Wireless communication system, wireless communication method, and persistent computer-readable medium

Abstract

A wireless communication system, a wireless communication method, and a persistent computer-readable medium are provided. A slave device (30) to which channel mapping sharing is to be performed is determined on the basis of the communication state of wireless communication between a master device (20) and each of a plurality of slave devices (30). Thus, it is possible to suppress a processing load when performing channel mapping control, and to avoid an increase in system cost. Furthermore, when the number of slave devices (30) determined to be the subject of channel mapping control is small, the channel mapping sharing timing is advanced among all of the determined slave devices (30) compared to when the number of slave devices (30) determined to be the subject of channel mapping control is large than when the number of slave devices (30) determined to be larger than the number of slave devices (30) determined to be larger than the number of slave devices (30) determined to be larger than the number.

Description

Technical Field

[0001] The present disclosure relates to a wireless communication system, a wireless communication method, and a command included in a persistent computer readable medium, in which a master device performs wireless communication with a slave device via one communication channel selected sequentially from a plurality of communication channels. Background Art

[0002] As such a wireless communication system, there is known a system described in Patent Document 1, for example. In the wireless communication system of Patent Document 1, when a data packet error occurs in a received signal of a wireless communication device, and the RSSI value of the wireless signal of the data packet is greater than a preset threshold value Th1, the wireless communication device determines that the reception error is caused by interference between the reception action of receiving the data packet and other radio waves. In addition, the wireless communication device counts the number of receptions and the number of reception errors, and stores the frequency of reception errors caused by interference in each frequency channel (number of reception errors / number of receptions). When the reception error frequency exceeds the threshold value 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 value Th2, and stores the frequency channel as an unusable channel.

[0003] Prior Art Literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2006-128812 Summary of the invention

[0006] Problems to be solved by the invention

[0007] As described above, the wireless communication system of Patent Document 1 sets a frequency channel whose communication quality is reduced due to interference with other radio waves as an unusable channel. In addition, the wireless communication system of Patent Document 1 restores the frequency channel set as an unusable channel to an available frequency channel after a set period has passed. Hereinafter, in this specification, such control of setting a frequency channel as an unusable channel or restoring it to an available channel is referred to as channel mapping control.

[0008] Here, the wireless communication system includes at least one master device and at least two or more slave devices. When multiple slave devices respectively communicate wirelessly with the master device, channel mapping control needs to be performed for each of the multiple slave devices. Channel mapping control is mainly implemented by a computer with a processor using software processing according to a program. Therefore, the more slave devices there are, the more the computer processing load for channel mapping control increases. Therefore, if channel mapping control is to be implemented for all slave devices, a high-performance computer needs to be used, which may increase the cost of the wireless communication system.

[0009] The present disclosure is made in view of the above-mentioned points, and its purpose is to provide a wireless communication system, a wireless communication method and a command possessed by a persistent computer-readable medium, which can ensure the effect of channel mapping control in a wireless communication system in which a master device communicates with multiple slave devices and suppress the increase in the cost of the wireless communication system.

[0010] Solutions to Solve Problems

[0011] In order to achieve the above-mentioned object, the wireless communication system of the present disclosure is a system in which a master device performs wireless communication with a slave device via a communication channel selected sequentially from a plurality of communication channels, wherein:

[0012] The wireless communication system is composed of:

[0013] There are multiple slave devices, and the master device communicates wirelessly with each of the multiple slave devices.

[0014] The wireless communication system has:

[0015] a communication channel determination unit that determines the communication quality of each communication channel for each slave device when the master device performs wireless communication with a plurality of slave devices, and determines a communication channel for wireless communication based on the determination result of the communication quality of each communication channel;

[0016] a channel map sharing unit that transmits a channel map representing the communication channel determined by the communication channel determination unit from the master device to the corresponding slave device so that the master device and the corresponding slave device share the channel map;

[0017] a slave device determining unit that determines a slave device to be a target of sharing of channel mapping by the channel map sharing unit, based on a communication state of wireless communication between the master device and each of the plurality of slave devices; and

[0018] A timing changing unit that, when the number of slave devices determined by the slave device determining unit is small, advances the timing of sharing the channel mapping by the channel mapping sharing unit among all the determined slave devices, compared to a case where the number of slave devices determined is large.

[0019] In addition, the wireless communication method of the present disclosure is a method in which a master device performs wireless communication with a slave device via one communication channel sequentially selected from a plurality of communication channels, wherein:

[0020] The wireless communication method is constituted as follows:

[0021] The master device communicates wirelessly with multiple slave devices.

[0022] Wireless communication methods include:

[0023] a communication channel determination step, in which, when the master device performs wireless communication with a plurality of slave devices, the communication quality of each communication channel is determined for each slave device, and a communication channel used for wireless communication is determined based on the determination result of the communication quality of each communication channel;

[0024] a channel mapping sharing step of transmitting the channel mapping indicating the communication channel determined in the communication channel determining step from the master device to the corresponding slave device so that the master device and the corresponding slave device share the channel mapping;

[0025] a slave device determining step of determining a slave device to be a target of sharing the channel mapping in the channel mapping sharing step, based on the communication status of the wireless communication between the master device and each of the plurality of slave devices; and

[0026] The timing changing step advances the timing of sharing the channel mapping in the channel mapping sharing step among all the determined slave devices when the number of slave devices determined in the slave device determining step is small, compared to when the number of slave devices determined is large.

[0027] In addition, the persistent computer-readable medium of the present disclosure is a medium having a command executed by at least one processor, wherein the command is for the master device to perform wireless communication with the slave device via a communication channel sequentially selected from a plurality of communication channels,

[0028] The non-volatile computer readable medium is constituted by:

[0029] The master device communicates wirelessly with multiple slave devices.

[0030] When the command is executed, at least one processor is enabled to:

[0031] a communication channel determination function for determining the communication quality of each communication channel for each slave device when the master device is communicating wirelessly with a plurality of slave devices, and determining a communication channel for wireless communication based on the determination result of the communication quality of each communication channel;

[0032] a channel mapping sharing function that transmits a channel mapping representing a communication channel determined by the communication channel determination function from the master device to a corresponding slave device so that the master device and the corresponding slave device share the channel mapping;

[0033] A slave device determination function that determines a slave device to be a target of sharing of channel mapping by the channel mapping sharing function, based on a communication state of wireless communication between the master device and each of the plurality of slave devices; and

[0034] The timing change function advances the timing of sharing the channel mapping by the channel mapping sharing function among all the determined slave devices when the number of slave devices determined by the slave device determination function is small, compared to when the number of the determined slave devices is large.

[0035] As described above, in the commands provided by the wireless communication system, wireless communication method, and persistent computer-readable medium of the present disclosure, the slave device that is the shared object for implementing channel mapping is determined based on the communication status of the wireless communication between the master device and each of the plurality of slave devices. Thus, in the present disclosure, instead of always implementing channel mapping control on all slave devices, the slave device for implementing channel mapping control is determined based on the communication status. Thus, the processing load when implementing channel mapping control can be suppressed. As a result, channel mapping control can be performed even without using a high-performance computer, and the cost of the system can be avoided from increasing.

[0036] Furthermore, in the commands possessed by the wireless communication system, wireless communication method, and persistent computer-readable medium of the present disclosure, it is configured that, when the number of slave devices determined to be the objects of channel mapping control is small, the timing of sharing the channel mapping is advanced among all the determined slave devices compared to the case where the number of determined slave devices is large. Therefore, for example, in the case where there are slave devices whose communication status has deteriorated, the timing of sharing the channel mapping can be advanced by reducing the number of slave devices that become the objects of sharing to implement channel mapping. As a result, it is possible to achieve early improvement of the communication status of the slave device whose communication status has deteriorated. In this way, the effect of the channel mapping control can be ensured.

[0037] The reference signs in the above parentheses are merely signs showing an example of the correspondence relationship with the specific configurations in the embodiments described later in order to facilitate understanding of the present disclosure, and are not intended to limit the scope of the present disclosure at all.

[0038] In addition, technical features described in each of the claims other than the features of the present disclosure described above will become clear from the description of the embodiments described later and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 This is a block diagram showing a schematic configuration of a wireless communication system according to the first embodiment.

[0040] Figure 2 This is a diagram showing an example of the electric field intensity distribution in the communication environment between the master device and the slave device.

[0041] Figure 3 This is a diagram showing an example of the received signal strength of each communication channel.

[0042] Figure 4 This is a flowchart showing an example of a communication sequence between a master device and a slave device.

[0043] Figure 5 Yes means Figure 4 The flowchart is a flowchart of an example of a process determined by a slave device as an object of the flowchart.

[0044] Figure 6 Yes means Figure 4 A flowchart of an example of a channel mapping sending process.

[0045] Figure 7 This is a timing chart showing an example of the timing of updating the channel map of each slave device when all slave devices are set as the target of channel map control.

[0046] Figure 8 This is a timing chart showing an example of the timing of updating the channel mapping of each slave device when a part of the slave devices are set as the target of channel mapping control.

[0047] Fig. 9 This is a flowchart showing an example of the target slave device determination process according to the second embodiment.

[0048] Fig.10 This is a flowchart showing an example of the channel mapping transmission process according to the second embodiment.

[0049] Fig.11 This is a timing chart showing an example of the timing of updating the channel map of each slave device when a slave device whose communication status has deteriorated is made a target of channel map control in the second embodiment. DETAILED DESCRIPTION

[0050] Hereinafter, preferred embodiments of the present disclosure will be described with reference to the accompanying drawings. In addition, for identical or similar structures, descriptions are sometimes omitted by marking the same reference numerals throughout a plurality of drawings. In the case where only a portion of a structure is described in each embodiment, the other portions of the structure can be applied to the structures of other embodiments previously described. In addition, not only the combinations of structures explicitly described in the description of each embodiment, but also the structures of a plurality of embodiments may be partially combined with each other even if not explicitly described, as long as the combination does not particularly cause obstacles.

[0051] (First Embodiment)

[0052] The wireless communication system of this embodiment includes at least one master device and at least two slave devices. The at least two slave devices respectively communicate wirelessly with one master device. At least one of the master device and the plurality of slave devices can be mounted on a mobile object for use. The mobile object includes, for example, vehicles such as automobiles and railway vehicles, flying objects such as electric vertical take-off and landing aircraft and drones, ships, construction machinery, agricultural machinery, etc.

[0053] As a specific application in a vehicle, the wireless communication system of this embodiment can be applied to a battery management system for managing batteries mounted as battery packs in electric vehicles such as electric vehicles, hybrid vehicles, and plug-in hybrid vehicles. When applied to a battery management system, for example, a master device is connected to a battery control device, and a plurality of slave devices are respectively connected to monitoring devices provided on a plurality of battery stacks constituting the battery pack. In this case, the master device and the plurality of slave devices are all mounted on the vehicle.

[0054] Each monitoring device provided for each of the plurality of battery stacks uses various sensors to obtain battery information such as the voltage and current of each battery cell contained in the corresponding battery stack, the temperature of the battery stack, etc. In addition, when each monitoring device receives data requesting battery information from the battery control device via the wireless communication system, it sends the obtained battery information to the battery control device via the wireless communication system. Based on the obtained battery information, the battery control device calculates the charge capacity (SOC) of the entire battery stack, drives the heating / cooling mechanism to adjust the temperature of the battery pack to an appropriate range, and determines whether it is necessary to perform the so-called equalization process to make the voltage of each battery cell consistent. When the battery control device determines that the equalization process needs to be performed in at least one battery stack, it instructs the corresponding monitoring device to perform the equalization process via the wireless communication system. In addition, each monitoring device performs a process for determining the abnormality of various sensors and the abnormality of its own operation, and when an abnormality is determined, it sends abnormal information to the battery control device via the wireless communication system.

[0055] Alternatively, the wireless communication system of this embodiment can also be applied to a so-called smart key system or a tire pressure monitoring system in a vehicle. When applied to a smart key system, for example, a master device is mounted on a vehicle and connected to a control device for controlling the locking and unlocking of vehicle doors and the starting and shutting down of a driving source such as an engine of the vehicle. Multiple slave devices are mounted on mobile keys or portable terminals owned by multiple users. When applied to a tire pressure monitoring system, a master device is mounted on a vehicle and connected to a control device for displaying tire pressure, issuing warnings in the event of abnormal air pressure, and the like. Multiple slave devices are disposed in each tire and connected to an air pressure detection device that is also disposed in each tire.

[0056] Furthermore, the wireless communication system of this embodiment can also be applied to a vehicle diagnostic system. In this case, for example, multiple slave devices are connected to multiple vehicle-mounted equipment with self-diagnosis functions, and the master device is connected to a diagnostic control device installed in a service plant. In the above example, the master device and at least one of the multiple slave devices are arranged at a fixed position, and / or the master device and at least one of the multiple slave devices are mounted on the vehicle.

[0057] However, the application examples of the wireless communication system of this embodiment are not limited to vehicles, and as mentioned above, it can also be applied to systems that control and manage various equipment such as mobile objects other than vehicles, such as flying objects such as drones, ships, construction machinery, agricultural machinery, etc. Furthermore, the wireless communication system of this embodiment can also be applied to systems that control and manage various equipment in buildings such as buildings, production equipment such as factories, etc.

[0058] Figure 1 : is a block diagram showing a simplified structure of a wireless communication system 10. The master device 20 and the slave device 30 of the wireless communication system 10 are both mounted on, for example, a vehicle (car). At this time, the master device 20 and the slave device 30 can be configured as a structure configured in a common frame, or can be configured as a structure not configured in a common frame. The master device 20 can be one or more. In the case of providing multiple master devices 20, the multiple master devices 20 can communicate with multiple slave devices 30 belonging to different groups, respectively, and the multiple master devices 20 can also communicate with multiple slave devices 30 belonging to the same group. The master device 20 and the slave device 30 perform wireless communication via a communication channel selected sequentially from multiple communication channels, for example, in the manner of Bluetooth Low Energy (Bluetooth is a registered trademark, hereinafter referred to as Bluetooth LE) communication.

[0059] As an example, the wireless communication system 10 of this embodiment includes a master device 20 and a plurality of slave devices 30. Figure 1 In the figure, only one slave device 30 is shown for simplicity of illustration, but a plurality of slave devices 30 can be configured in the same manner.

[0060] In the wireless communication between the master device 20 and the slave device 30, frequency bands used in short-range communication, such as the 2.4 GHz band and the 5 GHz band, can be used. Compared with the radio waves in the LF band, radio waves in such high-frequency bands have the property of being more straight-traveling and being easily reflected by metal objects such as the body of a vehicle. LF is the abbreviation of Low Frequency. As standards for short-range communication, for example, Bluetooth, Bluetooth LE, etc. can be used. As an example, the master device 20 and the slave device 30 of the present embodiment are configured to be able to implement wireless communication in accordance with the Bluetooth LE standard (hereinafter referred to as Bluetooth LE communication). The details of the communication method involving communication connection and encrypted communication are implemented according to the timing specified by the Bluetooth LE standard.

[0061] The main device 20 is as follows Figure 1 The master device 20 is shown as having a control circuit (CNT) 21, a wireless communication circuit (WC) 22, and an antenna 23. In addition to the above elements, the master device 20 also has an input / output interface and a bus for communicating with devices other than the slave device 30 by wire or wireless. In addition, the processing such as the channel mapping control processing, the channel mapping production processing, and the channel mapping sharing processing described later can be implemented by the control circuit 21, or part or all of these processing can be implemented by other control devices provided outside the master device 20.

[0062] The control circuit 21 is, for example, a computer including a processor 211 and a memory 212. The memory 212 includes, for example, a RAM and a ROM. RAM is an abbreviation of Random Access Memory, and ROM is an abbreviation of Read Only Memory.

[0063] In the control circuit 21, the processor 211 uses the RAM as a temporary storage area and executes the program stored in the ROM, thereby performing the specified processing (control). The processor 211 constructs multiple functional units by executing multiple commands contained in the program. There can also be multiple processors 211. The storage medium of the program is not limited to ROM. For example, various storage media such as HDD and SSD can be used. HDD is the abbreviation of Hard-disk Drive. SSD is the abbreviation of Solid State Drive.

[0064] The processor 211 is, for example, a CPU, an MPU, a GPU, a DFP, etc. CPU is the abbreviation of Central Processing Unit. MPU is the abbreviation of Micro-Processing Unit. GPU is the abbreviation of Graphics Processing Unit. DFP is the abbreviation of Data Flow Processor. The control circuit 21 can be implemented by combining multiple types of computing processing devices such as CPU, MPU, GPU, etc. Alternatively, the control circuit 21 can also be implemented as a SoC. SoC is the abbreviation of System on Chip. The control circuit 21 can be implemented using ASIC or FPGA. ASIC is the abbreviation of Application Specific Integrated Circuit. FPGA is the abbreviation of Field-Programmable Gate Array.

[0065] The control circuit 21 generates a command to request processing from the slave device 30 (e.g., a command to request data, a command to request execution of a predetermined process, etc.), and transmits the transmission data including the command to the wireless communication circuit 22 using a transmission data packet. In addition, the control circuit 21 receives a data packet transmitted from the slave device 30, and executes a predetermined process based on the data included in the received data packet. That is, the wireless communication performed between the master device 20 and the slave device 30 is a data packet communication.

[0066] The wireless communication circuit 22 includes an RF circuit (not shown) for wirelessly transmitting and receiving data packets. The wireless communication circuit 22 has a transmission function of modulating a transmission signal and oscillating it at the frequency of an RF signal. The wireless communication circuit 22 has a reception function of demodulating a reception signal. RF is the abbreviation of radio frequency.

[0067] The wireless communication circuit 22 modulates the data packet containing data sent from the control circuit 21 and sends it to the slave device 30 via the antenna 23. The control circuit 21 outputs the data obtained by encrypting the transmission data such as the battery information request data using the encryption information exchanged in the connection establishment process described later to the wireless communication circuit 22. The wireless communication circuit 22 assigns the data required for wireless communication such as communication control information to the transmission data packet and sends it. The data required for wireless communication includes, for example, an identifier (ID), a sequence number, a next sequence number, an error detection code, etc. The wireless communication circuit 22 can also control the data size, communication format, scheduling, error detection, etc. of the communication between the master device 20 and the slave device 30. The above-mentioned control related to communication can also be performed by the control circuit 21.

[0068] The wireless communication circuit 22 receives and demodulates the data packet transmitted from the device 30 via the antenna 23. Then, the demodulated data packet is transmitted to the control circuit 21. The antenna 23 converts the electrical signal into a radio wave and radiates it into space. The antenna 23 receives the radio wave propagating in space and converts it into an electrical signal.

[0069] like Figure 1 As shown, the slave device 30 includes a control circuit (CNT) 31, a wireless communication circuit (WC) 32, and an antenna 33. In addition to the above elements, the slave device 30 also includes an input / output interface and a bus for communicating with devices other than the master device 20 by wire or wireless. 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, a RAM and a ROM.

[0070] The control circuit 31 performs the requested processing (response processing such as obtaining the requested data and returning it, execution processing of the requested processing, etc.) based on the request instruction obtained via the wireless communication circuit 32. For example, in the case where the request instruction contained in the received data is a request to send battery information, the control circuit 31 of the slave device 30 sends the sending request to the corresponding battery stack monitoring device to obtain the battery information from the monitoring device. In addition, the control circuit 31 sends the data encrypted using encryption information containing the processing result (such as the obtained battery information) to the wireless communication circuit 32 as a response to the request. The control circuit 31 can also perform, for example, control of a device mounted on a vehicle according to the requested processing.

[0071] The wireless communication circuit 32 includes an RF circuit (not shown) for wirelessly transmitting and receiving data packets. The wireless communication circuit 32 has a transmitting function and a receiving function similar to the wireless communication circuit 22. The wireless communication circuit 32 receives a data packet transmitted from the host device 20 via the antenna 33 and demodulates the data packet. And, the data contained in the demodulated data packet is transmitted to the control circuit 31. The wireless communication circuit 32 modulates the data packet containing data transmitted from the control circuit 31 and transmits it to the host device 20 via the antenna 33. The wireless communication circuit 32 adds data required for wireless communication such as communication control information to the transmission data packet and transmits it.

[0072] The wireless communication circuit 32 may also control the data size, communication format, scheduling, error detection, etc. of the communication between the master device 20 and the slave device 30. The above-mentioned control related to communication may also be performed by the control circuit 31. The antenna 33 converts the electrical signal into an electric wave and radiates it into space. The antenna 33 receives the electric wave propagating in the space and converts it into an electrical signal.

[0073] Figure 2 This is a diagram showing an example of the electric field intensity distribution in the communication environment between the master device 20 and the slave device 30 . Figure 2 The electromagnetic field simulation results at a predetermined timing at a predetermined frequency are shown. Hereinafter, the electric field intensity distribution may be expressed as the electric field distribution.

[0074] The master device 20 and the slave device 30 are, for example, arranged at specified positions in a vehicle. When radio wave signals of a specified frequency are transmitted from the master device 20 and the slave device 30 respectively arranged at specified positions, portions with high and low electric field strengths are generated in the use environment due to interference between the transmitted waves and reflected waves or interference with external noise. The reflected waves are generated by reflections from metal elements of the vehicle existing around the master device 20 and the slave device 30, such as reflections from the vehicle body, reflections from metal frames, reflections from wiring harnesses, and the like. For this reason, multiple Figure 2 The portion with strong electric field intensity and the portion with weak electric field intensity as shown are so-called NULL points.

[0075] If the slave device 30 is located in or near a portion of the electric field with weak electric field strength in the electric field distribution between the slave device 30 and the master device 20, the slave device 30 is more likely to fail to correctly receive the wireless communication signal from the master device 20, resulting in a communication error. A communication channel with a high probability of such a communication error is a communication channel with reduced communication quality.

[0076] Here, when the master device 20 and the slave device 30 perform wireless communication via a communication channel selected sequentially from a plurality of communication channels, since the frequencies of the communication channels are different, the electric field distribution of the communication channels also changes. As a result, the communication quality in each communication channel will be different.

[0077] For example, Figure 3 As shown, in the wireless communication performed via the communication channel A, the received power (received signal strength), which is one of the parameters indicating the communication quality, is good. In addition, in the wireless communication performed via the communication channel C, the received power shows a very high value. Therefore, when the master device 20 and the slave device 30 use the communication channels A and C with good or very high communication quality, high-quality wireless communication with communication errors sufficiently suppressed can be performed. On the other hand, in the wireless communication performed via the communication channels B and N, the received power is reduced. Therefore, when the master device 20 and the slave device 30 use the communication channels B and N with reduced communication quality, the possibility of communication errors occurring in the wireless communication becomes high. In addition, in Figure 3 In FIG. 1 , for easy understanding, an example of received signal strength relative to frequency is shown by a solid line.

[0078] Therefore, it is preferable that the wireless communication between the master device 20 and the slave device 30 be performed using a communication channel that enables high-quality wireless communication, avoiding a communication channel with reduced communication quality.

[0079] However, the electric field distribution between the master device 20 and the slave device 30 changes depending on the external environment (noise from the outside, etc.), the vibration of the master device 20 and / or the slave device 30 (including the vibration of the wiring harness), etc. Therefore, when the master device 20 and / or the slave device 30 are mounted on a mobile body such as a vehicle, the electric field distribution of the communication environment between the master device 20 and the slave device 30 changes, for example, depending on the state of the mobile body, the state of the surrounding environment of the mobile body, etc. As a result, the communication channel with good communication quality and the communication channel with reduced communication quality are not fixed, and there is a possibility of changing at all times. Therefore, it is required to delete the corresponding communication channel from the multiple communication channels used for wireless communication in response to the reduction of communication quality, and to restore the corresponding communication channel to one of the multiple communication channels used for wireless communication in response to the recovery of communication quality.

[0080] In the wireless communication system 10 of the present embodiment, as a plurality of communication channels for wireless communication, a control process for realizing wireless communication between the master device 20 and the slave device 30 by removing a communication channel with reduced communication quality and using a communication channel with a certain communication quality is described with reference to FIG. Figure 4 The communication sequence between the master device 20 and the slave device 30 is described with reference to FIG. Figure 4In FIG. 1 , the master device 20 is represented as MASTER (master device), and the slave device 30 is represented as SLAVE (slave device). Figure 4 FIG. 2 shows a communication sequence performed between the master device 20 and one slave device 30. The master device 20 and the plurality of slave devices 30 independently implement Figure 4 The communication timing is shown.

[0081] First, the master device 20 and the slave device 30 execute Figure 4 Before the communication sequence shown, a connection establishment process is performed. For example, in a case where the wireless communication system 10 is mounted on a vehicle, if the IG signal is switched from disconnected to connected due to a user's operation, a connection establishment process is performed. The connection establishment process is performed between the master device 20 and all the slave devices 30 that are connected to the master device 20 for wireless communication. In addition, in a case where the master device 20 and the slave device 30 are always connected, the connection establishment process is performed only once at a prescribed timing. However, in a case where an error occurs in the communication and the wireless communication connection between the master device 20 and the slave device 30 is cut off, a connection establishment process is sometimes performed in order to reconnect.

[0082] In the connection establishment process, for example, the slave device 30 performs a broadcast action of sending a broadcast signal via a communication channel for broadcasting, and the master device 20 performs a scanning action of scanning the broadcast signal. The communication channel for broadcasting includes multiple (for example, three in the case of Bluetooth LE) communication channels. When the master device 20 receives a broadcast signal via a certain communication channel through a scanning action, it sends a connection request to the slave device 30 that sent the broadcast signal. Thus, a communication connection is established between the master device 20 and the slave device 30. Furthermore, after the communication connection is established, the master device 20 and the slave device 30 exchange encryption information for data communication and share initial information related to frequency channel hopping. The initial information includes, for example, channel mapping, frequency hopping mode, or a function for frequency hopping.

[0083] When the connection establishment process is completed, the master device 20 and the slave device 30 execute the following for each communication event that is generated periodically: Figure 4 The communication sequence is shown in the flowchart of FIG. In this communication sequence, for each communication event, data communication is performed via a communication channel for data selected sequentially from a plurality of communication channels by using frequency channel hopping. For each communication event, the master device 20 sequentially allocates communication periods to a plurality of slave devices 30, thereby generating sub-communication events for communicating with each of the plurality of slave devices 30 in a predetermined order.

[0084] like Figure 4As shown, the master device 20 sends a request instruction such as data to the slave device 30 in step S10, that is, sends a data request. However, in addition to the data request, the master device 20 can also send a request to execute a prescribed process, etc. When the slave device 30 receives the data request in step S210, it performs a checksum determination based on the error detection code contained in the received data request in step S220 to confirm whether the data request is correctly received. In the case where the slave device 30 determines that the data request is not correctly received based on the checksum determination result in the process of step S220, for example, in step S230, it sends a signal indicating that the data request is not correctly received or a signal requesting to send the data request again. On the other hand, in the case where the slave device 30 determines that the data request is correctly received in the process of step S220, in step S230, it executes a prescribed process required for the response, such as a process of obtaining the requested data and sending it.

[0085] In addition, the master device 20 and the slave device 30 perform frequency channel hopping for each communication event as described above to switch the communication channel for data to be used, thereby transmitting and receiving data requests and requested data. At this time, the master device 20 and the slave device 30 determine the communication channel to be switched by frequency channel hopping according to the channel mapping they each have. In the case of Bluetooth LE, 37 communication channels are prepared as communication channels for data.

[0086] The master device 20 receives the requested data in step S20. And, in step S30, the master device 20 performs, for example, a checksum determination based on the error detection code included in the received data to confirm whether the data is correctly received. In the following step S40, if the master device 20 determines that the data is not correctly received in the process of step S30, or if the slave device 30 receives a signal indicating that the data request is not correctly received or a signal requesting to resend the data request, it determines whether to perform the resending process within the same communication event. For example, the master device 20 can be designed to determine that if there is a margin to perform resending before the end time of this communication event (sub-communication event), it is determined to perform resending, and if there is no margin, it is determined not to perform resending. In step S40, if the master device 20 determines to perform resending, it performs the process from step S10 again. If it is determined that the data is not correctly received in the process of step S30 or if it is determined not to perform resending in step S40, the master device 20 enters the process of step S50.

[0087] In step S50, the main device 20 performs processing based on the information included in the received data. In addition, if it is determined in the process of step S30 that the data is not correctly received and it is determined in the process of step S40 not to resend, the process of step S50 can be omitted or the process of step S50 can be performed based on the previously received data.

[0088] In step S60, the master device 20 detects a received signal strength indicator (RSSI) and a packet error rate (PER) as characteristic data indicating the communication quality of the signal received from the slave device 30. RSSI is an indicator indicating the strength of a signal transmitted from the slave device 30 and received by the master device 20. PER expresses the ratio of the number of error packets to the number of received packets of the master device 20 in percentage. The master device 20 may also detect a signal-to-noise ratio (SNR) / signal-to-interference-and-noise ratio (SINR) instead of RSSI. SNR / SINR can be detected, for example, based on the ratio of the RSSI value when the master device 20 receives a wireless communication signal from the slave device 30 to the RSSI value when the wireless communication signal is not received. In addition, the master device 20 may also detect a bit error rate (BER: bit error ratio) or a packet arrival rate (PAR) instead of PER. The master device 20 stores and accumulates the detected RSSI or SNR / SINR and at least one of PER, BER or PAR for each communication channel. In addition, in addition to or instead of being detected by the master device 20 as described above, characteristic data representing communication quality can also be acquired by the slave device 30 detecting RSSI, PER, etc. when receiving a wireless communication signal from the master device 20 and sending them to the master device 20.

[0089] In step S70, the master device 20 determines whether the communication quality of the communication channel used in the wireless communication with the slave device 30 has been reduced based on the characteristic data indicating the communication quality of the communication channel detected in step S60. Furthermore, the master device 20 deletes the communication channel determined to have reduced communication quality from the communication channels used for the wireless communication between the master device 20 and the slave device 30. In addition, the deleted communication channel is a communication channel for data. For example, an example of a condition for determining whether the communication quality has been reduced is that the RSSI is compared with a threshold value for RSSI and the PER is compared with a threshold value for PER, and the result is that at least one of the RSSI and the PER does not satisfy the threshold value. In addition, the parameter compared with the threshold value may be one. In addition, the parameter compared with the threshold value may be the parameter just before detected in step S60, or may be a value obtained by averaging a predetermined number of parameters detected in a plurality of past wireless communications related to the same communication channel or a median value thereof.

[0090] In step S80, the master device 20 performs a recovery determination of the communication channel that has been deleted according to the deletion determination in the communication event so far. In the recovery determination, if the prescribed recovery condition is met, the deleted communication channel is restored as a communication channel for wireless communication. For example, as an example of a prescribed recovery condition, it can be set to restore the deleted communication channel based on the fact that a prescribed time has passed since the deletion of the communication channel. Alternatively, as another example of a prescribed recovery condition, it can also be set to restore the deleted communication channel to a communication channel for wireless communication based on the fact that a communication channel adjacent to the deleted communication channel shows good communication quality. In this way, the communication channel that is determined to be recoverable as a communication channel for wireless communication is incorporated into the channel mapping and is actually used in the wireless communication between the master device 20 and the slave device 30. However, if the communication quality when actually used for wireless communication is still reduced, it will become the object of deletion again according to the deletion determination.

[0091] In step S90, the master device 20 implements a channel mapping production process based on the deletion determination result of step S70 and the restoration determination result of step S80. In the present embodiment, independent channel mappings are produced for each of the multiple slave devices 30. However, a common channel mapping may also be produced for the multiple slave devices 30. In the case of producing a common channel mapping, an AND operation (AND operation) of the communication channels included in the channel mapping of each slave device 30 is performed and a plurality of communication channels common to each channel mapping are extracted. In the case of producing a common channel mapping, a common channel mapping may also be produced according to the channel mapping of the slave device 30 determined as the object of channel mapping control in the object slave device determination process described later.

[0092] The channel map may indicate a communication channel that can be used in wireless communication, or may indicate an unusable communication channel. Furthermore, both usable communication channels and unusable communication channels may be indicated. In addition, when the usable / unusable communication channels are changed due to the creation of the channel map, the frequency channel hopping pattern may also be updated. When the frequency channel hopping pattern is not updated and the communication channel scheduled for frequency hopping is unusable, for example, the next communication channel scheduled for frequency hopping may be used.

[0093] In step S100, the master device 20 determines the slave device 30 to be the object of channel mapping control according to the communication state of the wireless communication with each slave device 30. In the channel mapping control, as described above, based on the result of the deletion determination of the communication channel in step S70 and the result of the recovery determination of the deleted communication channel in step S80, a channel map is prepared in step S90 in such a way that only the communication channels that ensure a certain communication quality are included in the channel map. The slave device 30 to be the object of the channel mapping control is sent a channel map from the master device 20 in the channel map sending process of step S120 described later. When the slave device 30 receives a new channel map, it updates the channel map it has to the received channel map. On the contrary, the slave device 30 that is not the object of the channel mapping control is not sent a new channel map from the master device 20. In this case, the slave device 30 continues to use the channel map it has. The process of determining the slave device 30 to be the object of the channel mapping control is periodically implemented. The slave device 30 to be the object of the channel mapping control is updated according to the result.

[0094] Figure 5 Yes means Figure 4 This is a flowchart of an example of a target slave device determination process in step S100 of the flowchart.

[0095] In step S310, the master device 20 acquires, for example, a PER calculated when wirelessly communicating with each slave device 30 in order to understand whether the communication status of the wireless communication with each slave device 30 is good or deteriorated. In step S320, the master device 20 selects one slave device 30 to be determined for the communication status from among the plurality of slave devices 30. And in step S330, the master device 20 determines whether the PER acquired for the selected slave device 30 is less than a threshold value. When the PER is less than the threshold value, it can be considered that the communication status is good. Therefore, in step S340, the master device 20 determines that the communication status of the slave device 30 to be determined for the communication status is "normal". On the other hand, when the PER is greater than the threshold value, the communication status cannot be considered good. Therefore, in step S350, the master device 20 determines that the communication status of the slave device 30 to be determined for the communication status is "abnormal".

[0096] In addition, the parameter used to grasp whether the communication status of the wireless communication with each slave device 30 is good or deteriorated is not limited to PER. For example, as a parameter for grasping the communication status of the wireless communication with each slave device 30, the master device 20 may also use RSSI, SNR / SINR, and BER or PAR. In addition, the master device 20 may also combine multiple parameters to grasp the communication status of the wireless communication with each slave device 30. Furthermore, the parameter used to grasp the communication status may also be a parameter obtained in the wireless communication just before. Alternatively, it may be an average value of multiple parameters obtained in multiple wireless communications. Furthermore, as a parameter for grasping the communication status, the master device 20 may also use the number of communication channels that can be used in the wireless communication corresponding to each slave device 30, that is, the number of communication channels included in the channel mapping corresponding to each slave device 30.

[0097] In step S360, the master device 20 determines whether the determination of the communication status of all the slave devices 30 is completed. If the determination of the communication status of all the slave devices 30 is completed, the master device 20 proceeds to step S370. On the other hand, if the determination of the communication status of all the slave devices 30 is not completed, the master device 20 returns to step S320 and selects a slave device 30 whose communication status has not been determined.

[0098] In step S370, the master device 20 determines whether the communication status of all the slave devices 30 is determined to be "normal" through the processing of the above-mentioned steps S320 to S360. When the communication status of all the slave devices 30 is determined to be "normal", the master device 20 proceeds to step S380. On the other hand, when the communication status of not all the slave devices 30 is determined to be "normal" but the communication status of some of the slave devices 30 is determined to be "abnormal", the master device 20 proceeds to step S390.

[0099] In step S380, the master device 20 determines all slave devices 30 as slave devices 30 to be subject to channel mapping control. On the other hand, in step S390, the master device 20 determines the slave device 30 whose communication status is determined to be "abnormal" as the slave device 30 to be subject to channel mapping control.

[0100] Return to Figure 4 In step S110, the main device 20 determines whether Figure 4The master device 20 determines whether the slave device 30 that performs wireless communication in the communication sequence shown in the flowchart is an implementation target of the channel mapping control. If the slave device 30 is an implementation target of the channel mapping control, the master device 20 enters the channel mapping transmission process of step S120. On the other hand, if the slave device 30 is not an implementation target of the channel mapping control, the master device 20 skips the channel mapping transmission process of step S120. Therefore, a new channel mapping is not transmitted to the slave devices 30 other than the implementation targets of the channel mapping control.

[0101] Figure 6 Yes means Figure 4 This is a flowchart of an example of the channel mapping transmission processing of step S120 of the flowchart.

[0102] In the first step S410, the master device 20 determines whether all the slave devices 30 are the objects of the channel mapping control. If all the slave devices 30 are the objects of the channel mapping control, the master device 20 proceeds to step S420. On the other hand, if all the slave devices 30 are not the objects of the channel mapping control, the master device 20 proceeds to step S430. In step S420, the master device 20 sets the transmission cycle of the channel mapping, in other words, the update cycle of the sharing of the channel mapping to the longest. Specifically, the master device 20 sets the transmission cycle of the channel mapping to a cycle that is greater than the number of all the slave devices 30. On the other hand, in step S430, the master device 20 sets the transmission cycle of the channel mapping to be shorter than the transmission cycle of step S420. Specifically, the master device 20 sets the transmission cycle of the channel mapping to be shorter than the transmission cycle of the channel mapping when all the slave devices 30 are set as the objects of the channel mapping control and to be a transmission cycle greater than the number of the slave devices 30 that are the objects of the channel mapping control.

[0103] Figure 7 1 is a timing chart showing an example of the timing of updating the channel mapping of each slave device 30 when all slave devices 30 are set as the implementation targets of the channel mapping control. Figure 7 As shown, in this embodiment, in order to distribute the processing load for sharing channel mapping in the master device 20, that is, the processing load for sending new channel mappings from the master device 20 to each slave device 30, the master device 20 staggers the transmission period of the channel mapping (the timing of implementing the sharing of the channel mapping) in each slave device 30. Figure 7In the example shown, the master device 20 wirelessly communicates with six slave devices 30. In the initial communication cycle (communication event), the master device 20 sends a channel mapping to the slave device 30 of "S1". After that, the master device 20 sends a channel mapping to the slave device 30 of "S2" in the second communication cycle (communication event), sends a channel mapping to the slave device 30 of "S3" in the third communication cycle (communication event), sends a channel mapping to the slave device 30 of "S4" in the fourth communication cycle (communication event), sends a channel mapping to the slave device 30 of "S5" in the fifth communication cycle (communication event), and sends a channel mapping to the slave device 30 of "S6" in the sixth communication cycle (communication event).

[0104] In addition, in each communication cycle (communication event), as described above, the master device 20 communicates with the slave devices 30 of "S1" to "S6" in the divided sub-communication events. Therefore, for example, in the initial communication cycle (communication event), during the sub-communication event with the slave device 30 of "S1", the master device 20 communicates data with the slave device 30 of "S1" and also transmits the channel mapping.

[0105] However, the master device 20 does not need to stagger the channel mapping transmission period in each slave device 30. For example, in a case where the control device (processor) has the processing capability to perform the channel mapping transmission processing of more than two slave devices 30 in the same communication event, the channel mapping transmission processing of a part (for example, two) of the slave devices 30 may be performed in the same communication event. That is, the timing of implementing the channel mapping transmission processing may not be set as a communication event that is different for each slave device 30, but it may be dispersed at multiple times (multiple communication events) and the channel mapping transmission processing performed on more than two grouped slave devices 30 may be performed at the same time (in the same communication event). In this case, when, for example, the channel mapping transmission period is set to the longest, the channel mapping transmission period is set to a period greater than the number of groups of slave devices 30.

[0106] In such Figure 7In the case where the channel mapping transmission period is staggered among the slave devices 30 as in the example shown, the master device 20 sets the channel mapping transmission period every six communication cycles in such a manner that the channel mapping transmission process is not performed on two or more slave devices 30 at the same time (in the same communication event). However, six communication cycles are just an example, and the channel mapping transmission period can be a period greater than the number of slave devices 30 that are the objects of the channel mapping control. Alternatively, in the case where the channel mapping transmission process is to be performed on two or more slave devices 30 at the same time, the channel mapping transmission period can be a period greater than the number of groups of slave devices 30 that perform the channel mapping transmission process at the same time.

[0107] Figure 8 1 is a timing chart showing an example of the timing of updating the channel mapping of each slave device 30 when a communication state is abnormal and a part of the slave devices 30 are set as the objects of implementation of the channel mapping control. Figure 8 In the example shown, four slave devices 30, "S2" to "S5", are the objects of channel mapping control. Figure 8 In the example shown, Figure 7 Similarly to the example shown, in order to stagger the transmission period of the channel mapping to each slave device 30, the master device 20 transmits the channel mapping to the slave device 30 of "S2" in the first communication cycle (communication event). Thereafter, the master device 20 transmits the channel mapping to the slave device 30 of "S3" in the second communication cycle (communication event), transmits the channel mapping to the slave device 30 of "S4" in the third communication cycle (communication event), and transmits the channel mapping to the slave device 30 of "S5" in the fourth communication cycle (communication event). Figure 8 In the example shown, when the transmission period of the channel mapping is staggered in each slave device 30, the transmission period of the channel mapping is set to five communication periods in such a way that the transmission process of the channel mapping is not performed on more than two slave devices 30 at the same time (in the same communication event). In addition, five communication periods are an example, and the transmission period of the channel mapping only needs to be shorter than the transmission period of the channel mapping when all the slave devices 30 are set as the implementation objects of the channel mapping control and the number of transmission periods is greater than the number of slave devices 30 that are the implementation objects of the channel mapping control. Alternatively, the transmission period of the channel mapping only needs to be shorter than the transmission period of the channel mapping when all the slave devices 30 are set as the implementation objects of the channel mapping control and the number of transmission periods is greater than the number of groups of slave devices 30 that perform the channel mapping transmission process at the same time.

[0108] In this embodiment, if Figure 7 , 8As shown in the example, when the number of slave devices 30 determined as the objects of implementation of channel mapping control is small, the transmission period of channel mapping (the period for implementing sharing of channel mapping) is set shorter than when the number of slave devices 30 determined as the objects of implementation of channel mapping control is large. As a result, the timing of implementing sharing of channel mapping can be advanced in all slave devices 30 determined as the objects of implementation of channel mapping control. As a result, the communication state of the slave device 30 whose communication state has deteriorated can be improved at an early stage. In this way, the effect of channel mapping control can be improved.

[0109] exist Figure 7 , Figure 8 In the example shown in the timing diagram of , the channel map transmission period is scheduled in such a way that the channel map is transmitted to one slave device 30 in each communication event. Figure 6 In step S440 of the flowchart, the channel mapping prepared in step S90 is sent to the slave device 30 whose transmission period of the channel mapping has arrived. The corresponding slave device 30 receives the channel mapping in step S510. If the slave device 30 receives the channel mapping in step S510, in step S520, in order to confirm whether the channel mapping is correctly received, for example, a checksum determination is performed based on the error detection code attached to the received channel mapping. In the case where the slave device 30 determines that the channel mapping is not correctly received based on the checksum determination result in the processing of step S520, for example, in step S530, a signal indicating that the channel mapping is not correctly received or a signal requesting the channel mapping to be sent again is sent. On the other hand, in the case where the slave device 30 determines that the channel mapping is correctly received in the processing of step S520, the channel mapping it has is updated to the newly received channel mapping. And, in step S530, a reception confirmation signal (Ack signal) of the channel mapping is sent to the master device 20.

[0110] The master device 20 receives the Ack signal in step S450. In step S460, the master device 20 performs, for example, a checksum determination based on the error detection code included in the received Ack signal in step S460 in order to confirm whether the Ack signal is correctly received. In the following step S470, the master device 20 determines whether to perform a process for retransmission within the same communication event when it is determined that the Ack signal is not correctly received, or when the self device 30 receives a signal indicating that the channel map is not correctly received or a signal requesting to retransmit the channel map. For example, the master device 20 can decide to retransmit when there is a margin to the extent of retransmission before the end time of this communication event (sub-communication event), and decide not to retransmit when there is no margin. In step S470, the master device 20 performs the process from step S440 again when it is determined to retransmit. When it is determined that the Ack signal is correctly received or when it is determined not to retransmit in step S470, the master device 20 ends the channel map transmission process.

[0111] (Second Embodiment)

[0112] Next, a wireless communication system 10 according to a second embodiment of the present disclosure will be described with reference to the drawings. The wireless communication system 10 according to this embodiment has the same configuration as the wireless communication system 10 according to the first embodiment, and therefore description of the configuration will be omitted.

[0113] In the wireless communication system 10 of the first embodiment, the communication state of the wireless communication with each slave device 30 is divided into "normal" and "abnormal" according to the comparison between PER and a threshold value. And, when the channel mapping control is performed on the slave device 30 whose communication state is determined to be "abnormal", the transmission period of the channel mapping is made shorter than the transmission period of the channel mapping when the communication state of all the slave devices 30 is determined to be "normal". In contrast, in the wireless communication system 10 of the second embodiment, the communication state of the wireless communication with each slave device 30 is divided into three or more stages including "normal", "temporary communication interruption" and "continuous communication interruption" according to the length of the communication interruption period, and the transmission period of the channel mapping is more appropriately controlled according to each divided communication state.

[0114] Below, refer to Fig. 9 and Fig.10 The flowchart of the present embodiment is used to illustrate the object slave device determination processing for determining the slave device 30 that is the implementation object of the channel mapping control and the channel mapping sending processing for sending the channel mapping to the slave device 30 that is the implementation object.

[0115] Fig. 9 The object slave device determination process of the second embodiment shown in the flowchart is relative to Figure 5 In the first embodiment shown in the flowchart of the object from the device determination process, the processes of steps S330, S350 and S390 are deleted, and the processes of steps S332, S352, S354, S356, S392, S394, and S396 are added instead. Fig. 9 The flow chart shows the object slave device determines the processing and Figure 5 There is no difference in the object slave device determination process shown in the flowchart of . Therefore, the following description focuses on the points different from the first embodiment.

[0116] exist Fig. 9 In the object slave device determination process shown in the flowchart of , it is determined in step S332 whether the communication interruption period is less than the first threshold value. The communication interruption period is defined as, for example, a period during which data packet errors (or bit errors: Bit error) occur continuously. Therefore, the communication interruption period can be detected, for example, by a timer that starts timing when the initial data packet error is detected and is reset when the data packet is received normally. If the communication interruption period is less than the first threshold value, the communication state can be regarded as normal. Therefore, the master device 20 determines in step S340 that the communication state of the object slave device 30 is "normal".

[0117] On the other hand, when the communication interruption period is greater than the first threshold, the master device 20 proceeds to step S352. In step S352, the master device 20 further determines whether the communication interruption period is less than the second threshold. When the communication interruption period exceeds the first threshold and is less than the second threshold, the communication state of the wireless communication with the slave device 30 deteriorates, but the degree of deterioration can be regarded as mild. Therefore, when the communication interruption period is less than the second threshold, the master device 20 determines the communication state of the wireless communication of the slave device 30 to be determined as a "temporary communication interruption" state indicating mild deterioration in step S354. However, when the communication interruption period is greater than the second threshold, the communication state of the wireless communication with the slave device 30 deteriorates, and the degree of deterioration can be regarded as severe. Therefore, when the communication interruption period is greater than the second threshold, the master device 20 determines the communication state of the wireless communication of the slave device 30 to be determined as a "continuous communication interruption" state indicating severe deterioration in step S356.

[0118] In addition, the degree of deterioration of the communication status can be determined by comparing the communication quality data such as PER, BER, PAR, RSSI, SNR / SINR, etc. representing the communication quality of the wireless communication of each slave device 30 with multiple thresholds, in addition to the comparison between the above-mentioned communication interruption period and the first threshold and the second threshold.

[0119] And, in Fig. 9 In the target slave device determination process shown in the flowchart of , if the communication status of all the slave devices 30 is not determined to be "normal" in step S370, the process of step S392 is executed. In step S392, the master device 20 determines whether there is a slave device 30 in the "continuous communication interruption" state indicating a serious deterioration of the communication status. In the case where there is no slave device 30 in the "continuous communication interruption" state, that is, in the case of only a slave device 30 in the "temporary communication interruption" state indicating a slight deterioration of the communication status, the master device 20 proceeds to step S394. On the other hand, in the case of a slave device 30 in the "continuous communication interruption" state, the master device 20 proceeds to step S396.

[0120] In step S394, the master device 20 determines the slave device 30 in the "temporary communication interruption" state as the target of channel mapping control. On the other hand, in step S396, the master device 20 determines the slave device 30 in the "permanent communication interruption" state as the target of channel mapping control.

[0121] Here, in this embodiment, as in the first embodiment, when the communication status of all slave devices 30 is "normal", Figure 7 The transmission period of the channel mapping is set to the longest as shown in the example of the timing diagram of FIG. 3. Furthermore, when the communication state of at least one slave device 30 is in the "temporary communication interruption" state, as shown in FIG. Figure 8 The transmission period of the channel mapping is set to be shorter than the longest transmission period, as in the example shown in the timing diagram of . In the transmission period set to be short, for example, in order not to simultaneously send channel mapping to more than two slave devices 30 in the same communication event, the number of slave devices 30 that can be set as the implementation object of the channel mapping control is limited. When the limited number is set to the first number, in the case where the number of slave devices 30 in the "temporary communication interruption" state is less than the first number, the slave devices 30 with relatively poor communication status can also be added as the implementation objects of the channel mapping control until the first number is reached. Conversely, for example, in the case where the number of slave devices 30 in the "temporary communication interruption" state is more than the first number, the slave devices 30 with relatively good communication status can also be excluded from the implementation objects of the channel mapping control until the first number is reached. In addition, the communication status of each slave device 30 can be sorted based on the above-mentioned communication quality data and / or the number of communication channels that can be used for wireless communication.

[0122] In addition, when the communication state of at least one slave device 30 is in the "persistent communication interruption" state, the transmission cycle of the channel mapping is set to be shorter than the longest transmission cycle. In addition, the transmission period of the channel mapping is set in a manner that the channel mapping is transmitted to the slave device 30 as the implementation object of the channel mapping control in the same communication event, and the details are described later. Therefore, according to the relationship between the processing load required for transmitting the channel mapping in the same communication event and the processing capacity of the control device (processor) used to process it, the number of slave devices 30 that can be set as the implementation object of the channel mapping control is limited. When the limited number is set to the second number, when the number of slave devices 30 in the "persistent communication interruption" state is less than the second number, the slave devices 30 with relatively poor communication states can also be added as the implementation objects of the channel mapping control until the second number is reached. Conversely, for example, when the number of slave devices 30 in the "persistent communication interruption" state is more than the second number, the slave devices 30 with relatively good communication states can also be excluded from the implementation objects of the channel mapping control until the second number is reached.

[0123] Fig.10 The channel mapping transmission processing of the second embodiment shown in the flowchart is relative to Figure 6 As for the channel mapping transmission process of the first embodiment shown in the flowchart of , the process of step S430 is deleted, and the processes of steps S432, S434, and S436 are added instead. Fig.10 The channel mapping transmission process shown in the flowchart and Figure 5 There is no difference in the channel mapping transmission process shown in the flowchart of . Therefore, the following description focuses on the differences from the first embodiment.

[0124] exist Fig.10 In the channel mapping transmission process shown in the flowchart of , when it is determined in step S410 that all the slave devices 30 are not the implementation objects of the channel mapping control, the master device 20 performs the process of step S432. In step S432, the master device 20 determines whether the slave devices 30 that are the implementation objects of the channel mapping control include the slave devices 30 in the "continuous communication interruption" state. When it is determined that the slave devices 30 that are the implementation objects of the channel mapping control do not include the slave devices 30 in the "continuous communication interruption" state, that is, only the slave devices 30 in the "temporary communication interruption" state, the master device 20 proceeds to step S434. On the other hand, when it is determined that the slave devices 30 that are the implementation objects of the channel mapping control include the slave devices 30 in the "continuous communication interruption" state, the master device 20 proceeds to the process of step S436.

[0125] In step S434, the master device 20 makes the transmission period of the channel map different in each slave device 30 that is the implementation target of the channel map control, and sets the transmission cycle of the channel map to be shorter than the transmission cycle of step S420. The specific setting example of the transmission cycle is the same as that of the first embodiment described above. Therefore, the transmission period of the channel map to each slave device 30 that is the implementation target of the channel map control is different from that of the master device 20. Figure 8 The sending period is the same as shown in the timing diagram.

[0126] On the other hand, in step S436, the master device 20 sets the transmission period of the channel map to the same period in each slave device 30 that is the implementation object of the channel map control, and sets the transmission cycle of the channel map to be shorter than the transmission cycle of step S420. This transmission cycle can be the same as the transmission cycle of step S434, or it can be shorter than it. Fig.11 The timing chart of 430 shows an example of the timing of transmitting the channel map of each slave device 30 when the transmission period and transmission cycle of the channel map are set in step S436.

[0127] exist Fig.11 In the example shown, three slave devices 30, "S3" to "S5", are the objects of channel mapping control. Fig.11 In the example shown, Figure 7 , 8 The difference from the example shown is that the slave device 30 for "S3" to "S5" transmits the channel mapping in the same communication event (communication cycle 1, communication cycle 6, communication cycle 11). In addition, the transmission cycle of the channel mapping is five communication cycles, which is different from Figure 8 Thus, even if the transmission period is the same, by setting the transmission period of the channel mapping to be the same in the multiple slave devices 30 that are the objects of the channel mapping control, the transmission timing of the channel mapping can be advanced in all the multiple slave devices 30.

[0128] As mentioned above, although the preferred embodiment of the present disclosure has been described, the present disclosure is not limited to the above-mentioned embodiment at all, and can be implemented with various modifications within the scope not departing from the gist of the present disclosure.

[0129] Finally, this specification discloses the following multiple technical concepts and their multiple combinations. The following multiple technical concepts are suitable not only for the wireless communication system 10, but also for the wireless communication method and the wireless communication program.

[0130] (Technical Thought 1)

[0131] A wireless communication system is a system in which a master device (20) performs wireless communication with a slave device (30) via a communication channel selected sequentially from a plurality of communication channels, wherein:

[0132] There are multiple slave devices, and the master device performs wireless communication with each of the multiple slave devices.

[0133] A wireless communication system comprising at least one of (i) a circuit and (ii) a processor having a memory storing a computer program code,

[0134] At least one of a circuit and a processor with a memory enables the wireless communication system to implement:

[0135] a communication channel determination unit (S70, S80, S90) which, when the master device performs wireless communication with the plurality of slave devices, determines the communication quality of each communication channel for each of the slave devices, and determines a communication channel for wireless communication based on the determination result of the communication quality of each communication channel;

[0136] a channel mapping sharing unit (S120) for transmitting a channel mapping indicating the communication channel determined by the communication channel determining unit from the master device to the corresponding slave device so that the master device and the corresponding slave device share the channel mapping;

[0137] a slave device determining unit (S100) for determining the slave device to be the target of the channel map sharing unit to implement the channel map sharing, based on the communication status of the wireless communication between the master device and each of the plurality of slave devices; and

[0138] The timing changing unit (S420, S430, S434, S436) advances the timing of sharing the channel mapping by the channel mapping sharing unit among all the determined slave devices when the number of the slave devices determined by the slave device determining unit is small, compared to a case where the number of the determined slave devices is large.

[0139] (Technical Thought 2)

[0140] According to the wireless communication system described in technical idea 1, when the communication status of the wireless communication with at least one of the slave devices deteriorates, the slave device determination unit determines a smaller number of the slave devices than the total number of the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit, compared to a case where the communication status of the wireless communication with all the slave devices is good.

[0141] (Technical Thought 3)

[0142] The wireless communication system according to technical idea 2, wherein the slave device determination unit determines the small number of slave devices from among the slave devices having a large degree of deterioration in communication status.

[0143] (Technical Thought 4)

[0144] A wireless communication system according to any one of technical ideas 1 to 3, wherein, when the communication state of the wireless communication with at least one of the slave devices is a first communication state indicating that the communication state has deteriorated, the slave device determination unit determines a first number of slave devices including the at least one slave device and which is less than the number of all the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit.

[0145] (Technical Thought 5)

[0146] According to the wireless communication system described in Technical Concept 4, the slave device determination unit determines the second number of slave devices including the at least one slave device and less than the first number as the objects of sharing of the channel mapping by the channel mapping sharing unit when the communication state of the wireless communication with at least one of the slave devices is a second communication state that is worse than the first communication state.

[0147] (Technical Thought 6)

[0148] The wireless communication system according to technical idea 4 or 5, wherein the slave device determination unit determines the deterioration of the communication state between the master device and the plurality of slave devices based on a period during which communication is interrupted.

[0149] (Technical Thought 7)

[0150] The wireless communication system according to any one of technical concepts 1 to 6, wherein the channel map sharing unit periodically causes the master device and the corresponding slave device to share the latest channel map,

[0151] When the number of the slave devices determined by the slave device determination unit is small, the timing change unit advances the timing at which the channel mapping sharing unit implements the sharing of the channel mapping among all the determined slave devices by shortening the period for implementing the sharing of the channel mapping compared to a case where the number of the slave devices determined is large.

[0152] (Technical Thought 8)

[0153] A wireless communication system according to any one of technical ideas 1 to 7, wherein, when the number of the slave devices determined by the slave device determination unit is large, the timing changing unit shifts the timing at which the channel mapping sharing unit implements sharing of the channel mapping for the determined multiple slave devices to multiple timings; on the other hand, when the number of the slave devices determined by the slave device determination unit is small, the channel mapping sharing unit implements sharing of the channel mapping for the determined multiple slave devices at the same time, thereby advancing the timing at which the channel mapping sharing unit implements sharing of the channel mapping in all the determined slave devices.

[0154] (Technical Thought 9)

[0155] A wireless communication system according to any one of technical ideas 1 to 8, wherein the slave device determination unit determines all of the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit when the master device is in a communication state capable of normally conducting wireless communications with a plurality of the slave devices respectively.

[0156] (Technical Thought 10)

[0157] The wireless communication system according to technical idea 9, wherein the channel map sharing unit periodically causes the master device and the corresponding slave device to share the latest channel map,

[0158] When the slave device determination unit determines all the slave devices as objects for implementing the sharing of the channel mapping by the channel mapping sharing unit, the timing change unit delays the timing for implementing the sharing of the channel mapping by the channel mapping sharing unit in all the determined slave devices by setting the period for implementing the sharing of the channel mapping to the longest.

[0159] (Technical Thought 11)

[0160] A wireless communication system according to technical idea 9 or 10, wherein, when the slave device determination unit determines all the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit, the timing changing unit shifts the timing for sharing the channel mapping by the channel mapping sharing unit for all the determined slave devices to a plurality of timings, thereby dispersing the processing load for sharing the channel mapping.

[0161] (Technical Thought 12)

[0162] A wireless communication system according to any one of technical ideas 1 to 11, wherein the slave device determination unit uses at least one of a packet error rate (PER), a bit error rate (BER), a data packet arrival rate (PAR), a received signal strength indication (RSSI), a signal-to-noise ratio (SNR), and a signal-to-interference-plus-noise ratio (SINR) when the master device performs wireless communications with a plurality of the slave devices respectively, to determine the slave device that becomes the object of sharing the channel mapping implemented by the channel mapping sharing unit.

[0163] (Technical Thought 13)

[0164] A wireless communication system according to any one of technical concepts 1 to 11, wherein the slave device determination unit uses the number of communication channels that can be used in wireless communication of each of the slave devices to determine the slave device that becomes the object of sharing the channel mapping implemented by the channel mapping sharing unit.

[0165] (Technical Thought 14)

[0166] The wireless communication system according to any one of technical concepts 1 to 13, wherein the determination of the slave device to be the target of sharing the channel mapping by the slave device determination unit is periodically updated.

[0167] In this disclosure, the term "processor" is a single or multiple hardware processors configured to execute program code (i.e., one or more instructions of a program). In other words, a "processor" is one or more programmable hardware devices. For example, a "processor" is a general-purpose or special-purpose processor, which can be a CPU, a microprocessor, and a PLD such as an FPGA, but is not limited thereto.

[0168] In the present disclosure, the term "memory" refers to one or more hardware memories configured to record computer program code and / or data in a manner that can be accessed by a processor. "Memory" can be implemented by memory technologies such as SRAM, SDRAM, non-volatile / flash memory, or other types of memory. Computer program code is recorded on the memory and can be executed by the processor to enable the processor to implement the various functions described above.

[0169] In this disclosure, the term "circuit" refers to a single or multiple hardware logic circuits configured to implement the aforementioned functions. In other words (and in contrast to "processor"), a "circuit" refers to one or more non-programmable circuits. For example, a "circuit" can be an IC such as an ASIC or other type of non-programmable circuit.

[0170] In the present disclosure, the expression "at least one of the circuit and the processor" should be interpreted as a disjunction (logical OR) and should not be interpreted as at least one circuit and at least one processor. Therefore, in the present disclosure, the expression "at least one of the circuit and the processor enables the wireless communication system to perform functions" should be understood as: (i) only the circuit enables the wireless communication system to perform all functions; (ii) only the processor enables the wireless communication system to perform all functions; or (iii) the circuit enables the wireless communication system to perform a part of the functions and the processor enables the wireless communication system to perform the remaining functions. For example, in the case of (iii) above, functions A and B among all functions A to C can be implemented by the circuit and the remaining function C can be implemented by the processor.

[0171] The control unit and method described in the present disclosure can be implemented by a special-purpose computer, which is provided by constituting a processor and a memory programmed in a manner to execute one or more functions embodied by a computer program. Alternatively, the control unit and method described in the present disclosure can also be implemented by a special-purpose computer, which is provided by constituting a processor using one or more special-purpose hardware logic circuits. Alternatively, the control unit and method described in the present disclosure can also be implemented by one or more special-purpose computers consisting of the following combination, which refers to a combination of a processor and a memory programmed in a manner to execute one or more functions and a processor consisting of one or more hardware logic circuits. In addition, the computer program can also be stored as an instruction executed by a computer in a non-temporary tangible storage medium that can be read by the computer.

[0172] Here, the flowchart or the processing of the flowchart recorded in this application is composed of multiple sections (or steps), and each section is expressed as S10, for example. Furthermore, each section can be divided into multiple sub-sections, and on the other hand, multiple sections can also be combined into one section. Furthermore, each section thus constructed can be referred to as a device, a module, or a means.

[0173] The present disclosure is described based on the embodiments, but it should be understood that the present disclosure is not limited to these embodiments and structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and forms, as well as other combinations and forms in which only one element, more than one element, or less than one element are included, also fall within the scope and thought of the present disclosure.

Claims

1. A wireless communication system, wherein a master device performs wireless communication with a slave device via a communication channel selected sequentially from a plurality of communication channels, characterized in that: There are multiple slave devices, and the master device performs wireless communication with each of the multiple slave devices. The wireless communication system comprises: a communication channel determination unit that, when the master device performs wireless communication with the plurality of slave devices, determines the communication quality of each communication channel for each slave device, and determines a communication channel for wireless communication based on the determination result of the communication quality of each communication channel; a channel map sharing unit that transmits a channel map indicating the communication channel determined by the communication channel determination unit from the master device to the corresponding slave device so that the master device and the corresponding slave device share the channel map; a slave device determining unit that determines the slave device to be the target of the channel map sharing unit to implement the channel map sharing, based on the communication status of the wireless communication between the master device and each of the plurality of slave devices; as well as A timing changing unit, which, when the number of the slave devices determined by the slave device determining unit is small, advances the timing of sharing the channel mapping by the channel mapping sharing unit among all the determined slave devices compared to a case where the number of the determined slave devices is large.

2. The wireless communication system according to claim 1, characterized in that: When the communication status of the wireless communication with at least one of the slave devices deteriorates, the slave device determination unit determines a smaller number of the slave devices than the total number of the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit, compared to a case where the communication status of the wireless communication with all the slave devices is good.

3. The wireless communication system according to claim 2, characterized in that: The slave device determination unit determines the small number of slave devices from among the slave devices having a large degree of deterioration in communication status.

4. The wireless communication system according to claim 1, characterized in that: When the communication state of the wireless communication with at least one of the slave devices is a first communication state indicating that the communication state has deteriorated, the slave device determination unit determines a first number of slave devices including the at least one slave device and which is less than the number of all the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit.

5. The wireless communication system according to claim 4, characterized in that: When the communication state of the wireless communication with at least one of the slave devices is a second communication state that is worse than the first communication state, the slave device determination unit determines the second number of slave devices including the at least one slave device and which is less than the first number as objects for sharing the channel mapping by the channel mapping sharing unit.

6. The wireless communication system according to claim 4, characterized in that: The slave device determination unit determines deterioration of the communication state between the master device and the plurality of slave devices based on a period during which communication is interrupted.

7. The wireless communication system according to any one of claims 1 to 5, characterized in that: The channel map sharing unit periodically enables the master device and the corresponding slave device to share the latest channel map. When the number of the slave devices determined by the slave device determination unit is small, the timing change unit advances the timing at which the channel mapping sharing unit implements the sharing of the channel mapping among all the determined slave devices by shortening the period for implementing the sharing of the channel mapping compared to a case where the number of the slave devices determined is large.

8. The wireless communication system according to any one of claims 1 to 5, characterized in that: When the number of the slave devices determined by the slave device determining unit is large, the timing changing unit shifts the timing at which the channel mapping sharing unit performs sharing of the channel mapping for the multiple slave devices determined to be large to multiple timings. On the other hand, when the number of the slave devices determined by the slave device determining unit is small, the channel mapping sharing unit performs sharing of the channel mapping for the multiple slave devices determined at the same time, thereby advancing the timing at which the channel mapping sharing unit performs sharing of the channel mapping for all the determined slave devices.

9. The wireless communication system according to any one of claims 1 to 5, characterized in that: When the master device is in a communication state in which wireless communication with each of the plurality of slave devices can be performed normally, the slave device determination unit determines all of the slave devices as objects for sharing the channel map by the channel map sharing unit.

10. The wireless communication system according to claim 9, characterized in that: The channel map sharing unit periodically enables the master device and the corresponding slave device to share the latest channel map. When the slave device determination unit determines all the slave devices as objects for implementing the sharing of the channel mapping by the channel mapping sharing unit, the timing change unit delays the timing for implementing the sharing of the channel mapping by the channel mapping sharing unit in all the determined slave devices by setting the period for implementing the sharing of the channel mapping to the longest.

11. The wireless communication system according to claim 9, characterized in that: When the slave device determination unit determines all the slave devices as objects for sharing the channel mapping by the channel mapping sharing unit, the timing change unit shifts the timing for sharing the channel mapping by the channel mapping sharing unit for all the determined slave devices to multiple timings, thereby dispersing the processing load for sharing the channel mapping.

12. The wireless communication system according to any one of claims 1 to 5, characterized in that: The slave device determination unit uses at least one of the packet error rate, bit error rate, data packet arrival rate, received signal strength indication, signal-to-noise ratio, and signal-to-interference-noise ratio when the master device and the plurality of slave devices respectively perform wireless communications to determine the slave device that becomes the object of sharing the channel mapping implemented by the channel mapping sharing unit.

13. The wireless communication system according to any one of claims 1 to 5, characterized in that: The slave device determination unit determines the slave device to be the target of sharing of the channel map by the channel map sharing unit, using the number of communication channels that can be used in wireless communication of each of the slave devices.

14. The wireless communication system according to any one of claims 1 to 5, characterized in that: The determination of the slave device to be the target of sharing the channel mapping by the slave device determination unit is periodically updated.

15. A wireless communication method, which is a method in which a master device performs wireless communication with a slave device via a communication channel selected sequentially from a plurality of communication channels, characterized in that: The master device performs wireless communication with each of the plurality of slave devices. The wireless communication method comprises: a communication channel determination step, in which, when the master device performs wireless communication with the plurality of slave devices, the communication quality of each communication channel is determined for each slave device, and a communication channel for wireless communication is determined based on the determination result of the communication quality of each communication channel; a channel mapping sharing step of transmitting the channel mapping indicating the communication channel determined in the communication channel determination step from the master device to the corresponding slave device so that the master device and the corresponding slave device share the channel mapping; a slave device determining step of determining the slave device to be the object of sharing the channel map in the channel map sharing step according to the communication status of the wireless communication between the master device and each of the plurality of slave devices; and A timing changing step, when the number of the slave devices determined in the slave device determination step is small, advances the timing of implementing the sharing of the channel mapping in the channel mapping sharing step among all the determined slave devices compared to a case where the number of the determined slave devices is large.

16. A persistent computer readable medium having instructions to be executed by at least one processor, characterized in that: The command is used for the master device to perform wireless communication with the slave device via a communication channel selected sequentially from a plurality of communication channels, The master device performs wireless communication with each of the plurality of slave devices. When the command is executed, at least one of the processors is caused to implement: a communication channel determination function, which, when the master device performs wireless communication with the plurality of slave devices, determines the communication quality of each communication channel for each slave device, and determines the communication channel used for wireless communication based on the determination result of the communication quality of each communication channel; a channel mapping sharing function for transmitting a channel mapping representing a communication channel determined by the communication channel determination function from the master device to the corresponding slave device so that the master device and the corresponding slave device share the channel mapping; A slave device determination function for determining the slave device to be the target of the channel mapping sharing function based on the communication status of the wireless communication between the master device and each of the plurality of slave devices; as well as A timing change function, when the number of slave devices determined by the slave device determination function is small, advances the timing of sharing the channel mapping by the channel mapping sharing function among all the determined slave devices compared to a case where the number of slave devices determined is large.

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