Wireless communication system, wireless communication method, and wireless communication program

Abstract

The plurality of slave devices (30A, 30B, 40A, 40B) are grouped into two or more groups. Then, for each of the slave devices belonging to the at least one grouped group, a communication channel for wireless communication is determined, a common communication channel is extracted from the determined communication channels, and a common channel map is generated. The master device (20) and the slave devices grouped into at least one group perform wireless communication via a communication channel selected from among common communication channels shown by a common channel map.

Description

Wireless communication systems, wireless communication methods and wireless communication programs

[0001] Citation of relevant applications

[0002] This application is based on Japanese Patent Application No. 2023-166448, filed on September 27, 2023, the contents of which are incorporated herein by reference in their entirety. Technical Field

[0003] This disclosure relates to a wireless communication system, wireless communication method, and wireless communication program, wherein at least one master device and a plurality of slave devices perform wireless communication via a communication channel selected sequentially from a plurality of communication channels. Background Technology

[0004] As a type of wireless communication system, the system described in Patent Document 1 is known, for example. In the wireless communication system of Patent Document 1, when a data packet error occurs in the received signal of the wireless communication device, if the RSSI value of the wireless signal of the data packet is greater than a preset threshold Th1, the wireless communication device determines that the receiving action of receiving the data packet is due to a receiving 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 frequency of reception errors exceeds the threshold Th2, the wireless communication device determines that there is an interference source in the frequency channel where the frequency of reception errors caused by interference exceeds the threshold Th2, and stores that frequency channel as an unusable channel.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2006-128812 Summary of the Invention

[0008] As described above, the wireless communication system of Patent Document 1 sets frequency channels whose communication quality degrades due to interference with other radio waves as unusable channels. Furthermore, after a predetermined setting period, the wireless communication system of Patent Document 1 restores the frequency channels set as unusable channels to usable frequency channels. Through this control of setting frequency channels as unusable channels or restoring them to usable channels, a channel mapping representing usable channels is generated; this will be referred to as channel mapping control in this specification.

[0009] Here, when a master device communicates wirelessly with multiple slave devices, it is advisable to extract shared communication channels from the available frequency channels (communication channels) of each slave device and generate a shared channel mapping for each slave device. This is because generating such a shared channel mapping simplifies various channel mapping-related processes required for individual wireless communication with multiple slave devices, such as updating, saving, and sending the channel mapping. However, if a shared channel mapping is simply generated for all slave devices communicating with the master device, it may be difficult to adequately ensure the number of communication channels available for wireless communication when the number of shared communication channels among the slave devices is small.

[0010] This disclosure is made in view of the above-mentioned problems, and aims to provide a wireless communication system, wireless communication method and wireless communication program that can use a shared channel mapping for multiple slave devices, while suppressing situations where the number of communication channels cannot be adequately guaranteed.

[0011] To achieve the above objectives, the wireless communication system disclosed herein is a wireless communication system that enables at least one master device and multiple slave devices to perform wireless communication via a communication channel sequentially selected from multiple communication channels. The system includes: a grouping unit that groups the multiple slave devices into two or more groups; a communication channel determination unit that, when the master device and the multiple slave devices are performing wireless communication, determines the communication quality of each communication channel for slave devices belonging to at least one group formed by the grouping unit, and determines a communication channel for wireless communication based on the determination result of the communication quality of each communication channel; and a generation unit that, for slave devices belonging to at least one group formed by the grouping unit, extracts a shared communication channel (i.e., a common communication channel) shared by the slave devices belonging to at least one group, based on the communication channel for wireless communication determined by the communication channel determination unit, and generates a shared channel mapping. 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 shared communication channel, which is shown by the shared channel mapping generated by the generation unit.

[0012] Furthermore, the wireless communication method disclosed herein is a wireless communication method for enabling at least one master device and multiple slave devices to perform wireless communication via a communication channel sequentially selected from multiple communication channels. The method includes the following steps: grouping the multiple slave devices into two or more groups; when the master device and the multiple slave devices are performing wireless communication respectively, for slave devices belonging to at least one group, determining the communication quality of each communication channel, and based on the determination result of the communication quality of each communication channel, determining the communication channel used for wireless communication; for slave devices belonging to at least one group, based on the determined communication channel used for wireless communication, extracting the communication channel shared by the slave devices belonging to at least one group, i.e., a shared communication channel, and generating a shared channel mapping. 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 shared communication channel, which is shown by the generated shared channel mapping.

[0013] Furthermore, the wireless communication program disclosed herein is a wireless communication program for enabling at least one master device and multiple slave devices to perform wireless communication via a communication channel sequentially selected from multiple communication channels. At least one processor performs the following actions: grouping the multiple slave devices into two or more groups; when the master device and the multiple slave devices are performing wireless communication respectively, for slave devices belonging to at least one group, determining the communication quality of each communication channel, and based on the determination result of the communication quality of each communication channel, determining the communication channel used for wireless communication; for slave devices belonging to at least one group, based on the determined communication channel used for wireless communication, extracting the communication channel shared by the slave devices belonging to at least one group, i.e., a common communication channel, and generating a common channel mapping. 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 channel, which is shown by the generated common channel mapping.

[0014] As described above, in the wireless communication system, wireless communication method, and wireless communication program of this disclosure, multiple slave devices are grouped into two or more groups. Then, for slave devices belonging to at least one of the grouped groups, a communication channel for wireless communication is determined, and a common communication channel is extracted from the determined communication channel to generate a common channel mapping. Thus, according to the wireless communication system, wireless communication method, and wireless communication program of this disclosure, the common channel mapping is not generated for all slave devices, but rather, after grouping multiple slave devices into two or more groups, a common channel mapping is generated for slave devices belonging to at least one of the grouped groups. Therefore, a common channel mapping can be used for multiple slave devices, while suppressing situations where the number of communication channels cannot be adequately guaranteed.

[0015] For ease of understanding of this disclosure, the reference numerals in parentheses within the claims are merely examples of correspondences with specific structures in the embodiments described later, and are not intended to limit the scope of this disclosure.

[0016] Furthermore, the technical features described in each of the claims, other than those of the present disclosure, can be clearly understood from the following description of the embodiments and the accompanying drawings. Attached Figure Description

[0017] Figure 1 is a block diagram showing the overall structure, including the schematic structure of the wireless communication system of the first embodiment.

[0018] Figure 2 is a diagram showing an example of the electric field intensity distribution in the communication environment between the master and slave devices.

[0019] Figure 3 is an example of the received signal strength of each communication channel.

[0020] Figure 4 is a flowchart illustrating an example of the start-up sequence of the master and slave devices.

[0021] Figure 5 is a flowchart illustrating an example of a communication sequence between a master device and a slave device.

[0022] Figure 6 is an example of a list held by the master device (or control device) that associates identification information of multiple slave devices with information about the group to which each slave device belongs.

[0023] Figure 7 is a diagram illustrating an example of the relationship between communication events and sub-events when the number of slave devices is two.

[0024] Figure 8 is a flowchart illustrating an example of the channel mapping generation process shown in Figure 5.

[0025] Figure 9 is a table illustrating an example of generating a shared channel mapping for all slave devices when the master device communicates with a total of nine slave devices.

[0026] Figure 10 is a table illustrating an example of grouping a total of nine slave devices into three groups and generating a shared channel mapping for each group.

[0027] Figure 11 is a flowchart illustrating an example of a communication sequence in a wireless communication system according to the second embodiment.

[0028] Figure 12 is an explanatory diagram illustrating the packet method of the wireless communication system according to the third embodiment.

[0029] Figure 13 is a diagram illustrating an example of grouping multiple slave devices according to a grouping method of a wireless communication system according to a third embodiment.

[0030] Figure 14 is a diagram illustrating another example of grouping multiple slave devices according to the grouping method of the wireless communication system according to the third embodiment.

[0031] Figure 15 is a diagram illustrating an example of grouping multiple slave devices according to a grouping method of a wireless communication system according to a fourth embodiment.

[0032] Figure 16 is a diagram illustrating an example of grouping multiple slave devices according to a grouping method of a wireless communication system according to a fifth embodiment.

[0033] Figure 17 is a diagram illustrating another example of grouping multiple slave devices according to the grouping method of the wireless communication system according to the fifth embodiment.

[0034] Figure 18 is a diagram illustrating a modified example of the wireless communication system according to the fifth embodiment.

[0035] Figure 19 is a diagram illustrating another variation of the wireless communication system according to the fifth embodiment.

[0036] Figure 20 is a diagram illustrating yet another variation of the wireless communication system according to the fifth embodiment.

[0037] Figure 21 is a flowchart illustrating the packet method of the wireless communication system according to the fourth embodiment. Detailed Implementation

[0038] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. Furthermore, for identical or similar structures, descriptions may be omitted in some cases by assigning the same reference numerals across multiple drawings. Where only a portion of the structure is described in each embodiment, structures from other previously described embodiments can be applied to the remaining portions of that structure. Moreover, not only combinations of structures explicitly described in the descriptions of each embodiment are possible, but structures from multiple embodiments can be partially combined with each other, even without explicit description, as long as they do not particularly hinder such combinations.

[0039] (First Implementation)

[0040] The wireless communication system of this embodiment includes at least one master device and multiple slave devices. At least one of the master device and slave devices can be mounted on a mobile body. Mobile bodies include, for example, vehicles such as automobiles and railway vehicles; flying bodies such as electric vertical take-off and landing aircraft and drones; ships; construction machinery; agricultural machinery, etc.

[0041] Figure 1 shows an example of the structure when the wireless communication system 10 of this embodiment is applied to a vehicle 100. As a specific application in the vehicle 100, the wireless communication system 10 of this embodiment can be applied to various and multiple vehicle systems (vehicle applications). In this case, each of the multiple slave devices 30A, 30B, 40A, and 50A corresponds to a specific application, each performing wireless communication with the master device 20 to execute one of the multiple vehicle applications.

[0042] For example, the wireless communication system 10 can be applied to a battery management system, which, as a vehicle application, manages the batteries installed in battery packs in electric vehicles such as electric cars, hybrid electric vehicles, and plug-in hybrid electric vehicles. 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 that functions as a battery control device, and multiple slave devices 30A and 30B are connected to first application devices 35A and 35B, respectively disposed in multiple battery stacks constituting the battery pack and functioning as monitoring devices. In this case, both the master device 20 and the slave devices 30A and 30B are installed in the vehicle.

[0043] Monitoring devices (first application devices 35A, 35B) installed in each battery stack acquire battery information such as the voltage and current of each individual battery cell and the temperature of the battery stack through 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 overall state of charge (SOC) of the battery stack, or drives the heating / cooling mechanism to adjust the temperature of the battery pack to an appropriate range, or determines whether a so-called equalization process to make the voltage of each individual battery cell in the battery stack consistent is required. If the battery control device (control device 1) determines that equalization processing 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 devices (first application devices 35A and 35B) process various sensor abnormalities and their own malfunctions, and when an abnormality is determined, they send abnormal information to the battery control device (control device 1) via the wireless communication system 10.

[0044] Furthermore, the wireless communication system 10 of this embodiment can be applied to smart key systems (registered trademark, hereinafter the same) corresponding to so-called digital keys, and tire pressure monitoring systems, which are used for other vehicle applications. When the wireless communication system 10 is applied to a smart key system corresponding to a digital key, for example, the master device 20 is installed in the vehicle and connected to a control device 1 that functions as a vehicle control device, controlling the locking / unlocking of vehicle doors and the opening / closing of the vehicle's engine and other drive sources. In addition to being installed in mobile devices (e.g., smartphones, smartwatches) and electronic keys used as digital keys (not shown), multiple slave devices are also disposed in various locations such as the front, sides, and rear of the vehicle to detect the position of the digital key and electronic key relative to the vehicle 100. The multiple slave devices 40A disposed in various locations of the vehicle have, for example, the following functions: monitoring the communication between the master device 20 and the slave devices installed in the digital key and electronic key, and sending the monitored communication results to the master device 20. Therefore, the master device 20 (or control device 1) can detect the position of the digital key and the electronic key using positioning technologies such as polygonal measurement and multi-angle measurement based on the position of each slave device 40A, the time of communication monitoring by each slave device 40A, and / or the arrival angle of the communication signal in each slave device 40A.

[0045] When the wireless communication system 10 is applied to the tire pressure monitoring system, the main device 20 is installed in the vehicle and connected to the control device 1, which functions as a tire pressure monitoring and control device, and displays tire pressure and issues warnings when pressure is abnormal. Multiple slave devices 50A are connected wired or wirelessly to tire pressure detection devices (third application device 55A) installed in each tire. The tire pressure detected by the tire pressure detection devices (third application device 55A) is transmitted to the tire pressure monitoring and control device (control device 1) via the wireless communication system 10. Based on the received tire pressure, the tire pressure monitoring and control device (control device 1) displays tire pressure and issues warnings when pressure is abnormal.

[0046] Furthermore, the wireless communication system 10 of this embodiment can also be applied to a vehicle diagnostic system, which replaces one of the aforementioned vehicle applications or adds a new one to the multiple vehicle applications. In this case, for example, multiple slave devices are connected to multiple on-board devices (application devices) with self-diagnostic functions, and the master device is connected to a diagnostic control device located in a service plant. In this example, multiple slave devices are installed in the vehicle 100.

[0047] However, the application examples of the wireless communication system 10 of this embodiment are not limited to vehicle applications. As described above, it can also be applied to systems (applications) that control and manage various equipment such as mobile bodies other than vehicles, such as drones, ships, construction machinery, and agricultural machinery. Furthermore, the wireless communication system 10 of this embodiment can also be applied to systems that control and manage various equipment in buildings such as buildings, production equipment in factories, etc.

[0048] Hereinafter, examples will be described of the wireless communication system 10 being applicable to battery management systems, smart key systems, and air pressure monitoring systems for multiple vehicle applications. In this case, as shown in FIG1, the master device 20 and slave devices 30A, 30B, 40A, and 50A of the wireless communication system 10 are all installed in a vehicle (automobile). There may be one or more master devices 20. When multiple master devices 20 are provided, each master device 20 may communicate with multiple slave devices 30A, 30B, 40A, and 50A belonging to different groups. Alternatively, multiple master devices 20 may communicate with multiple slave devices 30A, 30B, 40A, and 50A belonging to the same group. The master device 20 communicates with the slave devices 30A, 30B, 40A, and 50A, for example, via a communication channel selected sequentially from multiple communication channels, such as Bluetooth Low Energy (Bluetooth is a registered trademark; furthermore, Bluetooth Low Energy will be referred to as Bluetooth LE below).

[0049] In the wireless communication between the master device 20 and the slave devices 30A, 30B, 40A, and 50A, frequency bands used in short-range communication, such as the 2.4GHz band or the 5GHz band, can be used. Compared to LF band radio waves, such high-frequency radio waves have strong directness and are easily reflected by metallic objects such as vehicle bodies. LF is short for Low Frequency. Standards for short-range communication include, for example, Bluetooth and Bluetooth LE. As an example, the master device 20 and slave devices 30A, 30B, 40A, and 50A in this embodiment are configured to implement wireless communication conforming to the Bluetooth LE standard (hereinafter, Bluetooth LE communication). Details of the communication connection and encrypted communication methods are implemented according to the sequence specified in the Bluetooth LE standard.

[0050] As shown in Figure 1, the main device 20 includes a control circuit (CNT) 21, a wireless communication circuit (WC) 22, and an antenna 23. In addition to the above-mentioned elements, the main device 20 may also include input / output interfaces and bus lines for wired or wireless communication with devices other than slave devices 30A, 30B, 40A, and 50A. Furthermore, the channel mapping control processing, channel mapping generation processing, and channel mapping sharing processing, described later, can be implemented by the control circuit 21, or some or all of these processes can be implemented by other control devices located outside the main device 20 (e.g., control device 1).

[0051] The control circuit 21 is, for example, a computer including a processor 211 and a memory 212. The memory 212 includes, for example, RAM and ROM. RAM is short for Random Access Memory. ROM is short for Read Only Memory.

[0052] In the control circuit 21, the processor 211 uses RAM as a temporary storage area and executes a program stored in ROM to perform the prescribed processing (control). The processor 211 constructs multiple functional units by executing multiple instructions contained in the program. There can be multiple processors 211. The storage medium for the program is not limited to ROM. For example, various storage media such as HDD and SSD can be used. HDD is short for Hard-disk Drive. SSD is short for Solid State Drive.

[0053] Processor 211 can be, for example, a CPU, MPU, GPU, or DFP. CPU stands for Central Processing Unit. MPU stands for Micro-Processing Unit. GPU stands for Graphics Processing Unit. DFP stands for Data Flow Processor. Control circuit 21 can also be implemented by combining various types of computing devices such as CPU, MPU, and GPU. Alternatively, control circuit 21 can also be implemented as a SoC (System on Chip). SoC stands for System on Chip. Control circuit 21 can also be implemented using ASIC or FPGA. ASIC stands for Application Specific Integrated Circuit. FPGA stands for Field-Programmable Gate Array.

[0054] Control circuit 21 generates commands requesting processing from devices 30A, 30B, 40A, and 50A (e.g., commands requesting data, commands requesting the execution of specified processing, etc.), and transmits data containing these commands to wireless communication circuit 22 via data packets. Additionally, control circuit 21 receives data packets sent by slave devices 30A, 30B, 40A, and 50A via wireless communication circuit 22, and performs specified processing based on the data contained in the received data packets. In other words, the wireless communication between master device 20 and slave devices 30A, 30B, 40A, and 50A is data packet communication.

[0055] The wireless communication circuit 22 includes RF circuitry (not shown) for wirelessly transmitting and receiving data packets. The wireless communication circuit 22 has a transmission function that modulates the transmitted signal and oscillates at the frequency of the RF signal. Additionally, the wireless communication circuit 22 has a reception function that demodulates the received signal. RF is short for Radio Frequency.

[0056] Wireless communication circuit 22 modulates data packets containing data sent by control circuit 21 and transmits them to slave devices 30A, 30B, 40A, and 50A via antenna 23. Control circuit 21 outputs data to wireless communication circuit 22, for example, data encrypted using encryption information exchanged in the connection establishment process described later. Wireless communication circuit 22 appends data required for wireless communication (e.g., communication control information) to the transmitted data packets and transmits them. Data required for wireless communication includes, for example, identifiers (IDs), serial numbers, next serial numbers, error detection codes, etc. Wireless communication circuit 22 can control the data size, communication format, schedule, error detection, etc., of communication between master device 20 and slave devices 30A, 30B, 40A, and 50A. Control related to these communications can also be performed by control circuit 21.

[0057] Wireless communication circuit 22 receives and demodulates data packets transmitted by devices 30A, 30B, 40A, and 50A via antenna 23. Then, it transmits the demodulated data packets to control circuit 21. Antenna 23 converts electrical signals into radio waves and radiates them into space. Antenna 23 receives radio waves propagating in space and converts them into electrical signals.

[0058] Slave devices 30A, 30B, 40A, and 50A each have the same structure. Hereinafter, slave device 30A will be used as a representative example to explain its structure and operation. However, depending on the needs, multiple slave devices 30A, 30B, 40A, and 50A may be mentioned.

[0059] As shown in Figure 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 bus lines for wired or wireless communication with devices other than the master device 20. The control circuit 31 has the same structure as 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, RAM and ROM.

[0060] Based on the request command obtained via the wireless communication circuit 32, the control circuit 31 executes the requested processing (response processing such as acquiring and returning the requested data, execution processing of the requested processing, etc.). For example, when the request command contained in the received data is a request to send battery information, the control circuit 31 from the device 30A sends the sending request to the corresponding battery stack monitoring device (e.g., the first application device 35A) and acquires the battery information from the monitoring device (e.g., the first application device 35A). Then, in response to the request, the control circuit 31 sends data containing the processing result (e.g., the acquired battery information), encrypted with encryption information, to the wireless communication circuit 32. Alternatively, the control circuit 31 can also, for example, execute control of devices installed in the vehicle based on the requested processing.

[0061] Wireless communication circuit 32 includes RF circuitry (not shown) for wirelessly transmitting and receiving data packets. Like wireless communication circuit 22, wireless communication circuit 32 has both transmitting and receiving functions. Wireless communication circuit 32 receives and demodulates data packets transmitted by the main device 20 via antenna 33. Then, it transmits the data contained in the demodulated data packets to control circuit 31. Wireless communication circuit 32 modulates data packets containing data transmitted by control circuit 31 and transmits them to the main device 20 via antenna 33. Wireless communication circuit 32 appends communication control information and other data required for wireless communication to the transmitted data packets and transmits them.

[0062] The wireless communication circuit 32 can control the data size, communication format, schedule, and error detection of the communication between the master device 20 and the slave device 30A. Control related to this communication can also be performed by the control circuit 31. The antenna 33 converts electrical signals into radio waves and radiates them into space. The antenna 33 receives radio waves propagating in space and converts them into electrical signals.

[0063] Figure 2 is a diagram illustrating an example of the electric field intensity distribution in the communication environment between the master device 20 and the slave device 30A. Figure 2 shows the electromagnetic field simulation results at a specified time at a specified frequency. Hereinafter, the electric field intensity distribution will sometimes be referred to as the electric field distribution.

[0064] The master device 20 and slave device 30A are, for example, positioned at predetermined locations within a vehicle. When a radio wave signal of a predetermined frequency is transmitted from the master device 20 and slave device 30A, which are respectively positioned at predetermined locations, interference between the transmitted and reflected waves, as well as interference from external noise, creates portions of high and low electric field strength in the operating environment. The reflected waves are generated by reflections from metallic elements of the vehicle surrounding the master device 20 and slave device 30A, such as reflections from the vehicle body, metal casing, wiring harness, etc. For this reason, multiple portions of high electric field strength and so-called NULL points, which are portions of low electric field strength, are generated in the communication environment between the master device 20 and slave device 30A, as shown in Figure 2.

[0065] If the slave device 30A is located in or near a region of lower electric field strength in the electric field distribution relative to the master device 20, the likelihood of the slave device 30A failing to correctly receive wireless signals from the master device 20 increases, potentially leading to communication errors. Such communication channels, where communication errors are more likely to occur, are communication channels with degraded communication quality.

[0066] Here, when the master device 20 and the slave device 30A perform wireless communication via a communication channel selected sequentially from a plurality of communication channels, the electric field distribution of each communication channel may also change because the frequencies of each communication channel are different. As a result, the communication quality may differ in each communication channel.

[0067] For example, as shown in Figure 3, in wireless communication via communication channel A, the received power (received signal strength), one of the parameters representing communication quality, is good. Furthermore, in wireless communication via communication channel C, the received power exhibits a very high value. Therefore, when the master device 20 and slave device 30A utilize communication channels A and C, which have good or very high communication quality, high-quality wireless communication with sufficient suppression of communication errors can be performed. 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 slave device 30A utilize communication channels B and N, which have degraded communication quality, the possibility of communication errors occurring in wireless communication increases. Additionally, in Figure 3, for ease of understanding, a solid line represents an example of received signal strength relative to frequency.

[0068] Therefore, the wireless communication between the master device 20 and the slave device 30A preferably avoids communication channels that degrade communication quality and uses a communication channel that enables high-quality wireless communication.

[0069] However, the electric field distribution between the master device 20 and the slave device 30A varies depending on the external environment (such as external noise) and the vibration of the master device 20 and / or the slave device 30A (including vibration of the metal housing and wiring harness). Therefore, when the master device 20 and the slave device 30A are installed in a vehicle, the electric field distribution of the communication environment between the master device 20 and the slave device 30A varies, for example, depending on the vehicle's state (e.g., driving or stopped) and the state of the vehicle's surrounding environment (e.g., high or low external noise). As a result, communication channels with good communication quality and communication channels with degraded communication quality are not fixed and may change constantly. Therefore, it is necessary to continuously monitor the communication quality of each communication channel, delete the corresponding communication channel from the multiple communication channels used for wireless communication as the communication quality degrades, and restore the communication channel as one of the multiple communication channels used for wireless communication as the communication quality recovers.

[0070] In the wireless communication system 10 of this embodiment, multiple communication channels for wireless communication are used. Channel mapping control eliminates communication channels with degraded communication quality, and a communication channel ensuring a certain level of communication quality is used. This enables control processing for wireless communication between the master device 20 and the slave device 30A. The explanation will refer to the diagram in FIG5 showing the communication sequence between the master device 20 and the slave device 30A. In FIG5, the master device 20 is designated as the master device (MASTER), and the slave device 30A is designated as the slave device (SLAVE). FIG5 also shows the communication sequence executed between the master device 20 and the slave device 30A. The master device 20 implements the communication sequence shown in FIG5 with each of the multiple slave devices 30A, 30B, 40A, and 50A. However, the master device 20 may also transmit data simultaneously to each of the multiple slave devices 30A, 30B, 40A, and 50A in a group. The groups will be explained in detail later.

[0071] Here, the master device 20 and slave device 30A perform connection establishment processing before executing the communication sequence shown in FIG5. FIG4 shows an example of a startup sequence, including connection establishment processing, performed by the master device 20 and slave device 30A from startup to data communication. In addition, the master device 20 also performs this connection establishment processing with multiple slave devices 30A, 30B, 40A, and 50A respectively.

[0072] For example, when the wireless communication system 10 is installed in a vehicle, the startup sequence begins when the IG signal is switched from disconnected to connected by the user. Furthermore, if the master device 20 and slave device 30A are always connected, the startup sequence is executed only once at a predetermined time. However, if a communication error occurs and the wireless communication connection between the master device 20 and slave device 30A is severed, the startup sequence may be executed for reconnection.

[0073] When the startup sequence begins, the master device 20 and the slave device 30A perform startup processes in steps S10 and S110, respectively, which include initialization processes to initialize various variables, timers, etc. Then, the master device 20 and the slave device 30A perform connection establishment processes in steps S20 and S120, respectively. In the connection establishment process, for example, the slave device 30A performs a broadcasting action to send a broadcast signal via a broadcast communication channel, and the master device 20 performs a scanning action to scan for the broadcast signal. The broadcast communication channel includes multiple (e.g., three in the case of Bluetooth LE) communication channels. When the master device 20 receives a broadcast signal on any of the communication channels through the scanning action, it sends a connection request to the slave device 30A that sent the broadcast signal. Thus, 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.

[0074] In steps S40 and S140, the master device 20 and slave device 30A respectively exchange connection information. During this exchange, the master device 20 and slave device 30A exchange encrypted information used in data communication, or share initial information related to frequency channel hopping. The initial information may include, for example, an initial channel mapping, a frequency hopping mode, or a function used for frequency hopping. Furthermore, during the connection information exchange, the master device 20 obtains identification information from the slave device 30A for identifying each slave device 30A, 30B, 40A, and 50A. This identification information may be an identifier included in the communication control information, or it may be identification information different from the identifier included in the communication control information.

[0075] The master device 20 (or control device 1) holds a list that associates the identification information of each of the multiple slave devices 30A, 30B, 40A, and 50A with the information of the groups to which each of the slave devices 30A, 30B, 40A, and 50A belongs. Figure 6 shows an example of the list held by the master device 20 (or control device 1), which associates the identification information of the multiple slave devices 30A, 30B, 40A, and 50A with the information of the groups to which each slave device 30A, 30B, 40A, and 50A belongs. As shown in Figure 6, the list enumerates the identification information of the slave devices 30A, 30B, 40A, and 50A belonging to each group.

[0076] In this embodiment, each group corresponds to a vehicle application. As described above, each of the plurality of slave devices 30A, 30B, 40A, and 50A corresponds to a specific application by wirelessly communicating with the master device 20 to execute one of the plurality of vehicle applications. Therefore, in this embodiment, the plurality of slave devices 30A, 30B, 40A, and 50A are grouped according to the groups defined for their respective applications. In step S50, the master device 20 (or control device 1) refers to the list and groups the slave devices 30A based on the identification information wirelessly transmitted from the slave devices 30A to the master device 20.

[0077] Alternatively, each of the multiple slave devices 30A, 30B, 40A, and 50A may be configured to hold identification information for identifying each slave device 30A, 30B, 40A, and 50A and group information indicating the group to which each belongs. In this case, each of the multiple slave devices 30A, 30B, 40A, and 50A sends its held identification information and group information to the master device 20 during the exchange of connection information with the master device 20 during the startup sequence. The master device 20 can obtain the same information as the above list based on the identification information and group information sent by each of the multiple slave devices 30A, 30B, 40A, and 50A. Therefore, the master device 20 (or the control device 1) can group each slave device 30A, 30B, 40A, and 50A based on the received identification information and group information.

[0078] Next, in steps S60 and S150, the master device 20 and slave device 30A, respectively, perform data communication for each periodically occurring communication event via a data communication channel selected sequentially by channel switching from among the multiple communication channels available for communication as shown in the channel mapping. The processing for this data communication is shown in the communication sequence of FIG5. Furthermore, the master device 20 sequentially communicates with multiple slave devices 30A, 30B, 40A, and 50A by allocating communication periods (sub-events) to each communication event for each slave device 30A, 30B, 40A, and 50A. An example of the relationship between communication events and sub-events is shown in the timing diagram of FIG7 when there are two slave devices. For example, in the example shown in the timing diagram of FIG7, the master device can send and receive data with slave device 1 during sub-event 1 of each communication event, and send and receive data with slave device 2 during sub-event 2. Alternatively, the master device may simultaneously transmit data to all slave devices 1 and 2 during sub-event 1 of each communication event, while data transmissions from each slave device 1 and 2 are performed during sub-event 1 and sub-event 2, respectively.

[0079] When the master device 20 and slave device 30A determine that the communication connection is broken in steps S70 and S160 respectively, the startup sequence shown in FIG4 ends. For example, in the case where the wireless communication system 10 is installed in a vehicle, the master device 20 and slave device 30A may sometimes determine that the communication connection is broken when the IG signal is switched from on to off by the user's operation. In addition, the master device 20 and slave device 30A may sometimes determine that the communication connection is broken if they are unable to perform normal data communication for a specified number of consecutive times.

[0080] Next, referring to the flowchart in FIG5, the communication sequence of data communication will be described. As shown in FIG5, in step S210, the master device 20 sends a data request command to the slave device 30A, for example, that is, sends a data request. However, in addition to data requests, the master device 20 may also send requests to perform specified processing, for example. After receiving the data request in step S410, in step S420, the slave device 30 performs a checksum determination based on the error detection code contained in the received data request to confirm whether the data request can be received correctly. In the processing of step S420, if the slave device 30A determines that the data request cannot be received correctly based on the checksum determination result, for example in step S430, it sends a signal indicating that the data request cannot be received correctly, or a signal requesting retransmission of the data request. On the other hand, if the slave device 30A determines that the data request can be received correctly in the processing of step S420, in step S430, it performs the specified processing required for the response, such as the processing of obtaining the requested data and sending it.

[0081] Furthermore, for each communication event, the master device 20 and slave device 30A switch the communication channel used for data by performing frequency channel hopping to send and receive data requests and the requested data. At this time, the master device 20 and slave device 30A determine the communication channel switched by frequency channel hopping based on their respective channel mappings. For example, in the case of Bluetooth LE communication, 37 communication channels are prepared as data communication channels.

[0082] In step S220, the master device 20 receives the requested data. Then, in step S230, the master device 20 performs a checksum determination based on the error detection code contained in the received data to confirm whether the data can be received correctly. In the next step S240, if the master device 20 determines in step S230 that the data cannot be received correctly, or receives a signal from the slave device 30A indicating that the data request cannot be received correctly, it determines whether to perform the retransmission process within the same communication event. For example, if there is a time margin for retransmission before the end time of the current communication event, the master device 20 can decide to retransmit; if there is no margin, it can decide not to retransmit. In step S240, if the master device 20 decides to retransmit, it executes the process from step S210 again. If the master device 20 determines in step S230 that the data can be received correctly, or if it decides not to retransmit in step S240, the master device 20 proceeds to step S250.

[0083] In step S250, the master device 20 sends the received data to the control device 1, and the control device 1 performs processing based on the information contained in the received data. Alternatively, if in step S230 it is determined that data cannot be received correctly, or a signal indicating a data reception request failure is received from the slave device 30A, and in step S240 it is decided not to retransmit, step S250 can be omitted, or step S250 can be performed based on previously received data.

[0084] In step S260, the master device 20 detects communication quality data such as Received Signal Strength Index (RSSI) and Packet Error Rate (PER) to represent the communication quality of the signal received from the slave device 30A. RSSI is an indicator of the strength of the signal transmitted by the slave device 30A and received by the master device 20. PER is expressed as a percentage, representing the ratio of the number of erroneous packets to the number of packets received by the master device 20. The master device 20 may also detect Signal-to-Noise Ratio (SNR) / Signal-to-Interference-Noise Ratio (SINR) instead of RSSI. SNR / SINR can be detected, for example, by comparing the RSSI value when the master device 20 receives a wireless signal from the slave device 30A with the RSSI value when no wireless signal is received. Alternatively, the master device 20 may detect Bit Error Rate (BER) or Packet Arrival Rate (PAR) instead of PER. For each communication channel, the master device 20 stores and accumulates the detected RSSI or SNR / SINR, as well as PER, BER, or PAR. In addition, communication quality data can be obtained either by detecting RSSI, PER, etc. when receiving signals from the master device 20 as described above, or by having the slave device 30A detect these values ​​and send them to the master device 20.

[0085] In step S270, the master device 20 determines, based on the communication quality data of the communication channel detected in step S260, that the communication quality of the communication channel used for wireless communication with the slave device 30A has degraded. Then, the master device 20 removes the communication channel determined to have degraded communication quality from the communication channels used for wireless communication between the master device 20 and the slave device 30A. The deleted communication channel is a data communication channel. For example, one example of a condition for determining degraded communication quality is that the result of comparing RSSI with a threshold and comparing PER with a threshold is that at least one of RSSI and PER does not meet the threshold. Alternatively, the parameter compared with the threshold can be any one parameter. Furthermore, the parameter compared with the threshold can be the immediately adjacent parameter detected in step S260, or it can be the averaged value of a predetermined number of parameters detected in multiple previous wireless communications related to the same communication channel, or their median value.

[0086] In step S280, the master device 20 performs a recovery determination on the communication channel that was deleted due to the deletion determination during the previous communication event. In this recovery determination, if a predetermined recovery condition is met, the deleted communication channel is restored as a communication channel for wireless communication. For example, as one example of a predetermined recovery condition, the deleted communication channel can be restored after a predetermined time has elapsed since its deletion. Alternatively, as another example of a predetermined recovery condition, the deleted communication channel can be restored as a communication channel for wireless communication when the communication channel adjacent to the deleted communication channel exhibits good communication quality. In this way, the communication channel determined to be recoverable for wireless communication is programmed into a channel map and actually used for wireless communication between the master device 20 and the slave device 30A. The deletion determination process in step S270 and the recovery determination process in step S280 are equivalent to the channel mapping control process in this disclosure. Furthermore, if the communication quality of the communication channel still deteriorates when actually used for wireless communication after the recovery determination, it can be subject to deletion again through the deletion determination.

[0087] In step S290, the main device 20 performs channel mapping generation processing based on the deletion determination result of step S270 and the recovery determination result of step S280. This channel mapping generation processing will be described in detail later.

[0088] Here, channel mapping can represent communication channels that can be used for wireless communication, or communication channels that cannot be used. Furthermore, it can represent both available and unavailable communication channels. Additionally, by generating channel mapping, the frequency channel hopping pattern can be updated when the available / unavailable communication channels change. If the frequency channel hopping pattern is not updated, and the communication channel for the predetermined frequency hopping becomes unavailable, for example, the next predetermined frequency hopping communication channel can be used.

[0089] Furthermore, the aforementioned deletion and restoration determination processes can also be implemented each time communication occurs between the master device 20 and the slave device 30A. Alternatively, the deletion and restoration determination processes can be implemented uniformly in conjunction with the channel mapping update cycle, which is updated periodically according to a predetermined cycle, i.e., implemented uniformly whenever multiple communications occur between the master device 20 and the slave device 30A. In this case, each time communication occurs between the master device 20 and the slave device 30A, in step S260, characteristic data indicating the communication quality of the communication channel used in the communication is detected and accumulated. Then, based on the accumulated characteristic data, for example, before the start of the channel mapping update cycle shown in the timing diagram of FIG7, the deletion determination in step S270 and the restoration determination in step S280 are implemented centrally. Similarly, the channel mapping generation process in step S290 can also be implemented each time communication occurs between the master device 20 and the slave device 30A. Alternatively, the channel mapping generation process can also be implemented in conjunction with the channel mapping update cycle, before the start of a new channel mapping update cycle, and can be sent to the slave device 30A during the period of the new channel mapping update cycle.

[0090] In step S300, the master device 20 sends the channel map generated by the channel map generation process in step S290 to the slave device 30A. At this time, the master device 20 also sends information indicating the start time of use of the channel map along with the channel map. The start time of use of the channel map arrives each time a channel map update cycle elapses. The start time of use of the channel map is determined based on the channel map update cycle. Furthermore, as described later, the channel map generated by the channel map generation process is also updated each time a channel map update cycle elapses.

[0091] In step S440, the slave device 30A receives the new channel mapping and timing information sent by the master device 20. When the slave device 30A receives the new channel mapping and timing information in step S440, in step S450, a checksum is performed based on the error detection code contained in the received data packet to confirm whether the new channel mapping and timing information can be received correctly. If the slave device 30A determines in step S450 that the new channel mapping and timing information cannot be received correctly based on the checksum result, for example, in step S460, it does not send a new channel mapping reception acknowledgment signal (Ack signal). On the other hand, if the slave device 30A determines in step S455 that it can receive the new channel mapping and timing information correctly, it sends a new channel mapping reception acknowledgment signal (Ack signal) back to the master device 20 in step S460.

[0092] In step S310, the master device 20 receives an Ack signal from the slave device 30A. Then, in step S320, the master device 20 performs a checksum determination based on the error detection code contained in the received Ack signal, for example, to confirm whether the Ack signal can be received correctly. Furthermore, if the master device 20 cannot receive the Ack signal itself, the checksum determination result is NG. In the next step S330, the master device 20 determines whether to retransmit the new channel mapping and timing information within the same communication event based on whether the checksum determination result in step S320 is OK or NG. More specifically, if the checksum determination result is OK, or if the checksum determination result is NG but there is no time margin for retransmission 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 FIG5. On the other hand, if the checksum determination result is NG and there is a time margin for retransmission, the master device 20 returns to step S300 and retransmits the new channel mapping and timing information. In addition, if the checksum result is OK and the sharing of new channel mapping and timing information between the master device 20 and the slave device 30A is successful, the master device 20 may also not send new channel mapping and timing information in subsequent communication events after the channel mapping update cycle expires.

[0093] Next, the channel mapping generation process will be described with reference to the flowchart in Figure 8. Figure 8 is a flowchart showing an example of the channel mapping generation process performed by the main device 20 (or control device 1).

[0094] Here, when the master device 20 communicates wirelessly with multiple slave devices 30A, 30B, 40A, and 50A, it is possible to extract shared communication channels from the available communication channels of each slave device 30A, 30B, 40A, and 50A, and generate a shared channel mapping for each slave device 30A, 30B, 40A, and 50A. This is because generating such a shared channel mapping simplifies various channel mapping-related processes, such as updating, saving, and sending channel mappings, required for individual wireless communication with each slave device 30A, 30B, 40A, and 50A. However, if a shared channel mapping is simply generated for all slave devices 30A, 30B, 40A, and 50A that the master device 20 communicates with, it may be difficult to ensure a sufficient number of communication channels available for wireless communication when the number of shared communication channels among the slave devices 30A, 30B, 40A, and 50A is small.

[0095] For example, the table in Figure 9 shows an example of three slave devices S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3 corresponding to vehicle application A, vehicle application B, and vehicle application C, respectively, with the master device 20 communicating with a total of nine slave devices S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3. In the table of Figure 9, each slave device S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3 uses "1" to represent a communication channel that can be used for wireless communication and "0" to represent a communication channel that cannot be used. Furthermore, regarding the shared channel mapping, the result of a logical AND operation is shown, representing the "1" of the available communication channel and the "0" of the unavailable communication channel for each slave device S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3. That is, the shared channel mapping represents the communication channels available in all slave devices S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3. As shown in the example of Figure 9, if the master device 20 simply generates a shared channel mapping for all slave devices S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3 as objects, then the number of shared communication channels available for communication may be zero.

[0096] Therefore, in this embodiment, as described above, multiple slave devices 30A, 30B, 40A, and 50A are grouped according to each vehicle application, and a shared channel mapping is generated for each group. Thus, for example, as shown in the table of FIG10, when the three slave devices S_A1~S_A3, S_B1~S_B3, and S_C1~S_C3 correspond to vehicle application A, vehicle application B, and vehicle application C respectively, a shared channel mapping for vehicle application A, a shared channel mapping for vehicle application B, and a shared channel mapping for vehicle application C are generated. Because the shared channel mapping is generated for each group in this way, each shared channel mapping ensures a sufficient number of communication channels available for communication.

[0097] Therefore, according to this embodiment, a shared channel mapping can be used for multiple slave devices 30A, 30B, 40A, and 50A, while suppressing situations where the number of communication channels cannot be adequately guaranteed.

[0098] In the initial step S510 of the flowchart in Figure 8, the master device 20 determines whether it is the time for the shared channel mapping to be generated by the slave device 30A, with whom it is communicating. For example, in the timing diagram of Figure 7, the time for the shared channel mapping to be generated is set to a moment slightly before the start of a new channel mapping update cycle. Thus, the generated shared channel mapping is sent from the master device 20 to the slave device 30A during the new channel mapping update cycle, enabling it to be shared between the master device 20 and the slave device 30A.

[0099] Furthermore, the length and / or phase of the channel mapping update period can differ in at least two groups. In at least two groups, when the length and / or phase of the channel mapping update period differ, the shared channel mapping generation time may also differ for each group.

[0100] In step S520, the master device 20 determines the group to which the shared channel mapping is generated. For example, the master device 20 can determine the group to which the slave device 30A belongs based on identification information and / or group information received from the slave device 30A that is conducting wireless communication, thereby determining the group to which the shared channel mapping is generated. In step S530, the master device 20 refers to a list, etc., to filter each slave device 30A, 30B, 40A, 50A belonging to the determined group, and reads the channels that can be used for communication of each filtered slave device 30A, 30B, 40A, 50A. In step S540, the master device 20 extracts the shared communication channels, i.e., the shared communication channels, from the read communication channels of each slave device 30A, 30B, 40A, 50A. Then, in step S550, the master device 20 generates a shared channel mapping based on the extracted shared communication channels.

[0101] In this way, a new shared channel mapping is generated for each group each time a channel mapping update cycle is completed. In step S300 of the flowchart in Figure 5 above, as shown in the timing diagram of Figure 7, the generated shared channel mapping is sent to the slave device 30A within the period applicable to the current shared channel mapping, i.e., the channel mapping update cycle, at least before the shared channel mapping is successfully shared. Then, the master device 20 and the slave device 30A begin a new channel mapping update cycle and switch the shared channel mapping used in the next update cycle to the successfully shared shared channel mapping. Thus, as shown in the timing diagram of Figure 7, in the next update cycle, wireless communication between the master device 20 and the slave device 30A is performed using the newly successfully shared shared channel mapping. In this way, by periodically updating the shared channel mapping, the master device 20 and the slave device 30A can perform high-quality communication using shared channel mappings that adapt to changes in the communication quality of each communication channel.

[0102] (Second Implementation)

[0103] Next, with reference to the accompanying drawings, the wireless communication system 10 of the second embodiment of this disclosure will be described. The wireless communication system 10 of this embodiment is configured similarly to the wireless communication system 10 of the first embodiment, therefore, a description of its structure is omitted.

[0104] In the wireless communication system 10 of the first embodiment described above, multiple slave devices 30A, 30B, 40A, and 50A are grouped according to each vehicle application, and a shared channel mapping is generated for each group. However, the required communication quality may vary depending on the vehicle application. For example, in a tire pressure monitoring system, the pressure change of the monitored tire over time is minimal; therefore, even if several communication errors occur in a short period of time in the wireless communication system 10, it will not be a significant problem. Furthermore, in vehicle applications, for example, when connecting a mobile device carried by a vehicle occupant to an in-vehicle system to build an entertainment system for playing music, videos, etc., stored on the mobile device, the communication quality of the wireless communication may not be high, as it does not directly affect the control of the vehicle.

[0105] In contrast, for example, the changes in the state of a battery over time (e.g., voltage, temperature, etc.) of a battery that is the target of the battery management system are greater than the changes in tire pressure over time. Therefore, when the wireless communication system 10 is applied to the battery management system, it is desirable to avoid communication errors.

[0106] Therefore, in this embodiment, the wireless communication system 10 is configured to exclude devices from the group corresponding to the vehicle application from those whose channel mapping is updated periodically to ensure communication quality, or to use different criteria for determining the communication channels used for wireless communication. For example, by excluding slave devices belonging to a group from the updated channel mapping objects, the processing load in the master device 20 or control device 1 for performing channel mapping control can be reduced. Furthermore, for example, for vehicle applications that do not require strict communication quality, by relaxing the criteria for deleting communication channels, more communication channels can be used for wireless communication.

[0107] Hereinafter, the wireless communication system 10 of this embodiment will be described, focusing on the differences from the wireless communication system 10 of the first embodiment described above. The main difference between the wireless communication system 10 of this embodiment and the wireless communication system 10 of the first embodiment lies in the processing of the communication sequence.

[0108] Figure 11 is a flowchart illustrating an example of the communication sequence of the wireless communication system 10 according to this embodiment. In the flowchart of Figure 11, step S255 is added to the flowchart of Figure 5. Furthermore, in the flowchart of Figure 11, step S275 is performed instead of step S270 in the flowchart of Figure 5.

[0109] In step S255, the master device 20 determines whether the slave devices 30A, 30B, 40A, and 50A communicating are slave devices belonging to the non-object group excluded from the update objects of the channel mapping. If a slave device belongs to a non-object group, the master device 20 does not perform the processing after step S260 and ends the communication sequence shown in the flowchart of FIG11. Therefore, for slave devices belonging to a non-object group, the following processing is not performed: determining the communication channel for wireless communication and generating a shared channel mapping through deleting and restoring the communication channel in steps S275 and S280. Slave devices belonging to a non-object group can continue to use the initial shared channel mapping exchanged as part of the connection information in the startup sequence to communicate with the master device 20.

[0110] Furthermore, for each slave device belonging to a specified group, it can be determined whether to exclude it from the channel mapping update objects based on the communication quality of each slave device belonging to the specified group. For example, if the communication quality data of each slave device belonging to the specified group exceeds a specified benchmark, it can be determined that the wireless communication quality between the master device 20 and each slave device belonging to the specified group is good. In this case, each slave device belonging to the specified group can be excluded from the channel mapping update objects. However, in this case, since it is necessary to obtain the communication quality data of each slave device, at least the processing of step S260 in the flowchart of FIG11 and the processing of steps S275 and S280 for determining communication quality need to be executed. Moreover, if any of the communication quality data of each slave device belonging to the specified group deteriorates, it can be restored to the channel mapping update objects. Alternatively, at least one specified slave device belonging to the specified group can be excluded from the channel mapping update objects. In this case, a shared channel mapping is generated for the specified group based on the communication usability channels of the remaining slave devices other than the specified at least one slave device. In other words, the communication usability channels of the specified at least one slave device are excluded from the operation objects used to generate the shared channel mapping. In this case, when a shared channel mapping is generated and updated for the specified group, at least one of the specified slave devices also belongs to the specified group. Therefore, the updated shared channel mapping can be used to perform wireless communication with the master device 20.

[0111] In step S275, similar to step S270 in the flowchart of FIG5, the master device 20 determines that the communication quality of the communication channel used for wireless communication with the slave device 30A has deteriorated based on the communication quality data of the communication channel detected in step S260. Then, the master device 20 removes the communication channel determined to have deteriorated communication quality 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 determines the deterioration of communication quality based on the determination criteria corresponding to the group to which the slave device 30A to which it is communicating belongs. When high communication quality is required, the determination criteria are strictly set. For example, when determining communication quality based on RSSI, the threshold used as the determination criteria is set relatively high; when determining communication quality based on PER, the threshold used as the determination criteria is set relatively low. Conversely, when such high communication quality is not required, the determination criteria are relaxed. For example, when determining communication quality based on RSSI, the threshold used as the determination criteria is set relatively low; when determining communication quality based on PER, the threshold used as the determination criteria is set relatively high. Therefore, it is possible to determine whether a communication channel needs to be deleted based on the required level of communication quality.

[0112] Furthermore, the flowchart in Figure 11 only shows the determination criteria for deleting the communication channel based on the group to which the slave device belongs. However, for the determination of restoring the communication channel in step S280, the determination criteria can also be determined based on the group to which the slave device belongs. For example, when high communication quality is required, the standby time until the deleted communication channel is restored can be set to a longer time as the restoration determination criterion. Alternatively, when determining whether the deleted communication channel can be restored based on the communication quality of adjacent channels, restoration can be allowed if the communication quality of adjacent channels meets a higher determination criterion.

[0113] (Third implementation method)

[0114] Next, with reference to the accompanying drawings, the wireless communication system 10 of the third embodiment of this disclosure will be described. The wireless communication system 10 of this embodiment is configured similarly to the wireless communication system 10 of the first embodiment, therefore, a description of its structure is omitted.

[0115] In the wireless communication system 10 of the first embodiment described above, multiple slave devices 30A, 30B, 40A, and 50A are grouped according to each vehicle application. Figure 12 shows an example of the configuration of multiple slave devices S_A1 to S_A5, S_B1 to S_B4, and S_C1 grouped according to each vehicle application in a vehicle 100. In Figure 12, slave devices S_A1 to S_A5 correspond to the smart key system. Slave devices S_B1 to S_B4 correspond to the tire pressure monitoring system. In addition, in the example shown in Figure 12, the slave devices S_C1 of mobile devices held by occupants are grouped into one group.

[0116] As shown in Figure 12, when groups are formed for each vehicle application, the configuration of the corresponding slave devices S_A1 to S_A5, S_B1 to S_B4, and S_C1 can sometimes involve a wide range. In this case, it can be assumed that the communication environments (e.g., the effects of vibration and noise) of the slave devices S_A1 to S_A5 and S_B1 to S_B4 belonging to the same group are different. Therefore, when groups are formed for each vehicle application, for example, when slave devices with deteriorated communication environments are included, the number of communication channels included in the shared channel mapping may be reduced as a result.

[0117] In contrast, in this embodiment, as shown in FIG13, based on the setting position of the master device 20, multiple 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 for each of the multiple regions. The multiple regions are configured such that each region contains multiple 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. In the example shown in FIG13, six regions are set up by grouping slave devices S_A1~S_A2, S_B1~S_B2, S_C1~S_C2, S_D1~S_D2, S_E1, and S_F1 respectively.

[0118] Thus, by setting multiple regions based on the position of the master device 20, and grouping the slave devices S_A1~S_A2, S_B1~S_B2, S_C1~S_C2, S_D1~S_D2, S_E1, and S_F1 contained within the region, it is possible to group the slave devices S_A1~S_A2, S_B1~S_B2, S_C1~S_C2, S_D1~S_D2, S_E1, and S_F1 with similar communication environments into each other.

[0119] In this embodiment, slave devices belonging to at least one of the multiple groups after grouping can also be excluded from the objects of channel mapping updates to ensure communication quality. For example, if the communication quality data of slave devices belonging to at least one of the multiple groups after grouping all exceed a predetermined benchmark, it can be determined that the wireless communication quality between the master device 20 and the slave devices belonging to that group is maintained well. In this case, the slave devices belonging to that group can be excluded from the objects of channel mapping updates. However, in this case, since it is necessary to obtain the communication quality data of each slave device, at least the processing of step S260 in the flowchart of FIG11 and the processing of steps S275 and S280 for determining communication quality need to be executed.

[0120] Additionally, Figure 13 shows an example of setting multiple relatively small areas around the main device 20 based on its installation position. However, the method of setting the areas is not limited to the example shown in Figure 13. For example, as shown in Figure 14, based on the installation position of the main device 20, an interior area, an interior vehicle area, and an exterior vehicle area can be set, and the slave devices S_A1, S_B1 to S_B8, and S_C1 contained in each area can be grouped.

[0121] (Fourth Implementation)

[0122] Next, with reference to the accompanying drawings, the wireless communication system 10 of the fourth embodiment of this disclosure will be described. The wireless communication system 10 of this embodiment is configured similarly to the wireless communication system 10 of the first embodiment, therefore, a description of its structure is omitted.

[0123] In the wireless communication system 10 of the third embodiment described above, multiple regions are defined based on the location of the master device 20, and slave devices belonging to each region are grouped. In contrast, in the wireless communication system 10 of this embodiment, multiple antennas are provided on the master device 20, multiple regions are defined based on the location of the multiple antennas, and slave devices belonging to each region are grouped.

[0124] For example, as shown in FIG15, the main device 20 has multiple antennas 23A to 23E for wireless communication with multiple 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. The multiple antennas 23A to 23E are respectively disposed at different positions on the vehicle 100. Furthermore, based on the placement positions of the multiple antennas 23A to 23E, the multiple 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 are grouped for each of multiple regions. These multiple regions are configured such that each region contains a configuration position of the multiple 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 that perform wireless communication with the main device 20.

[0125] Therefore, in the wireless communication system 10 of this embodiment, it is also possible to group the slave devices S_A1~S_A2, S_B1~S_B2, S_C1, S_D1~S_D2, and S_E1~S_E3 with similar communication environments into each other, just like in the third embodiment.

[0126] (Fifth implementation method)

[0127] Next, with reference to the accompanying drawings, the wireless communication system 10 of the fifth embodiment of this disclosure will be described. The wireless communication system 10 of this embodiment is configured similarly to the wireless communication system 10 of the first embodiment, therefore, a description of its structure is omitted.

[0128] In the first embodiment described above, the corresponding slave devices are grouped according to each vehicle application. Furthermore, in the third and fourth embodiments, multiple regions are defined based on the installation positions of the master device 20 or the multiple antennas 23A-23E, and the slave devices belonging to each region are grouped. However, the grouping method is not limited to the methods described above. For example, fixed slave devices installed in fixed positions and movable slave devices can be grouped into different groups.

[0129] Hereinafter, as a fifth embodiment, several examples will be described where fixed slave devices and mobile slave devices are grouped into different groups.

[0130] Figure 16 shows a wireless communication system 10 of the smart key system as an example of this embodiment. In the example shown in Figure 16, the master device 20 and four slave devices S_A1 to S_A4 are installed in predetermined fixed positions in the vehicle 100. That is, the four slave devices S_A1 to S_A4 are fixed slave devices. In addition, one slave device S_B1 is installed on the electronic key held by the occupant of the vehicle 100. That is, the slave device S_B1 is a movable slave device. Furthermore, when multiple electronic keys exist within the range that can communicate with the master device 20, the multiple slave devices installed on these multiple electronic keys can be grouped into one group. Alternatively, the multiple slave devices installed on the multiple electronic keys can also be grouped into separate groups.

[0131] It can be assumed that the communication environment of fixed slave devices changes less over time compared to that of mobile slave devices. Therefore, as described above, by grouping fixed and mobile slave devices into different groups, it is possible to generate and update channel mappings suitable for each group.

[0132] Figure 17 shows a wireless communication system 10 for the battery management system, as another example of this embodiment. In the example shown in Figure 17, three battery stacks A to C constituting a battery pack are installed in the vehicle 100. The three battery stacks A to C are each housed in a separate housing. Slave devices S_A1 to S_A3 are respectively disposed within the housings of the three battery stacks A to C. That is, the slave devices S_A1 to S_A3 are fixed slave devices. The master device 20 is disposed within the housing of battery stack A. The master device 20 has multiple antennas. The multiple antennas are disposed within the housing of battery stack A, outside the housing of battery stack B, and within the housing of battery stack C. Thus, the master device 20 can wirelessly communicate with the slave devices S_A1 to S_A3 disposed in each housing under substantially the same conditions.

[0133] The battery management system utilizes the wireless unit of a mobile device (e.g., a smartphone) held by the occupants of vehicle 100 as a slave device S_B1. The mobile device, for example, has the function of receiving and displaying information related to the battery's status (e.g., charge level, temperature) via wireless communication between the master device 20 and the slave device S_B1. The slave device S_B1 of the mobile device is equivalent to a mobile slave device.

[0134] As shown in Figure 17, slave devices S_A1 to S_A3, which are fixed slave devices, and slave device S_B1, which is a mobile slave device, are grouped into different groups. Therefore, similar to the example shown in Figure 16, it is possible to generate and update channel mappings suitable for each group.

[0135] Alternatively, in the examples shown in Figures 16 and 17, the slave device S_B1, which is a mobile slave device, can be excluded from the objects of periodically updating the channel mapping. Furthermore, when the mobile slave device S_B1 communicates wirelessly with the master device 20, the mobile slave device S_B1 can function as the master device, and the master device 20 can function as the slave device.

[0136] Furthermore, the structure of the wireless communication system 10 of the battery management system shown in FIG17 can be implemented in various modifications. For example, as shown in FIG18, the battery stacks A to C constituting the battery pack can be housed in a common housing instead of in separate housings. Additionally, the wireless device 25, which functions as a master device and is disposed within the housing, can also be configured to function as a slave device. In this case, the wireless device 25 is configured to operate as a master device when communicating wirelessly with slave devices S_A1 to S_A3 disposed within the housing of the battery pack, and as a slave device when communicating wirelessly with a master device 20 separately disposed within the vehicle 100. That is, in this case, the wireless device 25 functions as a relay device in the communication between each slave device S_A1 to S_A3 and the master device 20, and each slave device S_A1 to S_A3 is connected to a monitoring device of each battery stack housed within the housing.

[0137] According to the structure shown in Figure 18, the main device 20 does not need to communicate separately with each slave device S_A1 to S_A3 connected to the monitoring device of each battery pack. It can obtain information related to the battery stacks contained in each battery pack or control the state of the battery stacks simply by communicating with the wireless device 25, which acts as a relay device. Furthermore, when the battery performance of the battery stacks deteriorates due to years of degradation, the battery packs can be easily replaced.

[0138] Alternatively, the communication between the wireless device 25 within the battery pack and each of the slave devices S_A1 to S_A3 can also be wired communication, as shown in FIG19, rather than wireless communication. In this case, the wireless device 25 only needs to function as a slave device that wirelessly communicates with the master device 20.

[0139] Alternatively, as shown in FIG20, the wireless device of the mobile device functions as the master device, and the wireless device 25 disposed in the housing of the battery pack functions as the slave device. Furthermore, as described above, the wireless device of the mobile device, which is a mobile slave device, can also function as the master device, and the master device 20 as the slave device, thereby enabling wireless communication between the wireless device of the mobile device and the master device 20.

[0140] (Sixth Implementation Method)

[0141] Next, with reference to the accompanying drawings, the wireless communication system 10 of the sixth embodiment of this disclosure will be described. The wireless communication system 10 of this embodiment is configured similarly to the wireless communication system 10 of the first embodiment, therefore, a description of its structure is omitted.

[0142] In this embodiment, a method for grouping multiple slave devices 30A, 30B, 40A, and 50A into multiple groups using a method different from the embodiments described above is described. The grouping method in this embodiment is not a method of pre-grouping slave devices 30A, 30B, 40A, and 50A into multiple groups based on applications, regions, fixed or mobile types, etc., but rather a dynamic grouping of multiple slave devices 30A, 30B, 40A, and 50A based on the communication channel for wireless communication determined for each slave device 30A, 30B, 40A, and 50A, such that the number of shared communication channels is above a predetermined threshold. Therefore, in this embodiment, it can also be said that slave devices with similar communication environments are grouped together based on the number of shared communication channels. Furthermore, the slave devices belonging to each group can change over time or remain unchanged. Figure 21 is a flowchart illustrating the grouping method of this embodiment.

[0143] In the initial step S610, the master device 20 selects any slave device (e.g., slave device 30A) as the object of the group. In step S620, the master device 20 determines whether more than one group has been formed. In this determination process, if no group has been formed, the master device 20 proceeds to step S630. On the other hand, if more than one group has been formed, the master device 20 proceeds to step S640.

[0144] In step S630, the master device 20 selects any slave device (e.g., slave device 30B) other than one slave device (e.g., slave device 30A) of the selected group object, and sets a group that includes the selected slave device (e.g., slave device 30B).

[0145] In step S640, the master device 20 calculates the shared communication channels for grouping the slave device (e.g., slave device 30A) of the selected grouping object into an existing group based on the communication channels of the slave device (e.g., slave device 30A) and the shared communication channels of the existing group, and calculates the number of such shared communication channels. The shared communication channel of a group refers to the communication channel shared by all slave devices belonging to that group. Furthermore, when there are multiple existing groups, in step S640, the master device 20 calculates the shared communication channels for grouping the slave device (e.g., slave device 30A) of the grouping object into an existing group for all groups, and calculates the number of such shared communication channels. Additionally, if a group is set in step S630, in step S640, the master device 20 sets the communication channels of the slave devices (e.g., slave device 30B) included in the set group as the shared communication channels of the group.

[0146] In step S650, the main device 20 determines whether a group exists whose number of shared communication channels is above a threshold, as calculated in step S640. If no group exists, the main device 20 proceeds to step S660. Conversely, if a group exists whose number of shared communication channels is above the threshold, the main device 20 proceeds to step S670.

[0147] In step S660, when grouping the slave device (e.g., slave device 30A) of the grouping object into an existing group, the number of shared communication channels decreases to below a threshold. Therefore, the master device 20 sets a new group and groups the slave device (e.g., slave device 30A) of the grouping object into the new group. On the other hand, in step S670, the master device 20 determines whether there are multiple groups with a shared communication channel number of more than the threshold. If there are no multiple groups with a shared communication channel number of more than the threshold, that is, if there is only one group with a shared communication channel number of more than the threshold, the master device 20 proceeds to step S680. On the other hand, if there are multiple groups with a shared communication channel number of more than the threshold, the master device 20 proceeds to step S690.

[0148] In step S680, the master device 20 groups the slave devices (e.g., slave device 30A) of the grouping object into groups where the number of shared communication channels is a threshold or higher. On the other hand, in step S690, the master device 20 determines whether the number of shared communication channels is the same for multiple groups where the number of shared communication channels is a threshold or higher. If the number of shared communication channels is different, the master device 20 proceeds to step S700. If the number of shared communication channels is the same, the master device 20 proceeds to step S710.

[0149] In step S700, the master device 20 selects the group with the most shared communication channels and groups the slave devices (e.g., slave device 30A) into the selected group. Conversely, in step S710, the master device 20 selects the group with the fewest slave devices among multiple groups with the same number of shared communication channels. If the number of slave devices is also the same, any group can be selected. In step S720, the master device 20 groups the slave devices (e.g., slave device 30A) into the selected group.

[0150] In step S730, the master device 20 determines whether the grouping of all slave devices is complete. If the grouping of all slave devices is not complete, the master device 20 repeats the process from step S610. If the grouping of all slave devices is complete, the master device 20 ends the grouping process shown in FIG21.

[0151] In this sixth embodiment, slave devices belonging to at least one group after grouping may also be excluded from the channel mapping update objects. For example, if the number of shared communication channels is greater than or equal to the exclusion threshold, the number of channels available for communication is relatively large, and therefore, the communication quality of each slave device belonging to that group is considered to be at a high level. That is, the communication quality level of each slave device can be determined based on the number of channels available for communication. In this case, slave devices belonging to that group may also be excluded from the channel mapping update objects.

[0152] The preferred embodiments of this disclosure have been described above. However, this disclosure is not limited to any of the above embodiments and can be implemented in various ways without departing from the spirit of this disclosure.

[0153] For example, the features described in the above embodiments can be combined with features described in other embodiments, except in cases where they cannot be combined technically.

[0154] Finally, this specification discloses several technical concepts and various combinations thereof, as listed below. These combinations of technical concepts are applicable not only to the wireless communication system 10, but also to wireless communication methods and procedures.

[0155] (Technical Concept 1)

[0156] A wireless communication system enables at least one master device (20) and a plurality of slave devices (30) to perform wireless communication via a communication channel sequentially selected from a plurality of communication channels. The wireless communication system includes: 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 and the plurality of slave devices are performing wireless communication respectively, determines the communication quality of each communication channel for slave devices belonging to at least one group of the grouping units, and determines a communication channel for wireless communication based on the determination result of the communication quality of each communication channel; and a generation unit (S290) that, for slave devices belonging to at least one group of the grouping units, extracts a common communication channel, i.e., a shared communication channel, based on the communication channel for wireless communication determined by the communication channel determination unit, and generates a shared channel mapping. The master device and the slave devices grouped into the at least one group perform wireless communication via the communication channel selected from the shared communication channel, and the shared communication channel is shown by the shared channel mapping generated by the generation unit.

[0157] (Technical Concept 2)

[0158] In the wireless communication system described in Technical Concept 1, the generating unit periodically updates the shared channel mapping by repeatedly generating it over time, thereby excluding the slave devices belonging to at least one other group besides the group of the grouping unit from the objects of the periodically updated shared channel mapping.

[0159] (Technical Concept 3)

[0160] As described in Technical Concept 1, in the wireless communication system, the slave devices belonging to two or more groups respectively of the grouping part are used as objects for the communication channel to be determined by the communication channel determination unit for wireless communication. The communication channel determination unit determines the communication channel for wireless communication for each slave device belonging to the two or more groups according to different determination criteria for each group.

[0161] (Technical Concept 4)

[0162] In the wireless communication system of any one of technical concepts 1 to 3, each of the plurality of slave devices performs wireless communication with the master device to execute one of a plurality of applications, and the grouping unit groups the slave devices corresponding to each application according to the applications of the plurality of applications.

[0163] (Technical Concept 5)

[0164] In the wireless communication system described in technical concept 1 or 2, the grouping unit groups multiple slave devices for each of multiple regions based on the location of the master device, wherein the multiple regions are configured such that each region contains the location of multiple slave devices that perform wireless communication with the master device.

[0165] (Technical Concept 6)

[0166] As described in Technical Concept 5, in the wireless communication system, the main device is installed in the vehicle, and multiple areas are divided into an interior area, an interior area, and an exterior area.

[0167] (Technical Concept 7)

[0168] As described in technical concept 1 or 2, in a wireless communication system, the master device has a plurality of antennas for wireless communication with a plurality of slave devices, the plurality of antennas being disposed at different locations, and the grouping unit grouping the plurality of slave devices for each of a plurality of regions based on the placement locations of the plurality of antennas, the plurality of regions being configured such that each region contains the configuration locations of the plurality of slave devices that perform wireless communication with the master device.

[0169] (Technical Concept 8)

[0170] The wireless communication system according to any one of technical concepts 1 to 7 includes a plurality of slave devices comprising: a fixed slave device disposed at a fixed position; and a movable slave device, wherein the grouping unit groups the plurality of slave devices in such a way that the fixed slave device and the movable slave device are in different groups.

[0171] (Technical Concept 9)

[0172] As described in Concept 8, in a wireless communication system, a mobile slave device grouped into a different group than the fixed slave device is excluded from the objects of periodically updated shared channel mappings.

[0173] (Technical Concept 10)

[0174] In the wireless communication system described in Technical Concept 8 or 9, the mobile slave device is a user-carried electronic device. When the mobile slave device communicates wirelessly with the master device, the mobile slave device functions as the master device, and the master device functions as the slave device.

[0175] (Technical Concept 11)

[0176] As described in any one of technical concepts 1 to 10, in a wireless communication system, a plurality of said slave devices have identification information for identifying each of said slave devices and transmitting said identification information in wireless communication with said master device, said master device holding a list that associates said identification information with information of a group to which it belongs, said grouping unit grouping said slave devices according to said list based on said identification information wirelessly transmitted from each of said slave devices to said master device.

[0177] (Technical Concept 12)

[0178] As described in any one of technical concepts 1 to 10, in a wireless communication system, a plurality of said slave devices have identification information for identifying each of the slave devices and group information indicating the group to which they belong, and transmit the identification information and the group information in wireless communication with the master device, 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.

[0179] (Technical Concept 13)

[0180] In the wireless communication system described in technical concept 1 or 2, the grouping unit groups multiple slave devices based on the communication channel for wireless communication determined by the communication channel determination unit for each slave device, such that the number of shared communication channels is above a predetermined threshold.

[0181] (Technical Concept 14)

[0182] In the wireless communication system described in Technical Concept 13, the packet unit determines the common communication channel for grouping the slave device into at least one of the existing groups based on the communication channel used for wireless communication by the slave device as the packet target and the common communication channel in at least one existing group. If the number of determined common communication channels is above the predetermined threshold, the slave device as the packet target is grouped into the existing group; if it is below the predetermined threshold, the slave device as the packet target is grouped into a new group.

[0183] (Technical Concept 15)

[0184] In the wireless communication system described in technical concept 13 or 14, the packet unit determines the common communication channel for grouping the slave device into at least one of the existing groups based on the communication channel used for wireless communication by the slave device as the packet target and the common communication channel in at least one existing group. If there are multiple existing groups where the number of determined common communication channels is above the predetermined threshold, the slave device as the packet target is grouped into the existing group with the largest number of determined common communication channels.

[0185] (Technical Concept 16)

[0186] In the wireless communication system of any one of technical concepts 13 to 15, the grouping unit determines the common communication channel for grouping the slave device to at least one of the existing groups based on the communication channel used for wireless communication by the slave device as the grouping target and the common communication channel in at least one existing group. If there are multiple existing groups where the number of determined common communication channels is above the predetermined threshold, and the number of determined common communication channels for these multiple existing groups is the same, the slave device as the grouping target is grouped into the existing group with a smaller number of slave devices.

Claims

1. A wireless communication system that enables at least one master device (20) to perform wireless communication with a plurality of slave devices (30) via a communication channel sequentially selected from a plurality of communication channels, the wireless communication system comprising: The grouping unit (S50) groups the plurality of said slave devices into two or more groups; The communication channel determination unit (S270, S280) determines the communication quality of each communication channel for slave devices belonging to at least one group of the grouping components when the master device and the plurality of slave devices are performing wireless communication respectively, and determines the communication channel for wireless communication based on the determination result of the communication quality of each communication channel; and the generation unit (S290) extracts a common communication channel, i.e., a shared communication channel, for the slave devices belonging to the at least one group of the grouping components based on the communication channel for wireless communication determined by the communication channel determination unit, and generates a shared channel mapping. The master device and the slave devices grouped into the at least one group perform wireless communication via the communication channel selected from the shared communication channel, and the shared communication channel is shown by the shared channel mapping generated by the generation unit.

2. The wireless communication system according to claim 1, characterized in that, The generating unit periodically updates the shared channel mapping by repeatedly generating it over time, thereby excluding the slave devices belonging to at least one other group besides the grouping unit from the objects of the periodically updated shared channel mapping.

3. The wireless communication system according to claim 1, characterized in that, The slave devices belonging to two or more groups respectively of the grouping part are regarded as objects for the communication channel determined by the communication channel determination unit for wireless communication. The communication channel determination unit determines the communication channel for wireless communication for the slave devices belonging to the two or more groups respectively, according to different determination criteria for each group.

4. The wireless communication system according to any one of claims 1 to 3, characterized in that, Each of the plurality of slave devices executes one of a plurality of applications by wirelessly communicating with the master device. Corresponding to a particular application, the grouping unit groups the slave devices corresponding to each of the plurality of applications.

5. The wireless communication system according to claim 1 or 2, characterized in that, The grouping unit groups the multiple slave devices for each of multiple regions based on the location of the master device. The multiple regions are configured such that each region contains the configuration locations of multiple slave devices that perform wireless communication with the master device.

6. The wireless communication system according to claim 5, characterized in that, The main device is installed in the vehicle, and multiple areas are divided into the vehicle interior area, the vehicle interior area, and the vehicle exterior area.

7. The wireless communication system according to claim 1 or 2, characterized in that, The master device has multiple antennas for wireless communication with multiple slave devices, and the multiple antennas are respectively arranged in different positions. The grouping unit groups the multiple slave devices for each of multiple regions based on the arrangement positions of the multiple antennas. The multiple regions are set such that each region contains the configuration positions of multiple slave devices that perform wireless communication with the master device.

8. The wireless communication system according to claim 1 or 2, characterized in that, The plurality of slave devices includes: a fixed slave device disposed at a fixed position; and a movable slave device, wherein the grouping unit groups the plurality of slave devices in such a way that the fixed slave device and the movable slave device are in different groups.

9. The wireless communication system according to claim 8, characterized in that, The mobile slave device, grouped into a different group than the fixed slave device, is excluded from the objects of periodically updated shared channel mappings.

10. The wireless communication system according to claim 8, characterized in that, The mobile slave device is an electronic device carried by the user. When the mobile slave device communicates wirelessly with the master device, the mobile slave device functions as the master device, and the master device functions as the slave device.

11. The wireless communication system according to claim 1, characterized in that, The plurality of slave devices have identification information for identifying each of the slave devices and transmitting the identification information in wireless communication with the master device. The master device holds a list that associates the identification information with information of the group to which it belongs. 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.

12. The wireless communication system according to claim 1, characterized in that, The plurality of slave devices have identification information for identifying each slave device and group information indicating the group to which they belong, and transmit the identification information and the group information in wireless communication with the master device. 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. The wireless communication system according to claim 1 or 2, characterized in that, The grouping unit groups multiple slave devices based on the communication channel for wireless communication determined by the communication channel determination unit for each slave device, such that the number of shared communication channels is above a predetermined threshold.

14. The wireless communication system according to claim 13, characterized in that, The grouping unit determines the common communication channels when grouping the slave device into at least one existing group, based on the communication channels used for wireless communication by the slave device as the grouping target and the common communication channels in at least one existing group. If the number of determined common communication channels is above the predetermined threshold, the slave device as the grouping target is grouped into the existing group; if it is below the predetermined threshold, the slave device as the grouping target is grouped into a new group.

15. The wireless communication system according to claim 13, characterized in that, The grouping unit determines the common communication channel for grouping the slave device into at least one existing group based on the communication channel used for wireless communication of the slave device as the grouping target and the common communication channel in at least one existing group. If there are multiple existing groups where the number of the determined common communication channels is above the predetermined threshold, the slave device as the grouping target is grouped into the existing group with the largest number of determined common communication channels.

16. The wireless communication system according to claim 13, characterized in that, The grouping unit determines the common communication channel for grouping the slave device into at least one existing group based on the communication channel used for wireless communication by the slave device as the grouping target and the common communication channel in at least one existing group. If there are multiple existing groups where the number of common communication channels determined is above the predetermined threshold, and the number of common communication channels determined for these multiple existing groups is the same, the slave device as the grouping target is grouped into the existing group with a smaller number of slave devices.

17. A wireless communication method for enabling at least one master device (20) and a plurality of slave devices (30) to perform wireless communication via a communication channel sequentially selected from a plurality of communication channels, the wireless communication method comprising the steps of: grouping the plurality of slave devices into two or more groups (S50); when the master device and the plurality of slave devices are performing wireless communication respectively, determining the communication quality of each communication channel for the slave devices belonging to at least one group after grouping, and determining a communication channel for wireless communication based on the determination result of the communication quality of each communication channel (S270, S280); and for the slave devices belonging to the at least one group after grouping, extracting a common communication channel, i.e., a shared communication channel, based on the determined communication channel for wireless communication, and generating a shared channel mapping (S290), wherein the master device and the slave devices grouped into the at least one group perform wireless communication via the communication channel selected from the shared communication channel shown in the generated shared channel mapping.

18. A wireless communication program for enabling at least one master device (20) and a plurality of slave devices (30) to perform wireless communication via a communication channel sequentially selected from a plurality of communication channels, the wireless communication program causing at least one processor to perform the following actions: grouping the plurality of slave devices into two or more groups (S50); when the master device and the plurality of slave devices are performing wireless communication respectively, determining the communication quality of each communication channel for the slave devices belonging to at least one group after grouping, and determining the communication channel for wireless communication based on the determination result of the communication quality of each communication channel (S270, S280); and for the slave devices belonging to the at least one group after grouping, extracting a common communication channel, i.e., a shared communication channel, based on the determined communication channel for wireless communication, and generating a shared channel mapping (S290), the master device and the slave devices grouped into the at least one group performing wireless communication via the communication channel selected from the shared communication channel shown in the generated shared channel mapping.

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