JP4277852B2 - Communication timing control device, communication timing control method, node, and communication system - Google Patents

Description

  The present invention relates to a communication timing control apparatus, a communication timing control method, a node, and a communication system, and more particularly to an apparatus and method for controlling data transmission timing of each node in a communication system including a plurality of nodes.

  For example, as a method for determining the data transmission timing of each node in a wireless communication network such as a sensor network or a wireless LAN (Local Area Network), for example, CSMA / CA (Carrier) in which each node autonomously determines the transmission timing. Sense Multiple Access With Collision Avoidance) (see Non-Patent Document 1).

  However, in CSMA / CA, as traffic increases, overhead increases and communication efficiency decreases. Therefore, a technique for improving communication efficiency using a simplified collision avoidance function in access control as disclosed in Patent Document 1 has been proposed.

  Patent Document 1 discloses a communication timing control technique in which a plurality of nodes constituting a network autonomously determine a time slot for data transmission.

  Each node transmits a communication timing signal (impulse signal) almost periodically and also receives a communication timing signal from surrounding nodes and adjusts the transmission timing of its own node. In the network, a node that intends to transmit a data signal can transmit a data signal until it transmits a communication timing signal from its own node and immediately before another node transmits the communication timing signal.

  Note that after starting communication timing control, data transmission can be started if a time slot necessary for transmitting data is allocated to the own node.

Matsushita Atsushi, Nakagawa Masao, “Wireless LAN Architecture”, Kyoritsu Shuppan, 1996, p. 47, 53-59, 69 JP 2005-94663 A

  By the way, when the communication timing control technique disclosed in Patent Document 1 is adopted, each node transmits a data signal from the start of communication timing until a time slot necessary for transmitting data is allocated to the node. Has stopped.

  Therefore, it is possible to shorten the time until the time slot for data transmission is secured at startup (this is called the convergence time), to set a longer time available for data transmission, and to further improve the efficiency of data transfer There is a need for a communication timing control device, a communication timing control method, a node, and a communication system.

In order to solve this problem, the communication timing control devices according to the first to third aspects of the present invention are (1) received from other nodes in the communication timing control device mounted in each of a plurality of nodes constituting the communication system. The transmission timing of the timing signal transmitted by the own node is determined using the reception timing of the timing signal, and the transmission time slot of the data signal is determined based on the transmission timing and the reception timing of the timing signal from another node. Communication timing control means for performing communication timing control, and (2) execution timing for starting communication timing control of the communication timing control means when joining the network is dynamically determined based on a predetermined rule assigned in advance to each node. Start at the execution timing based on the startup order determined by And (2-1) communication timing control processing by the communication timing control means and / or data signal transmission / reception processing based on predetermined information used in the communication timing control means. (2) an execution timing setting for setting the execution timing of the communication timing control to be executed by the communication timing control means based on the determined activation order; Part. In the communication timing control apparatus according to the first aspect of the present invention, the activation order determination unit determines the activation order based on the number of other nodes that is sharing the transmission time slot with the own node. The communication timing control apparatus according to the second aspect of the present invention is characterized in that the activation order determination unit determines the activation order based on data amount information of a transmission data signal transmitted by the node. Third communication timing control apparatus of the present invention, the activation order determination unit is characterized that you determine the starting order based on the routing information of the transfer data signal passing through the self node.

The communication timing control methods of the fourth to sixth aspects of the present invention are the communication timing control method of the communication timing control device mounted on each of the plurality of nodes constituting the communication system, wherein (1) the communication timing control means is connected from another node. Based on the reception timing of the received timing signal, the transmission timing of the timing signal transmitted by the own node is determined. Based on the transmission timing and the reception timing of the timing signal from another node, the transmission time slot of the data signal is determined. A communication timing control step for performing communication timing control to be determined; and (2) an execution timing at which the control means starts communication timing control of the communication timing control means when joining the network is determined in advance for each node. Dynamically determined launch based on rules It possesses a startup control process to start execution timing position in based, activation control means, based on predetermined information used in the process of transmitting and receiving (2-1) a communication timing control processing by the communication timing control means and or data signals Then, an activation order determination step for determining an activation order for the node to execute communication timing control, and (2-2) execution of communication timing control to be performed by the communication timing control means based on the determined activation order. An execution timing setting step for setting timing. The communication timing control method according to the fourth aspect of the present invention is characterized in that, in the activation order determination step, the activation order is determined based on the information on the number of other nodes competing with the own node and the transmission time slot. The communication timing control method of the fifth aspect of the present invention is characterized in that, in the activation order determination step, the activation order is determined based on data amount information of a transmission data signal transmitted by the node. Communication timing control method of the present invention the sixth, the start order determining step, characterized that you determine the start order based on the routing information of the transfer data signal passing through the self node.

A node according to a seventh aspect of the present invention includes the communication timing control device according to any one of the first to third aspects of the present invention.

A communication system according to an eighth aspect of the present invention includes a plurality of nodes according to the seventh aspect of the present invention.

  According to the communication timing control device, the communication timing control method, the node, and the communication system of the present invention, it is possible to reduce the time required to secure a data transmission time slot at the time of activation, and to increase the time available for data transmission. It can be set, and the efficiency of data transfer can be further improved.

(A) First Embodiment Hereinafter, embodiments of a communication timing control device, a communication timing control method, a node, and a communication system according to the present invention will be described with reference to the drawings.

(A-1) Configuration of First Embodiment (A-1-1) Communication Timing Control Device FIG. 2 shows an arrangement example of a plurality of nodes constituting the communication system (network) according to the present embodiment. FIG. 2 shows a communication system including nine nodes 1 to 9, and the internal configuration of each of the nodes 1 to 9 is the same.

  In FIG. 2, arrows indicate that data signals can be directly transmitted and received between nodes. That is, for example, the node 1 is in a position where data signals can be transmitted and received between the three nodes 2 and 4 including its own node. Similarly, node 2 is in a position where data signals can be transmitted and received between four nodes, and node 5 is capable of transmitting and receiving data signals between five nodes.

  Further, it is assumed that transmission / reception of a communication timing signal (impulse signal) by each node is also performed with a node having a distance range twice the arrival distance of the data signal. For example, the node 1 keeps the communication timing among the six nodes, including nodes 2, 3, 4, 5, and 7, including its own node. Similarly, it is assumed that the node 2 has communication timings among the seven nodes of the nodes 1, 3, 4, 5, 6, and 8 and the node 5 has a communication timing among all nine nodes.

  FIG. 1 is a functional block diagram showing an internal configuration of a communication timing control device 10A installed in each of the nodes 1-9.

  As shown in FIG. 1, the communication timing control device 10A of the present embodiment includes a communication timing signal receiving means 11, a communication timing calculating means 12, a communication timing signal transmitting means 13, a neighboring node number measuring means 14, and an activation time setting means 15. And at least data communication means 16.

  The communication timing signal receiving unit 11 receives a communication timing signal (impulse signal) transmitted by a nearby node N (for example, another node existing in a range where a transmission radio wave of the node reaches).

  Here, the communication timing signal (impulse signal) is exchanged with a nearby node as a timing signal related to data transmission, and has an impulse shape such as a Gaussian distribution shape.

  In this embodiment, the communication timing signal receiving unit 11 gives the received impulse signal itself, a waveform of the impulse signal, or an impulse signal regenerated based on the received impulse signal to the communication timing calculating unit 12. .

  Based on the communication timing signal (impulse signal) given from the communication timing signal receiving unit 11, the communication timing calculating unit 12 forms a phase signal that defines the communication timing of the own node, and transmits the communication timing signal of the own node. The timing and data transmission timing are determined. Details of a configuration example of the communication timing calculation unit 12 will be described later.

  The communication timing signal transmission unit 13 transmits a communication timing signal (impulse signal) to the network at the timing determined by the communication timing calculation unit 12.

  The data communication unit 16 transmits a data signal at the data communication timing determined by the communication timing calculation unit 12. The data communication means 16 receives a data signal that has arrived from the network.

  The neighboring node number measuring unit 14 measures the number of nodes with which the communication timing calculating unit 12 directly communicates with the communication timing, and holds the measured number of nodes as the number of neighboring nodes. The neighboring node number measuring unit 14 gives the number of neighboring nodes held to the activation time setting unit 15.

  Here, a method of holding the number of neighboring nodes in the neighboring node number measuring unit 14 will be described.

  For example, the neighboring node number measuring unit 14 detects a receiving node based on a transmission source address given to a received communication timing signal (impulse signal), and creates a receiving node list 14a. At this time, the receiving node list 14a is created based on the source address so that there is no duplicate registration in the receiving node list 14a. Then, the neighboring node number measuring unit 14 measures the number of nodes listed in the receiving node list 14a as the number of neighboring nodes.

  The neighboring node number measuring means 14 measures the communication timing signal received within a predetermined time because the neighboring node number may vary with time.

  If the communication timing calculation means has a similar function, it is not necessary to install the neighboring node number measurement means 14.

  The activation time setting means 15 monitors the operation of the communication timing calculation means 12, and determines the activation time for starting the communication timing control of the communication timing calculation means 12 to be restarted.

  Thereby, based on the communication timing control by the communication timing calculation means 12, the starting time of the communication timing control at the next restart can be set.

  In addition, when the communication timing control of the communication timing calculation unit 12 is restarted (for example, when a start request is received from the communication timing calculation unit 12), the start time setting unit 15 calculates a start signal according to the set start time. It is given to the means 12 and restarted.

  In the present embodiment, the activation time setting unit 15 refers to the activation standby time setting table 15a, determines a predetermined priority based on the number of neighboring nodes measured by the neighboring node number measuring unit 14, and according to the priority. By providing the standby time, the time for starting the communication timing control of the communication timing calculation means 12 is determined.

  For example, the activation time setting unit 15 sets the standby time to be reduced and the communication timing control to be activated earlier as the number of neighboring nodes increases. The difference in the communication timing start depending on the priority is, for example, that the start is delayed by a time corresponding to one frame period each time one priority is lowered.

(A-1-2) Detailed Description of Configuration of Communication Timing Calculation Unit The communication timing signal receiving unit 11 is a communication transmitted by a nearby node N (for example, another node existing in a range where a transmission wave of the node reaches). A timing signal (impulse signal) is received.

  Here, the communication timing signal (impulse signal) is exchanged with a nearby node as a timing signal related to data transmission, and has an impulse shape such as a Gaussian distribution shape.

  In this embodiment, the communication timing signal receiving unit 11 gives the received impulse signal itself, a waveform of the impulse signal, or an impulse signal regenerated based on the received impulse signal to the communication timing calculating unit 12. .

  Based on the communication timing signal (impulse signal) given from the communication timing signal receiving unit 11, the communication timing calculating unit 12 forms a phase signal that defines the communication timing of the own node, and transmits the communication timing signal of the own node. The timing and data transmission timing are determined.

Here, assuming that the node i is the node i and the phase value of the phase signal at time t is θi (t), the communication timing calculation unit 12 changes the phase signal θi () in increments as shown in the equation (1). t) is changed. The expression (1) is an expression modeling nonlinear vibration, but an expression modeling other nonlinear vibration can also be applied. The phase signal θi (t) can also be regarded as a state variable signal of the own node.

  Expression (1) is an expression representing a rule for changing the rhythm of nonlinear vibration of the phase signal θi (t) of the own node i based on the signal given from the communication timing signal receiving means 11. In the equation (1), the first term ω (natural angular frequency parameter) on the right side represents a basic change rhythm (corresponding to “basic speed for transitioning its own operation state”) included in each node, The second term on the right side represents the nonlinear change. Here, the value of ω is, for example, the same value throughout the system. The function Pk (t) represents an impulse signal received from the neighboring node k (k is assumed to be 1 to N).

  The function R (θi (t), σ (t)) is a function that expresses a response characteristic that changes its basic rhythm in response to reception of an impulse signal from another node. Yes. Equation (2) is an equation for determining the phase response function with a sine wave having a phase value in which random noise is superimposed on the opposite phase of the phase signal θi (t) at time t.

  A non-linear characteristic in which neighboring nodes N are in opposite phases (vibration phase is inverted phase) is realized, and collision avoidance is executed using the characteristic. That is, an appropriate time relationship (time difference) is formed at the timing when the value of the phase signal of each node becomes the same value so that the transmission timing of the impulse signal between neighboring nodes N does not collide.

  In the equation (2), the constant term π [rad] representing the function σ (t) functions as a non-linear characteristic that the neighboring nodes N try to be in opposite phases, and the random noise function φ (t) is It functions to give random variability to the nonlinear characteristic (the function φ (t) follows, for example, a Gaussian distribution with an average value of 0). Here, the reason why random variability is given to the non-linear characteristic is that the system does not reach the target stable state (optimal solution), but copes with the decrease that falls into another stable state (local solution). Because.

  In the equation (2), the form using the sin function is shown as the simplest example of the phase response function R (θi (t), σ (t)), but other functions are used as the phase response function. It may be. Further, instead of the constant term π of the function σ (t), a constant λ other than π (0 <λ <2π) may be used. In this case, the neighboring nodes are not in antiphase but in different phases. To function.

  The meaning of the above-described function of the communication timing calculation means 12 will be described in detail with reference to FIGS. Note that the state changes shown in FIGS. 3 and 4 are also related to the function of the communication timing signal transmission means 13.

  3 and 4 show a relationship formed between a target node (own node) and a neighboring node (another node) when attention is paid to a certain node, that is, a phase relationship between respective nonlinear vibration rhythms. Shows how the changes over time.

  FIG. 3 shows a case where there is one neighboring node j for the node of interest i. In FIG. 3, the motion of the two mass points rotating on the circle represents the nonlinear vibration rhythm corresponding to the node of interest and the neighboring nodes, and the angle of the mass point on the circle represents the value of the phase signal at that time. Yes. The motion of the point where the rotational motion of the mass point is projected on the vertical or horizontal axis corresponds to the nonlinear vibration rhythm. By the operation based on the formulas (1) and (2), the two mass points tend to be in opposite phases to each other. Even if the two mass points are close to each other in the initial state as shown in FIG. As time passes, the state (transient state) shown in FIG. 3B is changed to a steady state in which the phase difference between the two mass points is almost π as shown in FIG. 3C.

  Each of the two mass points rotates with the natural angular frequency parameter ω as a basic angular velocity (corresponding to a basic velocity that changes its own operation state). Here, when an interaction based on transmission / reception of an impulse signal occurs between nodes, these mass points change (slow / slow) angular velocities, respectively, and eventually reach a steady state in which an appropriate phase relationship is maintained. This operation can be regarded as forming a stable phase relationship by repelling each other while the two mass points rotate. In the steady state, as will be described later, when the output impulse signal is transmitted when each node is in a predetermined phase (for example, 0), the transmission timings at the mutual nodes form an appropriate time relationship. become.

  FIG. 4 shows a case where there are two neighboring nodes j1 and j2 for the node of interest i. Even in the case where there are two neighboring nodes, a stable phase relationship (stability related to temporal relationship) is formed by repelling each other while rotating the respective mass points as described above. The same applies to the case where the number of neighboring nodes is 3 or more.

  The formation of the above-described stable phase relationship (steady state) has a very adaptive (flexible) property with respect to changes in the number of neighboring nodes. For example, it is assumed that one neighboring node is added when there is one neighboring node with respect to the node of interest and a stable phase relationship (steady state) is formed. The steady state once collapses, but after passing through the transient state, a new steady state in the case where there are two neighboring nodes is reformed. In addition, when a neighboring node is deleted or does not function due to a failure or the like, an adaptive operation is performed in the same manner.

  The communication timing calculation means 12 determines the transmission timing of the Kiju fortune impulse signal based on the obtained phase signal θi (t), and instructs the communication timing signal transmission means 13. That is, when the phase signal θi (t) reaches a predetermined phase α (0 ≦ α <2π), the transmission of the reference impulse signal is instructed. Here, it is preferable that the predetermined phase α is previously unified in the entire system. In the following description, it is assumed that α = 0 is unified throughout the system. In the example of FIG. 3, since the phase signals of the node i and the node j are shifted by π in a steady state, the output impulse signal from the node i is not limited even if α = 0 is unified throughout the system. Is different from the transmission timing of the output impulse signal from the node j by π.

  Further, the communication timing calculation means 12 performs the “transient state” (FIG. 3B, FIG. 4B) when the mutual adjustment of the transmission timing of the reference impulse signal performed between the own node and one or a plurality of neighboring nodes. Reference) or “steady state” (see FIG. 3C and FIG. 4C). The communication timing calculation means 12 observes the reception timing of the impulse signal (reference impulse signal and response impulse signal) and the transmission timing of the reference impulse signal from its own node, and between the transmission timings of a plurality of nodes that exchange the impulse signal. When the time difference is stable in time, it is determined that the state is “steady state”. In this embodiment, the communication timing calculation unit 12 uses the phase signal θi (t) as a signal for capturing the transmission timing of the impulse signal from the own node.

  For example, the communication timing calculation unit 12 executes the following processes (a) to (d) to perform the tuning determination.

  (A) The value β of the phase signal θi (t) at the output timing of the signal from the impulse signal receiving means 11 is observed over one period of the phase signal θi (t). Here, as a result of the above observation, the obtained phase signal values β are β1, β2,..., ΒN (0 <β1 <β2 <... ΒN <2π).

  (B) Based on the observed value β of the phase signal θi (t), the difference between adjacent values (phase difference) Δ1 = β1, Δ2 = β2-β1,..., ΔN = βN−β (N -1) is calculated.

  (C) The processes of (a) and (b) are performed in units of the period of the phase signal θi (t), and the amount of change (difference) in the phase difference Δ in successive periods γ1 = Δ1 (τ + 1) − Δ1 (τ), γ2 = Δ2 (τ + 1) −Δ2 (τ),..., ΓN = ΔN (τ + 1) −ΔN (τ) are calculated. Here, τ indicates a certain cycle of the phase signal θi (t), and τ + 1 indicates the next cycle of the phase signal θi (t).

  (D) When the above-mentioned change amount γ is smaller than the minute parameter (threshold value) ε, that is, when γ1 <ε, γ2 <ε,. To do.

  Note that a steady state may be determined when the conditions of γ1 <ε, γ2 <ε,..., ΓN <ε are satisfied over M cycles. As the value of M is increased, it is possible to determine “steady state” in a more stable state. Further, the “steady state” may be determined based on a part of the received impulse signals.

  When the tuning determination result indicates “steady state”, the communication timing calculation unit 12 has a minimum value β1 of the value β of the phase signal θi (t) at the reception timing of the impulse signal for each period of the phase signal θi (t). Based on the above, the transmission time (time slot) from the node N is determined, and the data communication signal 16 is instructed.

  The time slot is, for example, a period in which the phase signal θi (t) satisfies δ1 ≦ θi (t) ≦ β1-δ2. The start point of the time slot (the value of the phase signal at that time is δ1) is the timing at which the transmission of the reference impulse signal is finished, and the end point of the time slot (the value of the phase signal at that time is β1-δ2). Is set to a timing slightly offset δ2 before the timing of the first received impulse signal for each period of the phase signal. δ1 and δ2 are an impulse signal (including both the case where the transmission source is the own node and the case of the other node) and the data signal (when the transmission source is the own node, the other node) in the wireless space near the node 10 Phase width corresponding to a very short time to compensate for the absence of both at the same time.

(A-2) Operation of the First Embodiment Next, the operation of the communication timing control apparatus 10A of the present invention will be described with reference to the drawings.

  Hereinafter, first, the measurement processing of the number of neighboring nodes in the communication timing control apparatus 10A will be described with reference to FIGS. FIG. 5 is a flowchart showing the process of measuring the number of neighboring nodes.

  First, when a communication timing signal (impulse signal) arrives from another node, the communication timing signal is received by the communication timing signal receiving means 11 (F101) and given to the communication timing calculating means 12.

  When the communication timing signal is supplied to the communication timing calculation unit 12, the communication timing calculation unit 12 performs a predetermined communication timing control process.

  Further, the neighboring node number measuring means 14 extracts the transmission source address given to the received communication timing signal (F102), and determines whether or not the transmission source address exists in the reception node list 14a. (F103). As a result, the number of nodes in direct communication timing control with the own node can be measured.

  Here, FIG. 6 shows a configuration example of the receiving node list 14a. As shown in FIG. 6, the reception node list 14 a is configured to include “node source address” and “last reception time”, and the neighboring node number measurement unit 14 determines the received communication timing signal. The receiving node can be confirmed by referring to the receiving node list 14a based on the transmission source address.

  When the transmission source address of the received communication timing signal exists in the reception node list 14a, the last reception time of the transmission source address registered in the reception node list 14a is updated to the reception time of the communication timing signal. (F104).

  If the transmission source address of the received communication timing signal does not exist in the reception node list 14a, the transmission source address is added to the reception node list 14a (F105) and the reception time of the communication timing signal is finally received. The time is recorded (F106).

  In addition, the last reception time of each node registered in the reception node list 14a is confirmed by the neighboring node number measuring unit 14, and a node that has not been updated for a predetermined time or more is registered in the reception node list 14a. It is determined whether or not (F107).

  If a node whose last reception time has not been updated for a predetermined time or more is registered in the reception node list 14a, it is determined that the node has stopped communication timing control with its own node, The transmission source address and the last reception time of the node are deleted from the reception node list 14a (F108).

  On the other hand, when the recording / updating of the last reception time is less than the predetermined time, the process returns to F101 and the process is repeated.

  As described above, it is possible to measure and hold the number of nodes in which the own node is in communication timing control.

  Next, the setting process of the starting time by the starting time setting means 15 is demonstrated with reference to the flowchart of FIG.

  First, when there is no data to be transmitted and communication timing control is no longer performed in the communication timing calculation means 12, the activation time setting means 15 detects this, and then performs a startup time setting process for starting communication timing control. It is.

  At this time, the activation time setting unit 15 obtains the number of neighboring nodes from the reception node list 14a of the neighboring node number measuring unit 14 (F201), and refers to the activation waiting time setting table 15a to give priority corresponding to the number of neighboring nodes. The degree is determined (F202).

  Further, the activation time setting means 15 refers to the activation standby time setting table 15a, sets the activation standby time according to the priority, sets the activation time for starting the communication timing control, and holds it (F203). .

  Here, FIG. 8 shows a configuration example of the activation standby time setting table 15a. As shown in FIG. 8, the activation waiting time setting table 15a is configured by associating “number of neighboring nodes”, “priority”, and “waiting time” with each other. "Is set according to the number of nodes that are in control of communication timing control including its own node.

  In FIG. 8, in this embodiment, when “the number of neighboring nodes: 9 or more”, “priority: 1”, “waiting time: 0”, and “the number of neighboring nodes: 7-8” “Priority: 2”, “standby time: 1 frame cycle”, and “neighboring node number: 6 or less”, “priority: 3”, “standby time: 2 frame cycle”. The frame period corresponds to the period of the phase signal θi (t) that defines the communication timing in the communication timing calculation unit 12.

  For example, in FIG. 2, it is assumed that all the nodes 1 to 9 are performing data transmission.

  Then, for example, in node 1, since the number of neighboring nodes that are in control of communication timing control is 6 nodes including its own node 1, "priority: 3" and "standby time: 2 frame period" are maintained. Keep it.

  Further, for example, in the node 2, since the number of neighboring nodes that are in control of the communication timing control is 7 nodes including the own node 2, "priority: 2" and "standby time: 1 frame period" are set. For example, in node 5, since the number of neighboring nodes in communication timing control is 9 nodes including its own node 5, "priority: 1" and "standby time: 0 cycle" are held. Keep it.

  When the communication timing calculation means 12 gives a start request to the activation time setting means 15 when trying to activate the communication timing control, the activation time setting means 15 calculates the communication timing after the waiting time that is held. An activation signal is given to the means 12. As a result, the communication timing calculation means 12 that has received the activation signal starts communication timing control.

  Thus, after each node 1-9 waits for the waiting time corresponding to the priority determined by the activation time setting means 15 or more, the transmission of the communication timing control signal is started as shown below. A coordinated data transmission time slot can be formed between the nodes 1 to 9, and the data communication efficiency can be improved.

  FIG. 9 is an image diagram showing an active node that is directly affected by the addition of a node as in the present embodiment.

  As described above, since the node 5 has the “standby time: 0”, the node 5 starts transmitting the communication timing signal immediately after the communication control is started.

  Next, since each of the nodes 2, 4, 6 and 8 has “standby time: 1 frame period”, transmission of a communication timing signal is started after a lapse of one frame period from the start of the first communication control.

  At this time, the nodes 2, 4, 6 and 8 do not start transmission after the lapse of one frame period, but transmit the communication timing between the start of the second stage and the third stage. By doing in this way, the collision of the data signal by the node 2, 4, 6, and 8 starting transmission simultaneously can be avoided.

  Here, the start state of the communication timing control between the nodes 1 to 9 after the elapse of one frame period from the first communication control start stage is referred to as a second stage, and this state is shown in FIG.

  In the second stage of FIG. 9A, communication timing control can be held between the node 5 that started communication control first and the nodes 2, 4, 6, and 8 that started communication control next. In this case, it is assumed that time slots as shown in FIG. 10 are allocated.

  Thereafter, since the nodes 1, 3, 7, and 9 are “standby time: 2 frame periods”, transmission of a communication timing signal is started after a lapse of 2 frame periods from the start of the first communication control. The start state of the communication timing control between the nodes 1 to 9 after the elapse of the two-frame period from the start of the first communication control is referred to as a third stage, and this state is shown in FIG.

  In the third stage of FIG. 9B, the nodes 1, 3, 7 and 9 have a small number of neighboring nodes, so there is a high possibility that a time slot for data transmission can be secured immediately after the transmission is started.

  For example, in the time slot configuration example shown in FIG. 10, node 1 does not coordinate communication timing with node 6 or node 8, so it appears as an empty time slot, and communication is performed at the time slot position of node 6 or node 8 in FIG. If transmission of the timing signal is started, transmission of the communication timing signal can be started without changing the communication timing with the nodes 4 and 5 which are neighboring nodes.

  The other nodes 3, 7, and 9 also do not affect the adjustment of the communication timing of the already activated node by performing the communication timing at a position where it can be seen from the own node and the empty time slot.

  Here, an example in which transmission of communication timing is started in order from a node having a small number of neighboring nodes will be compared with the case of the present embodiment.

  If the communication timing is started from a node having a small number of neighboring nodes, the result is as shown in FIG.

  In the second stage of FIG. 11A, the communication timing between the nodes 1, 3, 7, and 9 that started communication control first and the nodes 2, 4, 6, and 8 that started communication control next. Assume that control is taken and time slots as shown in FIG. 12 are assigned.

  In FIG. 12, the horizontal axis is the time axis, and the vertical axis indicates the overlap of time slots. For example, the communication timing positions of the node 1 and the node 8 are the same.

  After that, when the node 5 starts communication control in the third stage of FIG. 11B, the time slots of the nodes 2, 4, 6 and 8 are determined as shown in FIG. Even if 5 time slots are to be allocated, the time slot overlaps with any of the time slots of nodes 2, 4, 6 and 8, so that it is necessary to adjust the communication timing and to temporarily stop data transmission again.

  Thus, as the number of neighboring nodes increases, there is a higher possibility that the time slot width necessary for data transmission cannot be secured immediately no matter which timing the transmission of the communication timing signal is started.

  Therefore, by starting communication control from a node having a large number of neighboring nodes as in the present embodiment, it is not necessary to adjust communication timing, and communication efficiency can be improved.

(A-3) Effect of First Embodiment As described above, according to this embodiment, the number of nodes that directly communicate with each other is measured for each node, and the startup start time is delayed as the number of nodes decreases. By doing so, when the communication timing is adjusted, the nodes that do not directly affect the surrounding nodes wait for the start, and have already started by starting the communication timing of the own node after seeing the communication timing of the neighboring nodes It becomes unnecessary to change the timing of the node.

  As described above, since the influence of the timing adjustment due to the addition of the node to the network is reduced, the convergence time can be shortened and the data transmission can be efficiently performed.

(B) Second Embodiment Next, a communication timing control device, a communication timing control method, a node, and a communication system according to a second embodiment of the present invention will be described with reference to the drawings.

  The present embodiment is characterized in that the communication timing control device of each node sets the standby time according to the difference in the time slot width allocated to the node and starts communication timing control.

  Therefore, as in the first embodiment, the present invention can be applied to the case where the communication timing calculation unit 12 of each node allocates an equal time slot, but the time slot width to be allocated differs from node to node (that is, the time slot width is not suitable). (Equal) application to the system is particularly effective.

(B-1) Configuration of Second Embodiment FIG. 13 is a functional block diagram showing an internal configuration of a communication timing control device 10B mounted on each node 1 to 9 of the second embodiment. Note that the node arrangement configuration of this embodiment corresponds to the configuration described in FIG.

  As shown in FIG. 13, the communication timing control device 10B of the second embodiment includes a communication timing signal receiving unit 11, a communication timing calculating unit 12, a communication timing signal transmitting unit 13, a time slot width holding unit 21, and a startup time setting. Means 15 and data communication means 16 are included.

  The point that the time slot width holding means 21 is provided instead of the neighboring node number measuring means 14 in the configuration of the first embodiment, and the function of the activation time setting means 14 by using the time slot width holding means 21 are the present embodiment. Is different from the first embodiment. Therefore, differences from the first embodiment will be described in detail below.

  The time slot width holding unit 21 measures the time slot width of data transmission assigned to the own node, which is obtained by the communication timing calculation unit 12, and holds the time slot width.

  Here, as the information held by the time slot width holding unit 21, various information can be applied as long as the time slot width assigned to the own node can be specified.

  For example, the time slot width holding means 21 may be the time width itself related to the time slot of the own node, or when the reference time slot width predetermined for measuring the time slot width is set to “1”. Alternatively, the time slot width of the own node relative to the reference time slot width may be used. Further, the time slot width holding means 21 may be the ratio of the time slot of the own node in the phase period of the phase signal of the communication timing calculation means 12.

  Similarly to the first embodiment, the activation time setting means 15 sets a standby time for the next activation during the communication timing control, and waits after the start request is given from the communication timing calculation means 12. Later, an activation signal is given to the communication timing calculation means 12 to start communication timing control.

  The activation time setting means 15 determines the priority according to the time slot width assigned to the own node held by the time slot width holding means 21 and sets the standby time based on the priority. , Set the startup time.

  Here, the activation time setting means 15 has, for example, an activation standby time setting table 15b, and determines the priority and the standby time with reference to the activation time setting table 15b.

  FIG. 14 shows a configuration example of the activation standby time setting table 15b. As shown in FIG. 14, the activation waiting time setting table 15b is configured by associating “time slot width of own node”, “priority”, and “waiting time” with each other. The “standby time” is set according to the time slot width of the own node.

  In FIG. 14, “the time slot width of the own node” is the size of the time slot width of the own node when the reference time slot width is “1”.

  For example, in FIG. 14, the case of “own node time slot width: 3” is “priority: 1” and “standby time: 0”, and the case of “own node time slot width: 2” is “priority: 2”. ”,“ Standby time: 1 frame period ”, and“ priority: 3 ”and“ standby time: 2 frame period ”in the case of“ own node time slot width: 1 ”.

  Note that the activation time setting means 15 is not limited to setting the priority and standby time according to the actually allocated time slot width. For example, the startup time setting means 15 sets the priority and standby time according to the average transmission data amount. It may be determined.

(B-2) Operation of the Second Embodiment Next, the startup time setting process in the communication timing control device 10B of the present embodiment will be described with reference to FIG.

  First, when a time slot for data transmission is obtained by the communication timing calculation means 12, the time slot width of the own node is measured and held by the time slot width holding means 21.

  The activation time setting unit 15 acquires the time slot width of the own node held in the time slot width holding unit 21 during the communication timing control (F301), and refers to the activation standby time setting table 15b. The priority corresponding to the time slot width is determined (F302).

  Further, the activation time setting means 15 refers to the activation standby time setting table 15b, sets the activation standby time according to the priority, sets the activation time for starting the communication timing control, and holds it (F303). .

  For example, if the time slot width of the own node is “3”, “standby time is set to 0”, and if the time slot width is “2”, “wait time is set to 1”, and the time slot width is “1”. Then, “standby time is set to 2”.

  Note that the operation for starting the communication timing control between the nodes starts from a node having a high priority, as in the first embodiment, and a detailed description of this operation is omitted.

(B-3) Effects of the Second Embodiment As described above, according to the present embodiment, the same effects as those described in the first embodiment can be obtained.

  In addition, according to the present embodiment, when a node that wants to have a large time slot width is added later, the time slot width fluctuation maximum of a node that has already been activated becomes larger than when a node with a small time slot width is added. The potential is great.

  Therefore, in this embodiment, the history of the data transmission amount of the own node is referred to, and the start of the communication timing control is made earlier for a node that has a larger data transmission amount and needs to allocate more time slots. Since a new node that may have a small time slot width is added later, the fluctuation range of the communication timing of surrounding nodes that have already been activated is small, and the convergence time can be shortened.

(C) Third Embodiment Next, a third embodiment of the communication timing control device, the communication timing control method, the node, and the communication system of the present invention will be described with reference to the drawings.

  The present embodiment is characterized in that the communication timing control device of each node sets standby time based on routing information to the destination node of the data signal and starts communication timing control.

  Therefore, for example, it is effective when applied to a network in which data signals are intensively transmitted in one direction to a certain destination node, such as a sensor network.

(C-1) Configuration of Third Embodiment FIG. 16 is a functional block diagram showing an internal configuration of a communication timing control device 10C installed in each node of the third embodiment.

  In FIG. 16, the communication timing control device 10C of this embodiment includes a communication timing signal receiving means 11, a communication timing calculating means 12, a communication timing signal transmitting means 13, a routing information holding means 31, a startup time setting means 15, and a data communication means. 16, at least.

  The point that the routing information holding means 31 is provided instead of the neighboring node number measuring means 14 of the configuration of the first embodiment, and the function of the activation time setting means 14 by using the routing table holding means 31 are the present embodiment. Different from the first embodiment. Therefore, differences from the first embodiment will be described in detail below.

  The routing information holding unit 31 holds routing information from the transmission source node to the transmission destination node of the transmission data signal.

  Here, various methods can be applied as a method for acquiring the routing information of the transmission data signal. For example, AODV (Ad Hoc On-Demand Distance Vector) can be applied. Of course, as long as each node of the network can share the routing information of the transmission data, for example, OLSR (Optimized Link State Routing) may be adopted.

  The routing information held by the routing information holding unit 31 is information including at least the number of hops to the transmission destination node of the transmission data signal.

  Of course, other than this, for example, the next hop destination (for example, the network interface destination of the own node), the validity period, the sequence number, and the like may be held.

  The activation time setting unit 15 determines the position of the own node in the route to the transmission destination node based on the routing information of the transmission data signal held by the routing information holding unit 31, and sets the number of hops from the own node to the transmission destination node. The corresponding standby time is set, and the startup time is set.

(C-2) Operation of the Third Embodiment Next, the startup time setting process in the communication timing control device 10C of the present embodiment will be described.

  In the following, a case will be described as an example where the node 2 and the node 3 transfer transmission data having the node 1 as a transmission destination node in a network configured by arranging nodes as shown in FIG.

  First, when a time slot for data transmission is obtained by the communication timing calculation means 12 and the routing information of the transmission data signal is given by a predetermined routing method, the routing information holding means 31 obtains the routing information of the transmission data signal. Hold.

  The activation time setting unit 15 checks the number of remaining hops to the destination node based on the routing information of the transmission data signal held by the routing information holding unit 31 while the communication timing control is being performed. Then, the priority corresponding to the number of hops to the transmission destination node is determined with reference to the activation waiting time setting table 15c (F402). Here, when there are multiple routes to the destination node, the number of remaining hops may be averaged and held, or the minimum number of hops among the remaining number of hops may be held. Good.

  Further, the activation time setting means 15 refers to the activation standby time setting table 15c, sets the activation standby time according to the priority, sets the activation time for starting the communication timing control, and holds it (F403). .

  For example, in FIG. 17, in node 3, the number of hops to node 1 that is the transmission destination node is “2 hops”, so “priority: 2” and “standby time: 1 frame period”. .

  For example, in the node 2, the number of hops to the node 1 as the transmission destination node is “1 hop”, so “priority: 1” and “waiting time: 0”.

  Thus, based on the routing information held by the routing information holding means 31, the priority is increased for the node having a small number of hops to the destination node, and the communication timing control is started early.

  Note that the operation for starting the communication timing control between the nodes starts from a node having a high priority, as in the first embodiment, and a detailed description of this operation is omitted.

(C-3) Effects of Third Embodiment As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained.

  Further, according to the present embodiment, based on the routing information, the closer to the transmission destination node side, the higher the communication timing control start time is given priority. For example, when data flows in a certain direction, the reception side Since the amount of data increases, the priority is given to a node that has a lot of data shooting and has an influence on the surrounding nodes when the communication timing control is activated. Therefore, the same effect as in the second embodiment can be obtained.

  In addition, even if the data amount varies greatly and it is difficult to assign the time slot width according to the data amount, the effect of determining the start priority between the nodes can be further obtained.

(D) Fourth Embodiment Next, a communication timing control device, a communication timing control method, a node, and a communication system according to a fourth embodiment of the present invention will be described with reference to the drawings.

  In this embodiment, the communication timing control device of each node detects the addition of a new node, and in this case, the case where the communication timing control is restarted by the processing described in the first to third embodiments will be described. .

(D-1) Configuration of Fourth Embodiment FIG. 20 is a functional block diagram showing an internal configuration of a communication timing control device installed in each node of this embodiment.

  20, the communication timing control device 10D of the present embodiment includes a communication timing signal receiving unit 11, a communication timing calculating unit 12, a communication timing signal transmitting unit 13, a neighboring node number measuring unit 14, a startup time setting unit 15, and data communication. Means 16 and node addition determination means 41 are included.

  This embodiment is different from the first embodiment in that a node addition determination unit 41 is newly provided. Hereinafter, a new functional configuration by providing the node addition determination unit 41 will be described in detail. The description of the functional configuration already described is omitted.

  Although FIG. 20 shows a case where the node addition determination unit 41 is provided in the configuration of the first embodiment, the node addition determination unit 41 may be provided in the configurations of the second and third embodiments.

  The node addition determination unit 41 detects reception of a signal transmitted from a node newly added to the network, and determines addition of a new node. Further, when the node addition determination unit 41 determines to add a new node, the node addition determination unit 41 notifies the communication timing calculation unit 12 accordingly.

  Here, the method by which the node addition determination unit 41 detects a new node is by detecting a signal (this is particularly referred to as a communication start signal) transmitted first by a new node that is not in communication timing control. The communication start signal may be a communication timing signal first when the communication timing signal transmission unit 13 starts data transmission.

  When the communication timing calculation unit 12 receives the notification that the addition of a new node has been determined from the node addition determination unit 41, the communication timing control unit temporarily stops the communication timing control, and then restarts the communication timing control again after the temporary stop. To do.

(D-2) Operation of the Fourth Embodiment Next, processing for restarting communication timing control in the communication timing control device 10D of the present embodiment will be described with reference to the sequence of FIG.

  First, before a new node is added, each node exchanges communication timing signals between neighboring nodes and performs communication timing control (S501).

  During this time, as described in the first to third embodiments, the activation time setting unit 15 sets a standby time at the next activation, and starts communication timing after the standby time.

  Thereafter, when a new node that does not keep communication timing control tries to start data transmission, the new node transmits a communication start signal from the communication timing signal transmission unit 13 (S502).

  When the communication start signal transmitted by the new node arrives at the node, the communication timing signal receiving means 11 receives the communication start signal, and the node addition determining means 41 is a node that is not keeping communication timing control based on the communication start signal. (S503).

  At this time, for example, based on the transmission source address included in the communication start signal, it may be determined whether or not the signal is a node in communication control.

  When it is determined that a new node has been added in the node, the node transfers the received communication start signal to another node (S504). As a result, it is possible to notify a neighboring node that a new node that does not maintain communication timing control has been added.

  When the node addition determining unit 41 determines that a new node has been added, the communication timing calculating unit 12 temporarily stops the communication timing control, and then performs the communication timing control from the first to the third. The process is restarted by the processing described in the embodiment (S505).

  When each node receives a communication start signal of the same new node via a plurality of routes, it can be prevented from being stopped again and transferred.

  In addition, a node that newly starts data transmission does not necessarily have to transmit a communication start signal. For example, when the number of neighboring nodes that directly communicate with the own node is small, or when the amount of transmission data is small, the communication start signal may not be transmitted and surrounding nodes may not be restarted. .

(D-3) Effect of Fourth Embodiment As described above, according to the present embodiment, if a new node starts communication timing control, all nodes stop communication timing control and then have high priority. Since the data signal transmission order is reconfigured by restarting from the node, the effects described in the first to third embodiments can be obtained.

  Further, according to the present embodiment, it is possible to further obtain an effect that one node that starts communication can hardly cause fluctuations in communication timing of neighboring nodes due to a large number of neighboring nodes or a large number of data transmissions. It is done.

(E) Other Embodiments The priority determination method is not limited to the method described in the first to fourth embodiments. For example, a certain node may be determined as the highest priority node in advance, and priority may be given to a node closer to the highest priority node.

  Moreover, it is good also as a network where the node which has each communication timing control apparatus demonstrated by the 1st-4th embodiment mentioned above exists in a composite.

  In the first to fourth embodiments described above, for example, in FIGS. 2, 9, 11, and 17, it has been described that all the illustrated nodes perform data transmission. The present invention can also be applied to communication timing control and data transmission.

  The hardware configuration of the communication timing control apparatus described in the first to fourth embodiments described above is configured by a CPU, ROM, RAM, EEPROM, and the like, and the CPU executes the processing program to realize the functions described above. be able to. Further, the function of the communication timing control device may be realized as hardware.

  The above-mentioned neighboring node number measuring unit 14, time slot width holding unit 21, and node addition determining unit 41 have the same hardware configuration as the communication timing calculating unit 12 and / or the communication timing signal receiving unit 11 as necessary. It may be.

  In the second embodiment described above, the time slot width holding unit 21 may hold the transmission data amount information of the transmission data signal from the data communication unit 16.

  The present invention is not limited to a wireless communication path, and can also be applied to a wired communication path or a communication path in which a wired communication path and a wireless communication path are combined.

It is a block diagram which shows the internal structure of the communication timing control apparatus of 1st Embodiment. It is a block diagram which shows the network structure of 1st Embodiment. It is explanatory drawing (1) of the tuning between nodes in the communication system of 1st Embodiment. It is explanatory drawing (2) of the tuning between nodes in the communication system of 1st Embodiment. It is a flowchart which shows the neighboring node number measurement process of 1st Embodiment. It is explanatory drawing explaining the structural example of the receiving node list of 1st Embodiment. It is a flowchart which shows the starting time setting process of 1st Embodiment. It is explanatory drawing explaining the structural example of the starting waiting time setting table of 1st Embodiment. It is an image figure explaining a mode that the communication timing control of 1st Embodiment is started (1). It is explanatory drawing explaining the time slot formed of 1st Embodiment (1). It is an image figure explaining a mode that the communication timing control of 1st Embodiment is started (2). It is explanatory drawing explaining the time slot formed of 1st Embodiment (2). It is a block diagram which shows the internal structure of the communication timing control apparatus of 2nd Embodiment. It is explanatory drawing explaining the structural example of the starting waiting time setting table of 2nd Embodiment. It is a flowchart which shows the starting time setting process of 2nd Embodiment. It is a block diagram which shows the internal structure of the communication timing control apparatus of 3rd Embodiment. It is a block diagram which shows the network structure of 3rd Embodiment. It is explanatory drawing explaining the structural example of the starting waiting time setting table of 3rd Embodiment. It is a flowchart which shows the starting time setting process of 3rd Embodiment. It is a block diagram which shows the internal structure of the communication timing control apparatus of 4th Embodiment. It is a sequence which shows the starting time setting process of 4th Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1-9 ... Node, 10A-10D ... Communication timing control apparatus, 11 ... Communication timing signal receiving means, 12 ... Communication timing calculation means, 13 ... Communication timing signal transmission means, 16 ... Data communication means, 14 ... Neighbor node number measurement Means 15... Activation time setting means 17. Time slot width holding means 31. Routing information holding means 41. Node addition determining means.

Claims (10)

In a communication timing control device mounted on each of a plurality of nodes constituting a communication system,
Using the reception timing of the timing signal received from the other node, the transmission timing of the timing signal transmitted by the own node is determined, and the transmission of the data signal is performed based on the transmission timing and the reception timing of the timing signal from the other node. Communication timing control means for performing communication timing control for determining a time slot;
Start control means for starting execution of the communication timing control by the communication timing control means at an execution timing based on a predetermined start order assigned to each node, and
The activation control means includes
An activation order determination unit that determines an activation order for the node to execute the communication timing control based on predetermined information used in the communication timing control process and / or data signal transmission / reception process by the communication timing control unit; ,
An execution timing setting unit for setting the execution timing of the communication timing control to be executed by the communication timing control unit based on the determined activation order;
Have
The communication timing control device , wherein the activation order determination unit determines the activation order based on information on the number of other nodes that share the transmission time slot with its own node . In a communication timing control device mounted on each of a plurality of nodes constituting a communication system,
Using the reception timing of the timing signal received from the other node, the transmission timing of the timing signal transmitted by the own node is determined, and the transmission of the data signal is performed based on the transmission timing and the reception timing of the timing signal from the other node. Communication timing control means for performing communication timing control for determining a time slot;
Start control means for starting execution of the communication timing control by the communication timing control means at an execution timing based on a predetermined start order assigned to each node;
With
The activation control means includes
An activation order determination unit that determines an activation order for the node to execute the communication timing control based on predetermined information used in the communication timing control process and / or data signal transmission / reception process by the communication timing control unit; ,
An execution timing setting unit for setting an execution timing of the communication timing control to be executed by the communication timing control unit based on the determined activation order;
Have
The communication timing control device according to claim 1, wherein the activation order determination unit determines the activation order based on data amount information of a transmission data signal transmitted by the node . In a communication timing control device mounted on each of a plurality of nodes constituting a communication system,
Using the reception timing of the timing signal received from the other node, the transmission timing of the timing signal transmitted by the own node is determined, and the transmission of the data signal is performed based on the transmission timing and the reception timing of the timing signal from the other node. Communication timing control means for performing communication timing control for determining a time slot;
Start control means for starting execution of the communication timing control by the communication timing control means at an execution timing based on a predetermined start order assigned to each node;
With
The activation control means includes
An activation order determination unit that determines an activation order for the node to execute the communication timing control based on predetermined information used in the communication timing control process and / or data signal transmission / reception process by the communication timing control unit; ,
An execution timing setting unit for setting an execution timing of the communication timing control to be executed by the communication timing control unit based on the determined activation order;
Have
The communication timing control device , wherein the activation order determining unit determines the activation order based on routing information of a transfer data signal passing through the own node . The activation control means includes a node number detection unit that stops the communication timing control by the communication timing control means when detecting a change in the number of other nodes that share the transmission time slot with its own node. communication timing control apparatus according to any one of claims 1 to 3,. In the communication timing control method of the communication timing control device mounted on each of a plurality of nodes constituting the communication system,
The communication timing control means determines the transmission timing of the timing signal transmitted by the own node using the reception timing of the timing signal received from the other node, and based on the transmission timing and the reception timing of the timing signal from the other node. A communication timing control step for performing communication timing control for determining a transmission time slot of the data signal;
Activation control means possess a startup control step of starting the execution of the communication timing control by the communication timing controller, the execution timing based on the predetermined activation level allotted to each node,
The activation control means includes
An activation order determination step for determining an activation order for the node to execute the communication timing control based on predetermined information used in the communication timing control process and / or data signal transmission / reception process by the communication timing control means; ,
An execution timing setting step for setting an execution timing of the communication timing control to be executed by the communication timing control means based on the determined activation order;
Have
In the activation order determination step, the activation order is determined based on the information on the number of other nodes competing with the own node and the transmission time slot.
A communication timing control method characterized by the above. In the communication timing control method of the communication timing control device mounted on each of a plurality of nodes constituting the communication system,
The communication timing control means determines the transmission timing of the timing signal transmitted by the own node using the reception timing of the timing signal received from the other node, and based on the transmission timing and the reception timing of the timing signal from the other node. A communication timing control step for performing communication timing control for determining a transmission time slot of the data signal;
An activation control step in which activation control means activates execution of the communication timing control by the communication timing control means at an execution timing based on a predetermined activation order assigned to each node;
Have
The activation control means includes
An activation order determination step for determining an activation order for the node to execute the communication timing control based on predetermined information used in the communication timing control process and / or data signal transmission / reception process by the communication timing control means; ,
An execution timing setting step for setting an execution timing of the communication timing control to be executed by the communication timing control means based on the determined activation order;
Have
In the activation order determination step, the activation order is determined based on data amount information of a transmission data signal transmitted by the node.
A communication timing control method as described above. In the communication timing control method of the communication timing control device mounted on each of a plurality of nodes constituting the communication system,
The communication timing control means determines the transmission timing of the timing signal transmitted by the own node using the reception timing of the timing signal received from the other node, and based on the transmission timing and the reception timing of the timing signal from the other node. A communication timing control step for performing communication timing control for determining a transmission time slot of the data signal;
An activation control step in which activation control means activates execution of the communication timing control by the communication timing control means at an execution timing based on a predetermined activation order assigned to each node;
  Have
The activation control means includes
An activation order determination step for determining an activation order for the node to execute the communication timing control based on predetermined information used in the communication timing control process and / or data signal transmission / reception process by the communication timing control means; ,
An execution timing setting step for setting an execution timing of the communication timing control to be executed by the communication timing control means based on the determined activation order;
Have
In the activation order determination step, the activation order is determined based on routing information of a transfer data signal passing through the own node.
A communication timing control method characterized by the above. The activation control means includes a node number detection step of stopping the communication timing control by the communication timing control means when detecting a change in the number of other nodes that are sharing the transmission time slot with the own node. The communication timing control method according to claim 5. Node, characterized in that it comprises a communication timing control device according to any one of claims 1-4. A communication system comprising a plurality of nodes according to claim 9 .

Images