JP7649007B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a communication device, a communication method, and a program.

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 retention of impressions. This system is used to transmit vibration information via a wireless system so that picture books can be read to multiple young children in classrooms, etc.

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 there is a mismatch between the reading and the vibration, it is necessary to transmit the vibration information with little delay.

The general method for transmitting vibration information is to send and receive waveform signals as audio. Means for transmitting audio signals to multiple terminals include sending analog signals using an FM transmitter, digital signals used in wireless microphones, and transmitting packet data of audio signals by multicast using a wireless router.

Special table 2018-519707 publication JP 2015-12427 A

Generally, the transmission of audio signals is optimized for the audible range. Therefore, when vibration information is transmitted as an audio signal, the vibration information, which is in the low frequency range, deteriorates. In addition, the vibration information needs to be dynamically optimized based on the shape of each terminal and the seating state. In this 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 be able to easily change the network route.

There is a method of transmitting data in a daisy chain fashion by wireless devices that function as both a master and slave, known as a mesh network. For example, in the method described in Patent Document 1, the communication path is dynamically set depending on the signal quality. In a mesh network system, it is common for another communication path to be re-established even if a connection is temporarily lost. However, in a system that requires real-time performance, such as vibration information, a stable network configuration that does not change the communication path during a series of communications is required, rather than a network connection in which the communication path changes dynamically.

In Patent Document 2, the network connection is stabilized by setting the route based on the wireless electric field strength. Since 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, it is insufficient to measure the stability of the network connection.

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 transmitting information from a parent device to multiple child devices by multicast.

A communication device according to one embodiment of the present invention is a communication device which is a parent device or a child device used in a communication system in which devices consisting of a parent device and multiple child devices form a tree-structured network consisting of multiple hierarchical levels to transmit information, and which comprises: a stability index acquisition unit which acquires a stability index which is an index of the stability of communication between the devices; and a classification unit which classifies one or more child devices which have a high stability index between the parent device and the parent device into a first hierarchical level, and classifies one or more child devices which have a high stability index between the parent device and the child devices which are not classified into a hierarchical level and which are classified into the Kth hierarchical level into a K+1 hierarchical level , where K is an integer greater than or equal to 1. The stability index between a first device and a second device in the communication device is calculated using at least one of the electric field strength when the second device receives radio waves transmitted by the first device, the vibration strength 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 .

A communication method according to one embodiment of the present invention is a communication method for a communication device that is a parent device or a child device used in a communication system in which each device consisting of a parent device and multiple child devices forms a tree-structured network consisting of multiple hierarchical levels to transmit information, wherein a stability index acquisition unit acquires a stability index that is an indicator of the stability of communication between the devices, and a classification unit classifies one or more child devices that have a high stability index between the parent device and the parent device into a first hierarchical level, and classifies one or more child devices that have a high stability index between the parent device and the child device classified into the Kth hierarchical level among the child devices that are not classified into a hierarchical level into a K+1 hierarchical level , and the stability index between a first device and a second device of the communication devices is calculated using at least one of the electric field strength when the second device receives radio waves transmitted by the first device, the vibration strength 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.

A program according to one embodiment of the present invention causes a computer of a communication device, which is a parent device or a child device, used in a communication system in which each device, consisting of a parent device and multiple child devices, forms a tree-structured network consisting of multiple hierarchical levels to transmit information, to function as: a stability index acquisition means for acquiring a stability index that is an index of the stability of communication between the devices; and a classification means for classifying one or more child devices having a high stability index between the parent device and the parent device into a first hierarchical level, and classifying one or more child devices having a high stability index between the parent 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 greater.The stability index between a first device and a second device of the communication devices is calculated using at least one of the electric field strength when the second device receives radio waves transmitted by the first device, the vibration strength 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 .

According to the present invention, when transmitting information from a parent unit to multiple child units by multicast, a communication path that allows stable communication with the child units can be established. Therefore, even in a situation where the respective positions of the multiple child units are changed, it is possible to stably transmit information that requires real-time performance, such as vibration information.

1 is an explanatory diagram illustrating an overview of a communication system according to an embodiment of the present invention. 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. 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. FIG. 4 is an explanatory diagram of calculation of a stability index in the embodiment of the present invention. FIG. 1 is an explanatory diagram of a tree-structured network. FIG. 1 is an explanatory diagram of a tree-structured network. 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. FIG. 2 is an explanatory diagram of stability indexes between devices in a communication system according to an embodiment of the present invention.

Embodiments of the present invention will now 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 an embodiment of the present invention is composed of a parent unit 10 and multiple child units 20-1, 20-2, ..., 20-N (N is any integer). In the following description, when there is no need to distinguish between the child units 20-1 to 20-N, they may simply be referred to as child units 20. The communication system 1 is an example of a "communication device".

The parent unit 10 transmits information by multicast via wireless communication. The child units 20-1 to 20-N simultaneously receive the information from the parent unit 10. Here, the communication system 1 is a system for reading books aloud, and the information transmitted by multicast from the parent unit 10 to the child units 20-1 to 20-N is vibration information.

The 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 in which the child units 20-1 to 20-N are mounted, and listen to the book read by the reader 40.

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

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

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 electrical 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) or Bluetooth (IEEE802.15), for example. The control unit 14 controls the entire parent unit 10. Note that the parent unit 10 can be a general-purpose mobile terminal such as a smartphone or a tablet terminal.

When transmitting vibration information from the parent unit 10 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 refers to a codec (audio compression format) standard such as AAC (Advanced Audio Coding) in Bluetooth or aptX. In other words, 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, making it difficult to transmit the 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 via 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 time axis compression method, and other methods may be used.

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

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 audio microphone 22 converts the input audio into an electrical signal and inputs it into the control unit 25. The pickup microphone 23 converts the input mechanical vibration into an electrical signal and inputs 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) or Bluetooth (IEEE802.15), etc. The control unit 25 controls the entire handset 20.

As described above, vibration information is transmitted by multicast from the parent unit 10 to the child unit 20. This vibration information is frequency shifted to the higher frequency side and transmitted in an audio packet. When the child unit 20 receives the audio packet containing the vibration information, it returns the frequency band of the vibration information to the original frequency band and drives the vibration generating unit 21.

As will be described later, in this embodiment, a stability index that is 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 constructed. 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 constructing 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 that is 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.

Next, we will explain the network configuration of the communication system 1 according to an embodiment of the present invention.

In the communication system 1 according to an embodiment of the present invention, vibration information is transmitted by multicast from the parent unit 10 to all child units 20-1 to 20-N. It is desirable that this vibration information be transmitted to all child units 20-1 to 20-N without delay. Furthermore, when transmitting vibration information by multicast from the parent unit 10 to all child units 20-1 to 20-N, the number of child units 20-1 to 20-N to which information can be transmitted with one parent unit 10 can be limited due to the upper limit of network traffic. Therefore, in this embodiment, the child units 20-1 to 20-N function as repeaters, and transfer the vibration information as a network configuration.

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

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

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

(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.

(c) Electric Field Strength Information 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 reception 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 obstructions between the handset 20-K and the handset 20-L.

As described above, by detecting the strength 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 strength, 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:

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, vibration information can be detected between the parent unit 10 and the child units 20 (20-1 to 20-N) to calculate an evaluation value.

Next, we will explain the network configuration when the child devices 20-1 to 20-N receive information from the parent device 10.

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 like that shown in Figures 5A and 5B. However, as the number of layers increases, a time lag occurs between shallow 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.

FIGS. 5A and 5B are explanatory diagrams of tree-structured network configurations. FIG. 5A shows an example of a tree-structured network formed by connecting two child nodes to one parent node. FIG. 5B shows an example of a tree-structured network formed 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.

When reading a book aloud, as shown in FIG. 1, child devices 20-1 to 20-N are mounted on chairs 30-1 to 30-N. These chairs 30-1 to 30-N can be rearranged as appropriate. Therefore, it is desirable to generate network paths appropriately according to the arrangement of child devices 20-1 to 20-N.

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 placed 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, then the total number of nodes is as follows:

Therefore, once an arbitrary number of hierarchical levels has been 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 hierarchical levels and the number of child nodes connected to a parent node have been determined, the network routes are generated autonomously as follows.

Figure 6 is a flowchart showing the process of generating a tree-structured network route in a communication system 1 according to an embodiment of the present invention.

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

(Step ST2) The parent unit 10 and each child unit 20-1 to 20-L calculate a stability index between each device. As described above, the stability index between each child unit 20-1 to 20-L can be obtained using vibration information, audio information, and electric field strength information. In addition, the stability index between the parent unit 10 and each child unit 20-1 to 20-L can be obtained using audio information and electric field strength information.

(Step ST3) The parent device 10 and each child device 20-1 to 20-L receive the stability index between each device calculated by each device.

(Step ST4) The parent device 10 and each child device 20-1 to 20-L create a table as shown in FIG. 7 from the stability index between each device. FIG. 7 is an explanatory diagram of the stability index between each device in the communication system according to the embodiment of the present invention. This table summarizes the stability index between each device of the parent device 10 and the child devices 20-1 to 20-N. For example, S ₀₁ is the stability index between the parent device 10 and the child device 20-1, S ₀₂ is the stability index between the parent device 10 and the child device 20-2, and S _0N is the stability index between the parent device 10 and the child device 20-N. S ₁₂ is the stability index between the child device 20-1 and the child device 20-2, S ₁₃ is the stability index between the child device 20-1 and the child device 20-3, and S _1N is the stability index between the child device 20-1 and the child device 20-N. Note that "*" means that it is omitted because there is a stability index with the same combination for the other party. For example, the stability index _S02 between the parent unit 10 and the child unit 20-2 is the same as the stability index _S20 between the child unit 20-2 and the parent unit 10, so it is indicated by "*". Also, this table may be created by the parent unit 10 and one of the child units 20-1 to 20-L and shared by each of the devices.

(Step ST5) The parent device 10 classifies the child devices having a high stability index relative to the parent device 10 into the first hierarchical layer L1 from the table in Fig. 7, and establishes a connection between the parent device 10 and the child devices in the first hierarchical layer L1. That is, the parent device 10 compares the stability indexes _S01 , _S02 , ..., _S0N between the parent device 10 and each child device 20-1, 20-2, ..., 20-N from the table in Fig. 7, and classifies the child device having the high stability index among these stability indexes _S01 , _S02 , ..., _S0N as a child device in the first hierarchical layer L1, and establishes a connection.

(Step ST6) The parent unit 10 and each child unit 20-1 to 20-L determine whether or not 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.

(Step ST7) The child device 20 in the Kth hierarchical layer (K is an arbitrary number) compares the stability indexes with the child device 20 in descending order of the stability index with the parent device 10, classifies the child device with the high 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 to the process in step ST6. For example, when the child device 20-2 is classified in the first hierarchical layer L1, the child device 20-2 compares the stability indexes S ₁₂ , S ₂₃ , ..., S _2N between the child device 20-2 and each child device 20-1, 20-3, ..., 20-N, and classifies the child device with the high stability index among these stability indexes S ₁₂ , S ₂₃ , ..., S _2N as a child device of a node in the second hierarchical layer L2, and establishes a connection.

By repeating steps ST6 and ST7, each child device 20 is classified into each hierarchy, and a connection is established between each child device 20 in each hierarchy.

(Step ST8) In each child device 20 in the final hierarchy, in order to prevent any remaining combinations from having an extremely low stability index, a connection is established between this child device 20 and the higher child devices 20 connected to it in ascending order of stability index value.

In the above description, the child devices 20 in each hierarchy compare the stability index between the child devices 20, classify the child devices with higher stability indexes for the child devices 20 in the next hierarchy, and establish a connection, thereby autonomously setting the route; however, the parent device 10 may also tally up the stability indexes between each device, and set the route for each hierarchy. Also, a separate terminal may be provided for tallying up the stability indexes and setting the route.

In the above description, the number of hierarchical layers is determined in advance, and the child devices belonging to each layer are classified. However, this is not limiting. If there is an extreme difference in the stability indexes of multiple child devices belonging to the same layer, communication may become unstable. As a countermeasure, for example, the group of child devices 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 each stability index. Alternatively, each child device 20 in the final layer may be connected to a higher child device in order of the stability index. For the remaining child devices 20 (those with low stability indexes with the higher child devices), the stability index with the higher child device and the stability index with the child device 20 in the final layer may be compared, and the child device 20 with the higher stability index may be connected to the child device 20 with the higher stability index.

As described above, in this embodiment, a stability index is calculated based on vibration information, audio information, and field strength information. Then, the measured values of the stability index between each device are obtained, and based on this stability index, each of the multiple devices is classified into each layer of a predetermined number of hierarchical levels. 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. Furthermore, in this embodiment, a network can be configured by specifying a child device with a high stability for each layer.

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 the computer system and executed to realize the function. Note that the term "computer system" here includes hardware such as an OS and peripheral devices. Furthermore, 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 the computer system. Furthermore, the term "computer-readable recording medium" may include a medium that dynamically holds a program for a short period of time, such as a communication line when transmitting a program 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 such a case. Furthermore, 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.

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment, and includes designs that do not deviate from the gist of the present invention.

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 (3)

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. 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. 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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