JP4229151B2 - Communication control apparatus and method, and node - Google Patents

Description

  The present invention relates to a communication control apparatus and method, and a node, for example, distributed in a space such as a system composed of a plurality of devices connected to a sensor network, an ad hoc network, or a LAN (Local Area Network). In addition, when a large number of nodes or nodes installed in a mobile body perform data communication with each other, the present invention can be applied to a method for avoiding communication data collision due to radio wave interference or the like.

  In Patent Documents 1 to 7, for example, in a system composed of a plurality of devices such as a sensor network, an ad hoc network, and a LAN, a large number of nodes distributed in a space and nodes installed in a moving body are mutually connected. In the data communication, a technology relating to a communication control apparatus and a communication control method for avoiding a collision of communication data due to radio wave interference or the like by assigning time slots autonomously and distributedly is described.

  In the communication control devices and methods described in Patent Documents 1 to 7, each node periodically communicates with neighboring nodes by transmitting and receiving impulse signals (control signals indicating the transmission timing of data of the own node). Perform mutual adjustment of timing. This realizes time slot allocation that divides one period (impulse signal transmission period) almost evenly between nodes in the impulse signal reachable range (hereinafter referred to as the interaction range).

  Patent Document 8 describes a technique for reducing power consumption of a node when using the communication control apparatuses and methods described in Patent Documents 1 to 7. In the method described in Patent Document 8, a time interval other than the time slot for transmitting and receiving a data signal is identified during the above-described period, and the data communication unit is put into a dormant state (power is turned off). As a result, it is possible to avoid wasteful consumption of power due to the data communication means being in a reception waiting state in spite of the time interval in which no data signal is received.

JP 2005-94663 A JP 2006-74617 A JP 2006-74619 A JP 2006-157438 A JP 2006-157441 A Japanese Patent Application Laid-Open No. 2006-211585 Japanese Patent Laid-Open No. 2006-211564 JP 2005-347951 A

  The technique described in Patent Document 8 described above is effective in that the power of the receiving unit of the receiving side node can be turned off without an instruction of the communication timing from the management node. There is a strong demand for energy saving.

  For example, the conventional communication control devices described in Patent Documents 1 to 8 described above perform operations related to transmission and reception of impulse signals and data signals even when there is a period in which no traffic occurs. Therefore, although the data signal is not transmitted / received, the data communication means enters the reception waiting state and the impulse signal is continuously transmitted / received.

  Therefore, there is a problem that a situation in which power is wasted is generated in the signal transmission / reception unit (corresponding to the data communication unit, the impulse signal transmission unit, and the impulse signal reception unit described in Patent Documents 1 to 7).

  In particular, in situations where traffic fluctuates irregularly in time, it is impossible to know in advance when and how long a state in which traffic has not occurred will occur. Realize.

  Therefore, the occurrence of traffic in the communication system (network) can be known in advance, the transmission / reception operation is activated according to the traffic state, and the transmission / reception operation is suspended in an unnecessary state, thereby reducing the power consumption of the signal transmission / reception unit. There is a need for a communication control apparatus and method for realizing the above, and a node having the communication control apparatus.

  In order to solve such a problem, the communication control device according to the first aspect of the present invention is mounted on a relay node that relays a data signal transmitted from a source node to a target node among a plurality of nodes constituting the communication system. (1) control signal receiving means for receiving a control signal indicating the data transmission timing of each neighboring node transmitted by one or a plurality of neighboring nodes; and (2) indicating the data transmission timing of each neighboring node. Communication timing calculation means for determining the data transmission timing of the own node according to a predetermined time development rule based on the control signal, and (3) each neighborhood based on the data transmission timing of each neighboring node and the data transmission timing of the own node Tuning determination means for determining the mutual adjustment state of the data transmission timing between the node and the own node; (4) preset Arrival cost information storage means for storing arrival cost information required to reach the data signal from the node to the target node; and (5) each neighboring node included in the control signal indicating the data transmission timing of each neighboring node. Based on the arrival cost information and the arrival cost information of the own node, traffic determination means for determining whether or not the own node is a node contributing to relay of the data signal, and (6) determination result and synchronization determination by the traffic determination means A transmission / reception sleep state determining means for determining whether or not the transmission operation and the reception operation of the data signal and the control signal of the own node are put into a sleep state based on the determination result by the means; A control signal generator that gives the determination result of the information and traffic determination means to the control signal indicating the data transmission timing of the own node When, characterized in that it comprises a control signal transmitting means for transmitting a control signal indicating a data transmission timing of the own node formed by (8) control signal forming means.

  The node according to the second aspect of the present invention is a node having the communication control apparatus according to the first aspect of the present invention.

  A communication control method according to a third aspect of the present invention is a communication control method by a communication control device mounted on a relay node that relays a data signal transmitted from a source node to a target node among a plurality of nodes constituting the communication system. (1) provided with arrival cost information storage means for storing arrival cost information required for the data signal to reach from the preset node to the target node, and (2) the control signal reception means is 1 or A control signal receiving step for receiving a control signal indicating the data transmission timing of each neighboring node transmitted by a plurality of neighboring nodes; and (3) a communication timing calculation means based on the control signal indicating the data transmission timing of each neighboring node, A communication timing calculation step for determining the data transmission timing of the own node in accordance with a predetermined time development rule; and (4) synchronization determination means. A synchronization determination step of determining a mutual adjustment state of data transmission timing between each neighboring node and the own node based on the data transmission timing of each neighboring node and the data transmission timing of the own node; and (5) a traffic determination means Whether or not the own node is a node contributing to the relay of the data signal based on the arrival cost information of each neighboring node and the arrival cost information of the own node included in the control signal indicating the data transmission timing of each neighboring node And (6) a transmission / reception suspension state determination unit, based on the determination result by the traffic determination unit and the determination result by the tuning determination unit, the transmission operation and reception of the data signal and the control signal of the own node A transmission / reception hibernation state determination step for determining whether or not to put the operation into a hibernation state, and (7) at least a control signal forming means, A control signal forming step of adding the arrival cost information of the node and the determination result of the traffic determining means to a control signal indicating the data transmission timing of the own node; and (8) the control signal transmitting means is formed by the control signal forming means. And a control signal transmission step of transmitting a control signal indicating the data transmission timing of the own node.

  According to the present invention, it is possible to know in advance the occurrence of traffic in a communication system (network), activate a transmission / reception operation in accordance with the traffic state, and pause a transmission / reception operation in an unnecessary state, thereby transmitting / receiving signals. Can save electricity.

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

  In a sensor network that collects data by transferring sensor data observed at each node to a sink node in a multi-hop manner, the first embodiment includes the communication control device of the present invention, A case where the method is applied will be described.

  The first embodiment includes a traffic determination unit and a transmission / reception unit suspension unit, which will be described later, so that each node autonomously executes suspension control of the signal transmission / reception unit depending on whether or not traffic has occurred on the network. There is a feature.

(A-1) Configuration of First Embodiment FIG. 1 is a block diagram illustrating an internal configuration of a node according to the first embodiment. As shown in FIG. 1, the node of the first embodiment includes an impulse signal receiving means 11, a communication timing calculating means 12, an impulse signal transmitting means 13, a tuning determining means 14, a data communication means 15, a sensor 16, and a traffic determining means. 17 and at least transmission / reception unit pause means 18.

  The impulse signal receiving means 11 receives an output impulse signal transmitted from a nearby node (for example, another node existing in a range where the transmitted radio wave of the node reaches) as an input impulse signal, and uses the received impulse signal as a communication timing. This is given to the calculation means 12, the tuning determination means 14 and the traffic determination means 17. Further, the impulse signal receiving means 11 receives an instruction to pause reception of the input impulse signal from the transmission / reception unit pause means 18 and pauses reception of the input impulse signal from another node for a predetermined pause period. It is.

  Here, the impulse signal is transmitted and received as a timing signal, and has an impulse shape such as a Gaussian distribution shape, for example. The received impulse signal may be a waveform-shaped input impulse signal or a signal regenerated.

  Based on the received impulse signal received by the impulse signal receiving unit 11, the communication timing calculating unit 12 forms a phase signal that defines the communication timing at the node, and the phase signal indicating the communication timing is converted into an impulse signal transmitting unit. 13, tuning determination means 14, data communication means 15, traffic determination means 17, and transmission / reception unit suspension means 18. Even when there is no received impulse signal, the communication timing calculation means 12 forms and outputs a phase signal.

Here, assuming that the phase value of the phase signal of the node i at time t is θ _i (t), the communication timing calculation unit 12 nonlinearly converts the phase signal (= θi (t)) based on the received impulse signal. It is changed by vibration rhythm.

  This change in phase signal is a result of realizing a non-linear characteristic in which neighboring nodes are opposite in phase (vibration phase is inverted) or other phase, and trying to avoid collision using that characteristic. It is. That is, an appropriate time relationship (time difference) is to be formed so that the transmission timing of the output impulse signal between neighboring nodes does not collide.

  In addition, the method of forming a phase signal by the communication timing calculation unit 12 of the first embodiment is a method using a virtual phase model, and generates a virtual phase state for neighboring nodes when receiving a received impulse signal. Then, it is assumed that a continuous interaction using a virtual phase state with respect to this neighboring node is simulated and calculated.

  Note that the technique described in Patent Document 5 can be applied to the method of forming the phase signal by the communication timing calculation means 12, and detailed description thereof is omitted here.

  The impulse signal transmission unit 13 transmits an output impulse signal based on the phase signal from the communication timing calculation unit 12. That is, the impulse signal transmission means 13 transmits the output impulse signal when the phase signal reaches a predetermined phase α (0 ≦ α <2π). 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. For example, when the steady state is established between the node i and the node j, the mutual phase signals are shifted by the phase π. Therefore, assuming that α = 0 and the entire system are unified, the node i The transmission timing of the output impulse signal from the node j and the transmission timing of the output impulse signal from the node j are shifted by π.

  Further, the impulse signal transmission unit 13 is configured to suspend transmission of the output impulse signal for a predetermined suspension period in response to an instruction from the transmission / reception unit suspension unit 18 to suspend transmission of the output impulse signal.

  The tuning determination unit 14 transmits an output impulse signal performed between the own node and one or a plurality of neighboring nodes based on the received impulse signal from the impulse signal receiving unit 11 and the phase signal from the communication timing calculation unit 12. It is determined whether the mutual adjustment of the timing is “transient state” or “steady state”. That is, the tuning determination unit 14 observes the generation timing of the received impulse signal (corresponding to the output impulse signal of another node) and the output impulse signal, and the time difference between the generation timings of a plurality of nodes that exchange the impulse signal is time. If the time difference between the generation timings of the plurality of nodes is not temporally stable, it is determined that the state is “excessive”.

  In this embodiment, a phase signal is input to the tuning determination unit 14 as a signal for capturing the generation timing of the output impulse signal from the own node instead of the output impulse signal.

  The tuning determination unit 14 performs the tuning determination by executing the following processes (a) to (d), for example.

(A) The value β of the phase signal at the generation timing of the received impulse signal is observed over one period of the phase signal. Here, as a result of the above observation, the values β of the phase signals obtained are assumed to be β ₁ , β ₂ ,..., Β _N (0 <β ₁ <β ₂ <... Β _N <2π), respectively.

(B) Based on the observed value β of the phase signal, the difference between adjacent values (phase difference) Δ1 = β ₁ , Δ2 = β ₂ −β ₁ ,..., ΔN = β _N −β _{(N -1)} is calculated.

(C) The processes (a) and (b) are performed in units of phase of the phase signal, and the amount of change (difference) γ ₁ = Δ1 (τ + 1) −Δ1 ( τ), γ ₂ = Δ2 (τ + 1) −Δ2 (τ),..., γ _N = ΔN (τ + 1) −ΔN (τ) are calculated. Here, τ indicates a certain period of the phase signal, and τ + 1 indicates the next period of the phase signal.

(D) above variation gamma is, if either less than a minute parameter (threshold) epsilon, _{i.e., γ 1 <ε, γ 2} <ε, ..., in the case of gamma _{N <epsilon,} at "steady state" Judge that there is.

Note that a steady state may be determined when the conditions of γ ₁ <ε, γ ₂ <ε,..., Γ _N <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.

The tuning determination unit 14 provides a tuning determination signal indicating a determination result to the transmission / reception unit pause unit 18 and the data communication unit 15 for each period of the phase signal. Moreover, steady-state decision unit 14, for each period of the phase signal, which is the minimum value beta ₁ of the values of the phase signal beta in the generation timing of the received impulse signal and outputs the data communication unit 15 as a slot signal.

Note that the output of the minimum value β ₁ as a slot signal is related to α = 0 as described above. Depending on the selection of the value of α, the β value applied to the slot signal may be The value changes.

  The node 10 has a function of relaying and transmitting data received from other nodes, and a data transmission function using itself as a transmission source.

  When the node performs a function of relaying and transmitting data received from another node, the data communication means 15 receives a data signal (input data signal) from the other node and transmits it as an output data signal. is there.

  In addition, when the node performs the data transmission function with its own node as the transmission source, the sensor 16 detects physical or chemical environmental information such as the intensity of sound or vibration, the concentration of the chemical substance, and the temperature. The observation data is output to the data communication means 15. And the data communication means 15 transmits the observation data from the sensor 16 to an other node as an output signal.

  When the tuning determination signal from the tuning determination unit 14 indicates “steady state” for transmission of the output data signal, the data communication unit 15 is not a time slot described later (although it is not a fixed time interval assigned by the system or the like). , The term “time slot” is used), and the transmission operation is stopped when the tuning determination signal indicates “transient state”. Note that the output data signal may have a transmission frequency in the same frequency band as the output impulse signal.

  Further, the data communication means 15 suspends transmission and reception of data signals for a predetermined pause period in response to an instruction to pause transmission and reception of data signals from the transmission / reception unit suspension means 18. .

Here, the time slot is a period in which the phase θ _i (t) of the phase signal is δ ₁ ≦ θ _i (t) ≦ β ₁ −δ ₂ . The start point of the time slot (the value of the phase signal at that time is δ ₁ ) is the timing at which the transmission of the output impulse signal is completed, and the end point of the time slot (the value of the phase signal at that time is β ₁ − (δ ₂ ) is a timing that is slightly offset by δ ₂ before the timing of the first received impulse signal for each period of the phase signal. δ ₁ and δ ₂ 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) 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. For example, δ1 and δ2 can be determined experimentally under the installation state of the node 10.

  The traffic determining means 17 determines that traffic has occurred on the network based on the received impulse signal received from the impulse signal receiving means 11 or the observation data received from the sensor 16, and according to the determination result. Thus, at least identification information for identifying “the presence or absence of traffic” is added to the impulse signal, and the impulse signal is given to the transmission / reception unit pause means 18.

  Here, when the traffic determination means 17 receives the observation data from the sensor 16, it determines that the own node 10 is a node that is a traffic generation source, and receives the reception impulse signal from the impulse signal reception means 11. It is determined that the other node is a traffic generation source.

  When the own node 10 is a traffic generation source (that is, functions as a source of sensor data), the traffic determining means 17 becomes identification information indicating that “there is traffic” since it becomes the source, and the own node X to the sink node The information indicating the number of hops Nhop (X) up to is added to the impulse signal.

  Here, in each node, the “cost required to reach the data signal from the own node to the target node” is preset in the cost storage means 17a. In the first embodiment, this “from the own node to the target node” is set. The “cost required to reach the data signal to the node” will be described as the number of hops Nhop (X) from the own node to the sink node.

  Various methods can be applied as a method for setting the number of hops Nhop (X) from the own node to the sink node. For example, the sink node is an impulse signal or a signal equivalent to an impulse signal (referred to as an impulse signal or the like). And impulse signals and the like are transferred between nodes in a multi-hop manner. Then, each node counts the number of transfers, observes the number of hops until it reaches each node, and determines the number of hops from its own node to the sink node that is the minimum number of hops observed at each node. Set as (X).

  Further, when the other node is a traffic transmission source, the traffic determination unit 17 includes the identification information of “the presence / absence of traffic” added to the received impulse signal from the impulse signal reception unit 11 and the source node X to the sink node. Based on the information indicating the number of hops Nhop (X) up to, the presence / absence of traffic in the own node is determined (that is, whether the own node is a node that needs to transfer a data signal). At the same time, the presence or absence of traffic to be added to the impulse signal output as the output impulse signal is determined.

  Details of a method for determining the presence / absence of traffic in the own node and the presence / absence of traffic added to the impulse signal by the traffic determination means 17 will be described later.

  The traffic determining means 17 determines that the transmission period of the output impulse signal based on the phase signal received from the communication timing calculating means 12 is one period, and makes a determination based on the received impulse signal received within the period of this one period. To do.

  The transmission / reception unit suspension unit 18 receives the determination result of “the presence / absence of traffic in its own node” from the traffic determination unit 17 and also receives the tuning determination signal from the tuning determination unit 14 and determines the determination result of “the presence / absence of traffic in its own node”. Based on the tuning determination signal, it is determined whether or not a predetermined condition is satisfied.

  When the state satisfying the predetermined condition lasts for a predetermined period, the transmission / reception unit suspension unit 18 adds information indicating that the state transitions from the active state to the suspension state to the impulse signal and provides the impulse signal transmission unit 13 with the information. .

  Further, the transmission / reception unit pause means 18 sends an instruction to pause the transmission and reception of the impulse signal and the data signal after transmission of the impulse signal from the impulse signal transmission means 13, the impulse signal reception means 11, the impulse signal transmission means 13, and This is performed for the data communication means 12.

(A-2) Operation of First Embodiment Next, the operation of the communication control process in the node according to the first embodiment will be described in detail with reference to the drawings.

  FIG. 2 is a configuration diagram showing an overall image of a sensor network configured by a set of nodes arranged in a space. In FIG. 2, each round point represents a node (sensor node), and a dotted circle surrounding the node represents an arrival range (that is, an interaction range) of an impulse signal transmitted from a node located at the center of the circle. In FIG. 2, node A is a data signal source node, which transmits a data signal toward sink node S, and node B is a node that transfers a data signal from node A.

  In the following description, for convenience of explanation, it is assumed that there is no node other than the node A as a traffic generation source node.

  First, the operation of the node A, which is a data signal source and a traffic generation source, will be described with reference to FIGS.

  In the node A, when the sensor 16 of the node A observes the environmental information, a phase signal that defines a communication timing for transmitting a data signal including the observed data is formed, and an output impulse signal based on the phase signal is output. The

  At this time, in the node A, as shown in FIGS. 1 and 3, the observation data is given to the traffic determination means 17 of the node A from the sensor 16 of the node A that observed the environmental information (S11).

  When the observation data is given to the traffic determination means 17 of the node A, the traffic determination means 17 identifies the identification information indicating “there is traffic” as the traffic identification information and the number of hops Hhop from the own node A to the sink node S ( A) is added to the impulse signal transmitted by the node A (S12), and the impulse signal is given to the transmission / reception unit pause means 18.

  The transmission / reception unit pause unit 18 adds the identification information indicating “with traffic” to the impulse signal, so that the transmission and reception operations of the data signal and the impulse signal are activated, and the impulse signal received from the traffic determination unit 17 Is supplied to the impulse signal transmitting means 13 and output as an output impulse signal.

  Here, the node A which is a traffic generation source continuously adds and outputs identification information indicating “there is traffic” to each impulse signal for a period during which the generation of the traffic continues, but the generation of the traffic stops. Alternatively, when the processing is completed, identification information indicating “no traffic” is added to each impulse signal and output.

  Next, the operation of the node B that has received the output impulse signal output from the node A, which is a traffic generation source, will be described with reference to FIG. 1, FIG. 4, and FIG.

  The node B receives the impulse signal output from all the other nodes existing within the interaction range of the own node. Further, the node B determines the presence / absence of traffic in the node B and the output impulse based on the information added to all the impulse signals received during the period in which the transmission period of the impulse signal transmitted by the node is one cycle. The presence or absence of traffic to be added to the signal is determined.

  In the following, for convenience of explanation, it is assumed that the node B receives an impulse signal to which identification information indicating “no traffic” is added from other nodes other than the node A.

  First, when the impulse signal output from the other node is received by the impulse signal receiving means at the node B, the received impulse signal is given to the traffic determining means 17 (S21).

  When the received impulse signal is given to the traffic determining means 17, the traffic determining means 17 extracts the traffic identification information added to the received impulse signal (S22), and the traffic identification information indicates “with traffic”. It is determined whether it is identification information (S23).

  At this time, when the identification information indicates “with traffic”, the traffic determination unit 17 extracts “the number of hops Nhop (A) from the source node A to the sink node S” added to the received impulse signal. (S24) The “hop count Nhop (A) from the source node A to the sink node S” is compared with the “hop count Nhop (B) from the own node B to the sink node S” (S25).

  When “Nhop (B) ≦ Nhop (A)”, the traffic determining unit 17 determines that the node B is a node that needs to transfer the data signal from the node A, The presence / absence of traffic is determined to be “with traffic” (S26).

  On the other hand, when “Nhop (B)> Nhop (A)”, the traffic determination unit 17 determines that the node B is a node that does not need to transfer the data signal from the node A, The presence / absence of traffic is determined to be “no traffic” (S26).

  In S23, when all received received impulse signals are added with identification information indicating "no traffic", the traffic determining means 17 does not require the node B to transfer the data signal from the node A. It is determined that the node is a node, and “the presence / absence of traffic in the own node” is determined as “no traffic” (S26).

  As described above, the process related to the determination of “presence / absence of traffic in the own node” shown in S26 is performed on the information added to the received impulse signal received within the period in which the transmission period of the impulse signal of the node B is one period. Based on.

  For example, when a plurality of received impulse signals to which identification information indicating “with traffic” is added are received (that is, identification information indicating “with traffic” is added from other nodes than node A). When an impulse signal is received), “the presence / absence of traffic in the own node” is determined as follows.

  In this case, an impulse signal satisfying “Nhop (B) ≦ Nhop (A)” at least one of a plurality of impulse signals to which identification information indicating “with traffic” is added within one period. When there is a traffic, the traffic determining means 17 determines that the own node B is a node that needs to transfer the data signal from the node A, and determines “the presence / absence of traffic in the own node” as “with traffic”.

  On the other hand, when the impulse signals satisfying “Nhop (B)> Nhop (A)” among the plurality of impulse signals to which identification information indicating “with traffic” is received within one period, The determining unit 17 determines that the own node B is a node that does not need to transfer the data signal from the node A, and determines that “the presence / absence of traffic in the own node” is “no traffic”.

  When the determination of “the presence / absence of traffic in its own node B” is made in S26, the traffic determination means 17 determines “the distinction of the traffic identification information added to the impulse signal” output by the node B (S27). .

  At this time, any one of the impulse signals added with the identification information indicating “with traffic” received within one period satisfies “Nhop (B) <Nhop (A)”. In this case, the traffic determining unit 17 determines identification information indicating “with traffic” as “traffic identification information to be added to the impulse signal”.

  On the other hand, when all of the impulse signals to which the identification information indicating “with traffic” is received within one period are all satisfying “Nhop (B) ≧ Nhop (A)”, the traffic determining means 17 determines identification information indicating “no traffic” as “traffic identification information to be added to the impulse signal”.

  Here, when "Nhop (B) = Nhop (A)" is determined when "the presence / absence of traffic in the own node" is determined and when "different traffic identification information added to the impulse signal" is determined. Please note that is different.

  The reason for providing such a difference is that information on “with traffic” is transferred one after another between nodes having the same “cost required to reach the signal from the local node to the target node”, and the influence is caused by the source of traffic. This is to prevent a node existing in a spatial region other than between the node A and the sink node S (target node). That is, only nodes located in a spatially appropriate range maintain an active state, and other nodes are configured to be in a dormant state.

  In this way, the traffic determining means 17 of the node B adds the “identification information indicating the presence / absence of traffic” and the “hop count Nhop (B) from the own node to the sink node” to the impulse signal for transmission.

  The node Y that has received the impulse signal to which the identification information indicating “with traffic” is added from the node B performs the same operation as the node B, and the subsequent nodes also perform the same operation one after another. Between the node A and the sink node S of the traffic generation source, a cluster of nodes whose determination result of “the presence / absence of traffic” is “with traffic” is formed.

  Next, the operation of the transmission / reception suspension unit 18 of a certain node will be described in detail with reference to FIGS.

  Based on the tuning determination signal from the tuning determination unit 14 and the determination result of “the presence / absence of traffic in the own node” by the traffic determination unit 17, the transmission / reception unit suspension unit 18 of a certain node transmits the data signal and the impulse signal at the node. And determining whether the reception operation is to be activated or to be in a dormant state.

  At this time, first, the transmission / reception unit pause unit 18 determines whether or not both of the following conditions A and B are satisfied, and the state that satisfies both the conditions A and B continues for the Mntr period. It is judged (S31-S33).

  (Condition A) The determination result of the tuning determination means 14 is “steady state”. That is, the mutual adjustment of the transmission timing has converged (S32).

  (Condition B) The determination result of “the presence / absence of traffic in the own node” by the traffic determination means 17 is “no traffic” (S33).

  When the state satisfying both the condition A and the condition B continues for the Mntr period, the transmission / reception unit pause unit 18 adds information indicating transition to the pause state to the impulse signal and transmits it (S34).

  In addition, after transmitting an impulse signal to which information indicating a transition to the dormant state is transmitted, the transmission / reception unit pause unit 18 receives the impulse signal so as to stop transmission and reception of the impulse signal and the data signal during the Mslp period. Instruction is given to the means 11, the impulse signal transmitting means 13 and the data communication means 15 (S35).

  Then, during this Mslp period, the impulse signal receiving means 11 and the impulse signal transmitting means 13 pause the transmission and reception of the impulse signal, and the data communication means 15 pauses the transmission and reception of the data signal.

  However, when a plurality of impulse signals to which information indicating transition to a dormant state from other nodes is added are generally received within the above Mntr period, the Mslp period elapses starting from the earliest reception timing. It will return to activity later. The above Mntr and Mslp are constant parameters, and their values can be determined experimentally.

  In this way, when the node that has transitioned to the dormant state returns from the dormant state to the active state again, the node again starts to determine whether or not the above conditions A and B are satisfied. Perform the action.

  Here, the communication timing calculation means 12 of the first embodiment forms a phase signal by a method using a virtual phase model, and applies the communication timing calculation means described in Patent Document 5. . The virtual phase model calculated by the communication timing calculation means 12 takes a form that disappears when operating in the W cycle (W is a constant parameter).

  The setting of the value of the constant parameter W will be described. For example, even if the node is active, if there is another node that is in a dormant state, the node does not receive an impulse signal for the Mslp period from the node in the dormant state. Further, for example, when the own node is in a dormant state, the reception of the impulse signal of the own node is also stopped, so that it is impossible to receive all the impulse signals from other nodes.

  Therefore, the constant parameter W in the communication timing calculation unit 12 needs to be a value satisfying at least “W> Mslp”.

  However, in practice, the constant parameter W is generally set to “because a state in which the impulse signal of another node cannot be received for a longer period than the Mslp period, such as when the own node transitions from an active state to a dormant state. It is desirable that the value satisfies “W> K × Mslp”. Here, K represents a constant. The specific value of the constant parameter W is determined experimentally.

  As described above, each node constituting the sensor network executes the above-described operation, so that in the node set shown in FIG. 2, the node that is active for the transmission and reception operations of the data signal and the impulse signal is suspended. It is possible to form a state in which nodes to be in a state are divided by partial regions.

  That is, between the traffic generation source node A and the sink node S, a cluster of nodes whose determination result of “the presence / absence of traffic” is “with traffic” is formed. As long as A continues to generate traffic, it will remain active.

  On the other hand, if there is no node that generates traffic other than node A, the nodes other than this partial area temporarily enter a dormant state and return to the active state after the Mslp period. Thereafter, the same operation is repeated.

  As described above, in response to the situation where traffic is localized temporally and spatially, the nodes in the partial area where data signals are transferred become active only for the necessary time. A mode of entering a dormant state is realized.

  In the first embodiment, since the mutual adjustment of the communication timing between the nodes within the interaction range is achieved, the transition from the active state to the dormant state is performed, and then the communication timing is changed when returning to the active state. It has a feature that data communication without collision can be performed only by fine adjustment. This fine adjustment of the communication timing is achieved by transmitting and receiving impulse signals between nodes. Therefore, when the occurrence of traffic is confirmed when returning to the active state, data can be transferred to the sink node with a relatively low delay.

  In addition, as long as traffic continues to occur, the nodes in the related partial areas remain active, and when the generation of traffic stops for a certain period of time, the node enters a dormant state, which corresponds to a situation in which traffic occurs irregularly in time. Thus, it is possible to reduce the power consumption of the node.

(A-3) Effects of First Embodiment As described above, according to the first embodiment, mutual adjustment of time slot allocation is performed autonomously and distributedly by a plurality of nodes transmitting and receiving impulse signals. In the communication method, by newly adding traffic determining means and transmission / reception unit suspension means, each node autonomously executes suspension control of the signal transmission / reception unit depending on whether or not traffic has occurred on the network. Can do.

  As a result, nodes in the partial area where data signals need to be transferred become active for the required time in a manner corresponding to the situation where traffic generation in the network is localized in time and space. Other than that, the form which becomes a dormant state is realized. Therefore, according to the first embodiment, it is possible to reduce the power consumption of the node in response to a situation where traffic occurs irregularly in time.

(B) Other Embodiments (B-1) In the present invention, it should be noted that the implementation form of the impulse signal transmitted / received between the nodes is not particularly limited as long as a specific timing can be transmitted. . An example of the simplest implementation of an impulse signal is a single pulse having a function shape such as a Gaussian distribution or a rectangle. However, the impulse signal does not necessarily have to be a single pulse, and a form in which an impulse signal having one meaning is formed using a plurality of pulses may be used. For example, a pulse train corresponding to a specific bit pattern is handled as one impulse signal. Such a form is effective when it is difficult to identify a signal with a single pulse in an environment where a lot of noise exists. The meaning of the impulse signal described in the embodiment of the present invention conceptually represents a signal indicating a specific timing, and there are various forms of its implementation.

(B-2) A signal obtained by adding a certain type of data called a node identification number to the impulse signal (a signal indicating a specific timing) may be applied as the impulse signal. It should be noted that there are various forms of realizing a signal obtained by adding certain data to a signal indicating a specific timing.

  Moreover, the communication timing calculation means 12 can apply what forms a phase signal by various systems.

(B-3) The first embodiment has been described assuming a system in which a large number of nodes distributed in space exchange data with each other wirelessly. However, the usage form of the present invention is not limited to a system that performs wireless communication. It can also be applied to a system in which a large number of nodes distributed in 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 sensors, actuators, and servers connected in a wired manner. Of course, the present invention can be applied to a network in which nodes connected by wire and nodes connected wirelessly are mixed.

  Furthermore, the present invention can be used as a communication protocol for exchanging routing tables at different timings on the Internet. Here, the router is a relay device having a function of distributing the destination of information flowing on the network (communication path selection). The routing table is a communication route selection rule that is referred to when allocating information destinations. In order to realize efficient communication, it is necessary to update the routing table sequentially according to changes on the network, local traffic changes, and the like. For this reason, a large number of routers existing on the network exchange routing tables with each other at regular time intervals. However, it is disclosed in the document “Floyd, S., and Jacobson, V.,“ The Synchronization of Periodic Routing Messages ”, IEEE / ACM Transactions on Networking, Vol.2 No.2, pp.122-136, April 1994.” As described above, it has been found that although each router transmits a routing table independently, a phenomenon occurs in which the routers gradually synchronize (collision). The literature proposes a method to deal with this problem by giving random variability to the processing cycle of each node for the communication protocol used for exchanging routing tables, and shows that a certain effect can be obtained. ing. However, since the method disclosed in the above document is basically a method that depends only on randomness, its effect is not sufficient.

  On the other hand, when the present invention is applied to the above problem, it is possible to autonomously mutually adjust the time slots for transmitting the routing table between neighboring routers. Therefore, the transmissions of the routers have different timings, and a high effect can be obtained as compared with the method disclosed in the above document.

  As described above, the present invention is applicable to the problem of collision and synchronization of outgoing data existing in any network regardless of wireless system or wired system, and is efficient data having both adaptability and stability. It can be used as a communication protocol for realizing communication.

(B-4) As for acquisition control of communication timing information (phase signal in the embodiment), it does not matter how the timing information is used for communication. For example, if the transmission frequency of the data signal from each node is different, communication may be performed without setting a time slot. Even in this case, the start of data communication can be determined from the communication timing information. It should be determined.

(B-5) The function realized by the node described in the first embodiment can be realized as software. However, if a circuit configuration that performs the same operation can be taken, the node can be used as hardware. It may be implemented.

It is a block diagram which shows the internal structure of the node of 1st Embodiment. It is an image figure which shows the structure of the sensor network of 1st Embodiment. It is a flowchart which shows operation | movement of the traffic determination means of the node of the traffic generation source of 1st Embodiment. It is a flowchart which shows operation | movement of the traffic determination means of the relay node of 1st Embodiment. It is a flowchart which shows operation | movement of the transmission / reception part pause | pause part of the node of 1st Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Node, 11 ... Impulse signal reception means, 12 ... Communication timing calculation means, 13 ... Impulse signal transmission means, 14 ... Tuning determination means, 15 ... Data communication means, 16 ... Sensor, 17 ... Traffic determination means, 18 ... Transmission / reception Club suspension means.

Claims (6)

In a communication control device mounted on a relay node that relays a data signal transmitted from a source node to a target node among a plurality of nodes constituting a communication system,
Control signal receiving means for receiving a control signal indicating data transmission timing of each neighboring node transmitted by one or more neighboring nodes;
Communication timing calculation means for determining the data transmission timing of the own node according to a predetermined time development rule based on the control signal indicating the data transmission timing of each neighboring node,
Tuning determination means for determining a mutual adjustment state of the data transmission timing between each of the neighboring nodes and the own node based on the data transmission timing of each of the neighboring nodes and the data transmission timing of the own node;
Arrival cost information storage means for storing arrival cost information required to reach a data signal from the preset node to the target node;
Whether the own node contributes to relay of the data signal based on the arrival cost information of each neighboring node included in the control signal indicating the data transmission timing of each neighboring node and the arrival cost information of the own node Traffic determination means for determining whether or not,
Based on the determination result by the traffic determination means and the determination result by the tuning determination means, a transmission / reception sleep state determination means for determining whether or not the transmission operation and the reception operation of the data signal and the control signal of the own node are to be suspended. When,
Control signal forming means for providing at least the arrival cost information of the own node and the determination result of the traffic determination means to a control signal indicating the data transmission timing of the own node;
And a control signal transmitting means for transmitting a control signal indicating the data transmission timing of the own node formed by the control signal forming means.   Among the control signals indicating the data transmission timing of each of the neighboring nodes received by the traffic determination means within the transmission period of the control signal, the arrival cost information of any neighboring node is less than or equal to the arrival cost information of the own node. In this case, it is determined that the own node is a node that contributes to the relay of the data signal. If the arrival cost information of any neighboring node is larger than the arrival cost information of the own node, the own node relays the data signal. The communication control apparatus according to claim 2, wherein the communication control apparatus determines that the node does not contribute to the node.   Among the control signals indicating the data transmission timing of each of the neighboring nodes received by the traffic determination means within the control signal transmission cycle period, the arrival cost information of any neighboring node is less than the arrival cost information of the own node. In this case, identification information indicating that there is traffic is added to the control signal indicating the data transmission timing of the own node, and when the arrival cost information of any neighboring node is equal to or higher than the arrival cost information of the own node 3. The communication control apparatus according to claim 1, wherein identification information indicating that there is no traffic is added to a control signal indicating data transmission timing of the own node.   The transmission / reception pause state determination means is such that the determination result of the tuning determination means is a steady state, and the determination result of the traffic determination means is a node whose own node does not contribute to relay of the data signal. The communication control device according to any one of claims 1 to 3, wherein when the state of being continuous is continued for a predetermined period, the communication control apparatus is put into a dormant state for a predetermined period.   A node comprising the communication control device according to claim 1. In a communication control method by a communication control device mounted on a relay node that relays a data signal transmitted from a source node to a target node among a plurality of nodes constituting a communication system,
An arrival cost information storage means for storing arrival cost information required to reach a data signal from the preset own node to the target node;
A control signal receiving step for receiving a control signal indicating a data transmission timing of each neighboring node transmitted by one or a plurality of neighboring nodes;
A communication timing calculation step in which the communication timing calculation means determines the data transmission timing of the own node according to a predetermined time development rule based on the control signal indicating the data transmission timing of each neighboring node;
Tuning determination means for determining a mutual adjustment state of the data transmission timing between each neighboring node and the own node based on the data transmission timing of each neighboring node and the data transmission timing of the own node;
The traffic determination means contributes to relaying the data signal based on the arrival cost information of each neighboring node and the arrival cost information of the own node included in the control signal indicating the data transmission timing of each neighboring node. A traffic determination step of determining whether or not the node is
Whether the transmission / reception pause state determining means sets the transmission operation and the reception operation of the data signal and the control signal of the own node based on the determination result by the traffic determination means and the determination result by the tuning determination means. A transmission / reception hibernation state determination step to determine;
A control signal forming step in which the control signal forming means gives at least the arrival cost information of the own node and the determination result of the traffic determining means to the control signal indicating the data transmission timing of the own node;
A control signal transmitting step comprising: a control signal transmitting step for transmitting a control signal indicating a data transmission timing of the own node formed by the control signal forming unit.

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