KR101252947B1 - Method and apparatus for push-pull hybrid streaming adaptive to video chunk distribution - Google Patents

Abstract

A method and apparatus are provided for sharing a file played by streaming in a P2P network. The chunks that make up the file may be delivered in a particular manner based on the rareness or buffer map information of the chunks. Each of the chunks may be transferred between peers in a push or pull fashion depending on the rarity. In addition, depending on the buffer map gap, the entire chunks may be delivered in a push or pull manner, the same scheme may be used for all peers in the network, and a different scheme may be used for each of the peers.

Description

TECHNICAL AND APPARATUS FOR PUSH-PULL HYBRID STREAMING ADAPTIVE TO VIDEO CHUNK DISTRIBUTION

The following embodiments are directed to a method and apparatus for adaptively streaming to a video chunk distribution.

The Web 2.0 craze calls for "participation, sharing, and openness" and calls for a paradigm shift to the Internet.

At the heart of this Web 2.0 craze, P2P television, commonly referred to as peer-to-peer (P2P) streaming, is showing remarkable growth. P2P TV, or P2P streaming, delivers / shares a video stream over a P2P overlay network.

Today, leading multimedia sites, such as YouTube, for the most part, provide services based on a Client / Server (C / S) model. For these sites, the cost of establishing a network infrastructure for IP multicast and paying a Content Delivery Network (CDN) server is pointed out as a problem.

Although these Internet media sites are enjoying great success, the success is based on the assumption that video streams of 300 to 500 Kbps are provided. Considering the IPTV service having a higher quality than such a video stream, the scalability problem of video transmission based on the C / S model should be reconsidered.

The IP multicast-based model is pointed out as a disadvantage of the scaling problem and the deployment problem of the multicast protocol. Server-based or CDN-based models are pointed out as a disadvantage of the transmission cost,

An alternative to this problem is P2P based multi-media streaming. P2P based multimedia streaming has an advantage in cost and can be easily deployed because it does not require the support of Internet routers and network infrastructure.

The peer that downloads the stream requests the other peer to upload the stream. By this request, the sum of the upload bandwidths of the peers constituting the P2P network can be the total download capacity of the system.

Therefore, P2P TV service has a great advantage of scalability that can overcome the performance bottleneck of the C / S model.

In addition, P2P streaming based on P2P technology can support rich channels, personalized viewing and various terminals.

P2P TV is mainly used to transmit TV channels of Asian countries to the Internet, mainly in China. P2P TVs are also used to retransmit TV channels in North America over the Internet.

However, even if the existing P2P TV service has achieved a limited technical or commercial success, the existing P2P TV service does not provide a satisfactory quality of experience (QoE) to the user.

The gap between the high expectations of users accustomed to existing TV quality and the quality provided by P2P TV is significant. Therefore, from the point of view of P2P TV, it is urgently needed to be competitive with regular IPTV service in the short term, and in the long term, a systematic technical development effort is required to provide service quality comparable to that of conventional TV. do.

There is a big difference from the start between the services of regular IPTV operators that have their own managed, private IP transport networks, and P2P TV services that deliver video over the unmanaged, public Internet. exist.

In particular, the most serious problem of P2P IPTV, the Internet video transmission service, is the delay of program transmission and slow response rate to user request.

In general, P2P streaming service may be classified into a tree-push and a mesh-pull according to the overlay structure.

In a tree-push scheme, video streaming is passed sequentially from parent to child along a preformed tree path. The mesh-pull scheme, on the other hand, has a structure in which peers request and obtain the required video chunks from their neighbors.

Basically, the tree-push method has a disadvantage in that it is difficult to flexibly operate on a peer churn (a phenomenon in which the peer is arbitrarily connected / terminated) and the upload bandwidth utilization of the peers is low. The mesh-pull scheme has problems such as high control message overhead and long start delay time.

In general, the mesh-pull method is preferred to the tree-push method because of the simplicity of the mesh-pull method and the high elasticity to the peer fabric.

One embodiment of the present invention can provide an optional push-pull device and method using a combination of push and pull, which is a method of P2P video streaming.

One embodiment of the present invention can provide a streaming apparatus and method for selectively using push and pull based on the chunk distribution.

According to an aspect of the present invention, in a method in which a node in a P2P network shares a file with neighbor nodes, calculating a rareness of each of one or more chunks included in the file based on buffer map information of the neighbor nodes. Determining a transmission / reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness, and transmitting / receiving each of the selected one or more chunks according to the determined transmission / reception scheme. The buffer map information includes information on whether the neighbor node owns each of the one or more chunks, and the degree of rareness of the chunk is the extent to which each of the one or more chunks spread between the node and the neighbor nodes within the network. The transmission and reception method is a file sharing, push or pull method This method is provided.

The Singapore file sharing method may further include receiving the buffer map information from the neighbor nodes.

Determining a transmission / reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness, wherein the rareness of the one or more chunks is equal to or greater than a first predefined value and is owned by the node. And selecting one chunk as a rare rare chunk, wherein transmitting and receiving each of the selected one or more chunks according to the determined transmission and reception scheme includes the rare rare chunk of the neighboring nodes. And sending to chunks that do not.

Determining a transmission / reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness includes selecting a chunk owned only by the node among the one or more chunks as a high rare chunk. The transmitting and receiving of each of the selected one or more chunks according to the determined transmission and reception scheme may include transmitting the high rare chunk to one or more of the neighboring nodes.

Determining a transmission / reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness, wherein the rareness of the one or more chunks is less than a first predefined value, and the neighboring nodes And selecting a chunk owned by one or more nodes of the node and not owned by the node as a rare chunk, and transmitting and receiving each of the selected one or more chunks according to the determined transmission / reception scheme. Requesting transmission of the rare chunk to a node including the rare chunk, and receiving the rare chunk from the neighboring node.

Determining a transmission / reception scheme for each of one or more selected chunks of the one or more chunks based on the rareness includes selecting as a rare chunk a chunk not owned only by the node of the one or more chunks. The transmitting and receiving of each of the selected one or more chunks according to the determined transmission and reception scheme may include requesting transmission of the rare chunk to one or more nodes of the neighboring nodes and requesting transmission of the rare chunk. And receiving said rare chunk from said one or more nodes.

The file may be a file being played by the node, and determining the transmission / reception scheme of each of the one or more selected chunks of the one or more chunks based on the rareness may include a distance from a playback point of the file. And selecting a particular chunk of the one or more chunks as a rare chunk based on the rareness, and transmitting and receiving each of the selected one or more chunks according to the determined transmission / reception scheme may include: Requesting transmission of the rare chunk to one or more nodes, and receiving the rare chunk from the one or more nodes for which the transmission of the rare chunk is requested.

According to another aspect of the present invention, in a node sharing a file with neighboring nodes in a P2P network, a rareness of calculating a rareness of each of one or more chunks included in the file based on buffer map information of the neighboring nodes. A calculator, a transmission / reception scheme determining unit determining a transmission / reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness, and a transmission / reception to transmit / receive each of the selected one or more chunks according to the determined transmission / reception scheme. And the buffer map information includes information on whether the neighbor node owns each of the one or more chunks, and the degree of rareness of each of the one or more chunks between the node and the neighbor nodes. The degree of spread in the network, and the transmission and reception method is a push method It is provided with a pull method, a network node.

The transmission / reception scheme determining unit may select a chunk owned by the node as a rare rare chunk having the rareness greater than or equal to a first predefined value among the one or more chunks, and the transceiver unit selects the rare rare chunk as the neighboring node. Among them, it can be transmitted to the chunk not including the rare chunked.

The transmission / reception scheme determination unit may select as a rare chunk a rare chunk of the one or more chunks that is less than a first predefined value and is owned by one or more nodes of the neighbor nodes and is not owned by the node. The transceiver may request a node including the rare chunk of the neighbor nodes to transmit the rare chunk, and receive the rare chunk from the neighbor node.

According to another aspect of the present invention, in a method in which a node in a P2P network shares a file with neighbor nodes, calculating a buffer map gap based on buffer map information of the neighbor nodes and buffer map information of the node. Determining a transmission / reception scheme of one or more selected chunks of the one or more chunks based on the buffer map gap, and transmitting / receiving the selected one or more chunks according to the determined transmission / reception scheme. And information on whether the neighbor node owns each of the one or more chunks, and the buffer map gap means a gap between buffer map information of the neighbor nodes and buffer map information of the node. A file sharing method is provided, either push or pull.

Computing a buffer map gap based on the buffer map information of the neighbor nodes and the buffer map information of the node, the buffer map of all the neighbor nodes and the buffer map of the node for all of the neighbor nodes based on The method may include calculating the buffer map gap, and determining the transmission / reception scheme of one or more selected chunks of the one or more chunks based on the buffer map gap, wherein the buffer map gap is equal to or greater than a predefined value. And determining a pull method as a transmission / reception method of the one or more selected chunks, and determining a push method as the transmission / reception method of the one or more selected chunks when the buffer map gap is less than a predefined value.

The predefined value may be determined based on the size of the buffer map of the node and the number of neighboring nodes.

If the buffer map gap is greater than or equal to a predefined value, determining a pull method as a transmission / reception method of the one or more selected chunks may include: rare of each of the one or more chunks included in the file based on buffer map information of the neighbor nodes; Calculating a degree and determining the selected one of the one or more chunks whose rareness is equal to or greater than a first predefined value and which sends the chunk owned by the node in a pull manner; The rareness of the chunks may indicate the extent to which each of the one or more chunks has spread within the network between the node and the neighbor nodes.

Computing a buffer map gap based on the buffer map information of the neighbor nodes and the buffer map information of the node, for each of the neighbor nodes based on the buffer map of each of the neighbor nodes and the buffer map of the node. The method may include calculating a buffer map gap, and determining a transmission / reception scheme of one or more selected chunks of the one or more chunks based on the buffer map gap, wherein the buffer map gap of each of the neighboring nodes is determined. And determining a transmission / reception scheme of the one or more selected chunks to each of the neighbor nodes based on the method.

The method of transmitting and receiving the one or more selected chunks to each of the neighbor nodes based on the buffer map gap of each of the neighbor nodes may include: a neighbor of which the buffer map gap is greater than or equal to a predefined value. Determining a pull method for a node as a transmission / reception method of the one or more selected chunks and a push method for the neighbor node whose buffer map gap among the neighbor nodes is less than the predefined value. And determining as.

According to another aspect of the present invention, in a node in a P2P network sharing a file with neighboring nodes, a buffer map gap calculation for calculating a buffer map gap based on buffer map information of the neighbor nodes and buffer map information of the node. A transmission / reception scheme determining unit configured to determine a transmission / reception scheme of one or more selected chunks of the one or more chunks based on the buffer map gap, and a transmission / reception unit configured to transmit / receive the selected one or more chunks according to the determined transmission / reception scheme. Buffer map information includes information on whether the neighbor node owns each of the one or more chunks, and the buffer map gap means a gap between buffer map information of the neighbor nodes and buffer map information of the node, The transmission and reception method is a push method or a pull method, the network node is first It is.

The buffer map gap calculator may calculate the buffer map gap for all of the neighbor nodes based on the buffer maps of all of the neighbor nodes and the buffer map of the node, and the transmission / reception scheme determining unit may set the buffer map gap to be the first. If the value is equal to or greater than one predefined value, the pull method may be determined as a transmission / reception method of the one or more selected chunks, and if the buffer map gap is less than the first predefined value, the push method may be determined as a transmission / reception method of the one or more selected chunks. have.

The network node may further include a rareness calculator configured to calculate a rareness of each of the one or more chunks included in the file based on buffer map information of the neighbor nodes, and the transmission / reception scheme determining unit may include the one or more chunks. Wherein the rareness is greater than or equal to a second predefined value, and the chunk owned by the node can be determined as the selected chunk to send in a pull manner, wherein the rareness of the chunk is determined by the one or more nodes between the node and the neighboring nodes. Each of the chunks may represent the extent to which it spreads within the network.

The buffer map gap calculator may calculate the buffer map gap for each of the neighbor nodes based on the buffer map of each of the neighbor nodes and the buffer map of the node, and the transmission / reception scheme determining unit may calculate the gap between the neighbor nodes. The transmission and reception method of the one or more selected chunks to each of the neighbor nodes may be determined based on the buffer map gap.

The transmission / reception scheme determination unit may determine a pull scheme as a transmission / reception scheme of the one or more selected chunks among the neighbor nodes having the buffer map gap of the neighbor nodes greater than or equal to a first predefined value, and the buffer map among the neighbor nodes. A push method may be determined as a transmission / reception scheme of the one or more selected chunks for a neighbor node whose gap is less than the first predefined value.

An alternative push-pull device and method are provided that use a mix of push and pull, which is a method of P2P video streaming.

Streaming devices and methods are provided that selectively use push and pull based on the chunk distribution.

1 illustrates a per-chunk push-pull scheme according to an embodiment of the present invention.
2 illustrates a first peer-to-peer push-pull scheme according to an embodiment of the present invention.
3 illustrates a second peer-to-peer push-pull scheme according to an embodiment of the present invention.
4 is a flowchart of a method in which a node in a P2P network shares a file using a per-chunk push-pull scheme according to an embodiment of the present invention.
5 is a structural diagram of a node using a chunk-by-chunk push-pull method according to an embodiment of the present invention.
6 is a flowchart of a method in which a node in a P2P network shares a file using a per-chunk push-pull scheme according to an embodiment of the present invention.
7 is a structural diagram of a node using a chunk-by-chunk push-pull method according to an embodiment of the present invention.
8 illustrates an effective download ratio and a total download ratio according to an embodiment of the present invention.
9 shows a miss ratio according to an embodiment of the present invention.
FIG. 10 illustrates a diffusion rate and a diffusion delay according to an embodiment of the present invention. FIG.
11 illustrates an overhead ratio according to an embodiment of the present invention.
12 illustrates a push fraction according to an example of the present invention.

In general, a terminal providing a video by screening is classified into IPTV and Internet TV according to whether a transmission network used by the terminal is a private IP network or a public Internet. However, in terms of multimedia streaming technology, this distinction may not have much meaning. Accordingly, in the embodiments of the present invention to be described below, IPTV, Internet TV, and P2P TV are used as the same meaning except when explicit division is required.

In addition, in the embodiments of the present invention to be described later, the peer, node and terminal means entities that can perform the transmission and reception in the network, and have the same meaning.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to or limited by the embodiments. Like reference symbols in the drawings denote like elements.

Representative chunk transmission schemes used in P2P TVs include push and pull.

1) In the push method, the sender is basically the subject of the chunk selection. In other words, the chunk selected by the sender is unilaterally sent to the receiver. Therefore, no unnecessary delay occurs according to the request of the receiver. However, there is a possibility that two (or more than one) peers (senders) simultaneously send the same chunk to one peer (receiver). This collision due to duplicate transmission wastes resources.

2) In pull mode, the receiver is the subject of the chunk selection. The receiver informs the sender what chunks are needed and receives the required chunks. Therefore, the pull method completely eliminates the collision problem caused by the push method, but generates time waste due to the overhead of the chunk request.

An optional push-pull scheme according to an embodiment of the present invention described below is a new live streaming protocol that combines the advantages of the push (i.e. tree-push) scheme and the pull (i.e. mesh-pull) scheme.

That is, the selective push-pull method may select and use the push and pull in a timely manner based on the mesh. In an embodiment of the present invention to be described below, a method of using a chunk distribution diagram as a criterion for selecting one of two methods is proposed.

Similar to the present invention, GridMedia is a representative method of simultaneously using push and pull.

In a GridMedia system, a peer initially operates in a pull manner, but then requests substreams from a neighbor to allow data to be delivered from the neighbor in a push manner.

In this way, GridMedia reduces the control message overhead involved in the pull method, and in addition to using the pull method in the process of switching to the push method, the system performance is also used as a backup for lost chunks. To improve.

However, in grid media, the transmission through the push method must be preceded by the transmission process by a certain pool. Thus, grid media is different from the embodiments of the present invention that select push and pull based on the distribution of the chunks.

In addition, while GridMedia focuses on reducing control message overhead, which is a drawback of the mesh approach, embodiments of the present invention focus not only on reducing control message overhead but also on solving conflict problems.

The selective push-pull scheme proposed in the embodiments of the present invention described below appropriately selects pushes and pulls according to the situation based on the measured chunk distribution.

In order to measure the chunk distribution which is a criterion for selecting the push method and the pull method, the rarity and buffer map disparity for each chunk are defined.

1) The rareness of a chunk indicates the extent to which the chunk spreads within the network between peers in the network (ie, a particular peer and the particular peer and neighbor peers). The lower the rareness value of the chunk, the more widely it is.

Here, the peer's neighbors refer to peers that can share chunks with the peer through a P2P network.

As a basic method for calculating the rarity of the chunk, the rarity of the chunk can be the inverse of the replication rate of the chunk measured.

The replication rate of a chunk can be measured by counting how many times it appears in the neighborhood of the chunk. The number of occurrences of a chunk in a neighborhood may be calculated through buffer map information that the neighbors periodically notify (or, upon request) the peer.

The buffer map information is information about each of one or more chunks included in the file. The buffer map information includes information about whether the peer owns each of the one or more chunks the file contains.

Thus, the rareness of the chunks can be calculated by measuring the replication rate of each of the chunks (ie, measuring the chunks and taking the inverse of the measured replication rates) based on the buffer maps of the neighbors owned by the chunks. The figure may be an inverse of the number of appearances of each of the one or more chunks in the peer and the peers' neighboring peers that compute the rareness.

2) Buffer Map Gap means a gap between buffer maps of peers. The larger the value of the buffer map gap, the less redundancy between the buffer maps.

The buffer map gap is one of the important indicators affecting P2P streaming performance. The buffer map gap is closely related to the playback persistence and start delay of the peer.

The buffer map gap can be used as one of the important factors in predicting the performance of P2P live streaming. For example, as a reason for the low streaming performance of less popular channels, a buffer map gap is indicated, along with the number of bandwidth peers and the amount of server resources allocated per peer.

A large value of the buffer map gap means that there is little overlap between the buffer maps. Therefore, when the value of the buffer map gap is large, even if chunks are transmitted in a push manner, the probability that the chunks are repeatedly transmitted is low. In addition, when the value of the buffer map gap is large, the delivery using a push may be more advantageous in terms of performance than the delivery using a pool.

Therefore, it can be used as an indicator for selecting the buffer map gap push method and the pull method.

For example, the buffer map gap may be calculated according to Equation 1 below.

Where i and j represent peers neighboring each other. m represents the number of neighbors of peer i. UC _i (j) represents the number of chunks owned by peer j uniquely among peer i's neighbors.

As described above, the optional push-pull scheme selects pushes and pulls based on the measured chunk distribution.

The push method is advantageous when there are few collisions due to redundant transmission because the chunk rareness of the chunks or the buffer map gap between peers is high.

The pull method is advantageous when there are many collisions when the push method is used because the chunk rarity of the chunks is low (i.e., when distributing chunks prevalent in the network), or because the buffer map gap between the pores is low. This is because chunks that are prevalent in the network can be easily obtained by using pools, and if pushes are used to deliver highly distributed (i.e., less rare) chunks, the number of collisions will increase. Bandwidth can be wasted.

Selective push-pull cushions include 1) a chunked push-pull scheme that determines how chunks are sent per chunk based on the chunked rarity described above and 2) a chunk per peer based on the buffer map gap described above. It is divided into a peer-specific push-pull method for determining a transmission method of.

Peer-specific push-pull schemes use pushes in a timely manner, alleviating the collision problem caused by the pushes.

The per-peer push-pull scheme includes a first per-peer push-pull scheme for measuring buffer map gaps for all neighboring peers and a second per-peer push-pull method for measuring buffer map gaps for individual neighbors. have.

According to the first peer-specific push-pull scheme, the peer determines the delivery scheme (push or pull) for all of its neighbor peers.

According to the second peer-specific push-pull scheme, the peer determines the delivery scheme (push or pull) for each neighbor.

1 illustrates a per-chunk push-pull scheme according to an embodiment of the present invention.

Peer A 110, Peer B 130, and Peer C 150 are nodes in the network.

Peers 110, 130, and 150 each have one or more files. Peers 110, 130, and 150 share their files with each other over a P2P network.

The file contains one or more chunks.

Through sharing, the file possessed by peers 110, 130, or 150 may be a complete file or an incomplete file. A complete file is a file where all of the file has been downloaded to peer 110, 130 or 150. An incomplete file is a file where only a portion of the file has been downloaded to peer 110, 130, or 150.

Name the complete file corresponding to the incomplete file as the original file.

In FIG. 1, peer A 110, peer B 140 and peer C 170 each have a buffer map 120, 150 or 180 of a file shared by the P2P network.

These files all represent the same content (or application, document, etc.). Thus, when the file has been completely downloaded, the peers 110, 140, and 170 all have the same file.

The file consists of one or more chunks. In Fig. 1, the file consists of 10 chunks.

Buffer map 120 of peer A 110 represents the ten chunks and the state of each of the chunks. The leftmost block 130 (that is, the block corresponding to the frontmost part of the file) represents the first chunk, and the rightmost block 139 represents the tenth chunk.

The buffer map 150 of peer B 140 and the buffer map 180 of peer C 170 also represent states of the first through tenth chunks and the chunks, respectively. The blocks of the three buffer maps 120, 150, and 180 correspond to each other in order. For example, the first block 130 in buffer 120 of peer A 110, the first block 160 in buffer 150 of peer B 140 and the first in buffer 180 of peer C 170. The first block 190 all represents the first chunk.

Chunks are divided into downloaded and undownloaded chunks.

The downloaded chunk represents a chunk that has been completely downloaded to the peer and has the same contents as the chunk of the complete original file. Rare chunks and rare chunks to be described later are chunks that satisfy special conditions among downloaded chunks. In the following, the downloaded chunk is named "Cheer owned Chunk".

Missing chunks represent chunks that are not owned by a peer (or chunks that retain their initial values because they were not downloaded to the peer at all) and 2) chunks that are only partially downloaded to the peer. In the following, the missing chunk is named "Chunk not owned by peer".

For peer A 110, the first chunk, the fifth chunk, the eighth chunk and the tenth chunk are downloaded chunks, and the fourth chunk is the rare chunk of the downloaded chunks. For peer A 110, the second chunk, the third chunk, the sixth chunk, the seventh chunk, and the ninth chunk are chunks that have not been downloaded.

Peer A 110 has its own buffer map 120 and buffer maps 150 and 180 of other neighboring peers 140 and 170.

The rareness of each chunk is indicated at the top of the corresponding block in buffer map 120 of peer A 110.

The rareness of each of the chunks may be calculated based on the buffer maps 120, 150, and 180 of the peers 110, 140, and 170.

For example, for peer A 110, as indicated by the first block 130, the first chunk is an already downloaded chunk. In addition, the first chunk also has peer B 140 and peer C 170 already owning the first chunk. Thus, the number of occurrences of the first chunk is three, and the rareness of the first chunk is 1/3, that is, the inverse of the number of appearances (that is, about 0.33).

Also, as shown in the second blocks 131, 161, and 191 of peers 110, 140, and 170, peer A 110 does not own the second chunk, but peer B 140 and peer C do. 170 owns the second chunk. Therefore, the rarity of the second chunk is 1/2.

The rareness of the chunk may be a number greater than or equal to zero and less than or equal to one. The rarity of a chunk not owned by any peer in the network may be zero. The rareness of a chunk that is uniquely owned by a particular chunk in the network may be one.

As mentioned above, the rarity of the chunks indicates the distribution of the chunks and can be a criterion for determining the chunk delivery scheme (push or pull).

Chunks of high rarity can be targeted by push.

When a rare rare chunk (or a less distributed chunk) is transmitted by the push method, there is a low probability of collision due to the transmission. In addition, when the distribution of chunks having low distribution is increased through the transmission of the push method, peers that have not obtained the chunks may easily obtain the chunks through the pull method.

If a rare rare chunk is sent by a push, there is a high probability of wasting resources by collision. Therefore, the rarer chunks that are difficult to deliver to the push are delivered primarily through the pull method.

Based on the rareness of the chunks, a rarer chunk and a rare chunk can be determined.

High rare chunks may be chunks with an absolute or relatively high degree of rareness. The high rare chunk may be a chunk having a rareness above (or above) a particular first predetermined value. The rare rare chunk may be a chunk owned only by a particular peer (eg, a fourth chunk owned by peer A 120).

Rare chunks may be chunks with absolute or relatively low rarity. The rare chunk may be a chunk whose rareness is below (or below) a particular second predetermined value. The rare chunk may be a chunk not owned only by a particular peer (eg, a second chunk not owned only by peer A 110).

The rare chunk may be a chunk close to the regeneration point. If the file is currently being played by a particular peer 110, 140, or 180, the chunk close to the playback point of the file (that is, the portion of the file being played) is classified as a rare chunk and is quickly accessed by the particular peer. Need to be forwarded to (110, 140 or 180).

Thus, the rare chunk can be determined based on the rareness of the chunk and proximity to the playback point of the file, as described above.

Peer A 110 may deliver its own rare chunk (eg, fourth chunk) to neighbor peer 140 or 170 in a push manner. Due to the push-type transmission, the probability that the chunk is transmitted in duplicate is reduced.

Peer A 110 may request a neighboring peer 140 or 170 for a rare chunk (eg, a second chunk or a seventh chunk) that it does not own (ie, has not been downloaded to it). The requested peer 140 or 170 forwards the requested chunk to peer A 110, and peer A 110 obtains the chunk requested by it.

When the time point at which peer A 110 delivers a particular chunk to the neighbor peer 140 or 170 as a push, and the time point at which neighbor peer 140 or 170 requests the specific chunk to peer A 110, the There may be a problem that certain chunks are duplicated.

To solve this problem, peer A 110 keeps information on which other peer 140 or 170 the chunk sent to the push or pool has been sent for a period of time, so that individual chunks are delivered to a peer only up to once. It can be done.

This information may be maintained by setting a bit corresponding to the particular chunk in the buffer map 150 or 180 of the neighboring peer 140 or 170 with peer A 110.

2 illustrates a first peer-to-peer push-pull scheme according to an embodiment of the present invention.

The first per-peer push-pull scheme selects one of push and pool as the transmission scheme for a particular peer based on the buffer map gap.

In order for a peer to use the buffer map gap as an optimal indicator for selecting push and pool, the buffer map gap must be measured for chunks owned by the peer.

For example, according to the buffer map 220 of peer A 210, peer A 210 is a first chunk, a third chunk, a fourth chunk, a sixth chunk, a ninth chunk, a tenth chunk, a fourteenth chunk, and the like. Has a fifteenth chunk. Therefore, only the chunks described above are used as chunks for measuring the buffer map gap.

Equation 1 described above also includes chunks not owned by the peer itself that calculates the buffer map gap, in the buffer map calculation. Therefore, the equation 1 is not suitable for the buffer map calculation in the present embodiment.

In the present embodiment, the buffer map gap may be defined according to Equation 2 below.

Here, i represents a peer for calculating a buffer map gap, and j represents jth neighbor peers of i. m represents the number of neighbors of peer i. DC _i (j) represents the number of chunks not owned by peer j among the chunks owned by peer i.

For example, among the chunks owned by peer A 210 (i.e. i = 1), chunks not owned by peer B (since = 1 since peer B is the first neighbor) are the sixth chunk ninth chunk and the first chunk. 10 chunks. Therefore, DC ₁ (1) is three.

In FIG. 1, for each of peers B to E, DC ₁ (2) to DC ₁ (5) are shown.

In addition, the buffer map gap is (3 + 5 + 4 + 5) / 4 = 4.125.

Peer A 210 is based on the information in its buffer map 220 and the buffer maps 230, 240, 250, and 260 of neighboring peers (ie, using Equation 2). And determine a delivery method (push or pull) for all neighbor peers based on the calculated buffer map gap 270.

Because the buffer map gap indicates how many chunks each neighbor owns, the buffer map gap indicates that peer A 210 is not able to push or pull between neighbors (i.e., neighbor peers B to neighbor peer E). The method can be used as an indicator to choose whether or not to carry out data transfer should be efficient.

Peer A 210 selects one of a push method and a pull method according to the measured buffer map gap, and operates according to the selected method. For example, if the value of the buffer map gap is greater than or equal to a predefined value, peer A 210 may operate in a pull manner. If the value of the buffer map gap does not reach a predefined value, the peer 210 may operate in a push manner.

The predefined value may be determined based on the size of the buffer map and the number of neighbors.

A high calculated buffer map gap means that there is relatively little duplication between chunks owned by peers. In this case, the collision rate is low even though the chunk is delivered to the neighbors by the push.

On the other hand, a low calculated buffer map gap means that many of the chunks owned by the peers overlap. In this case, it is more efficient to pass the chunk by the pool rather than the push that is more likely to crash.

In addition, when a chunk is delivered to neighbors by push, peer A 210 may preferentially deliver a high rare chunk to a neighbor that does not own the chunk, as used in the per-chunk push-pull. .

A rareness of the chunks owned by peer A 210 is shown. The ninth and tenth chunks with the highest rareness among the chunks may be selected as the chunks to be preferentially delivered by the push. In addition, the fourteenth chunk already owned by all neighboring peers may be excluded from transmission.

The buffer maps 220, 230, 240, 250, and 260 described above may be a playback buffer for playing a file of each peer.

3 illustrates a second peer-to-peer push-pull scheme according to an embodiment of the present invention.

According to the buffer map 320 of peer A 310, peer A 310 is the second chunk, the fourth chunk, the sixth chunk, the seventh chunk, the eighth chunk, the eleventh chunk, the fourteenth chunk, and the sixteenth chunk. Has a chunk.

Peer A 310 selects one of a push method and a pull method for each of the neighboring peers by measuring a buffer map gap for each of the neighboring peers, and operates according to the selected method.

Therefore, in the present embodiment, the buffer map gap may be defined according to Equation 3 below instead of Equation 2 described above.

Here, i represents a peer for calculating a buffer map gap, and j represents a j-th neighbor peer of i. DC _i (j) represents the number of chunks not owned by peer j among the chunks owned by peer i.

For example, among the chunks owned by peer A 310 (i.e. i = 1), chunks not owned by peer B 330 (since peer = 330 is the first neighbor, j = 1) are the eighth. It is chunk. Therefore, DC ₁ (1) is 0.5. Of the chunks owned by peer A 310 (i.e. i = 1), the chunks not owned by peer C 350 (since j = 2) are the second chunk, Sixth chunk, eighth chunk, eleventh chunk, and sixteenth chunk. Therefore, DC ₁ (2) is 2.5.

Since the buffer map gap is measured for each neighbor 330 and 350, peer A 310 selects one of push and pool for each neighbor 330 and 350, so that neighbor 330 or 350 depends on the selected method. Send and receive chunks.

Peer A 310 may deliver a chunk to a neighbor peer C 350 having a high buffer map gap by using a push method, and may transmit a pull request message to a neighbor peer B 330 having a low buffer map gap.

The push and pull method may be selected based on a predetermined value. That is, peer A 310 may use a push method to deliver a chunk to neighboring peers whose buffer map gap is greater than or equal to a predetermined value, and pull requests to neighboring peers whose buffer map gap is smaller than the predetermined value. You can pass a message.

In addition, the peer 310 can basically use the pool for all neighboring peers 330 and 350 as a transmission scheme. The peer 310 measures the buffer map gap with respect to a specific neighbor peer 330 or 350, and when the measured buffer map gap becomes more than a predetermined value, the peer 310 converts the transmission method with the neighbor peer into a push method. Can be.

In addition, when a file is played at peer A 310, peer A 310 may request neighboring peers that have selected the pull method to close chunks that are close to the playback point but have not yet been obtained.

Peer A 310 may select a chunk to be preferentially delivered to neighboring peers whose push method is selected based on the rarity of the chunk described above.

In addition, the other peers 330 and 350 may also measure the buffer map gap with peer A 310 to select the delivery method of the chunk according to the measurement result. Thus, two neighboring peers can send and receive chunks using different methods.

If only one of the two neighboring peers has multiple chunks, only one of the peers can use the push to pass the chunks to the other peer.

The buffer maps 320, 340, and 360 described above may be a playback buffer for playing a file of each of the peers 310, 330, and 350.

4 is a flowchart of a method in which a node in a P2P network shares a file using a per-chunk push-pull scheme according to an embodiment of the present invention.

The file contains one or more chunks.

The file may be a file being played by the node.

In step S410, the buffer map information is received from neighbor nodes.

In step S420, the rareness of each of the one or more chunks included in the file is calculated based on the received buffer map information of the neighbor nodes.

In step S430, a transmission and reception scheme of each of one or more selected chunks of one or more chunks is determined based on the calculated rareness.

The transmission and reception method is the above-described push method or pull method.

A rareness of the one or more chunks is greater than or equal to the first predefined value, and the chunk owned by the node may be selected as the high rare chunk. Also, a chunk owned only by a node of one or more chunks may be selected as the rare chunked.

Chunks of one or more chunks that are less than the first predefined value, owned by one or more of the neighbor nodes, and not owned by the node, may be selected as rare chunks. Also, a chunk not owned only by a node of one or more chunks may be selected as a rare chunk. In addition, a particular chunk of one or more chunks may be selected as a rare chunk based on the degree of rarity and the distance to the playback point of the file.

In step S440, each of the selected one or more chunks is transmitted and received according to the determined transmission and reception scheme.

The high rare chunk may be transmitted to a chunk not including the high rare chunk among neighboring nodes.

A node including a rare chunk of neighboring nodes may be requested to transmit the rare chunk, and the rare chunk may be received from the neighboring node.

Technical content according to an embodiment of the present invention described above with reference to FIGS. 1 to 3 may be applied to the present embodiment as it is. Therefore, more detailed description will be omitted below.

5 is a structural diagram of a node using a chunk-by-chunk push-pull method according to an embodiment of the present invention.

The node 500 includes a rareness calculator 510, a transmission / reception scheme determiner 520, and a transceiver 530.

The rareness calculator 510 calculates the rareness of each of the one or more chunks included in the file based on the buffer map information of the neighbor nodes.

The transmission / reception scheme determination unit 520 determines a transmission / reception scheme for each of one or more selected chunks among the one or more chunks based on the calculated rareness.

The transmission and reception method is a push method or a pull method.

The transceiver 530 transmits and receives each of the selected one or more chunks according to the determined transmission and reception scheme.

The transmission / reception scheme determining unit 520 may select a chunk owned by the node as a rare rare chunk having a rareness of one or more chunks or more, and the transceiver 530 may select the rare rare chunk as a neighbor. The node may transmit to a chunk not including the rare chunk of nodes.

The transmission / reception scheme determining unit 520 may select as a rare chunk a rareness among one or more chunks that is less than the first predefined value, and is owned by one or more nodes among neighboring nodes and not owned by the node. The transceiver 530 may request a node including a rare chunk among neighboring nodes to transmit the rare chunk, and receive the rare chunk from the neighbor node.

6 is a flowchart of a method in which a node in a P2P network shares a file using a per-chunk push-pull scheme according to an embodiment of the present invention.

The file contains one or more chunks.

The file may be a file being played by the node.

In step S610, the buffer map information is received from neighboring nodes.

In operation S620, the buffer map gap is calculated based on the received buffer map information of the neighbor nodes and the buffer map information of the node.

In step S630, a method of transmitting and receiving one or more selected chunks of one or more chunks is determined based on the calculated buffer map gap.

The transmission and reception method is the above-described push method or pull method.

In step S640, each of the selected one or more chunks is transmitted and received according to the determined transmission and reception scheme.

First, the case where the above-described first chunk-by-push push method is used will be described in detail.

In operation S620, the buffer map gap for all neighboring nodes may be calculated based on the buffer maps of all the neighbor nodes and the buffer map of the node.

In step S630, the pull scheme may be determined as a transmission / reception scheme of one or more selected chunks when the calculated buffer map gap is greater than or equal to a predefined value, and the push scheme is one or more selected chunks when the buffer map gap is less than a predefined value. May be determined as a transmission / reception scheme of these.

In addition, based on the buffer map information of neighboring nodes, the rareness of each of the one or more chunks included in the file may be calculated, and the rareness of the one or more chunks is greater than or equal to the first predefined value and is owned by the node. The chunk may be determined to be the selected chunk to send in the pull manner.

Next, a case where the above-described second chunk-by-push push method is used will be described in detail.

In operation S620, the buffer map gap for each of the neighbor nodes may be calculated based on the buffer map of each of the neighbor nodes and the buffer map of the node.

In operation S630, a method of transmitting and receiving one or more selected chunks to each of the neighbor nodes may be determined based on a buffer map gap of each of the neighbor nodes.

In addition, a pooling scheme may be determined as a transmission / reception scheme of one or more selected chunks for a neighbor node whose buffer map gap is greater than or equal to a predefined value among neighboring nodes, and a neighbor node whose buffer map gap is less than a predefined value among neighboring nodes. The push method may be determined as a transmit / receive method of one or more selected chunks.

7 is a structural diagram of a node using a chunk-by-chunk push-pull method according to an embodiment of the present invention.

The node 700 includes a buffer map gap calculator 710, a transmission / reception scheme determiner 720, and a transceiver 730.

The node 700 may include a rareness calculator 740.

The buffer map gap calculator 710 calculates a buffer map gap based on the buffer map information of the neighbor nodes and the buffer map information of the node.

The transmission / reception scheme determination unit 720 determines a transmission / reception scheme of one or more selected chunks of the one or more chunks based on the calculated buffer map gap.

The transmission and reception method is a push method or a pull method.

The transceiver 730 transmits and receives one or more selected chunks according to the determined transmission and reception scheme.

First, the case where the above-described first chunk-by-push push method is used will be described in detail.

The buffer map gap calculator 710 may calculate the buffer map gap for all of the neighbor nodes based on the buffer maps of all the neighbor nodes and the buffer map of the node, and the transmission / reception scheme determination unit 720 determines the buffer map gap. If the value is greater than or equal to the first predefined value, the pull method may be determined as a transmission / reception method of one or more selected chunks, and when the buffer map gap is less than the first predefined value, the push method may be determined as a transmission / reception method of one or more selected chunks. .

The rareness calculator 740 may calculate the rareness of each of the one or more chunks included in the phase file based on the buffer map information of the neighbor nodes, and the transmission / reception scheme determiner 720 may determine the rareness of the one or more chunks. Is greater than or equal to the second predefined value, and the chunk owned by the node may be determined as the selected chunk to be transmitted in a pull manner.

Next, a case where the above-described second chunk-by-push push method is used will be described in detail.

The buffer map gap calculator 710 may calculate the buffer map gap for each of the neighbor nodes based on the buffer map of each of the neighbor nodes and the buffer map of the node, and the transmission / reception scheme determination unit 720 determines the neighbor nodes. Based on each buffer map gap, a method of transmitting and receiving one or more selected chunks to each of the neighbor nodes may be determined.

The transmission / reception scheme determination unit 720 may determine a pull scheme as a transmission / reception scheme of one or more selected chunks among neighboring nodes whose buffer map gap is greater than or equal to a first predefined value. The push method may be determined as a transmission / reception scheme of one or more selected chunks for a neighbor node that is less than the first predefined value.

The performance of the three push-pull schemes proposed below is analyzed.

The analysis below is by event-driven simulation on a Java-based PeerSim simulator. For performance comparison with the selective push-pull method, the typical mesh-based push method DP / LU and general random pull method are implemented. For convenience, the chunk-by-chunk push-pull is the chunk-star, the first peer-star push-pull is the first peer-star, the second peer-star push-pull is the second peer-by-pattern in the manner mentioned in the present invention. Outline.

Simulation parameters are shown in Table 1 below.

Parameters value Number of nodes 2500 Chunk size 14 KB Packet loss rate 2% Streaming rate 336 kbps Number of neighbors 15 Window size 30 seconds (90 chunks) Round spacing 500 msec Start-up delay Up to 30 seconds Simulation time 12.5 minutes

In the following simulation, the objective facts affecting the system performance are reflected as close as possible to the real world user pattern as shown in Table 1 above.

 The node-to-node latency matrix (2500X2500) with an average latency of 79 ms measured on the Internet was used to reflect the real-time node-to-node latency.

Since the number of nodes must be at least as large as the size of the delay matrix, it is assigned around 2500. Since the delay matrix is reflected in TCP segment units, it is assumed that the TCP segment has the maximum payload (1460 bytes), and 14KB, which is 10 times this value, is determined as the chunk size to facilitate calculation.

The rate of packet loss is set at 2%.

The streaming rate was specified at 336 kbps so that the number of chunks required per second was three.

The number of neighbors in the node was set to 15, and the size of the downloading window was set to 30 seconds (90 chunks).

The round period is set to 500 ms to reflect the average delay time of the delay matrix.

Table 2 below shows the basic bandwidth distribution.

Upload bandwidth Download bandwidth Fraction of nodes ( fraction ) 128 (kbps) 768 (kbps) 0.2 384 1536 0.4 1024 3072 0.15 4096 6144 0.15

In the following simulations, a Poisson distribution, a Log-normal distribution, and a Pareto distribution were used to model dynamic behavior such as peer participation and duration.

Peers' participation method follows the Posasong process and reflects the distribution of the number of clients in the actual system.

On the other hand, since the system lifetime of the peers follows a heavy-tailed distribution, about 90% of the peers follow the log-normal distribution, and 10% of the peers survive the Pareto distribution.

The μ and σ parameters of the log-normal distribution are 0 and 1.6, respectively, the χm and α parameters of the Pareto distribution are 1 and 0.9, and the λ parameter of the Poisson distribution is 38.

If the downloading window does not download enough chunks, it will be difficult to deliver enough data to the media player to play the video.

At this time, the following simulation does not stop the media player and skips the missing frame.

Finally, since the peer-simulator does not provide a network topology of a full bidirectional connection, the peer-simulator can be extended / modified to allow better bi-directional connectivity.

8 illustrates an effective download ratio and a total download ratio according to an embodiment of the present invention.

The effective download rate refers to the rate at which data is successfully played at the peer without any problems (without stopping or skipping playback), also referred to as playout continuity. The effective download rate is determined by the ratio of the amount of chunks downloaded and the streaming rate of the system, excluding duplicate transmissions per peer.

The total download rate is an indicator for determining how much data is transmitted in the entire system, including redundant transmission, and is defined as the ratio of the average data download amount and the streaming rate per peer.

Table 3 below shows the effective download ratio, which is a representative index for determining a user quality of experience (QoE) of each P2P streaming service, for each method.

DP / LU Random pool Chunk-Stars First peer-star First Peer-Specific Option Second peer-star Effectiveness
Download rate
0.79
0.91
1.05
0.97
1.02
0.99

DP / LU has the lowest performance of 0.79 due to redundant transmission during operation.

The random pull method has an effective download rate of about 0.91.

All of the above schemes show good performance, but the first peer-by-peer scheme does not show good performance because it operates only in one of the push scheme and the pull scheme. In particular, since the push method always selects chunks and peers by itself, a large number of redundant transmissions may occur even when the buffer map gap is high. Because all the upload bandwidth is used by push method, even if it is delivered according to the rareness, chunks with low rareness are also delivered.

In order to solve this problem, it is desirable to not use all of the upload bandwidth for the pool even in the process of using the pool, but to leave some of them for the purpose of processing the push request.

Therefore, selecting within push-pools and pools improves performance rather than selecting within pushes and pools, as is traditional. In order to distinguish from the existing first peer-by-peer method, a method of selecting one of the push-pull and the pool is called a first peer-per-option (or a first peer-per-push push-pull option) method.

Looking at Table 1, it can be seen that the first peer-by-option method performs better than the first peer-by-peer method. Since the first peer-by-option method has an effective download rate similar to that of the chunk-by-choice method, it is determined that the analysis is more meaningful. Thus, in the following example of the present invention, the first peer-by-peer method is used instead of the first peer-by-peer method.

The first graph 810 and the second graph 820 show an effective download rate and a total download rate, respectively. Basically, the random full l method has a ratio of 0.9 on average and shows slightly better performance than DP / LU showing 0.8 performance.

The effective download rates of the three selective push-pull schemes, the chunk-specific, the first peer-optional, and the second peer-specific, are 1.05, 1.02, and 0.99, respectively, compared to random pool and DP / LU. The performance improved by about 15%.

This demonstrates that timely use of pushes and pulls perform better than simply using only pulls or pushes.

All three methods show similar performance, but the best method is to select push and pull by measuring the rarity of each chunk.

It is the selection index of push and pool, which means that the rarity per chunk is better than the buffer map gap, and that the buffer map gap measurement for the whole neighborhood is better as an indicator of push and pool selection than the measurement for individual neighbors. Can be.

The second graph 820 shows the data transmission amount of the entire system including redundant transmission.

The random pull scheme in which duplicate transmission rarely occurs is located at the bottom. The Chunk-by-Peer, First Peer-to-Peer, and Second Peer-to-Peer have a similar amount of total download rate, and the DP / LU, which operates only in the push mode, is located at the top.

The total download rate of the DP / LU shows an average performance of 2.0, compared with the effective download rate of less than 1.0.

On the other hand, in contrast to DP / LU, the total download rate of the random pull method is similar to the effective download rate, so it can be expected that there is almost no duplicate transmission.

Chunk-by-Chef, First Peer-by-Option, and Second Peer-by-Pass have an average total download rate of about 1.5, with 1.7 times the random pull method and 0.8 times the DP / LU method. I can see it.

Since the total download rate of the second graph 820 is the total transmission amount including duplication, it can also be viewed as the actual usage of upload bandwidth. The performance improvement of the selective push-pull scheme described above is also attributable to the small control overhead ratio and the small surplus ratio, which will be described later, but may be attributed to the increase in upload bandwidth usage by using the push scheme.

9 shows a miss ratio according to an embodiment of the present invention.

In a P2P streaming service, chunks must arrive before their playback time point for smooth playback.

Lost chunks cause the video to stop playing or skip. Thus, the number of chunks lost is an important criterion for evaluating the performance of the system.

The miss rate refers to the percentage of chunks lost and is defined as the ratio of the average number of chunks lost per peer and the streaming rate.

The first graph 910 represents the miss rate of each scheme. The DP / LU method and the random pull method show the miss rates of 0.14 and 0.11, respectively, and the proposed methods show about 0.5 to 0.6 performance and reduce the miss rate by about 1/2 compared to the conventional methods. It can be seen that.

FIG. 10 illustrates a diffusion rate and a diffusion delay according to an embodiment of the present invention. FIG.

The divergence rate is an indicator of how many chunks are delivered to a chunk after a certain time, and is defined as the number of peers that own any chunk after a certain time.

The divergence delay is an indicator of how quickly a chunk created by the server is delivered to peers, and is defined as the time it takes for a certain number of peers to own the chunk.

The first graph 1010 represents the divergence rate and divergence which are performance indicators of the mesh-based streaming service. As mentioned above, the divergence rate represents the number of peers whose chunks have been created from the server and delivered over time, and the divergence delay represents the time it took for the peer to own the chunk.

However, this value is based on the static situation where there is no departure and participation of nodes. Since the embodiments of the present invention assume a dynamic situation that carefully reflects the behavior pattern of the nodes using the live streaming service in the real world, the result is somewhat different from the existing results.

However, this difference is only a low value of convergence of the divergence ratio and the divergence delay curve, and did not occur in the form of the divergence ratio and the divergence delay curve.

For approximately 100 seconds of measurement time, the chunk-by-chunk method, the first peer-to-peer option, and the second peer-to-peer method converge at about 50% of the value, while the DP / LU and random pool are further down. Converge.

As described above, the transmission using the push method has a faster propagation rate than the transmission using the pull method, and thus shows an improved spread delay.

In the first graph 1010, comparing the time it takes to reach a diffusion rate of 30% (diffusion delay), the schemes proposed by embodiments of the present invention are about 1/3 of the random pool, DP / LU. It can be seen that the spread delay is about 1/2.

Better performance than random pools is because push is more advantageous than propagation in terms of propagation speed, and better performance than DP / LU is because it uses push while minimizing redundant transmissions based on chunked rareness or buffer map gaps. to be.

It can be seen that the graph is bent at around 60 seconds for the chunk-by-first method and the first peer-to-option method and around 30 seconds for the second peer-star method. This is the point where the chunk delivery, which was mostly done through the push method, changed to the pull method.

In the case of the second peer-to-peer scheme, the transition point appears earlier than the previous two schemes, and in the second peer-to-peer scheme, there is less propagation using push and thus less collision due to duplicate transmission. Can be inferred.

11 illustrates an overhead ratio according to an embodiment of the present invention.

Peers exchange their neighbors with a list of neighbors, a buffer map, and a pull request message. Except for chunk exchange, the information exchanged with the neighbor is called a control message ratio, and is defined as the ratio of the transmission amount of the entire system excluding the amount of transmission and duplication. In addition, the ratio of the transmission amount used by the collision occurrence in the push method and the transmission amount of the entire system is defined as a redundancy ratio. The total control message overhead and surplus rate are defined as total overhead ratio.

The first graph 1110, the second graph 1120, and the third graph 1130 represent overheads of transmission of duplicate transmissions and control messages. Third graph 1130 shows the total overhead ratio.

On the average, a random pool having a value of about 0.05 has the least overhead, an average chunk-by-chance method of 0.36, a first peer-to-peer option method of 0.35, and a second peer-to-peer method of 0.30. DP / LU is about 0.60 overhead, with the largest total overhead ratio.

The total overhead ratio is almost similar to the chunk surplus ratio of the first graph 1110. This means that redundant transmission by push takes up most of the overall overhead.

 The surplus ratio of DP / LU is about 0.59. In this method, it has a value of about 0.3, which is 60% of DP / LU.

Among the three methods according to the embodiments of the present invention, the chunk-by-method method has the highest surplus ratio of about 0.36, and the first peer-by-option method that uses the push map appropriately by utilizing the buffer map gap is 0.35. Then occupies. Finally, the second peer-to-peer scheme has a value of 0.30 because the number of chunks delivered to the push is less than other schemes, as well as the push scheme is most appropriately used.

The second graph 1120 represents the control message overhead, which is the amount of control messages for the total downloaded amount. For more accurate comparison, the second graph 1120 is measured by dividing the total amount of control messages by the total amount of downloads excluding duplicate chunks.

In the second graph 1120, the random pool has a value of about 0.04, while the three selective push-pull schemes have a value of about 0.02 with about 50% reduction in overhead.

In practice, all four schemes have similar values in the amount of control messages, but the random-pull scheme is much smaller in the total download amount, so the control message occupies a higher percentage than the selective push-pull scheme.

12 illustrates a push fraction according to an example of the present invention.

Since the optional push-pull scheme described above can use push and pull simultaneously or alternately, it is shown how well the push was used without duplication by comparing the ratio and surplus ratio of the chunk delivered to the push within the total delivered chunk. Information for judging can be provided.

The first graph 1210 shows the proportion of chunks delivered to the push and the proportion of redundant transmission.

In the case of the second peer-to-peer scheme, the weight of delivery by push is smaller than the other schemes, and the duplicate transmission rate is the smallest. This indicates that the method based on buffer map gap measurement between two peers is highly efficient in delivering chunks by push.

As a result of the above simulations, by using the selective push-pull method according to the embodiments of the present invention, the surplus ratio is reduced to 1/2, and the control message overhead ratio is reduced by about 50%. In addition, since the bandwidth usage is increased by twice, the performance is improved by about 15% in the effective download rate.

Method according to an embodiment of the present invention is implemented in the form of program instructions that can be executed by various computer means may be recorded on a computer readable medium. The computer readable medium may include program instructions, data files, data structures, etc. alone or in combination. The program instructions recorded on the medium may be those specially designed and constructed for the present invention or may be available to those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tape, optical media such as CD-ROMs, DVDs, and magnetic disks, such as floppy disks. Magneto-optical media, and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, and the like. Examples of program instructions include not only machine code generated by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

As described above, the present invention has been described by way of limited embodiments and drawings, but the present invention is not limited to the above embodiments, and those skilled in the art to which the present invention pertains various modifications and variations from such descriptions. This is possible.

Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the claims.

500: node
510: rareness calculator
520: transmission and reception method determination unit
530: transceiver

Claims (26)

A method in which nodes in a peer-to-peer network share files with neighboring nodes,
Calculating a rareness of each of the one or more chunks included in the file based on buffer map information of the neighbor nodes;
Determining a transmission and reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness; And
Transmitting and receiving each of the selected one or more chunks according to the determined transmission / reception scheme
Wherein the buffer map information includes information about whether the neighbor node owns each of the one or more chunks, and the rareness is between the node and the neighbor nodes within the P2P network. And how each of the chunks is spread, and the transmission / reception scheme is a push scheme or a pull scheme. The method of claim 1,
Receiving the buffer map information from the neighbor nodes
Further comprising, file sharing method. The method of claim 1,
And wherein said rareness is an inverse of the number of appearances of each of said one or more chunks in said node and said neighboring nodes. The method of claim 1,
Determining a transmission and reception method of each of one or more selected chunks of the one or more chunks based on the rareness,
Selecting the first chunk as a high rare chunk when the rareness of a first chunk of the one or more chunks is greater than or equal to a first predefined value and the node owns the first chunk.
Including,
Transmitting and receiving each of the selected one or more chunks according to the determined transmission / reception scheme
Transmitting the high rare chunk to a node among the neighboring nodes that does not include the high rare chunk.
Including, file sharing method. The method of claim 1,
Determining a transmission and reception method of each of one or more selected chunks of the one or more chunks based on the rareness,
If the node owns a first chunk of the one or more chunks and the neighboring nodes do not own the first chunk, selecting the first chunk as a high rare chunk.
Including,
Transmitting and receiving each of the selected one or more chunks according to the determined transmission / reception scheme
Transmitting the rare rare chunk to one or more of the neighboring nodes.
Including, file sharing method. The method of claim 1,
Determining a transmission and reception method of each of one or more selected chunks of the one or more chunks based on the rareness,
The rareness of a second one of the one or more chunks is less than a first predefined value, one or more of the neighboring nodes own the second chunk, and the node does not own the second chunk. If not, selecting the second chunk as a rare chunk
Including,
Transmitting and receiving each of the selected one or more chunks according to the determined transmission and reception scheme,
Requesting transmission of the rare chunk to a node including the rare chunk of the neighbor nodes; And
Receiving the rare chunk from the neighbor node
Including, file sharing method. The method of claim 1,
Determining a transmission and reception method of each of one or more selected chunks of the one or more chunks based on the rareness,
If the node does not own a second chunk of the one or more chunks, and the neighbor nodes all own the second chunk, selecting the second chunk as a rare chunk
Including,
Transmitting and receiving each of the selected one or more chunks according to the determined transmission and reception scheme,
Requesting transmission of the rare chunk to one or more of the neighboring nodes; And
Receiving the rare chunk from the one or more nodes for which the transmission of the rare chunk has been requested
Including, file sharing method. The method of claim 1,
The file is a file being played by the node,
Determining a transmission and reception method of each of one or more selected chunks of the one or more chunks based on the rareness,
Selecting a particular one of the one or more chunks as a rare chunk based on the rareness and the distance to the playback point of the file
Including,
Transmitting and receiving each of the selected one or more chunks according to the determined transmission and reception scheme,
Requesting transmission of the rare chunk to one or more of the neighboring nodes; And
Receiving the rare chunk from the one or more nodes for which the transmission of the rare chunk has been requested
Including, file sharing method. In a node that shares files with neighboring nodes in a peer-to-peer (P2P) network,
A rareness calculator configured to calculate a rareness of each of the one or more chunks included in the file based on the buffer map information of the neighbor nodes;
A transmission / reception scheme determination unit determining a transmission / reception scheme of each of one or more selected chunks of the one or more chunks based on the rareness; And
Transmitting and receiving unit for transmitting and receiving each of the selected one or more chunks according to the determined transmission and reception scheme
Wherein the buffer map information includes information about whether the neighbor node owns each of the one or more chunks, and the rareness is between the node and the neighbor nodes within the P2P network. Each of the chunks is indicative of spread, and the transmission / reception scheme is a push scheme or a pull scheme. 10. The method of claim 9,
And said rareness is an inverse of the number of appearances of each of said one or more chunks in said node and said neighboring nodes. 10. The method of claim 9,
The transmission / reception scheme determination unit selects the first chunk as a high rare chunk when the rareness of the first chunk of the one or more chunks is equal to or greater than a first predefined value and the node owns the first chunk. ,
The transceiver unit transmits the high rare chunk to a node that does not include the high rare chunk among the neighboring nodes. 10. The method of claim 9,
The transmission / reception scheme determining unit may be configured that the rareness of the second chunk of the one or more chunks is less than a first predefined value, at least one node of the neighboring nodes owns the second chunk, and the node is configured as the first chunk. 2 if the chunk is not owned, select the second chunk as a rare chunk,
The transceiver unit requests a node including the rare chunk of the neighbor nodes to transmit the rare chunk, and receives the rare chunk from the neighbor node. A method in which nodes in a peer-to-peer network share files with neighboring nodes,
Calculating a buffer map gap based on buffer map information of the neighbor nodes and buffer map information of the node;
Determining a transmission / reception scheme of one or more selected chunks of the one or more chunks based on the buffer map gap; And
Transmitting / receiving the selected one or more chunks according to the determined transmission / reception scheme
Wherein the buffer map information includes information about whether the neighbor node owns each of the one or more chunks, and the buffer map gap is between buffer map information of the neighbor nodes and buffer map information of the node. Means the gap, the transmission and reception method is a file sharing method, a push method or a pull method. The method of claim 13,
Receiving the buffer map information from the neighbor nodes
Further comprising, file sharing method. The method of claim 13,
Computing a buffer map gap based on the buffer map information of the neighbor nodes and the buffer map information of the node,
Calculating the buffer map gap for all of the neighbor nodes based on the buffer maps of all the neighbor nodes and the buffer map of the node.
Including,
The method of transmitting and receiving the one or more selected chunks of the one or more chunks based on the buffer map gap may include:
Determining a pull scheme as a transmission / reception scheme of the one or more selected chunks when the buffer map gap is equal to or greater than a first predefined value; And
Determining a push method as a transmission / reception method of the one or more selected chunks when the buffer map gap is less than the first predefined value.
Including, file sharing method. 16. The method of claim 15,
The buffer map gap for all of the neighbor nodes is determined based on Equation 1 below.
[Equation 1]

Where DC _i (j) is the number of chunks owned by the node of the one or more chunks and not owned by the j th neighbor node of the neighboring nodes, and m is the number of neighbor nodes. 16. The method of claim 15,
And the first predefined value is determined based on a size of the node's buffer map and the number of neighboring nodes. 16. The method of claim 15,
When the buffer map gap is greater than or equal to a first predefined value, determining a pull method as a transmission / reception method of the one or more selected chunks,
Calculating a rareness of each of the one or more chunks included in the file based on buffer map information of the neighbor nodes; And
Determining the rareness of the first chunk of the one or more chunks is greater than or equal to a second predefined value, and if the node owns the first chunk, transferring the first chunk to the selected chunk in a pull manner;
And wherein the rarity indicates a degree to which each of the one or more chunks has spread between the node and the neighboring nodes within the P2P network. The method of claim 13,
Computing a buffer map gap based on the buffer map information of the neighbor nodes and the buffer map information of the node,
Calculating the buffer map gap for each of the neighbor nodes based on the buffer map of each of the neighbor nodes and the buffer map of the node.
Including,
The method of transmitting and receiving the one or more selected chunks of the one or more chunks based on the buffer map gap may include:
Determining a transmission / reception scheme of the one or more selected chunks to each of the neighbor nodes based on the buffer map gap of each of the neighbor nodes.
Including, file sharing method. 20. The method of claim 19,
The method of transmitting and receiving the one or more selected chunks to each of the neighbor nodes based on the buffer map gap of each of the neighbor nodes may include:
Determining a pull scheme for the first neighbor node as a transmission / reception scheme of the one or more selected chunks when the buffer map gap of the first neighbor node of the neighbor nodes is equal to or greater than a third predefined value; And
Determining a push method as the transmission / reception scheme of the one or more selected chunks for the second neighbor node when the buffer map gap of the second neighbor node of the neighbor nodes is less than the third predefined value.
Including, file sharing method. 20. The method of claim 19,
The buffer map gap for each of the neighbor nodes is determined based on Equation 2 below.
&Quot; (2) "

Where DC _i (j) is the number of chunks owned by the node of the one or more chunks and not owned by the j th neighbor node of the neighboring nodes. In a node in a peer-to-peer (P2P) network that shares files with neighboring nodes,
A buffer map gap calculator configured to calculate a buffer map gap based on the buffer map information of the neighbor nodes and the buffer map information of the node;
A transmission / reception scheme determination unit determining a transmission / reception scheme of one or more selected chunks of the one or more chunks based on the buffer map gap; And
Transmitting and receiving unit for transmitting and receiving the selected one or more chunks according to the determined transmission and reception scheme
Wherein the buffer map information includes information about whether the neighbor node owns each of the one or more chunks, and the buffer map gap is between buffer map information of the neighbor nodes and buffer map information of the node. Means a gap, wherein the transmission and reception method is a push method or a pull method. The method of claim 22,
The buffer map gap calculator calculates the buffer map gap for all of the neighbor nodes based on the buffer maps of all the neighbor nodes and the buffer map of the node.
The transmission / reception scheme determination unit determines a pull scheme as the transmission / reception scheme of the one or more selected chunks when the buffer map gap is greater than or equal to a first predefined value, and selects a push scheme when the buffer map gap is less than the first predefined value. A network node that determines the transmission and reception of the one or more selected chunks 24. The method of claim 23,
A rareness calculator for calculating a rareness of each of the one or more chunks included in the file based on the buffer map information of the neighbor nodes.
Further comprising:
The transmission / reception scheme determining unit is configured to transmit the first chunk in a pull manner when the rareness of the first chunk of the one or more chunks is equal to or greater than a second predefined value and the node owns the first chunk. Decided in chunks.
And said rareness represents the extent to which each of said one or more chunks has spread between said node and said neighboring nodes within said P2P network. The method of claim 22,
The buffer map gap calculator calculates the buffer map gap for each of the neighbor nodes based on the buffer map of each of the neighbor nodes and the buffer map of the node,
The transmission / reception scheme determination unit determines a transmission / reception scheme of the one or more selected chunks to each of the neighbor nodes based on the buffer map gap of each of the neighbor nodes. 26. The method of claim 25,
The transmission / reception scheme determination unit determines a pull scheme as the transmission / reception scheme of the one or more selected chunks for the first neighbor node when the buffer map gap of the first neighbor node among the neighbor nodes is equal to or greater than a third predefined value, And determine a push method for the second neighbor node as a transmission / reception scheme of the one or more selected chunks when the buffer map gap of a second neighbor node of the neighbor nodes is less than the third predefined value.

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