JP2005086753A - Packet transmission apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet transmission apparatus transmitting a packet without losing it while ensuring a real time property even if a fault occurs in a packet transmission path. <P>SOLUTION: If a state wherein data are not rightly transmitted is judged, a transmission section 3 resends data which is judged not to be rightly transmitted, and a first signal processing section 4 stores generated data into a storage section 1. If a state wherein data are rightly transmitted is judged, the transmission section 3 transmits data newly generated by the first signal processing section 4 and the data stored in the storage section. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a packet transmission apparatus that transmits predetermined data (for example, a packet), and more particularly, a packet that can be transmitted without losing a packet while ensuring real-time performance even when a failure occurs in a packet transmission path. The present invention relates to a transmission device.

  Conventionally, there is a system in which a packet that could not be transmitted is stored in a storage unit when a communication interruption occurs due to deterioration in transmission path quality or the like, and is retransmitted when communication is recovered.

  As this storage means, if a simple FIFO is provided in the transmission unit and packets are accumulated when communication is cut off, the packets can be transmitted in sequence without being discarded when communication is recovered. In this case, when the transmission path quality is good, it is transmitted in real time without being stored in the storage means.

  Also, by observing the success or failure of packet transmission and selecting a packet in the storage means, the priority of a packet that repeats transmission failure can be lowered.

For example, a packet communication device is known in which, when retransmission is repeated during transmission of a certain packet, the retransmission of the packet is interrupted so that the subsequent packet can be transmitted (for example, see Patent Document 1). .
Japanese Patent Laid-Open No. 10-117213

  As described above, in a system in which a transmission unit is simply provided with a FIFO as storage means, the order in which packets accumulated during communication recovery are stored is stored and transmitted. For this reason, since it takes a certain amount of time to finish transmitting the packets accumulated during the communication cut-off period, it is not possible to return to real-time transmission with a small delay as usual during communication recovery. In particular, in a system with a small allowable delay amount, it takes a long time to return to a desired transmission delay characteristic even if transmission quality is restored. This problem appears particularly when the communication interruption time is long.

  In addition, as in the packet communication device described in Patent Document 1 described above, it is possible to change the order of packets by lowering the priority of packets that are repeatedly retransmitted. It takes a certain amount of time to return to the real-time transmission after processing all the packets stored in.

  The present invention has been made in view of the above problems, and an object of the present invention is to realize a packet communication system that can quickly return to real-time transmission when communication is restored without discarding packets accumulated when communication is cut off. And

  In order to achieve the above object, a transmission apparatus according to a first aspect of the present invention includes a memory unit 1 that stores a packet, a FIFO 2, a transmission unit 3 that transmits a packet read from the FIFO 2 to a packet transmission path, The input data is packetized for transmission, and the transmission packet is written to the memory device or the FIFO depending on whether or not the amount of packets stored in the FIFO 2 is equal to or smaller than a first predetermined amount. A first signal processing unit 4, and a second signal processing unit 5 that reads a packet stored in the memory unit 1 and writes it to the FIFO 2 if the amount of packets stored in the FIFO 2 is equal to or less than a second predetermined amount, A receiving unit 6 that receives an ACK or NACK for the packet transmitted from the transmitting unit 3 and determines the success or failure of the transmission of the packet; A control line 7 for notifying the packet transmission unit, a control line 8 for notifying the first signal processing unit 4 of the amount of packets stored in the FIFO 2, and a second signal processing unit for the amount of packets stored in the FIFO 2 6 and a control line 9 for notifying 6.

  According to the present invention, packets are stored without loss even when communication is interrupted, and immediately after resuming communication, the packetized data is transmitted to the transmission path with higher priority than packets accumulated during the communication disconnection period after canceling communication disconnection. Then, after the communication is resumed, when the communication becomes stable and the accumulated packets are sufficiently small and the real-time packet transmission is not hindered, it is possible to transmit the accumulated packet when the communication is cut off. As a result, without discarding the packet at the time of communication interruption, it returns to the state of transmitting a real-time packet immediately when communication resumes, and the packet accumulated at the time of communication interruption can be transmitted after the communication is stable it can.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing the overall configuration of the packet transmission apparatus according to the first embodiment of this invention.

  The first signal processing unit 4 receives data from a data generation device (not shown), packetizes the received data, and sends the packetized data (packet) to the memory unit 1 or the FIFO 2. The memory unit 1 functions as a storage unit that receives a packet from the first signal processing unit 4 and stores the packet. The FIFO 2 receives packets from the first signal processing unit 4 or the second signal processing unit 5, holds a predetermined number of received packets, and transmits the oldest packet among the held packets to the transmission unit By sending to 3, it functions as a transmission buffer.

  The transmission unit 3 transmits the packet received from the FIFO 2 to a communication partner (not shown) via the packet transmission path. The packet transmission rate of the transmission unit 3 (that is, the packet transmission capability of the packet transmission device of the present invention) is larger than the packet generation rate of the first signal processing unit 4.

  The receiving unit 6 receives a confirmation message (ACK or NACK) as to whether or not the packet has arrived from the packet transmission destination, and determines the state of the packet transmission path depending on whether or not the packet has been correctly transmitted.

  Note that the packet transmission path in the present invention may be any packet transmission / reception, but the present invention is characterized by the operation when a failure occurs in the packet transmission path. This is suitable when using a transmission path in which the communication state is not stable and communication interruption may occur.

  The memory unit 1 temporarily stores the packet received from the first signal processing unit 4 and sends the stored packet to the second signal processing unit 5. The second signal processing unit 5 sends the packet sent from the memory unit 1 to the FIFO 2.

  Further, the receiving unit 6 and the transmitting unit 3 are connected by a control line 7, and the FIFO 2 and the first signal processing unit 4 are connected by a control line 8, and the FIFO 2 and the second signal processing unit. Are connected to each other by a control line 9.

  Next, the operation of the packet transmission apparatus according to the first embodiment configured as described above will be described.

  The first signal processing unit 4 sequentially receives data from a data generation device (not shown), and generates a packet when a certain amount of this data is accumulated.

  Further, the first signal processing unit 4 knows the amount of packets stored in the FIFO 2 through the control line 8. Then, the first signal processing unit 4 writes the packet into the FIFO 2 based on the comparison result between the amount of packets stored in the FIFO 2 and the first predetermined amount (for example, two), or the memory unit 1 Determine whether to write to. That is, if the amount of packets stored in the FIFO 2 is less than or equal to the first predetermined amount, the packets are written into the FIFO 2. On the other hand, if the amount of packets stored in the FIFO 2 is larger than the first predetermined amount, the packets are written in the memory unit 1.

  The second signal processing unit 5 knows the amount of packets stored in the FIFO 2 through the third control line 9. Then, the second signal processing unit 5 reads out the packet stored in the memory unit 1 and writes it in the FIFO 2 based on the comparison result between the amount of packets stored in the FIFO 2 and the second predetermined amount. That is, if the amount of packets stored in the FIFO 2 is equal to or less than the second predetermined amount and the packet is stored in the memory unit 1, the packet stored in the memory unit 1 is read and written to the FIFO 2. . The second predetermined amount is a value smaller than the first predetermined amount and may be “0”.

  The transmission unit 3 reads one by one from the oldest packet stored in the FIFO 2 and transmits it to the packet transmission path. When a communication partner (not shown) correctly receives a packet transmitted from the transmission unit 3, the communication partner notifies the reception unit 6 that the packet has been correctly received by a predetermined signal (ACK). Further, when the communication partner cannot correctly receive the packet, the reception unit 6 is similarly notified by a predetermined signal (NACK).

  The reception unit 6 functions as a determination unit that determines whether the received signal is ACK or NACK and determines whether the packet transmission is correct. At this time, the receiving unit 6 has previously received information on the packet transmitted from the transmitting unit 3 to the packet transmission path from the transmitting unit 3, and receives the ACK or NACK corresponding to the transmitted packet from the transmitting unit 3. It is determined whether or not the transmitted packet is correct, that is, whether or not the packet is correctly transmitted. Then, the receiving unit 6 transmits information on the correctness of packet transmission to the transmitting unit 3 through the control line 7.

  When the packet is correctly transmitted (successful transmission), the transmission unit 3 newly reads the packet stored in the FIFO 2 and transmits the packet to the packet transmission path. When the packet transmission is not performed correctly (transmission fails), the transmission unit 3 does not read the packet from the FIFO 2 and is stored in a cache memory provided in the transmission unit 3 (the cache memory included in the transmission unit 3). Packet) is transmitted again to the packet transmission path.

  Here, the operation of the packet transmission apparatus according to the first embodiment of this invention when the second predetermined amount is set to 0 will be described.

  When communication interruption has not occurred in the packet transmission path, that is, as described above, when the reception unit 6 has received ACK as a result of transmission of the packet by the transmission unit 3, the first signal processing unit The packet generated from the data input to 4 and written in the FIFO 2 is immediately read from the FIFO 2 by the transmission unit 3 and transmitted to the packet transmission path. For this reason, no packets are stored in the FIFO 2, and the data input to the first signal processing unit 4 is sent to the communication partner via the packet transmission path in real time.

  Here, once communication interruption occurs in the packet transmission path, the receiving unit 6 receives NACK. Since the packet is not correctly transmitted to the packet transmission path, the transmission unit 3 repeats the retransmission process of the packet in the cache of the transmission unit 3. In the meantime, since the packet generated by the first signal processing unit 4 is sent to the FIFO 2, if the communication interruption is not solved, untransmitted packets start to be accumulated in the FIFO 2. When the amount of packets in the FIFO 2 exceeds the first predetermined amount, the first signal processing unit 4 knows that the amount of packets in the FIFO 2 has exceeded the first predetermined amount through the control line 8. Then, after the amount of packets accumulated in the FIFO 2 exceeds the first predetermined amount, the first signal processing unit 4 writes the generated packet in the memory unit 1, not in the FIFO 2, and stores it in the memory unit 1. Remember me.

  At this time, the amount of packets stored in the FIFO 2 does not decrease until the communication interruption of the packet transmission path is resolved. Accordingly, since the amount of packets stored in the FIFO 2 does not become the second predetermined amount (“0”) or less, packets written in the memory unit 1 before the communication interruption is canceled Are not written into the FIFO 2 by the signal processing unit 5.

  Eventually, when the communication interruption of the packet transmission path is resolved, the reception unit 6 receives the ACK from the packet reception path, and therefore determines that the packet has been sent correctly, and notifies the transmission unit 3 accordingly. When the transmission unit 3 knows that the packet has been sent correctly, it reads the next packet from the FIFO 2 and transmits it. Then, the amount of packets stored in the FIFO 2 starts to decrease by being read by the transmission unit 3 and transmitted to the packet transmission path.

  While communication is interrupted, the amount of packets stored in the FIFO 2 is always the first predetermined amount because neither transmission nor writing is performed. Here, when the communication interruption is eliminated, the FIFO 2 packet is read and transmitted by the transmission unit 3. When the amount of packets stored in the FIFO 2 is even smaller than the first predetermined amount, the first signal processing unit 4 writes the generated packet directly in the FIFO 2 instead of the memory unit 1.

  When the transmission unit 3 finishes transmitting all the first predetermined amount of packets stored in the FIFO 2, the state returns to a state in which packets are transmitted in real time (real time communication). During this time, the first signal processing unit 4 writes the generated packet in the FIFO 2 because the amount of packets stored in the FIFO 2 is smaller than the first predetermined amount.

  Then, when the amount of packets accumulated in the FIFO 2 further decreases to a second predetermined amount (that is, 0), the second signal processing unit 5 stores the accumulated packets stored in the memory unit 1 into the FIFO 2. Write. Since the transmission unit 3 sequentially transmits the packets written in the FIFO 2 from the first signal processing unit 4 or the second signal processing unit 5 to the packet transmission path from the oldest packet, it transmits the packets in real time. At the same time, the packet stored in the memory unit 1 is also transmitted. Thereby, it is possible to transmit packets without losing packets accumulated at the time of communication interruption while ensuring the real-time property of packet transmission.

  Each packet is given a time stamp, a series of numbers, and the like. In addition, a predetermined flag is attached to the packet once accumulated in the memory unit 1. Therefore, the communication partner receiving the packet can identify whether the packet is a real-time packet or a packet once accumulated in the memory unit 1 due to communication interruption or the like by determining the order of the packets.

  As described above, when communication interruption occurs in the packet transmission path, the packet generated by the first signal processing unit 4 is stored in the memory unit 1, and after the communication interruption is recovered, the first signal processing is performed. The packet generated by the unit 4 can be transmitted to the packet transmission path in real time. At this time, the second signal processing unit 5 transmits the packet written in the FIFO 2 only when the packet is not accumulated in the FIFO 2 (that is, the packet written in the FIFO 2 is further transmitted by the first signal processing unit 4). Only when the new packet is not written in the FIFO 2), since the packet stored in the memory unit 1 is written in the FIFO 2, the real-time property of transmission of the packet generated after the communication interruption is recovered is ensured.

  Next, the operation of the packet transmission apparatus according to the first embodiment of the present invention when the second predetermined amount is set larger than “0” will be described.

  In particular, when the above-mentioned second predetermined amount is set to “0”, when the data is sequentially input to the first signal processing unit 4 and the packet is always written in the FIFO 2, the communication interruption is resolved. However, there is a case where the amount of the FIFO2 packet does not become zero, and the packet stored in the memory unit 1 may not be transmitted by the transmission unit 3 indefinitely. When the second predetermined amount is set larger than “0”, the packet stored in the memory unit 1 can be transmitted by the transmission unit 3 even in such a case.

  Similarly to the case where the second predetermined amount is 0 as described above, when communication is not interrupted in the packet transmission path, no data is stored in the FIFO 2, so the data input to the first signal processing unit 4. The generated packet is directly written into the FIFO 2, read out from the FIFO 2 by the transmission unit 3 from the FIFO 2, and transmitted to the packet transmission path. For this reason, no packets are stored in the FIFO 2, and the data input to the first signal processing unit 4 is sent to the communication partner via the packet transmission path in real time.

  Here, once communication interruption occurs in the packet transmission path, the receiving unit 6 receives NACK. Since the packet is not correctly transmitted to the packet transmission path, the transmission unit 3 repeats the retransmission process of the packet in the cache of the transmission unit 3. In the meantime, since the packet generated by the first signal processing unit 4 is sent to the FIFO 2, if the communication interruption is not solved, untransmitted packets start to be accumulated in the FIFO 2. When the amount of packets in the FIFO 2 exceeds the first predetermined amount, the first signal processing unit 4 knows that the amount of packets in the FIFO 2 has exceeded the first predetermined amount through the control line 8. Then, after the amount of packets accumulated in the FIFO 2 exceeds the first predetermined amount, the first signal processing unit 4 writes the generated packet in the memory unit 1 instead of the FIFO 2.

  That is, when the NACK is received, it is determined that the data is not correctly transmitted, and the first signal processing unit 4 is triggered by the amount of packets in the FIFO 2 exceeding the first predetermined amount. The generated packet is stored in the memory unit 1.

  At this time, the amount of packets stored in the FIFO 2 does not decrease until the communication interruption of the packet transmission path is resolved. Accordingly, since the amount of packets stored in the FIFO 2 does not become the second predetermined amount (“0”) or less, packets written in the memory unit 1 before the communication interruption is canceled Are not written into the FIFO 2 by the signal processing unit 5.

  Eventually, when the communication interruption of the packet transmission path is resolved, the reception unit 6 receives the ACK from the packet reception path, and therefore determines that the packet has been sent correctly, and notifies the transmission unit 3 accordingly. When the transmission unit 3 knows that the packet has been sent correctly, it reads the next packet from the FIFO 2 and transmits it. Then, the amount of packets stored in the FIFO 2 starts to decrease by being read by the transmission unit 3 and transmitted to the packet transmission path.

  While communication is interrupted, the amount of packets stored in the FIFO 2 is always the first predetermined amount because neither transmission nor writing is performed. When the communication interruption is resolved, the FIFO 2 packet is read out and transmitted by the transmission unit 3. When the amount of packets stored in the FIFO 2 is even smaller than the first predetermined amount, the first signal processing unit 4 writes the generated packet directly in the FIFO 2 instead of the memory unit 1.

  When the packet amount stored in the FIFO 2 further decreases and becomes smaller than the second predetermined amount, the second signal processing unit writes the packet stored in the memory unit 1 into the FIFO 2. Since the transmission unit 3 sequentially transmits the packets written in the FIFO 2 from the first signal processing unit 4 or the second signal processing unit 5 to the packet transmission path from the oldest packet, it transmits the packets in real time. At the same time, the packet stored in the memory unit 1 is also transmitted. Thereby, it is possible to transmit packets without losing packets accumulated at the time of communication interruption while ensuring the real-time property of packet transmission.

  That is, by receiving the ACK, it is determined that the data is correctly transmitted, and further, when the amount of packets in the FIFO 2 becomes smaller than the second predetermined amount, the transmission unit 3 1 signal processing unit 4 transmits a newly generated packet and a packet stored in memory unit 1.

  In this case, the packet stored in the memory unit 1 at the time of communication interruption may be transmitted before the packet generated by the first signal processing unit 4 after recovery of communication interruption, but the packet is given a time stamp or the like. Therefore, it is possible to identify whether the transmission unit 3 and the communication partner are real-time packets or packets that are temporarily stored in the memory unit 1 due to communication interruption or the like. Whether the transmission unit 3 and the communication partner are data stored in the memory unit 1 by adding a flag to the data stored in the memory unit 1 (or data not held in the memory unit 1). Whether or not can be identified.

  As described above, when communication interruption occurs in the packet transmission path, the packet generated by the first signal processing unit 4 is stored in the memory unit 1, and after the communication interruption is recovered, the first signal processing is performed. The packet generated by the unit 4 can be transmitted to the packet transmission path in real time. At this time, since the second signal processing unit 5 writes the packet stored in the memory unit 1 to the FIFO 2 only when the amount of packets stored in the FIFO 2 is smaller than the second predetermined amount, the communication interruption is recovered. Then, after returning to a state where real-time transmission is possible, the packets stored in the memory unit 1 can be efficiently transmitted when communication is interrupted.

  Next, a packet transmission apparatus according to the second embodiment of this invention will be described.

  The packet transmission apparatus according to the second embodiment realizes the operation of the packet transmission apparatus according to the first embodiment by software. In addition, the same code | symbol is attached | subjected to the structure which carries out the same operation | movement as 1st Embodiment, and the description is abbreviate | omitted.

  FIG. 2 is a block diagram illustrating a configuration of the packet transmission apparatus according to the second embodiment.

  The processor 10 receives data from a data generation device (not shown), packetizes the data, and sends it to the transmission unit 3.

  The processor 10 stores the generated packets by dividing them into two types of “1 type stored packet” that requires real time transmission and “2 type stored packet” that does not require real time transmission. Each packet is stored such that the packet type can be determined together with the generation time and the generation order. Further, the processor 10 changes the packet generation and storage operation depending on the storage amount of the one type of accumulated packet. As the reference, first and second predetermined amounts are set. The second predetermined amount may be smaller than the first predetermined amount, and the second predetermined amount may be zero.

  Next, the operation of the packet transmission apparatus according to the second embodiment will be described.

  The operation of the packet transmission apparatus according to the second embodiment is a packetization process that is performed when data sequentially input is accumulated for one packet, and the accumulated amount of the one-type accumulated packet exceeds the second predetermined amount. It can be broadly divided into three types: packet type change processing that is sometimes performed, and packet transmission processing for transmitting packets.

  The processor 10 generates a packet when one packet of input data sequentially input to the packet transmission device is accumulated. Then, the type of the packet is determined and the generated packet is stored. That is, when the accumulated amount of packets at that time does not exceed the first predetermined amount, it is stored as one type of accumulated packet, and when the accumulated amount of packets is equal to or more than the first predetermined amount, it is stored as two types of accumulated packets. .

  If the accumulated amount of the one type of accumulated packet is smaller than the second predetermined amount, the oldest one is extracted from the two types of accumulated packets, the packet type is changed, and the accumulation time is changed to the current time (type) At the time of change) and newly stored as a one-type accumulated packet.

  Next, the one-type stored packet stored in the processor 10 is sent from the transmitter 3 to the packet receiving side via the packet transmission path. When the processor 10 receives a notification from the receiving unit 6 that it has received an ACK for the transmitted packet, the processor 10 deletes the last transmitted packet as transmitted, and the processor 10 deletes the oldest one of the one kind of accumulated packets. One is read and sent to the transmitter 3 as the next transmission packet.

  On the other hand, when the notification that the reception unit 6 has received the NACK is received, the processor 10 does not delete the last transmitted packet as a transmission failure, and the last transmitted packet is transmitted to the transmission unit 3 as the next transmission packet. Send again. Then, the transmission unit 3 transmits the packet set by the processor 10.

  FIG. 3 is a flowchart illustrating processing of the packet transmission device according to the second embodiment.

  Data is sequentially input to the processor 10 from a data generation device (not shown). Then, it is determined whether or not a certain amount of this data has been accumulated (that is, one packet) (process 1001). When data for one packet is not accumulated, the process proceeds to step S1003, and this process is repeated until data for one packet is accumulated. If it is determined that one packet of data has been accumulated, the processing proceeds to processing 1002.

  In the process 1002, a packetization process (FIG. 4) for generating a packet from the accumulated data is performed. In this packetization process, the generated packet is stored as a one-type stored packet or a two-type stored packet according to the amount of packets stored in the processor 10.

  Next, it is determined whether or not the amount of the one-type stored packet stored in the processor 10 is equal to or greater than a second predetermined amount (process 1003). If the accumulated amount of the one-type accumulated packet is smaller than the second predetermined amount, the process proceeds to process 1004, and if it is greater than or equal to the second predetermined amount, the process proceeds to process 1005 without performing process 1004.

  In process 1004, a packet type change process (FIG. 5) is performed in which the one-type stored packet stored in the processor 10 is changed to a two-type stored packet.

  In the process 1005, the oldest packet of the one kind of accumulated packets accumulated in the processor 10 is sent to the transmitting unit 3 and a packet transmission process (FIG. 6) for transmitting to the packet transmission path is performed.

  FIG. 4 is a flowchart showing details of the packetization processing (processing 1002 in FIG. 3) performed by the processor 10.

  The processor 10 generates a packet from the accumulated data when a certain amount of sequentially input data is accumulated (for one packet) (processing 2001).

  Next, it is determined whether or not the amount of the one type of accumulated packet among the packets accumulated in the processor 10 is larger than a first predetermined amount (for example, 2) (process 2002). If it is larger than the first predetermined amount, the process proceeds to processing 2003, and the generated packet is stored as two types of accumulated packets. On the other hand, if it is equal to or less than the first predetermined amount, the process proceeds to processing 2004, and the generated packet is stored as a one-type accumulated packet.

  FIG. 5 is a flowchart showing details of the packet type change process (process 1004 in FIG. 3) performed by the processor 10.

  The processor 10 extracts the oldest of the two types of stored packets, that is, the oldest information of the storage time attached to the two types of stored packets from the stored packets (processing 3001).

  Next, the storage time of the extracted two kinds of accumulated packets is updated to the current time, and the one kind of accumulated packets is changed and stored (process 3002).

  In this way, when the amount of the one type of accumulated packet is smaller than the first predetermined amount, the already accumulated two types of accumulated packet are changed to the one type of accumulated packet. It can send to the transmission part 3 and can transmit to a packet transmission path.

  FIG. 6 is a flowchart showing details of the packet transmission process (process 1005 in FIG. 3).

  The processor 10 extracts and reads out the oldest one of the one kind of accumulated packets, and sends it to the transmitter 3 (process 4001).

  The transmission unit 3 transmits the packet received from the processor 10 to the packet transmission path (process 4002).

  Next, the receiving unit 6 determines whether ACK or NACK has been sent to the packet transmitted by the transmitting unit 3 (process 4003). If NACK is sent, it is determined that the packet is not normally transmitted, the packet already read in the process 4001 is sent again to the transmission unit 3, and the packet is retransmitted (process 4002, 4003).

  On the other hand, if the receiving unit 6 determines that an ACK has been sent, the processor 10 deletes the packet sent to the sending unit (process 4004), ends this flowchart, and returns to the flowchart of FIG. To do.

  According to the above processing, when communication interruption has not occurred in the packet transmission path, the reception unit 6 receives an ACK for the packet transmitted by the transmission unit 3. Therefore, the packets are transmitted sequentially. Packets generated from data sequentially input to the processor 10 are stored as one kind of accumulated packets, and are sequentially transmitted in real time from the oldest one.

  However, once communication interruption occurs in the packet transmission path, the receiving unit 6 receives the NACK, so the processor 10 sends the packet previously sent to the sending unit 3 to the sending unit 3 again. The transmission unit 3 performs processing for retransmitting this packet. For this reason, the oldest one kind of accumulated packet accumulated in the processor 10 is not deleted, and the amount of the one kind accumulated packet starts to increase. When the amount of the one type of accumulated packet exceeds the first predetermined amount, the processor 10 stores the generated packet as the two types of accumulated packet. The generated packet is stored as a two-type stored packet until the communication interruption is resolved and the amount of the one-type stored packet is smaller than the first predetermined amount.

  When the communication interruption of the packet transmission path is resolved, the receiving unit 6 receives ACK. Then, the transmission unit 3 newly reads one type of accumulated packet. In the processor 10, the one-type stored packet for which ACK has been confirmed is deleted, and the amount of the one-type stored packet starts to decrease. When the amount of the one type of accumulated packet becomes smaller than the first predetermined amount, the processor 10 stores a packet generated thereafter as the one type of accumulated packet. This type 1 accumulation packet is transmitted with priority over the type 2 accumulation packet generated and accumulated during the communication cut-off period.

  Eventually, when the type 1 accumulation packet generated before the cancellation of communication interruption is transmitted and the amount of the type 1 accumulation packet is reduced, the packet transmission state returns to a real-time packet transmission state with little delay.

  When the amount of the one type of accumulated packet further decreases and becomes smaller than the second predetermined amount, the packet generated during the communication interruption and stored as the two types of accumulated packet is changed to one type by the packet type changing process (FIG. 5). It is stored again as a stored packet. Since the type 1 accumulation packet is read and transmitted by the transmission unit 3 in the order of accumulation time, the packet stored as the type 2 accumulation packet during communication interruption is not lost, and can be transmitted to the packet transmission path after the communication interruption is canceled. it can.

  The present invention is used in a data transfer apparatus that transmits input data in real time and transmits the input data to a transmission partner without losing the data when communication is interrupted. In particular, it is suitable for medical devices that use wireless communication in the transmission path.

It is a block diagram which shows the whole structure of the packet transmission apparatus of the 1st Embodiment of this invention. It is a block diagram which shows the structure of the packet transmitter of the 2nd Embodiment of this invention. It is a flowchart which shows the process of the packet transmission apparatus of the 2nd Embodiment of this invention. It is a flowchart which shows the detail of the packetization process which the processor 10 of the 2nd Embodiment of this invention performs. It is a flowchart which shows the detail of the packet type change process which the processor 10 of the 2nd Embodiment of this invention performs. It is a flowchart which shows the detail of the packet transmission process which the packet transmission apparatus of the 2nd Embodiment of this invention performs.

Explanation of symbols

1 Memory device 2 FIFO
DESCRIPTION OF SYMBOLS 3 Packet transmission part 4 1st signal processing part 5 2nd signal processing part 6 Reception part 7, 8, 9 Control line 10 Processor

Claims (11)

A first signal processing unit for generating data;
A transmission unit for transmitting data generated by the first signal processing unit;
A determination unit that determines the state of the transmission path according to whether the data transmitted by the transmission unit is correctly transmitted; and
A storage unit for storing data generated by the first signal processing unit;
In a data transmission device comprising:
When it is determined that the data is not correctly transmitted, the transmission unit retransmits the data determined not to be transmitted correctly, and the first signal processing unit stores the generated data in the storage Remember in the department,
When it is determined that the data is correctly transmitted, the transmission unit transmits the data newly generated by the first signal processing unit and the data stored in the storage unit. A data transmission device. A first signal processing unit for generating data;
A transmission buffer for storing data generated by the first signal processing unit;
A transmission unit for transmitting data stored in the transmission buffer;
A determination unit for determining whether or not the data transmitted by the transmission unit is correctly transmitted;
A storage unit for storing data generated by the first signal processing unit;
A second signal processing unit for transferring data stored in the storage unit to the transmission buffer;
In a data transmission device comprising:
When the determination unit determines that the data has been transmitted correctly, the transmission unit reads the data from the transmission buffer and transmits the data, and when the determination unit determines that the data has not been transmitted correctly Retransmits data that was determined not to be sent correctly,
The first signal processing unit stores the generated data in the transmission buffer based on a comparison result between the data amount stored in the transmission buffer and a first predetermined amount, or stores the generated data in the storage unit. Decide whether to remember,
Whether the second signal processing unit transfers the data stored in the storage unit to the transmission buffer based on a comparison result between the data amount stored in the transmission buffer and a second predetermined amount A data transmitting apparatus characterized by determining whether or not. The second predetermined amount is zero;
The data transmission according to claim 2, wherein the second signal processing unit stores the data stored in the storage unit in the transmission buffer when the data is not stored in the transmission buffer. apparatus.   The transmission unit transmits the data stored in the transmission buffer by the first signal processing unit and the data transferred from the storage unit to the transmission buffer by the second signal processing device. Or the data transmission device according to 3;   Whether at least one of the data stored in the storage unit or the data not stored in the storage unit is a data stored in the storage unit by adding a predetermined flag to the data. 5. The data transmission device according to claim 2, wherein it is possible to identify whether or not.   The serial number is added to the data generated by the first signal processing unit, so that the transmission unit can identify the order of the data. The data transmission device according to one. A data transmission method used in a data transmission apparatus, comprising: a processor that generates data and stores the data as first data or second data; and a transmission unit that transmits data generated by the processor. There,
A first procedure for determining whether or not the data transmitted by the transmission unit has been transmitted correctly;
Whether the data generated by the processor is stored as first data or second data based on a comparison result between the generated first data amount and a first predetermined amount A second procedure to determine;
Third procedure for determining whether or not to change the stored second data to the first data based on the comparison result between the amount of the first data and the second predetermined amount. A data transmission method comprising: The processor is
If it is determined that the data has been transmitted correctly by the first procedure, the first data is sent to the transmitter,
8. The data according to claim 7, further comprising: a fourth procedure for retransmitting data determined not to be transmitted correctly when it is determined that the data has not been transmitted correctly by the first procedure. Transmission method. The second predetermined amount is zero;
The data according to claim 7 or 8, wherein the third procedure changes the second data to the first data and stores the first data when the first data is not stored. Transmission method.   A predetermined flag is added to at least one of data stored as the second data or data not stored as the second data, so that the transmission unit stores the data as the second data. 10. The data transmission device according to claim 7, wherein it is possible to identify whether the received data is received data.   The data transmission according to any one of claims 7 to 9, wherein the transmission unit can identify the order of the data by adding a serial number to the data generated by the processor. apparatus.

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