and therefore a description of the configuration will be omitted.

[0088] In the wireless communication system 10 according to the first embodiment described above, the slave devices 30A, 30B, 40A, and 50A are grouped for each vehicle application. Fig. 12 shows an example of the arrangement of the slave devices S_A1 to S_A5, S_B1 to S_B4, and S_C1 in the vehicle 100, which are grouped for each vehicle application. In Fig. 12, the slave devices S_A1 to S_A5 are associated with a smart key system. The slave devices S_B1 to S_B4 are associated with a tire pressure monitoring system. In the example shown in Fig. 12, the slave device S_C1 of the mobile device carried by the occupant is grouped into one group.

[0089] When a group is formed for each vehicle application, the corresponding slave devices S_A1 to S_A5, S_B1 to S_B4, and S_C1 may be arranged over a wide area, as shown in Fig. 12. In this case, the communication environments (e.g., the effects of vibration and noise) of the individual slave devices S_A1 to S_A5, S_B1 to S_B4 belonging to the same group may differ. For this reason, when a group is formed for each vehicle application, if a slave device with a deteriorated communication environment is included, the number of communication channels included in the common channel map may be reduced due to the influence.

[0090] 13, in this embodiment, the slave devices S_A1-S_A2, S_B1-S_B2, S_C1-S_C2, S_D1-S_D2, S_E1, and S_F1 are grouped into a plurality of areas that are defined so as to include the positions of the slave devices S_A1-S_A2, S_B1-S_B2, S_C1-S_C2, S_D1-S_D2, S_E1, and S_F1 that perform wireless communication with the master device 20, based on the installation position of the master device 20. In the example shown in FIG. 13, six areas are defined so that the slave devices S_A1-S_A2, slave devices S_B1-S_B2, slave devices S_C1-S_C2, slave devices S_D1-S_D2, slave device S_E1, and slave device S_F1 each form a group.

[0091] In this way, by setting multiple areas based on the position of master device 20 and grouping the slave devices S_A1 to S_A2, S_B1 to S_B2, S_C1 to S_C2, S_D1 to S_D2, S_E1, and S_F1 contained in those areas, it is possible to group the slave devices S_A1 to S_A2, S_B1 to S_B2, S_C1 to S_C2, S_D1 to S_D2, S_E1, and S_F1 that have similar communication environments.

[0092] In this embodiment, the slave devices belonging to at least one of the grouped groups may be excluded from targets for updating the channel map in order to ensure communication quality. For example, when the communication quality data of the slave devices belonging to at least one of the grouped groups all exceed a predetermined standard, it can be determined that the quality of wireless communication between the master device 20 and the slave devices belonging to the corresponding group is maintained good. In such a case, the slave devices belonging to the corresponding group may be excluded from targets for updating the channel map. However, in this case, since it is necessary to obtain the communication quality data of each slave device, it is necessary to execute at least the process of step S260 in the flowchart of FIG. 11 and the processes for determining the communication quality such as steps S275 and S280.

[0093] Also, Fig. 13 shows an example in which a plurality of relatively small areas are defined around the master device 20 based on the installation position of the master device 20. However, the way in which the areas are defined is not limited to the example shown in Fig. 13. For example, as shown in Fig. 14, an in-vehicle area, an in-vehicle area, and an outside-vehicle area may be defined based on the installation position of the master device 20, and the slave devices S_A1, S_B1 to S_B8, and S_C1 included in each area may be grouped.

[0094] (Fourth embodiment) Next, a wireless communication system 10 according to a fourth embodiment of the present disclosure will be described with reference to the drawings. The wireless communication system 10 according to this embodiment is configured similarly to the wireless communication system 10 according to the first embodiment, and therefore a description of the configuration will be omitted.

[0095] In the wireless communication system 10 according to the third embodiment described above, a plurality of areas are defined and the slave devices belonging to each area are grouped based on the installation position of the master device 20. In contrast, in the wireless communication system 10 according to the present embodiment, the master device 20 is provided with a plurality of antennas, a plurality of areas are defined and the slave devices belonging to each area are grouped based on the installation positions of the plurality of antennas.

[0096] 15, the master device 20 has a plurality of antennas 23A-23E for wireless communication with a plurality of slave devices S_A1-S_A2, S_B1-S_B2, S_C1, S_D1-S_D2, and S_E1-S_E3. The plurality of antennas 23A-23E are installed at different positions on the vehicle 100. The plurality of slave devices S_A1-S_A2, S_B1-S_B2, S_C1, S_D1-S_D2, and S_E1-S_E3 are grouped into a plurality of areas that are defined based on the installation positions of the plurality of antennas 23A-23E so as to include the positions of the plurality of slave devices S_A1-S_A2, S_B1-S_B2, S_C1, S_D1-S_D2, and S_E1-S_E3 that perform wireless communication with the master device 20 in any one of the areas.

[0097] Therefore, in the wireless communication system 10 according to this embodiment, as in the third embodiment, the slave devices S_A1 to S_A2, S_B1 to S_B2, S_C1, S_D1 to S_D2, and S_E1 to S_E3 having similar communication environments can be grouped together.

[0098] Fifth embodiment Next, a wireless communication system 10 according to a fifth embodiment of the present disclosure will be described with reference to the drawings. The wireless communication system 10 according to this embodiment is configured similarly to the wireless communication system 10 according to the first embodiment, and therefore a description of the configuration will be omitted.

[0099] In the first embodiment described above, the slave devices associated with each vehicle application are grouped. In the third and fourth embodiments, a plurality of areas are defined based on the installation positions of the master device 20 or the plurality of antennas 23A to 23E, and the slave devices belonging to each area are grouped. However, the grouping method is not limited to the above-described method. For example, fixed slave devices installed at fixed positions and mobile slave devices that can be moved may be grouped into different groups.

[0100] Hereinafter, as the fifth embodiment, several examples in which the fixed slave devices and the mobile slave devices are grouped into different groups will be described.

[0101] FIG. 16 shows a wireless communication system 10 relating to a smart key system as an example of this embodiment. In the example shown in FIG. 16, the master device 20 and four slave devices S_A1 to S_A4 are installed at predetermined fixed positions in the vehicle 100. That is, the four slave devices S_A1 to S_A4 are fixed slave devices. One slave device S_B1 is mounted on an electronic key held by an occupant of the vehicle 100. That is, the one slave device S_B1 is a mobile slave device. Note that when multiple electronic keys are present within a range capable of communicating with the master device 20, the multiple slave devices mounted on the multiple electronic keys may be grouped into one group. Alternatively, the multiple slave devices mounted on the multiple electronic keys may be grouped into separate groups.

[0102] The communication environment of the fixed slave devices is considered to change less over time than the communication environment of the mobile slave devices. Therefore, as described above, by grouping the fixed slave devices and the mobile slave devices into different groups, it is possible to create and update a channel map suitable for each group.

[0103] FIG. 17 shows a wireless communication system 10 related to a battery management system as another example of this embodiment. In the example shown in FIG. 17, a vehicle 100 is equipped with three battery stacks A to C that constitute a battery pack. The three battery stacks A to C are housed in separate housings. The slave devices S_A1 to S_A3 are installed in the housings of the three battery stacks A to C, respectively. That is, the slave devices S_A1 to S_A3 are fixed slave devices. The master device 20 is installed in the housing of the battery stack A. The master device 20 has multiple antennas. The multiple antennas are installed inside the housing of the battery stack A, outside the housing of the battery stack A, inside the housing of the battery stack B, and inside the housing of the battery stack C. This allows the master device 20 to perform wireless communication with the slave devices S_A1 to S_A3 arranged in each housing under approximately the same conditions.

[0104] The battery management system uses a wireless device of a mobile device (e.g., a smartphone) carried by an occupant of the vehicle 100 as a slave unit S_B1. The mobile device has a function of receiving and displaying information about the battery state (e.g., charge level and temperature) through wireless communication between the master unit 20 and the slave unit S_B1. The slave unit S_B1 of the mobile device corresponds to a mobile slave unit.

[0105] As shown in Fig. 17, the slave devices S_A1 to S_A3, which are fixed slave devices, and the slave device S_B1, which is a mobile slave device, are grouped into different groups. This makes it possible to create and update a channel map suitable for each group, similar to the example shown in Fig. 16.

[0106] 16 and 17, the slave device S_B1, which is a mobile slave device, may be excluded from the targets for periodically updating the channel map. Furthermore, when the mobile slave device S_B1 performs wireless communication with the master device 20, the mobile slave device S_B1 may function as the master device and the master device 20 may function as the slave device.

[0107] Also, the configuration of the wireless communication system 10 related to the battery management system shown in FIG. 17 can be implemented with various modifications. For example, as shown in FIG. 18, the battery stacks A to C constituting the battery pack may be accommodated in a common housing instead of being accommodated in individual housings. Also, the wireless device 25 having the function of a master device arranged in the housing may be configured to also function as a slave device. In this case, the wireless device 25 is configured to act as a master device when performing wireless communication with the slave devices S_A1 to S_A3 arranged in the housing of the battery pack, and to act as a slave device when performing wireless communication with the master device 20 separately provided in the vehicle 100. That is, in this case, the wireless device 25 plays the role of a relay device in communication between the master device 20 and each of the slave devices S_A1 to S_A3 connected to the monitoring device of each battery stack accommodated in the housing.

[0108] 18, the master device 20 does not need to communicate individually with each of the slave devices S_A1 to S_A3 connected to the monitoring device of each battery pack, and can obtain information about the battery stack included in each battery pack and control the state of the battery stack by communicating only with the wireless device 25 acting as a relay device. Furthermore, when the battery performance of a battery pack deteriorates due to aging, the battery pack can be easily replaced.

[0109] Note that the communication between the wireless device 25 and each of the slave devices S_A1 to S_A3 in the battery pack may be wired communication instead of wireless communication, as shown in Fig. 19. In this case, the wireless device 25 only needs to have the function of a slave device that wirelessly communicates with the master device 20.

[0110] Alternatively, as shown in Fig. 20, a configuration may be adopted in which the wireless device of the mobile device functions as the master device, and wireless device 25 arranged inside the battery pack housing functions as the slave device. Furthermore, as described above, a wireless device of the mobile device, which is a mobile slave device, may function as the master device, and master device 20 may function as the slave device, with the wireless device of the mobile device communicating wirelessly with master device 20.

[0111] Sixth embodiment Next, a wireless communication system 10 according to a sixth embodiment of the present disclosure will be described with reference to the drawings. The wireless communication system 10 according to this embodiment is configured similarly to the wireless communication system 10 according to the first embodiment, and therefore a description of the configuration will be omitted.

[0112] In this embodiment, a method of grouping multiple slave devices 30A, 30B, 40A, and 50A into multiple groups will be described using a method different from that of each of the above-mentioned embodiments. The grouping method according to this embodiment does not group the slave devices 30A, 30B, 40A, and 50A into multiple groups in advance depending on the application, area, whether the slave devices are fixed or mobile, etc., but dynamically groups the multiple slave devices 30A, 30B, 40A, and 50A so that the number of common communication channels is equal to or greater than a predetermined threshold based on the communication channels used for wireless communication determined for each slave device 30A, 30B, 40A, and 50A. Therefore, in this embodiment, it can be said that slave devices with similar communication environments are grouped together based on the number of common communication channels. Note that the slave devices belonging to each group may or may not change over time. FIG. 21 is a flowchart showing the grouping method according to this embodiment.

[0113] In the first step S610, the master device 20 selects any one slave device (for example, slave device 30A) to be grouped. In step S620, the master device 20 determines whether or not one or more groups have already been formed. If no group has been formed in this determination process, the master device 20 proceeds to step S630. On the other hand, if one or more groups have been formed, the master device 20 proceeds to step S640.

[0114] In step S630, the master device 20 selects an arbitrary slave device (e.g., slave device 30B) other than the one slave device (e.g., slave device 30A) to be grouped, and sets one group including the selected slave device (e.g., slave device 30B).

[0115] In step S640, the master device 20 determines common communication channels when the slave device to be grouped (e.g., slave device 30A) is grouped into an existing group based on the communication channels of the selected slave device to be grouped (e.g., slave device 30A) and the common communication channels of the existing groups, and calculates the number of common communication channels. The common communication channels of a group mean communication channels common to the communication channels of all slave devices belonging to the group. If there are multiple existing groups, in step S640, the master device 20 determines common communication channels for all groups when the slave device to be grouped (e.g., slave device 30A) is grouped into an existing group, and calculates the number of common communication channels. Furthermore, if one group is set in step S630, in step S640, the master device 20 sets the communication channels of the slave device (e.g., slave device 30B) included in the set group as the common communication channels of the group.

[0116] In step S650, the master device 20 determines whether or not there is a group whose number of common communication channels calculated in step S640 is equal to or greater than a threshold. If there is no group whose number of common communication channels is equal to or greater than the threshold, the master device 20 proceeds to step S660. On the other hand, if there is a group whose number of common communication channels is equal to or greater than the threshold, the master device 20 proceeds to step S670.

[0117] In step S660, if the slave device to be grouped (e.g., slave device 30A) is grouped into an existing group, the number of common communication channels will decrease below the threshold, so the master device 20 sets a new group and groups the slave device to be grouped (e.g., slave device 30A) into the new group. Meanwhile, in step S670, the master device 20 determines whether there are multiple groups in which the number of common communication channels is equal to or greater than the threshold. If there is not multiple groups in which the number of common communication channels is equal to or greater than the threshold, that is, if there is only one group in which the number of common communication channels is equal to or greater than the threshold, the master device 20 proceeds to step S680. On the other hand, if there are multiple groups in which the number of common communication channels is equal to or greater than the threshold, the master device 20 proceeds to step S690.

[0118] In step S680, the master device 20 groups the slave devices to be grouped (e.g., slave device 30A) into groups in which the number of common communication channels is equal to or greater than the threshold. Meanwhile, in step S690, the master device 20 determines whether the number of common communication channels is the same for the multiple groups in which the number of common communication channels is equal to or greater than the threshold. If the numbers of common communication channels are different, the master device 20 proceeds to step S700. On the other hand, if the numbers of common communication channels are the same, the master device 20 proceeds to step S710.

[0119] In step S700, the master device 20 selects the group with the greater number of common communication channels, and groups the slave devices to be grouped (e.g., slave device 30A) into the selected group. On the other hand, in step S710, the master device 20 selects the group containing the smallest number of slave devices from among multiple groups that have the same number of common communication channels. If the numbers of slave devices are also the same, either group may be selected. In step S720, the master device 20 groups the slave devices to be grouped (e.g., slave device 30A) into the selected group.

[0120] In step S730, the master device 20 determines whether grouping of all slave devices is complete. If grouping of all slave devices is not complete, the master device 20 repeats the process from step S610. If grouping of all slave devices is complete, the master device 20 ends the grouping process shown in FIG.

[0121] In the sixth embodiment, slave devices belonging to at least one of the groups may be excluded from the channel map update. For example, if the number of common communication channels is equal to or greater than the exclusion threshold, the number of channels available for communication is large, and the communication quality of each slave device belonging to the group can be considered to be at a high level. In other words, it is possible to determine the level of communication quality of each slave device from the number of channels available for communication. In such a case, the slave devices belonging to the corresponding group may be excluded from the channel map update.

[0122] Although the above describes preferred embodiments of the present disclosure, the present disclosure is not limited to the above-described embodiments and can be modified in various ways without departing from the spirit and scope of the present disclosure.

[0123] For example, the features described in each of the above-mentioned embodiments can be implemented in combination with the features described in other embodiments, unless it is technically impossible to combine them.

[0124] Finally, this specification discloses the following technical ideas and combinations thereof. The combinations of the following technical ideas apply not only to the wireless communication system 10 but also to a wireless communication method and a wireless communication program.

[0125] (Technical thought 1) A wireless communication system in which at least one master device (20) and a plurality of slave devices (30) perform wireless communication via one communication channel sequentially selected from a plurality of communication channels, a grouping unit (S50) for grouping a plurality of the slave devices into two or more groups; a communication channel determination unit (S270, S280) that, when the master device wirelessly communicates with each of the plurality of slave devices, determines a communication quality of each communication channel for the slave devices that belong to at least one of the groups grouped by the grouping unit, and determines a communication channel to be used for wireless communication based on a result of the determination of the communication quality of each communication channel; a creation unit (S290) that extracts a common communication channel that is a communication channel common to the slave devices belonging to the at least one group based on the communication channel to be used for wireless communication determined by the communication channel determination unit for the slave devices belonging to the at least one group grouped by the grouping unit, and creates a common channel map; A wireless communication system in which the master device and the slave devices grouped into at least one group perform wireless communication via a communication channel selected from common communication channels indicated by a common channel map created by the creation unit.

[0126] (Technical thought 2) the creation unit periodically updates the common channel map by repeating creation of the common channel map over time; The wireless communication system described in Technical Idea 1, wherein the slave devices belonging to at least one other group than the at least one group grouped by the grouping unit are excluded from the targets for periodically updating the common channel map.

[0127] (Technical Thought 3) the slave devices each belonging to two or more groups grouped by the grouping unit are used as targets for determining a communication channel to be used in wireless communication by the communication channel determination unit; The wireless communication system according to Technical Idea 1, wherein the communication channel determination unit determines a communication channel to be used for wireless communication for each of the slave devices belonging to the two or more groups using different determination criteria for each group.

[0128] (Technical Thought 4) each of the plurality of slave devices is associated with one of the plurality of applications so as to perform wireless communication with the master device for execution of the application; The wireless communication system according to any one of Technical Ideas 1 to 3, wherein the grouping unit groups the slave devices associated with each of the plurality of applications for each of the plurality of applications.

[0129] (Technical Thought 5) The wireless communication system described in Technical Idea 1 or 2, wherein the grouping unit groups the multiple slave devices into multiple areas defined based on the installation position of the master device, the areas being defined so that any one of the areas includes the placement positions of the multiple slave devices that perform wireless communication with the master device.

[0130] (Technical Thought 6) The master device is mounted in a vehicle, The wireless communication system described in Technical Idea 5, wherein the multiple areas are divided into an in-vehicle area, an in-vehicle area, and an outside-vehicle area.

[0131] (Technical Thought 7) the master device has a plurality of antennas for wireless communication with the plurality of slave devices; The plurality of antennas are installed at different positions, The wireless communication system described in Technical Idea 1 or 2, wherein the grouping unit groups the multiple slave devices into multiple areas defined so that any one of the areas includes the placement positions of the multiple slave devices that perform wireless communication with the master device, based on the installation positions of the multiple antennas.

[0132] (Technical Thought 8) The plurality of slave devices include fixed slave devices that are installed at fixed positions and mobile slave devices that are movable, The wireless communication system according to any one of Technical Ideas 1 to 7, wherein the grouping unit groups the plurality of slave devices such that the fixed slave devices and the mobile slave devices are in different groups.

[0133] (Technical Thought 9) The wireless communication system according to Technical Idea 8, wherein the mobile slave devices grouped in a different group from the fixed slave devices are excluded from the targets of periodically updating a common channel map.

[0134] (Technical Thought 10) the mobile slave device is an electronic device carried by a user; The wireless communication system according to Technical Idea 8 or 9, wherein when the mobile slave device and the master device perform wireless communication, the mobile slave device functions as the master device and the master device functions as the slave device.

[0135] (Technical Thought 11) each of the plurality of slave devices has identification information for identifying the slave device, and transmits the identification information in wireless communication with the master device; the master device has a list in which the identification information is associated with information on a group to which the master device belongs; The wireless communication system according to any one of Technical Ideas 1 to 10, wherein the grouping unit groups the plurality of slave devices according to the list based on the identification information wirelessly transmitted from each of the plurality of slave devices to the master device.

[0136] (Technical Thought 12) each of the plurality of slave devices has identification information for identifying the respective slave devices and group information indicating a group to which the respective slave devices belong, and transmits the identification information and the group information in wireless communication with the master device; The wireless communication system according to any one of Technical Ideas 1 to 10, wherein the grouping unit groups the plurality of slave devices based on the identification information and the group information wirelessly transmitted from each of the plurality of slave devices to the master device.

[0137] (Technical Thought 13) The wireless communication system described in Technical Idea 1 or 2, wherein the grouping unit groups the multiple slave devices based on the communication channel to be used for wireless communication determined for each slave device by the communication channel determination unit so that the number of common communication channels is equal to or greater than a predetermined threshold.

[0138] (Technical Thought 14) The grouping unit determines a common communication channel when the slave devices to be grouped are grouped into at least one of the existing groups based on the communication channel used for wireless communication of the slave devices to be grouped and a common communication channel in at least one of the existing groups, and if the number of common communication channels determined is equal to or greater than the predetermined threshold, groups the slave devices to be grouped into the existing group, and if the number is less than the predetermined threshold, groups the slave devices to be grouped into a new group.

[0139] (Technical Thought 15) The grouping unit determines a common communication channel when the slave devices to be grouped are grouped into at least one of the existing groups based on the communication channel used for wireless communication of the slave devices to be grouped and a common communication channel in at least one of the existing groups, and if there are multiple existing groups in which the number of determined common communication channels is equal to or greater than the predetermined threshold, groups the slave devices to be grouped into the existing group in which the number of determined common communication channels is the largest.

[0140] (Technical Thought 16) The grouping unit determines a common communication channel when the slave devices to be grouped are grouped into at least one of the existing groups based on the communication channel used for wireless communication of the slave devices to be grouped and a common communication channel in at least one of the existing groups, and if there are multiple existing groups in which the number of determined common communication channels is equal to or greater than the predetermined threshold and the numbers of determined common communication channels are the same for the multiple existing groups, the grouping unit groups the slave devices to be grouped into the existing group containing the fewer slave devices. [Explanation of symbols]

[0141] 1: control device, 10: wireless communication system, 20: master device, 21: control circuit, 22: wireless communication circuit, 23: antenna, 30A, 30B, 40A, 50A: slave device, 31: control circuit, 32: wireless communication circuit, 33: antenna, 35A, 35B: first application device, 55A: third application device, 100: vehicle, 211: processor, 212: memory, 311: processor, 312: memory

Claims

1. A wireless communication system in which at least one master device (20) and a plurality of slave devices (30) perform wireless communication via one communication channel sequentially selected from a plurality of communication channels, A grouping unit (S50) that groups the plurality of slave devices into two or more groups; a communication channel determination unit (S270, S280) that, when the master device wirelessly communicates with each of the plurality of slave devices, determines a communication quality of each communication channel for the slave devices that belong to at least one of the groups grouped by the grouping unit, and determines a communication channel to be used for wireless communication based on a result of the determination of the communication quality of each communication channel; a creation unit (S290) that extracts a common communication channel that is a communication channel common to the slave devices belonging to the at least one group grouped by the grouping unit, based on the communication channel to be used for wireless communication determined by the communication channel determination unit, and creates a common channel map; A wireless communication system in which the master device and the slave devices grouped into at least one group perform wireless communication via a communication channel selected from common communication channels indicated by a common channel map created by the creation unit.

2. the creation unit periodically updates the common channel map by repeating creation of the common channel map over time; 2. The wireless communication system according to claim 1, wherein the slave devices that belong to at least one other group than the at least one group grouped by the grouping unit are excluded from being targets for periodically updating a common channel map.

3. the slave devices each belonging to two or more groups grouped by the grouping unit are used as targets for determining a communication channel to be used in wireless communication by the communication channel determination unit; The wireless communication system according to claim 1 , wherein the communication channel determination unit determines a communication channel to be used for wireless communication for the slave devices belonging to each of the two or more groups, using a different determination criterion for each group.

4. each of the plurality of slave devices is associated with one of the plurality of applications so as to perform wireless communication with the master device for execution of the application; The wireless communication system according to claim 1 , wherein the grouping unit groups the slave devices associated with each of the plurality of applications for each of the plurality of applications.

5. 3. The wireless communication system according to claim 1, wherein the grouping unit groups the slave devices into a plurality of areas defined based on an installation position of the master device, the plurality of areas being defined so that any one of the areas includes an arrangement position of the slave devices that perform wireless communication with the master device.

6. The master device is mounted in a vehicle, The wireless communication system according to claim 5 , wherein the plurality of areas are divided into an in-vehicle area, an interior vehicle area, and an exterior vehicle area.

7. the master device has a plurality of antennas for wireless communication with the plurality of slave devices; The plurality of antennas are installed at different positions, 3. The wireless communication system according to claim 1, wherein the grouping unit groups the slave devices into a plurality of areas defined based on installation positions of the antennas, the plurality of areas being defined so that any one of the areas includes an arrangement position of the slave devices that perform wireless communication with the master device.

8. The plurality of slave devices include fixed slave devices that are installed at fixed positions and mobile slave devices that are movable, 3. The wireless communication system according to claim 1, wherein the grouping unit groups the plurality of slave devices such that the fixed slave devices and the mobile slave devices are in different groups.

9. The wireless communication system according to claim 8 , wherein the mobile slave devices grouped in a different group from the fixed slave devices are excluded from being targets for periodically updating a common channel map.

10. the mobile slave device is an electronic device carried by a user; 9. The wireless communication system according to claim 8, wherein when the mobile slave device and the master device perform wireless communication, the mobile slave device functions as the master device, and the master device functions as the slave device.

11. each of the plurality of slave devices has identification information for identifying the slave device, and transmits the identification information in wireless communication with the master device; the master device has a list in which the identification information is associated with information on a group to which the master device belongs; The wireless communication system according to claim 1 , wherein the grouping unit groups the plurality of slave devices in accordance with the list based on the identification information wirelessly transmitted from each of the plurality of slave devices to the master device.

12. each of the plurality of slave devices has identification information for identifying the respective slave devices and group information indicating a group to which the respective slave devices belong, and transmits the identification information and the group information in wireless communication with the master device; The wireless communication system according to claim 1 , wherein the grouping unit groups the plurality of slave devices based on the identification information and the group information wirelessly transmitted from each of the plurality of slave devices to the master device.

13. 3. The wireless communication system according to claim 1, wherein the grouping unit groups the plurality of slave devices based on the communication channel to be used for wireless communication determined for each slave device by the communication channel determination unit so that the number of common communication channels is equal to or greater than a predetermined threshold.

14. 14. The wireless communication system according to claim 13, wherein the grouping unit determines a common communication channel when the slave devices to be grouped are grouped into at least one of the existing groups based on a communication channel used for wireless communication of the slave devices to be grouped and a common communication channel in at least one of the existing groups, and if the number of common communication channels determined is equal to or greater than the predetermined threshold, groups the slave devices to be grouped into the existing group, and if the number of common communication channels determined is less than the predetermined threshold, groups the slave devices to be grouped into a new group.

15. 14. The wireless communication system according to claim 13, wherein the grouping unit determines a common communication channel when the slave devices to be grouped are grouped into at least one of the existing groups based on a communication channel used for wireless communication of the slave devices to be grouped and a common communication channel in at least one of the existing groups, and when there are a plurality of the existing groups in which the number of determined common communication channels is equal to or greater than the predetermined threshold, groups the slave devices to be grouped into the existing group in which the number of determined common communication channels is the largest.

16. 14. The wireless communication system according to claim 13, wherein the grouping unit determines a common communication channel when the slave devices to be grouped are grouped into at least one of the existing groups based on a communication channel used for wireless communication of the slave devices to be grouped and a common communication channel in at least one of the existing groups, and if there are multiple existing groups in which the number of determined common communication channels is equal to or greater than the predetermined threshold and the numbers of determined common communication channels are the same for the multiple existing groups, the grouping unit groups the slave devices to be grouped into the existing group containing the fewer slave devices.

17. A wireless communication method for performing wireless communication between at least one master device (20) and multiple slave devices (30) via one communication channel sequentially selected from multiple communication channels, comprising: Grouping the slave devices into two or more groups (S50); When the master device wirelessly communicates with each of the plurality of slave devices, a communication quality of each communication channel is determined for the slave devices belonging to at least one of the grouped groups, and a communication channel to be used for wireless communication is determined based on a result of the determination of the communication quality of each communication channel (S270, S280); extracting a common communication channel that is a communication channel common to the slave devices belonging to the at least one group based on the communication channel to be used for wireless communication determined for the slave devices belonging to the at least one group, and creating a common channel map (S290); A wireless communication method in which the master device and the slave devices grouped into at least one group perform wireless communication via a communication channel selected from common communication channels indicated by a created common channel map.

18. A wireless communication program for performing wireless communication between at least one master device (20) and multiple slave devices (30) via one communication channel sequentially selected from multiple communication channels, comprising: At least one processor, Grouping the slave devices into two or more groups (S50); When the master device wirelessly communicates with each of the plurality of slave devices, a communication quality of each communication channel is determined for the slave devices belonging to at least one of the grouped groups, and a communication channel to be used for wireless communication is determined based on a result of the determination of the communication quality of each communication channel (S270, S280); extracting a common communication channel that is a communication channel common to the slave devices belonging to the at least one group based on the communication channel to be used for wireless communication determined for the slave devices belonging to the at least one group, and creating a common channel map (S290); A wireless communication program in which the master device and the slave devices grouped into at least one group perform wireless communication via a communication channel selected from common communication channels indicated by a created common channel map.

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