COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

Abstract

To provide a communication device, communication method and program which can construct a communication path that can stably communicate with a slave unit when multicast-transmitting information to the plurality of slave units from a master unit.SOLUTION: A communication device in which each instrument made from a master unit and a plurality of slave units constitutes a network of a tree structure having a plurality of classes and which is used to transmit information comprises: a stability index acquisition unit which acquires a stability index being an index of stability of communication between the respective instruments; and a classification unit which classifies each of the plurality of slave units into each layer of the predetermined number of classes on the basis of the stability index between the respective instruments.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a communication device, a communication method, and a program. [Background technology]

[0002] A system has been developed that uses a vibration transducer mounted on a chair to present vibrations in sync with the book or video, improving the sense of realism and the degree to which the impression is retained. This system is used to read picture books to multiple children in classrooms, etc., and the vibration information is transmitted via a wireless system.

[0003] In this type of system, vibration information is sent at the appropriate time from the reader's device to each device where an infant is sitting. Each device where an infant is sitting simultaneously receives this vibration information and vibrates the chair. Since the effect is reduced if the timing of the reading and the vibration are out of sync, it is necessary to transmit the vibration information with little delay.

[0004] In order to transmit vibration information, it is common to transmit and receive waveform signals as audio. Means of transmitting audio signals to multiple terminals include the transmission of analog signals using FM transmitters, digital signals used in wireless microphones, and the transmission of packet data of audio signals by multicast using wireless routers. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 2018-519707 [Patent Document 2] JP 2015-12427 A Summary of the Invention [Problem to be solved by the invention]

[0006] Generally, the transmission of audio signals is optimized for the audible band. Therefore, when vibration information is transmitted as an audio signal, the vibration information, which is in the low frequency band, deteriorates. In addition, the vibration information needs to be dynamically optimized based on the shape of each terminal and the seating state. In that case, it is desirable to transmit the vibration information as editable digital data. However, in the transmission of audio signals by packets, the number of child units can be limited by the upper limit of network traffic with one parent unit. In addition, it is possible to increase the upper limit of the number of child units by installing multiple parent units, but this has the disadvantage that the advance preparation is complicated because it requires the setup of wiring and equipment installation. Furthermore, in a system such as a picture book reading system, the position and number of chairs on which children sit are frequently changed, so it is necessary to easily change the network route.

[0007] There is a method of transmitting data in a daisy chain fashion by wireless devices having both parent and child functions, called a mesh network. For example, in the method described in Patent Document 1, a communication path is dynamically set according to signal quality. In a mesh network system, even if a connection is temporarily cut off, it is common for another communication path to be re-established. However, in a system that requires real-time performance, such as vibration information, a stable network configuration that does not change the communication path in a series of communications is required, rather than a network connection in which the communication path changes dynamically.

[0008] In Patent Document 2, the network connection is stabilized by setting the route according to the wireless electric field strength. However, the electric field strength is significantly affected by the external environment, such as multipath and the presence of obstructions between the parent device and the child device, so it is insufficient to measure the stability of the network connection.

[0009] In view of the above-mentioned problems, the present invention aims to provide a communication device, a communication method, and a program that can establish a communication path that enables stable communication with a child device when multicasting information from a parent device to multiple child devices. [Means for solving the problem]

[0010] A communication device according to one aspect of the present invention transmits information by forming a tree-structured network of a plurality of hierarchical layers including a master unit and a plurality of slave units. Communication Systems Used for The parent unit or the child unit a stability index acquiring unit for acquiring a stability index serving as an index of stability of communication between the devices; Between the parent unit stability index one or more of the slave units having a high stability index relative to the slave units classified in the Kth hierarchical level among the slave units not classified in a hierarchical level are classified into a first hierarchical level, where K is an integer equal to or greater than 1; and one or more of the slave units having a high stability index relative to the slave units classified in the Kth hierarchical level among the slave units not classified in a hierarchical level are classified into a K+1 hierarchical level. A classification unit for classifying the The stability index between a first device and a second device among the communication devices is calculated using at least one of the electric field strength when the second device receives a radio wave transmitted by the first device, the vibration strength when the second device detects a vibration of the first device, and the delay time until the second device detects a sound generated by the vibration. .

[0011] A communication method according to one aspect of the present invention comprises: forming a network of a tree structure having a plurality of hierarchical layers including a master unit and a plurality of slave units; and transmitting information through the network. A communication device that is a master or slave used in a communication system In the communication method, a stability index acquisition unit acquires a stability index serving as an index of stability of communication between the devices, and a classification unit Between the parent unit stability index one or more of the slave units having a high stability index relative to the slave units classified in the Kth hierarchical level among the slave units not classified in a hierarchical level are classified into a first hierarchical level, where K is an integer equal to or greater than 1; and one or more of the slave units having a high stability index relative to the slave units classified in the Kth hierarchical level among the slave units not classified in a hierarchical level are classified into a K+1 hierarchical level. Classified into The stability index between a first device and a second device among the communication devices is calculated using at least one of the electric field strength when the second device receives a radio wave transmitted by the first device, the vibration strength when the second device detects a vibration of the first device, and the delay time until the second device detects a sound generated by the vibration. .

[0012] A program according to one aspect of the present invention transmits information by forming a tree-structured network of a plurality of hierarchical layers including a master unit and a plurality of slave units. Communication Systems Used for The parent unit or the child unit a stability index acquiring means for acquiring a stability index serving as an index of the stability of communication between the devices; Between the parent unit stability index one or more of the slave units having a high stability index relative to the slave units classified in the Kth hierarchical level among the slave units not classified in a hierarchical level are classified into a first hierarchical level, where K is an integer equal to or greater than 1; and one or more of the slave units having a high stability index relative to the slave units classified in the Kth hierarchical level among the slave units not classified in a hierarchical level are classified into a K+1 hierarchical level. to act as a classification tool for classifying A program, wherein the stability index between a first device and a second device among the communication devices is calculated using at least one of an electric field strength when the second device receives a radio wave transmitted by the first device, a vibration strength when the second device detects a vibration of the first device, and a delay time until the second device detects a sound generated by the vibration, It is a program. Effect of the Invention

[0013] According to the present invention, when transmitting information from a parent device to multiple child devices by multicast, a communication path that enables stable communication with the child devices can be established. Therefore, even in a situation where the positions of the multiple child devices are changed, information that requires real-time performance, such as vibration information, can be stably transmitted. [Brief description of the drawings]

[0014] [Figure 1] 1 is an explanatory diagram illustrating an overview of a communication system according to an embodiment of the present invention. [Diagram 2] 2 is a block diagram showing an internal configuration of a master unit in the communication system according to the embodiment of the present invention. FIG. [Diagram 3] 2 is a block diagram showing an internal configuration of a slave unit in the communication system according to the embodiment of the present invention. FIG. [Figure 4] FIG. 4 is an explanatory diagram of calculation of a stability index in the embodiment of the present invention. [Figure 5A] FIG. 1 is an explanatory diagram of a tree-structured network. [Figure 5B] FIG. 1 is an explanatory diagram of a tree-structured network. [Figure 6] 1 is a flowchart showing a process for generating a tree-structured network route in a communication system according to an embodiment of the present invention. [Figure 7] FIG. 2 is an explanatory diagram of stability indexes between devices in a communication system according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram of an overview of a communication system 1 according to an embodiment of the present invention. As shown in FIG. 1, the communication system 1 according to the embodiment of the present invention is composed of a master unit 10 and a plurality of slave units 20-1, 20-2, ..., 20-N (N is any integer). In the following description, when there is no need to distinguish between the slave units 20-1 to 20-N, they may be simply called slave units 20. The communication system 1 is an example of a "communication device."

[0016] Parent unit 10 transmits information by multicast through wireless communication. Child units 20-1 to 20-N simultaneously receive the information from parent unit 10. Here, communication system 1 is a system for reading a book aloud, and the information transmitted by multicast from parent unit 10 to child units 20-1 to 20-N is vibration information.

[0017] A reader 40 holds the parent unit 10 and reads a book aloud. The child units 20-1 to 20-N are mounted inside the chairs 30-1 to 30-N. The children 50-1 to 50-N sit on the chairs 30-1 to 30-N on which the child units 20-1 to 20-N are mounted, and listen to the book read by the reader 40.

[0018] Here, reader 40 inputs vibration information to parent unit 10 at a desired timing. When vibration information is input to parent unit 10, this vibration information is sent to child units 20-1 to 20-N. When child units 20-1 to 20-N receive the vibration information from parent unit 10, they vibrate chairs 30-1 to 30-N in response to the information, and transmit the vibrations to children 50-1 to 50-N.

[0019] 2 is a block diagram showing an internal configuration of master unit 10 in communication system 1 according to an embodiment of the present invention. As shown in FIG. 2, master unit 10 includes an interface unit 11, a speaker 12, a communication unit 13, and a control unit 14.

[0020] The interface unit 11 inputs and outputs various information to and from the control unit 14. The interface unit 11 includes a display, a touch panel, a keyboard, a pointing device, and the like. The reader 40 can operate the interface unit 11 to multicast vibration information to the child units 20-1 to 20-N. The speaker 12 converts an electric signal into an audio signal under the control of the control unit 14. The communication unit 13 performs wireless communication with other devices. The communication unit 13 can be a wireless LAN (IEEE802.11), a Bluetooth (IEEE802.15), or the like. The control unit 14 performs overall control of the parent unit 10. Note that the parent unit 10 can be a general-purpose mobile terminal such as a smartphone or a tablet terminal.

[0021] When the parent unit 10 transmits vibration information to the child units 20-1 to 20-N in accordance with an audio transmission standard, the parent unit 10 frequency-shifts the frequency band of the vibration information so that the vibration information can be transmitted in an audio packet. The audio transmission standard here is a codec (audio compression format) standard such as AAC (Advanced Audio Coding) in Bluetooth and aptX. That is, the frequency band of the vibration information is lower than the frequency band of the audio information, and is subject to frequency restrictions imposed by the audio transmission standard, so it is difficult to transmit the vibration information as is. Therefore, the parent unit 10 shifts the frequency band to a higher frequency by, for example, compressing the vibration information in the time axis, inserts the vibration information into the audio packet, and transmits the information by multicast from the communication unit 13. Note that the method of shifting the vibration information to the higher frequency side is not limited to the method of compressing the time axis, and other methods may be used.

[0022] 3 is a block diagram showing an internal configuration of the slave unit 20 in the communication system 1 according to the embodiment of the present invention. As shown in FIG. 3, the slave unit 20 includes a vibration generating unit 21, an audio microphone 22, a pickup microphone 23, a communication unit 24, and a control unit 25.

[0023] The vibration generating unit 21 is a vibration transducer, and converts an electrical signal into a mechanical vibration under the control of the control unit 25. The voice microphone 22 converts the input voice into an electrical signal and takes it into the control unit 25. The pickup microphone 23 converts the input mechanical vibration into an electrical signal and takes it into the control unit 25. The communication unit 24 performs wireless communication with other devices. The communication unit 24 can also relay data. The communication unit 24 can be a wireless LAN (IEEE802.11), Bluetooth (IEEE802.15), or the like. The control unit 25 performs overall control of the child device 20.

[0024] As described above, the parent device 10 transmits vibration information to the child device 20 by multicast. This vibration information is frequency-shifted to the high frequency side and transmitted in an audio packet. When the child device 20 receives the audio packet including the vibration information, it returns the frequency band of the vibration information to the original frequency band and drives the vibration generating unit 21.

[0025] As will be described later, in this embodiment, a stability index serving as an index of communication stability is calculated from vibration information, audio information, and electric field strength information. Then, based on this stability index, a hierarchical network with a tree structure in which the parent unit 10 is the root node is configured. The control unit 14 on the parent unit 10 side and the control unit 25 on the child unit 20 side have a function of configuring such a hierarchical network with a tree structure. More specifically, the control unit 14 and the control unit 25 have a function of a stability index acquisition unit that acquires a stability index serving as an index of communication stability between each device. Furthermore, the control unit 14 and the control unit 25 have a function of a classification unit that classifies each of the multiple child units 20 into each layer of a predetermined number of layers based on the acquired stability index.

[0026] Next, a network configuration in the communication system 1 according to the embodiment of the present invention will be described.

[0027] In the communication system 1 according to the embodiment of the present invention, vibration information is transmitted by multicast from the master unit 10 to all the slave units 20-1 to 20-N. It is desirable that this vibration information is transmitted to all the slave units 20-1 to 20-N without delay. Furthermore, when transmitting vibration information by multicast from the master unit 10 to all the slave units 20-1 to 20-N, the number of slave units 20-1 to 20-N to which information can be transmitted may be limited by the upper limit of network traffic for one master unit 10. Therefore, in this embodiment, the slave units 20-1 to 20-N are made to function as relays, and the vibration information is transferred as a network configuration.

[0028] When the child devices 20-1 to 20-N are made to function as repeaters, it is important to select which child device is the other party to transfer information. To this end, it is necessary to calculate a stability index that is an index of the stability of communication between devices. It is possible to use electric field strength as the stability index between devices, but electric field strength is significantly affected by external environments such as multipath and obstructions between devices, and is therefore insufficient to measure the stability of network connection. Therefore, in this embodiment, the stability index between devices is calculated as follows.

[0029] 4 is an explanatory diagram of calculation of stability index in this embodiment. Here, it is assumed that the stability of communication is evaluated between two slave units 20-K and 20-L (K and L are arbitrary integers) arranged at arbitrary positions. In this embodiment, the stability of communication is evaluated using the following three types of indexes.

[0030] (a) Vibration information As shown in FIG. 4, two handset units 20-K and 20-L are arranged on the same floor surface 60, and the vibration generating unit 21-K of one handset unit 20-K is activated. In this case, the vibration information of the handset unit 20-K is transmitted through the floor surface 60 and detected by the pickup microphone 23-L of the handset unit 20-L. Since the vibration information is transmitted using the floor surface 60 as a vibration medium, if the pickup microphone 23-L of the handset unit 20-L detects vibration information of a predetermined level or higher, it can be determined that the handset unit 20-K and the handset unit 20-L are on the same floor surface 60. In general, the antenna used for communication of the communication units 24K and 24L of the handset unit 20-K and the handset unit 20-L is omnidirectional in the horizontal direction, but is directional in the vertical direction, and the signal strength in the vertical direction is weak. For this reason, it is considered that the stability of communication is reduced if the handset unit 20-K and the handset unit 20-L are not on the same floor surface. Therefore, the detection result of the intensity of the vibration information serves as an index for evaluating the stability of communication through the antenna.

[0031] (b) Audio information As described above, when the vibration generating unit 21-K of the child device 20-K is activated, the vibration of the child device 20-K travels along the floor surface 60 and becomes audio information through the air, which is picked up by the audio microphone 22-L of the child device 20-L. At this time, the distance between the child device 20-K and the child device 20-L can be estimated by measuring the delay time from when the vibration generating unit 21-K of the child device 20-K is activated until when the audio information is detected by the audio microphone 22-L of the child device 20-L. If the distance between the child device 20-K and the child device 20-L is short, the stability of the communication between the child device 20-K and the child device 20-L is improved. Therefore, detecting the delay time of the audio information is an index for evaluating the stability of the communication depending on the distance between the child device 20-K and the child device 20-L.

[0032] (c) Electric field strength information The radio waves from the communication unit 24-K of the handset 20-K are received by the communication unit 24-L of the handset 20-L. The electric field strength at this time is affected by the surrounding environment. That is, if there is an obstruction between the handset 20-K and the handset 20-L or if multipath occurs, the receiving strength of the radio waves will decrease. Therefore, detecting the electric field strength is an index for evaluating the stability of communication due to the influence of the obstruction between the handset 20-K and the handset 20-L.

[0033] As described above, by detecting the intensity of the vibration information, an evaluation value for the stability of communication via the antenna can be obtained. Let this evaluation value for stability via the antenna be A. Furthermore, by detecting the delay time of the audio information, an evaluation value for the stability of communication depending on the distance between the devices can be obtained. Let this evaluation value for stability depending on distance be D. Furthermore, by detecting the electric field intensity, an evaluation value for the stability of communication depending on the influence of obstructions between the devices can be obtained. Let this evaluation value for stability depending on obstructions be O. From these evaluation values, the stability index S between the devices can be calculated as follows:

[0034]

number

[0035] The stability index S between the parent unit 10 and the child units 20 (20-1 to 20-N) can be calculated using an evaluation value based on audio information as well as an evaluation value based on electric field strength. Of course, if a vibration generating unit or a pickup microphone is provided in the parent unit 10, it is possible to detect vibration information between the parent unit 10 and the child units 20 (20-1 to 20-N) and calculate an evaluation value.

[0036] Next, a network configuration in which information from parent device 10 is received by child devices 20-1 to 20-N will be described.

[0037] When multiple child devices 20-1 to 20-N are connected to one parent device 10, depending on the network configuration, data transmission may not be able to keep up and may be interrupted while waiting for transmission and reception. For this reason, it is desirable to have a tree structure as shown in Figures 5A and 5B. However, as the number of layers increases, a time lag occurs between shallow layers and deep layers, so when real-time performance is required, such as in a reading-aloud system, it is necessary to balance the number of connected child devices 20 and the number of layers.

[0038] 5A and 5B are explanatory diagrams of a tree-structured network configuration. FIG. 5A shows an example of a tree-structured network configured by connecting two child nodes to one parent node. FIG. 5B shows an example of a tree-structured network configured by connecting three child nodes to one parent node. In FIG. 5A and 5B, the root node is indicated by RN. Also, the first layer node is indicated by L1, and the second layer node is indicated by L2.

[0039] In addition, when reading a book aloud, the child units 20-1 to 20-N are mounted on the chairs 30-1 to 30-N as shown in Fig. 1. The chairs 30-1 to 30-N are rearranged as appropriate. Therefore, it is desirable to generate a network path as appropriate according to the arrangement of the child units 20-1 to 20-N.

[0040] When a tree-structured network is configured in the communication system according to this embodiment, the root node RN is the parent device 10, and child devices 20-1 to 20-N are appropriately arranged at other nodes. In a tree-structured network, if the number of child nodes connected to one parent node is C and the number of layers is Depth, the total number of nodes is as follows:

[0041]

number

[0042] Therefore, once an arbitrary number of layers is determined, the maximum number of child nodes connected to one parent node can be calculated from the total number of child devices 20-1 to 20-N used in the system. Once the number of layers and the number of child nodes connected to a parent node are determined, the network route is generated autonomously as follows.

[0043] FIG. 6 is a flowchart showing a process for generating a tree-structured network route in the communication system 1 according to the embodiment of the present invention.

[0044] (Step ST1) Parent unit 10 sends an instruction to child units 20-1 to 20-L to measure the stability index between each device.

[0045] (Step ST2) Parent unit 10 and each of child units 20-1 to 20-L calculate a stability index between each device. As described above, the stability index between each of child units 20-1 to 20-L can be calculated using vibration information, audio information, and electric field strength information. Also, the stability index between parent unit 10 and child units 20-1 to 20-L can be calculated using audio information and electric field strength information.

[0046] (Step ST3) Parent device 10 and each of child devices 20-1 to 20-L receive the stability index between each of the devices obtained by each of the devices.

[0047] (Step ST4) The master unit 10 and each of the slave units 20-1 to 20-L create a table as shown in FIG. 7 from the stability index between each of the devices. FIG. 7 is an explanatory diagram of the stability index between each of the devices in the communication system according to the embodiment of the present invention. This table summarizes the stability index between the master unit 10 and each of the slave units 20-1 to 20-N. For example, S 01 is a stability index between the parent device 10 and the child device 20-1, and S 02 is a stability index between the parent device 10 and the child device 20-2, and S 0N is a stability index between the parent device 10 and the child device 20-N. 12 is a stability index between the slave unit 20-1 and the slave unit 20-2, and S 13 is a stability index between the slave unit 20-1 and the slave unit 20-3, and S 1N is the stability index between the slave unit 20-1 and the slave unit 20-N. Note that "*" means that it is omitted because there is a stability index with the same combination for the other unit. For example, the stability index S between the master unit 10 and the slave unit 20-2 is 02 is the stability index S between the child device 20-2 and the parent device 10. 20 Since the table is the same as the table above, it is indicated by "*." This table may be created by parent device 10 and one of child devices 20-1 to 20-L and shared by each device.

[0048] (Step ST5) The master unit 10 classifies the slave units having a high stability index relative to the master unit 10 into the first hierarchical layer L1 from the table of FIG. 7, and establishes a connection between the master unit 10 and the slave units in the first hierarchical layer L1. That is, from the table of FIG. 7, the stability index S between the master unit 10 and each of the slave units 20-1, 20-2, ..., 20-N is 01 , S 02 , … , S 0N Compare these stability indices S 01 , S 02 , … , S 0N The slave unit corresponding to the one with the highest stability index among them is classified as a slave unit of the first layer L1 and a connection is established.

[0049] (Step ST6) Parent unit 10 and each of child units 20-1 to 20-L determine whether or not the classification has been completed up to the final layer. If it is not the final layer (step ST6: No), the process proceeds to step ST7. If it is the final layer (step ST6: No), the process proceeds to step ST8.

[0050] (Step ST7) The child device 20 in the Kth hierarchical layer (K ​​is an arbitrary number) compares the stability index with the parent device 10 in descending order of the stability index with the child device 20, classifies the child device with the highest stability index with respect to the child device 20 (excluding the child device whose arrangement has already been decided) as a child device in the next hierarchical layer, establishes a connection, and returns the process to step ST6. For example, if the child device 20-2 is classified in the first hierarchical layer L1, the child device 20-2 calculates the stability index S between the child device 20-2 and each child device 20-1, 20-3, ..., 20-N. 12 , S 23 , … , S 2N Compare these stability indices S 12 , S 23 , … , S 2N The child device corresponding to the node with the highest stability index is classified as a child device of the node in the second layer L2 and a connection is established.

[0051] By repeating steps ST6 and ST7, the child devices 20 are classified into layers, and a connection is established between the child devices 20 in each layer.

[0052] (Step ST8) In each child device 20 in the final hierarchy, in order to ensure that there are no remaining combinations with extremely low stability indexes, connections are established between this child device 20 and the higher-level child devices 20 connected to it in order of lowest stability index value.

[0053] In the above description, the child devices 20 in each layer compare the stability index between the child devices 20, classify the child device with the higher stability index for the child device 20 as a child device in the next layer, and establish a connection, thereby autonomously setting the route, but the parent device 10 may also tally up the stability index between each device, and set the route for each layer. Also, a separate terminal may be prepared for tallying up the stability indexes and setting the routes.

[0054] In the above description, the number of hierarchical layers is determined in advance, and the slave units belonging to each layer are classified. However, the present invention is not limited to this. When there is an extreme difference in the stability indexes of the slave units belonging to the same layer, communication may become unstable. As a countermeasure against this, for example, the slave units 20 once classified into the final layer may be classified into multiple layers into groups with high and low stability indexes according to the distribution of the stability indexes. Alternatively, the slave units 20 in the final layer may be connected to the slave units with higher stability indexes in descending order. The remaining slave units 20 (those with low stability indexes with the higher slave units) may be connected to the slave units 20 with higher stability indexes by comparing the stability indexes with the higher slave units and the stability indexes with the slave units 20 in the final layer.

[0055] As described above, in this embodiment, a stability index is calculated based on vibration information, audio information, and electric field strength information. Then, a measurement value of the stability index between each device is obtained, and based on this stability index, each of the multiple devices is classified into each layer of a predetermined number of hierarchical layers. As a result, when transmitting information from a parent device to multiple child devices by multicast, even in a situation where the placement positions of many child devices change, a route can be automatically generated and stable communication with the child devices can be achieved. Also, in this embodiment, a network can be configured by specifying a child device with high stability for each layer.

[0056] The communication system 1 in the above-mentioned embodiment may be realized in whole or in part by a computer. In that case, a program for realizing this function may be recorded in a computer-readable recording medium, and the program recorded in the recording medium may be read into a computer system and executed to realize the function. The term "computer system" as used herein includes hardware such as an OS and peripheral devices. The term "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. The term "computer-readable recording medium" may also include a medium that dynamically holds a program for a short period of time, such as a communication line when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, and a medium that holds a program for a certain period of time, such as a volatile memory inside a computer system that is a server or client in that case. The above-mentioned program may be a program for realizing a part of the above-mentioned function, or may be a program that can realize the above-mentioned function in combination with a program already recorded in the computer system, or may be a program that is realized using a programmable logic device such as an FPGA.

[0057] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and designs that do not deviate from the gist of the present invention are also included. [Explanation of symbols]

[0058] 10... parent unit, 11... interface unit, 12... speaker, 13... communication unit, 14... control unit (stability index acquisition unit) (classification unit), 20... child unit, 21... vibration generation unit, 22... audio microphone, 23... pickup microphone, 24... communication unit, 25... control unit (stability index acquisition unit) (classification unit)

Claims

1. A communication device which is a parent device or a child device used in a communication system in which devices each consisting of a parent device and a plurality of child devices form a tree-structured network consisting of a plurality of hierarchical layers to transmit information, a stability index acquisition unit that acquires a stability index serving as an index of stability of communication between the devices; a classification unit that classifies one or more of the child devices having a high stability index between the child device and the parent device into a first hierarchical level, and classifies one or more child devices having a high stability index between the child device and the child device classified into the Kth hierarchical level among the child devices not classified into a hierarchical level into a K+1 hierarchical level, where K is an integer of 1 or more; Equipped with The stability index between a first device and a second device among the communication devices is calculated using at least one of the electric field strength when the second device receives a radio wave transmitted by the first device, the vibration strength when the second device detects a vibration of the first device, and the delay time until the second device detects a sound generated by the vibration. Communications equipment.

2. A communication method for a communication device that is a parent device or a child device used in a communication system in which devices including a parent device and a plurality of child devices form a tree-structured network consisting of a plurality of hierarchical layers to transmit information, comprising: a stability index acquiring unit acquiring a stability index serving as an index of stability of communication between the devices; a classification unit classifies one or more of the child devices having a high stability index between the child device and the parent device into a first hierarchy, and classifies one or more child devices having a high stability index between the child device and the child device classified into the Kth hierarchy among the child devices not classified into a hierarchy into a K+1 hierarchy, where K is an integer equal to or greater than 1; and the stability index between the first device and the second device among the communication devices is calculated using at least one of the vibration intensity when the second device detects the vibration of the first device and the delay time until the second device detects the sound generated by the vibration in addition to the electric field intensity when the second device receives the radio wave transmitted by the first device. Communication methods.

3. A computer of a communication device which is a parent device or a child device used in a communication system in which each device, which is a parent device and a plurality of child devices, constitutes a tree-structured network consisting of a plurality of hierarchical layers and transmits information, a stability index acquiring means for acquiring a stability index serving as an index of stability of communication between the devices; a classification means for classifying one or more of the child devices having a high stability index between the child device and the parent device into a first hierarchical level, and classifying one or more child devices having a high stability index between the child device and the child device classified into the Kth hierarchical level, among the child devices not classified into a hierarchical level, into a K+1 hierarchical level, where K is an integer of 1 or more; A program that functions as The stability index between a first device and a second device among the communication devices is calculated using at least one of the electric field strength when the second device receives a radio wave transmitted by the first device, the vibration strength when the second device detects a vibration of the first device, and the delay time until the second device detects a sound generated by the vibration. program.

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