JP5435427B2 - Wireless communication apparatus, wireless communication system, and transmission timing control method - Google Patents

Description

  The present invention relates to a wireless communication system.

  In a wireless sensor network, data sensed by each node is collected by a sink node which is a data collection base station. In order for the data sensed by each node to be collected efficiently in the sink node, it is necessary for each node to communicate in an appropriate order and timing.

<Data collection>
FIG. 1 shows an example of a method for causing the sink node 5 to efficiently collect data. In FIG. 1, sensor information collected by the nodes 11, 12, 13, 21, 22, 23, and 24 is collected in the sink node 5. In FIG. 1, the number written on each node indicates the number of nodes to be relayed from the node to the sink node 5. The number of nodes to be relayed may be referred to as the hop number.

  According to the method shown in FIG. 1, the communication timing is formed so as to go from the node with the largest number of hops from the sink node 5 toward the sink node 5 in order. In other words, the communication timing of each node is constructed in an autonomously distributed manner so as to form a so-called traveling wave pattern so as to go from the node with the largest number of hops to the sink node 5 in order. As shown in the left diagram of FIG. 1, a communication timing from a node with a large number of hops toward the sink node 5 is formed. Here, the nodes 21, 22, 23, and 24 with two hops transmit sensor information. After the transmission, as shown in the right diagram of FIG. 1, a communication timing from the node with the second largest number of hops (second largest node) toward the sink node 5 is formed. Here, the nodes 11, 12, and 13 having a hop count of 1 transmit sensor information.

  In a wireless sensor network, data from each source node is spread to each node. In order for data from the source node to be efficiently diffused to each node, the source node and each node need to communicate with each other in an appropriate order and timing.

<Diffusion of data>
When data is diffused from the source node 10 which is a data collection base station to each node, processing is performed in the reverse order to the case of collecting data.

  FIG. 2 shows an example of a method for efficiently diffusing data from the source node 10 to each of the nodes 11, 12, 13, 21, 22, 23, and 24. In FIG. 2, the sensor information of the source node 10 is diffused to the nodes 11, 12, 13, 21, 22, 23, and 24. In FIG. 2, the numbers written on each node indicate the number of nodes to be relayed from the source node 10 to the node. The number of nodes to be relayed may be referred to as the hop number.

  According to the method shown in FIG. 2, the communication timing from the source node 10 is formed in order from the node having the smallest number of hops from the source node 10. In other words, the communication timing to each node is constructed in an autonomous distributed manner so as to form a so-called traveling wave pattern in order from the node having the smallest number of hops from the source node 10. As shown in the left diagram of FIG. 2, sensor information of the source node 10 is transmitted to a node with a small number of hops. Here, the source node 10 transmits sensor information to the nodes 11, 12, and 13 having a hop count of 1. After the transmission, as shown in the right diagram of FIG. 2, the node that has received the sensor information from the source node 10 transmits the sensor information to the node having the next largest number of hops. Here, the sensor information is transmitted to the nodes 21, 22, 23, and 24 having two hops.

JP 2007-28620 A Yoshiaki Taniguchi, Naoki Wakamiya, Masayuki Murata, "Implementation and Evaluation of Communication Mechanisms Using Traveling Wave Phenomena for Sensor Networks," IEICE Technical Report (NS2007-40), pp. 1-6, July 2007 . F. Hanson, J. Case, E. Buck, and J. Buck, `` Synchrony and Flash Entrainment in a New Guinea Firefly, '' Science, 174, pp. 161-164, 1971.

  In the data collection and diffusion method described above, each node holds the number of hops from the sink node or source node as a value called level. Each node builds a substantial tree structure. When collecting or diffusing data, each node transforms the phase response function in the pulse-coupled oscillator system and forms a traveling wave pattern by adjusting the timing only with the node closer to the sink node or source node than each node. To do. Data collection or diffusion is performed by forming a traveling wave pattern.

  However, the level information is propagated through the packet. Since level information is propagated through the packet, the problem of packet collision cannot be ignored. Since the problem of packet collision cannot be ignored, there is inevitably a limit to scalability.

  Further, in the sensor network, the power that can be charged by each node is limited, so that each node performs communication by switching the active mode or the sleep mode as necessary in order to reduce power consumption. However, in the data collection and diffusion method described above, each node must always be in an active state until a traveling wave pattern is formed. Since it needs to be in an active state, power consumption also increases.

  In addition, a technique has been proposed in which each node is synchronized in an autonomous and distributed manner even when each node switches between an active mode and a sleep mode by applying a pulse coupled oscillator. However, it is limited to fully synchronizing each node. It is not envisaged to collect data by forming a traveling wave pattern.

  The present invention has been made in view of the above points, and does not require a reference station for managing communication timing, and is capable of controlling communication timing in an autonomous and distributed manner, a wireless communication system, and transmission timing control. It aims to provide a method.

This wireless communication device
A wireless communication device in a wireless communication system including a plurality of wireless communication devices,
According to the phase indicated by the sawtooth wave, a transmission timing control unit that controls to transmit a pulse at a timing at which the phase reaches a maximum value;
A transmission unit for transmitting a pulse according to the timing controlled by the transmission timing control unit,
The transmission timing control unit sets the phase to zero when the phase when a pulse is received from another wireless communication device is less than a predetermined threshold, and the phase when the pulse is received from the other wireless communication device. If the phase is equal to or greater than a predetermined threshold, the phase is set to a value obtained by subtracting the phase from the maximum value after the phase reaches the maximum value.

This wireless communication system
A wireless communication system including a plurality of wireless communication devices,
The wireless communication device includes a wireless communication device that collects or spreads data and a wireless communication device other than the wireless communication device,
The other wireless communication device is:
According to the phase indicated by the sawtooth wave, a transmission timing control unit that controls to transmit a pulse at a timing at which the phase reaches a maximum value;
A transmission unit for transmitting a pulse according to the timing controlled by the transmission timing control unit,
The transmission timing control unit sets the phase to zero when the phase when a pulse is received from another wireless communication device is less than a predetermined threshold, and the phase when the pulse is received from the other wireless communication device. When the phase is equal to or greater than a predetermined threshold, after the phase reaches the maximum value, set to a value obtained by subtracting the phase from the maximum value,
The wireless communication device
According to the phase indicated by the sawtooth wave, a transmission timing control unit that controls to transmit a pulse at a timing at which the phase reaches a maximum value;
A transmission unit that transmits a pulse in accordance with the timing controlled by the transmission timing control unit.

This transmission timing control method is
A transmission timing control method in one wireless communication device in a wireless communication system including a plurality of wireless communication devices,
A transmission timing control step for controlling to transmit a pulse at a timing at which the phase reaches a maximum value according to the phase indicated by the sawtooth wave;
A transmission step of transmitting a pulse according to the timing controlled by the transmission timing control step,
The transmission timing control step sets the phase to zero when the phase when a pulse is received from another wireless communication device is less than a predetermined threshold, and the phase when the pulse is received from the other wireless communication device. If the phase is equal to or greater than a predetermined threshold, the phase is set to a value obtained by subtracting the phase from the maximum value after the phase reaches the maximum value.

  According to the disclosed wireless communication apparatus, wireless communication system, and transmission timing control method, the communication timing can be controlled in an autonomous and distributed manner without requiring a reference station for managing the communication timing.

It is explanatory drawing which shows an example of a radio | wireless communications system. It is explanatory drawing which shows an example of a radio | wireless communications system. It is explanatory drawing which shows an example of the radio | wireless communications system according to a present Example. It is a functional block diagram which shows an example of the radio | wireless communication apparatus according to a present Example. It is a partial block diagram which shows an example of the radio | wireless communication apparatus according to a present Example. It is explanatory drawing which shows an example of the transmission timing control in the radio | wireless communication apparatus according to a present Example. It is explanatory drawing which shows the example of arrangement | positioning of the radio | wireless communication apparatus in the radio | wireless communications system according to a present Example. It is explanatory drawing which shows an example of the transmission timing control in the radio | wireless communications system according to a present Example. It is explanatory drawing which shows the example of arrangement | positioning of the radio | wireless communication apparatus in the radio | wireless communications system according to a present Example. It is explanatory drawing which shows an example of the transmission timing control in the radio | wireless communications system according to a present Example. It is explanatory drawing which shows the example of mode control in the radio | wireless communication apparatus according to a present Example. It is explanatory drawing which shows the example of mode control in the radio | wireless communication apparatus according to a present Example. It is a flowchart which shows an example of operation | movement of the radio | wireless communication apparatus according to a present Example. It is a flowchart which shows an example of operation | movement of the radio | wireless communication apparatus according to a present Example. It is explanatory drawing which shows the example of arrangement | positioning of the radio | wireless communication apparatus in the radio | wireless communications system according to a present Example.

Next, the form for implementing this invention is demonstrated, referring drawings based on the following Examples.
In all the drawings for explaining the embodiments, the same reference numerals are used for those having the same function, and repeated explanation is omitted.

<System>
FIG. 3 shows a wireless communication system to which the wireless communication apparatus according to the present embodiment is applied.

The wireless communication system includes a plurality of wireless communication devices 100 _n (n is an integer where n> 0). The wireless communication device is sometimes called a node. FIG. 3 shows an example of n = 8. In FIG. 3, wireless communication devices capable of wireless communication are connected by a broken line. The wireless communication device includes a wireless sensor. Each wireless communication device controls transmission timing in an autonomous and distributed manner.

In this wireless communication system, after the control of the transmission timing is performed in accordance with the transmission timing data from the radio communication apparatus 100 ₂ -100 ₈ it is collected in the wireless communication device 100 _1. During the collection, each wireless communication device forms a traveling wave pattern.

Further, in the wireless communication system, after the control of the transmission timing is performed in accordance with the transmission timing data from the radio communication device 100 ₁ it is spread in the wireless communication apparatus 100 ₂ -100 _8. During the spreading, each wireless communication device forms a traveling wave pattern.

  The present invention has focused on experiments on fireflies in which collective blinking is observed in a traveling wave pattern in which blinking propagates like a wave. The present invention relates to the traveling wave pattern formation mechanism based on the traveling wave pattern formation condition based on the difference in natural cycle of firefly flickering obtained by the numerical simulation of the model reflecting the experimental fact. Use as a collection and diffusion method. By using the traveling wave pattern formation mechanism as a data collection / spreading method in wireless sensor networks, it is possible to realize a data collection / spreading method with more autonomous decentralization and power saving.

<Wireless communication device>
Each wireless communication device periodically transmits and receives pulses. Each wireless communication device controls the communication timing based on the interaction by the transmission and reception of the pulse. By controlling the communication timing based on the interaction due to the transmission and reception of the pulses, each wireless communication device forms a multi-hop network in an autonomous and distributed manner.

  Each wireless communication device can simultaneously receive a plurality of pulses transmitted by other wireless communication devices. For example, the plurality of pulses are received as a single pulse. Each wireless communication device receives a packet at a timing before and after transmitting a pulse.

  Further, since the power that can be charged in the wireless communication device is limited, it is possible to switch between an active mode in which communication is possible but power is consumed and a sleep mode in which communication is impossible but power consumption is low.

Since each wireless communication apparatus shown in FIG. 3 has the same configuration, only one wireless communication apparatus 100 _n included in the wireless communication system will be described.

Figure 4 shows the wireless communication apparatus 100 _n.

The wireless communication device 100 _n includes an antenna 102. The antenna 102 receives a radio signal to be transmitted by another radio communication device, and transmits the radio signal to the other radio communication device. Other wireless communication devices include a wireless communication device as a sink node that should collect data. In addition, the other wireless communication device includes a wireless communication device as a source node to which data is to be spread.

The wireless communication device 100 _n includes a transmission unit 104. Transmitter 104 is connected to antenna 102. The transmission unit 104 transmits a pulse and / or a packet to be transmitted by the wireless communication device 100 _n from the antenna 102.

The wireless communication device 100 _n includes a receiving unit 106. The receiving unit 106 is connected to the antenna 102. The receiving unit 106 receives a pulse and / or a packet to be received by the wireless communication device 100 _n from the antenna 102. The received pulse and / or packet is input to the control unit 108.

The wireless communication device 100 _n includes a control unit 108. The control unit 108 is connected to the transmission unit 104 and the reception unit 106. The control unit 108, the wireless communication apparatus 100 _n performs control of transmission timing of a packet to be transmitted. The control unit 108 controls transmission timing based on the pulse input by the receiving unit 106. In accordance with the transmission timing, control is performed so that the transmission unit 104 transmits a packet. In addition, the control unit 108 stores data necessary for transmission timing control in the storage unit 110. Further, the control unit 108 acquires sensor information detected by the sensor 112 and inputs a packet including the sensor information to the transmission unit 104.

  FIG. 5 shows the control unit 108.

  The control unit 108 includes a transmission timing control unit 1082. The transmission timing control unit 1082 is connected to the transmission unit 104, the reception unit 106, and the storage unit 110. The transmission timing control unit 1082 controls transmission timing based on the pulse input by the reception unit 106. The transmission timing control unit 1082 notifies the transmission unit 104 and the mode control unit 1086 of the transmission timing. Further, data necessary for transmission timing control is stored in the storage unit 110.

  The control unit 108 includes a transmission data generation unit 1084. The transmission data generation unit 1084 is connected to the transmission unit 104 and the sensor 112. The transmission data generation unit 1084 generates a packet including sensor information to be input by the sensor 112. The generated packet is input to the transmission unit 104. The transmission unit 104 transmits the packet by controlling the transmission timing by the transmission timing control unit 1084.

The control unit 108 includes a mode control unit 1086. The mode control unit 1086 is connected to the transmission timing control unit 1082. The mode control unit 1086 sets the mode of the wireless communication device 100 _n based on the transmission timing to be input by the transmission timing control unit 1082. For example, the active mode or the sleep mode is set.

The wireless communication device 100 _n includes a storage unit 110. The storage unit 110 is connected to the control unit 108. The storage unit 110 stores data necessary for controlling transmission timing to be input by the control unit 108.

The wireless communication device 100 _n includes a sensor 112. The sensor 112 is connected to the control unit 108. The sensor 112 includes various sensors. For example, a temperature sensor and a humidity sensor may be included. The sensor 112 inputs data obtained by sensing to the control unit 108.

<Transmission timing setting method>
The wireless communication device 100 _n periodically transmits a pulse. The wireless communication device 100 _n increases the phase at a constant speed with the passage of time. The phase may be indicated by a so-called sawtooth wave. The phase is changed when a pulse is received from another wireless communication apparatus. That is, the transmission timing is controlled based on the interaction between the phase change and the pulse.

The wireless communication device 100 _n has, as the phase φ, a timer value of a period T in which the phase increases at a constant speed (dΦ / dt) = 1 / T as time passes.

  The phase φ satisfies the formula (1).

図６は、本無線通信装置１００_ｎの有するタイマー値の位相φを示す。図６において横軸は時間（ｔ）であり、縦軸は位相φである。図６において、実線がタイマー値の位相を示す。図６によれば、以下の(a)-(c)を満たす。

FIG. 6 shows the phase φ of the timer value possessed by the wireless communication device 100 _n . In FIG. 6, the horizontal axis represents time (t), and the vertical axis represents the phase φ. In FIG. 6, the solid line indicates the phase of the timer value. According to FIG. 6, the following (a)-(c) are satisfied.

  (a) A pulse is transmitted when the phase φ reaches 1. In other words, the phase indicated by the sawtooth wave becomes the maximum value, and the phase φ becomes zero immediately after transmitting the pulse. The above operation is repeated. By repeating this operation, a pulse is periodically transmitted (FIG. 6 (a)).

  (b) If a phase φ <threshold θ when a pulse is received from another wireless communication device within the wireless communication range, the phase is reset to zero immediately after the reception (FIG. 6B). The value of the threshold θ will be described later.

  (c) If a phase φ ≧ θ is received when a pulse is received from another wireless communication device within the wireless communication range, the phase φ when the pulse is received is only internally reset. The phase when receiving the pulse is φ ′. The phase after reception of the pulse continues to increase, transmission of the next pulse is not canceled, and the pulse is transmitted. However, the phase immediately after transmitting the pulse does not become zero, but becomes the maximum value of the phase −φ ′. In other words, the phase φ does not change when the pulse is received, but after the reception, the phase φ reaches 1, and immediately after the pulse is transmitted, the phase becomes 1−φ ′ (FIG. 6C).

However, since each wireless communication device 100 _n transmits a pulse at a traveling wave timing, the wireless communication device serving as the sink node or the wireless communication device serving as the source node may receive a pulse from another wireless communication device ( b) The operation of resetting the phase φ as shown in (c) is not performed. The sink node is a wireless communication device that finally collects data from other wireless communication devices, and the source node is a wireless communication device that first spreads data to other wireless communication devices.

<Transmission timing control method when collecting data>
FIG. 7 shows an example of a transmission timing control method for collecting data. A small arrow shown in FIG. 7 indicates that a pulse is wirelessly transmitted from the wireless communication device that is the source of the arrow to the wireless communication device that is the destination of the arrow.

In Figure 7, a wireless communication device 100 ₁ is the sink node, the wireless communication device ₁₀₀ 2, · · · 100 _n is a node other than the sink node. In FIG. 7, as an example, a case where wireless communication devices 100 ₁ ,... 100 _n are arranged in a line is shown. Each wireless communication device can wirelessly communicate with an adjacent wireless communication device. In Figure 7, the wireless communication apparatus ₁₀₀ n-1, in the order of ... 100 _1, data to be transmitted by the wireless communication apparatus 100 _n is received.

The wireless communication apparatus 100 _1, when the transmission timing control is started, T ₀ is set as the period of the phase of the timer value. Also, T is set as the period of the timer value phase in the wireless communication devices 100 ₂ ,... 100 _n when transmission timing control is started. When collecting data, it is necessary to satisfy T ₀ > T, 2 ((T ₀ / T) −1) <θ ≦ 2- (T ₀ / T).

The phase T ₀ of the phase of the timer value is stored in the storage unit 110 of the wireless communication device serving as the sink node as data necessary for controlling the transmission timing. The transmission timing control unit 1082 acquires the period T ₀ stored in the storage unit 110.

  The phase T of the timer value and the threshold value θ are stored in the storage unit 110 of the wireless communication apparatus other than the sink node as data necessary for transmission timing control. The transmission timing control unit 1082 acquires the period T and the threshold value θ stored in the storage unit 110.

FIG. 8 shows an example of transmission timing set autonomously and distributedly by each wireless communication device. As described above, the transmission timing is controlled by transmission timing control section 1082 of the wireless communication apparatus 100 _n. In FIG. 8, a case where T = 1, T ₀ = 1.1, and θ = 0.8 is shown as an example. 8, the wireless communication device ₁₀₀ 1, ..., 100 ₅ timer value of the phase, respectively phi _1, ..., represented by phi _5.

8 shows a case where the switch of the wireless communication device ₁₀₀ 1 -100 ₅ are turned on simultaneously. In other words, the initial phases of the wireless communication devices 100 _{1 to} 100 ₅ are synchronized. However, the same is true even if they are not turned on simultaneously. In other words, the present invention can be applied even when the initial phases of the wireless communication apparatuses 100 _{1 to} 100 ₅ are not synchronized. When the initial phase is not synchronized, the transmission timing control may be performed after the radio communication apparatuses 100 _{1 to} 100 ₅ are synchronized. As a synchronization method, for example, a pulse vibration connector system may be applied for synchronization. By performing transmission timing control after synchronization, a traveling wave pattern can be formed more quickly.

  Prior to data communication, each wireless communication device transmits and receives pulses.

The pulses transmitted by the wireless communication devices 100 _{1 to} 100 ₅ are referred to as first pulse to _fifth pulse, respectively.

First pulse transmitted by the wireless communication apparatus 100 ₁ is received by the wireless communication device 100 ₂ (1). The wireless communication apparatus 100 _{and second} phase when the first pulse is received is less than theta. Therefore, the wireless communication apparatus 100 ₂ is reset to zero phase.

Third pulse transmitted by the wireless communication device 100 ₃ is received by the wireless communication device 100 ₂ (2). The wireless communication apparatus 100 _{and second} phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after the receipt of the third pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1 (3). The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ , but the wireless communication device 100 ₁ is a sink node and therefore does not reset the phase. Wireless communication device 100 _third phase at which the second pulse is received is less than theta. Therefore, the wireless communication apparatus 100 ₃ resets to zero the phase.

The wireless communication devices 100 ₄ and 100 ₅ transmit the fourth and fifth pulses, respectively, when the phase reaches 1 (4) and (5). The fourth pulse transmitted by the wireless communication device 100 ₄ is received by the wireless communication devices 100 ₃ and 100 ₅ (4). However, the phase for the wireless communication apparatus 100 ₅ when receiving the pulses of said fourth sending the pulses is 1. Therefore, the wireless communication apparatus 100 _5, assuming no phase φ immediately after sending the fifth pulse. The radio communication device 100 the _third phase when a pulse of said 4 are received is higher theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after receiving said fourth pulse. The wireless communication apparatus 100 ₃ transmits the third pulse when the phase reaches 1 (6).

The third pulse is received by the wireless communication devices 100 ₂ and 100 ₄ . Wireless communication device 100 _fourth phase when the pulse of the third is received is less than theta. Therefore, the wireless communication device 100 ₄ is reset to zero phase. The wireless communication device 100 _{and second} phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after the receipt of the third pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1 (7).

The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ , but the wireless communication device 100 ₁ is a sink node and therefore does not reset the phase. Wireless communication device 100 _third phase at which the second pulse is received is less than theta. Therefore, the wireless communication apparatus 100 ₃ resets to zero the phase.

The wireless communication apparatus 100 ₅ transmits a fifth pulse when the phase reaches 1 (8). Fifth pulse transmitted by the wireless communication device 100 ₅ is received by the wireless communication apparatus 100 _4. Wireless communication device 100 _fourth phase when the pulse of the fifth has been received is not less than theta. Therefore, the wireless communication apparatus 100 ₄ does not reset to zero phase, also increases the phase after reception of the fifth pulse. The wireless communication apparatus 100 ₄ transmits the fourth pulse when the phase reaches 1 (9). The fourth pulse is received by the wireless communication devices 100 ₃ and 100 ₅ .

The wireless communication apparatus 100 ₅ phase when the pulse of the fourth is received is less than theta. Therefore, the wireless communication device 100 ₅ is reset to zero phase. On the other hand, the wireless communication device 100 _third phase when a pulse of the fourth was received is not less than theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after receiving said fourth pulse. The wireless communication apparatus 100 ₃ transmits the third pulse when the phase reaches 1 (10). The third pulse is received by the wireless communication devices 100 ₂ and 100 ₄ .

Wireless communication device 100 _fourth phase when the pulse of the third is received is less than theta. Therefore, the wireless communication device 100 ₄ is reset to zero phase. On the other hand, the wireless communication apparatus 100 _{and second} phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after the receipt of the third pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1 (11). The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ . Wireless communication device 100 _third phase at which the second pulse is received is less than theta. Therefore, the wireless communication apparatus 100 ₃ resets to zero the phase.

As shown in (8)-(11), the pulse transmitted by the wireless communication device 100 ₅ finally passes through the wireless communication device 100 ₄ , the wireless communication device 100 ₃ , and the wireless communication device 100 _2. it can be seen that is received by the wireless communication device 100 _1. In other words, the transmission timing in each wireless communication device can be controlled so that the packet transmitted by the wireless communication device 100 ₅ is received by the wireless communication device 100 ₁ . FIG. 8 shows, as an example, a case where the number of wireless communication devices is 5, but other than 5, in other words, can be applied to a case where there are a plurality of wireless communication devices.

  Even when each wireless communication device is arranged two-dimensionally, all wireless communication devices with hop count i from the sink node perform the same phase control on the pulses from the wireless communication devices i−1 and i + 1. Do. Accordingly, as in the case of the one-dimensional case described above, a traveling wave pattern can be formed by controlling the transmission timing.

<Transmission timing control method for spreading data>
FIG. 9 shows an example of a transmission timing control method when data is collected. The small arrow shown in FIG. 9 indicates that a pulse is wirelessly transmitted from the wireless communication device that is the original of the arrow to the wireless communication device that is the destination of the arrow.

9, the wireless communication device 100 ₁ is the source node, the wireless communication device ₁₀₀ 2, · · · 100 _n is a node other than the source node. In FIG. 9, as an example, a case where wireless communication devices 100 ₁ ,... 100 _n are arranged in a line is shown. Each wireless communication device can wirelessly communicate with an adjacent wireless communication device. In FIG. 9, data to be transmitted by the wireless communication device 100 ₁ is received in the order of the wireless communication devices 100 ₂ ,... 100 _n .

The wireless communication apparatus 100 _1, when the transmission timing control is started, T ₀ is set as the period of the phase of the timer value. Also, T is set as the period of the timer value phase in the wireless communication devices 100 ₂ ,... 100 _n when transmission timing control is started. When data is diffused, it is necessary to satisfy 2T / 3 <T ₀ and θ ≦ 2 (1− (T ₀ / T)).

The phase T ₀ of the phase of the timer value is stored in the storage unit 110 of the wireless communication apparatus serving as the source node as data necessary for transmission timing control. The transmission timing control unit 1082 acquires the period T ₀ stored in the storage unit 110.

  The phase T of the timer value and the threshold value θ are stored in the storage unit 110 of the wireless communication apparatus other than the source node as data necessary for controlling the transmission timing. The transmission timing control unit 1082 acquires the period T and the threshold value θ stored in the storage unit 110.

FIG. 10 shows an example of transmission timing set autonomously and distributedly by each wireless communication device. As described above, the transmission timing is controlled by transmission timing control section 1082 of the wireless communication apparatus 100 _n. FIG. 10 shows a case where T = 1, T ₀ = 0.9, and θ = 0.1 as an example. 10, the wireless communication device ₁₀₀ 1, ..., 100 ₅ timer value of the phase, respectively phi _1, ..., represented by phi _5.

FIG. 10 shows a case where the switches of the wireless communication devices 100 _{1 to} 100 ₅ are turned on at the same time. In other words, the initial phases of the wireless communication devices 100 _{1 to} 100 ₅ are synchronized. However, the same is true even if they are not turned on simultaneously. In other words, the present invention can be applied even when the initial phases of the wireless communication apparatuses 100 _{1 to} 100 ₅ are not synchronized. When the initial phase is not synchronized, the transmission timing control may be performed after the radio communication apparatuses 100 _{1 to} 100 ₅ are synchronized. As a synchronization method, for example, a pulse vibration connector system may be applied for synchronization. By performing transmission timing control after synchronization, a traveling wave pattern can be formed more quickly.

  Prior to data communication, each wireless communication device transmits and receives pulses.

The pulses transmitted by the wireless communication devices 100 _{1 to} 100 ₅ are referred to as first pulse to _fifth pulse, respectively.

First pulse transmitted by the wireless communication apparatus 100 ₁ is received by the wireless communication device 100 ₂ (1). The wireless communication apparatus 100 _{and second} phase when the first pulse was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after reception of the first pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1. The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ , but since the wireless communication device 100 ₁ is a source node, the phase is not reset. The wireless communication device 100 ₃ simultaneously with the reception of said second pulse, and transmits the third pulse. Therefore, the wireless communication apparatus 100 _3, assuming no phase φ immediately after receiving the second pulse.

First pulse transmitted by the wireless communication apparatus 100 ₁ is received by the wireless communication device 100 ₂ (2). The wireless communication apparatus 100 _{and second} phase when the first pulse was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after reception of the first pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1 (3). The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ , but since the wireless communication device 100 ₁ is a source node, the phase is not reset. On the other hand, the wireless communication device 100 _third phase at which the second pulse is received is not less than theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after reception of the second pulse. The wireless communication apparatus 100 ₃ transmits the third pulse when the phase reaches 1 (4).

The third pulse is received by the wireless communication devices 100 ₂ and 100 ₄ . The wireless communication apparatus 100 _4, simultaneously with the reception of the third pulse, and transmits the fourth pulse. Therefore, the wireless communication apparatus 100 _4, assuming no phase φ immediately after receiving the third pulse. On the other hand, the wireless communication apparatus 100 _{and second} phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after the receipt of the third pulse.

First pulse transmitted by the wireless communication apparatus 100 ₁ is received by the wireless communication device 100 ₂ (5). The wireless communication apparatus 100 _{and second} phase when the first pulse was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after reception of the first pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1 (6). The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ , but since the wireless communication device 100 ₁ is a source node, the phase is not reset. Meanwhile, the wireless communication device 100 _third phase when the second pulse is received at least theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after reception of the second pulse. The wireless communication apparatus 100 ₃ transmits the third pulse when the phase reaches 1 (7).

The third pulse is received by the wireless communication devices 100 ₂ and 100 ₄ . Wireless communication device 100 _fourth phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₄ does not reset to zero phase, also increases the phase after the receipt of the third pulse. The wireless communication apparatus 100 ₄ transmits the fourth pulse when the phase reaches 1 (8). The fourth pulse is received by the wireless communication devices 100 ₃ and 100 ₅ . The wireless communication apparatus 100 ₅ simultaneously with the reception of said fourth pulse, sending the fifth pulse. Therefore, the wireless communication apparatus 100 _5, assuming no phase φ immediately after receiving the fourth pulse. On the other hand, the wireless communication device 100 _third phase when a pulse of the fourth was received is not less than theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after receiving said fourth pulse.

First pulse transmitted by the wireless communication apparatus 100 ₁ is received by the wireless communication device 100 ₂ (9). The wireless communication apparatus 100 _{and second} phase when the first pulse was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after reception of the first pulse. The wireless communication apparatus 100 ₂ transmits a second pulse when the phase reaches 1 (10). The second pulse is received by the wireless communication devices 100 ₁ and 100 ₃ , but since the wireless communication device 100 ₁ is a source node, the phase is not reset. on the other hand. Wireless communication device 100 _third phase at which the second pulse is received is not less than theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after reception of the second pulse. The wireless communication apparatus 100 ₃ transmits the third pulse when the phase reaches 1 (11). The third pulse is received by the wireless communication devices 100 ₂ and 100 ₄ . The wireless communication apparatus 100 _{and second} phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₂ without resetting to zero the phase, also increases the phase after the receipt of the third pulse. On the other hand, the wireless communication device 100 _fourth phase when the pulse of the third was received is not less than theta. Therefore, the wireless communication apparatus 100 ₄ does not reset to zero phase, also increases the phase after the receipt of the third pulse. The wireless communication apparatus 100 ₄ transmits the fourth pulse when the phase reaches 1 (12).

The fourth pulse is received by the wireless communication devices 100 ₃ and 100 ₅ . Wireless communication device 100 _third phase when a pulse of the fourth was received is not less than theta. Therefore, the wireless communication apparatus 100 ₃ without resetting to zero the phase, also increases the phase after receiving said fourth pulse. On the other hand, the wireless communication apparatus 100 ₅ phase when the pulse of the fourth was received is not less than theta. Therefore, the wireless communication device 100 ₅ is not reset to zero phase, also increases the phase after receiving said fourth pulse.

As shown in (9)-(12), the pulse transmitted by the wireless communication device 100 _{1 is} transmitted through the wireless communication device 100 ₂ , the wireless communication device 100 ₃ , and the wireless communication device 100 _4. 100 ₅ is received. In other words, the packet transmitted by the wireless communication device 100 ₁ can control the transmission timing of each wireless communication device to be received in the wireless communication apparatus 100 _5. FIG. 10 shows, as an example, a case where the number of wireless communication apparatuses is 5, but other than 5, in other words, it can be applied to a case where there are a plurality of wireless communication apparatuses.

  Even when each wireless communication device is arranged two-dimensionally, all wireless communication devices with hop count i from the source node perform the same phase control on the pulses from the wireless communication devices i−1 and i + 1. Do. Accordingly, as in the case of the one-dimensional case described above, a traveling wave pattern can be formed by controlling the transmission timing.

<Mode control>
In the present wireless communication system, each wireless communication device 100 _n may switch between the active mode and the sleep mode immediately after the start of wireless communication. A traveling wave pattern can be formed even when the switching is performed.

11 and 12 show an example of timing for performing mode control. The mode control unit 1086 of each wireless communication device 100 _n controls the mode by the method described below.

<Timing control method for mode control when collecting data>
FIG. 11 shows the timing of mode control when data is collected. In FIG. 11, the horizontal axis is time.

When collecting data, the mode transits to the active mode for a certain time after the pulse transmission. After the transition to the active mode for the predetermined time, the transition to the sleep mode is made. As shown in FIG. 8, each wireless communication device receives data from other wireless communication devices after transmitting data. When transitioning to the active mode, the time of the active mode is set so that the time of the active mode> the period T ₀ of the wireless communication apparatus that is set as the sink node−the period T of the wireless communication apparatus other than the sink node.

<Timing control method for mode control when data is spread>
FIG. 12 shows the timing of mode control when data is spread. In FIG. 12, the horizontal axis represents time.

When spreading data, the mode transits to the active mode for a certain period of time before pulse transmission. After the pulse transmission, the mode transits to the sleep mode. As shown in FIG. 10, each wireless communication device 100 _n receives data from other wireless communication devices before transmitting data. When transitioning to the active mode, the time of the active mode is set so that the time of the active mode <the period T of the wireless communication apparatus other than the source node—the period T ₀ of the wireless communication apparatus that is the source node.

<Operation of this wireless communication device>
The operation of this wireless communication apparatus will be described.

  FIG. 13 is a flowchart showing the operation of a wireless communication apparatus other than the sink node or source node.

The wireless communication device 100 _n determines whether a pulse has been received (step S1302). For example, a pulse from another wireless communication device is received by the reception unit 106 and input to the transmission timing control unit 1082. The transmission timing control unit 1082 determines whether a pulse has been received from another wireless communication device.

If it is not determined that it has received the pulse (Step S1302: NO), the wireless communication apparatus 100 _n advances the phase phi (step S1304). For example, the transmission timing control unit 1082 advances the phase φ indicated by the sawtooth wave.

The wireless communication device 100 _n determines whether or not the phase φ is 1 or more (step S1306). For example, the transmission timing control unit 1082 determines whether or not the phase φ is 1 or more.

When it is not determined that the phase φ is 1 or more, in other words, when the phase φ is less than 1 (step S1306: NO), the process returns to step S1302. Steps S1302 to S1306 are performed until the phase φ becomes 1 or more. On the other hand, when it is determined that the phase φ is 1 or more (step S1306: YES), the wireless communication 100 _n transmits a pulse (step S1308). For example, the transmission timing control unit 1082 performs control to transmit a pulse to the transmission unit 104 when it is determined that the phase φ is 1 or more. The transmission unit 104 transmits a pulse from the antenna 102 in accordance with control by the transmission timing control unit 1082.

The wireless communication device 100 _n transmits a pulse in step S1308, and then determines the phase after the pulse transmission. The wireless communication device 100 _n determines whether the phase φ ′ when receiving a pulse from another wireless communication device is not zero before transmitting the pulse (step S1310). For example, the transmission timing control unit 1082 holds the phase φ ′ when receiving a pulse from another wireless communication device in the storage unit 110 before transmitting the pulse.

When it is determined that the phase φ ′ is zero (step S1310: NO), the wireless communication device 100 _n sets the phase φ to zero and returns to step S1302. For example, when the transmission timing control unit 1082 determines that the phase φ ′ is zero, the transmission timing control unit 1082 sets the phase φ to zero. On the other hand, when the phase the? 'Is determined not to be zero (step S1310: YES), the wireless communication apparatus 100 _n includes phase the?' Phase phi, as zero phase the? ', The flow returns to step S1302. For example, when the transmission timing control unit 1082 determines that the phase φ ′ held in the storage unit 110 is not zero, the transmission timing control unit 1082 sets the phase φ to the phase φ ′ and the phase φ ′ to zero.

If it is determined in step S1302 that a pulse has been received (step S1302: YES), the wireless communication device 100 _n determines whether or not the phase φ is less than the threshold θ (φ <θ) (step S1318), for example. When it is determined that the pulse is received, the transmission timing control unit 1082 determines whether or not the phase φ is less than the threshold θ.

If the phase phi is determined to be less than the threshold value theta (Step S1318: YES), the wireless communication apparatus 100 _n includes a zero phase phi, the flow returns to step S1302. For example, when it is determined that the phase φ is less than the threshold θ, the transmission timing control unit 1082 resets the phase φ by setting it to zero. On the other hand, when the phase φ is determined not less than the threshold value theta (Step S1318: NO), if in other words the phase φ is determined to or greater than the threshold value theta, wireless communication apparatus 100 _n includes a phase the? '(1-phase φ ), The process returns to step S1302. For example, if the phase φ is not determined to be less than the threshold θ, the transmission timing control unit 1082 sets the phase φ ′ to (1−phase φ).

  FIG. 14 is a flowchart illustrating the operation of the wireless communication apparatus that is a sink node or a source node.

The wireless communication device 100 _n advances the phase φ (step S1402). For example, the transmission timing control unit 1082 advances the phase φ indicated by the sawtooth wave.

The wireless communication device 100 _n determines whether or not the phase φ is 1 or more (step S1404). For example, the transmission timing control unit 1082 determines whether or not the phase φ is 1 or more.

When it is not determined that the phase φ is 1 or more, in other words, when the phase φ is less than 1 (step S1404: NO), the process returns to step S1402. Steps S1402 to S1404 are performed until the phase φ becomes 1 or more. On the other hand, when it is determined that the phase φ has become 1 or more (step S1404: YES), the wireless communication 100 _n transmits a pulse and resets the phase φ to zero (step S1404). For example, the transmission timing control unit 1082 performs control to transmit a pulse to the transmission unit 104 when it is determined that the phase φ is 1 or more. The transmission unit 104 transmits a pulse from the antenna 102 in accordance with control by the transmission timing control unit 1082. After transmitting a pulse and setting the phase φ to zero, the process returns to step S1402.

The present embodiment can be applied even when the wireless communication device _100n is arranged three-dimensionally.

  FIG. 15 shows an example in which the wireless communication devices according to the present embodiment are arranged in three dimensions. 100 nodes with a communication radius of 30 were randomly placed in a 200x200 range, and a sink node was placed at the center. The sync node cycle is 1.1 with respect to the normal node cycle 1. Each point is a node, and a node immediately after pulse transmission, a sync node, and a node other than the sync node are shown. It was confirmed that pulses were transmitted in a traveling wave pattern that went from the outside of the network to the central sink node in order from a random initial phase.

  Similarly, when data is diffused, pulses are transmitted in a traveling wave pattern directed from the inside of the network to the outside nodes in order after a predetermined time has elapsed from the random initial phase.

  According to this wireless communication system, data collection can be performed quickly and efficiently by controlling the communication timing of each wireless communication apparatus so as to form a traveling wave toward the wireless communication apparatus that is a sink node. In addition, data diffusion can be performed quickly and efficiently by controlling the communication timing of each wireless communication device so as to form a traveling wave from the wireless communication device serving as a source node.

  According to this wireless communication system, each wireless communication apparatus can determine communication timing in an autonomous and distributed manner without requiring a reference station for managing communication timing.

  According to this wireless communication system, the transmission timing can be controlled without managing the hop number information from the sink node or the source node.

  According to this wireless communication system, each wireless communication device can switch between the active mode and the sleep mode from the time of startup. Since the mode can be switched to the sleep mode, power consumption can be reduced.

According to this wireless communication system, data is appropriately set by appropriately setting the cycle T ₀ of the wireless communication device that is the sink node or the source node and the threshold value θ of each wireless communication device through data transmission or the like as necessary. Collection / spreading can be switched.

  A similar traveling wave is confirmed even when data is diffused.

  Although the present invention has been described above with reference to specific embodiments, each embodiment is merely an example, and those skilled in the art will understand various variations, modifications, alternatives, substitutions, and the like. I will. For convenience of explanation, an apparatus according to an embodiment of the present invention has been described using a functional block diagram, but such an apparatus may be implemented in hardware, software, or a combination thereof. The present invention is not limited to the above-described embodiments, and various variations, modifications, alternatives, substitutions, and the like are included without departing from the spirit of the present invention.

5, 10, 11, 12, 13, 21, 22, 23, 24 Sensor node 100 _n (n is an integer of n> 0) Wireless communication device 102 Antenna 104 Transmitting unit 106 Receiving unit 108 Control unit 1082 Transmission timing control unit 1084 Transmission data generation unit 1086 Mode control unit 110 Storage unit 112 Sensor

Claims (7)

A wireless communication device in a wireless communication system including a plurality of wireless communication devices,
According to the phase indicated by the sawtooth wave, a transmission timing control unit that controls to transmit a pulse at a timing at which the phase reaches a maximum value;
A transmission unit for transmitting a pulse according to the timing controlled by the transmission timing control unit,
The transmission timing control unit sets the phase to zero when the phase when a pulse is received from another wireless communication device is less than a predetermined threshold, and the phase when the pulse is received from the other wireless communication device. A wireless communication apparatus that sets a value obtained by subtracting the phase from the maximum value after the phase reaches a maximum value when the phase is equal to or greater than a predetermined threshold. The wireless communication device according to claim 1,
The transmission timing control unit, when transmitting data to another wireless communication device from which data is to be collected, should be followed by the wireless communication device in a cycle shorter than the sawtooth cycle to be followed by the other wireless communication device. Set the sawtooth wave cycle,
Furthermore, when the threshold is θ, the period of the sawtooth wave that the other wireless communication apparatus should follow is T ₀ , and the period of the sawtooth wave that the wireless communication apparatus is to follow is T,
2 ((T ₀ / T) -1) <θ ≦ 2- (T ₀ / T)
A wireless communication apparatus that controls the phase according to a threshold indicated by. The wireless communication device according to claim 2,
A mode control unit that transitions to an active mode for a certain period of time after a pulse is transmitted by the transmission unit;
The mode control unit sets the time of the active mode so that the time of the active mode> the period of the sawtooth wave to be followed by the other radio communication apparatus−the period of the sawtooth wave to be followed by the radio communication apparatus. Communication device. The wireless communication device according to claim 1,
The transmission timing control unit, when transmitting data from another wireless communication device to which data is to be spread, uses T ₀ as the period of the sawtooth wave to be followed by the other wireless communication device, and the saw to be followed by the wireless communication device. If the wave period is T,
2T / 3 <T ₀
Set the period of the sawtooth wave that the wireless communication device should follow,
Furthermore, when the threshold is θ,
θ ≦ 2 (1- (T ₀ / T))
A wireless communication apparatus that controls the phase according to a threshold indicated by. The wireless communication apparatus according to claim 4, wherein
Before a pulse is to be transmitted by the transmission unit, a mode control unit for transitioning to an active mode for a certain period of time,
The mode control unit sets the time of the active mode so that the time of the active mode <the period of the sawtooth wave to be followed by the wireless communication apparatus−the period of the sawtooth wave to be followed by the other wireless communication apparatus. Communication device. A wireless communication system including a plurality of wireless communication devices,
The wireless communication device includes a wireless communication device that collects or spreads data and a wireless communication device other than the wireless communication device,
The other wireless communication device is:
According to the phase indicated by the sawtooth wave, a transmission timing control unit that controls to transmit a pulse at a timing at which the phase reaches a maximum value;
A transmission unit for transmitting a pulse according to the timing controlled by the transmission timing control unit,
The transmission timing control unit sets the phase to zero when the phase when a pulse is received from another wireless communication device is less than a predetermined threshold, and the phase when the pulse is received from the other wireless communication device. When the phase is equal to or greater than a predetermined threshold, after the phase reaches the maximum value, set to a value obtained by subtracting the phase from the maximum value,
The wireless communication device
According to the phase indicated by the sawtooth wave, a transmission timing control unit that controls to transmit a pulse at a timing at which the phase reaches a maximum value;
A radio communication system comprising: a transmission unit that transmits a pulse according to a timing controlled by the transmission timing control unit. A transmission timing control method in one wireless communication device in a wireless communication system including a plurality of wireless communication devices,
A transmission timing control step for controlling to transmit a pulse at a timing at which the phase reaches a maximum value according to the phase indicated by the sawtooth wave;
A transmission step of transmitting a pulse according to the timing controlled by the transmission timing control step,
The transmission timing control step sets the phase to zero when the phase when a pulse is received from another wireless communication device is less than a predetermined threshold, and the phase when the pulse is received from the other wireless communication device. A transmission timing control method for setting a value obtained by subtracting the phase from the maximum value after the phase reaches a maximum value when the phase is equal to or greater than a predetermined threshold.

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