JP3935463B2 - Wireless communication system and program for causing computer to execute transmission / reception of data in the wireless communication system - Google Patents

Description

  The present invention relates to a wireless communication system with less data loss and less waiting time in wireless communication, and a program for causing a computer to perform data transmission / reception in the wireless communication system.

  IEEE 802.11 ad-hoc mode communication, which is one of the standards for wireless communication, does not require a base station and can communicate anytime, anywhere. Recently, it has been expected to realize a new service that could not be realized in a wired network by using the IEEE 802.11.

  In applications where small control packets are exchanged in real time using wireless packet communication, latency is a serious problem. Therefore, in applications that require real-time performance, UDP (User Datagram Protocol) communication is often used because the control overhead is less than TCP (Transmission Control Protocol) communication. Also, broadcast communication that transmits the same data to a plurality of terminals is often used.

  As described above, in applications that require real-time performance, data is often transmitted using UDP in broadcast communication.

On the other hand, as a method of transmitting data collectively, a method of extracting data transmitted in the past, creating transmission data together with newly transmitted data (Patent Document 1), and a communication environment of an IP protocol A method of collecting a plurality of IP packets to be used, storing them in one data link frame and transmitting them (Patent Document 2) is known.
JP 2001-313637 A JP 2003-78565 A

  However, in broadcast communication, the waiting time can be reduced, but since data is not retransmitted, there is a problem that packet loss occurs due to collision even when there are very few nodes within the same radio wave range.

  In unicast communication, data retransmission is performed, so that packet loss due to collision can be reduced. However, since one-to-one communication is performed between the transmission side and the reception side, there is a problem that waiting time increases. is there.

  Furthermore, Patent Document 1 is for reducing communication traffic associated with data retransmission, and Patent Document 2 is for improving throughput in a wireless packet communication system. In the system, there is a problem that it is difficult to suppress data loss and to shorten the waiting time for wireless communication.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide a wireless communication system capable of suppressing the loss of data and reducing the waiting time of wireless communication. .

  Another object of the present invention is to provide a program for causing a computer to execute data transmission / reception in a wireless communication system capable of suppressing data loss and shortening the waiting time of wireless communication.

According to the present invention, the wireless communication system includes a transmitter and a receiver. Each transmitter transmits k data (k is a natural number satisfying 1 ≦ k ≦ R, R is a natural number equal to or greater than 2) once every arbitrary time, thereby transmitting each of k data. Is transmitted k times or more. The receiver receives k pieces of data in the wireless communication space and reproduces new data among the k pieces of data. Then, the transmitter transmits k data once every predetermined time or every time data is generated within a predetermined time in any one of the first and second modes. Are transmitted R times or more. In the first mode, when new data is generated within a predetermined time, the new data is added to the already transmitted data so as to be generated in order of generation. The second mode is a mode for transmitting data held in the transmitter when a predetermined time has elapsed when new data is not generated within the predetermined time .

Preferably, in the first mode, when new data is generated within a predetermined time, the oldest data among the R data is deleted, and the new data has already been transmitted so as to be generated. A mode in which R data added to one data is transmitted, and when new data is generated within a predetermined time, the data added to the data that has already been transmitted so that the new data is generated is transmitted. Mode .

Preferably, the transmitter generates new data within a predetermined time by a data generation unit that generates data, a buffer capable of storing R data, a transmission unit that transmits data, and the data generation unit. Create k data by adding new data to the data stored in the buffer so as to be generated and output it to the transmission unit. When the data generation unit does not generate new data within a predetermined time, store it in the buffer. A data control unit that reads out the read data and outputs the read data to the transmission unit .

Preferably, the data controller determines whether or not the number of data stored in the buffer is R when new data is generated within a predetermined time, and determines the number of data stored in the buffer. When R is R, the oldest data among the R data is deleted, and new data is added to R-1 data so as to be generated and output to the transmission unit .

Preferably, the data controller determines whether or not the number of data stored in the buffer is R when new data is generated within a predetermined time, and determines the number of data stored in the buffer. When R is less than R, new data is added to the data stored in the buffer so as to be generated and output to the transmission unit until the number of data stored in the buffer reaches R, in order of generation .

Preferably, the buffer stores new data sequentially generated in association with sequentially increasing sequence numbers. When new data is generated by the data generation unit, the data control unit gives the new data a sequence number consecutive to the maximum sequence number used in the buffer, and when the buffer is full, the smallest sequence number And the new data is added to the R-1 data so as to be in the order of the sequence numbers and is output to the transmitting unit. When the buffer is not full, the new data is assigned in the order of the sequence numbers. Add and output to the transmitter .

Preferably, when the number of times that new data is not generated within a predetermined time reaches a predetermined number , the data control unit stops the output of the data stored in the buffer to the transmission unit and waits .

Preferably, in the first mode, when new data is generated within a predetermined time, the oldest data of k data is deleted, and new data has already been transmitted so as to be transmitted R times. In this mode, k data added to k-1 data are transmitted .

Preferably, the transmitter repeatedly transmits each of the k data R times by transmitting the k data once every predetermined time or every time data is generated within the predetermined time. A transmitter generates a data, a buffer capable of storing R data, a transmitter that transmits data, and a new data generated by the data generator within a predetermined time. The oldest data among the stored data is deleted, k data with new data added so as to be transmitted R times are generated and output to the transmission unit, and the new data is generated within a predetermined time by the data generation unit. And a data control unit that reads data stored in the buffer and outputs the data to the transmission unit when it is not generated .

Preferably, when the buffer becomes empty , the data control unit further stops transmission of k data and waits .

Preferably, the buffer has R addresses capable of storing R data, and stores k data to which sequentially increasing sequence numbers are assigned in the order of generation. When new data is generated by the data generation unit, the data control unit assigns a sequence number continuous to the maximum sequence number used in the buffer to the new data, and the data stored in the first address of the buffer Is deleted, the remaining data is shifted to an address with a smaller address number, and new data is added to the Rth address of the buffer and output to the transmitter .

Preferably, the data control unit further deletes the data stored in the first address of the buffer and shifts the remaining data to an address having a smaller address number when new data is not generated within a predetermined time. Then, the data stored in the buffer is read and output to the transmission unit .

Further, according to the present invention, a program for causing a computer to execute is a program for causing a computer to execute data transmission / reception in a wireless communication system including a transmitter and a receiver arranged in a wireless communication space. , K (k is a natural number satisfying 1 ≦ k ≦ R, R is a natural number of 2 or more) data is transmitted once every arbitrary time, so that each of the k data is k times. The computer executes the first step transmitted by the transmitter and the second step in which the receiver receives k data in the wireless communication space and reproduces new data out of the k data. In one step, the transmitter sends each of k data R times or more by transmitting k data once every predetermined time or every time data is generated within a predetermined time. The first step includes a first sub-step for generating new data within a predetermined time, and a buffer for the transmitter so that the new data is generated in the order of generation when the new data is generated within the predetermined time. A second sub-step for transmitting in addition to the data stored in the memory, and a third sub-step for reading and transmitting the data stored in the buffer when new data is not generated within a predetermined time .

Preferably, the second sub-step is stored in the buffer with step A for determining whether the number of data stored in the buffer is R when new data is generated within a predetermined time. When the number of data is R, Step B for deleting the oldest data out of the R data, and adding new data to the R-1 data so as to be in the order of generation, R data Including step C.

Preferably, in the second sub-step, when the number of data stored in the buffer is less than R, new data is added to the data stored in the buffer so as to be generated in order of generation and transmitted. Further included .

Preferably, step D is repeatedly executed until the number of data stored in the buffer reaches R.

Preferably, the third sub-step includes a step of determining whether or not the number of times that new data is not generated within a predetermined time is less than the predetermined number of times, and the number of times that new data is not generated within a predetermined time is a predetermined number of times. When the number of times that the number of times new data has not been generated within a predetermined time has reached a predetermined number of times, the transmission of the data stored in the buffer is stopped. Waiting .

Preferably, the second sub-step deletes the oldest data stored in the buffer when new data is generated within a predetermined time and deletes the new data so that the new data is sent R times The third sub-step deletes the oldest data stored in the buffer when no new data is generated within a given time, Send the remaining data other than the oldest deleted data .

Preferably, the first step further includes a fourth sub-step of stopping and waiting for transmission of data stored in the buffer when the transmitter buffer becomes empty .

  In the wireless communication system according to the present invention, when one data is generated every arbitrary time, the transmitter deletes the oldest data, adds the newly generated data, and transmits the newly generated data to the receiver. Therefore, the transmitter transmits each piece of data R times or more while increasing the number of transmissions of the same data every arbitrary time. Then, the receiver reproduces newly received data among the data received from the transmitter. As a result, when the same data is retransmitted, loss of data in the wireless communication space is suppressed, and accordingly, the waiting time for wireless communication is reduced.

  Therefore, according to the present invention, data loss can be suppressed and waiting time can be shortened.

  Embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic block diagram of a radio communication system according to an embodiment of the present invention. The wireless communication system 100 includes terminal devices 11 to 1N (N is a natural number of 2 or more). The terminal devices 11 to 1N are arranged in the wireless communication space 30. And the terminal devices 11-1N are each provided with the antennas 21-2N, and mutually transmit / receive data in the wireless communication space 30 using the ad hoc mode communication of IEEE802.11. More specifically, each of the terminal devices 11 to 1N transmits a packet composed of k pieces of data (k is a natural number satisfying 1 ≦ k ≦ R, R is a natural number of 2 or more) at predetermined time intervals by broadcast communication or Each time the data is generated within a predetermined time, the data is transmitted and received once, so that each of the k data is transmitted and received R times or more.

  Since the terminal devices 11 to 1N transmit and receive packets by broadcast communication, in the following description, one terminal device 11 among the terminal devices 11 to 1N is set as the transmitter TX, and N-1 terminals. The devices 12 to 1N will be described as a receiver RX.

  FIG. 2 is a functional block diagram of the terminal device 11 shown in FIG. 3 and 4 are packet configuration diagrams. The terminal device 11 includes a transmission / reception unit 110, a buffer 120, a data control unit 130, a data generation unit 140, a data reproduction unit 150, and a counter 160.

  The transmission / reception unit 110 includes the antenna 21 shown in FIG. Then, the transmission / reception unit 110 transmits the packet received from the data control unit 130 to the other terminal devices 12 to 1N in the wireless communication space 30 by broadcast communication, and transmits the packet from the other terminal devices 12 to 1N in the wireless communication space 30. Receive and output to the data control unit 130.

  The buffer 120 can store R data D (1), D (2), D (3),..., D (R). And R pieces of data D (1), D (2), D (3),..., D (R) are p-R + 1, p-R + 2, p-R + 3,. Sequence number is assigned. Therefore, the buffer 120 corresponds to the R data D (1), D (2),..., D (R) to the sequence numbers p-R + 1, p-R + 2, p-R + 3,. Add and remember.

  Data control unit 130 performs the following operation when data is transmitted. The data control unit 130 has a built-in timer, and when the data is output to the transmission / reception unit 110, the predetermined time T is measured by the timer. When the data control unit 130 receives new data D (NEW) from the data generation unit 140 within the predetermined time T, the data control unit 130 determines whether or not the data stored in the buffer 120 is full. When the data stored in the buffer 120 is full, the data control unit 130 deletes the data D (1) to which the minimum sequence number p-R + 1 is assigned, and is added to the data stored in the buffer 120. The sequence number p + 1 that is continuous to the maximum sequence number p is assigned to the new data D (NEW). Then, the data control unit 130 stores the data D (NEW) assigned the sequence number p + 1 in the buffer 120 following the data D (R) assigned the sequence number p.

  As described above, when the data stored in the buffer 120 is full, the data control unit 130 deletes the data with the smallest sequence number (the oldest data) and changes the data stored in the buffer 120 to the data stored in the buffer 120. A sequence number consecutive to the assigned sequence number is assigned to the newly generated data and stored in the buffer 120. Thereby, the buffer 120 stores R pieces of data.

  Further, the data control unit 130, when the data stored in the buffer 120 is not full, that is, m (m is a natural number satisfying m <R) pieces of data D (1), D (2), D (3 ),..., D (m) is stored in the buffer 120, the sequence number p-R + m + 1 that is consecutive to the maximum sequence number p-R + m assigned to the data stored in the buffer 120 is newly set. Assigned to data D (NEW). Then, the data control unit 130 stores the data D (NEW) assigned the sequence number p−R + m + 1 in the buffer 120 following the data D (m) assigned the sequence number p−R + m. In this case, the data control unit 130 stores the newly generated data in the buffer 120 until the data stored in the buffer 120 is full, that is, until R data is stored in the buffer 120. Append to data. When the number of data stored in the buffer 120 reaches R, the number of data stored in the buffer 120 is held at R by the method described above.

  The data control unit 130 assigns a sequence number to the newly generated data D (NEW) by the two methods described above, and stores the sequence number in the buffer 120. Then, the data control unit 130 adds data D (2), D (3),..., D (R), D (NEW) or D (1) to which newly generated data D (NEW) is added. , D (2), ..., D (m), D (NEW) are read from the buffer 120, and the read data D (2), D (3), ..., D (R), D ( NEW) or D (1), D (2),..., D (m), D (NEW) with a header added to create one packet.

  When creating one packet, the data control unit 130 outputs the created one packet to the transmission / reception unit 110, resets the built-in timer, and measures the predetermined time T.

  When the data control unit 130 does not receive new data D (NEW) from the data generation unit 140 within a predetermined time T, the data control unit 130 stores the data D (1), D (2),. ., D (j) (j is a natural number satisfying j ≦ R), and a header is added to the read data D (1), D (2),. Create a packet. Then, the data control unit 130 outputs the created one packet to the transmission / reception unit 110, generates a signal NGD indicating that no new data D (NEW) has been generated within a predetermined time T, and outputs the signal NGD to the counter 160. Output.

  The data control unit 130 stores the data D (1), D (2) stored in the buffer 120 when the predetermined time T has elapsed until the predetermined number of times that no new data D (NEW) is generated within the predetermined time T. ,..., D (j) to create one packet and output it to the transceiver 110.

  More specifically, the data control unit 130 receives the count value CNT from the counter 160, and when the received count value CNT is equal to or less than a predetermined number of times, the data D ( 1), D (2),..., D (j) are read from the buffer 120, and one packet is created from the read data D (1), D (2),. When the count value CNT reaches a predetermined number of times, transmission of data D (1), D (2),..., D (j) stored in the buffer 120 is stopped. And wait.

  The data control unit 130 continues the above-described operation until the end command FNH is received.

  The predetermined time T described above is T = D, where D is the maximum waiting time allowed by the application to be used, and n is the number of terminal devices used simultaneously (n is a natural number satisfying 1 ≦ n ≦ N). / (N × R). That is, the predetermined time T is set shorter as the number of destination terminal devices increases or as the number of data transmitted in one packet increases.

  Since the data control unit 130 creates one packet by the above-described method and outputs it to the transmission / reception unit 110 at every predetermined time T or every time data is generated within the predetermined time T, the terminal device 11 One packet is transmitted by broadcast communication every T or every time data is generated within a predetermined time T.

  Further, each of the data D (1), D (2),..., D (R) described above has a relatively small data size. For example, each of the data D (1), D (2),..., D (R) has a size smaller than the size into which the packet is divided. More preferably, the data size of each of the data D (1), D (2),..., D (R) is determined such that the product of the data size and R is smaller than 1500 bytes.

  Data control unit 130 performs the following operation when receiving data. When receiving one packet from the transmission / reception unit 110, the data control unit 130 stores k data included in the packet in the buffer 120. Then, the data control unit 130 determines whether or not the k data includes the same data as the already received data.

  When the same data is included, the data control unit 130 deletes duplicate data, reads only new data from the buffer 120, and outputs it to the data reproduction unit 150. In addition, when the k data does not include the same data as the already received k data, the data control unit 130 reads all the received k data from the buffer 120 and reads the data reproducing unit. To 150.

  As shown in FIG. 4, the transmission / reception unit 110 receives R data D (1), D (2),..., D (R); D (3), at timings t = T1, T2, and T3, respectively. D (4), ..., D (R + 1), D (R + 2); D (R + 3), D (R + 4), ..., D (2R + 2) are received. That is, the transmission / reception unit 110 receives R data every predetermined time T or every time data is generated within the predetermined time T.

  Then, after R data D (1), D (2),..., D (R) are received, R data D (3), D (4),. When R + 1) and D (R + 2) are received, the data control unit 130 is included in R data D (3), D (4),..., D (R + 1), D (R + 2). Of the data, the data D (3), D (4),..., D (D) that overlap the R data D (1), D (2),. R) is deleted, and data D (R + 1) and D (R + 2) are extracted.

  In addition, after R data D (3), D (4),..., D (R + 1), D (R + 2) are received, R data D (R + 3), D (R + 4),. .., When D (2R + 2) is received, the data control unit 130 determines that R data D (R + 3), D (R + 4),..., D (2R + 2) have already been received. When it is determined that the data D (3), D (4),..., D (R + 1), D (R + 2) is not included, R data D (R + 3), D (R + 4),. , D (2R + 2) are extracted.

  Thereby, even if a packet loss occurs, the data after the data in which the packet loss has occurred can be received and reproduced again.

  The data generation unit 140 generates new data D (NEW), and outputs the generated data D (NEW) to the data control unit 130. Data reproduction unit 150 reproduces data received from data control unit 130. Upon receiving the signal NGD from the data control unit 130, the counter 160 increments the count value CNT by 1, and outputs the incremented count value CNT to the data control unit 130.

  Each of the terminal devices 12 to 1N has the same configuration as the terminal device 11.

  FIG. 5 is a flowchart for explaining an operation in transmitter TX (terminal device 11) shown in FIG. When the operation in the transmitter TX is started, the data generation unit 140 generates new data D (NEW) and outputs the generated data D (NEW) to the data control unit 130. Then, the data control unit 130 determines whether or not the end command FNH is received (step S1), and when the end command FNH is received, the operation in the transmitter TX ends.

  On the other hand, when the end command FNH is not received, the data control unit 130 determines whether or not data is generated based on whether or not the data D (NEW) is received from the data generation unit 140 (step S2).

  When data is generated, the data control unit 130 initializes the counter 160 (step S3) and determines whether or not the buffer 120 is full (step S4). More specifically, the data control unit 130 determines whether or not the buffer 120 is full depending on whether or not the difference between the maximum value and the minimum value of the sequence numbers assigned to the data stored in the buffer 120 is R. Determine whether. In this case, the data control unit 130 determines that the buffer 120 is full when the difference between the maximum value and the minimum value is R, and the buffer 120 is full when the difference between the maximum value and the minimum value is not R. It is determined that it is not.

  When it is determined in step S4 that the buffer 120 is full, the data control unit 130 stores the data D (1), D (2), D (3),. R), the first data D (1) is deleted (step S5), and R−1 pieces of data D (2), D (3),. R) is shifted one by one (step S6). Then, the data control unit 130 assigns the sequence number p + 1 to the newly generated data D (NEW) (step S7), and sets the new data D (NEW) as the Rth data in the buffer 120 (step S8). ). That is, the data control unit 130 sets the data D (NEW) following the data D (R) assigned the sequence number p (see FIG. 3).

  Thereafter, the data control unit 130 reads R data D (2), D (3),..., D (R), D (NEW) from the buffer 120, and reads the R data D ( 2), D (3),..., D (R), D (NEW) are added to create a single packet. Then, the data control unit 130 outputs the created one packet to the transmission / reception unit 110, and the transmission / reception unit 110 transmits the one packet to the receiver RX in the wireless communication space 30 (step S9). Thereafter, the data control unit 130 sets a built-in timer and measures a predetermined time T (step S10). And a series of operation | movement transfers to step S1.

  On the other hand, when it is determined in step S4 that the buffer 120 is not full, the data control unit 130 assigns the sequence number p-R + m + 1 to the new data D (NEW) (step S11). In this case, the data control unit 130, when the data D (NEW) is generated, the data D (1), D (2), D (3),. m) Among the sequence numbers p-R + 1, p-R + 2, p-R + 3,..., p-R + m assigned to m), the sequence number p-R + m + 1 continuing to the maximum value p-R + m is used as the data D (NEW). (See FIG. 3).

  Then, the data control unit 130 converts the new data D (NEW) into the data D (1), D (2), D (3),. m) (step S12). That is, the data control unit 130 sets data D (NEW) following data D (m) (see FIG. 3).

  Thereafter, the data control unit 130 reads the data D (1), D (2), D (3),..., D (m), D (NEW) from the buffer 120, and the read data D (1 ), D (2), D (3),..., D (m), D (NEW), a header is added to create one packet. Then, the data control unit 130 outputs the created one packet to the transmission / reception unit 110. The transmission / reception unit 110 transmits one packet to the receiver RX in the wireless communication space 30 (step S9). Thereafter, step S10 is executed, and the series of operations proceeds to step S1.

  Further, when it is determined in step S2 that data has not been generated, the data control unit 130 determines whether or not a fixed time T has elapsed due to the time measured by the built-in timer (step S13). And when the fixed period T has not passed, a series of operation | movement transfers to step S1.

  On the other hand, when the predetermined time T has elapsed (step S13), the data control unit 130 generates the signal NGD and outputs it to the counter 160, and the counter 160 increments the count value CNT by 1 in accordance with the signal NGD (step S13). In step S14, the incremented count value CNT is output to the data control unit 130.

  Then, the data control unit 130 determines whether or not the count value CNT has reached a predetermined number (upper limit) (step S15). When the count value CNT has reached the predetermined number (upper limit), data transmission is performed. Cancel. Thereafter, the series of operations proceeds to step S1.

  On the other hand, when it is determined in step S15 that the count value CNT has not reached the predetermined number of times (upper limit), the data control unit 130 stores the data D ( 1), D (2), D (3),..., D (j), and the read data D (1), D (2), D (3),. ) To add a header to create one packet. Thereafter, the data control unit 130 outputs one packet to the transmission / reception unit 110, and the transmission / reception unit 110 transmits one packet to the receiver RX in the wireless communication space 30 (step S9). And step S10 mentioned above is performed and a series of operation | movement transfers to step S1.

  In the flowchart shown in FIG. 5, when the buffer 120 is full, when the new data D (NEW) is generated, the path of steps S5 to S9 is the data D (1) to which the minimum sequence number is assigned. Is deleted, and new data D (NEW) is added to transmit one packet of R data. That is, the route of steps S5 to S9 is the oldest data D (1) among the R data D (1), D (2), D (3),. Are deleted one by one each time new data D (NEW) is generated, and new data D (NEW) is shifted while shifting the remaining R-1 data one by one in the direction of increasing the number of transmissions. This is a route for additionally transmitting R data.

  Therefore, in the route of steps S5 to S9, each of R data D (1), D (2), D (3),..., D (R) is transmitted R times. That is, when the data generation rate is high, the transmitter TX transmits the same data R times.

  The paths in steps S11, S12, and S9 are paths for transmitting new data D (NEW) while adding to the data in the buffer 120 when the buffer 120 is free. In this case, since the oldest data D (1) stored in the buffer 120 is not deleted until the number of data in the buffer 120 reaches R, the data D (1), D (2), D Each of (3),..., D (m) is transmitted R times. That is, also in this case, the transmitter TX transmits the same data R times.

  Furthermore, the route of steps S13, S14, S15, and S9 is based on the data D (1), D stored in the buffer 120 at that time if new data D (NEW) is not generated within a certain period T. (2), D (3),..., D (j). Then, once data D (1), D (2), D (3),..., D (j) are transmitted, if it is determined in step S2 that data has been generated, steps S5 to S9 are performed. Or the data D (1), D (2), D (3),... Transmitted via the paths S13, S14, S15, S9. , D (j) are transmitted R times or more until the count value CNT reaches the upper limit. That is, when the data generation rate is low, the transmitter TX transmits the same data R times or more.

  Thus, in the present invention, the transmitter TX transmits the same data R times or more. As a result, when the same data is retransmitted, data loss in the wireless communication space 30 is suppressed with a short waiting time. Therefore, according to the present invention, data loss can be suppressed with a short waiting time.

  FIG. 6 is a flowchart for explaining the operation in receiver RX (terminal devices 12 to 1N) shown in FIG. When the operation of the receiver RX is started, the data control unit 130 of the receiver RX determines whether or not the end command FNH is received (step S21). When the end command FNH is received, a series of operations are performed. finish.

  On the other hand, when the data control unit 130 does not receive the end command FNH, the transmission / reception unit 110 receives a packet transmitted from the transmitter TX in the wireless communication space 30 (step S22), and receives the received packet as the data control unit 130. Output to.

  The data control unit 130 stores the packet from the transmission / reception unit 110 in the buffer 120 (step S23). Then, the data control unit 130 receives the same data as the already received data D (1), D (2),..., D (k), and newly received data D (2), D (3), ..., it is determined whether it is included in D (k + 1). In other words, the data control unit 130 has newly received data having the same sequence number as the sequence number assigned to the already received data D (1), D (2), ..., D (k). It is determined whether data D (2), D (3),..., D (k + 1) exists (step S24).

  When data with the same sequence number is present, the data control unit 130 deletes duplicate data and extracts only new data D (k + 1). Data control unit 130 reads the extracted data D (k + 1) from buffer 120 and outputs the data to data reproduction unit 150. The data reproducing unit 150 reproduces the data D (k + 1) from the data control unit 130 (step S25).

  On the other hand, when it is determined in step S24 that there is no data to which the same sequence number is assigned, the data control unit 130 receives the newly received data D (k + 2), D (k + 3),. k + R + 1) is read from the buffer 120 and output to the data reproducing unit 150. Then, the data reproducing unit 150 reproduces D (k + 2), D (k + 3),..., D (k + R + 1) (step S26). Thereafter, the process proceeds to step S1, and when the end command FNH is received, the operation in the receiver RX ends.

  FIG. 7 is a diagram showing a change in the packet error rate with respect to the number of terminal apparatuses when broadcast is used assuming an ensemble by MIDI (Musical Instruments Digital Interface) as an example. Here, the MIDI data is 3 bytes. In FIG. 7, the horizontal axis represents the number of terminal devices, and the vertical axis represents the packet error rate. Curves k1, k2, k3, and k4 indicate changes in the packet error rate with respect to the number of terminal apparatuses when the number of transmissions is 1, 2, 4, and 5, respectively. Furthermore, the maximum number of terminal devices is nine. These nine are the number of terminal devices that cause a packet error rate of about 0.3 due to collision when the packet is not retransmitted.

The packet error rate increases as the number of terminal devices increases at each transmission count. In each terminal device, the packet error rate decreases as the number of transmissions increases. If the packet is retransmitted five times, the packet error rate due to collision decreases to 10 ⁻⁴ even when the number of terminal devices is nine. Therefore, by transmitting the same packet five times, the packet error rate is greatly reduced from 0.3 to 10 ⁻⁴ .

  This means that in broadcast communication, retransmitting the same data is effective in reducing the packet error rate. As another method of reducing the packet error rate, a method of individually transmitting to terminals other than itself using unicast communication is conceivable. In applications that require real-time performance, latency is a problem, so the latency of these two methods is compared. Again, assuming a ensemble using MIDI in a wireless environment, the data size is 3 bytes.

  FIG. 8 is a diagram illustrating a change in waiting time with respect to the number of terminal devices. In FIG. 8, the horizontal axis represents the number of terminal devices, and the vertical axis represents the waiting time. Symbol U represents a case where unicast communication is used to individually transmit to a terminal other than itself, and symbol B represents a case where the same packet is individually transmitted five times by broadcast communication.

  In both unicast communication U and broadcast communication B, the waiting time increases as the number of terminal devices increases. In addition, the broadcast communication B has a lower waiting time than the unicast communication U in each terminal device number. The waiting time is less than 20 msec for broadcast communication, and less than 50 msec for unicast communication. Therefore, when the number of terminal devices is the same, it is possible to reduce the waiting time by using the broadcast communication and individually transmitting the same packet a plurality of times than using the unicast communication.

  From the results described with reference to FIGS. 7 and 8, it is effective to retransmit the same packet multiple times in broadcast communication in order to reduce the packet error rate and reduce the waiting time. Here, this method is called a multiple broadcast communication method.

  The waiting times in the unicast communication system and the multiple broadcast communication system are determined by the following equations (1) and (2), respectively.

T _U = (N-1) {(N + Q (N, C _W )) [(L _D + L _H ) 8 / Trans + H _U ] + ST _U } (1)
However, T _U : Waiting time, N: Number of terminal devices, Q (N, C _W ): Expected number of transmissions, C _W : Minimum backoff, L _D : Data size, L _H : Header size, Trans: Transfer Rate, H _U : Overhead in unicast communication, ST _U : Average slot time in unicast communication
T _MB-R = R {N [(L _D + L _H ) 8 / Trans + H _B ] + ST _B } (2)
However, T _MB-R : Waiting time, R: Number of data included in one packet, H _B : Overhead in broadcast communication, ST _B : Average slot time in broadcast communication Further, the waiting time of the communication method according to the present invention is Determined by equation (3).

T _CB-M = M <N {[R (L _S + L _D ) + L _H ] 8 / Trans + H _B } + ST _B > (3)
However, T _CB-M : Waiting time, L _S : Number of bytes of sequence number, M: Number of transmissions when packet transmission succeeds for the first time FIG. 9 is expressed by equations (1), (2) and (3) It is a figure which shows the relationship between the waiting time represented and the number of terminal devices. In FIG. 9, the horizontal axis represents the number of terminal devices, and the vertical axis represents the waiting time. Curves k5 and k6 show the relationship between the waiting time and the number of terminal devices in the case of the unicast communication method, and the straight lines k7, k9 and k10 show the waiting time and the number of terminal devices in the case of the communication method according to the present invention. The straight line k8 indicates the relationship between the waiting time and the number of terminal devices in the case of the multiple broadcast communication method.

  In the curves k5 and k6, the transfer rates Trans are 2 [Mbps] and 11 [Mbps], respectively. On the straight lines k7 to k10, the transfer rate Trans is 2 [Mbps].

In unicast communication system, the waiting time T _U sharply increases with an increase in the number of terminal devices. The waiting time T _U is the number of terminal devices is up to five holds 40 [msec] or less (see curve k5, k6).

In the multiple broadcast communication system and the communication system according to the present invention, the waiting times T _MB-R and T _CB-M increase almost linearly, and even when the number of terminal devices is nine, it is maintained at 25 [msec] or less. . In the communication system according to the present invention, since the number of transmissions when receiving a packet for the first time with a very high probability is less than 5, the waiting time T _CB-M is set to the waiting time T _CB-M in the multiple broadcast communication system. Less than _MB-R .

  In this way, by transmitting and receiving the same data R times or more according to the flowcharts shown in FIGS. 5 and 6 described above, the receiver RX can reduce the packet loss due to collision and reduce the waiting time, thereby reducing the transmitter TX. Can receive data from.

  In the present invention, the terminal devices 11 to 1N illustrated in FIG. 1 may include the terminal device 11A illustrated in FIG. FIG. 10 is another functional block diagram of terminal apparatuses 11 to 1N shown in FIG. FIG. 11 is a packet configuration diagram. The terminal device 11A is the same as the terminal device 11 except that the counter 160 of the terminal device 11 is deleted and the data control unit 130 is replaced with the data control unit 130A.

  The buffer 120 stores R data D (1) to D (R) at R addresses B (1) to B (R). When new data D (NEW) is generated within a predetermined time T, the data control unit 130A has the highest sequence number among the R data D (1) to D (R) stored in the buffer 120. The small data D (1) (oldest data) is deleted, and the data D (2) to D (R) are shifted to the addresses B (1) to B (R-1) where the address number is decreased by one.

  Then, the data control unit 130A assigns the sequence number p + 1 continuous with the maximum sequence number p assigned to the data stored in the buffer 120 to the new data D (NEW) and also assigns the sequence number p + 1. Data D (NEW) is stored in Rth address B (R) of buffer 120.

  As described above, when new data is generated within the predetermined time T, the data control unit 130A deletes data (the oldest data) to which the smallest sequence number is assigned, and stores the data stored in the buffer 120. Is added to the newly generated data and stored in the Rth address B (R). Thereby, the buffer 120 stores R pieces of data.

  Further, the data control unit 130A determines that when the data stored in the buffer 120 is not full, that is, m pieces of data D (1), D (2), D (3),. When stored in the buffer 120, the m pieces of data D (1), D (2), D (3),... When the data D (NEW) is generated, the data having the smallest sequence number (the oldest data) D (1) is deleted, and the data D (2) to D (m) are addresses whose address numbers are reduced by one. Shift from B (1) to B (R-3).

  Then, the data control unit 130A assigns a sequence number p-R + m + 1 continuous to the maximum sequence number p-R + m assigned to the data stored in the buffer 120 to the new data D (NEW), and also adds a sequence number. Data D (NEW) to which p−R + m + 1 is assigned is stored in the Rth address B (R). That is, when the buffer 120 is not full, the data control unit 130A does not continue the newly generated data D (NEW) with the data D (2) to D (m) already stored in the buffer 120. Store in the Rth address B (R). Thereby, each data can be transmitted R times.

  The data control unit 130A assigns a sequence number to the newly generated data D (NEW) by the two methods described above, and stores the sequence number in the buffer 120. The data control unit 130A then adds data D (2), D (3),..., D (R), D (NEW) or D (2) to which the newly generated data D (NEW) is added. , ..., D (m), D (NEW) are read from the buffer 120, and the read data D (2), D (3), ..., D (R), D (NEW) or D ( 2),..., D (m), D (NEW) are assigned headers to create one packet.

  When the data control unit 130A creates one packet, the data control unit 130A outputs the created one packet to the transmission / reception unit 110, resets the built-in timer, and measures the predetermined time T.

  Further, the data control unit 130A, when new data D (NEW) is not generated within the predetermined time T, the data D (1), D (2),..., D (j ) (J is a natural number satisfying j ≦ R), the data having the smallest sequence number (the oldest data) D (1) is deleted, and the data D (2) to D (j) are assigned the address number 1. Shift to the smaller addresses B (1) to B (R-3).

  Then, the data control unit 130A reads the data data D (2) to D (j) stored in the buffer 120, and adds a header to the read data D (2), ..., D (j). To create one packet.

  When the data control unit 130A creates one packet, the data control unit 130A outputs the created one packet to the transmission / reception unit 110, resets the built-in timer, and measures the predetermined time T.

  In this way, when new data is generated within a predetermined time T, the data control unit 130A deletes the oldest data stored in the buffer 120 regardless of whether the buffer 120 is full or not. The new data is added to the last address B (R) of the buffer 120 and output to the transmission / reception unit 110. In addition, when new data is not generated within the predetermined time T, the data control unit 130 </ b> A deletes the oldest data among the data stored in the buffer 120 and outputs the remaining data to the transmission / reception unit 110.

  FIG. 12 is another flowchart for explaining the operation in transmitter TX shown in FIG. When the operation in the transmitter TX is started, the data generation unit 140 generates new data D (NEW) and outputs the generated data D (NEW) to the data control unit 130A. Then, the data control unit 130A determines whether or not the end command FNH is received (step S31). When the end command FNH is received, the operation in the transmitter TX is ended.

  On the other hand, when the end command FNH is not received, the data control unit 130A initializes the buffer 120 (step S32), and whether or not data is generated depending on whether or not the data D (NEW) is received from the data generation unit 140. Is determined (step S33).

  When the data is generated, the data control unit 130A gives a sequence number to the new data (step S34), and sets the new data to the Rth data in the buffer 120 (step S35). Thereafter, the series of operations proceeds to step S37.

  On the other hand, when it is determined in step S33 that data has not been generated, the data control unit 130A determines whether or not the time measured by the built-in timer has passed a certain time T (step S36), and the certain time. When T has not elapsed, the series of operations proceeds to step S33.

  After step S35 or when it is determined in step S36 that the fixed time T has elapsed, the data control unit 130A determines whether or not the buffer 120 is empty (step S37), and the buffer 120 is empty. At this time, the series of operations proceeds to step S31, and the above-described steps S31 to S35 or step S36 are repeatedly executed.

  When it is determined in step S37 that the buffer 120 is not empty, the data control unit 130A reads the data stored in the buffer 120, adds a header to the read data, creates one packet, and transmits and receives To 110. Then, the transmission / reception unit 110 transmits the packet received from the data control unit 130A to the receiver RX (step S38).

  Thereafter, the data control unit 130A sets a built-in timer and measures a predetermined time T (step S39). Then, the data control unit 130A deletes the data (oldest data) D (1) having the smallest sequence number from the data stored in the buffer 120, and the remaining data D (2) to D (R). D (2) to D (m); D (2) to D (j) are shifted to an address having a smaller address number (step S40). Thereafter, the series of operations proceeds to step S33.

  In the flowchart of steps S33 to S35 and S37 to S40 in the flowchart shown in FIG. 12, when new data is generated within a predetermined time T, the oldest data among the data stored in the buffer 120 is deleted and remains. Is shifted to an address with a smaller address number, and new data is added to the last address (Rth address) of the buffer 120 and transmitted to the receiver RX. In this path, when new data is generated, the oldest data is deleted regardless of whether the buffer 120 is full. New data is always stored at the last address of the buffer 120. Therefore, each data can be transmitted R times.

  In addition, when new data is not generated within a predetermined time T, the path of steps S33 and S36 to S40 deletes the oldest data from the data stored in the buffer 120 and sends the remaining data to the receiver RX. This is the transmission route.

  Further, the path of steps S31, S32, S33, S36, S37, and S31, when the buffer 120 becomes empty, stops transmitting data to the receiver RX and waits, and an end command is issued during the standby. This is a path that ends a series of operations when received.

  Thus, according to the flowchart shown in FIG. 12, each data stored in the buffer 120 can be transmitted R times to the receiver RX.

  Note that the data control unit 130A of the transmitter TX has been described as storing the newly generated data D (NEW) at the last address (Rth address) of the buffer 120. However, in the present invention, the present invention is not limited to this. Alternatively, the newly generated data D (NEW) may be added so as to be continuous with the data D (m) having the maximum sequence number p−R + m stored in the buffer 120 (dotted line shown in FIG. 11). (Refer to data D (NEW) shown in FIG. 4).

  In this case, the newly generated data D (NEW) is transmitted to the receiver RX a number of times equal to the number of data stored in the buffer 120 after adding the new data D (NEW). Since the address at which new data D (NEW) is added varies depending on the number of data stored in buffer 120, new data D (NEW) is added continuously to the data stored in buffer 120. In this case, new data D (NEW) is transmitted to receiver RX generally k times.

  Then, when new data D (NEW) is continuously added to the data stored in the buffer 120, step S35 shown in FIG. 12 indicates that “new data D (NEW) is stored in the buffer 120. Is set to the step of “set to the k-th address consecutive to”.

  When the terminal device 11A shown in FIG. 10 is used as the terminal devices 11 to 1N, the transmitter TX generally receives k pieces of data every predetermined time T or within a predetermined time T as new data D (NEW). By transmitting once every time it is generated, each of the k data is repeatedly transmitted to the receiver RX in the range of k times to R times.

  When each of the terminal devices 11 to 1N is configured from the functional block diagram shown in FIG. 2, the transmitter TX transmits each of k pieces of data R times or more. Therefore, the transmitter TX according to the present invention Each of the k data is transmitted to the receiver RX k times or more by transmitting k data once every predetermined time T or every time new data D (NEW) is generated within the predetermined time T. Send.

  When new data D (NEW) is generated within a predetermined time T, the transmitter TX transmits k data to the receiver RX when the new data D (NEW) is generated. When new data D (NEW) is not generated, the data stored in the buffer 120 is transmitted to the receiver RX when the predetermined time T has elapsed, so that the transmitter TX transmits k data to the receiver RX. The timing to do changes from time to time. That is, the transmitter TX transmits k data to the receiver RX at an arbitrary time.

  The radio communication system 100 according to the present invention is applied, for example, when a plurality of terminal devices gather and perform. That is, the present invention is applied when music is played on a plurality of terminal devices. In this case, the music data needs to be transmitted from each terminal device to another terminal device in real time. Since each terminal performs in accordance with the sound reproduced based on the received music data, the allowable range of the waiting time of each data is in the range of 30 to 40 [msec]. When the waiting time in this range is exceeded, the tempo of the music gradually decreases. The present invention can also be applied to the case where music data is transmitted from a plurality of terminals to one terminal and the music data is played back by the one terminal.

  The wireless communication system 100 according to the present invention is applied when a game is played on one terminal device. In this case, each terminal device transmits data related to the game to one terminal device, and plays against the opponent on one terminal device. Therefore, also in this case, real-time performance is required for data reproduction in one terminal device.

  Furthermore, the wireless communication system 100 according to the present invention is applied to robot control.

  As described above, the wireless communication system 100 according to the present invention can be applied to various cases. In the present invention, which of the unicast communication method and the broadcast communication method is used depends on the required waiting time. Determined. When a shorter waiting time is required, the same data is transmitted R times or more by the above-described method using the broadcast communication method. Further, when a relatively long waiting time is allowed, a unicast communication method can be used.

  Therefore, in the present invention, the communication method is determined according to the required waiting time.

  The radio communication system 100 according to the present invention is characterized in that the same data is transmitted at least as many times as the number R of data stored in the buffer 120. Therefore, in order to reduce the packet error rate, the number R of data constituting one packet may be increased.

  In the above description, it has been described that the predetermined time T is determined by T = D / (n × R). However, the present invention is not limited to this, and the predetermined time T is uniformly determined in all cases. Alternatively, it may be determined according to other rules, or may be determined randomly.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

  The present invention is applied to a wireless communication system capable of suppressing data loss and shortening data waiting time. The present invention is also applied to a program for causing a computer to execute data transmission / reception in a wireless communication system capable of suppressing data loss and shortening the waiting time for wireless communication.

  The present invention is particularly effective in the case where control packets having a very small packet size such as MIDI data are exchanged in real time.

1 is a schematic block diagram of a radio communication system according to an embodiment of the present invention. It is a functional block diagram of the terminal device shown in FIG. It is a packet block diagram. It is a packet block diagram. 3 is a flowchart for explaining an operation in the transmitter shown in FIG. 1. 3 is a flowchart for explaining an operation in the receiver shown in FIG. 1. It is a figure which shows the change of the packet error rate with respect to the number of terminal devices at the time of using broadcast communication. It is a figure which shows the change of waiting time with respect to the number of terminal devices. It is a figure which shows the relationship between the waiting time represented by Formula (1), (2) and (3), and the number of terminal devices. It is another functional block diagram of the terminal device shown in FIG. It is a packet block diagram. 6 is another flowchart for explaining the operation of the transmitter shown in FIG. 1.

Explanation of symbols

  11 to 1N terminal device, 21 to 2N antenna, 30 radio communication space, 100 radio communication system, 110 transceiver unit, 120 buffer, 130, 130A data control unit, 140 data generation unit, 150 data reproduction unit, 160 counter.

Claims (19)

k (k is a natural number satisfying 1 ≦ k ≦ R, R is a natural number of 2 or more) data is transmitted once every arbitrary time, whereby each of the k data is transmitted k times. A transmitter that transmits the above,
A receiver that receives the k data in a wireless communication space and reproduces new data out of the k data ;
The transmitter transmits the k pieces of data once every predetermined time or every time data is generated within the predetermined time according to one of the first and second modes. Each of the data is sent R times or more,
The first mode is a mode in which when new data is generated within the predetermined time, the new data is transmitted in addition to the already transmitted data so as to be generated in the order of generation,
The second mode is a wireless communication system in which when the new data is not generated within the predetermined time, the data held in the transmitter is transmitted when the predetermined time elapses . The first mode is:
When the new data is generated within the predetermined time, the oldest data among the R data is deleted, and the new data is converted into R-1 data that has already been transmitted so as to be generated. A mode for transmitting the added R pieces of data;
2. The wireless communication according to claim 1 , wherein when the new data is generated within the predetermined time, the wireless data communication mode includes a mode in which the new data is transmitted in addition to the already transmitted data in order of generation. system. The transmitter is
A data generation unit for generating data;
A buffer capable of storing the R data;
A transmission unit for transmitting the data;
When new data is generated by the data generation unit within the predetermined time, the k pieces of data are created by adding the new data to the data stored in the buffer so as to be in the generation order, and sent to the transmission unit. outputs, when said new data by the data generating unit is not generated within the predetermined time, the data stored in the buffer is read and a data control unit for outputting to the transmission unit, according to claim 1 Wireless communication system. The data control unit determines whether or not the number of data stored in the buffer is the R data when the new data is generated within the predetermined time, and the data is stored in the buffer. When the number of data is R, the oldest data among the R data is deleted, and the new data is added to R-1 data so as to be generated and sent to the transmitter. The wireless communication system according to claim 3, which outputs the wireless communication system. The data control unit determines whether or not the number of data stored in the buffer is the R data when the new data is generated within the predetermined time, and the data is stored in the buffer. When the number of data is less than the R data, the new data is added to the data stored in the buffer so that the number of data stored in the buffer is in the generation order until the number of data stored in the buffer reaches the R data. The wireless communication system according to claim 3 , wherein the wireless communication system outputs the data to the transmitter . The buffer stores new data sequentially generated in association with sequentially increasing sequence numbers,
When new data is generated by the data generation unit, the data control unit gives the new data a sequence number subsequent to the maximum sequence number used in the buffer, and the buffer is full When the data corresponding to the smallest sequence number is deleted, and the new data is added to the R-1 pieces of data so as to be in the order of the sequence numbers and output to the transmission unit, and the buffer is not full The wireless communication system according to claim 4 , wherein the new data is added so as to be in the order of the sequence numbers and is output to the transmission unit . The data control unit, when the number of times that the new data is not generated within the predetermined time reaches a predetermined number, stops outputting the data stored in the buffer to the transmission unit and waits. The radio | wireless communications system of any one of Claim 3-6 . In the first mode, when the new data is generated within the predetermined time, the oldest data among the k pieces of data is deleted, and the new data is already transmitted so as to be transmitted R times. The wireless communication system according to claim 1 , wherein the wireless communication system is a mode for transmitting the k data added to the transmitted k−1 data . The transmitter repeatedly transmits each of the k data R times by transmitting the k data once every predetermined time or every time data is generated within the predetermined time.
The transmitter is
A data generation unit for generating data;
A buffer capable of storing the R data;
A transmission unit for transmitting the data;
When new data is generated within the predetermined time by the data generation unit, the oldest data among the data stored in the buffer is deleted, and the new data is added to be transmitted R times. Data control that creates and outputs data to the transmission unit, and reads the data stored in the buffer and outputs the data to the transmission unit when the new data is not generated within the predetermined time by the data generation unit The wireless communication system according to claim 1 , further comprising: a unit . The wireless communication system according to claim 9 , wherein when the buffer becomes empty , the data control unit further stops transmission of the k pieces of data and stands by . The buffer has R addresses where the R data can be stored, and stores the k data to which the sequentially increasing sequence numbers are assigned in the generation order, in k addresses,
When new data is generated by the data generation unit, the data control unit assigns a sequence number subsequent to the maximum sequence number used in the buffer to the new data, and the first address of the buffer The data stored in is deleted, the remaining data is shifted to an address with a smaller address number, and the new data is added to the Rth address of the buffer and output to the transmitter. The wireless communication system according to claim 9 or 10 . The data control unit further deletes the data stored in the first address of the buffer when the new data is not generated within the predetermined time, and moves the remaining data to an address having a smaller address number. The radio communication system according to claim 11, wherein the radio communication system shifts, reads out data stored in the buffer, and outputs the data to the transmission unit . A program for causing a computer to execute transmission / reception of data in a wireless communication system including a transmitter and a receiver arranged in a wireless communication space,
k (k is a natural number satisfying 1 ≦ k ≦ R, R is a natural number of 2 or more) data is transmitted once every arbitrary time, whereby each of the k data is transmitted k times. A first step transmitted by the transmitter;
The receiver receives the k pieces of data in the wireless communication space, and causes the computer to execute a second step of reproducing new data out of the k pieces of data;
In the first step, the transmitter transmits each of the k pieces of data by transmitting the k pieces of data once every predetermined time or every time data is generated within the predetermined time. Send more than once,
The first step includes
A first sub-step of generating new data within the predetermined time;
A second sub-step of transmitting the new data in addition to the data stored in the buffer of the transmitter so that the new data is generated within the predetermined time in order of generation;
And a third sub-step for reading and transmitting the data stored in the buffer when the new data is not generated within the predetermined time . The second sub-step includes
Determining whether the number of data stored in the buffer is R when the new data is generated within the predetermined time; and
When the number of data stored in the buffer is R, a step B of deleting the oldest data among the R data;
A program for causing a computer to execute the program according to claim 13 , further comprising a step C of adding the new data to R−1 data so as to be generated and transmitting the R data . The second sub-step includes
The method further comprises a step (D) of transmitting the new data in addition to the data stored in the buffer so as to be generated when the number of data stored in the buffer is less than R. A program to be executed by the computer described in 1. Step D, the number of data stored in the buffer the are repeatedly executed until the R number, program to be executed by the computer according to 請 Motomeko 15. The third sub-step includes
Determining whether the number of times that the new data is not generated within the predetermined time is less than a predetermined number of times;
Reading and transmitting data stored in the buffer when the number of times that the new data is not generated within the predetermined time is less than the predetermined number of times;
17. The method according to any one of claims 13 to 16, further comprising a step of stopping and waiting for transmission of data stored in the buffer when the number of times that the new data is not generated within the predetermined time reaches a predetermined number. A program for causing a computer according to claim 1 to execute. The second sub-step deletes the oldest data stored in the buffer when the new data is generated within the predetermined time, so that the new data is transmitted R times. Send data in addition to the remaining data other than the oldest deleted data,
The third sub-step deletes the oldest data stored in the buffer and transmits remaining data other than the deleted oldest data when the new data is not generated within the predetermined time. A program for causing a computer according to claim 13 to execute the program. 19. The computer-implemented method of claim 18, wherein the first step further comprises a fourth sub-step of stopping and waiting to transmit data stored in the buffer when the transmitter buffer is empty. Program to let you.

Images