JP4389949B2 - Communication timing control device, communication timing control method, node, and communication system - Google Patents

Description

  The present invention relates to a communication timing control device, a communication timing control method, a node, and a communication system, for example, a time division wireless network in which each node autonomously controls transmission timing so that data collision does not occur between a plurality of nodes. It can be applied to the system.

  In wireless communication, as a method of adjusting transmission timing so that data collision does not occur between a plurality of nodes, each node as described in Patent Document 1 autonomously controls transmission timing while exchanging timing signals. There is a method.

  In the method described in Patent Document 1, communication timing signals (impulse signals) are exchanged between a plurality of nodes arranged in a network, and based on the communication timing signals, each node is self-registered so that a transmission data signal does not collide. This is a method for autonomously controlling and determining the time slot.

Here, each node transmits a communication timing signal almost periodically. In addition, a data transmission time slot is secured by receiving a communication timing signal from a nearby node and adjusting the communication timing of the own node in consideration of the reception timing.

  Here, even when the frame period serving as a reference determined by the natural frequency parameter ω is uniform among the nodes, there is an error between the clocks of the respective nodes, so that the frame period cannot be completely unified. However, as described above, the frame period can be made uniform among nodes by exchanging communication timing signals.

A node that intends to transmit a data signal to the network transmits a data signal by transmitting a communication timing signal from its own node to immediately before another node transmits a communication timing signal. Can do.
JP 2005-94663 A

  By the way, for example, nodes constituting the communication system may be battery-driven, and power saving is desired in such nodes. In general, power saving can be achieved by stopping a node during a time when data signals are not transmitted and received.

  However, as described above, in the case of a communication system that applies a method in which each node autonomously controls transmission timing while exchanging timing signals, when any node is stopped, the node becomes a neighboring node. Timing adjustment cannot be performed, and the timing adjustment is performed assuming that one or more nearby nodes do not have the stop node. In such a state, if there is an error between the clocks of each node, a frame period synchronization shift occurs between the node in the stopped state and the neighboring node in the active state.

  For this reason, when the node returns from the stop state, timing adjustment with the neighboring node has not been performed, so timing adjustment must be performed, and during the timing adjustment (transient state) Data transmission possible time (data transmission bandwidth) decreases.

  Not only when the node is temporarily stopped, but also when a new node is added to the network, if the new node starts sending the communication timing signal without considering the timing of the already active node, As in the case of returning, a transient state occurs, and as a result, the data transmission available time (data transmission bandwidth) of the new node is reduced.

  Therefore, a communication timing control device, a communication timing control method capable of ensuring as much as possible the data transmission possible time (data transmission bandwidth) of the node immediately after returning from the stopped state (sleep state) or newly added node, Nodes and communication systems are desired.

1st this invention is the communication timing control apparatus provided in each of the some node which comprises a communication system, Comprising: The communication from an own node is utilized using the reception timing of the communication timing signal from another node. In a communication timing control apparatus that determines a transmission timing of a timing signal and determines a time for transmitting a data signal from the own node based on the transmission timing and a reception timing of a communication timing signal from another node. An active state in which communication timing is controlled while exchanging timing signals with other nodes and data signals are exchanged with other nodes, and (b) a sleep state in which no exchange of the communication timing signals and data signals is performed. (C) Stop the transmission operation from its own node, and communicate from other nodes Have the respective units operation control means for controlling so each unit in either state of semi-active state to operate to determine the transmission start time of the communication timing signal from its own node at the time of transition to the active state by performing the uptake of timing signals And (d) each part operation control means changes the state in the order of sleep state, semi-active state, and active state, and (e) each part operation control means is at least when its own node is in the semi-active state. The transmission start time is determined in consideration of the timing relationship between the transmission timing of the local node and the transmission timing of the other node immediately before the previous transition of the local node to the sleep state .

  A node according to a second aspect of the present invention includes the communication timing control apparatus according to the first aspect of the present invention.

  A communication system according to a third aspect of the present invention is characterized by including a plurality of nodes according to the second aspect of the present invention.

A fourth aspect of the present invention is a communication timing control method executed by each of a plurality of nodes constituting a communication system, using a reception timing of a communication timing signal from another node, and a communication timing signal from the own node In a communication timing control method for determining a transmission time of a data signal from its own node based on the transmission timing and a reception timing of a communication timing signal from another node, (a) each part operation control means (B) The operation control means of each unit (c) controls the communication timing while exchanging the communication timing signal with another node, and also transmits and receives the data signal with the other node, and A sleep state in which no transmission / reception of communication timing signals and data signals is executed, Each part in one of the semi-active states that determines the transmission start time of the communication timing signal from its own node when the transmission operation from the other node is stopped and the communication timing signal is taken in from another node to shift to the active state (D) Each part operation control means changes the state in the order of sleep state, semi-active state, and active state. (E) Each part operation control means has its own node in a semi-active state. The transmission start time is determined in consideration of the timing relationship between the transmission timing of the local node and the transmission timing of another node at the time immediately before the local node transits to the sleep state. And

  According to the communication timing control device, the communication timing control method, the node, and the communication system of the present invention, the semi-active state is provided, the timing of the other node is observed, and the timing of the communication timing signal when transitioning to the active state is performed. Thus, the data transmission available time (data transmission bandwidth) of the node immediately after returning from the sleep state to the active state or newly added node can be quickly secured.

(A) Main Embodiment Hereinafter, an embodiment 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 in detail with reference to the drawings.

(A-1) Configuration of Embodiment FIG. 1 is a block diagram illustrating an internal configuration of the node 10 of the embodiment. In the communication system of the embodiment, a plurality of nodes having the internal configuration shown in FIG. 1 are distributed.

  In FIG. 1, the node 10 includes a communication timing signal reception unit 11, a communication timing signal transmission unit 12, a communication timing calculation unit 13, a data communication unit 14, and an on / off control unit 15.

  The communication timing signal receiving means 11, the communication timing signal transmitting means 12, the communication timing calculating means 13 and the on / off control means 15 constitute a communication timing control device.

  Here, the communication timing signal receiving unit 11, the communication timing signal transmitting unit 12, the communication timing calculating unit 13, and the data communication unit 14 have functions similar to those of the node described in Patent Document 1. The communication timing calculation unit 13 corresponds to the communication timing calculation unit and the tuning determination unit disclosed in Patent Document 1.

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

The communication timing calculation means 13 forms a phase signal that defines the communication timing at the node based on the signal given from the communication timing signal reception means 11 in an active state to be described later. Here, assuming that the node is the node i and the phase value of the phase signal at time t is θi (t), the communication timing calculation means 13 causes the phase signal θi ( t) is changed. The expression (1) is an expression modeling nonlinear vibration, but an expression modeling other nonlinear vibration can also be applied. Further, the phase signal θi (t) can be regarded as a state variable signal of the node.

  Expression (1) represents a rule for changing the rhythm of nonlinear vibration of the phase signal θi (t) of the own node i in accordance with the signal given from the communication timing signal receiving means 11. In the expression (1), the first term ω (natural angular frequency parameter) on the right side is a basic change rhythm (corresponding to “basic velocity (basic frame period) 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 for the entire system. The function Pk (t) represents the communication timing signal received from the neighboring node k (k is assumed to be 1 to N), and the function R (θi (t), σ (t)) is obtained from other nodes. This is a phase response function that expresses a response characteristic that changes its basic rhythm in response to reception of a communication timing signal. For example, it is in accordance with equation (2).

Expression (2) represents that the phase response function is defined by 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.

  Non-linear characteristics in which neighboring nodes are in opposite phases (vibration phase is inverted phase) are realized, and collision avoidance is attempted using the characteristics. That is, an appropriate time relationship (time difference) is to be formed at the timing when the phase signal value of each node becomes the same value so that the transmission timing of the communication timing signal between neighboring nodes does not collide.

  In the equation (2), the constant term π [rad] representing the function σ (t) functions as a non-linear characteristic in which neighboring nodes are out of phase with each other, and the random noise function φ (t) 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 to deal with a phenomenon that the system does not reach the target stable state (optimal solution) and falls into another stable state (local solution). Because.

  In the equation (2), the form using the sine function is shown as the simplest example of the phase response function R (θi (t), σ (t)), but other functions may be used as the phase response function. good. 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, neighboring nodes are not in antiphase but in different phases. Function.

  The meaning of the above-described function of the communication timing calculation means 13 will be described in detail with reference to FIG. The state change shown in FIG. 2 also relates to the function of the communication timing signal transmission unit 12.

  FIG. 2 shows a relationship formed between a target node (own node) and a neighboring node (other node) j when attention is paid to a certain node i, that is, a phase relationship between the respective nonlinear vibration rhythms. Shows how the changes over time.

  FIG. 2 shows a case where there is one neighboring node j for the node of interest i. In FIG. 2, the motion of two mass points rotating on a 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 try to be in opposite phases to each other. As shown in FIG. 2 (a), the phases of the two mass points are close to each other in the initial state. However, with the passage of time, the state (transient state) shown in FIG. 2B changes to a steady state in which the phase difference between the two mass points is approximately π as shown in FIG. 2C.

  Each of the two mass points rotates with the natural angular frequency parameter ω as a basic angular velocity (corresponding to a basic velocity for transitioning its own operation state). Here, when an interaction based on transmission / reception of a communication timing signal occurs between nodes, these mass points change (slow and steep) 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, when each node transmits a communication timing signal when the phase is a predetermined phase α (for example, α = 0), the transmission timing in each node forms an appropriate time relationship. .

  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. For example, a case where a node in a sleep state, which will be described later, changes to an active state via a semi-active state corresponds to such an additional case. At the time of such addition, the steady state temporarily 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. For example, a case where an active node described later changes to a sleep state corresponds to such a decrease.

  The communication timing calculation unit 13 determines the transmission timing of the communication timing signal based on the obtained phase signal θi (t) and instructs the communication timing signal transmission unit 12. That is, when the phase signal θi (t) reaches a predetermined phase α (0 ≦ α <2π), the transmission of the communication timing 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. 2, since the phase signals θi (t) and θj (t) in the steady state are shifted by π at the node i and the node j, the entire system is unified to α = 0. However, the transmission timing of the communication timing signal from the node i and the transmission timing of the communication timing signal from the node j are shifted by π.

  The communication timing signal transmission unit 12 transmits a communication timing signal based on a transmission request given from the communication timing calculation unit 13 when the phase signal θi (t) of the communication timing calculation unit 13 reaches a predetermined phase α. It is.

  Note that the semi-active state calculation unit 13a of the communication timing calculation unit 13 determines the transmission timing when resuming transmission of the communication timing signal in a semi-active state described later regardless of whether the phase signal θi (t) is a predetermined phase. Thus, a transmission request is given to the communication timing signal transmission means 12.

  The tuning determination unit in the communication timing calculation unit 13 is configured so that mutual adjustment of the transmission timing of the communication timing signal performed between the own node and one or a plurality of neighboring nodes is “transient state” (see FIG. 2B) or It is determined which state is “steady state” (see FIG. 2C) (tuned determination is performed). The tuning determination unit observes the reception timing of the communication timing signal and the transmission timing of the communication timing signal from its own node, and there is a sufficient time difference between the transmission timings of a plurality of nodes that exchange the communication timing signal. When it is stable, it is determined to be “steady state”. The tuning determination unit uses the phase signal θi (t) as a signal for capturing the transmission timing of the communication timing signal from the own node.

  When the tuning determination result indicates “steady state”, the tuning determination unit determines a time slot from the node for each cycle of the phase signal θi (t) and instructs the data communication unit 14.

  The data communication unit 14 has a function of transmitting a data signal to the network within the time slot notified from the tuning determination unit and receiving a data signal arriving from the network outside the time slot period of the node. Yes. In FIG. 1, an information processing configuration that is a data signal output source and a reception data signal supply destination is omitted.

  The on / off control means 15 newly provided in this embodiment has a function of performing on / off control of the power supplies of the respective functional blocks 11 to 14 of the node. The on / off control means 15 can not only perform on / off control of all the functional blocks 11 to 14 at the same time but also individually turn on / off the functional blocks. Note that the control target of the on / off control means 15 may include an information processing configuration that is a data signal output source and a reception data signal supply destination.

  The timing at which the on / off control means 15 performs the on / off control is not limited. For example, on / off may be performed with a period longer than a reference frame period in communication timing calculation. For example, the on / off control unit 15 operates when the node operates with a battery as a power source, and the transmission time and reception time of the data signal from the node 10 are determined (for example, every 10 minutes). In accordance with that, the power supply of each of the functional blocks 11 to 14 is controlled on / off.

  Under the control of the on / off control means 15, the power on / off states of the functional blocks 11 to 14 in the node 10 take one of the three states shown in FIG. The three states are an active state, a sleep state, and a semi-active state.

  The active state is a state in which all the functional blocks 11 to 14 (and 15) are operable. In this active state, the node 10 can perform transmission / reception of communication timing signals and transmission / reception of data signals with neighboring nodes. That is, in the active state, the communication timing signal receiving unit 11, the communication timing signal transmitting unit 12, the communication timing calculating unit 13, and the data communication unit 14 perform the same operations as the existing ones.

  The sleep state is a state in which the functional blocks 11 to 14 other than the timer in the on / off control means 15 are stopped. The on / off control means 15 manages the time for returning (turning on) the functional blocks 11 to 14 stopped in the sleep state. That is, in the sleep state, the communication timing signal reception unit 11, the communication timing signal transmission unit 12, the communication timing calculation unit 13, and the data communication unit 14 do not operate at all.

  The semi-active state is a state in which the communication timing signal receiving unit 11 and the communication timing calculating unit 13 are activated and the communication timing signal transmitting unit 12 is stopped. In the semi-active state, the data communication means 14 may be activated or stopped. However, in this state, data transmission is not performed, so that the data communication unit 14 may be stopped. In addition, since the transmission processing of the communication timing signal and the data signal is not performed and the processing amount is small, the clock speed may be lowered in the semi-active state. As described above, since the processing amount is small in the semi-active state and some of the functional blocks are operating, power saving can be achieved. The communication timing signal receiving means 11 performs the same operation as in the active state even in the semi-active state. On the other hand, the semi-active state calculation unit 13a of the communication timing calculation unit 13 performs an operation different from the active state in the semi-active state. This operation will be clarified in the operation section.

  The communication timing calculation unit 13 may automatically recognize the semi-active state based on the power on / off of the communication timing signal receiving unit 11 and the communication timing signal transmitting unit 12, and may turn on / off. The semi-active state may be recognized by an on instruction from the control unit 15, and the active state may be automatically recognized by the end of the processing by the semi-active state calculation unit 13a. Furthermore, the on / off control means 15 may instruct the communication timing calculation means 13 by distinguishing between the semi-active state and the active state.

  FIG. 3 shows an example of state transition. The example shown in FIG. 3 shows an example in which a transition can be made only from the sleep state to the semi-active state, from the semi-active state to the sleep state or the active state, and from the active state to the sleep state or the semi-active state. Yes. The present invention is not limited to the example illustrated in FIG. 3, and each state may be changed only cyclically, such as a sleep state, a semi-active state, an active state, and a sleep state.

(A-2) Operation of the First Embodiment Next, the operation of the node 10 of the embodiment will be described. In particular, the operation of the communication timing calculation unit 13 and the on / off control unit 15 will be mainly described.

  FIG. 4 is a flowchart illustrating the control operation in the power on / off state in the node 10 according to the embodiment. That is, the operation of the node 10 in the process of transitioning from the active state to the sleep state and then returning to the active state is shown.

  In the following, the operation from the time when the node N2 transitions to the sleep state when the four nodes N1, N2, N3, and N4 are performing transmission and reception of the communication timing signal in the steady state will be described with reference to FIG. This will be described with reference to the timing chart.

  In the initial state before the start of a series of transitions, as shown in FIG. 5A, all nodes N1 to N4 are in an active state, and communication timing signals are transmitted in the order of nodes N1, N2, N3, and N4. The time slots allocated to the nodes N1, N2, N3, and N4 are periods obtained by dividing one frame period T into four equal parts.

[Step S1]
The on / off control means 15 of the node N2, for example, sets a sleep start time timer internally, and when the sleep start time is reached, stops all the functional blocks 11 to 14 in the node N2 and shifts to the sleep state. Let

  In the active state, the communication timing calculation means 13 updates and stores a transmission timing signal in a nonvolatile recording medium such as an EEPROM as the transmission time immediately before the transmission timing signal. Even after the transition to the sleep state, the immediately preceding transmission time is continuously stored and can be used in step S3 described later.

[Step S2]
When the on / off control means 15 of the node N2 transitions from the active state to the sleep state, it sets a return time to the active state therein and maintains the sleep state until this return time.

  Due to the transition of the node N2 to the sleep state, as shown in FIG. 5B, the three nodes N1, N3, and N4 are in a state of exchanging communication timing signals. As a result, the “stationary state at 4 nodes” so far changes to “transient state at 3 nodes”, and the time slot of each node is divided into three times so that the time slot divided into 3 equals the time slot of each node. The nodes N1, N3 and N4 are gradually adjusted in phase (see FIG. 2).

[Step S3]
At the node N2, when the active state return time comes, the on / off control means 15 restores the functional blocks 11 and 13 except the communication timing signal transmission means 12 and the data communication means 14. In other words, for the functional blocks 12 and 14 that perform a process of giving signals to the other nodes N1, N3, and N4 and recognizing the existence of the own node N2, the power off is continued and the other functional blocks 11 and 13 is restored. This means that the transition to the semi-active state is made.

  The semi-active state calculation unit 13a of the communication timing calculation unit 13 uses the information on the transmission time of the communication timing signal immediately before the transition to the sleep state and the reference frame period (T), and the communication timing signal from the own node N2. The candidate for the resume transmission time is determined. For example, as a candidate for resuming transmission time, among the times obtained by adding a time that is an integral multiple of the frame period T to the transmission time of the immediately previous communication timing signal, the time difference from the current time is close to the current time within a predetermined range. Time. For example, a future time within a range where the time difference from the current time is 1 frame or more and less than 2 frames may be used as a candidate. Further, in consideration of processing delay and the like, a future time with more margin may be used as a candidate.

[Step S4]
The communication timing signal receiving means 11 receives the communication timing signals from the other nodes N1, N3, and N4 after the power-on is resumed, and inputs them to the communication timing calculating means.

[Step S5]
Whether the restart transmission time candidate determined in step S3 is appropriate is confirmed using reception timings such as communication timing signals from other nodes N1, N3, and N4.

  As the confirmation rule, (R1) When the future reception timing is estimated from the reception timing of the communication timing signal from the other nodes N1, N3, and N4, the other node that will transmit immediately before the candidate for the restart transmission time, The combination of the other nodes that will be transmitted immediately after the resume transmission time candidate is the same as the combination of the other nodes before and after the transmission timing before sleep, (R2) The time difference of the transmission time is the maximum of the time difference of the transmission time of the communication timing signal, (R3) the time difference between the candidate of the restart transmission time and the transmission timing of the other nodes before and after is equal to or greater than the threshold time, Etc. may be applied, and when all of these are satisfied, it may be determined to be appropriate.

  In the “transient state at 3 nodes” described above that has not reached the “steady state at 3 nodes”, the timing difference between the nodes N1 and N3 that sandwiched the timing of the own node N2 immediately before the transition to the sleep state is roughly Therefore, as described above, the timing immediately before the transition to the sleep state is respected, and the confirmation also considers the timing relationship immediately before the transition to the sleep state.

  Only the combination of (R1) and (R3) may be applied as a confirmation rule, or a rule from another viewpoint may be introduced.

  For example, if there is a slight difference between the clock frequencies of the operation clocks of the node N1 and the node N2 that has been semi-activated, the frame period will not match if strictly observed, and the time obtained by adding an integral multiple of the frame period T will be obtained. If the sleep period is long, the restart transmission time candidates that are close to the timing of the node N1 (may be approached or exceeded) by that period or move away from the timing of the node N1 (go away from the node) The timing of N3 may be exceeded).

  FIG. 5C shows a case where the candidate for the restart transmission time is too close to the timing of the node N1, and in this case, transmission of the communication timing signals of the nodes N1 and N2 may collide if restarted. Therefore, it is determined that the resume transmission time candidate is not appropriate. FIG. 5D shows a case where the candidate for the restart transmission time has a certain timing difference from the timings of the nodes N1 and N3. In this case, it is determined that the candidate for the restart transmission time is appropriate. . FIGS. 5C and 5D show the timings of other nodes N1, N3, and N4 predicted from the reception timing.

  If the resume transmission time candidate is appropriate, the resume transmission time candidate is determined as the resume transmission time. If the candidate for the restart transmission time is not appropriate, the restart transmission time is determined according to a predetermined rule. For example, for the nodes N1 and N3 that sandwiched the timing of the own node N2 immediately before the transition to the sleep state, the intermediate time between the transmission timings predicted from the reception timing of the communication timing signal is determined as the restart transmission time. . Alternatively, regardless of the type of another node, an intermediate position within a time in which the time difference between successive transmission timings is the maximum is determined as the restart transmission time.

[Step S6]
When the resumption transmission time of the communication timing signal is determined, the semi-active state calculation unit 13a of the communication timing calculation means 13 notifies the on / off control means 15 of the resumption transmission time, and the on / off control means 15 receives the communication timing signal. The transmission unit 12 and the data communication unit 14 are turned on. This means that it has transitioned to the active state.

  The communication timing calculation unit 13 causes the communication timing signal transmission unit 12 to transmit a communication timing signal at the restart transmission time, and thereafter performs an operation in an active state.

[Step S7]
The node N2 performs communication timing control while exchanging the communication timing signal, and starts transmission of the data signal when the steady state is reached.

  If it is determined that a sufficient time slot width is allocated to the own node N2 in the semi-active state, the data in the time slot of the own node N2 immediately after the active state is entered (even in the transient state). Signal transmission may be started.

(A-3) Effect of Embodiment According to the above-described embodiment, in addition to the active state and the sleep state, the semi-active that performs only the process of calculating the restart transmission time (in other words, the time slot position) of the communication timing signal after the return Since the node that is set to return from the sleep state transitions to the active state via the semi-active state, the effect of timing adjustment on the other nodes in the active state is reduced during the return, and the transient state Time can be shortened. As a result, the effect of shortening the data transmission bandwidth reduction time seen in the entire network can be obtained.

  In the semi-active state, since no communication timing signal or data signal is transmitted, it is not necessary to start all the functional blocks, and the processing amount is small, so that the clock speed can be lowered. Therefore, the effect that the transient state can be reduced while achieving power saving can be obtained.

(B) Other Embodiments The above embodiment is based on the conventional technique described in Patent Document 1, but is not the conventional technique described in Patent Document 1, and exchanges communication timing signals. Of course, the present invention can be applied to other techniques that autonomously assign time slots periodically based on the interaction based on them.

  In the description of the operation of the above-described embodiment, a case where transition is made in the active state → sleep state → semi-active state → active state is shown, but other transition orders may be used.

  For example, when it is known that the sleep period is equal to or less than a predetermined time in advance, the active state is changed to the semi-active state without changing from the active state to the sleep state, and the active state is returned from the semi-active state. Anyway. In the semi-active state in such a case, the intermediate position of the timings of the two other nodes having timings that are in succession to the timing immediately before the sleep of the own node is constantly monitored, and the resume transmission time candidate Then, when it is time to make a transition to the active state, the processing after step S16 in FIG.

  Also, for example, when the sleep period is not known in advance, when a half-active state is set within a predetermined time from when the sleep state is desired and a request for returning to the active state does not occur even if the predetermined time is exceeded You may make it transfer to a sleep state. In this case as well, the method of the above-described embodiment can be applied as a method for determining a candidate for the restart transmission time.

  In the above embodiment, the present invention is applied when the active state is intermittently transited to the sleep state. However, the present invention is also applied when a node is newly added to the network. Also good. That is, the additional node does not transmit the communication timing signal immediately after the power is turned on, but transits to the active state after going through a state similar to the semi-active state of the above embodiment. In a state similar to the semi-active state, the transmission start time is determined while looking at the timing difference with the transmission timing of the communication timing signal of the other node, and the operation in the active state is executed immediately before the transmission start time. For example, the transmission start time is determined to be an intermediate time of the maximum time slot width. In addition, the term “sleep state” in the claims includes a state in which no processing is performed on the additional node, and the term “semi-active state” in the claims includes the state regarding the additional node, A state similar to the semi-active state of the above embodiment is included.

It is a block diagram which shows the internal structure of the node of embodiment. It is explanatory drawing of the principle operation | movement of the communication timing calculation means of embodiment. It is a state transition diagram which shows three power supply ON / OFF states in the node of embodiment. It is a flowchart which shows the control operation | movement of the power supply on / off state in the node of embodiment. It is a timing chart which shows the relationship between the change of the power-on / off state in the node with embodiment, and the change of the time slot of each node.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Node, 11 ... Communication timing signal receiving means, 12 ... Communication timing signal transmission means, 13 ... Communication timing calculation means, 13a ... Semi-active state calculation part, 14 ... Data communication means, 15 ... On / off control means.

Claims (5)

A communication timing control device provided in each of a plurality of nodes constituting a communication system, which determines the transmission timing of a communication timing signal from its own node using the reception timing of a communication timing signal from another node In the communication timing control device for determining the time for transmitting the data signal from the own node based on the transmission timing and the reception timing of the communication timing signal from the other node,
While controlling the communication timing while exchanging the communication timing signal with other nodes, an active state of exchanging data signals with other nodes,
A sleep state in which no transmission / reception of the communication timing signal and the data signal is performed;
One of the semi-active states that determines the transmission start time of the communication timing signal from the own node when the transmission operation from the own node is stopped and the communication timing signal from the other node is taken in and shifted to the active state Each part operation control means for controlling each part to operate in
Each of the above-mentioned operation control means transitions the state in the order of sleep state, semi-active state, active state ,
When each node operation control means is in a semi-active state, at least the timing relationship between the transmission timing of the local node and the transmission timing of another node at the time immediately before the local node transitions to the sleep state is obtained. A communication timing control apparatus that determines a transmission start time in consideration of the above .   2. The communication timing control device according to claim 1, wherein said operation control means reduces the processing clock speed defining the processing speed of each unit in a semi-active state. Node, characterized in that it comprises a communication timing control device according to claim 1 or 2. A communication system comprising a plurality of nodes according to claim 3 arranged therein. A communication timing control method executed by each of a plurality of nodes constituting a communication system, using a reception timing of a communication timing signal from another node, determining a transmission timing of a communication timing signal from the own node, In the communication timing control method for determining the time for transmitting the data signal from the own node based on the transmission timing and the reception timing of the communication timing signal from the other node,
Each part operation control means, each part operation control means,
While controlling the communication timing while exchanging the communication timing signal with other nodes, an active state of exchanging data signals with other nodes,
A sleep state in which no transmission / reception of the communication timing signal and the data signal is performed;
One of the semi-active states that determines the transmission start time of the communication timing signal from the local node when the transmission operation from the local node is stopped and the communication timing signal is captured from the other node to shift to the active state To control each part to work ,
Each of the above-mentioned operation control means transitions the state in the order of sleep state, semi-active state, active state ,
When each node operation control means is in a semi-active state, at least the timing relationship between the transmission timing of the local node and the transmission timing of another node at the time immediately before the local node transitions to the sleep state is obtained. A communication timing control method characterized by determining a transmission start time in consideration of the above .

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