JP2019032680A - File distributing system and method - Google Patents

Abstract

To provide file distributing system and method capable of providing a high throughput further close to the available bandwidth of a user terminal even if there is a limit and a restriction in a distribution capability of a file distributing server and in a network through for distribution.SOLUTION: An edge server 300 is placed between an original document/CDN server 100 and a user terminal 1. The edge server 300 includes: a plurality of partial DL functions 310; and an integration DL function 320. Each partial DL function 310 downloads a part (chunk) of a file from the original document/CDN server 100. The integration DL function 320 integrates chunk files by the respective partial DL functions 310, and distributes the integrated file to the user terminal 1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a file distribution system and method in which a user terminal downloads a file related to content from one or more content servers on a network such as the Internet.

  In recent years, with the spread of terminals and data distribution servers that download large amounts of data such as high-quality still images and high-quality moving images, and services that transfer large amounts of data, the speed of download communication has been demanded.

  Download communication can be expected to speed up by using a faster communication access standard. Communication access standards currently in widespread use include LTE (Long Term Evolution) (3GPP: 3rd Generation Partnership Project) for wireless access and GE-PON (Gigabit Passive-Optical Network) (ITU-T G.984) for wired access. Communication of up to about 1 Gbps can be used. Further, as a communication access standard that is expected to become widespread in the future, in wireless access, wireless LAN standards IEEE802.11ac, IEEE802.11ay, 20Gps that provide a maximum transmission rate of 6.93 Gbps (5GP) (3GPP), IEEE802.15.3e, which can provide communication speeds of up to 10Gbps for short-range wireless access, and 10G-EPON (10Gigabit-Ethernet PON), 10G-PON (10Gigabit-PON), which provides maximum transmission speed of 10Gbps for wired access ITU-T G.987) and the like, and speeding up of download communication is expected.

  However, the communication access standard is only one factor that determines the speed of download communication. When there is a bottleneck in the control of the communication protocol, or when the processing capacity of the network device between the distribution server and the terminal and the server is tight Cannot achieve high-speed download communication.

  Non-Patent Document 1 is known as a conventional technique for speeding up download communication in a distribution service for video data and the like. Non-Patent Document 1 relates to research for realizing high-speed download by Multipath-HTTP (Multipath-Hypertext Transfer Protocol) (Range request: see Non-Patent Document 2) and MPTCP (Multipath TCP). According to Non-Patent Document 1, Multipath-HTTP is said to be able to perform more than MPTCP (see FIG. 13).

  MEC (Multi-Access Edge Computing) described in Non-Patent Document 4 uses an edge network server that is closer to the terminal than cloud computing as an edge server for holding distribution data (cache). By avoiding this technology, the speed of download communication can be increased. MEC uses a protocol such as TCP (Transfer Control Protocol) or QUIC (Quick UDP Internet Connections) whose communication speed depends on the communication delay time because the communication delay time between the terminal and the server can be reduced. The effect of speeding up communication can be expected. By using a high-speed communication access standard and MEC, it is possible to increase the speed of download communication.

  Moreover, what was described in the nonpatent literature 3 is known as another prior art. What is described in Non-Patent Document 3 is a short-distance wireless transfer technology called TransferJet (registered trademark) that assumes a communication distance of several centimeters.

Juhoon Kim, 4 others, "Multi-source Multipath HTTP (mHTTP): A Proposal", ACM SIGMETRICS Performance Evaluation Review, October 2013 R. Fielding, 2 others, "Hypertext Transfer Protocol (HTTP / 1.1): Range Requests", RFC7233, Internet Engineering Task Force (IETF), June 2014 "TransferJet White Paper Revision 1.2", TransferJet Consortium, September 2015 Multi-access Edge Computing, http://www.etsi.org/technologies-clusters/technologies/multi-access-edge-computing, Jun. 2007.

  However, although Non-Patent Document 1 describes that Multipath-HTTP is useful, there is a problem that all the mechanisms such as parallel file download, file integration, and address resolution cannot be implemented in the terminal. Further, in the research content described in Non-Patent Document 1, only the communication interfaces such as LTE and Wi-Fi (registered trademark) are parallelized, so the servers or servers on the LTE side and the Wi-Fi (registered trademark) side respectively. If there is a bottleneck in this network, there is a problem that cannot be accelerated. In addition, when there is one server that performs parallel download, the processing capacity of the server becomes a bottleneck, and there is a problem that the download throughput cannot be improved even if the line bandwidth of the terminal is sufficient.

  Further, in the method of speeding up download by MEC in Non-Patent Document 4, it is necessary to hold (cache) copies of data files (contents) in advance on many servers closer to the user terminal, and files that are not frequently downloaded are stored. In order to increase the speed by holding them in the edge server, there is a problem that a huge amount of storage must be prepared in the edge server of the MEC.

  Moreover, although the download speed to the terminal can be increased by using the short-range wireless communication technology described in Non-Patent Document 3, for content that is not held in advance in the server that implements the short-range wireless communication technology, The transfer throughput of the network to the distribution server and the distribution server becomes a bottleneck, and there is a problem that file download speed cannot be increased.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a high throughput that is closer to the available bandwidth of the user terminal even if the distribution capability of the file distribution server and the network through it are limited or limited. An object of the present invention is to provide a file distribution system and method that can be used.

  In order to achieve the above object, the present invention is arranged between a file distribution server and a user terminal in a file distribution system including a plurality of file distribution servers that provide a file distribution service and a user terminal. An edge server, wherein the edge server downloads a part of the file from one of the plurality of file distribution servers, and the number of download processes in parallel when a download request is received from the user terminal. And specifying the download target location to the partial file download units corresponding to the number of parallelizations, instructing the download, and combining the partial files obtained from the partial file download unit to request the user of the request source And an integrated processing unit that delivers to the terminal It is characterized in.

  According to the present invention, it is possible to provide a high throughput closer to the usable bandwidth of the user terminal even if there are limitations or restrictions on the distribution capability of the file distribution server and the network through which the file distribution server passes.

Configuration diagram of a file distribution system according to the first embodiment Sequence diagram of the file distribution system according to the first embodiment Functional block diagram of the partial download function of the edge server according to the first embodiment Functional block diagram of the integrated download function of the edge server according to the first embodiment Diagram explaining chunk size change processing Diagram explaining chunk size change processing Process flow of the integrated processing unit explaining the chunk size change process Process flow of the integrated processing unit explaining the chunk size change process Process flow of the integrated processing unit explaining the chunk size change process Diagram explaining chunk redundancy processing The figure explaining the increase processing of the partial download function The figure explaining the reduction process of the partial download function Graph for primary evaluation of chunk file size The block diagram of the file delivery system which concerns on 2nd Embodiment Sequence diagram of file distribution system according to second embodiment Functional block diagram of the partial download function of the edge server according to the second embodiment Functional block diagram of the integrated download function of the edge server according to the second embodiment Example of management data in IP address management unit of integrated download function The block diagram of the file delivery system which concerns on 3rd Embodiment Functional block diagram of the integrated download function of the edge server according to the fourth embodiment

  First, the outline of the present invention will be described. In the file distribution system according to the present invention, in response to a download request from a user terminal, the user terminal or the edge server system can quickly transmit content from one or more content servers according to the line bandwidth that can be actually used by the user terminal. Download in parallel.

  More specifically, an edge server that parallelizes download communication to the file distribution server in response to a user terminal download request is deployed between the file distribution server that distributes the original content file and the user terminal. To do. Here, the file distribution server is a server that distributes the original file related to the content or a copy thereof to the user terminal, and includes each distributed file distribution server in the distributed file distribution service. For example, in the CDN, the file distribution server includes not only the original server that distributes the original file, but also a plurality of CDN servers that distribute copies of the original file acquired from the original server.

  The edge server acquires one or more IP addresses of the file distribution server, performs partial download multiple times in units of partial files (hereinafter referred to as “chunks”) for one or more file distributions, To provide high-speed download to user terminals.

  The edge server also selects a file distribution server to be used for parallel download from a list of one or more IP addresses of the file distribution server, performs partial download, and communicates between the user terminal and the edge server. The number of file distribution servers can be changed according to the bandwidth.

  In addition, the edge server starts downloading from the edge server to the user terminal by changing the chunk file size and the number of chunk acquisitions according to the progress of the parallel download of chunks (specifically, the total number of chunks that have been downloaded). And complete parallel downloads quickly.

  In addition, the integrated download function of the edge server performs a packet transmission based on congestion control that does not consider fairness with a maximum transmission buffer size larger than that of the file distribution server to the user terminal, thereby downloading a wider bandwidth than the file distribution server. Make it possible.

  Further, the integrated download function of the edge server enters between communication with the user terminal and communication with the partial download function, and enables conversion of the communication protocol.

  Hereinafter, embodiments of the present invention will be described in detail.

[First Embodiment]
A file distribution system according to a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of a file distribution system according to the first embodiment.

  As shown in FIG. 1, a network 10 such as the Internet includes a plurality of original / CDN servers 100 and a DNS (Domain Name System) server 200 that are file distribution servers.

  In the present embodiment, the original / CDN server 100 is either an original server that distributes an original file that distributes an original file, or a CDN server that distributes an original file or a copy thereof as a file distribution server in a CDN. Means that. Each original / CDN server 100 can distribute the same file having the same content (same content).

  The DNS server 200 is a name resolution server that resolves a name related to the file distribution service by the original / CDN server 100 (here, the name of the original / CDN server 100) and responds with the address of the original / CDN server 100. Here, it should be noted that the address to which the DNS server 200 responds to a name resolution request is not necessarily unique. That is, the DNS server 200 can respond with different addresses to the name resolution request with the same name according to the type / standard of the file distribution service. In response processing of different addresses, for example, different addresses of each original / CDN server 100 can be responded for each response request by round robin. Further, for example, according to the setting of the CDN, the address of the original / CDN server 100 closest to the geographical or network distance can be returned in consideration of the position of the requesting device in the network. The DNS server 200 may be an authoritative DNS server or a cache DNS server.

  The user terminal 1 is accommodated in a communication carrier network (not shown) via the access line 20. The standard of the access line 20 and the network standard of the telecommunications carrier network are not questioned. That is, the communication carrier network may be a mobile communication network or a fixed communication network. In FIG. 1, the user terminal 1 is accommodated in a communication carrier network by a wireless access line 20, and a plurality of different standards such as a low speed RAT (Radio Access Technology) area 25 and a high speed RAT area 26 as the user terminal 1 moves. It is illustrated that the access line can be used. The telecommunications carrier network is connected to the network 10 where the original / CDN server 100 is arranged.

  As shown in FIG. 1, the file distribution system according to the present invention includes an edge server 300 arranged on a communication path between the original / CDN server 100 and the user terminal 1. The location of the edge server 300 may be, for example, in a carrier network such as a base station or an edge router that accommodates the user terminal 1.

  As shown in FIG. 1, the edge server 300 includes a plurality of partial download functions (hereinafter referred to as “partial DL functions”) 310 and an integrated download function (hereinafter referred to as “integrated DL functions”) 320. Yes. Each function of the edge server 300 may be implemented by hardware, or may be implemented by installing a program in a computer. The edge server 300 may be mounted integrally with a relay function in a base station, an edge router, or the like, or may be mounted individually. Further, as described later, the edge server 300 may be provided by distributing each functional unit. For example, some partial download functions 310 can be located in the core network of the carrier network instead of at the edge.

  In the file distribution system according to the present embodiment, triggered by a download request from the user terminal 1 (step (1) in FIG. 1), a plurality of original DL servers / CDN servers from a plurality of partial DL functions 310 of the edge server 300 100 IP addresses are acquired (step (2) in FIG. 1).

  The plurality of partial DL functions 310 of the edge server 300 execute partial download requests to the plurality of original / CDN servers 100 (step (3) in FIG. 1). The partial download process can use, for example, an HTTP RANGE request described in Non-Patent Document 2.

  The integrated DL function 320 of the edge server 300 collects and integrates chunk files from the plurality of partial DL functions 310 (step (4) in FIG. 1), and transfers the files to the user terminal 1 at a high speed (step (5 in FIG. 1). )).

  The integrated DL function 320 and the partial DL function 310 may be deployed in geographically different locations, or may be deployed in the same location or the same server. When the partial DL function 310 is received at a high speed with a smaller RTT (Round-Trip Time) from each original / CDN server 100, the plurality of partial DL functions 310 are geographically divided and deployed. Further, with respect to a server that implements the integrated DL function 320 and the partial DL function 310, the partial DL function 310 is increased by increasing the maximum transmission buffer size of the OS and changing the congestion control algorithm for a wider bandwidth than the original / CDN server 100. It is possible to improve throughput between the integrated DL function 320 and between the integrated DL function 320 and the user terminal 1.

  The flow of file distribution in the file distribution system according to the present embodiment will be described with reference to the sequence chart of FIG. Here, it is assumed that the user terminal 1 is in the broadband RAT (step S1).

  In the present embodiment, triggered by a download request from the user terminal 1, the number of partial DL functions 310 that the integrated DL function 320 uses first, that is, the number of parallelizations is determined, and the partial DL functions 310 corresponding to the number of parallelizations are chunked. A file download instruction is issued (steps S2 to S6). The plurality of partial DL functions 310 of the edge server 300 acquire the IP addresses of the plurality of original / CDN servers 100 (steps S7 to S12).

  The plurality of partial DL functions 310 of the edge server 300 execute partial download requests to the plurality of original / CDN servers 100 and acquire chunk files (steps S13 to S18). The integrated DL function 320 executes a partial download task as much as the partial DL function 310 having a higher reception speed by giving a download instruction of the chunk file to which the task is not assigned after obtaining the download result of the chunk file from the partial DL function 310. (Steps S19 to S24).

  The integrated DL function 320 of the edge server 300 collects and integrates chunk files from the plurality of partial DL functions 310, and transfers the files to the user terminal 1 at high speed (steps S25 to S28). When the partial DL function 310 distributes the chunk file to the integrated DL function 320, the partial DL function 310 deletes the chunk file (steps S29 to S31).

  Next, details of partial DL function 310 in the present embodiment will be described with reference to FIG. FIG. 3 is a functional block diagram of the partial DL function of the edge server according to the first embodiment.

  As shown in FIG. 3, the partial DL function 310 includes an integrated DL function communication processing unit 311, an original / CDN server processing unit 312, and a chunk buffer unit 313.

  The integrated DL function communication processing unit 311 receives a partial download instruction and a file size (chunk size) instruction for acquiring a partial file from the integrated DL function 320, and temporarily holds them in the chunk acquisition result and the chunk buffer. The chunk file to be transmitted is transmitted to the integrated DL function 320.

  The original / CDN server processing unit 312 acquires a chunk file from the original / CDN server 100, calculates the time required to acquire the chunk file from the chunk file request and the communication protocol message of the acquisition completion, and the integrated DL function 320. Send to. Also, the original / CDN server processing unit 312 uses the DNS server 200 to resolve the original / server address. The acquired chunk file is temporarily stored in the chunk buffer unit 313.

  The chunk buffer unit 313 is an area that temporarily holds a chunk file acquired from the original / CDN server 100. The chunk buffer unit 313 has a function of deleting a chunk file that has been transmitted to the integrated DL function 320 in order to save a holding area.

  Next, details of the integrated DL function 320 in the present embodiment will be described with reference to FIG. FIG. 4 is a functional block diagram of the integrated DL function of the edge server according to the first embodiment.

  As shown in FIG. 4, the integrated DL function 320 includes a terminal communication processing unit 321, an integration processing unit 322, and a partial DL function communication processing unit 323.

  The terminal communication processing unit 321 receives the download request from the user terminal 1, integrates the chunk file, and transmits the integrated chunk file to the user terminal 1. It should be noted that the user terminal 1 is not conscious of the chunk download.

  The integrated processing unit 322 cooperates with the terminal communication processing unit 321 and the partial DL function communication processing unit 323, and causes the partial DL function 310 to acquire the number to be downloaded in parallel (the number of parallelization), the chunk file size, and each partial DL function 310. Determine the chunk part. In the determination process, the file transmission speed from the integrated DL function 320 to the user terminal 1 (corresponding to the usable bandwidth of the user terminal 1), the actual information of the file transmission speed from the original / CDN server 100 to each partial DL function 310, etc. Is used.

  The partial DL function communication processing unit 323 instructs partial download to each partial DL function 310, receives the address of the original / CDN server 100, a chunk acquisition result, and a chunk file from each partial DL function 310, and performs integration processing. Transmitted to the unit 322.

  Details of chunk file download processing control using the partial DL function 310 in the integrated DL function 320 will be described below with reference to FIGS. 5 and 6. 5 and 6 are diagrams for explaining the chunk size changing process.

  Downloading the user terminal 1 section from the edge server 300 can be started only after the edge server 300 partially acquires the file from the original / CDN server 100. Download start is delayed. On the other hand, if the chunk size is small, the number of times of performing the partial file acquisition procedure between the original / CDN server 100 and the edge server 300 increases, and the partial download throughput decreases.

  Therefore, in the present embodiment, as shown in FIGS. 5 and 6, in the integrated processing unit 322 in the integrated DL function 320, the chunk size acquired by each partial DL function 310 is made variable (the first half is a chunk file). By setting the size to a smaller size and requesting each partial DL function 310 by setting the size to a larger size after the first half, the throughput of the partial DL is also prevented from being delayed without delaying the start of downloading to the terminal.

  An example of chunk size change processing in the integration processing unit 322 of the integrated DL function 320 will be described with reference to the flowcharts of FIGS. This processing example is a flowchart example in which the chunk size is changed for the first half, the middle, and the second half in the integration processing unit 322 of the integrated DL function 320. In the second half of chunk acquisition, the download process can be made redundant to speed up the completion. Here, an example in which the download process is made redundant (described later) along with the chunk size change will be described.

  As illustrated in FIG. 7, upon receiving the download request from the user terminal 1, the integration processing unit 322 assigns the original / CDN server 100 to be downloaded to each partial DL function 310 (steps S101 to S102). The integration processing unit 322 initializes a value X_SUM indicating the total size of downloaded chunk files to zero, sets the chunk size as a parameter for the first half of parallel download, and downloads chunk files in parallel by the partial DL functions 310. Processing (see FIG. 8) is performed (steps S103 to S105). Then, when the value X_SUM is equal to or greater than the first threshold, the chunk size is set as a parameter for the parallel download mid-period, and the chunk file is downloaded in parallel by each partial DL function 310. Processing (see FIG. 8) is performed (steps S106 to S109). When the value X_SUM is equal to or greater than the second threshold, the chunk size is set as a parameter for the end of parallel download, and the redundant parallel download processing of the chunk file by each partial DL function 310 (see FIG. 9) is performed (see FIG. 9). Steps S106, S110 to S111).

  In the parallel download process in steps S105 and S109, as shown in FIG. 8, the integration processing unit 322 uses the partial DL function 310 to obtain the size of the acquired chunk file if there is a free task in the partial DL function 310. Download processing for the chunk size set from the total value X is performed (steps S122 and S123). That is, the integration processing unit 322 instructs each partial DL function 310 to download partial data so that chunks downloaded by each partial DL function 310 do not overlap each other and are continuous.

  On the other hand, in the redundant parallel download process of step S111, as shown in FIG. 9, the integrated processing unit 322 uses the partial DL function 310 to acquire an acquired chunk file if there is a free task in the partial DL function 310. Download processing for the chunk size set from the total size value X is performed by each partial DL function 310 (steps S132 and S133).

  As the first threshold, for example, a predetermined first ratio X_Th1 [%] is added to a final total chunk size, that is, a value X_ALL indicating a file size of a file related to a download request from the user terminal 1. The multiplied value can be used. Similarly, as the second threshold value, a value obtained by multiplying the value X_ALL by a predetermined second ratio X_Th1 [%] can be used.

  Next, an example of the redundancy process of the download process in the integrated processing unit 322 of the integrated DL function 320 will be described with reference to FIG.

  Since each original / CDN server 100 has a different download throughput and a different download throughput depending on the time zone, the download task of one of the parallel DL functions 310 is critical in the last chunk download of the plurality of partial DL functions 310. It becomes a pass and download completion is delayed.

  Therefore, in the present embodiment, as shown in FIG. 10, the parallel download task in the second half of the parallel download is made redundant, and the download file to the user terminal 1 is configured using the chunk file that can be acquired quickly, thereby completing the download completion. Improve.

Next, an example of processing for increasing or decreasing the partial DL function 310 in the integrated processing unit 322 of the integrated DL function 320 will be described with reference to FIGS. 11 and 12. In the present processing example, as shown in FIG. 11, when the total bandwidth of the partial DL function 310 is smaller than the user's RAT bandwidth (S _RAT ), the number of original / CDN servers 100 is added, that is, the number of parallelization is increased. On the other hand, when the total bandwidth of the partial DL function 310 is larger than the user's RAT bandwidth (S _RAT ), the number of original / CDN servers 100 is reduced, that is, the number of parallelization is reduced. The increase / decrease amount may be a preset constant or may be determined by calculating from the parallel DL throughput and the terminal throughput.

For example, when the following equation is satisfied, the partial DL number k is increased by 3. In the following equation, S _k is the throughput between the k-th original / CDN server 100 and the edge server 300, S _RAT is the throughput between the edge server 300 and the user terminal 1, and C ₁ is the number of servers frequently with a slight change in throughput. This is a constant to keep it from changing.

Also, for example, if the following equation is satisfied, the partial DL number k is decreased by 1. In the following equation, S _k is the throughput between the k-th original / CDN server 100 and the edge server 300, S _RAT is the throughput between the edge server 300 and the user terminal 1, and C ₂ is the number of servers frequently with a slight change in throughput. This is a constant to keep it from changing.

  The file distribution system according to the present embodiment was subjected to a primary evaluation by calculation with respect to the chunk file size. FIG. 13 is a graph for performing a primary evaluation of the chunk file size. This primary evaluation evaluates how much performance can be obtained when the edge server 300 partially downloads an HTTP Range request to the original / CDN server 100 in units of chunk size.

  In FIG. 13, the horizontal axis represents the chunk file size, and the vertical axis represents the download time of the original file. 13 are the original file size: 4 GB, and the average throughput between the original / CDN server and the edge server 300: 200 Mbps (25 MB / s).

  As shown in FIG. 13, it was confirmed that when the chunk file size is too small, partial download acquisition is delayed, whereas when the chunk file size is too large, the download start time of the user terminal 1 is delayed.

  As described above, according to the file distribution system according to the present embodiment, it is possible to provide a high throughput that is closer to the available bandwidth of the user terminal even if the distribution capability of each file distribution server and the network through which it passes are limited or restricted. It becomes.

  Specifically, with the current commercial optical line service (in the future even mobile communication 5G), the terminal can experience high-speed communication only at the measurement site, and the benefits of speeding up with the actual OTT (Over The Top) service However, according to the present invention, the merits of the high-speed line can be actually received by using the actual OTT service, so that the appeal power of the high-speed line service can be improved.

  In addition, it is not necessary to previously store the content downloaded by the user terminal in the server of the edge server system closer to the user terminal 1. Specifically, cloud storage files are basically data held by each individual and are not used by many people, so temporary storage of caches on the edge server requires a huge amount of storage resources and is actually difficult. However, it is possible to speed up the download of contents that are not downloaded by such a large number of people.

  Further, it is possible to increase the download throughput without installing a new dedicated parallel download / integration / address resolution application in the user terminal 1.

  Here, the problem of the file distribution system according to the present embodiment will be examined. In the present embodiment, when the edge server 300 acquires a plurality of IP addresses of the original server from the DNS server 200, the plurality of IP addresses are not necessarily distributed separately. Therefore, it is assumed that the throughput does not increase even if it is parallel to the worst one. In addition, since an IP address is acquired after receiving a download request from the user terminal 1, a delay corresponding to the start of parallel download occurs.

[Second Embodiment]
A file delivery system according to a second embodiment of the present invention will be described with reference to the drawings. FIG. 14 is a configuration diagram of a file distribution system according to the second embodiment. In the present embodiment, the configuration other than the edge server is the same as that of the first embodiment. Here, the differences will be described in detail.

  In the file distribution system according to the present embodiment, as shown in FIG. 14, the IP address of the original / CDN server 100 is collected and updated in advance by the edge server 300 regardless of the trigger of the download request of the user terminal (FIG. 14). Step (1)).

  Then, in response to a download request from the user terminal 1 (step (2) in FIG. 14), the edge server 300 determines the number of parallel downloads, and is a part of the multiple original / CDN server 100 having an IP address managed by the DB. A download request is transmitted (step (3) in FIG. 14).

  The integrated DL function 320 of the edge server 300 collects and integrates chunk files (block files) from the plurality of partial DL functions 310 (step (4) in FIG. 14), and transfers the files to the user terminal 1 at high speed (FIG. 14). Step (5)).

  The integrated DL function 320 and the partial DL function 310 may be deployed at geographically different locations or at the same location. When the partial DL function 310 is received from each original / CDN server 100 at a high speed with a smaller RTT, the plurality of partial DL functions 310 are geographically divided and deployed. Further, with respect to a server that implements the integrated DL function 320 and the partial DL function 310, the partial DL function 310 is increased by increasing the maximum transmission buffer size of the OS and changing the congestion control algorithm for a wider bandwidth than the original / CDN server 100. It is possible to improve throughput between the integrated DL function 320 and between the integrated DL function 320 and the user terminal 1.

  The flow of file distribution in the file distribution system according to the present embodiment will be described with reference to the sequence chart of FIG.

  In this embodiment, regardless of the download request from the user terminal 1, the IP address of the original / CDN server is collected in advance by the edge server 300 and registered in the DB, and updated at regular intervals (steps S51 to S56).

  Here, it is assumed that the user terminal 1 is in the broadband RAT (step S61). In response to a download request from the user terminal 1, the edge server 300 determines the number of partial downloads, and instructs a plurality of partial DL functions 310 to perform partial downloads from a plurality of original / CDN servers 100 having IP addresses managed by the DB ( Steps S62 to S66). The plurality of partial DL functions 310 of the edge server 300 execute partial download requests to the plurality of original / CDN servers 100 and acquire chunk files (steps S67 to S72). The integrated DL function 320 executes the partial DL tasks as much as the partial DL function 310 having a higher reception speed by giving a download instruction of the chunk file to which the task is not assigned after obtaining the download result of the chunk file from the partial DL function 310. (Steps S73 to S78).

  The integrated DL function 310 of the edge server 300 collects and integrates chunk files from the plurality of partial DL functions 310, and transfers the files to the user terminal 1 at high speed (steps S79 to S82). When the partial DL function 310 distributes the chunk file to the integrated DL function 320, the partial DL function 310 deletes the chunk file (steps S83 to S85).

  Next, details of partial DL function 310 in the present embodiment will be described with reference to FIG. FIG. 16 is a functional block diagram of the partial DL function of the edge server according to the second embodiment.

  As illustrated in FIG. 16, the partial DL function 310 includes an integrated DL function communication processing unit 311, an original / CDN server processing unit 312, a chunk buffer unit 313, and an IP address management unit 314.

  The integrated DL function communication processing unit 311 receives a partial download instruction and a file size (chunk size) instruction for acquiring a partial file from the integrated DL function 320, and temporarily holds them in the chunk acquisition result and the chunk buffer. The chunk file to be transmitted is transmitted to the integrated DL function 320.

  The original / CDN server processing unit 312 acquires a chunk file from the original / CDN server 100, calculates the time required to acquire the chunk file from the chunk file request and the communication protocol message of the acquisition completion, and the integrated DL function 320. Send to. The original / CDN server processing unit 312 uses the DNS server 200 to resolve the original / server address. The acquired chunk file is temporarily stored in the chunk buffer unit 313.

  The chunk buffer unit 313 is an area that temporarily holds a chunk file acquired from the original / CDN server 100. The chunk buffer unit 313 has a function of deleting a chunk file that has been transmitted to the integrated DL function 320 in order to save a holding area.

  The IP address management unit 314 transmits the IP address acquired by the partial DL function 310 to the integrated DL function 320 asynchronously with the download request of the user terminal 1. When the partial DL function 310 is geographically distributed by acquiring the IP address in each partial DL function 310 instead of the integrated DL function 320, each partial DL function 310 is geographically close. It is possible to acquire the IP address of the original / CDN server 100 that can be downloaded at a higher speed from the function 310.

  Next, details of the integrated DL function 320 in the present embodiment will be described with reference to FIG. FIG. 17 is a functional block diagram of the integrated DL function of the edge server according to the second embodiment.

  As shown in FIG. 17, the integrated DL function 320 includes a terminal communication processing unit 321, an integration processing unit 322, a partial DL function communication processing unit 323, an IP address management unit 324, and an IP address acquisition unit 325. Yes.

  The terminal communication processing unit 321 receives the download request from the user terminal 1, integrates the chunk file, and transmits the integrated chunk file to the user terminal 1. It should be noted that the user terminal 1 is not conscious of the chunk download.

  The integrated processing unit 322 cooperates with the terminal communication processing unit 321, the partial DL function communication processing unit 323, and the IP address management unit 324, and performs the number of parallel downloads by the partial DL function 310 (parallelization number), chunk size, and each partial DL The chunk part to be acquired by the function 310 is determined. In the determination process, the file transmission speed from the integrated DL function 320 to the user terminal 1 (corresponding to the usable bandwidth of the user terminal 1), the actual information of the file transmission speed from the original / CDN server 100 to each partial DL function 310, etc. Is used.

  The partial DL function communication processing unit 323 instructs partial download to each partial DL function 310, receives the address of the original / CDN server 100, a chunk acquisition result, and a chunk file from each partial DL function 310, and performs integration processing. Transmitted to the unit 322.

  The IP address management unit 324 manages the IP address of the original / CDN server 100 used in the integration processing unit 322, TTL (Time To Live) related to each IP address, throughput information, and the like. An example of management data in the IP address management unit 324 is shown in FIG.

  The IP address acquisition unit 325 acquires a plurality of IP addresses of the original / CDN server 100 from the DNS server 200 asynchronously with the download request of the user terminal 1. Also, by acquiring the IP address of the original / CDN server 100 held by the partial DL function 310 from each partial DL function 310, a plurality of geographically different original / CDN server 100 IP addresses can be acquired. Only one of the acquisition methods may be used.

  In the present embodiment, the chunk size changing process in the integrated processing unit 322, the operation flowchart example, the redundancy process, and the increase / decrease process of the partial DL function 310 in the integrated processing unit 322 are the same as those in the first embodiment. Is omitted.

  According to the file distribution system according to the present embodiment, since the IP address of the original / CDN server 100 is managed by the edge server 300, the problems mentioned in the first embodiment can be solved. However, there is a problem that the configuration of the edge server 300 is complicated as compared with the first embodiment.

[Third Embodiment]
A file delivery system according to a third embodiment of the present invention will be described with reference to the drawings. FIG. 19 is a configuration diagram of a file distribution system according to the third embodiment. In the present embodiment, the configuration other than the edge server is the same as that of the second embodiment. Here, the differences will be described in detail.

  In the present embodiment, as shown in FIG. 19, the integrated DL function 320 of the edge server 300 is arranged on the user terminal 1 side with respect to the access line 20. Other functional units in the edge server 300 are arranged in the communication carrier network on the original / CDN server 100 side with respect to the access line 20 as in the second embodiment.

  In the file distribution system according to the present embodiment, as in the second embodiment, the edge server 300 collects and updates the IP address of the original / CDN server 100 in advance, regardless of the trigger of the user terminal download request. (Step (1) in FIG. 19).

  Then, when the user terminal 1 makes a request to the integrated DL function 320 using short-range wireless transfer technology such as TransferJet (step (2) in FIG. 19), the integrated DL function 320 determines the number of parallel downloads, Control is performed so that partial download is performed from a plurality of original / CDN servers 100 having IP addresses managed by the DB (step (3) in FIG. 19).

  The integrated DL function 320 of the edge server 300 collects and integrates chunk files (block files) from the plurality of partial DL functions 310 (step (4) in FIG. 19), and uses the short-range wireless transfer technology to the user terminal 1. The file is transferred at high speed (step (5) in FIG. 19).

  The integrated DL function 320 uses TCP / IP for communication with the partial DL function 310, but it is also possible to use a transfer protocol other than TCP / IP using the short-range wireless transfer technology for communication with the user terminal 1. . The short-range wireless transfer technology used between the user terminal 1 and the integrated DL function 320 is stable because the transmission side and the reception side are a short distance of several centimeters and are not point-to-point and are not affected by the communication of other terminals. High-speed transfer can be realized.

  Next, details of the integrated DL function 320 in the present embodiment will be described with reference to FIG. FIG. 20 is a functional block diagram of the integrated DL function of the edge server according to the third embodiment.

  As shown in FIG. 20, the integrated DL function 320 includes a terminal proximity communication processing unit 326, an integration processing unit 322, a partial DL function communication processing unit 323, an IP address management unit 324, and an IP address acquisition unit 325. ing.

  The terminal proximity communication processing unit 326 receives a download request from the user terminal 1 using the short-range wireless transfer technology, and integrates the chunk file with the user terminal 1 and transmits the file to the user terminal 1 using the short-range wireless transfer technology. To do.

  The functions of the other components in the integrated DL function 320 are the same as those in the second embodiment, and a description thereof will be omitted. Note that the IP address acquisition unit 325 and the IP address management unit 324 in the present embodiment may not be mounted on the same server as the integration processing unit 322 and may be physically separated.

  Also, the configuration and functions of the partial DL function 310 in this embodiment and the sequence of the file distribution system are the same as those in the second embodiment, and thus the description thereof is omitted. Furthermore, in the present embodiment, the chunk size change processing of the integration processing unit 322, the operation flowchart example, the redundancy processing, and the increase / decrease processing of the partial DL function 310 in the integration processing unit 322 are the same as those in the first embodiment. Therefore, explanation is omitted.

  As mentioned above, although embodiment of this invention was explained in full detail, this invention is not limited to this. For example, in the above embodiment, an example in which chunk size change processing, redundancy processing, and parallelization number increase / decrease processing are combined has been described, but any one or any combination may be used. Further, the algorithm, parameters, threshold values, constants, and the like used in each of the processes described in the above embodiment are merely examples, and the present invention can be implemented even with other algorithms.

DESCRIPTION OF SYMBOLS 1 ... User terminal 10 ... Network 20 ... Access line 100 ... Original / CDN server 200 ... DNS server 300 ... Edge server 310 ... Partial DL function 311 ... Integrated DL function communication processing part 312 ... Original / CDN server processing part 313 ... Chunk buffer Unit 314 ... IP address management unit 320 ... Integrated DL function 321 ... Terminal communication processing unit 322 ... Integration processing unit 323 ... Partial DL function communication processing unit 324 ... IP address management unit 325 ... IP address acquisition unit 326 ... Terminal proximity communication processing unit

Claims (8)

In a file delivery system comprising a plurality of file delivery servers and user terminals that provide a file delivery service,
An edge server arranged between the file distribution server and the user terminal;
The edge server is
A plurality of partial file download units for downloading a part of the file from one of the plurality of file distribution servers;
When a download request is received from the user terminal, the number of download processes to be parallelized is determined, and the partial file download unit is instructed to download by designating a download target portion for the number of parallel files. A file distribution system comprising: an integrated processing unit that combines the partial files acquired from the unit and distributes the partial files to the requesting user terminal. The plurality of partial file download units each include server address resolution means for resolving the address of the file distribution server from a name related to a file distribution service using a name resolution server, and in response to a download instruction from the integration processing unit The file distribution system according to claim 1, wherein a part of the file is downloaded from a file distribution server having an address resolved by the server address resolution means. The edge server includes an address management unit that holds an address of one or more file distribution servers for a name related to a file distribution service,
The file distribution system according to claim 1, wherein the integration processing unit designates an address of a file distribution server acquired from the address management unit and instructs the partial file download unit to download. The file distribution system according to any one of claims 1 to 3, wherein the integration processing unit changes a size of a part of a file to be downloaded to each of the partial file download units in a download process. The integration processing unit instructs the partial file download unit in the course of download processing to download a target that overlaps with a download target in another partial file download unit. The file distribution system described. The file distribution system according to any one of claims 1 to 5, wherein the integration processing unit changes the parallelization number in the course of download processing. The user terminal is accommodated in a carrier network via an access line;
2. The edge server, wherein the integrated processing unit is arranged on the user terminal side with respect to the access line, and the partial download processing unit is arranged in a telecommunications carrier network. 7. The file distribution system according to any one of 6 to 6. In a file delivery method in a file delivery system comprising a plurality of file delivery servers and user terminals that provide a file delivery service,
The file delivery system includes an edge server disposed between the file delivery server and the user terminal,
When the integration processing unit of the edge server receives a download request from the user terminal, it determines the number of parallelizations of the download processing, and the partial file download unit of the edge server includes the partial file download unit for the number of parallelizations. Specifying the download target location and instructing the download,
The partial file download unit of the edge server downloads a part of the file from one of the plurality of file distribution servers based on an instruction from the integration processing unit;
A file distribution method comprising: an integration processing unit of the edge server combining the partial files acquired from the partial file download unit and distributing the combined files to the requesting user terminal.

Images