JP4967742B2 - Communication terminal device - Google Patents

Description

  The present invention relates to a communication terminal device, and more particularly to a communication terminal device that periodically transmits information to communicate with other communication terminal devices.

  For example, a TDMA method is known as one of communication methods for periodically transmitting information and communicating with other communication terminal devices. For example, when this TDMA method is used in communication such as a wireless LAN or a cellular phone, each communication terminal apparatus uses a single frequency and each frame repeated in a predetermined cycle is divided into slots. This is a communication method in which data is communicated in packets.

Conventionally, a technique for controlling slot assignment to each communication terminal device and transmission cycle of each communication terminal device by exchanging request packets, information packets, response packets, and the like between the communication terminal devices has been known. (For example, refer nonpatent literature 1). As a result, it is possible to suppress a decrease in data transfer efficiency.
Kanzaki Emitsu, Kamikata Toshiaki, Hara Takahiro, Nishio Shojiro “TDMA Slot Allocation Method According to Changes in the Number of Terminals in Ad Hoc Networks” (Information Processing Society of Japan Vol. 45 No. 3 Mar 2004)

  However, in the technique described in Non-Patent Document 1, in order to control slot assignment to each communication terminal device and transmission cycle of each communication terminal device, a request packet, an information packet, and Since response packets are exchanged, there is a problem that the control becomes complicated. Further, the communication terminal apparatus finds a period during which the peripheral communication terminal apparatus is not transmitting a packet, and transmits a packet having a technique described in Non-Patent Document 1 or a communication terminal apparatus that transmits a packet in the predetermined period. In a communication terminal device for transmission, when the transmission cycle of each communication terminal device becomes longer, each mobile body (for example, a vehicle) equipped with each communication terminal device does not always transmit at least one packet during a predetermined time. If the communication terminal device of the receiving side cannot guarantee the time interval for receiving information, and if the communication cycle of each communication terminal device is shortened, packets will be transmitted frequently, increasing communication traffic and exceeding the allowable amount. There is a problem that communication becomes impossible.

  The present invention has been made in order to solve the above-described problems. The transmission period is such that communication traffic is suppressed by simple control and at least one packet can be transmitted during a predetermined interval (predetermined time). An object of the present invention is to provide a communication terminal device that controls the communication.

  In order to achieve the above object, a communication terminal device according to a first invention is a communication terminal device mounted on a mobile body, and a receiving means for receiving packets transmitted from a peripheral communication terminal device in a predetermined cycle; A transmission cycle determined based on a moving distance determined to transmit at least one packet during movement of a specified distance and a speed of the moving body based on a reception state when the packet is received by the receiving unit Determining means for determining a transmission cycle so as not to exceed an upper limit value of the transmission object or a predetermined upper limit value of the transmission period according to the position of the mobile body, and transmitting a packet at the transmission cycle determined by the determination means And transmitting means.

  According to the communication terminal device of the first invention, the determining means determines to transmit at least one packet during the movement of the specified distance based on the reception status when the receiving means receives the packet. Since the transmission cycle is determined so as not to exceed the upper limit value of the transmission cycle determined based on the moving distance and the speed of the moving body, or the upper limit value of the transmission cycle determined in advance according to the position of the moving body, Without exchanging request packets, information packets, response packets, and the like between terminal devices, it is possible to transmit at least one packet during a predetermined interval while suppressing communication traffic with simple control.

  In order to achieve the above object, a communication terminal apparatus according to a second invention is a communication terminal apparatus mounted on a mobile body, transmitted from the peripheral communication terminal apparatus at a predetermined cycle, and the peripheral communication terminal Based on the data indicating the reception status included in the packet received by the receiving means, the receiving means for receiving the packet including the data indicating the reception status when the device receives the packet, during the movement of the specified distance An upper limit value of a transmission cycle determined based on a moving distance determined to transmit at least one packet and a speed of the moving body, or an upper limit value of a transmission cycle determined in advance according to the position of the moving body. A determination means for determining a transmission cycle so as not to exceed, a packet including data indicating a reception status when the packet is received by the transmission period determined by the determination means; It is configured to include a transmission unit for signal for, a.

  According to the communication terminal device of the second invention, the determining means transmits at least one packet during the movement of the specified distance based on the data indicating the reception status included in the packet received by the receiving means. The transmission cycle is set so as not to exceed the upper limit value of the transmission cycle determined based on the moving distance determined to be performed and the speed of the moving body, or the upper limit value of the transmission cycle determined in advance according to the position of the moving body. Therefore, without exchanging request packets, information packets, response packets, and the like between the communication terminal devices, the communication traffic is suppressed with simple control, and at least one packet is transmitted during a predetermined interval. be able to.

  In the communication terminal apparatus according to the first invention, the receiving means can receive a packet transmitted from a peripheral communication terminal apparatus in a slot unit in which each frame repeated at a predetermined period is time-divided.

  Also, in the communication terminal apparatus according to the second invention, the receiving means transmits each frame repeated at a predetermined cycle from the peripheral communication terminal apparatus in a time-divided slot unit, and the peripheral communication terminal apparatus transmits a packet It is possible to receive a packet including data indicating the reception status when receiving.

  Further, in the communication terminal apparatus according to the first invention and the communication terminal apparatus according to the second invention, the determining means is a transmission determined according to a ratio of the number of used slots to the total number of slots of each of the frames. When the transmission period determined according to the period or the use state of the communication band in each frame exceeds the upper limit value of the transmission period, the upper limit value may be determined as the transmission period. Thereby, for example, by setting the transmission cycle so that the transmission cycle becomes longer as the ratio of the number of used slots to the total number of slots increases, the transmission cycle can be determined so that there are more empty slots, Further, according to the amount of communication traffic occurring within one frame period, for example, the transmission period can be determined so that traffic within one frame period can be accommodated. As a result, an effect of suppressing communication traffic can be obtained.

  As described above, according to the communication terminal device of the present invention, the transmission cycle for transmitting data is determined based on the received packet so as not to exceed the upper limit value of the transmission cycle. The effect that it is possible to transmit at least one packet during a predetermined interval while suppressing communication traffic with simple control without exchanging request packets, information packets, response packets, and the like between terminal devices. Is obtained.

[First embodiment]
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In this embodiment, the communication terminal device to which the present invention is applied is mounted on a moving body such as a vehicle, and wireless communication is performed by exchanging packets as communication information between a plurality of communication terminal devices. explain. In the present embodiment, a communication terminal apparatus that employs the TDMA system as an example of a communication system that periodically transmits information to communicate with other communication terminal apparatuses will be described.

  As shown in FIG. 1, the communication terminal apparatus 10 according to the first embodiment of the present invention is provided with a reception circuit 12 that receives a packet transmitted by another communication terminal apparatus via a reception antenna 11. Yes. The reception circuit 12 is connected to the packet detection unit 13.

  The packet detector 13 detects which slot the received packet is transmitted from. The packet detector 13 is connected to the packet demodulator 14 and the frame information generator 15.

  The packet demodulator 14 demodulates the data transmitted from the received packet. The frame information generation unit 15 generates frame information to be embedded in the transmission packet based on the use state of the slot in which the packet detection unit 13 has detected the packet and the success or failure of the packet demodulation by the packet demodulation unit 14. The packet demodulation unit 14 and the frame information generation unit 15 are connected to the information storage unit 16.

  The information storage unit 16 stores the frame information included in the data demodulated by the packet demodulation unit 14 and the frame information generated by the frame information generation unit 15 for a predetermined number of frames. Although details will be described later, the frame information included in the data demodulated by the packet demodulator 14 is frame information generated in the peripheral communication terminal device, and the frame information generated by the frame information generator 15 is Frame information generated in the communication terminal device 10. The information storage unit 16 is connected to the transmission cycle determination unit 17.

  The transmission cycle determination unit 17 is determined to transmit at least one packet during various types of information stored in the information storage unit 16, the speed of the moving body from the vehicle speed sensor (not shown), and the movement of the specified distance. Based on the travel distance (for example, 5 m), a transmission slot which is a slot for transmitting a packet and a transmission cycle for transmitting at least one packet while the mobile body travels the travel distance are determined. The transmission cycle determination unit 17 and the frame information generation unit 15 are connected to the packet generation unit 18. The transmission cycle determination unit 17 is connected to the transmission timing control unit 19.

  The packet generation unit 18 generates a packet, and the transmission timing control unit 19 controls the packet transmission timing. The packet generator 18 and the transmission timing controller 19 are connected to the transmitter circuit 20.

  The transmission circuit 20 transmits a packet via the transmission antenna 21.

  FIG. 2 shows a data structure of a packet transmitted and received by communication terminal apparatus 10 according to the present embodiment.

  In communication terminal apparatus 10 according to the present embodiment, frames are periodically repeated, and each frame is configured by slots divided into n periods (four in this embodiment). Yes. This one slot indicates a period during which one packet can be transmitted. The communication terminal apparatus 10 exchanges packets in units of this slot. Note that the period of one frame may be set according to the basic period of data transmission of each communication terminal device. For example, if the basic period of each communication terminal is 100 ms, the period of one frame may be set to 100 ms. In communication terminal apparatus 10 according to the present embodiment, it is assumed that the frame period is 100 ms.

  Further, communication terminal apparatus 10 according to the present embodiment can set the transmission cycle for transmitting a packet to any one of a power of 2 times the frame. The period is 1 time (basic period, eg 0.1 sec), 2 times (2 times period, eg 0.2 sec), 4 times (4 times period, eg 0.4 sec), 8 times (8 times) It can be set to any one of five periods (for example, 0.8 sec) and 16 times (16 times period, for example, 1.6 sec).

  The packet includes header information, frame information indicating the use status of a slot in one frame in the communication terminal device that transmitted the packet, transmission cycle information indicating a cycle in which the packet is transmitted, and actual data to be transmitted. , And a guard time for reducing the influence of the synchronization error of the slot. In the present invention, the slot synchronization method is not limited, but it is assumed that synchronization is achieved to the extent that it can be compensated by the guard time by some means such as providing a reference station for synchronization.

  The frame information is provided with an area corresponding to the number of slots, and a value indicating the reception status in each slot, for example, the usage status of each slot, is set in each area. In the frame information according to the present embodiment, four areas [S1, S2,..., S4] are provided corresponding to the four slots. In each area of the frame information, a value indicating one of “FREE” (empty), “ACK” (reception success), “NACK” (reception failure), and “RTC” (collision occurrence) is a frame information generation unit. 15 is set.

  “FREE” indicates that no packet was detected in the target slot. “ACK” indicates that the packet was correctly received in the target slot, that is, the packet was detected and the data restoration was successful. “NACK” indicates that the reception of the packet has failed in the target slot, that is, the data restoration has failed even though the packet has been detected. “RTC” indicates that a packet collision from the peripheral communication terminal apparatus has occurred in the target slot.

  Each area of the frame information is a 2-bit area. In the case of “FREE”, “00” is set, in the case of “ACK”, “01” is set, and in the case of “NACK”, When “10” is set and “RTC” is set, “11” is set.

  In addition, the transmission cycle information according to the present embodiment is a 3-bit area, and when the packet transmission cycle is 1 time the frame, “000” is set, and the packet transmission cycle is the frame If it is 2 times, “001” is set. If the cycle for transmitting the packet is 4 times the frame, “010” is set. If the cycle for transmitting the packet is 8 times the frame, “011” is set. When the packet transmission period is 16 times the frame, “100” is set.

  Next, the operation of communication terminal apparatus 10 according to the present embodiment when wireless communication is performed by exchanging packets with other communication terminal apparatuses (peripheral communication terminal apparatuses) will be described.

  When receiving a packet transmitted from another communication terminal device, the communication terminal device 10 operates as follows.

  The packet detection unit 13 detects in which slot the packet is transmitted based on the reception time of the packet received by the reception circuit 12. The packet demodulator 14 demodulates the detected packet and restores data sent from another communication terminal device.

  The frame information generation unit 15 detects “FREE” for each slot for which the packet has not been detected by the packet detection unit 13 for each slot for the last one frame received, detects the packet by the packet detection unit 13, and performs packet demodulation. "ACK" for a slot in which the packet was successfully demodulated in the unit 14, "NACK" for a slot in which the packet was detected in the packet detector 14 and the packet was not demodulated in the packet demodulator 14, and the packet detector 13 Frame information “RTC” is generated for the slot in which a packet collision is detected.

  The information storage unit 16 extracts frame information [S1, S2,..., S4] of other communication terminal devices included in the data from the data demodulated by the packet demodulation unit 14 by the frame information generation unit 15, The extracted frame information is used as frame information (other terminal frame information) generated by another communication terminal device, attached with information indicating the received slot, and a predetermined number of frames are stored in order from the newest one. Further, the information storage unit 16 stores the predetermined frames in order from the newest one, using the frame information generated by the frame information generation unit 15 as the frame information of the communication terminal device 10 (own terminal frame information). In communication terminal device 10 according to the present embodiment, since the longest transmission cycle is 16 times the frame, information storage unit 16 stores data for 16 frames.

  The transmission cycle determination unit 17 determines the slot used for packet transmission and the packet transmission cycle based on the other terminal frame information for the predetermined frame stored in the information storage unit 16 and the own terminal frame information.

  Specifically, the transmission cycle determination unit 17 determines as follows based on the other terminal frame information and the own terminal frame information for the predetermined frame stored in the information storage unit 16.

  First, for each slot, the transmission cycle determination unit 17 determines the use state of the slot indicated by the other terminal frame information and the own terminal frame information for the predetermined frame, and at least one of the use states is “ACK”. , “NACK” or “RTC” indicates that the slot is being used by another communication terminal device, prohibits the use of the slot, and sets “FREE” in all usage states. Regarding the slot shown, it is determined that the slot is an empty slot (a slot not used by any communication terminal device). Then, the transmission cycle determining unit 17 determines an empty slot as a transmission slot used for packet transmission. Further, the transmission cycle determination unit 17 determines the cycle of one frame as the basic cycle of packet transmission. Note that, when there are a plurality of empty slots, the transmission cycle determination unit 17 according to the present embodiment uses, for example, in order from the earliest timing within one frame. Alternatively, they can be used in the order of late timing within one frame.

  The packet generation unit 18 generates a packet in which the frame information generated by the frame information generation unit 15 and the cycle information indicating the transmission cycle of the packet determined by the transmission cycle determination unit 17 are embedded in order to transmit the transmission data. . The transmission timing control unit 19 controls the transmission circuit 20 so as to transmit a packet at the timing corresponding to the transmission slot determined by the transmission cycle determination unit 17. The transmission circuit 20 transmits the packet generated by the packet generation unit 18 via the transmission antenna 21 according to the control from the transmission timing control unit 19.

  In addition, when transmission of a packet is started by the transmission antenna 21, the transmission cycle determination unit 17 performs the following determination on a transmission slot and a transmission cycle for transmitting data for each frame after the next frame.

  First, the transmission slot is determined as follows.

  The transmission cycle determination unit 17 includes, in the other terminal frame information of the latest one frame stored in the information storage unit 16, when there is even one in which the use state of the transmission slot indicates “ACK” or “NACK”, The transmission slot is determined to be reserved by the communication terminal apparatus 10, and the same slot is determined as the transmission slot in the next frame. In addition, the transmission cycle determination unit 17 determines that the other terminal frame information stored in the information storage unit 16 has one of the transmission slot usage states indicating “RTC”. It is determined that a collision with a packet transmitted from the communication terminal apparatus has occurred, and another empty slot is determined as a new transmission slot in the next frame.

  Next, determination of a transmission cycle for transmitting data will be described.

  FIG. 3 is a diagram showing a flowchart of a transmission cycle determination processing routine for determining the transmission cycle executed by the transmission cycle determination unit 17, and FIG. 4 shows the transmission cycle determination unit 17 for executing the transmission cycle determination processing routine. It is the figure represented with the functional block.

  As shown in FIG. 4, when the transmission cycle determination unit 17 that executes the transmission cycle determination processing routine is represented by a functional block, the transmission cycle upper limit value calculation unit 30 that calculates the upper limit value of the transmission cycle, the communication status (for example, slot usage) A communication status calculation unit 32 that calculates a rate or a communication band usage status) and a transmission cycle determination unit 34 that determines a transmission cycle for transmitting transmission data.

  When the transmission of the packet is started by the transmission antenna 21, the transmission cycle determination processing routine shown in FIG.

  First, in step 100, the upper limit value of the transmission cycle is calculated. For example, in step 100, as shown in the graph of FIG. 5A, the communication terminal apparatus 10 is mounted using a movement distance determined to transmit at least one packet during movement of a specified distance. A transmission cycle necessary for transmitting at least one packet while the mobile body travels a moving distance is calculated by the following equation (1). In the present embodiment, an example in which the maximum value of the movement distance is set to 5 m will be described.

  However, a in equation (1) is the maximum value of the moving distance, in this case, a = 5 [m], X is the speed of the moving body, and Y is the transmission period. In this embodiment, the transmission period is 0.1 sec (basic period), 0.2 sec (double period), 0.4 sec (4 times period), 0.8 sec (8 times period), and 1 sec. .6 sec (16 times period), so transmission is performed from the velocity X of the moving object by the discrete graph shown in FIG. 5B, which does not exceed the transmission cycle Y shown in the graph of FIG. Calculate the upper limit of the period. For example, as shown in the figure, when the speed X of the moving object is 25 m / s, the calculation result of the upper limit value of the transmission cycle is 0.2 sec, and when the speed X of the moving object is 10 m / s, The calculation result of the upper limit value of the transmission cycle is 0.4 sec.

In addition, the graph showing the upper limit value of the transmission period shown in FIG. 5B is the speed between v _{1 and} v ₂ and between the speeds v _{3 and} v ₄ in order to prevent chattering, as shown in FIG. Between the speeds v ₅ and v ₆ and between the speeds v _{7 and} v ₈ , there is a hysteresis characteristic with respect to the speed X of the moving body. Although details will be described later, in the relationship between the slot usage rate or communication band usage status and the determined transmission cycle, the slot usage rate or communication bandwidth usage status also has hysteresis characteristics.

  In the next step 102, the communication status in each frame is calculated. At this time, as an observation area for observing the communication status in each frame, the communication terminal device 10 includes a communication terminal device 10 and a peripheral communication terminal device with which the communication terminal device 10 can communicate. In the present embodiment, this case will be described with reference to FIG. 6 because an area that does not include a hidden terminal that is not communicable with the communication terminal apparatus 10 is considered as an observation area.

  The observation area in this case includes, for example, peripheral communication terminal devices B, C, and D with which the communication terminal device A (this communication terminal device 10) can communicate, as shown in FIG. Communication terminal device E that is a hidden terminal that communication terminal device B can communicate but communication terminal device A cannot communicate with, and its own communication terminal device A cannot communicate, and peripheral communication terminal devices B, C, and D also communicate Since an observation area 61 that does not include the communication terminal device F that is not possible is considered, this observation area 61 will be described below as an example.

As shown in FIG. 6B, in one frame from time t ₀ to time t ₁ , among the slots 1 to 4, the communication terminal device B and the communication terminal device C communicate using the slot 1, If the communication terminal apparatus a and communication terminal apparatus D is communicating with a slot 3, the communication terminal apparatus a, frame information such as: at time t ₁ is generated. That is, the communication terminal device A detects that the packet from the communication terminal device B and the packet from the communication terminal device C collide with each other in the slot 1, and the packet from the communication terminal device D in the slot 3 As shown in FIG. 6C, “RTC” is associated with the area S1, “FREE” is associated with the areas S2 and S4, and “ACK” is associated with the area S3. The frame information set and set is generated.

  Then, from the reception status indicated by each area of the generated frame information, as a communication status, for example, a slot usage rate which is a ratio of the number of used slots to the total number of slots of each frame is expressed by the following equation (2). Calculate by

  In the present embodiment, the total number of slots is “4” and the “number of FREE” is “2”, so (4-2) /4=0.5, and the slot usage rate is 50%. It becomes.

  In addition, although the example which calculates a slot usage rate as a communication condition was demonstrated above, the use condition of a communication band as a communication condition is calculated from the reception condition which each area | region of the produced | generated frame information shows by the following formula | equation (3). May be.

  Here, α is the number of communication terminal apparatuses in which packet collision occurs due to transmission of packets using the same slot. In this embodiment, the total number of slots is “4”, the number of “RTC” is “1”, the number of “ACK” is “1”, and the number of “NACK” is “0”. ", And since the communication terminal apparatus B and the communication terminal apparatus C use the same slot 3 and a packet collision occurs, α is" 2 ", so (1 × 2 + 1 + 0) /4=0.75, The usage status of the communication band is 75%.

  In the next step 104, a new transmission cycle is calculated based on the slot usage rate or communication band usage status calculated in step 102. For example, in step 104, when the slot usage rate is calculated in step 102, when the calculated slot usage rate exceeds a predetermined value, for example, 40%, a new transmission period is set to be longer than the current transmission cycle. The transmission cycle is calculated. For example, a cycle twice as large as the current transmission cycle is calculated as a new transmission cycle. When the transmission cycle is less than 40%, the current transmission cycle is directly calculated as a new transmission cycle. In addition, when the usage status of the communication band is calculated in step 102, when the calculated usage status of the communication band exceeds a predetermined value, for example, 50%, in order to suppress communication traffic, A new transmission cycle is calculated so as to be longer. For example, a cycle that is twice the current transmission cycle is calculated as a new transmission cycle. When the transmission cycle is less than 50%, the current transmission cycle is directly calculated as a new transmission cycle. To do.

  Note that the calculation method of the new transmission cycle in step 104 is not limited to the one described above, and the transmission cycle is calculated based on the slot usage rate or the communication band usage status using other methods. May be. For example, when the usage status of the communication band is calculated in step 102 in step 104, the calculated usage status of the communication band is a predetermined value different from the predetermined value, for example, less than 30%. May calculate a new transmission cycle so as to be shorter than the current transmission cycle, and in the case of 30% or more, the current transmission cycle may be calculated as it is as a new transmission cycle.

  In the next step 106, it is determined whether or not the transmission cycle calculated in step 104 exceeds the upper limit value of the transmission cycle calculated in step 100.

  If an affirmative determination is made in step 106, in the next step 108, the upper limit value of the transmission cycle calculated in step 100 is determined as a transmission cycle for transmitting transmission data. On the other hand, if a negative determination is made in step 106, in the next step 110, the transmission cycle calculated in step 104 is determined as a transmission cycle for transmitting transmission data. For example, the upper limit value of the transmission cycle calculated in step 100 is 0.2 sec (double cycle), and the cycle calculated in step 104 is 0.4 sec (four times cycle) exceeding the double cycle. In step 106, an affirmative determination is made, and the transmission cycle for transmitting data is determined to be 0.2 sec.

  Note that step 100 of the present transmission cycle determination processing routine is executed by the transmission cycle upper limit calculation unit 30, step 102 is executed by the communication status calculation unit 32, and steps 104 to 110 are executed by the transmission cycle calculation unit 34. Executed.

  FIG. 7 is a diagram showing the relationship between the transmission cycle determined by the transmission cycle determination unit 17, the speed of the moving body, and the communication status in the present embodiment. As shown in the figure, the X axis indicates the speed of the moving body, the Y axis indicates the communication status, and the Z axis indicates the transmission cycle. Here, the slot usage rate ξ is used as an example of the communication status. As shown in the figure, for example, when the speed of the moving body is 20 m / s, the transmission cycle for transmitting data is 0.1 sec (basic cycle) or 0.2 sec depending on the slot usage rate ξ. (Second period) is determined, but a period of 0.4 sec (third period) or more is not determined as a transmission period. As described above, the transmission cycle for transmitting data is determined according to the speed of the mobile body and the communication status so that the transmission cycle is adjusted to suppress communication traffic and the upper limit value is not exceeded.

  Further, as shown in the figure, in order to prevent chattering, it has a hysteresis characteristic with respect to the speed X of the moving body or the slot usage rate ξ. In the present embodiment, the usage condition of the communication band also has a hysteresis characteristic in the relationship between the determined transmission cycle and the usage condition of the communication band.

  As described above, according to the communication terminal device 10 according to the invention of the present embodiment, the reception situation when the transmission cycle determination unit 17 as the determination unit receives a packet by the reception circuit 12 as the reception unit. Based on the above, the transmission cycle is determined so as not to exceed the upper limit of the transmission cycle determined based on the moving distance a and the speed X of the moving body determined to transmit at least one packet during the movement of the specified distance. Therefore, at least one packet can be transmitted with a simple control and at a predetermined interval without exchanging a request packet, an information packet, a response packet, and the like between the communication terminal devices.

  Moreover, according to the communication terminal device 10 according to the invention of the present embodiment, the transmission cycle is determined based on the reception status of the packets from the peripheral communication terminal devices B, C, and D with which the communication terminal device 10 can communicate. By doing so, the peripheral terminal device in which the communication terminal device 10 and the communication terminal device 10 can communicate with each other in the area when observing the reception status of the communication terminal device 10 is determined. B, C, and D can be used as an area that does not include a hidden terminal E in which peripheral terminal devices can communicate but cannot communicate with its own communication terminal device. The transmission cycle can be determined easily.

  Further, according to communication terminal apparatus 10 according to the invention of the present embodiment, in step 102 of the transmission cycle determination processing routine, the communication status is the ratio of the number of used slots to the total number of slots in each frame. When the slot usage rate is calculated, in step 104, for example, the transmission cycle determination unit 17 as the determination unit calculates a new transmission cycle so that the new transmission cycle becomes longer as the slot usage rate becomes higher. Thus, in step 108 or step 110, it is possible to determine the transmission period so as to increase the number of empty slots while suppressing communication traffic.

  Also, according to communication terminal apparatus 10 according to the invention of the present embodiment, when the communication band usage rate, which is the communication traffic status in each frame, is calculated as the communication status in step 102 of the transmission cycle determination processing routine. In step 104, for example, according to the amount of communication traffic occurring in one cycle of the frame, the transmission cycle determination unit 17 as a determination unit can calculate a new transmission cycle, In step 110, for example, the transmission period can be determined so that the traffic within one period of the frame can be accommodated, and as a result, communication traffic is suppressed.

  In the present embodiment, the example in which the communication band usage state is calculated as the communication state by the above equation (3) has been described. However, the present invention relates to the calculation of the communication band usage state by using the above equation ( For example, the packet demodulator 14 and the communication status calculator 32 of the transmission cycle determiner 17 are connected, and the packet demodulator 14 is transmitted from the received packet. In addition to demodulating the received data, the received power of the packet is detected, so that the communication status calculation unit 32 determines the usage status of the communication band according to the following formula (4) with respect to the total received power assumed in one frame. You may make it calculate the ratio of the sum total of the reception power of the packet received within 1 frame.

As shown in FIG. 8, P _k (k = 1, 2,..., N) is the received power of the k-th packet among n packets received in one frame, and P _H is the maximum value of the received power of the packet, P _L is the minimum value of the received power of the packet, T _F is the transmission period of one frame, the T _P is the received time per one packet. The denominator of the above equation (4) indicates the sum of the assumed received power, and the numerator indicates the sum of the received power of the received packets.

  The larger the usage status of the communication band calculated by the above formula (4), the more packets with higher received power are observed, indicating that the communication bandwidth is often used. The smaller the band usage status, the less the packets with large received power are observed, indicating that the communication bandwidth is not being used much.

[Second Embodiment]
Next, the communication terminal device 40 according to the second embodiment of the present invention will be described. In addition, about the structure similar to 1st Embodiment, and the same process, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In this embodiment, the difference from the first embodiment is that in step 102 of the transmission cycle determination processing routine, in the first embodiment, the transmission cycle determination unit 17 of the communication terminal 10 has its own communication terminal. An observation area is an area that includes a peripheral communication terminal device in which the device 10 and its own communication terminal device 10 can communicate, and that does not include a hidden terminal in which the peripheral communication terminal device can communicate but the communication terminal device 10 cannot communicate. Although the example to observe was demonstrated, in this Embodiment, in step 102 of a transmission period determination processing routine, the transmission period determination part 41 of the communication terminal 40 shown in FIG. And the point which observes the area containing the communication terminal device used as a hidden terminal with respect to own communication terminal device 40 as an observation area differs.

  The observation area in this case includes, for example, peripheral communication terminal devices B, C, and D with which the communication terminal device A (communication terminal device 40) can communicate, as shown in FIG. An observation area 71 that includes a communication terminal device E that is a hidden terminal in which the device A is not communicable and does not include the communication terminal device F in which the communication terminal device A is not communicable and is not a hidden terminal is conceivable. An example will be described below. As shown in the figure, the communication area 72 in which the communication terminal A can communicate includes communication terminal devices B, C, and D, and the communication area 73 in which the communication terminal device B can communicate includes communication. The communication area 74 that includes the terminal devices A and E and can communicate with the communication terminal device C includes the communication terminal devices A and D, and the communication area 75 with which the communication terminal device D can communicate includes the communication terminal device A and C are included.

As shown in FIG. 10B, in one frame from time t ₀ to time t ₁ , communication terminal device B, communication terminal device C, and communication terminal device F use slot 1 among slots 1 to 4. Communication terminal apparatus A and communication terminal apparatus D communicate using slot 3, and communication terminal apparatus E communicates using slot 4, communication terminal apparatuses B, C, and D In each, the following frame information is generated at time t ₁ . That is, the communication terminal apparatus B receives the packet from the communication terminal apparatus A so that the data can be demodulated at the time of the slot 3, and the packet from the communication terminal apparatus E at the time of the slot 4 receives the data. When received so that it cannot be demodulated, as shown in FIG. 10 (C), “FREE” is set in the areas S1 and S2, “ACK” is set in the area S3, and “NACK” is set in the area S4. Frame information is generated. When communication terminal apparatus C detects that a packet from communication terminal apparatus A collides with a packet from communication terminal apparatus D in slot 3, as shown in FIG. 10 (C), area S1 The frame information is set so that “FREE” is set in the areas S2 and S4 and “RTC” is set in the area S3. The communication terminal apparatus D receives the packet from the communication terminal apparatus C so that the data can be demodulated when the slot is 1, and the packet from the communication terminal apparatus A is the data when the slot is the slot 3. When received in such a manner that it can be demodulated, as shown in FIG. 10C, frame information is set in which “ACK” is associated with areas S1 and S3 and “FREE” is associated with areas S2 and S4. To do.

Then, the communication terminal apparatus B, C, D between the each containing the generated frame information packets (peripheral communication terminal device) from the time t ₁ of time t _2, the the communication terminal apparatus A receives a first In step 102 of the transmission cycle determination processing routine described in the embodiment, the transmission cycle determination unit 41 of the communication terminal apparatus A observes based on frame information (other terminal frame information) demodulated and extracted from each packet. Information indicating the reception status of the peripheral communication terminal devices B, C, and D in the area 71 is created.

  FIG. 11 shows the reception status in the observation area 71 based on the reception status obtained from the peripheral communication terminals B, C, and D executed by the transmission cycle determination unit 41 in step 102 of the transmission cycle determination processing routine of the present embodiment. It is a figure which shows the flowchart of an information preparation process routine. In this embodiment, as shown in FIG. 10D, information 77 indicating the reception status of the observation area 71 is “FREE” in each of the areas S1 to S4 corresponding to the slots 1 to 4 of the frame. It is assumed that any one of “,” “ACK”, “NACK” and “RTC” is set in association with each other.

  First, in step 200, the reception status indicated by each of the areas S1 to S4 of the other terminal frame information demodulated and extracted from each received packet is examined, and whether or not there is an area where “RTC” is set. Determine.

  If a negative determination is made in step 200, the process proceeds to the next step 204. If an affirmative determination is made, in the next step 202, the slot corresponding to the region where “RTC” is set is in the observation area 71. The reception status of the observation area 71 is shown by associating the “RTC” indicating the packet collision with the area corresponding to the slot determined to have the packet collision. Information 77 is set.

  In step 202, for example, when the frame information generated by the communication terminal device C as shown in FIG. 10C is demodulated and extracted from the packet, “RTC” is set in the region S3. As shown in (D), “RTC” and the area S3 corresponding to the slot 3 are associated with each other and set in the information 77 indicating the reception status of the observation area 71.

  In step 204, the reception status indicated by each of the areas S1 to S4 of the frame information demodulated and extracted from each of the received packets is examined, and it is determined whether there is an area where “NACK” is set.

  If a negative determination is made in step 204, the process proceeds to the next step 208. If an affirmative determination is made, in step 206, which slot corresponds to the area where “NACK” is set in the observation area 71. In the peripheral communication terminal apparatus, it is determined that data demodulation has failed although a packet from another terminal is detected, and “NACK” indicating a reception failure and an area corresponding to the slot determined to have failed to be received Are set in the information 77 indicating the reception status of the observation area 71.

  In step 206, for example, when the frame information generated by the terminal B as shown in FIG. 10C is demodulated and extracted from the packet, “NACK” is set in the region S4. As shown in (), “NACK” and the area S4 corresponding to the slot 4 are associated with each other and set in the information 77 indicating the reception status of the observation area 71.

  In step 208, the reception status indicated by each of the areas S1 to S4 of the frame information demodulated and extracted from each received packet is checked to determine whether there is an area for which "ACK" is set.

  If a negative determination is made in step 208, the process proceeds to the next step 212, and if an affirmative determination is made, in the next step 210, which slot in the observation area 71 corresponds to the area where “ACK” is set. In the peripheral communication terminal device, it is determined that the packet from the other terminal has been detected and the data has been successfully demodulated, and "ACK" indicating successful reception is associated with the area corresponding to the slot that has been determined to have been successfully received. Thus, the information 77 indicating the reception status of the observation area 71 is set.

  In step 210, for example, when the frame information generated by the terminal D as shown in FIG. 10C is demodulated and extracted from the packet, since “ACK” is set in the area S1, FIG. ), The information 77 indicating the reception status of the observation area 71 is set by associating “ACK” with the area S1 corresponding to the slot 1.

  In step 212, the slot corresponding to the vacant area of the information 77 indicating the reception status of the observation area 71 determines that no packet is transmitted from other terminals in all the peripheral communication terminal devices in the observation area 71. Is associated with a corresponding area and set in information 77 indicating the reception status of the observation area 71.

  In step 212, for example, when each of the frame information generated by the terminals B, C, and D as shown in FIG. 10C is demodulated and extracted from the packet, “FREE” is used in the area S2 of all the frame information. Therefore, as shown in FIG. 10D, “FREE” is associated with the area S2 corresponding to the slot 2 and set in the information 77 indicating the reception status of the observation area 71.

  As described above, information 77 indicating the reception status of the observation area 71 can be created by the transmission cycle determination unit 17 executing the communication status information creation processing routine.

  Then, from the state indicated by each area of the information 77 indicating the reception status, the processing after the slot usage rate is calculated as the communication status by the above equation (2), the communication band usage status as the communication status is expressed by the above formula (2). Since the processing after the calculation according to 3) or the processing after the calculation of the use status of the communication band as the communication status according to the above equation (4) is the same as that in the first embodiment, the description thereof will be omitted. .

  As described above, according to the communication terminal device 40 of the invention according to the present embodiment, the transmission cycle determination unit 41 as the determination unit includes the reception included in the packet received by the reception circuit 12 as the reception unit. Based on the data indicating the situation, the upper limit of the transmission cycle determined based on the moving distance and the speed of the moving body determined to transmit at least one packet during the movement of the specified distance, or the position of the moving body Accordingly, since the transmission cycle is determined so as not to exceed the predetermined upper limit of the transmission cycle, it is possible to perform simple control without exchanging request packets, information packets, response packets, and the like between the communication terminal devices. In addition, at least one packet can be transmitted during a predetermined interval.

  Moreover, according to the communication terminal device 40 of the invention according to the present embodiment, the transmission cycle of the communication terminal device 40 of its own is determined by determining the transmission cycle based on the reception status of the peripheral communication terminal devices B, C and D. The area when observing the reception status to determine the communication terminal device 40 includes the peripheral terminal devices B, C, and D with which the communication terminal device 40 and the communication terminal device 40 can communicate, and the peripheral terminal devices B, C , D can be communicated and the area including the hidden terminal E in which the own communication terminal device 40 cannot communicate can be set, so that the transmission cycle can be determined in consideration of the existence of the hidden terminal E and the like. .

[Third embodiment]
Next, a communication terminal device 50 according to the third embodiment of the present invention will be described. In addition, about the structure similar to 1st Embodiment and 2nd Embodiment and the same process, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the first embodiment, in step 102 of the transmission cycle determination processing routine, the transmission cycle determination unit 17 of the communication terminal 10 is able to communicate with its own communication terminal device 10 and its own communication terminal device 10. An example of observing an area including only the device has been described. In the second embodiment, in step 102 of the transmission cycle determination processing routine, the transmission cycle determination unit 41 of the communication terminal 40 shown in FIG. 9 has its own communication terminal device 40, peripheral terminal device, and its own communication. The example which observed the area containing the communication terminal device used as a hidden terminal with respect to the terminal device 40 was demonstrated.

  In this embodiment, in step 102 of the transmission cycle determination processing routine, the transmission cycle determination unit 51 of the communication device terminal 50 shown in FIG. 12 can communicate with its own communication terminal device 50 and its own communication terminal device 50. Whether the observation area is an area that includes the peripheral communication terminal device and does not include the communication terminal device that is a hidden terminal for the communication terminal device 50, or the communication terminal device 50, the peripheral terminal device, and the communication terminal Whether the area including the communication terminal device that is a hidden terminal with respect to the device 50 is set as the observation area is selected according to the speed of the moving object from the vehicle speed sensor (not shown), and the first embodiment is based on the selection. Alternatively, the point of observation is different as in the second embodiment.

  Specifically, when the speed of the moving body is a predetermined value, for example, 30 km / h or higher, it is necessary to observe a wide area, so in step 102 of the transmission cycle determination processing routine, the transmission cycle determination unit 51 observes the area including the communication terminal device 50, the peripheral terminal devices B, C, and D, and the communication terminal device E that is a hidden terminal with respect to the own communication terminal device 50, as in the second embodiment. The same processing as in the second embodiment is performed. On the other hand, when the speed of the moving object is less than a predetermined value, for example, less than 30 km / h, it is not necessary to observe a wide area, so in step 102 of the transmission cycle determination processing routine, the same as in the first embodiment The first communication terminal device 50 and the peripheral communication terminal devices B, C, and D with which the communication terminal device 50 can communicate, and the area not including the hidden terminal E are observed. Processing similar to that of the form is performed.

  As a result, for example, when the speed of the mobile body on which the communication terminal device 50 is mounted is slow, such as less than a predetermined value, for example, less than 30 km / h, it is not necessary to observe the communication status in a wide area. The area for observing the situation includes the communication terminal device 50 and the peripheral communication terminal devices B, C, and D with which the communication terminal device 50 can communicate, and does not include the communication terminal device E that is a hidden terminal. The transmission cycle can be easily determined without considering other areas. In addition, when the speed of the moving body is higher than a predetermined value, for example, 30 km / h or higher, it is necessary to observe the communication status in a wide area, so communication that becomes a hidden terminal when viewed from its own communication terminal device 50 The transmission cycle can be determined in consideration of the status of the terminal device E and the like. Therefore, according to the communication terminal device 50 according to the invention of the present embodiment, the transmission cycle can be appropriately determined according to the speed of the moving body.

[Fourth Embodiment]
Next, a communication terminal device 80 according to the fourth embodiment of the present invention will be described. Note that the same reference numerals are used for the same configurations and processes as those in the first embodiment, the second embodiment, and the third embodiment (hereinafter referred to as the first embodiment). A description thereof will be omitted.

  In the first embodiment or the like, in step 100 of the transmission cycle determination processing routine, the transmission cycle upper limit determination unit 30 of the transmission cycle determination unit 17 of the communication terminal 10 or the like determines the maximum distance a or the speed of the moving object. An example in which the upper limit value of the transmission cycle is calculated using the graph (B) described above using X has been described. In this embodiment, the difference from the first embodiment or the like is that in step 100 of the transmission cycle determination processing routine, the transmission cycle upper limit value of the transmission cycle determination unit 81 of the communication terminal apparatus 80 shown in FIGS. The upper limit value of the transmission cycle calculated by 84 is associated with the position information from the navigation device 83 and stored as a past history in a storage device such as an HDD (hard disk drive) 82, and step 100 of the transmission cycle determination processing routine is performed. Thus, the transmission cycle upper limit value calculation unit 84 does not calculate the upper limit value of the transmission cycle, but uses the current position information from the navigation device 83 as a key, and the upper limit value of the transmission cycle calculated in the past corresponding to the key. Is read from the HDD 82.

  According to the communication terminal device 80 according to the invention of the present embodiment, even when the vehicle speed sensor fails, even when the information on the speed of the moving object is not available, the transmission period from the HDD 82 using the current position information as a key. The transmission period calculation unit 34 of the transmission period determination unit 81 can determine the transmission period using the read upper limit value of the transmission period. That is, according to communication terminal apparatus 80 according to the invention of the present embodiment, the transmission cycle can be determined using the upper limit value of the transmission cycle determined in advance according to the position of the moving body.

[Fifth Embodiment]
Next, a communication terminal device 90 according to the fifth embodiment of the present invention will be described. The same configuration and the same as those in the first embodiment, the second embodiment, the third embodiment, and the fourth embodiment (hereinafter referred to as the first embodiment). The processing is denoted by the same reference numerals and description thereof is omitted.

  In the first embodiment and the like, an example has been described in which the communication terminal 10 periodically transmits information by the TDMA method to communicate with other communication terminal apparatuses. In the present embodiment, the first embodiment The difference from the form and the like is that the communication terminal device 90 communicates with other communication terminal devices by periodically transmitting information by the CSMA method.

  As shown in FIG. 15, the communication terminal device 90 according to the fifth embodiment of the present invention is provided with a receiving circuit 12 that receives a packet transmitted by another communication terminal device via the receiving antenna 11. Yes. The reception circuit 12 is connected to the packet detection unit 85.

  The packet detection unit 85 detects the received packet. The packet detector 85 is connected to the packet demodulator 86.

  The packet demodulator 86 demodulates the data transmitted from the received packet and detects the received power of the packet. The packet demodulation unit 86 is connected to the information storage unit 87.

  The information storage unit 87 stores the data demodulated by the packet demodulation unit 86 and the received power value of the packet detected by the packet demodulation unit 86 for a predetermined frame. The information storage unit 87 is connected to the transmission cycle determination unit 88.

  The transmission cycle determination unit 88 is determined to transmit at least one packet during various types of information stored in the information storage unit 87, the speed of the moving body from the vehicle speed sensor (not shown), and the movement of the specified distance. Based on the travel distance (for example, 5 m), a transmission cycle is determined such that at least one packet is transmitted while the mobile body travels the travel distance. The transmission cycle determination unit 88 is connected to the packet generation unit 89. The transmission cycle determination unit 88 is connected to the transmission timing control unit 91.

  The packet generation unit 89 generates a packet, and the transmission timing control unit 91 controls the transmission timing of the packet. The packet generation unit 89 and the transmission timing control unit 91 are connected to the transmission circuit 92.

  The transmission circuit 92 transmits a packet via the transmission antenna 21.

  FIG. 16 shows a data structure of a packet transmitted and received by communication terminal apparatus 90 according to the present embodiment.

  In communication terminal apparatus 90 according to the present embodiment, a frame as a transmission cycle is periodically repeated. The communication terminal device 90 of the present embodiment detects a period in which no packet is transmitted by the peripheral communication terminal device for each frame, and transmits the packet in the detected period. One frame may be set according to the basic cycle of data transmission of each communication terminal device. For example, in order to guarantee that each communication terminal apparatus transmits a packet once every 100 ms, it may be set to 100 ms. In communication terminal device 90 according to the present embodiment, the frame is assumed to be 100 ms.

  Further, the communication terminal device 90 according to the present embodiment is capable of setting the transmission cycle to any one of the power of 2 times the frame. In this embodiment, the transmission cycle is an example. 1 time (basic period, eg 0.1 sec), 2 times (2 times period, eg 0.2 sec), 4 times (4 times period, eg 0.4 sec), 8 times (8 times) It can be set to any one of five periods (for example, 0.8 sec) and 16 times (16 times period, for example, 1.6 sec).

  The packet has header information, transmission cycle information indicating a cycle in which the packet is transmitted, and a data area including actual data to be transmitted.

  In addition, the transmission cycle information according to the present embodiment is a 3-bit area, and when the packet transmission cycle is 1 time the frame, “000” is set, and the packet transmission cycle is the frame If it is 2 times, “001” is set. If the cycle for transmitting the packet is 4 times the frame, “010” is set. If the cycle for transmitting the packet is 8 times the frame, “011” is set. When the packet transmission period is 16 times the frame, “100” is set.

  Next, the operation of communication terminal apparatus 90 according to the present embodiment when wireless communication is performed by exchanging packets with other communication terminal apparatuses (peripheral communication terminal apparatuses) will be described.

  When receiving a packet transmitted from another communication terminal device, communication terminal device 90 operates as follows.

  The packet detector 85 detects the packet received by the receiving circuit 12. The packet demodulator 86 demodulates the detected packet, restores the data sent from the other communication terminal device, and detects the received power of the packet.

  The information storage unit 87 stores the data demodulated by the packet demodulation unit 86 and the received power value of the packet detected by the packet demodulation unit 86 for a predetermined frame. In communication terminal device 90 according to the present embodiment, since the longest transmission cycle is 16 times the frame, information storage unit 87 stores data for 16 frames.

  First, the transmission cycle determination unit 88 determines a transmission cycle using the cycle of one frame as a basic cycle of packet transmission.

  The packet generation unit 89 generates a packet in which cycle information indicating the transmission cycle of the packet determined by the transmission cycle determination unit 88 is embedded in order to transmit transmission data. The transmission timing control unit 91 controls the transmission circuit 92 so as to transmit a packet at a timing corresponding to the transmission cycle determined by the transmission cycle determination unit 88. The transmission circuit 92 transmits the packet generated by the packet generation unit 89 via the transmission antenna 21 according to the control from the transmission timing control unit 91.

  In addition, when transmission of a packet is started by the transmission antenna 21, the transmission cycle determination unit 88 performs the following determination on the transmission cycle for transmitting data for each frame after the next frame.

  FIG. 17 is a diagram showing a flowchart of a transmission cycle determination processing routine for determining the transmission cycle executed by the transmission cycle determination unit 88. FIG. 18 shows the transmission cycle determination unit 88 for executing the transmission cycle determination processing routine. It is the figure represented with the functional block.

  As shown in FIG. 18, when the transmission cycle determination unit 88 that executes the transmission cycle determination processing routine is represented by a functional block, the transmission cycle upper limit value calculation unit 30 that calculates the upper limit value of the transmission cycle, A communication status calculation unit 93 that calculates a ratio (time usage rate) of time during which a packet is transmitted from the peripheral communication terminal apparatus with respect to time or a usage status of a communication band, and a transmission that determines a transmission cycle for transmitting transmission data It can be expressed by a period determining unit 94.

  The transmission cycle determination processing routine shown in FIG. 17 is executed for each frame period after the next frame when packet transmission is started by the transmission antenna 21.

  First, in step 300, the upper limit value of the transmission cycle is calculated. For example, in step 300, as shown in the graph of FIG. 19A, the communication terminal device 90 is mounted using a movement distance determined to transmit at least one packet during movement of a specified distance. The transmission period necessary for transmitting at least one packet while the mobile body travels the moving distance is calculated by the following equation (5). In the present embodiment, an example in which the maximum value of the movement distance is set to 5 m will be described.

  However, a in equation (5) is the maximum value of the moving distance, in this case, a = 5 [m], X is the speed of the moving body, and Y is the transmission period. In this embodiment, the transmission period is 0.1 sec (basic period), 0.2 sec (double period), 0.4 sec (4 times period), 0.8 sec (8 times period), and 1 sec. .6 sec (16 times period), so transmission from the velocity X of the moving body is performed by the discrete graph shown in FIG. 19B, which does not exceed the transmission cycle Y shown in the graph of FIG. Calculate the upper limit of the period. For example, as shown in the figure, when the speed X of the moving object is 25 m / s, the calculation result of the upper limit value of the transmission cycle is 0.2 sec, and when the speed X of the moving object is 10 m / s, The calculation result of the upper limit value of the transmission cycle is 0.4 sec.

In addition, the graph showing the upper limit value of the transmission period shown in FIG. 19B is the speed between v _{1 and} v ₂ and between the speeds v _{3 and} v ₄ in order to prevent chattering. Between the speeds v ₅ and v ₆ and between the speeds v _{7 and} v ₈ , there is a hysteresis characteristic with respect to the speed X of the moving body. Although details will be described later, in the relationship between the time usage rate or the communication band usage status and the determined transmission cycle, the time usage rate or the communication bandwidth usage status has hysteresis characteristics.

  In the next step 302, the communication status in each frame is calculated. For example, in step 302, the ratio of the time during which a packet is transmitted from the peripheral communication terminal device to the time of one frame (time usage rate) is calculated as the communication status by the following equation (6).

As shown in FIG. 16, _TF is the time of one frame, and _TP is the reception time per packet. The denominator of the above equation (6) indicates the time of one frame, and the numerator indicates the time during which a packet is transmitted from the peripheral communication terminal device in the time of one frame. In the present embodiment, “the number of packets transmitted from the peripheral communication terminal in one frame” shown in the above equation (6) indicates the reception status of packets in one frame in the communication terminal device 90. ing.

  As shown in the figure, as the number of packets transmitted from the peripheral communication terminal apparatus increases, the ratio of the time during which packets are transmitted from the peripheral communication terminal apparatus to the time of one frame also increases.

  In step 302, the use state of the communication band may be calculated as the communication state by the following equation (7). From the following equation (7), as the usage status of the communication band, for example, the ratio of the total received power of packets received in one frame to the total received power assumed in one frame can be obtained.

Note that, as shown in FIG. 20, P _k (k = 1, 2,..., N) is the received power of the k-th packet among n packets received in one frame, and P _H is the maximum value of the received power of the packet, P _L is the minimum value of the received power of the packet, T _F is the transmission period of one frame, the T _P is the received time per one packet. The denominator of the above equation (7) indicates the sum of the assumed received power, and the numerator indicates the sum of the received power of the received packets.

  The larger the usage state of the communication band calculated by the above equation (7), the more packets with higher received power are observed, indicating that the communication band is often used. The smaller the situation, the less the packets with large received power are observed, indicating that the communication band is not being used much. Although the ratio of received power in one frame is used as the communication status of the communication band, the present invention is not limited to this.

  In the next step 304, a new transmission cycle is calculated based on the ratio of the time during which a packet is transmitted from the peripheral communication terminal apparatus to the time of one frame calculated in step 302, or the use state of the communication band. For example, in step 304, when the ratio of the time during which packets are transmitted from the peripheral communication terminal apparatus to the time of one frame in step 302 is calculated, the calculated ratio of time is a predetermined value, for example, 40%. Is exceeded, the new transmission cycle is calculated to be longer than the current transmission cycle, for example, a cycle twice as large as the current transmission cycle is calculated as a new transmission cycle. The transmission cycle is directly calculated as a new transmission cycle. Further, when the usage status of the communication band is calculated in step 302, when the calculated usage status exceeds a predetermined value, for example, 50%, a new transmission cycle is set to be longer than the current transmission cycle. For example, a cycle that is twice the current transmission cycle is calculated as a new transmission cycle, and when it is less than 50%, the current transmission cycle is directly calculated as a new transmission cycle.

  In addition, the calculation method of the new transmission period in step 304 is not restricted to what was demonstrated above, You may make it calculate a transmission period using another method. For example, in step 304, when the ratio of the time during which a packet is transmitted from the peripheral communication terminal apparatus to the time of one frame is calculated in step 302, the calculated ratio of time is different from the above predetermined value. If the value is less than 30%, for example, a new transmission cycle is calculated so as to be shorter than the current transmission cycle, and if it is 30% or more, the current transmission cycle is directly calculated as a new transmission cycle. May be. In step 304, when the usage status of the communication band is calculated in step 302, when the calculated usage status of the communication band is a predetermined value different from the predetermined value, for example, less than 30%. May calculate a new transmission cycle so as to be shorter than the current transmission cycle, and in the case of 30% or more, the current transmission cycle may be calculated as it is as a new transmission cycle.

  In the next step 306, it is determined whether or not the transmission cycle calculated in step 304 exceeds the upper limit value of the transmission cycle calculated in step 300.

  If an affirmative determination is made in step 306, in the next step 308, the upper limit value of the transmission cycle calculated in step 300 is determined as a transmission cycle for transmitting transmission data. On the other hand, if a negative determination is made in step 306, in the next step 310, the transmission cycle calculated in step 304 is determined as a transmission cycle for transmitting transmission data. For example, the upper limit value of the transmission cycle calculated in step 300 is 0.2 sec (double cycle), and the cycle calculated in step 304 is 0.4 sec (four times cycle) exceeding the double cycle. In step 306, an affirmative determination is made, and the transmission cycle for transmitting data is determined to be 0.2 sec.

  Note that step 300 of this transmission cycle determination processing routine is executed by the transmission cycle upper limit value calculation unit 30, step 302 is executed by the communication status calculation unit 93, and steps 304 to 310 are executed by the transmission cycle calculation unit 94. Executed.

  FIG. 21 is a diagram illustrating the relationship between the transmission cycle determined by the transmission cycle determination unit 88, the speed of the moving body, and the communication status in the present embodiment. As shown in the figure, the X axis indicates the speed of the moving body, the Y axis indicates the communication status, and the Z axis indicates the transmission cycle. Here, the time usage rate α is used as an example of the communication status. As shown in the figure, for example, when the speed of the moving body is 20 m / s, the transmission cycle for transmitting data is 0.1 sec (basic cycle) or 0.2 sec depending on the time usage rate α. (Second period) is determined, but a period of 0.4 sec (third period) or more is not determined as a transmission period. Thus, the transmission cycle for transmitting data is determined so as not to exceed the upper limit value depending on the speed of the mobile body and the communication status.

  Further, as shown in the figure, in order to prevent chattering, it has a hysteresis characteristic with respect to the speed X of the moving body or the time usage rate α. In the present embodiment, the usage condition of the communication band also has a hysteresis characteristic in the relationship between the determined transmission cycle and the usage condition of the communication band.

  As described above, according to the communication terminal device 90 according to the invention of the present embodiment, the reception situation when the transmission cycle determination unit 88 as the determination unit receives the packet by the reception circuit 12 as the reception unit. Based on the above, the transmission cycle is determined so as not to exceed the upper limit of the transmission cycle determined based on the moving distance a and the speed X of the moving body determined to transmit at least one packet during the movement of the specified distance. Therefore, at least one packet can be transmitted with a simple control and at a predetermined interval without exchanging a request packet, an information packet, a response packet, and the like between the communication terminal devices.

  Further, according to communication terminal apparatus 90 according to the invention of the present embodiment, in step 302 of the transmission cycle determination processing routine, as a communication status, the time at which a packet is transmitted from the peripheral communication terminal apparatus for the time of one frame is determined. When the ratio is calculated, in step 304, for example, the transmission period determination unit 88 as the determination unit calculates a new transmission period so that the higher the ratio of the time, the longer the new transmission period becomes. Thus, at step 308 or step 310, for example, the transmission cycle can be determined so that traffic within one cycle of the frame can be accommodated.

  Further, according to the communication terminal device 90 according to the invention of the present embodiment, when the communication band usage status is calculated as the communication status in step 302 of the transmission cycle determination processing routine, in step 304, for example, Depending on the number of packets transmitted from the peripheral communication terminal device within one period of the frame, the transmission period determining unit 88 as a determining unit can calculate a new transmission period. In step 308 or 310, for example, The transmission period can be determined so as to accommodate the traffic within one period of the frame.

  In the foregoing, the first embodiment, the second embodiment, the third embodiment, the fourth embodiment, and the fifth embodiment of the present invention have been described. In these embodiments, examples of performing communication by the TDMA method or the CSMA method have been described. However, the present invention is not limited to the case of performing communication by the TDMA method or the CSMA method, and periodically transmits information. Any communication method may be used as long as the communication method communicates with other communication terminal devices.

It is the schematic which shows the 1st Embodiment of this invention. In the 1st Embodiment of this invention, it is a figure which shows the structure of the flame | frame and packet transmitted / received by the communication terminal device. In the 1st Embodiment of this invention, it is a figure which shows the flowchart of the transmission period determination processing routine for determining a transmission period. In the 1st Embodiment of this invention, it is the figure which represented the transmission cycle determination part which performs a transmission cycle determination process routine with the functional block. In the 1st Embodiment of this invention, it is a figure for demonstrating calculation of the upper limit of a transmission period. In the first embodiment of the present invention, as an observation area for observing the communication status in each frame, an area including only its own communication terminal device and a peripheral communication terminal device that can directly communicate with its own communication terminal device is observed. It is a figure for demonstrating the example made into an area. In the 1st Embodiment of this invention, it is the figure showing the relationship between the determined transmission period, the speed of a moving body, and the communication condition. In the 1st Embodiment of this invention, it is a figure which shows the received power level of the communication terminal device in 1 frame. It is the schematic which shows the 2nd Embodiment of this invention. In the second embodiment of the present invention, as an observation area for observing the communication status in each frame, a communication terminal device serving as a hidden terminal with respect to its own communication terminal device, peripheral terminal device, and its own communication terminal device. It is a figure for demonstrating the example which makes an area to include an observation area. In the 2nd Embodiment of this invention, it is a figure which shows the flowchart of a reception condition information creation process routine. It is the schematic which shows the 3rd Embodiment of this invention. It is the schematic which shows the 4th Embodiment of this invention. It is the figure which represented the transmission cycle determination part which performs the transmission cycle determination processing routine in the 4th Embodiment of this invention with the functional block. It is the schematic which shows the 5th Embodiment of this invention. In the 5th Embodiment of this invention, it is a figure which shows the reception time of the packet transmitted from the periphery communication terminal device in the structure of the flame | frame and packet transmitted / received by the communication terminal device, and the time of 1 frame. In the 5th Embodiment of this invention, it is a figure which shows the flowchart of the transmission period determination processing routine for determining a transmission period. In the 5th Embodiment of this invention, it is the figure which represented the transmission cycle determination part which performs a transmission cycle determination process routine with the functional block. In the 5th Embodiment of this invention, it is a figure for demonstrating calculation of the upper limit of a transmission period. In the 5th Embodiment of this invention, it is a figure which shows the received power level of the communication terminal device in 1 frame. In the 5th Embodiment of this invention, it is the figure showing the relationship between the transmission period determined by the transmission period determination part, the speed of a moving body, and the communication condition.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Communication terminal device 11 Reception antenna 12 Reception circuit 13 Packet detection part 14 Packet demodulation part 15 Frame information generation part 16 Information storage part 17 Transmission period determination part 18 Packet generation part 19 Transmission timing control part 20 Transmission circuit 21 Transmission antenna

Claims (5)

A communication terminal device mounted on a mobile body,
Receiving means for receiving packets transmitted at a predetermined cycle from the peripheral communication terminal device;
A transmission period determined based on a moving distance determined to transmit at least one packet during movement of a specified distance and a speed of the moving body based on a reception situation when the packet is received by the receiving means; Determining means for determining a transmission cycle so as not to exceed an upper limit value or a predetermined upper limit value of the transmission cycle according to the position of the moving body;
Transmitting means for transmitting a packet at the transmission period determined by the determining means;
Including a communication terminal device. A communication terminal device mounted on a mobile body,
Receiving means for receiving a packet including data indicating a reception status when the peripheral communication terminal apparatus receives a packet, which is transmitted at a predetermined period from the peripheral communication terminal apparatus;
Based on the movement distance determined to transmit at least one packet during the movement of the specified distance based on the data indicating the reception status included in the packet received by the reception means, and the speed of the moving body Determining means for determining a transmission cycle so as not to exceed an upper limit value of a transmission cycle determined in advance or an upper limit value of a transmission cycle determined in advance according to the position of the mobile body;
Transmitting means for transmitting a packet including data indicating a reception status when the packet is received at the transmission cycle determined by the determining means;
Including a communication terminal device.   The communication terminal apparatus according to claim 1, wherein the reception unit receives a packet transmitted from a peripheral communication terminal apparatus in a slot unit in which each frame repeated at a predetermined period is time-divided.   The reception means is a packet including data indicating a reception status when each frame repeated at a predetermined cycle is transmitted from the peripheral communication terminal device in a time-divided slot unit and the peripheral communication terminal device receives the packet. The communication terminal device according to claim 2, which receives   The determination means has a transmission cycle determined according to a ratio of the number of used slots to a total number of slots in each of the frames, or a transmission cycle determined according to a use state of a communication band in each of the frames. The communication terminal device according to claim 3 or 4, wherein when the upper limit value of the cycle is exceeded, the upper limit value is determined as a transmission cycle.

Images