JP2006304138A - Selective retransmission type communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform retransmission processing according to the importance of data in a layer lower than a session layer. <P>SOLUTION: This communication device has transmitting equipment provided with a compression means which compresses media data and outputs the compressed data and outputs an importance identifying signal representing the importance of the compressed data, and a packet transmitting means for generating and outputting a packet to be composed by adding an importance identifying signal to the compressed data; and receiving equipment provided with a packet termination means which receives the packet transmitted from the transmitting equipment and transmits an acknowledgement signal representing a packet not received normally, and a restoration means for restoring the compressed data from a normally received packet. The transmitting equipment is so configured as to recognize the packet not received normally from the acknowledgement signal transmitted from the receiving equipment, and perform retransmission processing of a packet having high importance on the basis of the importance identifying signal added to the packet. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a selective retransmission type communication device related to retransmission processing of a lost packet when media data is compressed and packetized in a streaming data distribution system for audio or moving image media data.

  In a system that distributes audio or moving image media data over a network, the media data may be compressed to save bandwidth. The technique of inter-frame compression is often used for moving images. In this technique, a changed or moved portion is transmitted as an intermediate frame (P picture, B picture) between complete frames (I pictures) that are independently encoded and decoded without depending on the preceding and following frames. Is. In this case, since the data of each frame is not mutually independent, the lack of one data (particularly I picture) deteriorates the quality of the reproduced media data thereafter.

  One effective means for data loss is data retransmission processing. As a specific data retransmission method, retransmission by MAC (Media Access Control) in IEEE802.11 series (wireless LAN) is generally used in the data link layer, and retransmission by TCP (Transmission Control Protocol) is generally used in the transport layer. However, since these retransmission processes are performed uniformly regardless of the contents of the data, the reachability of data can be ensured even in a network with many data loss, but efficient transmission is difficult due to the frequent occurrence of retransmission processes. .

On the other hand, a method of introducing a NACK (Negative Acknowledgment) packet or an ACK (Positive Acknowledgment) packet into RTCP (RTP (Real-time Transport Protocol) control protocol) and performing a retransmission process at the session layer based on this is considered. (Non-Patent Document 1).
Colin Perkins, "Mastering TCP / IP RTP", pp.234-238

  When NACK packets or ACK packets are used and retransmission processing is performed in the session layer, retransmission according to the importance of data and error correction technology is possible. However, since retransmission processing is performed in an upper layer, high-speed data There is a problem that it becomes difficult to deal with.

  An object of the present invention is to provide a selective retransmission type communication apparatus capable of performing retransmission processing according to the importance of data in a lower layer than the session layer.

  The selective retransmission type communication apparatus of the present invention compresses and outputs media data, and outputs a significance identifying signal indicating the significance of the compressed data, and a significance identifying signal for the compressed data. A transmission device comprising a packet transmission means for generating and transmitting the added packet; a packet termination means for receiving a packet transmitted from the transmission device and transmitting a response signal indicating a packet that was not normally received; A receiving device having a restoring means for restoring compressed data from a normally received packet, and the transmitting device recognizes a packet that has not been normally received by a response signal transmitted from the receiving device. The configuration is such that retransmission processing of a packet with high importance is performed based on the importance identification signal added to the packet.

  Here, the packet transmission means may be configured to add the importance level identification signal to the header of the data link layer packet. Further, the packet transmission means may be configured to add the importance level identification signal to the header of the transport layer packet.

  The selective retransmission type communication apparatus of the present invention compresses and outputs media data, and also generates a packet from the compressed data, compression means for outputting an importance level identifying signal indicating the importance level of the compressed data, A transmission device comprising a packet transmission means for transmitting, a packet termination means for receiving a packet transmitted from the transmission device and transmitting a response signal indicating a packet that has not been normally received, and a packet received normally A receiving device having a restoring means for restoring the compressed data, and the transmitting device maintains a correspondence relationship between the transmitted packet and the importance level identification signal, and is normally operated by a response signal transmitted from the receiving device. In this configuration, a packet that has not been received is recognized, the importance level of the packet is determined based on the correspondence relationship, and retransmission processing of the packet with a high importance level is performed.

  The selective retransmission type communication apparatus of the present invention compresses and outputs media data, and outputs a significance identifying signal indicating the significance of the compressed data, and a significance identifying signal for the compressed data. A transmission apparatus comprising: a packet transmission unit that generates and transmits an added packet; and an error correction packet transmission unit that transmits an error correction packet for repairing a packet that is not normally received on the reception side; A packet termination unit that receives a packet transmitted from a transmission device and transmits a response signal indicating a packet that has not been normally received; and an error correction that uses an error correction packet to repair a packet that has not been received normally Means and a receiving device comprising a restoring means for restoring compressed data from a normally received packet, wherein the transmitting device is a receiving device Recognizing a packet that was not normally received by the transmitted response signal, and determining that the packet cannot be repaired beyond the repair capability of the error correction packet, and the importance identification signal added to the packet This is a configuration for performing retransmission processing of packets with high importance based on the above.

  Here, the packet transmission means may be configured to add the importance level identification signal to the header of the data link layer packet. Further, the packet transmission means may be configured to add the importance level identification signal to the header of the transport layer packet.

  The selective retransmission type communication apparatus of the present invention compresses and outputs media data, and also generates a packet from the compressed data, compression means for outputting an importance level identifying signal indicating the importance level of the compressed data, A transmission device comprising: a packet transmission means for transmitting; and an error correction packet transmission means for transmitting an error correction packet for repairing a packet that has not been normally received on the reception side; Packet termination means for receiving a packet and transmitting a response signal indicating a packet that has not been normally received, error correction means for repairing a packet that has not been normally received using an error correction packet, and normal reception And a receiving device having a restoring means for restoring the compressed data from the received packet, and the transmitting device transmits the transmitted packet and the importance identification signal. Recognizing a packet that has not been properly received by the response signal transmitted from the receiving apparatus, and that is determined to be impossible to repair beyond the repair capability of the error correction packet, and the packet Is determined based on the correspondence, and retransmission processing of packets with high importance is performed.

  The present invention can determine whether or not to perform retransmission when a packet is lost according to the importance level identification signal added to the header of the packet. That is, retransmission processing according to the importance of data can be performed in a layer lower than the session layer. As a result, it is possible to guarantee the arrival of important data and to perform efficient transmission.

(First embodiment)
FIG. 1 shows a first embodiment of a selective retransmission communication apparatus of the present invention. FIG. 2 shows a packet configuration of each part of the first embodiment.

  In FIG. 1, a transmission apparatus 10A of a selective retransmission communication apparatus inputs a frame of media data to an encoder 11 and compresses it, and outputs a compressed frame and an importance level identification signal. Here, for example, the importance level identification signal for data with high importance such as an I picture is “1”, and the importance level identification signal for other data is “0”. The compressed frame is input to the session layer packet assembling unit 12 and divided into an appropriate size, and an RTP packet (FIG. 2) is added by adding a RTP header consisting of a payload header specific to the encoding method, a sequence number, a time stamp, and the like. (See (1)) is generated.

  The RTP packet output from the session layer packet assembling unit 12 is input into the transport layer packet assembling unit 14, and a UDP (User Datagram Protocol) header including a destination port number, a transmission source port number, and the like is added to the UDP packet ( FIG. 2 (2)) is generated. The UDP packet output from the transport layer packet assembling unit 14 is input into the network layer packet assembling unit 15, and an IP (Internet Protocol) header including a destination address, a source address, and the like is added to the IP packet (FIG. 2 ( 3) is generated. The IP packet output from the network layer packet assembling unit 15 is input to the data link layer packet assembling unit 16, and a MAC header including a destination address, a source address, an importance level identification signal from the encoder 11, a sequence number, and the like is added. Thus, a MAC packet (see FIG. 2 (4)) is generated. The MAC packet output from the data link layer packet assembling unit 16 is added to the physical layer packet transmitting unit 17 with a physical layer header and transmitted to the receiving device 20A.

  The receiving device 20A of the selective retransmission communication device receives the signal transmitted from the transmitting device 10A by the physical layer packet receiving unit 21, removes the physical layer header, and extracts the MAC packet. The MAC packet output from the physical layer packet receiving unit 21 is input to the data link layer packet terminating unit 22, and the IP header is extracted by removing the MAC header. The IP packet output from the data link layer packet termination unit 22 is input to the network layer packet termination unit 23, and the IP header is removed to extract the UDP packet. The UDP packet output from the network layer packet terminal unit 23 is input to the transport layer packet terminal unit 24, and the UDP header is removed to extract the RTP packet. The RTP packet output from the transport layer packet termination unit 24 is input to the session layer packet termination unit 26, and the RTP header is removed to reconstruct the compressed frame. The compressed frame output from the session layer packet termination unit 26 is input to the decoder 27 and restored to the original media data.

  3 and 4 show an example of a packet retransmission procedure in the first embodiment. The transmitting apparatus 10A accumulates a plurality of packets to be transmitted in the buffer of the data link layer packet assembling unit 16, and creates an importance level table of these packets based on the importance level identification signal output from the encoder 11. After the negotiation is established with the receiving device 20A, packets in the buffer (8 packets in FIGS. 3 and 4) are continuously transmitted, and then a block ACK request signal is transmitted.

  The data link layer packet termination unit 22 of the receiving device 20A returns a list of normally received packets as a block ACK to the transmitting device 10A. The data link layer packet assembling unit 16 of the transmitting apparatus 10A receives the block ACK and determines retransmission processing. That is, the importance level table is compared with the list in the block ACK, and the importance level of the packet that has not been normally received is confirmed. Or you may confirm the importance from the importance identification signal added to the header of the packet which was not received normally.

  Here, when all the packets have been normally received, a transfer completion notification is transmitted to the receiving device 20A, and after the ACK is returned from the receiving device 20A, the packet in the buffer is deleted and the next packet transfer is performed. Start.

  In addition, when there is a packet that has not been received normally but a packet with high importance is not included, in the example illustrated in FIG. 3, when the importance of packet 2 that has not been received normally is low, retransmission processing is not performed. Then, after a transfer completion notification is transmitted to the receiving device 20A and an ACK is returned from the receiving device 20A, the packet in the buffer is deleted and the next packet transfer is started.

  In addition, when there is a packet that has not been normally received and a packet having high importance is included, in the example illustrated in FIG. 4, when the importance of the packet 4 that has not been normally received is high, retransmission processing is performed. Do. The transmitting apparatus 10A retransmits the packet 4, transmits a transfer completion notification after the ACK for the packet 4 is returned from the receiving apparatus 20A, and deletes the packet in the buffer after the ACK is returned from the receiving apparatus 20A. Start the next packet transfer. When the number of retransmissions reaches a predetermined number, a transfer completion notification is transmitted without performing the next retransmission, and after the ACK is returned from the receiving apparatus 20A, the packet in the buffer is deleted and the next packet transfer is performed. To start.

  In the present embodiment, the importance is binary, “1” or “0”, but the importance is multivalued (for example, “2” for I picture, “1” for P picture, “0” for B picture) ) And a different maximum number of retransmissions may be set for each importance. This multi-valued importance is the same in the embodiments described below.

(Second Embodiment)
FIG. 5 shows a second embodiment of the selective retransmission communication device of the present invention. FIG. 6 shows a packet configuration of each part of the second embodiment.

  In FIG. 5, a transmission apparatus 10B of a selective retransmission communication apparatus inputs a frame of media data to an encoder 11 and compresses it, and outputs a compressed frame and an importance level identification signal. Here, for example, the importance level identification signal for data with high importance such as an I picture is “1”, and the importance level identification signal for other data is “0”. The compressed frame is input to the session layer packet assembling unit 12 and divided into an appropriate size, and an RTP packet (FIG. 6) is added with a payload header specific to the encoding method, an RTP header consisting of a sequence number, a time stamp, and the like. (See (1)) is generated.

  The RTP packet output from the session layer packet assembling unit 12 is input into the transport layer packet assembling unit 14, and includes a destination port number, a transmission source port number, an importance level identification signal from the encoder 11, a sequence number, and the like. By adding a layer header (hereinafter referred to as “L4 header”), a transport layer packet (hereinafter referred to as “L4 packet”, see FIG. 6 (2)) is generated. The L4 packet output from the transport layer packet assembly unit 14 is input to the network layer packet assembly unit 15, and an IP packet is added with an IP header composed of a destination address, a source address, and others (see FIG. 6 (3)). Is generated. The IP packet output from the network layer packet assembly unit 15 is transmitted to the receiving device 20B via the IP network 30 (general LAN / WAN) by an appropriate medium.

  The receiving device 20B of the selective retransmission communication device receives the IP packet transmitted from the transmitting device 10B via the IP network 30 by the network layer packet terminal unit 23, removes the IP header, and extracts the L4 packet. The L4 packet output from the network layer packet termination unit 23 is input to the transport layer packet termination unit 24, and the L4 header is removed to extract the RTP packet. The RTP packet output from the transport layer packet termination unit 24 is input to the session layer packet termination unit 26, and the RTP header is removed to reconstruct the compressed frame. The compressed frame output from the session layer packet termination unit 26 is input to the decoder 27 and restored to the original media data.

  7 and 8 show an example of a packet retransmission procedure in the second embodiment. The transport layer packet assembly unit 14 of the transmission apparatus 10B creates a packet importance table based on the importance identification signal output from the encoder 11, and the network layer packet assembly unit 15 converts the packet into an IP packet and transmits it.

  The transport layer packet termination unit 11 of the receiving device 20B confirms the sequence number in the L4 header of the received L4 packet. If the sequence number is continuous, the transport layer packet termination unit 11 determines that it has been received normally and does not respond. On the other hand, if the sequence number jumps, it is determined that the packet is missing, and a NACK is returned to the transmitting apparatus 10B. The transport layer packet assembling unit 14 of the transmitting apparatus 10B receives NACK and makes a retransmission process determination. That is, the importance level of the lost packet notified by NACK is confirmed with reference to the importance level table. Alternatively, the importance level may be confirmed from the importance level identification signal added to the header of the missing packet.

  Here, when all the packets have been normally received (when the sequence numbers are consecutive), the receiving device 20B does not send back a NACK, and therefore the transmitting device 10B does not perform a retransmission process.

  Also, as shown in FIG. 7, when the packet 2 is lost and the packet 3 is received, the sequence number jumps, so the receiving device 20B returns a NACK to the transmitting device 10B. When receiving the NACK, the transmitting apparatus 10B refers to the importance table and confirms the importance of the missing packet 2 notified by NACK. Since the importance of the packet 2 is low, retransmission processing is not performed.

  Also, as shown in FIG. 8, when the packet 4 is lost and the packet 5 is received, the sequence number jumps, so the receiving device 20B returns a NACK to the transmitting device 10B. When receiving the NACK, the transmitting apparatus 10B checks the importance of the missing packet 4 notified by NACK with reference to the importance table. Since the importance of this packet 4 is high, retransmission processing is performed.

  Here, it has been described that NACK is returned as soon as the sequence number jumps. However, in an actual network, the order of the transferred packets may be changed, so an appropriate protection time is provided in consideration of this, If the sequence number jumps within the protection time, it may be notified by NACK that there is a missing packet.

(Third embodiment)
FIG. 9 shows a third embodiment of the selective retransmission communication device of the present invention. The packet configuration of each part is as shown in FIG.

  The feature of this embodiment is missing by applying a forward error correction (FEC) algorithm (for example, pages 214 to 225 of Non-Patent Document 1) in the retransmission processing configuration and procedure of the first embodiment. The packet is being repaired.

  In FIG. 9, the transmitting apparatus 10C arranges an FEC packet generating unit 13 between the session layer packet assembling unit 12 and the transport layer packet assembling unit 14 in the transmitting apparatus 10A of the first embodiment, and the session layer packet An FEC packet is generated for the RTP packet output from the assembling unit 12. The RTP packet output from the session layer packet assembling unit 12 and the FEC packet output from the FEC packet generating unit 13 are input into the transport layer packet assembling unit 14, and are composed of a destination port number, a transmission source port number, and others. A UDP header is added to form a UDP packet. Other configurations and processing contents of each unit are the same as those in the first embodiment.

  The receiving device 20C arranges the error correction unit 25 between the transport layer packet termination unit 24 and the session layer packet termination unit 26 in the receiving device 20A of the first embodiment. The transport layer packet termination unit 24 removes the UDP header from the UDP packet and takes out the RTP packet and the FEC packet. When there is a missing RTP packet, the error correction unit 25 uses the FEC packet to repair the missing RTP packet. The RTP packet is input to the session layer packet termination unit 26, the RTP header is removed, and the compressed frame is reconstructed. Other configurations and processing contents of each unit are the same as those in the first embodiment.

  10 to 12 show an example of a packet retransmission procedure in the third embodiment. Here, it is assumed that one FEC packet is generated for eight RTP packets and that one missing packet can be repaired.

  In the transmitting device 10C, a plurality of packets to be transmitted are accumulated in the buffer of the data link layer packet assembling unit 16, and an importance table of these packets is created based on the importance identification signal output from the encoder 11. After the negotiation is established with the receiving device 20C, packets in the buffer (9 packets in FIGS. 10 to 12) are continuously transmitted, and then a block ACK request signal is transmitted.

  The data link layer packet termination unit 22 of the receiving device 20C returns a list of normally received packets as a block ACK to the transmitting device 10C. The data link layer packet assembling unit 16 of the transmitting apparatus 10C receives the block ACK and makes a retransmission process determination. That is, the importance level table is compared with the list in the block ACK, and the importance level of the packet that has not been normally received is confirmed. Or you may confirm the importance from the importance identification signal added to the header of the packet which was not received normally.

  Here, when all the packets are normally received, a transfer completion notification is transmitted to the receiving device 20C, and after the ACK is returned from the receiving device 20C, the packet in the buffer is deleted and the next packet transfer is performed. Start.

  Further, when one missing packet can be repaired by the FEC packet, and in the example illustrated in FIG. 10, when the missing packet 4 is repaired, the receiving device 20C performs block ACK in response to the block ACK request from the transmitting device 10C. The transmitting apparatus 10C confirms that all the packets have been received normally. Then, a transfer completion notification is transmitted to the receiving device 20C, and after the ACK is returned from the receiving device 20C, the packet in the buffer is deleted and the next packet transfer is started.

  In addition, when there are two missing packets that cannot be repaired by the FEC packet and the missing packet does not include a highly important packet, in the example shown in FIG. If both are low, retransmission processing is not performed and a transfer completion notification is transmitted to the receiving device 20A. After the ACK is returned from the receiving device 20A, the packet in the buffer is deleted and the next packet transfer is started. .

  In addition, in the example illustrated in FIG. 12, when there are two missing packets that cannot be repaired by the FEC packet and the missing packet includes a highly important packet, in the example illustrated in FIG. When the importance of the packet 4 is high, the packet 4 is retransmitted. The transmitting apparatus 10C transmits a packet 4, transmits a transfer completion notification after an ACK for the packet 4 is returned from the receiving apparatus 20C, and deletes the packet in the buffer after an ACK is returned from the receiving apparatus 20C. Start the next packet transfer. When the number of retransmissions reaches a predetermined number, a transfer completion notification is transmitted without performing the next retransmission, and after the ACK is returned from the receiving device 20C, the packet in the buffer is deleted and the next packet transfer is performed. To start.

(Fourth embodiment)
FIG. 13 shows a fourth embodiment of the selective retransmission communication device of the present invention. The packet configuration of each part is as shown in FIG.

  The feature of this embodiment is that a lost packet is repaired by applying an FEC algorithm (for example, pages 214 to 225 of Non-Patent Document 1) in the retransmission processing configuration and procedure of the second embodiment.

  In FIG. 13, the transmitting apparatus 10D arranges an FEC packet generating unit 13 between the session layer packet assembling unit 12 and the transport layer packet assembling unit 14 in the transmitting apparatus 10B of the second embodiment, and the session layer packet An FEC packet is generated for the RTP packet output from the assembling unit 12. The RTP packet output from the session layer packet assembling unit 12 and the FEC packet output from the FEC packet generating unit 13 are input into the transport layer packet assembling unit 14, and the destination port number, the source port number, and the encoder 11 An L4 header consisting of the importance level identification signal, sequence number, etc. is added to form an L4 packet. Other configurations and processing contents of each unit are the same as those in the second embodiment.

  The receiving device 20D arranges an error correction unit 25 between the transport layer packet termination unit 24 and the session layer packet termination unit 26 in the receiving device 20B of the second embodiment. The transport layer packet termination unit 24 removes the L4 header from the L4 packet and extracts the RTP packet and the FEC packet. When there is a missing RTP packet, the error correction unit 25 uses the FEC packet to repair the missing RTP packet. The RTP packet is input to the session layer packet termination unit 26, the RTP header is removed, and the compressed frame is reconstructed. Other configurations and processing contents of each unit are the same as those in the second embodiment.

  14 to 16 show examples of packet retransmission procedures in the fourth embodiment. Here, it is assumed that one FEC packet is generated for eight RTP packets and that one missing packet can be repaired.

  The transport layer packet assembly unit 14 of the transmission device 10D creates a packet importance table based on the importance identification signal output from the encoder 11, and the network layer packet assembly unit 15 converts the packet into an IP packet and transmits it.

  The transport layer packet termination unit 11 of the reception device 20D confirms the sequence number in the L4 header of the received L4 packet. If the sequence number is continuous, the transport layer packet termination unit 11 determines that it has been received normally and does not respond. On the other hand, if a jump occurs in the sequence number, it is determined that the packet is missing, and a NACK is returned to the transmitter 10D. The transport layer packet assembly unit 14 of the transmission device 10D receives NACK and makes a retransmission process determination. That is, the importance level of the lost packet notified by NACK is confirmed with reference to the importance level table. Or you may confirm the importance from the importance identification signal added to the header of the packet which was not received normally.

  Here, when all the packets have been normally received (when the sequence numbers are consecutive), the receiving device 20D does not send back a NACK, and therefore the transmitting device 10D does not perform a retransmission process.

  As shown in FIG. 14, when the packet 4 is lost and the packet 5 is received, the sequence number jumps, so the receiving device 20D returns a NACK to the transmitting device 10D. The transmitting apparatus 10D receives the NACK, but determines that it can be repaired by the FEC packet because there is no other missing packet, and does not perform the retransmission process.

  Also, as shown in FIG. 15, when packet 2 is lost and packet 3 is received, the sequence number jumps, so that receiving device 20D returns NACK to transmitting device 10D. Further, when the packet 5 is lost and the packet 6 is received, the sequence number jumps, so that the receiving device 20D returns a NACK to the transmitting device 10D. The transmitting apparatus 10D determines that the repair by the FEC packet is impossible by receiving two NACKs, and confirms the importance of the missing packets 2 and 5 notified by the NACK with reference to the importance table. Since the importance levels of these packets 2 and 5 are both low, retransmission processing is not performed.

  As shown in FIG. 16, when the packet 2 is lost and the packet 3 is received, the sequence number jumps, so the receiving device 20D returns a NACK to the transmitting device 10D. Further, when the packet 4 is lost and the packet 5 is received, the sequence number jumps, so that the receiving device 20D returns a NACK to the transmitting device 10D. The transmitting apparatus 10D determines that the repair by the FEC packet is impossible by receiving the two NACKs, and confirms the importance of the missing packets 2 and 4 notified by the NACK with reference to the importance table. Of these packets 2 and 4, packet 4 is of high importance, so that packet 4 is retransmitted.

  Here, it has been described that NACK is returned as soon as the sequence number jumps. However, in an actual network, the order of the transferred packets may be changed, so an appropriate protection time is provided in consideration of this, If the sequence number jumps within the protection time, it may be notified by NACK that there is a missing packet.

  Further, in the first embodiment and the third embodiment described above, a plurality of packets are transmitted continuously, and a packet received on the transmission side using a list of normally received packets notified by block ACK is used. It was the structure which recognizes. On the other hand, the block NACK request including the transmission list is made from the transmission side, the block NACK including the list of the missing packets is transmitted from the reception side, and the packet missing from the block NACK is recognized on the transmission side. Good.

  In the second and fourth embodiments described above, a NACK is transmitted when a packet loss is detected on the receiving side, and a retransmission process is determined by receiving the NACK on the transmitting side. there were. On the other hand, a configuration may be adopted in which ACK is transmitted when a packet is normally received on the receiving side, and retransmission processing is determined when ACK for the packet transmitted on the transmitting side is not received within a predetermined time.

  In the first to fourth embodiments described above, the importance level identification signal is added to the header of the packet to be transmitted on the transmission side. As a result, the importance level can be confirmed from the importance level identification signal added to the header of the packet that needs to be retransmitted, and it can be determined whether or not retransmission is necessary. Furthermore, for example, when there is a packet relay unit, the relay unit can recognize the importance level identification signal of each packet and use it for selective retransmission processing. On the other hand, if there is something like the importance table having a correspondence relationship between a packet to be transmitted on the transmission side and the importance identification signal, if selective retransmission processing according to the importance is possible, It is also possible to transmit without adding the importance level identification signal.

The figure which shows 1st Embodiment of the selective resending type | mold communication apparatus of this invention. The figure which shows the packet structure of each part of 1st Embodiment. The figure which shows the packet resending procedure in 1st Embodiment. The figure which shows the packet resending procedure in 1st Embodiment. The figure which shows 2nd Embodiment of the selective resending type | mold communication apparatus of this invention. The figure which shows the packet structure of each part of 2nd Embodiment. The figure which shows the packet resending procedure in 2nd Embodiment. The figure which shows the packet resending procedure in 2nd Embodiment. The figure which shows 3rd Embodiment of the selective resending type | mold communication apparatus of this invention. The figure which shows the packet resending procedure in 3rd Embodiment. The figure which shows the packet resending procedure in 3rd Embodiment. The figure which shows the packet resending procedure in 3rd Embodiment. The figure which shows 4th Embodiment of the selective resending type | mold communication apparatus of this invention. The figure which shows the packet resending procedure in 4th Embodiment. The figure which shows the packet resending procedure in 4th Embodiment. The figure which shows the packet resending procedure in 4th Embodiment.

Explanation of symbols

10A, 10B, 10C, 10D Transmitter 11 Encoder 12 Session layer packet assembly unit 13 FEC packet generation unit 14 Transport layer packet assembly unit 15 Network layer packet assembly unit 16 Data link layer packet assembly unit 17 Physical layer packet transmission unit 20A, 20B, 20C, 20D Receiver 21 Physical layer packet receiver 22 Data link layer packet termination unit 23 Network layer packet termination unit 24 Transport layer packet termination unit 25 Error correction unit 26 Session layer packet termination unit 27 Decoder 30 IP network

Claims (8)

Compressing and outputting the media data, and outputting the importance level identification signal indicating the importance level of the compressed data, and generating and transmitting a packet in which the importance level identification signal is added to the compressed data A transmission device comprising a packet transmission means for performing,
A packet terminating unit that receives a packet transmitted from the transmitting device and transmits a response signal indicating a packet that has not been normally received; and a restoring unit that restores the compressed data from the normally received packet. A receiving device with
The transmission device recognizes a packet that has not been normally received by a response signal transmitted from the reception device, and performs retransmission processing of a packet with high importance based on the importance identification signal added to the packet A selective retransmission type communication apparatus, characterized in that In the selective retransmission type communication device according to claim 1,
The selective retransmission type communication apparatus, wherein the packet transmission means is configured to add the importance level identification signal to a header of a packet of a data link layer. In the selective retransmission type communication device according to claim 1,
The selective retransmission type communication apparatus, wherein the packet transmission unit is configured to add the importance level identification signal to a header of a packet in a transport layer. Compressing means for compressing and outputting media data and outputting an importance level identifying signal indicating the importance level of the compressed data; and packet transmitting means for generating and transmitting a packet from the compressed data A transmitting device;
A packet terminating unit that receives a packet transmitted from the transmitting device and transmits a response signal indicating a packet that has not been normally received; and a restoring unit that restores the compressed data from the normally received packet. A receiving device with
The transmission device holds a correspondence relationship between the transmitted packet and the importance level identification signal, recognizes a packet that was not normally received by a response signal transmitted from the reception device, and sets the importance level of the packet to the correspondence A selective retransmission type communication device, characterized in that it is configured to perform retransmission processing of packets with high importance determined based on a relationship. Compressing and outputting the media data, and outputting the importance level identification signal indicating the importance level of the compressed data, and generating and transmitting a packet in which the importance level identification signal is added to the compressed data A transmission apparatus comprising: a packet transmission means for performing error correction packet transmission means for transmitting an error correction packet for repairing a packet that has not been normally received on the reception side;
Packet terminating means for receiving a packet transmitted from the transmitting device and transmitting a response signal indicating a packet that has not been normally received, and an error for repairing a packet that has not been normally received using the error correction packet A receiving device comprising a correcting means and a restoring means for restoring the compressed data from a normally received packet;
The transmitter recognizes a packet that has not been normally received by the response signal transmitted from the receiver, and determines that the packet cannot be repaired beyond the repair capability of the error correction packet; and A selective retransmission type communication apparatus, characterized in that it is configured to perform retransmission processing of a packet having high importance based on an importance identification signal added to the packet. In the selective retransmission type communication device according to claim 5,
The selective retransmission type communication apparatus, wherein the packet transmission means is configured to add the importance level identification signal to a header of a packet of a data link layer. In the selective retransmission type communication device according to claim 5,
The selective retransmission type communication apparatus, wherein the packet transmission unit is configured to add the importance level identification signal to a header of a packet in a transport layer. Compression means for compressing and outputting media data and outputting an importance level identifying signal indicating the importance level of the compressed data, a packet transmission means for generating and transmitting a packet from the compressed data, and a receiving side A transmission device comprising: an error correction packet transmission means for transmitting an error correction packet for repairing a packet that was not normally received in
Packet terminating means for receiving a packet transmitted from the transmitting device and transmitting a response signal indicating a packet that has not been normally received, and an error for repairing a packet that has not been normally received using the error correction packet A receiving device comprising a correcting means and a restoring means for restoring the compressed data from a normally received packet;
The transmission device holds a correspondence relationship between the transmitted packet and the importance level identification signal, recognizes a packet that is not normally received by a response signal transmitted from the reception device, and the error correction packet for the packet. The selective retransmission is characterized in that it is determined that repair cannot be performed beyond the repair capability of, and the importance level of the packet is determined based on the correspondence relationship, and retransmission processing of a highly important packet is performed. Type communication device.

Images