JP2009071468A - Communicating method and apparatus in packet communication - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication method and apparatus in packet communication, which reduces transmission waiting time, also reduces a collision probability, and achieves improvement of throughput even if there is a collision forecast error under a collision forecast regarding the communication method and apparatus in the packet communication. <P>SOLUTION: The method is composed of: determining a transmission waiting period for packet transmission and a probability of transmission by transmission timing candidates in the respective possible period of the transmission waiting; determining whether transmission is available, based on the transmission probability of the respective transmission timing candidates; when own transmission or transmission from others is not detected even if the transmission timing candidates pass in the transmission waiting period which has been determined beforehand, determining again the transmission waiting period and the transmission probability, or the transmission probability; and determining whether transmission is available based on the transmission probability by the respective transmission timing candidates. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a communication method and apparatus in packet communication, and more specifically, in each wireless apparatus using a medium access control system having a collision avoidance function such as CSMA-CA (Carrier Sense Multiple Access with Collision Avidance). The present invention relates to a communication method and apparatus in packet communication for reducing the collision probability of data transmitted by the apparatus.

  In CSMA-CA communication, for example, in the infrastructure mode with a base unit such as a wireless LAN, after performing carrier sense, a transmission request is made with a short packet. Therefore, the influence of throughput can be reduced. In addition, since there is no normal reception response from the master unit, a collision is known, and the contention window can be controlled based on the collision, so that the number of contention windows can be optimized. Here, the contention window is the collision window size, and the collision window size waits for transmission prior to transmission of the generated packet in order to avoid collision with a packet of another communication device. The number of slots. If a carrier wave (carrier) transmitted by another wireless communication terminal is detected during this time, a predetermined collision avoidance procedure is executed in accordance with the transmission of the packet.

  On the other hand, in the case of broadcast communication, if a transmission request is made with a short packet as in the infrastructure mode, there will be a large number of communication partners, so the traffic of normal reception responses will increase and affect the transmission of the original data. In addition, there is little effect because the communication partner normally receives or collides. Therefore, after carrier sense, without making a transmission request, when the number of slots in a contention window of a certain size is randomly selected and data transmission is performed, if a collision occurs, this is a collision of a data packet with a large data size , The impact on throughput will be greater.

  In addition, since the contention window cannot be optimized, packet collisions are likely to occur, and when a collision is to be avoided, the contention window becomes large, which increases the time during which no one is transmitting.

  In this type of conventional system, a collision is predicted for a certain period before transmission, and a small-sized contention window is selected with a small probability and a large-sized contention window is selected with a large probability according to the predicted value. A method is considered (see, for example, Patent Document 1).

Further, in an access control method in a system in which an access point communicates with one or more terminals via a wireless network, the terminal having a data packet to be transmitted as a contention period randomly derives a contention window, A first step of transmitting the contention window to the access point, and as a contention-free period, the access point registers the received contention window for each terminal, and from the terminal having a small contention window A technique having a second step of sequentially transmitting polling is known (see, for example, Patent Document 2).
Japanese Patent Laying-Open No. 2005-286601 (paragraphs 0046 to 0052, FIGS. 1, 2, and 5) Japanese Patent Laying-Open No. 2006-108966 (paragraphs 0041 to 0053, FIGS. 4A and 4B)

  For example, in the case of Patent Document 1, since the probability of selecting a contention window having a small size is small, the time during which no one is transmitting (transmission waiting time) increases on average. In addition, since the transmission probability is increased sequentially, there is a problem that many communication devices transmit a packet and cause a collision when the transmission probability becomes larger than the optimal probability.

  The present invention has been made in view of such a problem. Under the collision prediction, even if there is a collision prediction error, the transmission waiting time is reduced, the collision probability is reduced, and the throughput is improved. It is an object of the present invention to provide a communication method and apparatus in packet communication capable of achieving the above.

  (1) According to the first aspect of the present invention, in a communication apparatus that performs packet transmission, a transmission waiting time period and a transmission probability candidate within each transmission waiting time period are determined, and each transmission timing candidate is determined. The transmission is determined based on the transmission probability, and if it is transmitted by itself or no other transmission is detected even after the predetermined transmission waiting period has elapsed, the transmission waiting period and the transmission are again transmitted. Probability or transmission probability is determined, and whether transmission is possible or not is determined based on the transmission probability at each transmission timing candidate.

(2) The invention described in claim 2 is characterized in that a transmission waiting-enabled period or the maximum value of the number of transmission timing candidates is determined, and transmission is performed with a probability of 1 when it becomes the last transmission timing candidate.
(3) The invention according to claim 3 is characterized in that the transmission probability is corrected so as to increase the transmission probability.

(4) The invention according to claim 4 is characterized in that, when a predetermined transmission waiting period is reached, the transmission waiting period and the transmission probability, or only the transmission probability is corrected.
(5) In the communication device that performs packet transmission, the invention according to claim 5 is a probability determination means for determining a probability of transmission with a transmission waiting time period and a transmission timing candidate within each transmission standby time period, and each transmission Transmission possibility determining means for determining whether transmission is possible or not based on transmission probability with respect to timing candidates, even if a predetermined number of transmission standby periods have elapsed, transmission by itself or other transmission is not detected The transmission waiting possibility period and the transmission probability, or a determination means for determining the transmission probability, and the transmission availability determination means determines whether or not transmission is possible based on the transmission probability at each transmission timing candidate. It was made to do.

  (6) The present invention is characterized in that when a predetermined transmission waiting period is reached, only the transmission standby period and the transmission probability, or only the transmission probability are corrected with a predetermined probability.

  (7) Further, in the present invention, when a predetermined transmission standby period is reached, the transmission standby period and the transmission probability, or the correction timing of only the transmission probability is distributed.

  (8) Also, in the present invention, when another communication apparatus performs transmission and transmission is not possible, only the next transmission waiting period and the transmission probability, or only the transmission probability is the same as when the other communication apparatus transmits. It is characterized by using a value.

  (9) In the present invention, when another communication apparatus performs transmission and transmission is not possible, the next transmission standby period and the transmission probability, or only the transmission probability is based on the previous first predicted value. It is characterized by using possible period and transmission probability.

  (10) Further, in the present invention, when another communication apparatus performs transmission and transmission is not possible, the next transmission standby period and transmission probability, or only the transmission probability is a transmission standby period reflecting the previous transition. It is characterized by using transmission probability. (11) Further, in the present invention, the packet reception period for estimating the transmission waiting communication apparatus is a period from the previous packet transmission to the next transmission. (12) Further, in the present invention, the packet reception period for estimating a transmission waiting communication apparatus is a period from a transmission time point to a predetermined time before.

  (13) Further, the present invention is characterized in that packets are output almost periodically.

  According to the present invention, since the packet transmission probability is determined with equal probability based on the prediction of the collision, the dead time in terms of both the transmission waiting time and the collision probability can be set to a short time based on the predicted time. Since the transmission probability is also corrected for the prediction error, it is possible to reduce the dead time during which no communication device transmits even though there is a transmission waiting packet, and the throughput is improved.

  (1) According to the invention described in claim 1, since the packet transmission probability is determined with equal probability based on the prediction of collision, the dead time in terms of both transmission waiting time and collision probability is reduced to a short time based on the predicted time. can do. Also, for the collision prediction error, since the transmission waiting period and the transmission probability, or the transmission probability are determined again, the transmission probability is corrected, and there is a waiting time during which no communication device transmits even though there is a transmission waiting packet. And the throughput is improved.

  (2) According to the invention of claim 2, in addition to the effect of claim 1, it is possible to avoid a dead time in which no communication device transmits while there is a packet waiting for transmission due to a collision prediction error.

  (3) According to the invention described in claim 3, the effect described in claim 1 can be obtained. The transmission probability is changed by not transmitting any communication device due to the collision error. In this case, since the communication device has estimated the collision error to be small, it can be estimated that no communication device has transmitted, so the transmission probability In the modification, the transmission probability is corrected so that the communication device increases the transmission probability, that is, the transmission probability is increased, and the dead time during which no communication device transmits even though there is a transmission packet can be suppressed.

(4) According to the invention described in claim 4, the effect described in claim 1 can be obtained. Clarified changes to the transmission waiting period and transmission probability.
(5) According to the invention described in claim 5, the effect described in claim 1 can be obtained.

  (6) According to the present invention, the throughput can be improved. Clarified changes to the transmission waiting period and transmission probability. Although the communication device predicted the number of terminals waiting for transmission correctly compared to the previous collision prediction, several other communication devices waiting for transmission predicted a large number of communication devices waiting for transmission. Since the transmission probability has been reduced and no communication has been performed from any of the communication devices, if the transmission waiting period and the transmission probability are changed all at once as in claim 4, a terminal having the number of transmission waiting If the number of communication devices is large, the collision probability is high in the entire system, and the effect of improving the throughput is reduced. This is avoided by not using the communication device.

(7) According to the present invention, throughput can be improved.
(8) According to the present invention, throughput can be improved.
(9) According to the present invention, the throughput can be improved.

(10) According to the present invention, the throughput can be improved.
(11) According to the present invention, throughput can be improved.
(12) According to the present invention, throughput can be improved.

  (13) According to the present invention, the throughput can be improved. In a system in which packets are issued almost periodically, the fluctuation in the number of communication devices waiting for transmission does not become large, so collision prediction (estimation of the number of communication devices waiting for transmission) can be performed more accurately, and the effect of improving throughput is increased. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a flowchart showing an example of the operation of the present invention. First, the communication device receives a packet (S1). If the packet is received, it is checked whether there is a transmission packet to be transmitted next (S2). If there is no transmission packet, the packet reception in step S1 is continued. If there is a transmission packet, it is checked whether the packet reception has been performed for a period sufficient to estimate the number of communication apparatuses waiting for transmission (S3).

  If not, the packet is received until a time sufficient to estimate the number of communication devices waiting for transmission (S4). If the packet is received for a sufficient time in step S3, the number n of communication devices that are waiting to be transmitted when they transmit themselves is estimated (S5), and the dead time in terms of both transmission waiting time and collision probability is estimated from the estimated number n. The number s of transmission timing candidates and the transmission probability p are determined by a procedure determined in advance by the system (S6). Next, the parameter k is initialized to 1 (S7).

  Next, using the transmission probability p determined in step S6, the transmission timing candidate No. The transmission permission / inhibition is determined at k (S8). Next, it is checked whether or not transmission is possible (S9). If transmission is possible, the transmission timing candidate No. Wait for the timing of k (S10). If the timing is k, the packet is transmitted (S11). If transmission is impossible in step S9, the transmission timing candidate No. Wait for the timing of k (S12). If it is the timing k, it is checked whether there is any packet transmission from another communication device (S13).

  If a packet from another is received, the process ends. If no packet is received from another, k = k + 1 is calculated (S14), and it is checked whether k> s (S15). Here, s is the number of transmission timing candidates within the transmission standby period. That is, it is determined whether or not the transmission timing candidate k has reached the number s determined in step S6. If the contention window number k has not reached s, the process returns to step S8, determines whether transmission is possible with the next transmission timing candidate, with probability p, and repeats step S9 and subsequent steps.

  If the number of transmission timing candidates k has reached s in step S15, the estimated value of the communication apparatus waiting for transmission is corrected (S16), and the process returns to step S6 to return the number of transmission timing candidates s within the transmission waiting possible period, The transmission probability p is obtained again, and step S6 and subsequent steps are repeated.

According to this embodiment, the throughput can be improved.
FIG. 2 is a diagram showing the operation of the communication apparatus of the present invention. The horizontal axis is time. When there is a transmission waiting packet, the communication device performs carrier sense (checks whether there is a carrier wave) and waits for the end of transmission from another communication device. The number k of transmission timing candidates and the transmission probability p are determined from the estimation of the number of communication apparatuses waiting for transmission, and if transmission end is detected, whether transmission is possible is determined with the probability p.

  If transmission is not possible and no packet is received from another communication device, whether transmission is possible is determined with probability p up to CW2,... CWk. When one communication apparatus has not performed communication until CWk, a new CW number j−k from CWk + 1 and a transmission probability p ′ are determined, and whether transmission is possible is determined from CWk + 1 with a probability p ′. When one communication device has not performed communication until CWj, the number of CWs and the transmission probability from CWj + 1 are determined, and whether transmission is possible or not is determined from CWj + 1 with probability p ″. Throughput can be improved.

  FIG. 3 is an explanatory diagram of an example of a method for estimating the number of communication devices. In the figure, 1 is a normal reception packet and 2 is a collision packet. The communication device always receives packets transmitted by other communication devices, and it can be estimated that the number of normally received packets and the number of collision packets (reception power is detected with a sufficient value and packets are transmitted from other communication devices. When the data cannot be correctly decoded (when a CRC error added to the packet is detected, etc.).

  When a transmission packet is generated, the total number of normal reception packet number nr and collision packet number nc during the packet reception period tr (a period sufficient for estimation of a transmission waiting communication apparatus) is calculated. If all the packet lengths issued by the communication devices in the system are constant packet length tp (or the average packet length of the packets), a maximum of tr / tp packets can be transmitted during the packet reception period. The estimated number of communication devices is obtained from the number of normal received packets nr, the number of collision packets nc, and the maximum number of packets tr / tp during the packet reception period.

  For example, if nr = tr / tp, the communication device in which the transmission packet has occurred can always transmit the packet without collision, and any one of the communication devices transmits the packet during the entire period. = 1. If nr + nc = tr / tp, a plurality of communication devices perform transmission nr times. For example, if two communication devices simply perform simultaneous communication with large error, n = ( 2 * nr + nc) / (tr / tp). Here, a method for estimating the number of communication devices that is simple and has a considerably large error has been shown, but an embodiment with higher accuracy is also conceivable. According to this embodiment, the throughput can be improved.

  FIG. 4 is a diagram for explaining the operation of the embodiment of the present invention. In this method, the maximum number of transmission timing candidates is obtained, and transmission is performed with probability 1 when the maximum value is reached. That is, when carrier sensing is performed and the end of packet transmission from another communication apparatus is detected, CW1 to CWk are transmitted with probability p, CWk + 1 to CWj are transmitted with probability p ', and CWj + 1 is transmitted with probability p ". When CWmax is reached, transmission is performed with probability 1.

  According to the present invention, it is possible to increase the transmission probability every time the estimated error is corrected as p <p ′ <p ”in Fig. 2. In this way, the packet is increased by increasing the transmission probability every time the estimated error is corrected. Effective use of communication can be achieved.

  Further, according to the present invention, when the determination in step S15 is yes in FIG. 1, the estimated number of communication devices waiting for transmission in step S16 is always corrected, the transmission waiting period, the number of transmission timing candidates, and the transmission probability. (Or only the transmission probability) can be changed. According to this embodiment, the throughput can be improved.

  FIG. 5 is a flowchart showing an example of another operation of the present invention. The same reference numerals as those shown in FIG. 1 denote the same reference numerals. Compared with the flowchart shown in FIG. 1, the part of step S16 is changed to step S17 and step S18. If the number of contention windows determined in step S6 has been reached in step S15, it is next determined whether or not to change the transmission waiting communication apparatus estimated value with the probability pcn.

  If it is to be changed, the process returns from step S18 to step S6 as in the case of FIG. 1, and a new transmission standby period and the number of transmission timing candidates are determined. If not changed, the process returns to step S7, and the previous value is used without changing the transmission standby period, the number of transmission timing candidates, and the transmission probability. According to this embodiment, the throughput can be improved.

  FIG. 6 is a flowchart showing an example of another operation of the present invention. The same reference numerals as those shown in FIG. 1 denote the same reference numerals. Compared with the flowchart shown in FIG. 1, procedure steps S19 and S20 for dispersing the change timing are added between step S15 and step S16, step S7 is changed, and step S24 is added. If the number of transmission timing candidates determined in step S15 has been reached, a transmission probability change timing is set in step S20.

  In step S23, it is checked whether the change timing has come. If it is not time to change, the process returns to step S8 to determine whether transmission is possible with the previous transmission probability. When the change timing is reached, after resetting the value of x (S24), the process proceeds to step S16, and thereafter the same operation as in FIG. 1 is performed. This is because Steps S7 and S24 do not give the influence of delaying the change timing in order to distribute the change timing when changing the estimated number of communication apparatuses waiting to be transmitted next. According to this embodiment, the throughput can be improved.

  FIG. 7 is a diagram for explaining the first operation of the present invention. The communication devices 2 and 3 are communication devices in which a transmission packet is generated during data transmission of the communication device 1. After the data transmission of the communication device 1 is completed, the communication devices 1 and 3 each output an estimated value of the communication device waiting for transmission, 3) and its transmission probability (p in this example) are determined (circle 1). Since the packet is not transmitted from any communication device after three timings, the transmission probability is changed from p to p '(circle 2).

  After the change, a packet is transmitted from the communication device 3, the communication device 2 can recognize that the packet has been transmitted from the communication device 3, and waits for the transmission of the communication device 3 to end. According to this embodiment, the throughput can be improved.

  Further, according to the present invention, at the time of round 4 (the part where the transmission of the communication device 3 is completed and the communication device 2 determines the transmission standby period, the number of transmission timing candidates, and the transmission probability (or only the transmission probability)). Then, the transmission standby period, the number of transmission timing candidates, and the transmission probability are performed using the values of circle 2. According to this embodiment, the throughput can be improved.

  FIG. 8 is a diagram illustrating a second operation of the present invention. The difference from the case of FIG. 7 is that the transmission waiting period, the number of transmission timing candidates, and the transmission probability are performed using the value of circle 1 at the time of circle 4. According to this embodiment, the throughput can be improved.

  FIG. 9 is a diagram for explaining a third operation of the present invention. 7 and FIG. 8 are different from FIG. 7 in that the transmission waiting period, the number of transmission timing candidates, and the transmission probability at the time of circle 4 are the same as the previous transmission waiting period, the number of transmission timing candidates, and the transition of the transmission probability. This is a new decision based on the transition of the part 5). According to this embodiment, the throughput can be improved.

  FIG. 10 is a diagram for explaining a fourth operation of the present invention. As shown in the figure, the packet reception period for estimating the communication apparatus waiting for transmission is the time from when the previous packet is transmitted until the next packet occurs. According to this embodiment, the throughput can be improved.

  FIG. 11 is a diagram for explaining the fifth operation of the present invention. As shown in the figure, the packet reception period for estimating the transmission waiting communication apparatus is a time determined in advance by the system specifications or the like. According to this embodiment, the throughput can be improved.

  FIG. 12 is an operation sequence diagram of the present invention. As shown in the figure, packets are transmitted almost periodically for each communication device. In addition, although it is almost periodic as shown in the figure when a short section is viewed, there is a configuration in which the period slowly changes when viewed in a long period. According to this embodiment, the throughput can be improved.

(Appendix 1)
In a communication apparatus that performs packet transmission, determine the probability of transmission with a transmission waiting time period and a transmission timing candidate within each transmission waiting time period,
Decide whether to transmit based on the transmission probability for each transmission timing candidate,
Even if the predetermined transmission waiting period elapses, if transmission from itself or other transmission is not detected, determine the transmission waiting period and the transmission probability, or the transmission probability again,
A communication method in packet communication, wherein transmission possibility is determined based on a transmission probability at each transmission timing candidate.

(Appendix 2)
2. A communication method in packet communication according to appendix 1, wherein a maximum transmission waiting period or the maximum number of transmission timing candidates is determined, and transmission is performed with a probability of 1 when it becomes the last transmission timing candidate.

(Appendix 3)
The communication method in the packet communication according to appendix 1 or 2, wherein the transmission probability is corrected so as to increase the transmission probability.

(Appendix 4)
4. The communication method in packet communication according to any one of appendices 1 to 3, wherein when a predetermined transmission standby period is reached, the transmission standby period and the transmission probability, or only the transmission probability is corrected. .

(Appendix 5)
In a communication apparatus that performs packet transmission, probability determination means for determining a probability of transmission at a transmission waiting time period and a transmission timing candidate within each transmission waiting time period; and
Transmission availability determination means for determining transmission availability based on the transmission probability for each transmission timing candidate;
When a predetermined number of transmission standby periods have elapsed, if the transmission is performed by itself or transmission from another is not detected, the transmission waiting period and the transmission probability, or the determination means for determining the transmission probability again When,
Comprising
The communication apparatus in packet communication, wherein the transmission permission / inhibition determining means determines transmission permission / inhibition based on a transmission probability at each transmission timing candidate.

(Appendix 6)
The supplementary transmission waiting period and the transmission probability, or only the transmission probability is corrected at a predetermined probability when a predetermined transmission standby possible period is reached. Communication method in packet communication.

(Appendix 7)
The communication in the packet communication according to any one of appendices 1 to 3, wherein when a predetermined transmission waiting period is reached, the transmission waiting period and the transmission probability, or the correction timing of only the transmission probability is distributed. Method.

(Appendix 8)
When another communication apparatus performs transmission and transmission is not possible, the next transmission standby period and the transmission probability, or only the transmission probability uses the value when the other communication apparatus transmits. 8. A communication method in packet communication according to any one of appendices 1 to 4 or appendix 6 or 7.

(Appendix 9)
When other communication devices transmit and cannot transmit, the next transmission waiting period and transmission probability, or only the transmission probability uses the transmission waiting period and transmission probability based on the previous first predicted value. 8. A communication method in packet communication according to any one of appendices 1 to 4 or appendix 6 or 7,

(Appendix 10)
When other communication devices transmit and transmission is not possible, the next transmission standby period and transmission probability, or only the transmission probability uses the transmission standby period and transmission probability reflecting the previous transition. The communication method in the packet communication according to any one of Supplementary Notes 1 to 4 or Supplementary Notes 6 or 7.

(Appendix 11)
The packet reception period for estimating the communication apparatus waiting for transmission is a period between transmission of the previous packet and transmission of the next packet. A communication method in the packet communication described.

(Appendix 12)
The packet reception period for estimating the communication apparatus waiting for transmission is a period from a transmission time point to a predetermined time before the packet, according to any one of the supplementary notes 1 to 4 and the supplementary notes 6 to 10 Communication method in communication.

  (Supplementary note 13) The communication method in packet communication according to any one of Supplementary notes 1 to 4 or Supplementary notes 6 to 12, characterized in that, in the present invention, packets are output almost periodically.

  As described above in detail, according to the present invention, since the packet transmission probability is determined with equal probability based on the prediction of collision, the dead time in terms of both transmission waiting time and collision probability is short based on the predicted time. The transmission probability is also corrected for collision prediction errors, so it is possible to reduce the dead time during which no communication device transmits even though there are packets waiting to be transmitted, improving throughput. To do.

It is a flowchart which shows an example of operation | movement of this invention. It is a figure which shows operation | movement of the communication apparatus of this invention. It is explanatory drawing of an example of the estimation method of the number of communication apparatuses. It is operation | movement explanatory drawing of embodiment of this invention. It is a flowchart which shows an example of the other operation | movement of this invention. It is a flowchart which shows an example of the other operation | movement of this invention. It is a 1st operation explanatory view of the present invention. It is a 2nd operation explanatory view of the present invention. It is a 3rd operation explanatory view of the present invention. It is the 4th operation explanatory view of the present invention. It is a 5th operation explanatory view of the present invention. It is a figure which shows the operation | movement sequence of this invention.

Claims (5)

In a communication apparatus that performs packet transmission, determine the probability of transmission with a transmission waiting time period and a transmission timing candidate within each transmission waiting time period,
Decide whether to transmit based on the transmission probability for each transmission timing candidate,
Even if the predetermined transmission waiting period elapses, if transmission from itself or other transmission is not detected, determine the transmission waiting period and the transmission probability, or the transmission probability again,
A communication method in packet communication, wherein transmission possibility is determined based on a transmission probability at each transmission timing candidate.   2. The communication method in packet communication according to claim 1, wherein a maximum transmission waiting period or the maximum number of transmission timing candidates is determined, and transmission is performed with a probability of 1 when it becomes the last transmission timing candidate.   3. The communication method in packet communication according to claim 1, wherein the transmission probability is corrected so as to increase the transmission probability.   The communication in packet communication according to any one of claims 1 to 3, wherein, when a predetermined transmission waiting period is reached, the transmission waiting period and the transmission probability, or only the transmission probability is corrected. Method. In a communication apparatus that performs packet transmission, probability determination means for determining a probability of transmission at a transmission waiting time period and a transmission timing candidate within each transmission waiting time period; and
Transmission availability determination means for determining transmission availability based on the transmission probability for each transmission timing candidate;
When a predetermined number of transmission standby periods have elapsed, if the transmission is performed by itself or transmission from another is not detected, the transmission waiting period and the transmission probability, or the determination means for determining the transmission probability again When,
Comprising
The communication apparatus in packet communication, wherein the transmission permission / inhibition determining means determines transmission permission / inhibition based on a transmission probability at each transmission timing candidate.

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