JP2015146563A - Communication device, communication system, and communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a communication device capable of suppressing packet collision in a plurality of mobile bodies existing therearound, a communication system, and a communication method.SOLUTION: A communication device 1 is installed in a mobile body, and comprises: position detection means 10 for detecting the position of the mobile body; packet communication means 20 for transmitting and receiving transmission and reception packets including traffic information indicating the amount of reception between itself and other mobile bodies; storage means 20 for storing a table indicating the relationship between the position of the mobile body and the transmission timing of a transmission packet; decision means 40 for deciding a transmission timing candidate of the transmission packet on the basis of the position of the mobile body detected by the position detection means 10 and the table stored in the storage means 30; and determination means 50 for determining whether to use the transmission timing candidate decided by the decision means 40 as a final transmission timing on the basis of the traffic information.

Description

  The present invention relates to a communication device, a communication system, and a communication method.

  As a communication device, when transmitting and receiving a packet between moving bodies such as a passenger car, a large vehicle, a two-wheeled vehicle, a bicycle, or a pedestrian, a technique for controlling a transmission timing for transmitting the packet has been conventionally proposed. Patent Literature 1 discloses an inter-vehicle communication system in which packets between vehicles are communicated via a relay. In this prior art, the transmission timing of packets transmitted from each vehicle toward the repeater is determined based on the traveling direction of the vehicle, the position of the vehicle, or the like. In this way, Patent Literature 1 attempts to improve the probability that a relay receives a packet transmitted from each vehicle by suppressing collision of packets transmitted from each vehicle.

  Patent Document 2 discloses a communication terminal that receives information broadcast from a transmission source and broadcasts the information to other terminals. In Patent Document 2, the transmission timing for broadcasting received information is determined based on the position of the transmission source and the current position of the terminal itself. This conventional technique thereby avoids collision of information transmitted from a communication terminal and attempts to improve information reception performance at other terminals.

JP 2008-92197 A (Claim 1, Claim 2) Japanese Patent Laying-Open No. 2005-86643 (Claim 1)

  However, the inter-vehicle communication system disclosed in Patent Document 1 is intended to improve the packet reception probability in the repeater, and no consideration is given to the reception of packets in all mobile terminals. Further, the communication terminal disclosed in Patent Document 2 controls transmission timing based on positional information between the transmission source and the own terminal, and there are terminals in the vicinity in addition to the transmission source and the own terminal. In this case, there is a risk of collision with information transmitted from the peripheral terminals.

  The present invention has been made against the background of the above problems, and provides a communication device, a communication system, and a communication method for suppressing packet collisions in a plurality of mobile objects existing in the vicinity.

  The communication apparatus according to the present invention is a communication apparatus mounted on a mobile body, and includes traffic information indicating a received amount between a position detection unit that detects the position of the mobile body and another mobile body. Packet communication means for transmitting and receiving transmission packets and reception packets, storage means for storing a table indicating the relationship between the position of the mobile body and the transmission timing of the transmission packet, the position of the mobile body detected by the position detection means, and storage Determining means for determining a transmission timing candidate of the transmission packet based on the table stored in the means, and whether to determine the transmission timing candidate determined by the determining means as the final transmission timing based on the traffic information Determining means for determining.

  According to the present invention, since the transmission timing is controlled based on the position of the mobile unit and the traffic information, it is possible to suppress collision of packets in a plurality of mobile units existing in the vicinity.

1 is a block diagram showing a communication device 1 according to a first embodiment. FIG. 3 is a diagram showing a table in the first embodiment. 6 is a diagram illustrating transmission timing in the first embodiment. FIG. FIG. 3 is a diagram showing a table in the first embodiment. 3 is a flowchart showing an operation of the communication apparatus 1 according to the first embodiment.

  Hereinafter, embodiments of a communication device, a communication system, and a communication method according to the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments described below. Moreover, in the following drawings including FIG. 1, the relationship of the size of each component may be different from the actual one.

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a communication device 1 according to the first embodiment. The communication device 1 will be described with reference to FIG. As shown in FIG. 1, the communication device 1 is mounted on a mobile body, and includes a position detection unit 10, a packet communication unit 20, a storage unit 30, a determination unit 40, and a determination unit 50. ing.

(Position detection means 10)
The position detection means 10 detects the position of the moving body. The position detecting means 10 is, for example, a GPS receiver, and detects the position of the mounted moving body by being mounted on the moving body.

(Packet communication means 20)
The packet communication means 20 transmits / receives a transmission packet and a reception packet including traffic information indicating a reception amount to / from another mobile body. The packet communication unit 20 includes a packet transmission unit 21 and a transmission antenna 22, and a reception antenna 23 and a packet reception unit 24.

(Packet transmitting means 21, transmitting antenna 22)
The packet transmission unit 21 generates a transmission packet by performing modulation or the like on a packet transmitted to another mobile unit. The transmission antenna 22 transmits the transmission packet generated by the packet transmission means 21 to another mobile unit.

(Receiving antenna 23, packet receiving means 24)
The receiving antenna 23 receives a packet transmitted from another mobile unit. The packet receiver 24 demodulates the packet received by the receiving antenna 23 to generate a received packet.

(Storage means 30)
The storage means 30 stores a table indicating the relationship between the position of the moving body and the transmission timing of the transmission packet. FIG. 2 shows a table in the first embodiment. As shown in FIG. 2, the table is divided into a plurality of areas for each range in which transmitted packets reach. And the 1st transmission timing of the packet corresponding to a 1st area | region differs from the 2nd transmission timing of the packet corresponding to the 2nd area | region adjacent to a 1st area | region. FIG. 2 illustrates a case where there are nine types of transmission timings, and each of the belonging areas i = 1 to 9 is illustrated. For example, when the affiliation area i = 7 is selected, a region CR from which a packet arrives is a hatched region in FIG. As described above, the area adjacent to the belonging area i = 1 is the belonging area i = 2 to 9, which is different from the belonging area i = 1. In this way, the generation of hidden terminals is prevented by dividing the area so that the belonging areas i to which the same transmission timing is applied do not overlap.

  In the first embodiment, a table in which the area is divided by a quadrangle is illustrated, but the area may be a triangle or a hexagon, or may be another shape. Moreover, each area | region does not need to be provided with the same shape, A shape may differ for every area | region. Depending on the shape and size of the area to be adopted, the transmission timing occupation time, the occurrence rate of hidden terminals, and the like vary, and the amount of data that can be transmitted and the packet reception performance vary.

(Determination means 40)
The determination unit 40 determines transmission timing candidates of transmission packets based on the position of the moving body detected by the position detection unit 10 and the table stored in the storage unit 30. As shown in FIG. 1, the determining unit 40 includes a position information specifying unit 41 and a transmission timing candidate determining unit 42.

(Position information specifying means 41)
The position information specifying unit 41 specifies the position of the moving body in the table based on the position of the moving body detected by the position detecting unit 10 and the table stored in the storage unit 30. Specifically, it is specified which position of the detected moving body matches the position of the table shown in FIG.

(Transmission timing candidate determination means 42)
The transmission timing candidate determination unit 42 determines transmission timing candidates based on the position of the moving body in the table specified by the position information specifying unit 41. Specifically, in the table, the transmission timing corresponding to the belonging area i of the area that matches the position of the moving object is set as a transmission timing candidate. For example, when the area that matches the position of the moving object is the belonging area i = 1, the transmission timing candidate Si = S1. FIG. 3 is a diagram illustrating transmission timing in the first embodiment. When the transmission timing is divided into nine parts 1 to 9 as in FIG. 2, the transmission timings are shifted in the order 1 to 9 starting from the reference timing as shown in FIG. 3.

  In the first embodiment, the reference timings generated at regular intervals are equally divided into nine equal intervals, and the transmission timings are respectively applied. However, the intervals need not be equal intervals. In addition, transmission timing assignment may be changed for each region where a mobile object exists. In this case, information regarding transmission timing assignment is added to the table.

(Determination means 50)
The determination unit 50 determines whether or not to determine the transmission timing candidate Si determined by the determination unit 40 as the final transmission timing based on the traffic information included in the received packet received by the packet communication unit 20. is there. As shown in FIG. 1, the determination unit 50 includes a first determination unit 60, a change unit 70, and a second determination unit 80.

(First determination means 60)
The first determination means 60 performs primary determination on whether or not to determine the transmission timing candidate Si as the final transmission timing based on the traffic information. As shown in FIG. 1, the first determination unit 60 includes a first traffic generation unit 61, a first threshold processing unit 62, and a first final transmission timing determination unit 63.

(First traffic generation means 61)
The first traffic generation means 61 counts the amount of received packets received by the packet communication means 20, and generates first traffic information based on the amount of the received packets and the transmission timing candidate Si. It is. The first traffic information Ti is communication traffic received by the mobile body during the transmission timing candidate Si. This is because the communication traffic Ti ′ obtained by counting the amount of packets received by the packet communication means 20 during each transmission timing Si ′, that is, during the period P ₁ in FIG. 3, and the transmission timing candidate Si. To be determined. That is, Ti ′ when i ′ = i is Ti.

(First threshold processing means 62)
The first threshold processing unit 62 determines whether or not the first traffic information Ti generated by the first traffic generation unit 61 is equal to or higher than a predetermined first traffic threshold V0. .

(First final transmission timing determination means 63)
The first final transmission timing determining unit 63 determines the transmission timing candidate Si as the final transmission timing when the first threshold processing unit 62 determines that the first traffic information Ti is less than the first traffic threshold V0. Is to be determined. In this case, this transmission timing candidate Si is transmitted to the packet communication means 20, and a packet is transmitted from the transmission antenna 22 with this transmission timing candidate Si.

  In addition, the first final transmission timing determination unit 63 determines that the first threshold information processing unit 62 determines that the first traffic information Ti is greater than or equal to the first traffic threshold value V0. Is not determined as the final transmission timing. In this case, information that the transmission timing candidate Si is not determined as the final transmission timing is transmitted to the changing unit 70.

(Change means 70)
When the first determination unit 60 determines that the transmission timing candidate Si has not been determined as the final transmission timing, the changing unit 70 changes the transmission timing candidate Si to the transmission timing second candidate Sj. Specifically, the changing means 70 first calculates the selection probability α for each transmission timing Si ′ based on the communication traffic Ti ′. For example, the selection probability α is calculated by the following equation (1).

  α = (1 / Ti ′) / Σ (1 / Ti ′) (1)

  In Expression (1), the selection probability α at the transmission timing Si ′ where the communication traffic Ti ′ is large is low. After the selection probability α is calculated, the transmission timing second candidate Sj is randomly selected so as to be proportional to the selection probability α.

(Second determination means 80)
The second determination means 80 is a secondary determination for determining whether or not to determine the transmission timing second candidate Sj changed by the changing means 70 as the final transmission timing based on the traffic information. As shown in FIG. 1, the second determination unit 80 includes a second traffic generation unit 81, a second threshold processing unit 82, and a second final transmission timing determination unit 83.

(Second traffic generating means 81)
The second traffic generation means 81 is based on the other terminal traffic information in the other mobile unit included in the received packet received by the packet communication means 20 and the reception timing at which the received packet is received by the packet communication means 20. The second traffic information is generated. The other terminal traffic information is received by the transmission source m, which is another mobile unit, during the transmission timing Sj ′. A matrix Uj′k (m) is generated from the other terminal traffic information and the information related to the reception timing Sk at which the received packet is received by the packet communication means 20.

  Based on this matrix Uj′k (m), the representative of the communication traffic received by the mobile unit belonging to the surrounding mobile unit k at the transmission timing Sk ′ during the transmission timing Sj ′. Second traffic information Tjk ′, which is a value, is calculated. Specifically, a matrix Uj′k (m) where j ′ = j is extracted and divided for each transmission timing Sk ′, and for each k ′, the maximum of Ujk ′ (m) A value or an average value can be used as the representative value Tjk ′.

  In addition, the second traffic generation means 81 extracts received data necessary for terminal control from the received packet received by the packet communication means 20.

(Second threshold processing means 82)
The second threshold value processing unit 82 determines whether or not the second traffic information Tjk ′ generated by the second traffic generation unit 81 is equal to or greater than a predetermined second traffic threshold value. . The second traffic threshold value Vi′j′k ′ is calculated using the preset traffic threshold value V0 ′. The second threshold value processing unit 82 uses the second traffic information Tjk ′ and the second traffic information value Tjk ′. The second traffic threshold Vi′j′k ′ is compared. Specifically, Vijk ′ satisfying i ′ = i and j ′ = j is extracted from the second traffic threshold value Vi′j′k ′, which is a matrix, and the second traffic for each k ′. The information Tjk ′ is compared with the extracted Vijk ′.

(Second final transmission timing determination means 83)
The second final transmission timing determining unit 83 determines the transmission timing when the second threshold processing unit 82 determines that the second traffic information Tjk ′ is less than the second traffic threshold Vi′j′k ′. The second candidate Sj is determined as the final transmission timing. In this case, this transmission timing second candidate Sj is transmitted to the packet communication means 20, and a packet is transmitted from the transmission antenna 22 at this transmission timing second candidate Sj. Specifically, when all the second traffic information Tjk ′ is smaller than Vijk ′, the transmission timing second candidate Sj is determined as the final transmission timing.

  In addition, the second final transmission timing determination unit 83 determines that the second traffic information Tjk ′ is greater than or equal to the second traffic threshold Vi′j′k ′ by the second threshold processing unit 82. In this case, the transmission timing second candidate Sj is not determined as the final transmission timing, and the transmission timing second candidate Sj is changed by the changing means 70. Specifically, when at least one second traffic information Tjk ′ is greater than or equal to Vijk ′, the transmission timing second candidate Sj is not determined as the final transmission timing, and the transmission timing second candidate Sj is changed again. Changed by means 70. When at least one second traffic information Tjk ′ is greater than or equal to Vijk ′, the transmission timing candidate Si before being changed to the transmission timing second candidate Sj may be used as the final transmission timing.

  Here, the second traffic threshold value Vi′j′k ′ used for determining the transmission timing of the belonging area i ′, that is, the communication received by the mobile body at the transmission timing Sk ′ during the transmission timing Sj ′. A traffic threshold for traffic will be described. In FIG. 2, in a peripheral area centered at i = 1, packets transmitted from the belonging area of j ′ = 9 (right next to 1) are k ′ = 1, 2 (upper right of 1), 7 ( 1 (right next to 1), 9 (right next to 1), 3 (next to the lower right of 1), and 8 (next to the lower right of 1) belong directly to the packet. For this reason, if no packet is transmitted from another terminal at the transmission timing S9, the communication traffic received during the transmission timing S9 in these belonging areas is equal in any belonging area.

  On the other hand, in FIG. 2, in the peripheral region centered at i = 1, packets transmitted from the belonging area of j ′ = 9 (right next to 1) are k ′ = 4 (next upper left of 1), 6 ( The packet does not reach the affiliation area of 5 (left adjacent to 1) and 5 (next to the lower left of 1). Therefore, if no packet is transmitted from another terminal at the transmission timing S9, the communication traffic received during the transmission timing S9 in these belonging areas is 0 in any belonging area.

  If there is an belonging area with a large communication traffic that is out of the above state, a hidden terminal relationship may occur if the final transmission timing is S9. FIG. 4 is a diagram showing a table in the first embodiment. As described above, in the first embodiment, as shown in FIG. 4, the second traffic threshold V19k ′ when i = 1 and j ′ = 9 is k ′ = 1, 2, 7, 9, 3, In the case of 8, V19k ′ = T9 + V0 ′. When k '= 4, 6, 5, V19k' = V0 '. In other cases, that is, the second traffic threshold Vi′j′k ′ in j ′ = 2 to 8 can be calculated in the same manner as described above.

  In addition, the communication apparatus 1 further includes a traffic information adding unit 90 and a reference timing determining unit 91.

(Traffic information adding means 90)
The traffic information adding means 90 adds the communication traffic Ti ′ generated by the first traffic generating means 61 to the transmission data necessary for control of other terminals, and transmits the transmission data to which the communication traffic Ti ′ is added as a packet. The data is transmitted to the transmission means 21. As a result, the other terminal that has received the transmission data can acquire information called communication traffic Ti ′. As described above, the transmission data and the communication traffic Ti ′ may be transmitted in the same packet, or the transmission data and the communication traffic Ti ′ may be transmitted in different packets. Good. In this case, the matrix Uj′k (m) corresponding to the communication traffic Ti ′ and the received data are extracted from different packets.

(Reference timing determination means 91)
The reference timing determination unit 91 determines a reference timing that serves as a reference when determining the transmission timing, and transmits the determined reference timing to the packet transmission unit 21. As described above, the reference timing is a starting point of transmission timing as shown in FIG. The reference timing is determined based on the timing at which the reference signal is received by the position detection unit 10 such as a GPS receiver, but is not limited thereto.

  Next, a communication method of the communication device 1 according to the first embodiment will be described. FIG. 5 is a flowchart showing the operation of the communication apparatus 1 according to the first embodiment. As shown in FIG. 5, first, the position of the moving body is detected by the position detecting means 10, and information on the position of the moving body is transmitted to the position information specifying means 41 (step S1).

  Next, the position information specifying unit 41 specifies the position of the moving body in the table based on the position of the moving body and the table stored in the storage unit 30, and this is transmitted to the transmission timing candidate determining unit 42. (Step S2). Then, the transmission timing candidate determining means 42 determines the transmission timing candidate Si based on the position of the moving body in the table specified by the position information specifying means 41, which is the first final transmission timing determining means 63 and the first transmission timing determining means 63. Is transmitted to the first traffic generation means 61 (step S3).

  On the other hand, the first traffic generation means 61 counts the amount of received packets received by the packet communication means 20, and generates first traffic information Ti based on the amount of received packets and the transmission timing candidate Si. Then, the first traffic information Ti is transmitted to the first threshold processing means 62 (step S4). At that time, the communication traffic Ti ′ generated by the first traffic generation unit 61 is transmitted to the traffic information addition unit 90. Then, the first threshold processing unit 62 determines whether or not the first traffic information Ti generated by the first traffic generation unit 61 is equal to or greater than a predetermined first traffic threshold V0. (Step S5).

  In step S5, when the first threshold value processing means 62 determines that the first traffic information Ti is less than the first traffic threshold value V0 (No in step S5), the first final transmission timing determination means 63. Thus, the transmission timing candidate Si is determined as the final transmission timing (step S14). On the other hand, if the first threshold value processing means 62 determines that the first traffic information Ti is equal to or greater than the first traffic threshold value V0 in step S5 (Yes in step S5), the first final transmission timing determination The transmission timing candidate Si is not determined as the final transmission timing by the means 63, and this information is transmitted to the changing means 70.

  Here, the counter n of the number of changes of the transmission timing candidate Si in the changing means 70 is reset to 0 (step S6). Thereafter, the transmission means candidate Si is changed to the transmission timing second candidate Sj by the changing means 70, and this transmission timing second candidate Sj is transmitted to the second final transmission timing determining means 83 (step S7).

  On the other hand, the other traffic generation information received by the transmission source m during the transmission timing Sj ′ by the second traffic generation means 81 and the information related to the reception timing Sk at which the received packet is received by the packet communication means 20 are a matrix. Uj′k (m) is generated (step S8). Further, the second traffic generation means 81 determines that the mobile area belonging to the surrounding mobile body of k, that is, the transmission timing Sk ′ of the surrounding mobile bodies is the transmission timing Sj ′ based on the matrix Uj′k (m). Second traffic information Tjk ′, which is a representative value of communication traffic received in the meantime, is calculated, and this second traffic information Tjk ′ is transmitted to the second threshold processing means 82 (step S9).

  Then, the second traffic threshold value calculated by the second threshold value processing unit 82 using the traffic threshold value V0 ′ set in advance by the second traffic information Tjk ′ generated by the second traffic generation unit 81 is used. It is determined whether or not Vi′j′k ′ or more (step S10). In this step S10, when the second threshold value processing means 82 determines that all the second traffic information Tjk ′ is less than the second traffic threshold value Vi′j′k ′ (No in step S10). The second final transmission timing determination means 83 determines the second transmission timing candidate Sj as the final transmission timing (step S11).

  On the other hand, when the second threshold value processing means 82 determines in step S10 that at least one second traffic information Tjk ′ is equal to or greater than the second traffic threshold value Vi′j′k ′ (in step S10). Yes), the second final transmission timing determination means 83 does not determine the second transmission timing candidate Sj as the final transmission timing, and the process proceeds to step S12.

  In step S12, 1 is added to the counter n of the number of changes of the transmission timing candidate Si in the changing means 70. Then, it is determined whether or not the counter n is equal to or greater than a preset N0 (step S13). If it is determined in step S13 that n is equal to or greater than N0 (Yes in step S13), the process proceeds to step S14, and the transmission timing candidate Si before being changed to the transmission timing second candidate Sj is determined as the final transmission timing. Is done. On the other hand, when it is determined in step S13 that n is less than N0 (No in step S13), the process returns to step S7, and the transmission timing second candidate Sj is changed again by the changing unit 70. If N0 is set to 1, the transmission timing second candidate Sj is not changed again.

  As described above, since the communication device 1 controls the transmission timing based on the position of the mobile body and the traffic information, the communication apparatus 1 can set the transmission timing with good communication efficiency, and a plurality of mobile bodies existing in the vicinity. Can prevent packet collisions. Thereby, the reception probability of a packet when all the moving bodies are subject to reception is improved.

  The communication device 1 according to the first embodiment first attempts to transmit a packet at a transmission timing based on the position information, thereby avoiding a packet collision caused by a hidden terminal. In addition to this, the communication apparatus 1 according to the first embodiment further changes the transmission timing based on the position information and the traffic information. For this reason, even if the number of mobile bodies existing in the vicinity increases, the probability that the mobile bodies transmit at the same transmission timing is drastically reduced, so that collision of transmitted packets can be suppressed.

  Further, in the changing means 70, the transmission timing second candidate Sj is randomly selected so as to be proportional to the calculated selection probability α, and is not uniquely selected. For this reason, it is suppressed that the surrounding mobile bodies change all at the same transmission timing. Furthermore, in the first embodiment, the transmission timing is changed after estimating that the collision of packets by the hidden terminal is unlikely to occur. For this reason, it is possible to avoid collision of transmitted packets.

  The communication device 1 according to Embodiment 1 is mounted on, for example, a moving body. And the communication system in which transmission / reception of a packet is performed between the mobile bodies on which the communication device 1 is mounted is configured. Thus, in the communication system having a plurality of mobile units including the communication device 1 according to the first embodiment, the collision of packets transmitted from the mobile unit can be avoided as described above. The mobile body on which 1 is mounted can accurately grasp the presence of other mobile bodies present in the vicinity. For this reason, the collision between moving bodies is suppressed.

  DESCRIPTION OF SYMBOLS 1 Communication apparatus, 10 Position detection means, 20 Packet communication means, 21 Packet transmission means, 22 Transmission antenna, 23 Reception antenna, 24 Packet reception means, 30 Storage means, 40 Determination means, 41 Position information specification means, 42 Transmission timing candidate Determination means, 50 determination means, 60 first determination means, 61 first traffic generation means, 62 first threshold processing means, 63 first final transmission timing determination means, 70 change means, 80 second determination means 81 Second traffic generating means, 82 Second threshold processing means, 83 Second final transmission timing determining means, 90 Traffic information adding means, 91 Reference timing determining means

Claims (8)

A communication device mounted on a mobile body,
Position detecting means for detecting the position of the moving body;
Packet communication means for transmitting / receiving a transmission packet and a reception packet including traffic information indicating a reception amount with another mobile unit;
Storage means for storing a table indicating a relationship between the position of the mobile body and the transmission timing of the transmission packet;
Determining means for determining a transmission timing candidate of the transmission packet based on the position of the moving body detected by the position detecting means and the table stored in the storage means;
And a determination unit that determines whether or not the transmission timing candidate determined by the determination unit is determined as a final transmission timing based on the traffic information. The determination means includes
First determination means for primarily determining whether or not to determine the transmission timing candidate as a final transmission timing based on the traffic information;
Changing means for changing the transmission timing candidate to a transmission timing second candidate when the first determination means determines that the transmission timing candidate has not been determined as the final transmission timing;
And a second determination unit that secondarily determines whether or not the second transmission timing candidate changed by the changing unit is determined as a final transmission timing based on the traffic information. The communication apparatus according to 1. The first determination means includes
First traffic generation means for counting the amount of received packets received by the packet communication means and generating first traffic information based on the amount of received packets and the transmission timing candidates;
First threshold value processing means for determining whether or not the first traffic information generated by the first traffic generation means is greater than or equal to a predetermined first traffic threshold value;
When the first threshold processing means determines that the first traffic information is less than the first traffic threshold, the transmission timing candidate is determined as a final transmission timing, and the first traffic information is And a first final transmission timing determination unit that does not determine the transmission timing candidate as a final transmission timing when the first threshold processing unit determines that the first traffic threshold is equal to or greater than the first traffic threshold. The communication device according to claim 2. The second determination means includes
Second traffic information is generated based on other terminal traffic information in another mobile unit included in the received packet received by the packet communication means and a reception timing at which the received packet is received by the packet communication means. A second traffic generation means;
Second threshold value processing means for determining whether the second traffic information generated by the second traffic generation means is greater than or equal to a predetermined second traffic threshold value;
When the second threshold processing means determines that the second traffic information is less than the second traffic threshold, the transmission timing second candidate is determined as a final transmission timing, and the second traffic When the second threshold processing means determines that the information is equal to or greater than the second traffic threshold, the transmission timing second candidate is not determined as the final transmission timing, and the transmission timing second candidate is changed. The communication apparatus according to claim 2, further comprising: a second final transmission timing determination unit that is changed by the unit. The determining means includes
Position information specifying means for specifying the position of the moving body in the table based on the position of the moving body detected by the position detecting means and the table stored in the storage means;
The transmission timing candidate determining means for determining the transmission timing candidate based on the position of the mobile body in the table specified by the position information specifying means. Item 1. The communication device according to item 1. The table is
The transmission packet is divided into a plurality of areas within a range in which the packet arrives, the first transmission timing of the packet corresponding to the first area, and the first of the packets corresponding to the second area adjacent to the first area The communication apparatus according to claim 1, wherein the transmission timing is different from the transmission timing of 2. It has a some mobile body provided with the communication apparatus of any one of Claims 1-6. The communication system characterized by the above-mentioned. Detecting the position of the moving object;
Determining a packet transmission timing candidate based on a table indicating a relationship between the position of the mobile object and the transmission timing of the packet, and the detected position of the mobile object;
A step of determining whether or not the transmission timing candidate is set as a final transmission timing based on traffic information included in a received packet received by the mobile unit.

Images