JP4341672B2 - Communication timing control system and communication timing control method - Google Patents

Description

The present invention relates to a communication timing control system and a communication timing control method. For example, when a large number of nodes and mobiles distributed in a space such as a sensor network perform data communication with each other, communication data due to radio wave interference or the like. The present invention can be applied to an apparatus, a method, a node, and a communication system for avoiding collisions.

  Patent Documents 1 to 7 describe a technique related to communication timing control that avoids a communication data transmission collision by autonomously distributing time slot allocation without requiring a centralized management server. ing.

  In the communication timing control method described in Patent Literature 1 to Patent Literature 7, each node periodically transmits and receives an impulse signal (a control signal indicating the transmission timing of the own node) to and from neighboring nodes, thereby mutual communication timing. Make adjustments. This realizes time slot allocation that divides one period (impulse signal transmission period) between nodes in the impulse signal reachable range (hereinafter referred to as the interaction range). Note that the impulse signal does not necessarily mean a signal having an impulse-like waveform, and can be configured by a packet or the like as with a general control signal. Therefore, here, the impulse signal is referred to as a timing control signal.

  By the way, as one application mode of the communication timing control method as described above, there is a wireless sensor network, for example.

  In general, a wireless sensor network often includes a network that collects observation data sensed by individual sensor nodes at a sink node. That is, each sensor node wirelessly transmits observation data to neighboring nodes, and the reception node finally performs an operation (multi-hop communication) for transferring the reception data to another node, thereby finally obtaining a sink node. A network that allows observation data to reach is constructed.

  In such a network, traffic concentrates on nodes existing in the vicinity of the sink node. Therefore, congestion (communication data congestion) occurs if the neighboring node of the sink node does not secure a radio band (channel occupation time) that is large enough to process traffic. In other words, each sensor node needs to transmit observation data received from other nodes (data to be transferred) in a certain period (transmission cycle) with the observation data of its own node and control information such as the destination added. There is. When the “data amount that needs to be transmitted in a certain period” exceeds the “data amount that can be transmitted in the same period”, the observation data to be transmitted accumulates and congestion occurs.

  Therefore, when the techniques disclosed in Patent Documents 1 to 7 are used, the transmission period of the timing control signal, that is, the time slot allocation period (corresponding to the above-described fixed period) is considered in consideration of the above points. It is necessary to set the size so that the neighboring nodes of the node can process the traffic.

  On the other hand, in the above network, the communication delay increases as the time slot allocation period increases. Here, the communication delay means the time required for the observation data of each sensor node to reach the sink node.

  Therefore, in order to minimize the communication delay and prevent congestion, the designer needs to estimate the traffic generated in the network in advance and set the time slot allocation period to an appropriate value.

JP 2005-94663 A JP 2006-074617 A JP 2006-0774619 A JP 2006-157438 A JP 2006-157441 A Japanese Patent Application Laid-Open No. 2006-211585 Japanese Patent Laid-Open No. 2006-211564

  However, the method in which the designer fixedly sets the time slot allocation period as described above functions effectively when the network node configuration is fixed and the generated traffic does not fluctuate. When this occurs, there is a problem that the setting must be changed manually each time.

  For example, when a network is expanded later by adding a node to a certain network, the traffic generated generally increases, so that congestion is not maintained with the period of time slot allocation optimized for the original network. appear. Therefore, when expanding the network, the designer is forced to change the setting in the field, and the problem of lack of scalability becomes obvious.

  Therefore, for the above problems, communication timing control that can realize a function for the network to autonomously determine an appropriate value according to the situation, instead of setting the time slot allocation period as a fixed parameter. There is a need for an apparatus, a communication timing control method, a communication timing control program, a node, and a communication system.

In order to solve such a problem, a communication timing control system according to a first aspect of the present invention includes a transmission timing of a timing control signal received from one or a plurality of other nodes by each of a plurality of nodes constituting the communication system, Communication timing calculation means for calculating a time slot in which the own node transmits a data signal in a predetermined operation cycle based on mutual adjustment with the transmission timing of the node timing control signal , and (1) an operation among a plurality of nodes Based on the data amount information of the transmission data included in the timing control signal received from (1-1) 1 or a plurality of other nodes by the first node that determines the cycle, the update cycle information of the operation cycle by a predetermined method And (1-2) update cycle information of the operation cycle determined by the cycle determination unit. Including the control signal and a timing control signal transmitting means for transmitting to one or more other nodes, (2) a first one or more second nodes except the node (2-1) communication timing calculated The means updates the operation cycle using the update cycle information of the operation cycle included in the timing control signal received from the first node, and calculates the time slot of the data signal of the own node in the updated operation cycle. It is characterized by that.

In the communication timing control method of the second aspect of the present invention, the transmission timing of the timing control signal received by each of the plurality of nodes constituting the communication system from one or more other nodes and the transmission timing of the timing control signal of the own node And a communication timing calculation means for calculating a time slot in which the own node transmits a data signal in a predetermined operation cycle based on mutual adjustment, and (1) a first determination of the operation cycle among a plurality of nodes. (1-1) The cycle determination means determines the update cycle information of the operation cycle by a predetermined method based on the data amount information of the transmission data included in the timing control signal received from one or more other nodes. And (1-2) a timing control signal transmission unit that updates the operation cycle determined by the cycle determination unit. A timing control signal transmitting step of including information in a timing control signal and transmitting the information to one or more other nodes. (2) One or more second nodes other than the first node are (2-1 ) The communication timing calculation means updates the operation cycle using the update cycle information of the operation cycle included in the timing control signal received from the first node, and sets the time slot of the data signal of the own node in the updated operation cycle. It has the process to calculate, It is characterized by the above-mentioned.

  According to the present invention, it is possible to realize a function in which the network autonomously determines an appropriate value according to the situation, instead of setting the time slot allocation period as a fixed parameter.

(A) First Embodiment A first embodiment using the communication timing control system apparatus and the communication timing control method of the present invention will be described below with reference to the drawings.

  The first embodiment uses a communication control apparatus, a communication control method, a communication control program, a node, and a communication system according to the present invention in a wireless communication network (communication system) configured to include a plurality of nodes. An embodiment in which each node calculates communication timing based on its own timing control signal will be described.

  In the first embodiment, a wireless sensor network that collects data by transferring observation data sensed by individual sensor nodes to a sink node by multi-hop will be described as an example.

(A-1) Configuration and Operation of First Embodiment (A-1-1) Configuration of Wireless Communication Network FIG. 2 is an overall configuration diagram of a wireless communication network (wireless sensor network) NT of the first embodiment. is there. In FIG. 2, the wireless communication network NT according to the first embodiment includes a large number of nodes A and sink nodes S.

  In FIG. 2, a solid circle centered on the sink node S indicates a spatial range in which the data signal transmitted from the sensor node A reaches the sink node S directly (that is, in one hop) without passing through the relay node. Show. Further, the area excluding the solid circle from the dotted circle existing around it is a space in which the data signal transmitted from the sensor node A reaches the sink node S via one relay node (that is, in two hops). Indicates the range.

  In FIG. 2, a dotted circle centered on the sensor node A further outside the two types of circles (solid and dotted circles) indicates a first neighboring node range of the sensor node A. That is, the inner dotted circle indicates the first neighboring node range of the sensor node A, and is the data signal reachable range in the first embodiment. An outer dotted circle indicates a second neighboring node range of the sensor node A, and is a reach range of the timing control signal in the first embodiment. As described above, in the first embodiment, it is assumed that the radio wave arrival range of the timing control signal is about twice the radio wave arrival range of the data signal.

  Here, the timing control signal is a control signal indicating the transmission timing of the own node. The timing control signal may be, for example, a signal having an impulse-like waveform (a concept including a waveform-shaped signal), but is not limited thereto, and is a signal composed of a packet or the like. Good.

  Each of the many sensor nodes A is provided with a sensor in advance, observes observation data periodically or constantly, and wirelessly transmits a communication packet including the observation data during the communication time of the own node (hereinafter referred to as other nodes). , Neighboring nodes; other nodes existing within the range where the node's outgoing radio waves reach. Also, the neighboring node that has received the communication packet wirelessly transmits the communication packet including the received observation data and the observation data of the own node during the communication time of the own node. This transfer is repeated, and observation data finally reaches the sink node S.

  The sink node S is a node as a final destination of the sensor data of each sensor node A. The function of the sink node S basically has the configuration of each sensor node A described below. As will be described later, the timing control signal transmission period (that is, time slot allocation) in each sensor node A will be described later. The time slot allocation cycle is given to each sensor node A. In addition, the sink node S may be connected (wired connection or wireless connection) or mounted with a processing device (for example, a server) that performs predetermined processing.

(A-1-2) Sensor node A Each sensor node A periodically transmits and receives timing control signals to and from neighboring nodes, and performs mutual adjustment of communication timings of its own and other timing control signals. The time slot which is the transmission period of the data signal of the own node is autonomously assigned.

  Each sensor node A transmits and receives a timing control signal to which predetermined control information is added. Although details of this control information will be described later, each sensor node A also receives control information in a state in which only the timing control signal is transmitted / received before starting transmission / reception of the data signal (that is, in the communication timing adjustment process). The timing control signal to which the control signal is added is transmitted and received.

  Further, each sensor node A detects the control information added to the reception timing control signal, and re-adjusts the communication timing based on this control information.

  FIG. 1 is a block diagram illustrating an internal configuration of the sensor node A according to the first embodiment. In FIG. 1, the sensor node A of the first embodiment includes at least a communication timing calculation unit 1, a timing control signal reception unit 2, a timing control signal transmission unit 3, a tuning determination unit 4, a data communication unit 5, and a sensor 6. It is configured.

  The timing control signal receiving means 2 receives a timing control signal sent from a neighboring node, and gives the received timing control signal to the communication timing calculation means 1 and the tuning determination means 4.

  The timing control signal receiving means 2 detects control information added to the received timing control signal, and supplies the detected control information to the communication timing calculating means 1 and the timing control signal transmitting means 3. .

  Here, the control information added to the timing control signal corresponds to “time slot allocation cycle information (cycle information)”, “data size information of data signal”, “destination node number”, and the like.

  The “time slot allocation cycle information” is information relating to the time slot allocation cycle determined or updated by the sink node S.

  “Data size information of data signal” is information relating to the data size of the data signal to be transmitted by the own node or the number of corresponding packets in the time slot allocation period. This “data size information of the data signal” does not mean the data size of each data signal that is actually transmitted in the period, but is an estimate of the traffic generated in the own node after the start of data communication (that is, it should be transmitted) This is information indicating the sum of the data sizes of all data signals.

  The “destination node number” is information regarding a destination node number for designating a counterpart node to which the own node directly transmits a data signal, and indicates a destination node number for each data signal.

  The communication timing calculation means 1 calculates the communication timing of the data signal of the own node using the timing control signal received from the timing control signal receiving means 2 and the transmission timing of the control signal of the own node.

  As a communication timing calculation method in the communication timing calculation means 1, the mechanism described in Patent Literature 1 to Patent Literature 7, etc. is used so that the transmission timing of the timing control signal does not collide with neighboring nodes. On the other hand, the transmission timing of the timing control signal of the own node is controlled based on the communication timing relationship between the own node and the neighboring nodes, and the communication timing pattern is formed in an autonomous and distributed manner. Note that the communication timing pattern may be equal, or may be unequal according to traffic.

  Further, the communication timing calculation means 1 receives the control information added to the reception timing control signal from the timing control signal reception means 2, and uses the time slot allocation period included in the control information to re-set the communication timing. Make adjustments.

  Thereby, each sensor node A can readjust the communication timing using an appropriate time slot allocation period determined by the sink node S where the traffic in the network is concentrated.

  Further, the communication timing calculation unit 1 forms a phase signal that defines the communication timing in the own node, and provides the phase signal (phase information) to the timing control signal transmission unit 3, the tuning determination unit 4, and the data communication unit 5. Is.

  The timing control signal transmission unit 3 receives phase information from the communication timing calculation unit 1 and transmits an output timing control signal. At this time, the timing control signal transmission means 3 adds control information to the output timing control signal.

  In other words, the timing control signal transmission unit 3 changes the “transmission destination node number” and the “data size information of the data signal” in the control information.

  Here, as a method of changing the content of the “data size information of the data signal”, various methods can be applied as long as the total number of transmission data sizes related to traffic in the own node can be obtained. Such a method can be applied.

  First, the timing control signal transmission means 3 refers to “data size information of a data signal” and “transmission destination node number” which are control information added to a timing control signal received from another node in one cycle. It is determined whether or not there is a transmission destination node number corresponding to the number of the own node (step S1).

  If there is one whose “destination node number” corresponds to its own node number, the timing control signal transmission means 3 calculates the sum of “data size information of the data signal” (step S2).

  If there is no “destination node number” corresponding to the number of the own node, the timing control signal transmission unit 3 sets “data size information of the data signal” to 0 (step S3).

  Next, when there is observation data sensed by the sensor 6 in one cycle, the timing control signal transmission means 3 calculates the data size of the data signal when the observation data is converted into a data signal, and the data signal The data size is added to “data size information of data signal” in steps S2 and S3 (step S4).

  For example, assuming that the data signal is generally composed of a plurality of packets and the data size of each packet is assumed to be uniform, the data size can be handled simply as the number of packets. Therefore, for the sake of simplicity, “data size information of data signal” will be described as “data signal packet number information”.

  For example, if a data signal is generally composed of a plurality of packets and the data size of each packet is assumed to be uniform, the data size can be handled simply as the number of packets. Therefore, in the following, for the sake of simplicity, “data size of data signal” is described as “number of data signal packets”.

  Further, it is assumed that the sensing cycle in each sensor node is the same as the “time slot allocation cycle”, and sensing is performed once per cycle. Furthermore, it is assumed that the observation data obtained by one sensing is converted into a data signal of one packet having a fixed data size uniformly for all nodes.

  For example, when the sensor node A at the end transmits one packet of the data signal for the observation data of the own node in one cycle unit, the transmission source sensor node of the packet receives the received one packet and the data signal for the observation data of the own node. One packet (two packets in total) is transmitted every cycle. Therefore, when a data signal is transmitted from a terminal sensor node to a sink node via a multi-stage relay sensor node, the number of data signal packets to be transmitted in one cycle, that is, the data size is generally closer to the sensor node. Will increase.

  The tuning determination means 4 determines whether the mutual adjustment of the output timing control signal transmission timing performed between the own node or one or a plurality of neighboring nodes is in a “transient state” or a “steady state”. To do. As this determination method, for example, when the generation timings of the input timing control signal and the output timing control signal are observed, and the time difference between the generation timings of a plurality of nodes that exchange timing control signals is stable in time. It determines with it being "steady state", and when that is not right, it determines with "excessive state." In the case of this embodiment, the tuning determination unit 4 receives from the communication timing calculation unit 1 as a signal for capturing the generation timing of the output timing control signal from the own node, instead of the output timing control signal. Phase information (phase signal) is input.

  Further, the tuning determination means 4 provides the data communication means 5 with a tuning determination signal indicating a determination result for each period of the phase signal and a slot signal indicating the minimum value of the phase signal at the generation timing of the input timing control signal. give.

  The sensor 6 is for observing physical or chemical environmental information such as intensity of sound or vibration, chemical substance concentration, temperature, and the like, and provides observation data to the data communication means.

  The data communication means 5 transmits observation data and / or input data signals (including both cases) as an output data signal to other nodes. When the tuning determination signal indicates “steady state”, the data communication means 15 uses a time slot (which is not a fixed time interval assigned by the system or the like, but uses the term “time slot”). When the tuning determination signal indicates “transient state”, the transmission operation is stopped. The output data signal may be a transmission frequency in the same frequency band as the output timing control signal.

  As for the time slot, the start point of the time slot is the timing at which the transmission of the output timing control signal is completed, and the end point of the time slot is slightly different from the timing of the first input timing control signal for each period of the phase signal. The previous timing is set by the offset.

(A-1-3) About Sink Node S The sink node S receives a data signal from each sensor node A that is multi-hopped through neighboring nodes. The sink node S is connected to an information processing apparatus such as a server, for example, and gives the acquired data signal to the information processing apparatus to perform predetermined processing.

  The sink node S transmits and receives a timing control signal to which predetermined control information is added to and from the sensor node S in the second vicinity range centered on the own node. In addition, the sink node S determines and updates the time slot allocation period according to traffic based on the control information added to the timing control signal, and adds the determined and updated time slot allocation period as control information. A control signal is transmitted.

  It should be noted that a common initial value is set as the cycle (initial value of the cycle) at the operation start time in the sink node S and all the sensor nodes A. For example, only timing control signals can be transmitted and received between the nodes. About the size is set.

  FIG. 3 is a block diagram illustrating an internal configuration of the sink node S according to the first embodiment. In FIG. 3, the sync node S of the first embodiment includes at least a communication timing calculation unit 11, a timing control signal reception unit 12, a timing control signal transmission unit 13, a period determination unit 14, and a sync data communication unit 15. Configured.

  The communication timing calculation means 11, the timing control signal reception means 12 and the timing control signal transmission means 13 have the same functions as the communication timing calculation means 1, the timing control signal reception means 2 and the timing control signal transmission means 3 of each sensor node A. To do. Therefore, detailed description here is omitted.

  Note that the sink node S does not need to transmit a data signal to the sensor node A, and there is no problem as long as it can acquire a time slot having a size capable of transmitting a timing control signal. Therefore, the communication timing calculation unit 11 can apply the communication timing calculation process in consideration of this point. For example, the communication timing calculation unit 11 determines the phase width corresponding to the time slot necessary for the sync node S to transmit the timing control signal, sets the phase response function so as to ensure the phase width, and performs communication. A method for calculating timing can be applied.

  The sink data communication unit 15 collects data signals received from the sensor node A existing in the first neighboring node range at regular intervals and outputs them to an information processing apparatus such as a server. Here, an information processing device such as a server means a device that processes and manages all observation data collected on the network.

  Note that the sync data communication unit 15 may execute the output operation of the sync data signal independently of the reception of the data signal from the sensor node A. In other words, the sync data communication unit 15 may output the sync data signal while receiving the data signal.

  The period determining unit 14 receives control information added to the reception timing control signal from the timing control signal receiving unit 12, and based on the control information, determines a time slot allocation period (hereinafter referred to as an update period) according to traffic. To decide. The cycle determination unit 14 gives the determined update cycle to the communication timing calculation unit 11 and the timing control signal transmission unit 13.

  When data signals are not transmitted / received during the communication timing adjustment process, the initial value of the time slot allocation period may be set to a size that allows only transmission / reception of timing control signals between nodes, and a relatively small value may be used. it can. This is because the smaller the initial period value, the smaller the time required to determine the update period.

  Below, the example of the update period determination method by the period determination means 14 is demonstrated. As described above, the sink node S transmits and receives a timing control signal to and from the sensor node S in the second vicinity range centered on the own node.

  The period determining means 14 determines an update period using the following equation based on the control information added to the received timing control signal. However, this update cycle determination process is executed only when the following conditions are satisfied.

  When the sink node S and the sensor node A start to operate, the value of the control information “data size information of data signal” generally increases with time, and eventually reaches a steady state that takes a stable value. The update period determining process by the period determining unit 14 is executed only when it is detected that the value of the control information in the “data size information of the data signal” is in a steady state.

Here, the cycle determination means 14 is in a steady state when the value of the control information of “data size information of the data signal” added to the reception timing control signal has not changed for a certain period. judge. This constant time value can be determined experimentally.

here,
T _update : Update cycle α: Constant parameter W _data : Time required to transmit one packet of data signal W _pulse : Time required to transmit timing control signal Here, for simplicity, the timing control signal is also treated as one packet. S _pace : Time required until the next packet transmission after packet transmission, that is, packet transmission interval N _int : Total number of sensor nodes within the second neighborhood range of the sink node P (node_num): Second neighborhood of the sink node The number of data signal packets that each sensor node within the range should transmit in the cycle. Here, node_num represents the node number of the sensor node, and P (node_num) represents the number of packets for the sensor node of the node number node_num. To express.

  In the formula (1.1), the symbol • represents a product. The value of α is a constant parameter that is experimentally determined in advance. By appropriately setting the value of α, it is possible to estimate the period suitable for the node arrangement form and the arrangement environment.

  As described above, when the update cycle determination process is executed according to the equation (1.1), the cycle determination unit 14 gives the value to the timing control signal transmission unit 13 as update cycle information, and controls this update cycle information. It is added to the timing control signal as “period information” of information and transmitted. In addition, after the timing control signal is transmitted, the cycle determination unit 14 gives the update cycle information to the communication timing calculation unit 11 to update the time slot allocation cycle.

  Further, the sensor node A that has received the timing signal added with “period information (period update information)” transmitted from the sink node S adds the control information to the timing control signal and transmits it. In the sensor node A, after transmitting the timing control signal, the communication timing calculation means 1 updates the time slot allocation period based on the “period information” and calculates the communication timing.

  As each sensor node A sequentially executes such an operation, “period information (period update information)” is given to all nodes in the network NT, and each node uses the update period to determine the communication timing. Perform readjustment.

(A-2) Effect of First Embodiment As described above, according to the first embodiment, time slot allocation is performed in an autonomous and distributed manner by mutually transmitting and receiving timing control signals between a plurality of nodes. In the data communication to be adjusted, by using a timing control signal to which control information is added, an appropriate time slot allocation period is determined at a sink node where all traffic generated in the network is concentrated, and all nodes in the network Based on this, an operation for readjusting the communication timing can be executed.

  As a result, even if a change such as expansion or contraction of the network occurs, it is possible to autonomously change to a mode in which communication delay is minimized and operation is performed without causing congestion. Therefore, the designer is freed from the work of changing the parameter setting on site, and the scalability is improved.

(B) Other Embodiments In the first embodiment described above, a sensor network in which each node transmits sensor data is illustrated as an example of a wireless communication network. However, the present invention is not limited to a sensor network, and can be widely applied to any wireless communication network that realizes wireless communication by forming communication timing between nodes in an autonomous and distributed manner.

  In the first embodiment described above, the case where the period information, the data size information of the data signal, and the transmission destination node number are added to the timing control signal as a control signal has been described. Note that the control information to be added to the timing control signal may be any of the period information, the data size information of the data signal, and the destination node number.

  In the first embodiment, the method described in Patent Literature 1 to Patent Literature 7 is applied to the method for calculating the communication timing of the own node by the communication timing calculation means. However, other methods can be widely applied as long as the transmission timings of their own and other timing control signals are mutually adjusted and calculated according to the time evolution rule.

  The above embodiment has been described assuming a system in which a large number of nodes distributed in a space exchange data with each other wirelessly. However, the utilization form of the present invention is not limited to a system that performs wireless communication. The present invention can also be applied to a system in which a large number of nodes distributed in a space exchange data with each other by wire. For example, the present invention can be applied to a LAN system connected by wire such as Ethernet (registered trademark). Similarly, the present invention can be applied to a network in which different types of nodes are mixed, such as wired sensors or actuators or servers. Of course, the present invention can be applied to a network in which nodes connected by wire and nodes connected wirelessly are mixed.

  The function realized by the communication timing calculation unit in the above-described embodiment is assumed to be a software process realized by executing a processing program with hardware resources. It may be realized by hardware.

It is a block diagram which shows the internal structure of the sensor node of 1st Embodiment. 1 is an overall configuration diagram of a wireless sensor network according to a first embodiment. It is a block diagram which shows the internal structure of the sink node of 1st Embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1,11 ... Communication timing calculation means 2, 12 ... Timing control signal receiving means 3, 13, ... Timing control signal transmission means, A ... Sensor node, S ... Sink node, NT ... Wireless communication network.

Claims (6)

Each of the plurality of nodes constituting the communication system has a predetermined operation cycle based on mutual adjustment of the transmission timing of the timing control signal received from one or a plurality of other nodes and the transmission timing of the timing control signal of the own node. own node comprises a communication timing calculating means for calculating a time slot for transmitting a data signal in,
A first node that determines the operation cycle among the plurality of nodes is:
Period determining means for determining update period information of the operation period by a predetermined method based on data amount information of transmission data included in the timing control signal received from one or more other nodes;
Timing control signal transmitting means for including update period information of the operation period determined by the period determining means in the timing control signal and transmitting the timing control signal to one or more other nodes ;
One or more second nodes other than the first node are:
The communication timing calculation means updates the operation cycle using the update cycle information of the operation cycle included in the timing control signal received from the first node, and the own node in the updated operation cycle A communication timing control system characterized by calculating a time slot of a data signal . The period determining means receives from one or more other nodes having communication timing in the period period of the operation period when the data amount information of the transmission data addressed to the first node does not change for a certain period of time. The communication timing control system according to claim 1, wherein the update cycle information of the operation cycle is determined in accordance with total data amount information of data to be processed. The communication timing control system according to claim 1 or 2, wherein the first node is a sink node that is a final destination of transmission data transmitted by each of the nodes. Each of the plurality of nodes constituting the communication system has a predetermined operation cycle based on mutual adjustment of the transmission timing of the timing control signal received from one or a plurality of other nodes and the transmission timing of the timing control signal of the own node. A communication timing calculating means for calculating a time slot in which the node transmits a data signal,
The first node that determines the operation cycle among the plurality of nodes is:
A cycle determining step in which the cycle determining means determines the update cycle information of the operation cycle by a predetermined method based on data amount information of transmission data included in the timing control signal received from one or more other nodes;
A timing control signal transmitting step in which the timing control signal transmitting means includes the update period information of the operation period determined by the period determining means in a timing control signal and transmits the timing control signal to one or more other nodes;
Have
One or more second nodes other than the first node are:
The communication timing calculation means updates the operation cycle using the update cycle information of the operation cycle included in the timing control signal received from the first node, and the data signal of the own node in the updated operation cycle A step of calculating a time slot
A communication timing control method characterized by the above. The period determining means receives from one or more other nodes having communication timing in the period period of the operation period when the data amount information of the transmission data addressed to the first node does not change for a certain period of time. 5. The communication timing control method according to claim 4, wherein update period information of the operation period is determined according to total data amount information of data to be performed. The communication timing control method according to claim 4 or 6, wherein the first node is a sink node that is a final destination of transmission data transmitted by each of the nodes.

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