JP6857103B2 - File distribution system and method - Google Patents

Description

The present invention relates to a file distribution system and a 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 widespread use of terminals and data distribution servers for downloading large amounts of data such as high-quality still images and high-quality moving images, and services for transferring large amounts of data, high-speed download communication is required.

Download communication can be expected to increase in speed by using a higher-speed communication access standard. Currently popular communication access standards 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. There is, and communication of up to about 1 Gbps can be used. Further, as communication access standards that are expected to become widespread in the future, wireless LAN standards IEEE802.11ac, IEEE802.11ay, and 5G (5th generation mobile communication system) (3GPP), which provide a maximum transmission speed of 6.93 Gbps for wireless access, and 20 Gbps, IEEE802.1.3e, which can provide a maximum communication speed of 10 Gbps or more for short-range wireless access, and 10G-EPON (10Gigabit-Ethernet PON), which provides a maximum transmission speed of 10 Gbps for wired access, 10G-PON (10Gigabit-PON) ( There are ITU-T G.987), etc., and the speed of download communication is expected to increase.

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

As a conventional technique for speeding up download communication in a distribution service such as video data, the one described in Non-Patent Document 1 is known. Non-Patent Document 1 relates to research for realizing high-speed download by Multipath-HTTP (Multipath-Hypertext Transfer Protocol) (Ranger request: see Non-Patent Document 2) and MPTCP (Multipath TCP). According to Non-Patent Document 1, Multipath-HTTP may have higher performance than MPTCP (see Fig. 13 of the same document).

MEC (Multi-Access Edge Computing) described in Non-Patent Document 4 utilizes a server of an edge network closer to a terminal than cloud computing as an edge server for holding (caching) distribution data, resulting in tight download access. It is a technology that can speed up download communication by avoiding it. Since MEC can reduce the communication delay time between the terminal and the server, protocols such as TCP (Transfer Control Protocol) and QUIC (Quick UDP Internet Connections), whose communication speed depends on the communication delay time, were used. The effect of speeding up communication can be expected. Download communication can be speeded up by using a high-speed communication access standard and MEC.

Further, as another conventional technique, those described in Non-Patent Document 3 are known. What is described in Non-Patent Document 3 is a short-range wireless transfer technology called TransferJet (registered trademark) assuming a communication distance of several cm.

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 it cannot be done unless all the mechanisms such as parallel file download, file integration, and address resolution are implemented in the terminal. In addition, 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 that the servers or servers on the LTE side and Wi-Fi (registered trademark) side are up to each server. If there is a bottleneck in the network, there is a problem that the speed cannot be increased. Further, when there is only one server of the other party for parallel download, the processing capacity of that 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 of Non-Patent Document 4, it is necessary to hold (cache) a copy of a data file (content) in advance on many servers closer to the user terminal, and a file that is not frequently downloaded is stored. In order to increase the speed by holding the data on the edge server including the data, there is a problem that a huge amount of storage must be prepared on the edge server of MEC.

Further, by using the short-range wireless communication technology described in Non-Patent Document 3, it is possible to speed up the download to the terminal, but for the contents that are not stored in advance in the server that implements the short-range wireless communication technology, The transfer throughput of the distribution server and the network to the distribution server becomes a bottleneck, and there is a problem that the 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 closer to the available bandwidth of a user terminal even if there are limits or restrictions on the distribution capacity of the file distribution server or the network through which the file is distributed. The purpose is to provide a file distribution system and method capable of this.

In order to achieve the above object, the present invention is arranged between the file distribution server and the user terminal in a file distribution system including a plurality of file distribution servers and user terminals that provide a file distribution service. The edge server includes a plurality of partial file download units that download a part of the file as a partial file from one of the plurality of file distribution servers, and a download process when a download request is received from the user terminal. The number of parallelizations is determined, the download target location is specified for the partial file download unit for the number of parallelizations, and the download is instructed. The integrated processing unit is provided with an integrated processing unit that distributes to the user terminal, and the integrated processing unit downloads each partial file download unit when the total size of the downloaded partial files exceeds the first threshold value from the start of download. When the size of the file is instructed to be increased and the total size of the downloaded partial files becomes greater than or equal to the second threshold value larger than the first threshold value, the partial file download section is downloaded by another partial file download section. It is characterized by instructing a download target that overlaps with the target.

According to the present invention, it is possible to provide a high throughput closer to the available bandwidth of the user terminal even if the distribution capacity of the file distribution server or the network through which the file is distributed is limited or limited.

Configuration diagram of the 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 illustrating chunk resizing process Diagram illustrating chunk resizing process Processing flow of integrated processing unit that explains chunk size change processing Processing flow of integrated processing unit that explains chunk size change processing Processing flow of integrated processing unit that explains chunk size change processing Diagram illustrating chunk redundancy processing The figure explaining the increase processing of a partial download function The figure explaining the reduction process of a partial download function Graph for primary evaluation of chunk file size Configuration diagram of the file distribution system according to the second embodiment Sequence diagram of the file distribution system according to the 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 An example of management data in the IP address management section of the integrated download function Configuration diagram of the file distribution system according to the third 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, when a download request of a user terminal is triggered, the user terminal or the edge server system speeds up content from one or more content servers according to the line band actually available to the user terminal. It is to be downloaded in parallel.

More specifically, an edge server that parallelizes download communication to the file distribution server in response to the download request of the user terminal 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 and a copy thereof to the user terminal, and includes each distributed file distribution server in the distributed file distribution service. For example, in a 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 a copy of the original file obtained from the original server.

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

In addition, the edge server selects the file distribution server to be used for parallel download from the list of one or more IP addresses of the file distribution server, performs partial download, and is a line during communication between the user terminal and the edge server. It is possible to change the number of file distribution servers 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 parallel download of chunks (specifically, depending on the total number of chunks that have been downloaded). And quickly complete the parallel download.

In addition, the integrated download function of the edge server sends packets to the user terminal with a maximum transmission buffer size larger than that of the file distribution server and congestion control that does not consider fairness, so that the download can be performed in a wider band than the file distribution server. Make it possible.

In addition, the integrated download function of the edge server intervenes 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]
The file distribution system according to the 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 plurality of original / CDN servers 100 and DNS (Domain Name System) servers 200, which are file distribution servers, are arranged in a network 10 such as the Internet.

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

The DNS server 200 is a name resolution server that resolves the name related to the file distribution service by the original / CDN server 100 (here, the name of the original / CDN server 100) and responds to the address of the original / CDN server 100. Note that the address that the DNS server 200 responds to in response to a name resolution request is not always unique. That is, the DNS server 200 can respond to different addresses in response to a name resolution request having the same name, depending on the type and standard of the file distribution service. In the response processing of different addresses, for example, the address of each original / CDN server 100 can be different 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 geographically or in terms of network distance can be returned in consideration of the position of the requesting device in the network and the like. The DNS server 200 may be an authoritative DNS server or a cache DNS server.

The user terminal 1 is housed in a telecommunications carrier network (not shown) via an access line 20. The standard of the access line 20 and the network standard of the telecommunications carrier network are not required. That is, the telecommunications carrier network may be a mobile communication network or a fixed communication network. In FIG. 1, the user terminal 1 is housed in a telecommunications carrier network by a wireless access line 20, and the movement of the user terminal 1 causes a plurality of different standards such as a low-speed RAT (Radio Access Technology) area 25 and a high-speed RAT area 26. It exemplifies that the access line of is available. The telecommunications carrier network is connected to the network 10 where the original / CDN server 100 is located.

As shown in FIG. 1, the file distribution system according to the present invention includes an edge server 300 deployed on a communication path between the original / CDN server 100 and the user terminal 1. The deployment location of the edge server 300 may be, for example, in a telecommunications carrier network such as a base station or an edge router accommodating a 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 function") 310 and an integrated download function (hereinafter referred to as "integrated DL function") 320. There is. Each function of the edge server 300 may be implemented by hardware, or a program may be installed and implemented on a computer. Further, the edge server 300 may be mounted integrally with the relay function in the base station, the edge router, or the like, or may be mounted individually. Further, as will be described later, the edge server 300 may be distributed and deployed in each functional unit. For example, some partial download functions 310 can be placed on the core network of the carrier network instead of on the edge.

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

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

The integrated DL function 320 of the edge server 300 collects and integrates chunk files from a plurality of partial DL functions 310 (step (4) in FIG. 1), and transfers the files to the user terminal 1 at 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 receives from each original / CDN server 100 at high speed with a smaller RTT (Round-Trip Time), the plurality of partial DL functions 310 are geographically divided and deployed. Further, for the server that implements the integrated DL function 320 and the partial DL function 310, the maximum transmission buffer size of the OS is made larger than that of the original / CDN server 100, and the congestion control algorithm is changed for a wider band, so that the partial DL function 310 It is possible to improve the throughput between the integrated DL function 320 and 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 wide band RAT (step S1).

In the present embodiment, the number of partial DL functions 310 to be used first by the integrated DL function 320, that is, the number of parallelizations is determined, triggered by the download request of the user terminal 1, and chunks are made to the partial DL functions 310 for the number of parallelizations. Instruct to download the file (steps S2 to S6). The plurality of partial DL functions 310 of the edge server 300 acquire the IP addresses of the plurality of originals / CDN servers 100 (steps S7 to S12).

The plurality of partial DL functions 310 of the edge server 300 make partial download requests to the plurality of originals / CDN servers 100 and acquire chunk files (steps S13 to S18). After acquiring the chunk file download result from the partial DL function 310, the integrated DL function 320 performs as many partial download tasks as the partial DL function 310, which has a faster reception speed, by giving an instruction to download chunk files that have not been assigned a task. Can be done (steps S19-S24).

The integrated DL function 320 of the edge server 300 collects and integrates chunk files from a 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 delivers the chunk file to the integrated DL function 320, the partial DL function 310 deletes the chunk file (steps S29 to S31).

Next, the details of the 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 when acquiring a partial file from the integrated DL function 320, and temporarily holds the chunk acquisition result and the chunk buffer. The chunk file is transmitted to the integrated DL function 320.

The original / CDN server processing unit 312 acquires the 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 integrates the DL function 320. Send to. Further, the original / CDN server processing unit 312 solves the original / server address by using the DNS server 200. The acquired chunk file is temporarily stored in the chunk buffer unit 313.

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

Next, the details of the integrated DL function 320 according to 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 integrated 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 files, and transmits the chunk file to the user terminal 1. It should be noted that the user terminal 1 is not aware that it was a 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 (parallelization number), the chunk file size, and each partial DL function 310 to be downloaded in parallel. 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 band 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 gives an instruction for partial download to each partial DL function 310, and receives the original / CDN server 100 address, chunk acquisition result, and chunk file from each partial DL function 310, and performs integrated processing. It is transmitted to the unit 322.

The details of the 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 change process.

Downloading of one section of the user terminal from the edge server 300 can be started only after the edge server 300 partially acquires the file from the original / CDN server 100. Therefore, if the file is acquired in a large chunk size, the user terminal 1 can download the file. The download start is delayed. On the other hand, if the chunk size is small, the number of times the procedure for acquiring the partial file between the original / CDN server 100 and the edge server 300 is increased increases, and the throughput of the partial download decreases.

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

An example of the chunk size change processing in the integrated processing unit 322 of the integrated DL function 320 will be described with reference to the flowcharts of FIGS. 7 to 9. This processing example is a flowchart example in which the chunk size is changed for the first half, the middle stage, and the second half in the integrated processing unit 322 of the integrated DL function 320. In the latter half of chunk acquisition, it is possible to make the download process redundant to speed up the completion. Here, an example of changing the chunk size and making the download process redundant (described later) will be described.

As shown in FIG. 7, when the integrated processing unit 322 receives the download request of the user terminal 1, the integrated processing unit 322 assigns the original / CDN server 100 to be downloaded to each partial DL function 310 (steps S101 to S102). The integrated processing unit 322 initializes the value X_SUM indicating the total of the downloaded chunk file sizes to zero, sets the chunk size as the parameter for the first half of the parallel download, and parallel downloads the chunk file by each partial DL function 310. The process (see FIG. 8) is carried out (steps S103 to S105). Then, when the value X_SUM becomes equal to or higher than the first threshold value, the period until the value becomes equal to or higher than the second threshold value is set as a chunk size in the parameter for the middle stage of parallel download, and the chunk file is downloaded in parallel by each partial DL function 310. The process (see FIG. 8) is carried out (steps S106 to S109). Then, when the value X_SUM becomes equal to or higher than the second threshold value, the chunk size is set to the parameter for the final stage of parallel download, and the chunk file redundant parallel download process (see FIG. 9) is performed by each partial DL function 310 (see FIG. 9). Steps S106, S110 to S111).

In the parallel download process of steps S105 and S109, as shown in FIG. 8, if there is a free task in the partial DL function 310, the integrated processing unit 322 uses the partial DL function 310 to obtain the size of the chunk file. Download processing for the chunk size set from the total value X is performed (steps S122 and S123). That is, the integrated processing unit 322 gives a partial download instruction to each partial DL function 310 so that the 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 in step S111, as shown in FIG. 9, if there is a free task in the partial DL function 310, the integrated processing unit 322 uses the partial DL function 310 to acquire the chunk file. The chunk size set from the total size value X of the above is duplicated by the partial DL function 310 (steps S132 and S133).

As the first threshold value, for example, a predetermined first ratio X_Th1 [%] is set in the final chunk size total, that is, the value X_ALL indicating the file size of the file related to the 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 redundant processing of the download processing 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 of day, the download task of any of the parallel DL functions 310 is critical in the final chunk download of the plurality of partial DL functions 310. It becomes a pass and the download completion is delayed.

Therefore, in the present embodiment, as shown in FIG. 10, the parallel download task in the latter half of the parallel download is made redundant, and the download file to the user terminal 1 is configured by using the chunk file obtained earlier to complete the download. 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 this processing example, as shown in FIG. 11, when the total band of the partial DL function 310 _{is smaller than the user's RAT band (S RAT} ), 100 original / CDN servers are added, that is, the number of parallelizations is increased. On the other hand, when the total band of the partial DL function 310 _{is larger than the user's RAT band (S RAT} ), the number of original / CDN servers 100 is reduced, that is, the number of parallelizations is reduced. The amount of increase / decrease 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. Note the following equation in _{S k} is the k-th original / CDN server 100 and throughput between the edge server _{300, S RAT} throughput between the edge server 300 and the user terminal 1, a frequent number of servers in _{C 1} a little change of throughput It is a constant that does not change.

Further, for example, when the following equation is satisfied, if, the partial DL number k is decremented by 1. Note the following equation in _{S k} is the k-th original / CDN server 100 and throughput between the edge server _{300, S RAT} throughput between the edge server 300 and the user terminal 1, a frequent number of servers in _{C 2} a little change of throughput It is a constant that does not change.

For the file distribution system according to this embodiment, a primary evaluation was performed by calculation regarding the chunk file size. FIG. 13 is a graph for performing a primary evaluation of chunk file size. This primary evaluation evaluates how many chunk size units the edge server 300 should partially download the HTTP Range request to the original / CDN server 100 to obtain the best performance.

In FIG. 13, the horizontal axis is the chunk file size, and the vertical axis is the download time of the original file. The calculation conditions of the graph in FIG. 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 if the chunk file size is too small, the partial download acquisition is delayed, while if 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 high throughput closer to the available bandwidth of the user terminal even if there are limits or restrictions on the distribution capacity of each file distribution server or the network through which the file distribution server passes. It becomes.

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

Further, it is not necessary to hold the content downloaded by the user terminal in advance on the server of the edge server system closer to the user terminal 1. Specifically, cloud storage files are basically data that each individual has, and are not used by a large number of people, so temporary cache retention on an edge server requires a huge amount of storage resources and is virtually difficult. However, it is possible to speed up the download of content that is not downloaded by such a large number of people.

In addition, the download throughput can be increased without installing a new dedicated parallel download / integration / address resolution application on the user terminal 1.

Here, the problems 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 the parallelization is biased to one in the worst case. Further, since the IP address is acquired after receiving the download request from the user terminal 1, there is a delay corresponding to the start of the parallel download.

[Second Embodiment]
The file distribution system according to the 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 this embodiment, the configurations other than the edge server are the same as those in 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 edge server 300 collects and updates the IP address of the original / CDN server 100 in advance regardless of the trigger of the download request of the user terminal (FIG. 14). Step (1)).

Then, triggered by the download request of the user terminal 1 (step (2) in FIG. 14), the edge server 300 determines the number of parallel downloads, and a portion of the plurality of originals / CDN server 100 having an IP address managed by the DB. Send the download request (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 in geographically different locations or may be deployed in the same location. When the partial DL function 310 receives from each original / CDN server 100 at high speed with a smaller RTT, a plurality of partial DL functions 310 are geographically divided and deployed. Further, for the server that implements the integrated DL function 320 and the partial DL function 310, the maximum transmission buffer size of the OS is made larger than that of the original / CDN server 100, and the congestion control algorithm is changed for a wider band, so that the partial DL function 310 It is possible to improve the throughput between the integrated DL function 320 and 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 the present embodiment, the edge server 300 collects the IP address of the original / CDN server in advance, registers it in the DB, and updates it at regular intervals regardless of the download request of the user terminal 1 (steps S51 to 56).

Here, it is assumed that the user terminal 1 is in the wide band RAT (step S61). Upon the download request of the user terminal 1, the edge server 300 determines the number of partial downloads, and instructs the plurality of partial DL functions 310 to partially download from the plurality of originals / CDN server 100 of the IP address managed by the DB ( Steps S62 to S66). The plurality of partial DL functions 310 of the edge server 300 make partial download requests to the plurality of originals / CDN servers 100 and acquire chunk files (steps S67 to S72). After acquiring the chunk file download result from the partial DL function 310, the integrated DL function 320 executes as many partial DL tasks as the partial DL function 310 having a faster reception speed by giving an instruction to download the chunk file to which no task is assigned. Can be done (steps S73-S78).

The integrated DL function 310 of the edge server 300 collects and integrates chunk files from a 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 delivers the chunk file to the integrated DL function 320, the partial DL function 310 deletes the chunk file (steps S83 to S85).

Next, the details of the 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 shown 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 when acquiring a partial file from the integrated DL function 320, and temporarily holds the chunk acquisition result and the chunk buffer. The chunk file is transmitted to the integrated DL function 320.

The original / CDN server processing unit 312 acquires the 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 integrates the DL function 320. Send to. Further, the original / CDN server processing unit 312 solves the original / server address by using the DNS server 200. The acquired chunk file is temporarily stored in the chunk buffer unit 313.

The chunk buffer unit 313 is an area for temporarily holding the chunk file acquired from the original / CDN server 100. The chunk buffer unit 313 has a function of deleting chunk files that have 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. By acquiring the IP address with each partial DL function 310 instead of the integrated DL function 320, when the partial DL function 310 is geographically distributed and deployed, it is geographically close to the partial DL function 310 and each partial DL. It becomes possible to acquire the IP address of the original / CDN server 100 capable of faster partial download from the function 310.

Next, the details of the integrated DL function 320 according to 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 integrated processing unit 322, a partial DL function communication processing unit 323, an IP address management unit 324, and an IP address acquisition unit 325. There is.

The terminal communication processing unit 321 receives the download request from the user terminal 1, integrates the chunk files, and transmits the chunk file to the user terminal 1. It should be noted that the user terminal 1 is not aware that it was a 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 the IP address management unit 324, and the number (parallelization number), chunk size, and each partial DL to be downloaded in parallel by the partial DL function 310. The chunk portion 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 band 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 gives an instruction for partial download to each partial DL function 310, and receives the original / CDN server 100 address, chunk acquisition result, and chunk file from each partial DL function 310, and performs integrated processing. It is transmitted to the unit 322.

The IP address management unit 324 manages the IP address of the original / CDN server 100 used by the integrated processing unit 322, the TTL (Time To Live) related to each IP address, the throughput information, and the like. FIG. 18 shows an example of management data in the IP address management unit 324.

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. Further, by acquiring the IP address of the original / CDN server 100 held by the partial DL function 310 from each partial DL function 310, it is possible to acquire a plurality of IP addresses of the original / CDN server 100 that are geographically different. In addition, only one of the acquisition methods may be used.

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

According to the file distribution system according to the first 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 becomes complicated as compared with the first embodiment.

[Third Embodiment]
The file distribution system according to the 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 this embodiment, the configurations other than the edge server are the same as those in 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. The other functional units of the edge server 300 are arranged in the telecommunications 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 download request of the user terminal. (Step (1) in FIG. 19).

Then, when the user terminal 1 makes a request to the integrated DL function 320 using a short-range wireless transfer technology such as TransferJet (step (2) in FIG. 19), the integrated DL function 320 determines the number of parallel downloads. It is controlled to partially download from the plurality of originals / CDN server 100 having the IP address 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 a 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 by using 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 transmitting side and the receiving side are point-to-point at a short distance of several cm and are not affected by the communication of other terminals. High-speed transfer can be realized.

Next, the details of the integrated DL function 320 according to 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 integrated 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 the download request from the user terminal 1 by the short-range wireless transfer technology, integrates the chunk file into the user terminal 1, and transmits the file to the user terminal 1 by the short-range wireless transfer technology. To do.

The functions of the integrated DL function 320 for other configurations are the same as those of the second embodiment, and thus the description thereof will be omitted. The IP address acquisition unit 325 and the IP address management unit 324 in this embodiment do not have to be mounted on the same server as the integrated processing unit 322, and may be physically separated from each other.

Further, since the configuration and functions of the partial DL function 310 in the present embodiment and the sequence of the file distribution system are the same as those in the second embodiment, the description thereof will be omitted. Further, in the present embodiment, the chunk size change processing of the integrated processing unit 322, the operation flowchart example, the redundancy processing, and the increase / decrease processing of the partial DL function 310 in the integrated processing unit 322 are the same as those of the first embodiment. Therefore, the description is omitted.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited thereto. 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 in each of the processes described in the above embodiment, the parameters, the threshold value, the constant, and the like used in the algorithm are examples, and the present invention can be implemented by other algorithms and the like.

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 unit 312 ... Original / CDN server processing unit 313 ... Chunk buffer Unit 314 ... IP address management unit 320 ... Integrated DL function 321 ... Terminal communication processing unit 322 ... Integrated 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 (6)

In a file distribution system equipped with multiple file distribution servers and user terminals that provide file distribution services,
An edge server arranged between the file distribution server and the user terminal is provided.
The edge server
A plurality of partial file download units that download a part of the file as a partial file from one of the plurality of file distribution servers, and
When the download request is received from the user terminal, the number of parallelized download processes is determined, the partial file download unit corresponding to the parallelized number is instructed to download by designating the download target location, and the partial file download is performed. It is equipped with an integrated processing unit that combines the partial files acquired from the unit and delivers them to the user terminal of the request source .
When the total size of the downloaded subfiles exceeds the first threshold value from the start of download, the integrated processing unit instructs each of the subfile download units to increase the size of the subfiles to be downloaded, and further downloads. When the total size of the partial files becomes greater than or equal to the second threshold value larger than the first threshold value, the partial file download section is instructed to download targets that overlap with the download targets of the other partial file download sections. File delivery system. The plurality of partial file download units are provided with server address resolution means for resolving the address of the file distribution server from the name related to the file distribution service by using a name resolution server, respectively, in response to a download instruction from the integrated processing unit. The file distribution system according to claim 1, wherein a part of a 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 means for holding the address of one or more file distribution servers for the name related to the file distribution service.
The file distribution system according to claim 1, wherein the integrated processing unit specifies an address of a file distribution server acquired from the address management means and instructs the partial file download unit to download the file. The file distribution system according to any one of claims 1 to 3 , wherein the integrated processing unit changes the number of parallelizations in the process of download processing. The user terminal is housed in a telecommunications carrier network via an access line.
A claim that the edge server is characterized in that the integrated processing unit is arranged on the user terminal side with respect to the access line, and the partial file download processing unit is arranged on the telecommunications carrier network. The file distribution system according to any one of 1 to 5. In the file distribution method in a file distribution system equipped with a plurality of file distribution servers and user terminals that provide a file distribution service,
The file distribution system includes an edge server arranged between the file distribution server and the user terminal.
When the integrated processing unit of the edge server receives the download request from the user terminal, the number of parallelized download processes is determined, and the partial file download unit of the edge server is used as the partial file download unit for the number of parallelized files. On the other hand, the step of specifying the download target location and instructing the download,
A step wherein the partial file download section of the edge server, to download a portion of the file from one of said plurality of file distribution server based on an instruction from the integration processing unit as a partial file,
A step in which the integrated processing unit of the edge server combines the partial files acquired from the partial file download unit and delivers them to the user terminal of the request source .
When the total size of the downloaded partial files from the start of download becomes equal to or greater than the first threshold value, the integrated processing unit instructs each of the partial file download units to increase the size of the partial files to be downloaded, and further downloads. When the total size of the partial files becomes greater than or equal to the second threshold value larger than the first threshold value, the partial file download section is provided with a step of instructing the partial file download section to have a download target that overlaps with the download target of the other partial file download section. A file distribution method characterized by that.

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