JP4939520B2 - Transmitting terminal, receiving terminal and transmission system used in one-way transmission path - Google Patents

Description

  The present invention relates to a transmission technique for compressing and transmitting IP header information by replacing IP header information with a context identifier (CID) in a one-way transmission path for packetizing and transmitting a file.

  2. Description of the Related Art Conventionally, in a transmission system that transmits and receives IP packets, a method is known in which a header of an IP packet is compressed when the IP packet is transmitted, and a compressed header packet to which a compressed header including only a part of the CID and the header is added. (See Non-Patent Document 1). In this system, instead of transmitting all packets with all headers, compressed header packets are transmitted to improve transmission efficiency in the transmission system. Here, the CID is information for specifying an IP data flow of a packet to be subjected to header compression.

  FIG. 13 is a diagram for explaining a header compression method using a full header packet, a compressed header packet, and a CID table. In this header compression method, a transmission terminal inputs an IP packet to be transmitted, specifies a CID based on an IP header and a UDP header added to the IP packet, and generates a CID table including the CID and header information. The transmitting terminal intermittently transmits a full header packet with a header including a CID, an IP header, and a UDP header, and transmits a compressed header packet with a compressed header including a CID at other times.

  When the receiving terminal receives the full header packet, the receiving terminal associates the CID included in the header of the full header packet with the IP header and the UDP header, and stores these data in the CID table. Then, the receiving terminal continues to receive the compressed header packet, searches the CID table based on the CID included in the header of the compressed header packet, acquires header information associated with the CID, and uses the CID as the original IP header. And restore to UDP header. Then, the receiving terminal generates and outputs an IP packet.

  FIG. 14 is a diagram showing the configuration of the CID table. (1) is a CID table when the IP header is IPv4, and (2) is a CID table when the IP header is IPv6. In (1), the IPv4 CID table includes a CID, an IPv4 header, and a UDP header. The IPv4 header includes a version (version) indicating the version of the IP header, an IHL (Internet Header Length), a TOS (Type Of Service: service type), an IP-ID (IP-Identification: IP identification number), and a flag. (Flag), Fragment Offset (fragment offset), TTL (Time To Live), Protocol (protocol), SrcAddr (source IP address), and DstAddr (destination IP address). The UDP header is composed of SrcPort (source port number) and DstPort (destination port number). In addition to the above, the IPv4 header has Total Length (packet length) and Header Checksum (header checksum), and the UDP header has Length (payload length) and Checksum (checksum) in addition to the above. Since these values are assumed to be different for each packet, they are not held in the CID table.

  In (2), the IPv6 CID table includes a CID, an IPv6 header, and a UDP header. The IPv6 header includes a version (version), a traffic class (traffic class), a flow label (flow label), a next header (next header), a hop limit (hop limit), and a srcAddr (source IP address) indicating the version of the IP header. And DstAddr (destination IP address). The UDP header is composed of SrcPort (source port number) and DstPort (destination port number). In addition to the above, the IPv6 header has a payload length (payload length), and the UDP header has a length (payload length) and a checksum (checksum) in addition to the above. Since they are assumed to be different, they are not held in the CID table.

  FIG. 15 is a diagram illustrating a configuration of a full header packet and a compressed header packet. (1) shows the configuration of an IPv4 full header packet, (2) shows the configuration of an IPv4 compressed header packet, (3) shows the configuration of an IPv6 full header packet, and (4) 3 shows the structure of an IPv6 compressed header packet. The numbers indicate the byte length of each data item (the same applies to FIGS. 16 to 18).

  In (1), an IPv4 full header packet includes a CID, an SN (sequence number) indicating the order of packets having the same CID, a CID_header_type (CID header type: 0x20) indicating a header information type, IPv4_header_wo_length, UDP_header_wo_length and data. Consists of bytes.

  In (2), the compressed header packet of IPv4 includes a CID, SN (sequence number) indicating the order of packets having the same CID, CID_header_type (CID header type: 0x21), and identification (identification) indicating the identification number of the IPv4 header. ID number) and data bytes.

  In (3), the IPv6 full header packet is composed of CID, SN (sequence number) indicating the order of packets having the same CID, CID_header_type (CID header type: 0x60), IPv6_header_wo_length, UDP_header_wo_length, and data bytes. The

  In (4), the IPv6 compressed header packet is composed of a CID, an SN (sequence number) indicating the order of packets having the same CID, a CID_header_type (CID header type: 0x61), and a data byte.

  (1) to (4) are distinguished by CID_header_type (CID header type) in the full header packet and the compressed header packet. Further, IPv4_header_wo_length and UDP_header_wo_length in the IPv4 full header packet according to (1) respectively correspond to the IPv4 header and the UDP header in the IPv4 CID table shown in FIG. Further, IPv6_header_wo_length and UDP_header_wo_length in the IPv6 full header packet according to (3) correspond to the IPv6 header and the UDP header in the IPv6 CID table shown in FIG. 14 (2), respectively.

  FIG. 16 is a diagram illustrating a configuration of IPv4_header_wo_length in the IPv4 full header packet illustrated in FIG. This IPv4_header_wo_length is a version (version) indicating the version of the IP packet, IHL, TOS (Type Of Service: service type), IP-ID (IP-Identification: IP identification number), Flag (flag), Fragment Offset (fragment offset) ), TTL (Time To Live), Protocol (protocol), SrcAddr (source IP address) and DstAddr (destination IP address).

  FIG. 17 is a diagram showing a configuration of IPv6_header_wo_length in the IPv6 full header packet shown in FIG. 15 (3). This IPv6_header_wo_length is a version (version) indicating the version of the IP packet, a traffic class (traffic class), a flow label (flow label), a next header (next header), a hop limit (hop limit), and a srcAddr (source IP address). And DstAddr (destination IP address).

  FIG. 18 is a diagram illustrating a configuration of UDP_header_wo_length in the IPv4 and 6 full header packets illustrated in FIGS. 15 (1) and 15 (3). This UDP_header_wo_length is composed of SrcPort (source port number) and DstPort (destination port number). Refer to Non-Patent Document 1 for details of the configuration shown in FIGS.

  In this way, in the header compression scheme shown in FIG. 13, the receiving terminal that receives the full header packet and the compressed header packet returns the full header prior to receiving the compressed header packet in order to restore the CID to the correct header information. It is necessary to receive the packet, associate the CID with the header information, and store a new CID record in the CID table. For this reason, the receiving terminal receives the compressed header packet received before the association between the CID and the header information because the correct CID record does not exist even if the CID table is referenced and the CID is unknown. It is necessary to discard the compressed header packet.

  When transmitting a file from the transmission terminal to the reception terminal, the transmission terminal generates attribute information of the file and transmits a packet of attribute information. Then, the transmitting terminal transmits the packet of the file body thereafter. The receiving terminal receives the attribute information packet and the file body packet transmitted by the transmitting terminal, and restores the file body to a file based on the attribute information.

  Therefore, prior to receiving the compressed header packet, the receiving terminal needs to associate the CID with the header information and store a new CID record in the CID table. Then, after the compressed header can be restored to the header information, the packet of the file body received thereafter can be restored to the file by receiving the attribute information packet.

  By the way, what uses FLUTE is known as a file transmission system using a unidirectional transmission path (see Non-Patent Document 2 and Patent Document 1). FLUTE is to transmit file attribute information and a file body as one object each time a file is packetized and transmitted. The attribute information of the file is described as FDT (File Delivery Table), and is handled as one object like the file body. That is, the transmitting terminal transmits the attribute information of the file as one object using the FLUTE packet, and subsequently transmits the file body as one object using the FLUTE packet.

  FIG. 19 is a diagram illustrating a configuration of a FLUTE packet. The FLUTE packet includes an IP header, a UDP header, a FLUTE header, and a FLUTE payload. The FLUTE header includes various information such as the length of the CCI field, CCI (Congestion Control Information) for identifying the congestion control method, TSI (Transport Session Identifier) for identifying the session in which the object is transmitted, A TOI (Transport Object Identifier) for identifying the current time, an SCT (Sender Current Time) indicating the current time of the transmitting terminal, and the remaining time that the object is transmitted in the time of the object transmitted by the FLUTE packet ERT (Expected Residual Time), Layer used to realize reliable transmission of content LCT header extension (EXT_FDT that transmits FDT instance identification information included in the payload of the packet, EXT_FTI that transmits information necessary to restore the object using the FEC, and the payload of the packet, which is an extension header in the red Coding Transport EXT_CENC indicating the encoding method), and identification information of the packet when the content file or FDT object is divided into FLUTE packet units, specifically, the number identifying the block and the packet order within the block It is composed of FEC Payload ID including information. Here, when the attribute information of the file is transmitted, the TOI of the FLUTE header is 0, and FDT (File Delivery Table) is stored in the FLUTE payload.

  In a file transmission system using such a one-way transmission path, in order to transmit a file from a transmission terminal to a reception terminal, the transmission terminal generates FDT that is attribute information of the file, and the FLUTE shown in FIG. Various data are set in the header, FDT is set in the FLUTE payload, and a packet of attribute information is transmitted. Further, the transmission terminal thereafter sets various data in the FLUTE header, sets the file body in the FLUTE payload, and transmits the packet of the file body. The receiving terminal receives the attribute information packet and the file body packet transmitted by the transmitting terminal, and restores the file body to a file based on the attribute information.

"Information and Communication Council, Information and Communication Technology Subcommittee (60th) Report of the 60-1-2 Broadcasting System Committee", [online], July 29, 2008, Information and Communication Council, [November 2008] Search on May 12], Internet <URL: http://www.soumu.go.jp/joho_tsusin/policyreports/joho_tsusin/bunkakai/080729_1.html> “FLUTE-File Delivery over Unidirectional Transport”, RFC 3926 US Patent Application Publication No. 2004/0153468

As described above, in the file transmission system using the one-way transmission path, the attribute information of the file is transmitted, and the file body is subsequently transmitted. On the other hand, according to the header compression scheme of the IP packet, regardless of the type of data stored in the IP packet, it is possible to compress the header. However, the timing of transmitting a packet capable of associating CID and header information (full header packet including CID and header information) from the transmission terminal is the attribute information that can restore the packet of the file body to the file. It may be later than the timing of transmitting a packet (a compressed header packet of attribute information including CID) . In this case, the receiving terminal (including CID, compressed header packet attribute information) packets received attribute information to, it is impossible to restore the compressed header based on the header information. For this reason, it is necessary to discard the attribute information packet. As a result, the attribute information cannot be acquired. To acquire the attribute information, it is necessary to wait until the attribute information packet is received again.

  Accordingly, the present invention has been made to solve the above-described problems, and an object of the present invention is to transmit file attribute information at a receiving terminal when a file is packetized and transmitted via a one-way transmission path. An object of the present invention is to provide a transmission terminal, a reception terminal, and a transmission system that can reliably acquire file attribute information without discarding a packet.

In order to solve the above problem, the transmitting terminal according to the present invention transmits the attribute information of a file and header information for the IP data flow when transmitting a plurality of units into which the file body is divided as the same IP data flow. A CID table composed of a CID record including the CID and header information at a transmitting terminal that transmits a compressed header packet including the CID by compressing the header by replacing it with a context identifier (CID) for specifying an IP data flow; CID is determined based on header information for the IP data flow, a CID record including the CID and header information is generated and stored in the CID table, and a full header packet of attribute information including the CID and header information is generated. And from the CID table Reads the ID, the full header packet compressed header packet generating unit for generating a compressed header packet attribute information including the compressed header packet and the CID of the unit including the CID, generated by the full header packet compressed header packet generating unit The attribute information full header packet and the unit compressed header packet are transmitted in this order, and then the attribute information compressed header packet and the unit compressed header packet are transmitted in this order, and the attribute information full header is transmitted. And a transmission control unit that repeats transmission of the packet and unit compressed header packet and transmission of the attribute information compressed header packet and unit compressed header packet .

In addition, the transmission terminal according to the present invention specifies the IP data flow, the header information for the IP data flow, when transmitting the attribute information of the file and a plurality of units into which the file body is divided as the same IP data flow. A CID table composed of a CID record including the CID and header information, and the IP data flow in a transmitting terminal that transmits the compressed header packet including the CID by compressing the header with a context identifier (CID) for CID is determined based on the header information for, generating a CID record including the CID and header information, storing the CID record in the CID table, reading the CID from the CID table, a compressed header packet of the unit including the CID, and Attribute information including the CID A compressed header packet generator for generating a compressed header packet, and a control packet for generating a CID record update packet for writing a CID record including the CID and header information in a CID table provided on the side receiving the compressed header packet The CID record update packet generated by the generation unit and the control packet generation unit is transmitted, and then the compressed header packet of the attribute information and the compressed header packet of the unit generated by the compressed header packet generation unit in this order. And a transmission control unit that repeats transmission of the CID record update packet and transmission of the compressed header packet of the attribute information and the compressed header packet of the unit .

Also, the receiving terminal according to the present invention is configured such that the header information for the IP data flow is the IP data under the transmission system in which the attribute information of the file and the plurality of units into which the file body is divided are transmitted as the same IP data flow. A CID composed of a CID record including the CID and header information at a receiving terminal that receives a compressed header packet that is replaced with a context identifier (CID) for specifying a flow and is header-compressed and transmitted. A table, a header including attribute information including the CID and header information, and a compressed header packet of the unit including the CID in this order, and then a unit including the compressed header packet and the CID of the attribute information including the CID. The compressed header packet in this order Received, the reception of the compressed header packet full header packet and the unit of the attribute information, the attribute information compressed header packet and repeating the reception of the compressed header packet units, and distinguishes reception control unit the received packet, For the full header packet of the attribute information distinguished by the reception control unit, a CID record including the CID and header information in the full header packet of the attribute information is written to the CID table, and the IP data from the full header packet of the attribute information Header information from the CID table using the CID in the compressed header packet of the unit for the full header packet processing unit that generates a packet of attribute information constituting the flow and the compressed header packet of the unit distinguished by the reception control unit Read And generating a packet of a unit constituting the IP data flow, and reading out the header information from the CID table using the CID in the compressed header packet of the attribute information for the compressed header packet of the attribute information, And a compressed header packet processing unit that generates a packet of attribute information constituting the flow.

Also, the receiving terminal according to the present invention is configured such that the header information for the IP data flow is the IP data under the transmission system in which the attribute information of the file and the plurality of units into which the file body is divided are transmitted as the same IP data flow. A CID composed of a CID record including the CID and header information at a receiving terminal that receives a compressed header packet that is replaced with a context identifier (CID) for specifying a flow and is header-compressed and transmitted. CID record update packet including the table and the CID and header information is received, and then the compressed header packet of the attribute information including the CID and the compressed header packet of the unit including the CID are received in this order, and the CID record Receive update packets and Repeating the reception of the compressed header packet of compressed header packet and the unit of information, and distinguishes the reception control unit the received packet, the differentiated CID record update packets by the receiving control unit, CID in the CID record update packets and The control packet processing unit that writes the CID record including the header information to the CID table, and the compressed header packet of the attribute information distinguished by the reception control unit, the CID table using the CID in the compressed header packet of the attribute information Header information is read out from the CID table, and a packet of attribute information that constitutes the IP data flow is generated. Reads header information, characterized by comprising a compression header packet processor for generating a packet of units constituting the IP data flow.

  The transmission system according to the present invention is characterized by comprising the transmitting terminal and the receiving terminal.

  As described above, according to the present invention, it is not necessary to discard a packet for transmitting file attribute information at the receiving terminal, and the file attribute information can be reliably acquired.

The best mode for carrying out the present invention will be described below in detail with reference to the drawings.
[Transmission system]
FIG. 1 is a diagram illustrating a schematic configuration of a transmission system in which a transmission terminal and a reception terminal according to an embodiment of the present invention are used. This transmission system is a system that realizes a content file download service by, for example, advanced BS digital broadcasting, and includes a transmission terminal 1 and a reception terminal 2. The transmission terminal 1 and the reception terminal 2 are connected by a one-way transmission path 3 through which a packet is transmitted from the transmission terminal 1 to the reception terminal 2.

  The transmission terminal 1 is an apparatus that stores file attribute information and a file body in an IP packet, compresses header information of the IP packet to generate a compressed header, and transmits the compressed header to the reception terminal 2 via the one-way transmission path 3. is there. The receiving terminal 2 receives the packet transmitted from the transmitting terminal 1 via the one-way transmission path 3, returns the compressed header of the packet in which the header information is compressed, to the original header information, and sets the file attribute information and the file It is a device that acquires the main body and restores it to the original file. The one-way transmission path 3 is a broadcast transmission path, for example.

[Sending terminal]
Next, the transmission terminal 1 shown in FIG. 1 will be described. FIG. 2 is a block diagram illustrating a configuration of the transmission terminal 1. The transmission terminal 1 includes a storage unit 11, an attribute information generation unit 12, a unit generation unit 13, a download header addition unit 14, an IP packet generation unit 15, a full header packet / compressed header packet generation unit 16, a control packet generation unit 17, A transmission control unit 18 and a CID table 10 are provided. The CID table 10 is stored in a memory such as a RAM, and has the same configuration as the CID table shown in FIG.

  The storage unit 11 stores content and metadata files transmitted to the receiving terminal 2 using the unidirectional transmission path 3.

(Generation of attribute information)
The attribute information generation unit 12 reads a file from the storage unit 11 and generates attribute information including the name of the file body and the length of the file. If the size of the generated attribute information is larger than the data unit size (preset) described later, the generated attribute information is divided into the data unit sizes.

  FIG. 3 is a diagram illustrating a configuration of attribute information. As shown in FIG. 3, the attribute information specifies “number of bits in the Block Number (block number BN) field in the download header”, “number of packets in the block”, “last sequence number of the attribute information packet”, and “FEC method”. “URI (file body name)” “File Length (file length)” “Content Type (content type)” “Final block number and final sequence number of the final block” “Storage destination” Directory structure ”“ Content Encoding (content encoding) ”“ Transfer Length (transmission length) ”“ Content MD5 (content MD5) ”.

The attribute information generation unit 12 sets each component shown in FIG. 3 based on the read file, and generates attribute information. Specifically, the attribute information generation unit 12 sets a bit length preset according to the type and characteristics of the one-way transmission path 3 to “the number of bits of the block number BN field in the download header”. Details of the download header and the block number BN will be described later.

  The attribute information generation unit 12 sets the preset number of packets in the block to “number of packets in block”. The “number of packets in a block” is the number of packets transmitted in the block in a block that is an aggregate of data units divided from the file body and parity units generated from the data units.

  When the attribute information generation unit 12 divides the generated attribute information, the attribute information generation unit 12 sets the number of divided attribute information to “the last sequence number of the attribute information packet”. If the size of the attribute information is equal to or smaller than the size of the data unit, the “last sequence number of the attribute information packet” is 0.

  The attribute information generation unit 12 sets the file size to “File Length (file length)” and the content type to “Content Type (content type)”. Then, the attribute information generation unit 12 calculates the number of blocks and the number of sequences based on the number of data units and parity units generated by the unit generation unit 13 described later, the size of the data unit set in advance, and the like. These are set to “the last block number for transmitting the file and the last sequence number of the last block”.

  When encoding and transmitting a file, the attribute information generating unit 12 sets the method to “Content Encoding (content encoding)” and sets the length of the file at the time of transmission to “Transfer Length (transmission length)”. . The reason why “Transfer Length (transmission length)” is set is that when the file is encoded and transmitted, the length of the original file is different from the length of the file at the time of transmission. In addition, a checksum for checking whether or not the receiving side has received the file correctly is set to “Content MD5 (content MD5)”. Further, when generating a parity unit, which will be described later, the type of the generation method is set to “identifier for specifying the FEC method”, and “URI (name of file body)” and “directory configuration of storage destination” are also set. .

(Unit generation)
Returning to FIG. 2, the unit generation unit 13 reads the file from the storage unit 11 (reads the same file as the file read by the attribute information generation unit 12), and stores the file body in a preset data unit of a certain size. To divide. Here, the size of the data unit can be freely set. For example, it is 1344 bytes or 4032 bytes.

  The unit generation unit 13 divides the data unit divided into a plurality of L × D pieces and arranges them in two dimensions of L columns and D rows. This collection of two-dimensional data units is the source of the block. Then, the unit generation unit 13 generates a parity unit from each data unit in the column direction and the row direction in the aligned two-dimensional data units. For example, mod 2 is added to all data units for each column direction to generate a parity unit for each column direction. Similarly, mod2 is added to all data units in the row direction to generate parity units in the row direction.

  Further, the unit generation unit 13 generates a block using the aligned two-dimensional data unit aggregate and the generated parity units in the column direction and the row direction.

(Add download header)
The download header adding unit 14 adds a download header to the attribute information generated by the attribute information generating unit 12, and also adds a download header to the data unit and the parity unit generated by the unit generating unit 13. To do.

  FIG. 4 is a diagram showing the configuration of the download header. As shown in FIG. 4, the download header is a 64-bit header composed of three fields, “Transport File ID (Transport File ID: TFID)”, “Block Number (block number BN)”, “Sequence Number” (sequence) Number SN) ". The number of bits (field width) of the “TFID” field is 32. The total number of bits in the “block number BN” and “sequence number SN” fields is 32, but each has a variable length, depending on the type and characteristics of the one-way transmission path 3 or the file to be transmitted. It is set in advance. Further, during transmission of one file, these field widths are not changed and fixed values are used.

  “TFID” serves as a label for uniquely identifying a file to be transmitted, and the same numerical value is assigned to the same file transmission. Therefore, the download header adding unit 14 sets the same “TFID” for the attribute information, data unit, and parity unit of the same file. On the other hand, different “TFID” is set for attribute information of different files. The receiving terminal 2 can identify the file by “TFID”. In the FLUTE header of the FLUTE packet shown in FIG. 19, this “TFID” corresponds to “TOI (Transport Object Identifier)”.

  “Block number BN” indicates the block number in the file to be transmitted. “Sequence number SN” indicates the number of attribute information (each attribute information when divided) and the number of a unit in a block (hereinafter, a data unit and a parity unit are collectively referred to as a unit). For example, BN = 0 and SN = 0 are set for the first attribute information, and an SN subsequent to the SN set for the last attribute information is set for the unit following the attribute information.

  More specifically, when one attribute information is generated by the attribute information generating unit 12, the download header adding unit 14 determines that BN = 0 and SN = 0 for the attribute information in the first block (BN = 0). Set. Then, the download header adding unit 14 sets BN = 0 and SN = 1 for the head unit of the first block, and sets BN = 0 and SN = 2 for the next unit. The sequence number SN increases by 1 according to the number of units. The download header adding unit 14 also sets BN = 0 and SN = 0 for the same attribute information as the attribute information in the first block in the next block (BN = 1). The download header adding unit 14 sets BN = 1 and SN = 1 for the head unit of the block (BN = 1), and sets BN = 1 and SN = 2 for the next unit.

  On the other hand, when the attribute information generated by the attribute information generation unit 12 is divided into a plurality of pieces, the download header addition unit 14 adds BN = 0 to the first divided attribute information in the first block (BN = 0). , SN = 0, and BN = 0, SN = 1 for the next attribute information. The sequence number SN increases by 1 in accordance with the division of the attribute information. Then, the download header adding unit 14 sets BN = 0 and SN = 2 for the head unit of the first block (BN = 0), and sets BN = 0 and SN = 3 for the next unit. . The sequence number SN increases by 1 according to the number of units. Here, when the number of attribute information generated and divided by the attribute information generation unit 12 is n, the sequence number SN of each attribute information is SN = 0, 1,..., N−1. The sequence number SN of the first unit is SN = n. The download header adding unit 14 also sets BN = 0, SN = 0, 1,... Of the same attribute information as the attribute information in the first block in the next block (BN = 1). Then, the download header adding unit 14 sets BN = 1, SN = 2 (when the number of divided attribute information is two) for the head unit of the block (BN = 1), and the next BN = 1 and SN = 3 are set for the unit. As described above, the sequence number SN increases by 1 according to the number of units, and when the final attribute information is SN = n−1, the first unit is SN = n.

  As described above, the download header adding unit 14 adds a download header including the TFID, the block number BN, and the sequence number SN to the attribute information and the unit. In this case, the download header addition unit 14 assigns the same attribute information to a plurality of blocks generated by the unit generation unit 13, and BN is assigned to the first attribute information among the attribute information corresponding to one block. = 0 and SN = 0 are unified and set. Thereby, the receiving terminal 2 determines whether or not the 32-bit data obtained by concatenating both the block number BN and the sequence number SN fields in the download header is 0x00000000 for the received packet. If it is determined that the packet number is 0x00000000, a packet having such a download header includes a packet containing the attribute information of the file (initially) regardless of the setting of the bit number of the block number BN field and the bit number of the sequence number SN field. Can be recognized.

(IP packet generation)
Returning to FIG. 2, the IP packet generation unit 15 adds an IP header and a UDP header to the attribute information and unit to which the download header is added by the download header addition unit 14, and generates and outputs an IP packet.

  FIG. 5 is a diagram illustrating a configuration of an IP packet output from the IP packet generation unit 15. As shown in FIG. 5, the IP packet output from the IP packet generator 15 includes an IP header, a UDP header, a download header, and unit or attribute information. Here, the IP header includes a protocol type, a source IP address, and a destination IP address, and the UDP header includes a source port number and a destination port number. Identified. An IP data flow is an IP packet having a unique combination of the values of five fields of protocol type, source IP address, destination IP address, source port number, and destination port number included in the IP header and UDP header. A set. That is, the IP data flow specified by the data included in the IP header and the UDP header is a set of IP packets in the same file read and transmitted by the storage unit 11.

(Generation of full header packet, compressed header packet, control packet)
Returning to FIG. 2, the full header packet / compressed header packet generation unit 16 inputs the IP packet from the IP packet generation unit 15, and inputs the plurality of input IP packets into the IP header described in the header of the IP packet, and A distinction is made based on the UDP header to identify the IP data flow.

  The full header packet / compressed header packet generation unit 16 determines a CID that can be assigned for each identified IP data flow, and generates a CID record including various data of the CID, IP header, and UDP header, as shown in FIG. Save in the CID table 10. The full header packet / compressed header packet generator 16 reads various data from the CID table 10, generates the full header packet and the compressed header packet shown in FIGS. 15 to 18, and outputs them to the transmission controller 18. Specifically, the full header packet / compressed header packet generation unit 16 sets the CID for each identified IP data flow, sets the order of packets having the same CID to SN, and the IPv4 read from the CID table 10. When the version (version) of 6 is 4, 0x20 is set to CID_header_type, and when it is 6, IPv4, 6 header and UDP header read from the CID table 10 are set to IPv4, 6_header_wo_length and UDP_header_wo_length, respectively. A full header packet is generated by setting attribute information or a unit in a data byte. Similarly, CID, SN, and CID_header_type are set. In the case of IPv4, an identification (identification number) is set, and attribute information or a unit is set in a data byte to generate a compressed header packet. In the third embodiment to be described later, only a compressed header packet is generated without generating a full header packet.

  The control packet generation unit 17 reads the CID record from the CID table 10, generates a CID record update packet when a new CID record exists, and generates a CID record deletion packet when the CID record is deleted. Are output to the transmission control unit 18. In the first embodiment, which will be described later, no control packet is generated. In the second embodiment, only a CID record deletion packet is generated. In the third embodiment, a CID record update packet and a CID record deletion packet are generated.

  FIG. 6 is a diagram illustrating a configuration of a CID record update packet. As shown in (1), the IPv4 CID record update packet is composed of CID, SN, CID_header_type (CID header type: 0x2F), IPv4_header_wo_length, and UDP_header_wo_length. Also, as shown in (2), the IPv6 CID record update packet is composed of CID, SN, CID_header_type (CID header type: 0x6F), IPv6_header_wo_length, and UDP_header_wo_length. When the receiving terminal 2 receives the CID record update packet, the CID, IPv4, 6_header_wo_length, and UDP_header_wo_length of the CID record update packet are stored in the CID table as a CID record including a CID, an IP header, and a UDP header. This CID record update packet has the same configuration as the full header of the IPv4 full header packet shown in FIG. 15 (1) and the full header of the IPv6 full header packet shown in FIG. 15 (3). Yes. That is, the CID record update packet is equivalent to a configuration in which the data byte area is removed from these full header packets.

  FIG. 7 is a diagram illustrating a configuration of a CID record deletion packet. As shown in FIG. 7, the CID record deletion packet is composed of CID, SN, and CID_header_type (CID header type: 0x80). When receiving the CID record deletion packet, the receiving terminal 2 deletes the CID record indicated by the CID of the CID record deletion packet from the CID table.

  FIG. 8 is a diagram illustrating a configuration of a CID record deletion packet for deleting a plurality of CID records. As shown in FIG. 8, the CID record deletion packet is composed of CID, SN, CID_header_type (CID header type: 0x80), and CID. When receiving the CID record deletion packet, the receiving terminal 2 deletes the CID records indicated by the plurality of CIDs in the CID record deletion packet from the CID table.

  Specifically, when generating the CID record update packet, the control packet generation unit 17 uses the CID, IP header, and UDP header of the new CID record read from the CID table 10 as the CID of the CID record update packet, IPv4, 6_header_wo_length. And UDP_header_wo_length, set SN (sequence number) indicating the order of packets having the same CID, and set CID_header_type (CID header type: 0x2F or 0x6F) according to the protocol type of the IP data flow . Further, the control packet generator 17 deletes the CID of the deleted CID record from the CID records stored when the CID record is read from the CID table 10 when generating the CID record deletion packet. Set to the CID of the packet, set SN (sequence number) indicating the order of packets having the same CID, and further set CID_header_type (CID header type: 0x80).

Table 1 shows allocation of CID_header_type (CID header type) in a full header packet, a compressed header packet, a CID record update packet, and a CID record deletion packet. The CID header type has different values depending on IPv4 and IPv6 except for the CID record deletion packet.

  Returning to FIG. 2, the transmission control unit 18 inputs the full header packet and the compressed header packet generated by the full header packet / compressed header packet generation unit 16, and at the same time receives the control packet ( CID record update packet and CID record deletion packet). Then, the transmission control unit 18 transmits each packet to the one-way transmission path 3 in accordance with a preset transmission order. Here, the packet is stored in the TLV and transmitted. The TLV includes a future reservation, a TLV packet type, a data length, and data fields, and actual information such as a packet and an AMT is stored in the data field. Refer to Non-Patent Document 1 for details of TLV.

[Receiving terminal]
Next, the receiving terminal 2 shown in FIG. 1 will be described. FIG. 9 is a block diagram illustrating a configuration of the receiving terminal 2. The receiving terminal 2 includes a reception control unit 21, a control packet processing unit 22, a full header packet processing unit 23, a compressed header packet processing unit 24, a CID table 20, a download header analysis unit 25, a file restoration unit 26, and a storage unit 27. I have. The CID table 20 is stored in a memory such as a RAM and has the same configuration as the CID table shown in FIG.

  The reception control unit 21 receives a packet from the one-way transmission path 3 and distinguishes it into a full header packet, a compressed header packet, and a control packet based on CID_header_type (CID header type). The reception control unit 21 outputs the full header packet to the full header packet processing unit 23, the compressed header packet to the compressed header packet processing unit 24, and the control packet to the control packet processing unit 22. Here, since the reception control unit 21 receives the TLV storing the packet, the reception control unit 21 performs processing for recognizing and extracting the packet from the TLV.

(Full header packet and compressed header packet processing)
The full header packet processing unit 23 receives a full header packet from the reception control unit 21, extracts a CID, IPv4, 6_header_wo_length, and UDP_header_wo_length from the full header packet, generates a CID record including a CID, an IP header, and a UDP header. Save in table 20. Then, the full header packet processing unit 23 removes the CID, SN, and CID_header_type (CID header type) from the full header packet, adds the length calculated from the “data length” field of the TLV, and further calculates the checksum. The IP packet is generated and output.

  The compressed header packet processing unit 24 inputs the compressed header packet from the reception control unit 21, extracts the CID that is the compressed header from the compressed header packet, searches the CID table 20 using the CID as a key, and searches for CID records having the same CID. Read IP header and UDP header. Then, the compressed header packet processing unit 24 removes the CID, SN, and CID_header_type (CID header type) from the compressed header packet, adds the read IP header and UDP header, and calculates from the “data length” field of the TLV. A length is added, and a checksum is calculated and added to generate and output an IP packet. The full header packet processing unit 23 and the compressed header packet processing unit 24 output IP packets in the order according to the SNs of the full header packet and the compressed header packet. The configuration of the IP packet output here is the same as that shown in FIG.

(Control packet processing)
The control packet processing unit 22 receives a control packet from the reception control unit 21 and discriminates between a CID record update packet and a CID record deletion packet based on CID_header_type (CID header type) shown in Table 1.

  When the input packet is a CID record update packet, the control packet processing unit 22 extracts the CID, IPv4, 6_header_wo_length, and UDP_header_wo_length from the CID record update packet, generates a CID record including the CID, IP header, and UDP header, and generates a CID table. Save to 20. When the input packet is a CID record deletion packet, the control packet processing unit 22 extracts the CID from the CID record deletion packet and deletes the CID record indicated by the CID from the CID table 20. When there are a plurality of CIDs, the plurality of CID records are deleted from the CID table 20.

(Download header analysis)
The download header analysis unit 25 receives an IP packet from the full header packet processing unit 23 and the compressed header packet processing unit 24, and acquires file attribute information and a unit based on the download header included in the IP packet. Specifically, the download header analysis unit 25 refers to a 64-bit download header included in the IP packet, and identifies a file based on a 32-bit “TFID” constituting the download header. As described above, since the same numerical value is assigned to “TFID” for the same file transmission, the file can be identified.

  The download header analysis unit 25 determines whether or not the attribute information of the identified file has been acquired. If the download header analysis unit 25 determines that the attribute information has not been acquired, the IP input from the full header packet processing unit 23 and the compressed header packet processing unit 24 For the packet, it is determined whether the block number BN and sequence number SN of the download header are BN = 0 and SN = 0, and waits until data of BN = 0 and SN = 0 is input. When it is determined that the download header is BN = 0 and SN = 0, the IP packet is recognized as including the first attribute information, and the first attribute information “block number BN field in download header” is recognized. By referring to the “number of bits”, the block number BN and sequence number SN fields, which are the next 32 bits of “TFID” in the download header, are recognized. Then, for the IP packet input thereafter, the block number BN and the sequence number SN when the “TFID” in the download header is the same are specified. Then, the download header analysis unit 25 refers to the “last sequence number of the attribute information packet” of the first attribute information, and the sequence number SN of the IP packet input thereafter is the same as the “final sequence number of the attribute information packet”. Until then, the IP packet is acquired as attribute information in the same file.

  The download header analysis unit 25 refers to the “number of packets in the block” of the attribute information so that the last unit in the block can be identified, and the “last block number for transmitting the file and the final sequence number of the last block” The final block can be specified, and the unit of the final block and the unit of the final sequence in the final block can be specified. Then, the download header analysis unit 25 acquires all the units of all the blocks in the same file for the IP packet input after acquiring all the attribute information. Then, the acquired attribute information and all units are output to the file restoration unit 26.

(File restoration)
The file restoration unit 26 inputs the attribute information and all units in the same file from the download header analysis unit 25, and sets the data unit and parity unit in the block number order and in the block by the block number BN and sequence number SN of the download header. Are arranged in the order of their sequence numbers. Then, the file restoration unit 26 refers to the “identifier for specifying the FEC method” in the attribute information, performs FEC decoding processing using the parity unit, restores the missing data unit, and combines the data units. To do. Then, the file restoration unit 26 restores the original file and writes it in the storage unit 27.

Next, a specific embodiment using the transmitting terminal 1 shown in FIG. 2 and the receiving terminal 2 shown in FIG. 9 will be described.
[Example 1]
First, Example 1 will be described. In the first embodiment, when transmitting the same file, the transmitting terminal 1 transmits attribute information necessary for restoring the file in the receiving terminal 2 as a full header packet.

  FIG. 10 is a diagram illustrating the transmission order of each packet according to the first embodiment. As shown in FIG. 10, when transmitting the same file, the full header packet of the attribute information and the compressed header packet of the unit are transmitted for each block, and after the compressed header packet of the unit in the final block is transmitted, the CID record is deleted. A packet is sent.

  This will be specifically described below. First, the process of the transmission terminal 1 will be described. The attribute information generation unit 12 and the unit generation unit 13 of the transmission terminal 1 read the file 1 from the storage unit 11 and generate attribute information and a unit, respectively. The download header adding unit 14 adds a download header to the attribute information and unit generated by the attribute information generating unit 12 and the unit generating unit 13. Since the detailed processing of the attribute information generation unit 12, the unit generation unit 13, and the download header addition unit 14 has been described above, a description thereof will be omitted.

  The IP packet generation unit 15 receives the attribute information and unit to which the download header is added, generates an IP packet by adding the IP header and the UDP header, and outputs the IP packet in the order shown in FIG. . That is, the IP packet generation unit 15 includes an IP packet of attribute information (BN = 0, SN = 0), an IP packet of a plurality of units in block 0 (BN = 0, SN = 1, 2,...), Attribute IP packet of information (BN = 0, SN = 0), IP packet of a plurality of units in block 1 (BN = 1, SN = 1, 2,...),..., IP packet of attribute information (BN = 0, SN = 0), and IP packets of a plurality of units in the final block n (BN = n, SN = 1, 2,...) Are output in this order.

  When the full packet packet / compressed header packet generation unit 16 receives the IP packet of the file 1 from the IP packet generation unit 15, the IP data flow is specified to determine the CID, and the CID record including the CID, IP header, and UDP header Is newly generated and stored in the CID table 10. Further, when an IP packet of attribute information is input, the full header packet / compressed header packet generator 16 generates the full header packet shown in FIGS. On the other hand, when the unit IP packet is input, the compressed header packet shown in FIGS. 15 (2) and 15 (4) is generated. When the attribute information is divided into a plurality of pieces by the attribute information generation unit 12, a full header packet is generated only for the top attribute information, and a compressed header packet is generated for the other attribute information. The same applies to the attribute information for each block. Further, the full header packet / compressed header packet generation unit 16 deletes the generated CID record from the CID table 10 when the generation of all the full header packets and the compressed header packet is completed. The specific method for generating the full header packet and the compressed header packet by the full header packet / compressed header packet generation unit 16 has already been described, and is omitted here.

  The control packet generator 17 reads and stores the CID record newly stored by the full header packet / compressed header packet generator 16 from the CID table 10 and recognizes that the CID record has been deleted from the CID table 10. At this time, as shown in FIGS. 7 and 8, a CID record deletion packet including the CID of the stored CID record is generated.

  The transmission control unit 18 inputs the full header packet of the attribute information generated by the full header packet / compressed header packet generation unit 16 and the compressed header packet of the unit, and the CID record deletion packet generated by the control packet generation unit 17 Enter. Then, as shown in FIG. 10, the transmission control unit 18 transmits the full header packet of the attribute information and the compressed header packet of a plurality of units in this order for each block, and the compressed header packet of the plurality of units in the final block. Is transmitted, and then a CID record deletion packet is transmitted. As described above, when the attribute information is divided into a plurality of pieces by the attribute information generation unit 12, the full header packet is transmitted only for the top attribute information, and the compressed header packet is transmitted for the other attribute information. This is the same for all blocks.

  When the file 2 is subsequently transmitted, the same processing as that for transmitting the file 1 is performed.

  Next, processing of the receiving terminal 2 will be described. When the reception control unit 21 of the reception terminal 2 receives the packet of the file 1 transmitted from the transmission terminal 1, the reception header 21 receives a full header packet (full header packet of attribute information), a compressed header packet based on the CID_header_type (CID header type). (Unit compressed header packet, if attribute information is divided, compressed header packet of attribute information other than the head) and CID record deletion packet.

  The full header packet processing unit 23 receives the full header packet of the attribute information from the reception control unit 21, extracts the CID, IPv4, 6_header_wo_length, and UDP_header_wo_length from the full header packet, and obtains the CID record including the CID, IP header, and UDP header. Generate and save in the CID table 20. Then, the full header packet processing unit 23 removes the CID, SN, and CID_header_type (CID header type) from the full header packet of the attribute information, adds the length calculated from the “data length” field of the TLV, and A checksum is calculated and added, and an IP packet of attribute information is generated and output. As a result, the full header packet processing unit 23 receives the full header packet of the attribute information, generates a new CID record, stores it in the CID table 20, and converts the compressed header to the original header for the subsequent compressed header packet. Information can be restored correctly. Further, since the IP packet of attribute information can be generated from the full header packet of attribute information, it is not necessary to discard the input attribute information.

  The compressed header packet processing unit 24 inputs the compressed header packet of the unit and the compressed header packet of the attribute information other than the head from the reception control unit 21, extracts the CID that is the compressed header from the compressed header packet, and uses the CID as a key for the CID The table 20 is searched, and the IP header and UDP header of the CID record having the same CID are read out. Then, the compressed header packet processing unit 24 removes the CID, SN, and CID_header_type (CID header type) from the compressed header packet, adds the read IP header and UDP header, and calculates from the “data length” field of the TLV. A length is added, and a checksum is calculated and added to generate and output an IP packet. The full header packet processing unit 23 and the compressed header packet processing unit 24 output IP packets in the order according to the SNs of the full header packet and the compressed header packet.

  The control packet processing unit 22 inputs the CID record deletion packet distinguished by the reception control unit 21 and deletes the CID record indicated by the CID from the CID table 20.

  The download header analysis unit 25 receives the IP packet from the full header packet processing unit 23 and the compressed header packet processing unit 24, identifies the file based on the “TFID” of the download header, and as described above, the attribute information of the file 1 And get the file body.

  The file restoration unit 26 inputs the attribute information and all the units in the file 1 from the download header analysis unit 25, and based on the block number BN and the sequence number SN of the download header, the data unit and the parity unit are sorted in the block number order and Arrange in order of sequence number in block. Then, FEC decoding processing using the parity unit is performed, the missing data unit is restored, and the data units are combined. Then, the file restoration unit 26 restores the original file 1 and writes it in the storage unit 27.

  As described above, according to the first embodiment, the transmission terminal 1 transmits the attribute information necessary for restoring the file in the reception terminal 2 as a full header packet when transmitting the same file. That is, the transmitting terminal 1 transmits a full header packet of attribute information and a compressed header packet of a plurality of units in this order for each block, and after transmitting a compressed header packet of a plurality of units in the final block, the CID record deletion packet Send. The receiving terminal 2 receives the full header packet of the attribute information, generates a new CID record, stores it in the CID table 20, and generates an IP packet from the full header packet of the attribute information to acquire the attribute information. . Then, the file body is acquired from the compressed header packet of the unit received thereafter. As a result, when the receiving terminal 2 receives a packet of attribute information necessary for restoring the file, it is not necessary to discard the attribute information packet, and the attribute information of the file can be reliably acquired. Become.

[Example 2]
Next, Example 2 will be described. In the second embodiment, when transmitting the same file, the transmitting terminal 1 transmits the attribute information necessary for restoring the file in the receiving terminal 2 as a full header packet, and thereafter, the same attribute information is compressed header packet. To send as. For example, the transmission terminal 1 transmits a full header packet of attribute information as the first packet in file transmission, and then alternately transmits a compressed header packet of attribute information and a full header packet of attribute information for each block. .

  FIG. 11 is a diagram illustrating the transmission order of each packet according to the second embodiment. As shown in FIG. 11, when transmitting the same file, a full header packet of attribute information and a compressed header packet of unit, and a compressed header packet of attribute information and a compressed header packet of unit are alternately transmitted for each block, After the compressed header packet of the unit in the last block is transmitted, the CID record deletion packet is transmitted.

  This will be specifically described below. First, the process of the transmission terminal 1 will be described. Since the processing of the attribute information generation unit 12, the unit generation unit 13, the download header addition unit 14, and the IP packet generation unit 15 of the transmission terminal 1 is the same as that of the first embodiment, description thereof is omitted here.

  When the full packet packet / compressed header packet generation unit 16 receives the IP packet of the file 1 from the IP packet generation unit 15, the IP data flow is specified to determine the CID, and the CID record including the CID, IP header, and UDP header Is newly generated and stored in the CID table 10. Further, the full header packet / compressed header packet generation unit 16 inputs the unit of the block number BN = 0, 2, 4,... (Even block number BN including 0) in the IP packet of the file 1. When the previous IP packet of attribute information is input, the full header packet shown in FIGS. 15 (1) and 15 (3) is generated. When the IP packet of the attribute information before inputting the unit of the block number BN = 1, 3, 5... (Odd block number BN) is input, the compression shown in FIGS. Generate a header packet. On the other hand, when the unit IP packet is input, the compressed header packet shown in FIGS. 15 (2) and 15 (4) is generated. In the case where the attribute information is divided into a plurality of pieces by the attribute information generation unit 12 and the IP packet of the attribute information just before the unit of the block number BN = 0, 2, 4 is input, A full header packet is generated only for the top attribute information of the divided attribute information, and a compressed header packet is generated for the other attribute information. Further, the full header packet / compressed header packet generation unit 16 deletes the generated CID record from the CID table 10 when the generation of all the full header packets and the compressed header packet is completed. The specific method for generating the full header packet and the compressed header packet by the full header packet / compressed header packet generation unit 16 has already been described, and is omitted here.

  The control packet generator 17 reads and stores the CID record newly stored by the full header packet / compressed header packet generator 16 from the CID table 10 and recognizes that the CID record has been deleted from the CID table 10. At this time, as shown in FIGS. 7 and 8, a CID record deletion packet including the CID of the stored CID record is generated.

  The transmission control unit 18 inputs the full header packet of the attribute information generated by the full header packet / compressed header packet generation unit 16 and the compressed header packet of the unit, and the CID record deletion packet generated by the control packet generation unit 17 Enter. Then, as shown in FIG. 11, the transmission control unit 18 alternately transmits the full header packet of attribute information and the compressed header packet of the unit, and the compressed header packet of the attribute information and the compressed header packet of the unit alternately for each block. Then, after transmitting the compressed header packet of the unit in the last block, the CID record deletion packet is transmitted. As described above, when attribute information is divided into a plurality of pieces by the attribute information generation unit 12 and when the attribute information immediately before the unit having the block number BN = 0, 2, 4 is transmitted, a plurality of pieces of attribute information are transmitted. The full header packet is transmitted only for the first attribute information among the attribute information divided into two, and the compressed header packet is transmitted for the other attribute information.

  When the file 2 is subsequently transmitted, the same processing as that for transmitting the file 1 is performed.

  Next, processing of the receiving terminal 2 will be described. When the reception control unit 21 of the reception terminal 2 receives the packet of the file 1 transmitted by the transmission terminal 1, the full header packet (block number BN = 0, 2, 4,...) Based on the CID_header_type (CID header type).・ Full header packet of previous attribute information), compressed header packet (block number BN = 1, 3, 5,..., Compressed header packet of previous attribute information, unit compressed header packet, attribute information divided Is attribute information other than the head) and CID record deletion packet.

  Since the processing of the control packet processing unit 22, the full header packet processing unit 23, the compressed header packet processing unit 24, the download header analysis unit 25, and the file restoration unit 26 is the same as that of the first embodiment, description thereof is omitted here.

  As described above, according to the second embodiment, the transmission terminal 1 transmits attribute information necessary for restoring a file in the reception terminal 2 as a full header packet when transmitting the same file. That is, the transmission terminal 1 alternately transmits a full header packet of attribute information and a compressed header packet of a plurality of units, and a compressed header packet of attribute information and a compressed header packet of a plurality of units for each block, After transmitting a compressed header packet of a plurality of units, a CID record deletion packet is transmitted. The receiving terminal 2 receives the full header packet of the attribute information, generates a new CID record, stores it in the CID table 20, and generates an IP packet from the full header packet of the attribute information to acquire the attribute information. . Then, the file body is acquired from the compressed header packet of the unit received thereafter. As a result, when the receiving terminal 2 receives a packet of attribute information necessary for restoring the file, it is not necessary to discard the attribute information packet, and the attribute information of the file can be reliably acquired. Become.

Example 3
Next, Example 3 will be described. In the third embodiment, when transmitting the same file, the attribute information necessary for restoring the file in the receiving terminal 2 is transmitted as a compressed header packet after the transmitting terminal 1 transmits the CID record update packet. .

  FIG. 12 is a diagram illustrating the transmission order of each packet according to the third embodiment. As shown in FIG. 12, when transmitting the same file, a CID record update packet, a compressed header packet of attribute information, and a compressed header packet of a unit are transmitted for each block in this order, and the compressed header packet of the unit in the final block is transmitted. After being transmitted, a CID record deletion packet is transmitted.

  This will be specifically described below. First, the process of the transmission terminal 1 will be described. Since the processing of the attribute information generation unit 12, the unit generation unit 13, the download header addition unit 14, and the IP packet generation unit 15 of the transmission terminal 1 is the same as that of the first embodiment, description thereof is omitted here.

  When the full packet packet / compressed header packet generation unit 16 receives the IP packet of the file 1 from the IP packet generation unit 15, the IP data flow is specified to determine the CID, and the CID record including the CID, IP header, and UDP header Is newly generated and stored in the CID table 10. Further, the full header packet / compressed header packet generator 16 generates the compressed header packet shown in FIGS. 15 (2) and (4) in both cases when the IP packet of the attribute information and the IP packet of the unit are input. . Here, a full header packet is not generated. Even when the attribute information generating unit 12 divides the attribute information into a plurality of pieces, the compressed header packet is generated for all the attribute information. Further, the full header packet / compressed header packet generator 16 deletes the generated CID record from the CID table 10 when the generation of all the compressed header packets is completed. The specific method for generating the compressed header packet by the full header packet / compressed header packet generator 16 has already been described, and will not be described here.

  The control packet generator 17 reads the CID record newly stored by the full header packet / compressed header packet generator 16 from the CID table 10 and generates the CID record update packet shown in FIG.

  Further, the control packet generator 17 reads out and stores the CID record newly stored by the full header packet / compressed header packet generator 16 from the CID table 10 and confirms that the CID record has been deleted from the CID table 10. When recognized, as shown in FIGS. 7 and 8, a CID record deletion packet including the CID of the stored CID record is generated.

  The transmission control unit 18 inputs the compressed header packet of the attribute information and the compressed header packet of the unit generated by the full header packet / compressed header packet generation unit 16 and the CID record update packet generated by the control packet generation unit 17 And a CID record deletion packet. Then, as shown in FIG. 12, the transmission control unit 18 transmits a CID record update packet, a compressed header packet of attribute information, and a compressed header packet of a plurality of units in this order for each block, After transmitting the compressed header packet of the unit, a CID record deletion packet is transmitted. As described above, the compressed header packet is transmitted for all attribute information even when the attribute information is divided into a plurality of pieces by the attribute information generation unit 12. This is the same for all blocks.

  When the file 2 is subsequently transmitted, the same processing as that for transmitting the file 1 is performed.

  Next, processing of the receiving terminal 2 will be described. When the reception control unit 21 of the reception terminal 2 receives the packet of the file 1 transmitted from the transmission terminal 1, the reception control unit 21 compresses the compressed header packet (the compressed header packet of the attribute information, the compressed header packet of the unit) based on the CID_header_type (CID header type). Packet), CID record update packet, and CID record deletion packet.

  The control packet processing unit 22 inputs the CID record update packet distinguished by the reception control unit 21, extracts the CID, IPv4, 6_header_wo_length, and UDP_header_wo_length from the CID record update packet, and the CID record including the CID, IP header, and UDP header Is stored in the CID table 20.

  The compressed header packet processing unit 24 receives the compressed header packet of the attribute information and the compressed header packet of the unit from the reception control unit 21, extracts the CID that is the compressed header from the compressed header packet, and uses the CID as a key to store the CID table 20. Search and read the IP header and UDP header of the CID record having the same CID. Then, the compressed header packet processing unit 24 removes the CID, SN, and CID_header_type (CID header type) from the compressed header packet, adds the length calculated from the “data length” field of the TLV, and further calculates the checksum. The IP packet is generated and output. Since the CID record is already stored in the CID table 20 by the control packet processing unit 22, the CID of the compressed header packet can be restored to the correct header information and an IP packet can be generated. The compressed header packet processing unit 24 outputs IP packets in that order in accordance with the SN of the compressed header packet. Thereby, the compressed header packet processing unit 24 inputs the compressed header packet of the attribute information, and generates the IP packet of the attribute information using the CID table 20 in which a new CID record is already stored by the CID record update packet. Therefore, it is not necessary to discard the input attribute information.

  The control packet processing unit 22 inputs the CID record deletion packet distinguished by the reception control unit 21 and deletes the CID record indicated by the CID from the CID table 20.

  Since the processing of the download header analysis unit 25 and the file restoration unit 26 is the same as that of the first embodiment, the description thereof is omitted here.

  As described above, according to the third embodiment, the transmission terminal 1 transmits the CID record update packet after transmitting the CID record update packet to the attribute information necessary for restoring the file in the reception terminal 2 during the same file transmission. Transmitted as a packet. That is, the transmitting terminal 1 transmits a CID record update packet, a compressed header packet of attribute information, and a compressed header packet of a plurality of units in this order for each block, and after transmitting a compressed header packet of a plurality of units in the final block. CID record deletion packet is transmitted. The receiving terminal 2 receives the CID record update packet, generates a new CID record, stores it in the CID table 20, and then receives a compressed header packet of attribute information. And the receiving terminal 2 produces | generates an IP packet using the new CID record preserve | saved in the CID table 20 from the compression header packet of this attribute information, and acquires attribute information. As a result, when the receiving terminal 2 receives a packet of attribute information necessary for restoring the file, it is not necessary to discard the attribute information packet, and the attribute information of the file can be reliably acquired. Become.

The present invention has been described with reference to the embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the technical idea thereof. For example, in the above embodiment, the transmission terminal 1 transmits the attribute information for each block. However, depending on the number of blocks constituting the file, it is necessary to transmit the attribute information in a block other than the block number BN = 0. There is no. Specifically, when the number of blocks is small (when the block size is large), the frequency of transmitting attribute information is increased. On the other hand, when the number of blocks is large (when the block size is small ), the attribute information is transmitted less frequently and the attribute information is transmitted for each of the plurality of blocks. Further, the attribute information may be transmitted only once in the first block and may not be transmitted after the second block. Similarly, the CID record update packet may be transmitted at the same frequency as when attribute information is transmitted.

  Moreover, in the said Example, although the unit production | generation part 13 of the transmission terminal 1 produced | generated the parity unit from each data unit for every column direction and row direction, it may not necessarily depend on the transmission quality of the one-way transmission line 3. There is no need to generate a parity unit. Further, the FEC method does not need to generate a parity unit by aligning data units two-dimensionally, and a method of generating redundant data, that is, a parity unit by a Reed-Solomon code or a Raptor code may be used. The present invention is not limited to the FEC method.

  Further, the above-described embodiment can be applied to the transmission system using the above-mentioned FLUTE. In this case, the transmission terminal 1 does not include the download header adding unit 14 illustrated in FIG. 2, and the IP packet generation unit 15 performs “TFID”, “block number BN”, “ Data corresponding to “sequence number SN” is set in the FLUTE header of the FLUTE packet shown in FIG. Specifically, the IP packet generation unit 15 sets data corresponding to “TFID” serving as a label for uniquely identifying a file to be transmitted in the TOI of the FLUTE header. Further, data corresponding to “block number BN” and “sequence number SN” indicating the packet order is set in the FLUTE header as the FEC Payload ID. Further, when generating the FLUTE packet of attribute information, the IP packet generator 15 sets TOI = 0 in the FLUTE header and sets FDT as attribute information in the FLUTE payload. As in the previous embodiment, the full header packet / compressed header packet generator 16 generates a full header packet and a compressed header packet, and the transmission controller 18 sends each packet in the order shown in FIGS. Send. The receiving terminal 2 does not include the download header analysis unit 25 illustrated in FIG. 9, and the file restoration unit 26 can specify and acquire attribute information and a unit based on the TOI and FEC Payload ID of the FLUTE header. Can be restored to the original file.

  Moreover, in the said Example, as shown in FIG. 2, the transmission terminal 1 is the memory | storage part 11, the attribute information generation part 12, the unit production | generation part 13, the download header addition part 14, the IP packet generation part 15, a full header packet. The compressed header packet generator 16, the control packet generator 17, the transmission controller 18, and the CID table 10 are provided. However, the transmission terminal 1 has a full header packet / compressed header packet generator 16 and a control packet generator 17. In this case, only the transmission control unit 18 and the CID table 10 are provided, and a separate device includes the storage unit 11, the attribute information generation unit 12, the unit generation unit 13, the download header addition unit 14, and the IP packet generation unit 15. Good. In this case, the separate device transmits the generated IP packet to the transmission terminal 1. Then, the transmission terminal 1 receives an IP packet transmitted by a separate device, generates a full header packet or the like, and transmits it to the one-way transmission path 3.

  In the embodiment, as shown in FIG. 9, the receiving terminal 2 includes the reception control unit 21, the control packet processing unit 22, the full header packet processing unit 23, the compressed header packet processing unit 24, and the download header analysis unit 25. , The file restoration unit 26, the storage unit 27, and the CID table 20, but the reception terminal 2 includes a reception control unit 21, a control packet processing unit 22, a full header packet processing unit 23, a compressed header packet processing unit 24, and Only the CID table 20 may be provided, and a separate device may include the download header analysis unit 25, the file restoration unit 26, and the storage unit 27. In this case, the receiving terminal 2 receives a full header packet or the like from the one-way transmission path 3, generates an IP packet, and transmits the IP packet to a separate device. Then, the separate device receives the IP packet transmitted from the receiving terminal 2 and restores the original file using the attribute information.

  Further, in the embodiment, as shown in FIG. 2, the transmission terminal 1 generates the IP packet shown in FIG. 5 in the IP packet generator 15 and the full header packet / compressed header packet generator 16 generates the IP packet. In the example, the IP header and the UDP header are removed from the IP packet generated by the packet generation unit 15 to generate a full header packet or a compressed header packet. However, the transmission terminal 1 may be configured not to include the IP packet generation unit 15. In this case, a CID record generation unit (not shown) generates in advance a CID record composed of various data such as an IP header and a UDP header necessary for generating an IP packet for each IP data flow. The data is stored in the CID table 10 with the configuration shown. That is, instead of generating an IP packet to which an IP header and a UDP header are added, the header information is stored in the CID table 10 in advance. Then, the full header packet / compressed header packet generation unit 16 reads out the header information from the CID table 10, generates the full header packet or the compressed header packet shown in FIGS. 15 to 18, and outputs it to the transmission control unit 18. To do. The specific method for generating the full header packet and the compressed header packet is as described above. The full header packet processing unit 23 and the compressed header packet processing unit 24 of the receiving terminal 2 do not generate and output an IP packet, but a packet that does not include an IP header and a UDP header, that is, a download header and a unit ( Or a packet including attribute information).

It is a figure which shows schematic structure of the transmission system with which the transmission terminal and receiving terminal by embodiment of this invention are used. It is a block diagram which shows the structure of a transmission terminal. It is a figure which shows the structure of attribute information. It is a figure which shows the structure of a download header. It is a figure which shows the structure of the IP packet output from an IP packet generation part. (1) is a figure which shows the structure of the CID record update packet of IPv4. (2) is a diagram showing a configuration of an IPv6 CID record update packet. It is a figure which shows the structure of a CID record deletion packet. It is a figure which shows the structure of the CID record deletion packet which deletes a some CID record. It is a block diagram which shows the structure of a receiving terminal. It is a figure explaining the transmission order of each packet by Example 1. FIG. It is a figure explaining the transmission order of each packet by Example 2. FIG. It is a figure explaining the transmission order of each packet by Example 3. FIG. It is a figure explaining the header compression system by a full header packet, a compression header packet, and a CID table. (1) is a diagram showing a configuration of an IPv4 CID table. (2) is a diagram showing the configuration of an IPv6 CID table. (1) is a diagram showing a configuration of an IPv4 full header packet. (2) is a diagram showing a configuration of an IPv4 compressed header packet. (3) is a diagram illustrating a configuration of an IPv6 full header packet. (4) is a diagram showing a configuration of an IPv6 compressed header packet. It is a figure which shows the structure of IPv4_header_wo_length in the full header packet of IPv4. It is a figure which shows the structure of IPv6_header_wo_length in the full header packet of IPv6. It is a figure which shows the structure of UDP_header_wo_length in the full header packet of IPv4 and IPv6. It is a figure which shows the structure of a FLUTE packet.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Sending terminal 2 Receiving terminal 3 Unidirectional transmission path 10, 20 CID table 11, 27 Storage part 12 Attribute information generation part 13 Unit generation part 14 Download header addition part 15 IP packet generation part 16 Full header packet / compressed header packet generation part 17 Control packet generator 18 Transmission controller 21 Reception controller 22 Control packet processor 23 Full header packet processor 24 Compressed header packet processor 25 Download header analyzer 26 File restoration unit

Claims (6)

When transmitting a plurality of units in which file attribute information and a file body are divided as the same IP data flow, header information for the IP data flow is used as a context identifier (CID) for specifying the IP data flow. In the transmission terminal that replaces and compresses the header and transmits the compressed header packet including the CID,
A CID table composed of CID records including the CID and header information;
CID is determined based on header information for the IP data flow, a CID record including the CID and header information is generated and stored in the CID table, and a full header packet of attribute information including the CID and header information is generated. And a full header packet / compressed header packet generator for generating a compressed header packet of a unit including the CID and a compressed header packet of attribute information including the CID, and reading out the CID from the CID table;
The full header packet of attribute information generated by the full header packet / compressed header packet generator and the compressed header packet of the unit are transmitted in this order, and then the compressed header packet of the attribute information and the compressed header packet of the unit are transmitted. A transmission control unit that transmits in this order, and repeats transmission of the full header packet of the attribute information and the compressed header packet of the unit, and transmission of the compressed header packet of the attribute information and the compressed header packet of the unit. A transmitting terminal characterized by. When transmitting a plurality of units in which file attribute information and a file body are divided as the same IP data flow, header information for the IP data flow is used as a context identifier (CID) for specifying the IP data flow. In the transmission terminal that replaces and compresses the header and transmits the compressed header packet including the CID,
A CID table composed of CID records including the CID and header information;
CID is determined based on header information for the IP data flow, a CID record including the CID and header information is generated and stored in the CID table, the CID is read from the CID table, and the unit including the CID is compressed. A compressed header packet generating unit that generates a compressed header packet of attribute information including a header packet and the CID;
A control packet generator for generating a CID record update packet for writing a CID record including the CID and header information in a CID table provided on the side receiving the compressed header packet;
The CID record update packet generated by the control packet generator is transmitted, and then the compressed header packet of attribute information and the compressed header packet of the unit generated by the compressed header packet generator are transmitted in this order, A transmission terminal comprising: a transmission control unit that repeats transmission of a CID record update packet and transmission of the compressed header packet of the attribute information and the compressed header packet of the unit. Under a transmission system in which a plurality of units in which file attribute information and a file main body are divided are transmitted as the same IP data flow, header information for the IP data flow is a context identifier for identifying the IP data flow ( In the receiving terminal that receives the compressed header packet that has been replaced by (CID) and is header-compressed and transmitted,
A CID table composed of CID records including the CID and header information;
The full header packet of the attribute information including the CID and the header information and the compressed header packet of the unit including the CID are received in this order, and then the compressed header packet of the attribute information including the CID and the compressed header of the unit including the CID Packets are received in this order, and the reception of the full header packet of the attribute information and the compressed header packet of the unit and the reception of the compressed header packet of the attribute information and the compressed header packet of the unit are repeated to distinguish the received packets A reception control unit;
For the full header packet of the attribute information distinguished by the reception control unit, a CID record including the CID and header information in the full header packet of the attribute information is written to the CID table, and the IP data from the full header packet of the attribute information A full header packet processing unit for generating a packet of attribute information constituting the flow;
For the compressed header packet of the unit distinguished by the reception control unit, the header information is read from the CID table using the CID in the compressed header packet of the unit, and the packet of the unit constituting the IP data flow is generated. A compressed header packet processing unit that reads out header information from the CID table using a CID in the compressed header packet of the attribute information, and generates a packet of attribute information constituting the IP data flow, with respect to the compressed header packet of the attribute information; A receiving terminal comprising: Under a transmission system in which a plurality of units in which file attribute information and a file main body are divided are transmitted as the same IP data flow, header information for the IP data flow is a context identifier for identifying the IP data flow ( In the receiving terminal that receives the compressed header packet that has been replaced by (CID) and is header-compressed and transmitted,
A CID table composed of CID records including the CID and header information;
Receiving the CID record update packet including the CID and header information, and subsequently receiving the compressed header packet of the attribute information including the CID and the compressed header packet of the unit including the CID in this order; A reception control unit that repeats reception and reception of the compressed header packet of the attribute information and the compressed header packet of the unit, and distinguishes the received packet;
A control packet processing unit that writes a CID record including a CID and header information in the CID record update packet to the CID table for the CID record update packet distinguished by the reception control unit;
For the compressed header packet of the attribute information distinguished by the reception control unit, the header information is read from the CID table using the CID in the compressed header packet of the attribute information, and the packet of the attribute information constituting the IP data flow is generated And a compressed header packet processing unit that reads out header information from the CID table using the CID in the compressed header packet of the unit and generates a packet of the unit constituting the IP data flow for the compressed header packet of the unit; A receiving terminal comprising: A transmission system comprising the transmission terminal according to claim 1 and the reception terminal according to claim 3. A transmission system comprising the transmitting terminal according to claim 2 and the receiving terminal according to claim 4.

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