Wireless communication terminal and transmission timing control method

Abstract

To appropriately control transmission timing in such a manner that each radio communication terminal in a radio communication network avoids collision even in a situation where a hidden terminal exists, and to improve the success probability thereof.SOLUTION: Each of a plurality of radio communication terminals in a radio communication network defines each of a plurality of phases in a predetermined cycle as packet transmission timing. Each radio communication terminal calculates an overall average phase which is an average value of the plurality of phases of all the radio communication terminal. Further, each radio communication terminal performs phase update processing for updating the plurality of phases thereof in such a manner that the average value of the plurality of phases thereof is close to an overall average phase and the plurality of phases are different among the plurality of radio communication terminals. A noise component is added to the overall average phase so as to decrease a phase update width in the phase update processing. Each radio communication terminal then notifies the other radio communication terminal of the updated phase information through packet transmission.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to transmission timing control in each of a plurality of wireless communication terminals in a wireless communication network. [Background technology]

[0002] With the advent of the IoT era, it is predicted that an increasing number of wireless communication terminals will be used in the future. However, the frequency bands and time that can be allocated to wireless communication terminals are limited, and how to effectively utilize these wireless communication resources is an important issue.

[0003] In recent years, attempts have been made to apply the Kuramoto model to scheduling methods in wireless sensor networks (Non-Patent Document 1). The Kuramoto model is a mathematical model that describes the phenomenon of synchronization between multiple oscillators due to their interaction, such as the synchronization of multiple metronomes on the same board. In scheduling methods based on the Kuramoto model, the transmission timing of each sensor node is likened to a phase. Then, each sensor node observes the phase of other sensor nodes and autonomously updates its own phase, thereby achieving fair and scalable scheduling.

[0004] The following describes the formulas and techniques disclosed in Non-Patent Document 1. Consider N interacting oscillators (N is an integer equal to or greater than 2). The phase θ of each oscillator i (i=1 to N) is i changes according to the following equations (1) and (2).

[0005]

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[0007] The average phase φ is the phase θ of all N oscillators. i is the average value of wi is the natural frequency of node i. r is the order parameter. K is the coupling strength between oscillators. ΔT is the unit time.

[0008] Next, the N oscillators are replaced with N nodes (wireless communication terminals) in the wireless communication network. The packet transmission timing of each node i (i=1 to N) is determined by the phase θ i Each node i calculates its own phase θ i In equation (3), a0 is an initial value between 0 and 1.

[0009]

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[0010] Then, each node i updates its own phase θ i The node j notifies other nodes j (j=1 to N, j≠i) of the information through packet transmission. The node j receives the packet transmitted from the node i and demodulates the received packet to obtain the updated phase θ i In this way, each node i can share the latest phase information and recognize its own phase θ i According to the above formula (3), the phase θ of each node i is i converges to the value shown in the following equation (4).

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[0012] Phase θ of each node i iconverges to be shifted by the differential phase from the average phase φ. The differential phase is a value specific to each node i and differs among the N nodes. This means that the transmission timings of the N nodes do not overlap within a predetermined transmission period but are dispersed. In this way, the N nodes adjust their own phases θ i (Transmission timing) is controlled autonomously and decentralized, and time-division communication is performed.

[0013] The phase θ after convergence shown in equation (4) i The average phase φ in this case is expressed by the following equation (5).

[0014]

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[0015] However, according to the technique described in Non-Patent Document 1, as shown in the above formula (5), the average phase φ after convergence includes a phase specific to the node. Therefore, in a situation where hidden terminals exist, there is a problem that the average phase φ calculated at each node differs for each node. In other words, the technique described in Non-Patent Document 1 cannot deal with the hidden terminal problem.

[0016] Non-Patent Document 2 discloses a technology that enables each node in a wireless communication network to appropriately control transmission timing so as to avoid packet collisions even in a situation where a hidden terminal exists. The technology described in Non-Patent Document 2 will be described in detail later. [Prior art documents] [Non-patent literature]

[0017] [Non-Patent Document 1] U. Yu, H. Choi and J. Lee, “Kuramoto-Desync: Distributed and Fair Resource Allocation in a Wireless Network,” in IEEE Access, Vol.7, pp.104769-104776, 2019 [Non-patent document 2] Ikugata et al., "Kuramoto Model-Based Scheduling Method Considering Hidden Terminals in Wireless Sensor Networks," 2022 IEICE General Conference, B-5-88, Proceedings of the IEICE Communications Conference, vol. 1, p. 399, 2022 Summary of the Invention [Problem to be solved by the invention]

[0018] One object of the present invention is to further improve the technique disclosed in Non-Patent Document 2 and to provide a technique that can increase the probability of successful phase synchronization. [Means for solving the problem]

[0019] A first aspect relates to a wireless communication terminal in a wireless communication network including a plurality of wireless communication terminals. The wireless communication terminal includes a communication controller. The communication controller A process of setting each of a plurality of phases in a predetermined period as a packet transmission timing; A process of calculating an overall average phase which is an average value of a plurality of phases across a plurality of wireless communication terminals; a phase update process for updating the phases of the wireless communication terminals so that an average value of the phases of the wireless communication terminals approaches an overall average phase and the phases differ among the wireless communication terminals; A process of notifying other wireless communication terminals of the updated phase information through packet transmission. is configured to execute The communication controller further adds a noise component to the overall average phase so that the phase update width in the phase update process is reduced, and executes the phase update process using the overall average phase to which the noise component has been added.

[0020] A second aspect relates to a transmission timing control method in each of a plurality of wireless communication terminals in a wireless communication network. The transmission timing control method is a process in which each wireless communication terminal sets a plurality of phases in a predetermined period as packet transmission timings; A process of calculating an overall average phase which is an average value of a plurality of phases across a plurality of wireless communication terminals; a phase update process for updating the plurality of phases of each wireless communication terminal so that an average value of the plurality of phases of each wireless communication terminal approaches an overall average phase and the plurality of phases differ among the plurality of wireless communication terminals; A process of notifying other wireless communication terminals of the updated phase information through packet transmission. Includes. The phase update process includes adding a noise component to the overall average phase so that the phase update width decreases, and the phase update process is then performed using the overall average phase to which the noise component has been added. [Effects of the Invention]

[0021] According to the present invention, even in the presence of hidden terminals, it is possible to appropriately control the transmission timing of each wireless communication terminal in a wireless communication network so as to avoid collisions. Furthermore, by performing phase update processing with the addition of a noise component, it is possible to improve the probability of successful phase synchronization. [Brief explanation of the drawings]

[0022] [Figure 1] 1 is a conceptual diagram illustrating a configuration of a wireless communication system according to an embodiment. [Figure 2] FIG. 4 is a conceptual diagram for explaining the relationship between a reference phase and a plurality of phases in the embodiment. [Figure 3]FIG. 10 is a conceptual diagram for explaining a simulation result of transmission timing control according to the embodiment. [Figure 4] FIG. 10 is a conceptual diagram for explaining a simulation result of transmission timing control according to the embodiment. [Figure 5] FIG. 10 is a conceptual diagram showing a successful example of phase synchronization. [Figure 6] FIG. 10 is a conceptual diagram showing an example of a phase synchronization failure. [Figure 7] 10 is a flowchart summarizing a transmission timing control method in each node according to an embodiment. [Figure 8] FIG. 2 is a block diagram illustrating a configuration example of a node according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0023] An embodiment of the present invention will be described with reference to the accompanying drawings.

[0024] 1. Example of wireless communication system configuration 1 is a conceptual diagram showing a schematic configuration of a wireless communication system 1 according to this embodiment. The wireless communication system 1 includes a plurality of wireless communication terminals 10 and a central wireless communication device 20. The plurality of wireless communication terminals 10 and the central wireless communication device 20 form a wireless communication network 2. The central wireless communication device 20 and each wireless communication terminal 10 can communicate with each other. For example, the wireless communication network 2 is a wireless sensor network, the wireless communication terminals 10 are sensor terminals, and the central wireless communication device 20 is a gateway. As another example, the wireless communication terminals 10 may be wireless LAN terminals, and the central wireless communication device 20 may be an access point.

[0025] In the following description, for the sake of simplicity, the wireless communication terminal 10 will be referred to as a "node 10" and the central wireless communication device 20 will be referred to as a "central node 20".

[0026] The wireless communication network 2 includes N nodes 10-1 to 10-N. N is the total number of nodes 10 and is an integer equal to or greater than 2. In the example shown in FIG. 1, N is 6, but is not limited to this. Each of the N nodes 10-1 to 10-N is represented by a "node 10-i." i is an identifier of each node 10 and takes a value from 1 to N.

[0027] Each node 10-i transmits a packet to the central node 20. In particular, each node 10-i periodically transmits a packet to the central node 20. The transmission timing of each node 10-i is expressed by a "phase" within a predetermined transmission period. In other words, each node 10-i transmits a packet at a transmission timing corresponding to a phase within the predetermined transmission period. At this time, it is desirable to appropriately control the transmission timing of each node 10-i so as to avoid collisions.

[0028] 2. Method described in Non-Patent Document 2 Regarding the scheduling of transmission timing, first, the method described in Non-Patent Document 2 will be described. Each node 10-i has "multiple phases" as transmission timings within a predetermined transmission period. For example, the multiple phases include a "first phase α1" and a "second phase α2." The average value of the first phase α1 and the second phase α2 of each node 10-i will be hereinafter referred to as the "reference phase θ i " is called.

[0029] Figure 2 shows the reference phase θ i , a first phase α1, and a second phase α2. The first phase α1 is a reference phase θ i from the reference phase θ i On the other hand, the second phase α2 is obtained by subtracting the adjustment phase β from the reference phase θ i from the reference phase θ i The reference phase θ is obtained by adding the adjustment phase β to the i is the average value of the first phase α1 and the second phase α2.

[0030] Each node 10-i has its own reference phase θ iThe first phase α1 and the second phase α2 based on the above are set as the packet transmission timing. Each node 10-i sets its own reference phase θ according to the following equations (6) to (10) at its own packet transmission timing. i , the first phase α1, and the second phase α2. Then, each node 10-i notifies other nodes 10-j (j=1 to N, j≠i) of its own updated phase (α1, α2) information through packet transmission. In other words, each node 10-i shares the latest phase information of the multiple nodes 10-1 to 10-N and autonomously updates its own phase (α1, α2).

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[0036] r is an order parameter and is a real number greater than 0 and less than or equal to 1. K is the coupling strength between the nodes 10. ΔT is a unit time (control period). a1 is a real number greater than or equal to 0 and less than or equal to 1.

[0037] The overall average phase φ is the reference phase θ of the entire N nodes 10-1 to 10-N. i As can be seen from equations (7) to (9), the reference phase θ iSince α is the average value of the first phase α1 and the second phase α2, the overall average phase φ can also be said to be the average value of the multiple phases (α1, α2) of all N nodes 10-1 to 10-N. This overall average phase φ can be calculated from the phase information of the N nodes 10-1 to 10-N.

[0038] As described above, the adjusted phase β defines the difference between the reference phase θi and the multiple phases (α1, α2). As can be seen from equations (8) and (9), the adjusted phase β is set to be different among the N nodes 10-1 to 10-N.

[0039] According to the above equation (6), the reference phase θ of each node 10-i i In other words, each node 10-i calculates the overall average phase φ and adjusts the reference phase θ i Furthermore, each node 10-i updates the updated reference phase θ i That is, the first phase α1 and the second phase α2 are calculated based on the reference phase θ i When the reference phase θ of each node 10-i is updated, the first phase α1 and the second phase α2 are also updated accordingly. By repeating such a phase update process, the reference phase θ of each node 10-i is updated. i The phase θ of each node 10-i converges to the overall average phase φ. i will synchronize.

[0040] Reference phase θ i and the multiple phases (α1, α2), an adjusted phase β is set to be different among the N nodes 10-1 to 10-N. Therefore, the transmission timings (α1, α2) of the N nodes 10-1 to 10-N are distributed without overlapping within a predetermined transmission period. In this way, the N nodes 10-1 to 10-N control their own transmission timings (α1, α2) in an autonomous distributed manner to prevent collisions with each other, and perform time-division communication.

[0041] Compared with the conventional equation (5), it can be seen that the overall average phase φ expressed by equation (10) does not include the adjustment phase β specific to each node 10-i. This is because the adjustment phase β of the first phase α1 and the adjustment phase β of the second phase α2 cancel each other out when calculating the overall average phase φ. As a result, even in a situation where a hidden terminal is present, the overall average phase φ after convergence becomes a common value within the wireless communication network 2. In other words, even in a situation where a hidden terminal is present, each node 10-i within the wireless communication network 2 can autonomously and appropriately control its own transmission timing to avoid collisions. This enables efficient time-division communication.

[0042] Each node 10-i receives radio environment information including the total number N of nodes 10 and its own identifier i from the control device. For example, the control device is the central node 20. Furthermore, each node 10-i notifies other nodes 10-j of its own phase information and receives phase information of other nodes 10-j from the other nodes 10-j. Each node 10-i calculates an overall average phase φ based on the phase information of the N nodes 10-1 to 10-N, and calculates a reference phase θ according to equations (6) to (10). i and multiple phases (α1, α2). That is, each node 10-i updates the reference phase θ i The reference phase θi and the multiple phases (α1, α2) are updated so that the phase θi approaches the overall average phase φ and the multiple phases (α1, α2) differ among the N nodes 10-1 to 10-N.

[0043] Each node 10-i transmits a packet using each of a plurality of phases (α1, α2) in a predetermined transmission period as the transmission timing. For example, consider that the phase of each node 10-i is normalized to a range of 0 to 1. The phase changes from 0 to 1 and then returns to 0. When the phase of a certain node 10-i becomes 1, the node 10-i updates its own phase (α1, α2) in accordance with the above equations (6) to (10). The node 10-i also transmits a packet including the updated phase information. As a result, the node 10-i notifies the other node 10-j of the updated phase information. The other node 10-j updates its own phase (α1, α2) in accordance with the above equations (6) to (10). Next, the phase of the other node 10-j becomes 1. By repeating this process, the phase is updated.

[0044] 3 and 4 are conceptual diagrams for explaining the results of a simulation of transmission timing control. Here, six nodes 10-1 to 10-6 are considered. FIG. 3 shows an example of node arrangement. The central node 20 is located at coordinates [0,0], and each node 10 is located at a distance from the central node 20. The unit of distance is m. Nodes 10 that are 1000 m or more apart are considered hidden terminals. Each node 10 transmits a packet to the central node 20. Each node 10 also acquires information on the transmission timing of other surrounding nodes 10 within its receivable range. Each node 10 then updates its own phase (α1, α2) according to the above equations (6) to (10). FIG. 4 is a conceptual diagram showing an example of updating the movement (α1, α2) of each node 10. The horizontal axis represents time, and the vertical axis represents phase (transmission timing). From FIG. 4, it can be seen that the transmission timing of each node 10 is equally spaced apart even in a situation where hidden terminals exist.

[0045] In the above example, the multiple phases of each node 10-i in a given transmission period include a first phase α1 and a second phase α2. However, the number of phases is not limited to this. The number of multiple phases of each node 10-i in a given transmission period may be three or more. The reference phase θ of each node 10-i iis the average value of multiple phases, and the reference phase θ i If the difference between the phases is different between the nodes 10, a similar effect can be achieved.

[0046] 3.Improved probability of successful phase synchronization 3-1.Challenges By repeating the phase update process according to the above equation (6), the reference phase θ i It is expected that the phases will be synchronized. However, this does not necessarily mean that the phase synchronization will be successful. FIG. 5 shows an example of successful phase synchronization, and FIG. 6 shows an example of unsuccessful phase synchronization. In each of FIG. 5 and FIG. 6, the vertical axis represents the reference phase θ of each node 10-i. i The horizontal axis represents time.

[0047] One of the reasons for the failure of phase synchronization is that the phase update process is performed when there is a large difference in the reference phase θ between the nodes 10. i There are two timings for updating the reference phase θ of the other node 10-j: (1) when the node 10-i itself transmits a packet, and (2) when the node 10-i receives the phase information of the other node 10-j from the other node 10-j. j and its own reference phase θ i When the deviation between the reference phase θ i is the reference phase θ of the other node 10-j j The reference phase θ j If the phase difference between the nodes 10-i and 10-i changes significantly, the timing of the node 10-i's packet transmission will also change significantly. As a result, packet collisions may occur, potentially depriving the surrounding nodes 10 of packet transmission opportunities. If packet transmission opportunities are deprived, the latest phase information may not be shared properly, and phase synchronization may fail.

[0048] 3-2.Improvement of phase update process Therefore, this embodiment further proposes a technique that can improve the probability of successful phase synchronization. According to this embodiment, the phase update width in the phase update process is adjusted to be smaller than the phase update width given by the above equation (6). More specifically, a noise component is actively added to the overall average phase φ so that the phase update width is reduced.

[0049] For example, the following equations (11) to (13) are used as phase update equations in the phase update process instead of the above equation (6).

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[0053] φ shown in equation (12) withNoise is the overall average phase to which a noise component is added. The overall average phase φ in the above equation (6) is converted to the overall average phase φ shown in equation (12). withNoise By replacing , we obtain equation (11). random() is a random value greater than 0 and less than 1. That is, the noise component in equation (12) includes a random component. NumofNodes is the number of nodes 10 whose phases are taken into consideration in the calculation of the phase update process. The parameter X is arbitrary, but is set to 10, for example. By adjusting the parameter X, the width of the noise component in equation (12) can be adjusted. For example, when calculations are performed on five nodes 10, the phase interval when synchronization is established is 36 degrees (= (360 degrees / (5 × 2)). The width of the noise component in equation (12) is set to, for example, 1 / 20, 1 / 10, etc. of the phase interval.

[0054] In this way, according to this embodiment, a noise component is actively added so that the phase update width in the phase update process is reduced. Since the phase update width is reduced, the reference phase θ i As a result, the probability of packet collisions occurring is reduced, and the probability that packet transmission opportunities of surrounding nodes 10 are deprived is also reduced. By sharing the latest phase information and repeating the phase update process, the probability of successful phase synchronization without breakdown increases.

[0055] The following equation (14) shows a modified example of the noise component.

[0056]

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[0057] In equation (14), M is the number of phase update processes (number of calculations). As the number of phase update processes M increases, the noise component (i.e., the amount of decrease in the phase update width) decreases. In other words, the phase update width decreases significantly at first, and then gradually increases as the number of phase update processes M increases. This also achieves the same effect.

[0058] 3-3.Processing flow FIG. 7 is a flowchart summarizing the transmission timing control method in each node 10-i.

[0059] Each node 10-i, which uses each of a plurality of phases as a transmission timing within a predetermined transmission period, updates its own phase at the packet transmission timing in accordance with the above equations (7) to (14) (step S101). At this time, each node 10-i calculates the overall average phase φ based on the phase information of each of the nodes 10-1 to 10-N. Furthermore, each node 10-i calculates the overall average phase φ by adding a noise component to the overall average phase φ so that the phase update width decreases. withNoise Then, each node 10-i obtains a reference phase θ i is the overall average phase φ withNoiseand the phases are different among the nodes 10-1 to 10-N (phase update process). Furthermore, each node 10-i notifies the other nodes 10-j of the updated phase information by transmitting a packet (step S102).

[0060] Each node 10-i receives phase information from other nodes 10-j within its receivable range (step S103). In response to receiving the phase information from other nodes 10-j, each node 10-i updates its own phase according to the above equations (7) to (14) (step S104). At this time, each node 10-i calculates the overall average phase φ based on the phase information of each of the nodes 10-1 to 10-N. Furthermore, each node 10-i calculates the overall average phase φ by adding a noise component to the overall average phase φ so that the phase update width decreases. withNoise Then, each node 10-i obtains a reference phase θ i is the overall average phase φ withNoise and the phases of the nodes 10-1 to 10-N are different from each other (phase update process).

[0061] Effects According to this embodiment, even in a situation where a hidden terminal exists, each node 10-i in the wireless communication network 2 can autonomously and appropriately control its own transmission timing to avoid collisions, thereby enabling efficient time-division communication.

[0062] Furthermore, according to this embodiment, a noise component is actively added so that the phase update width in the phase update process is reduced. Since the phase update width is reduced, the reference phase θ i As a result, the probability of packet collisions occurring is reduced, and the probability that packet transmission opportunities of surrounding nodes 10 are deprived is also reduced. By sharing the latest phase information and repeating the phase update process, the probability of successful phase synchronization without breakdown increases.

[0063] 4. Node configuration example 8 is a block diagram showing an example configuration of the node 10 according to this embodiment. The node 10 includes a communication controller 100 and a radio unit 110. The communication controller 100 controls radio communication. The radio unit 110 includes an antenna and a transmission / reception circuit.

[0064] The communication controller 100 is a computer including one or more processors 101 (hereinafter simply referred to as "processors 101") and one or more storage devices 102 (hereinafter simply referred to as "storage devices 102"). The processor 101 performs various types of information processing. For example, the processor 101 includes a CPU (Central Processing Unit). The storage devices 102 store various types of information required for processing by the processor 101. Examples of the storage devices 102 include volatile memory, non-volatile memory, HDD (Hard Disk Drive), SSD (Solid State Drive), etc.

[0065] The control program 103 is a computer program executed by the processor 101. The functions of the communication controller 100 are realized by cooperation between the processor 101 executing the control program 103 and the storage device 102. The control program 103 is stored in the storage device 102. The control program 103 may be recorded on a computer-readable recording medium. The control program 103 may be provided to the communication controller 100 via a network.

[0066] The radio environment information 104 indicates the environment of the wireless communication network 2. For example, the radio environment information 104 includes the total number N of nodes 10 and their own identifiers i. The communication controller 100 receives the radio environment information 104 from, for example, the central node 20. The radio environment information 104 is stored in the storage device 102.

[0067] The communication controller 100 executes the transmission timing control (see FIG. 7) according to this embodiment based on the radio environment information 104 and the above equations (7) to (14). Then, the communication controller 100 transmits the packet via the radio unit 110. [Explanation of symbols]

[0068] 1. Wireless communication systems 2. Wireless communication networks 10 Wireless communication terminal (node) 20 Central radio communication equipment 100 Communication Controller 101 processors 102 Storage device 103 Control Program 104 Wireless environment information 110 Radio Department

Claims

1. A wireless communication terminal in a wireless communication network including a plurality of wireless communication terminals, A communication controller is provided, The communication controller A process of setting each of a plurality of phases in a predetermined period as a packet transmission timing; A process of calculating an overall average phase which is an average value of the plurality of phases across the plurality of wireless communication terminals; a phase updating process of adding a noise component to the overall average phase and updating the plurality of phases of the wireless communication terminal so that an average value of the plurality of phases of the wireless communication terminal approaches the overall average phase to which the noise component has been added and the plurality of phases differ among the plurality of wireless communication terminals; a process of notifying other wireless communication terminals of the updated phase information through packet transmission; configured to run Wireless communication terminal.

2. 2. The wireless communication terminal according to claim 1, The noise component includes a random component. Wireless communication terminal.

3. 2. The wireless communication terminal according to claim 1, The noise component is set to decrease as the number of times the phase update process is performed increases. Wireless communication terminal.

4. 2. The wireless communication terminal according to claim 1, the average value of the plurality of phases is a reference phase; The plurality of phases are: a first phase obtained by subtracting an adjustment phase from the reference phase; a second phase obtained by adding the adjustment phase to the reference phase; Including, the adjustment phases are set to be different among the plurality of wireless communication terminals; The phase update process includes: updating the reference phase so that it approaches the overall average phase to which the noise component has been added; calculating the plurality of phases of the wireless communication terminal based on the updated reference phase; Contains Wireless communication terminal.

5. 5. The wireless communication terminal according to claim 4, The phases are updated according to the following formula: [Equation 1] [Equation 2] [Equation 3] [Equation 4] [Equation 5] [Equation 6] where: N is the total number of the plurality of wireless communication terminals, i is an identifier of each of the plurality of wireless communication terminals and takes a value from 1 to N, θ ｉ is the reference phase of each of the plurality of wireless communication terminals, r is the order parameter, a real number greater than 0 and less than or equal to 1; K is the coupling strength between the plurality of wireless communication terminals, ΔT is unit time, φ is the ensemble mean phase, β is the adjustment phase, a １ is a real number between 0 and 1, α1 is the first phase, α2 is the second phase, φ ｗｉｔｈＮｏｉｓｅ is the overall average phase to which the noise component is added, random() is a random value greater than 0 and less than 1, NumovNodes is the number of wireless communication terminals whose phases are taken into consideration in the phase update process, X is an arbitrary parameter Wireless communication terminal.

6. A transmission timing control method in each of a plurality of wireless communication terminals in a wireless communication network, comprising: a process in which each of the wireless communication terminals sets a plurality of phases in a predetermined period as packet transmission timings; A process of calculating an overall average phase which is an average value of the plurality of phases across the plurality of wireless communication terminals; a phase updating process of adding a noise component to the overall average phase and updating the plurality of phases of each of the wireless communication terminals so that an average value of the plurality of phases of each of the wireless communication terminals approaches the overall average phase to which the noise component has been added and the plurality of phases differ among the plurality of wireless communication terminals; a process of notifying other wireless communication terminals of the updated phase information through packet transmission; Contains Transmission timing control method.

7. 7. A transmission timing control method according to claim 6, The noise component includes a random component. Transmission timing control method.

8. 7. A transmission timing control method according to claim 6, The noise component is set to decrease as the number of times the phase update process is performed increases. Transmission timing control method.

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