JP5724139B2 - P2P Internet live broadcast service system and method for forming a P2P tree structure according to the number of sessions - Google Patents

Description

  The present invention relates to a P2P system Internet live broadcast service system and method in which a streaming server streams content to a number of peers by a peer-to-peer (P2P) system, and the P2P system streaming is formed in a tree structure.

  In particular, the present invention broadcasts content streaming to a large number of peers using a tree-structured P2P method, and peers participating in the streaming tree structure are closer to a streaming server as their transmission rate (or bandwidth) increases. The present invention relates to a P2P Internet live broadcast service system and method to be arranged.

  In general, Internet live broadcasting is realized by a system in which when a broadcast server transmits broadcast content to a network, a large number of clients receive the content and reproduce it simultaneously. Usually, such a transmission method is called a live streaming method.

  The Video on Demand (VOD) service is a service that supports the transmission of content desired by one client in real time so that the client can play it simultaneously with reception. That is, the VOD service streams different contents to each client. On the other hand, live streaming is characterized in that one content is provided to many clients at the same time.

  For this reason, the Internet live broadcast server needs to simultaneously transmit a large amount of content data to a large number of clients in real time. The simplest live streaming system is a system in which a broadcast server transmits content data 1: 1 with each client. This method has a problem that the load on the broadcast server increases because the broadcast server must individually transmit content data to a large number of clients at the same time. The more clients that request broadcast content, the more likely these issues become.

  For this reason, a P2P-based Internet live broadcasting service has been proposed in which the above-described broadcasting server individually improves the method of streaming to the client, and the client receiving the content retransmits it to another client. .

  An example of a P2P-based Internet live broadcast service is disclosed in the following Patent Document 1 (release date: June 3, 2008) under the title “Real-time Internet broadcast service system and management method thereof”.

  As shown in FIG. 1A, the real-time Internet broadcast service system described in Patent Document 1 includes a group master peer 200 as a broadcast server that receives broadcast content from a broadcast company and transmits corresponding broadcast data, and the group master. Local master peers 210, 212, 214, and 216 that are managed by a peer and transmit the received broadcast data to one or more simple peers that are subordinately coupled in a P2P manner. That is, a large number of simple peers 213 that are subordinately coupled to the local master peer are hierarchized into a tree structure, and broadcast data is transferred using the P2P method. The local master peer is the simplest peer in the highest hierarchy in the tree formed by the multiple simple peers. A large number of simple peers that are subordinately joined with the local master peer form a group. Note that the local master peer also forms a tree structure.

  For example, as shown in FIG. 1A, the group master peer 200 is initially supplied with broadcast content from a broadcast company (not shown). The group master peer 200 transmits the content supplied to the directly connected local master peer 210. The local master peer 210 transmits data to two local master peers 212 and 214 that are directly connected to the lower level of the local master peer 210 at the same time. Each local master peer 212, 214 transmits content to a number of simple peers 213 that are subordinately coupled to it.

  Also, as shown in FIG. 1B, when a simple peer having a tree structure satisfies a predetermined condition, it can be separated from the group to form a unique group. Referring to FIG. 1B, there are eight simple peers subordinate to the local master peer 214, but three of them can be separated to form a unique group. The simple peer 215 at the highest hierarchy in the uniquely separated group becomes the local master peer.

  Particularly, in Patent Document 1, since the tree structure is conditional on a binary tree, the number of subordinate simple peers connected to a local master peer is limited to two. In FIG. 1B, the local master peer 214 has three subordinate simple peers, so one of them is separated. Conversely, if there is only one simple peer directly connected to the local master peer, another group is brought in and directly connected to generate two subordinate simple peers.

  In Patent Document 1, instead of content servers (or group master peers) transmitting broadcast content directly to all clients (or simple peers), clients are formed in a tree structure and directly connected to clients. Only transmit broadcast content. Each client transmits the transmitted broadcast content to another client directly connected to the client. Thereby, the burden on the content server can be reduced. Patent Document 1 can be managed more efficiently by managing a plurality of clients as a group.

  However, Patent Document 1 does not consider individual characteristics such as client performance at all. That is, Patent Document 1 simply determines the size of the tree structure based on the group master peer (in Patent Document 1, the number of peers belonging to the group is the server capacity of the group master peer, the depth of the group tree structure to which the group belongs. And presents a technology that is regulated by the network bandwidth that provides the broadcast data). Since the binary tree is configured in the preferred embodiment of the tree structure, it can be seen that the number of clients directly connected to the lower level of the client is determined to be a fixed number (for example, two). That is, it can be seen that the transmission performance of the client is assumed to be constant.

  However, in the case of an open network such as the Internet, the transmission capability of each client is generally different. That is, some clients may be very slow in transmitting data to other clients while others may be very fast. The difference may be significant, such as several times or several tens of times.

  In addition, the client in Patent Document 1 may have different times for supplying broadcast content depending on the position in the tree. For example, as shown in FIG. 1A, the client of symbol 210 and the client of symbol 213 have different contents supply times. This is because the 213 client further performs two transmissions such as transmission from 210 to 212 and transmission from 212 to 213 as compared with the client of 210, and the time is delayed accordingly.

  However, since Patent Document 1 restricts the number of clients that can be directly connected to the lower layer to two, the depth of the tree becomes large. For this reason, there is a problem that a considerable variation occurs in the delay time between the clients. In particular, Patent Document 1 does not present a technique for allowing all clients to view the same broadcast content at the same time.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a P2P Internet live stream in which a streaming server streams content to a large number of peers using the P2P method, and the P2P method streaming is formed in a tree structure. A broadcasting service system and method are provided.

  Another object of the present invention is to broadcast content streaming to a large number of peers using a tree-structured P2P method. The streaming server increases the transmission rate (or bandwidth) of peers participating in the streaming tree structure. A P2P Internet live broadcast service system and method are provided near the Internet.

  In order to achieve the above object, the present invention comprises a streaming server for streaming content on the Internet, and a number of peers that receive or relay the streaming of content according to a tree-structured P2P scheme, Dividing the transmission rate to its lower peer by the streaming rate of the streaming server to obtain the number of sessions, and forming the tree structure so that a peer with a large number of sessions becomes an upper peer of a peer with a small number of sessions. A characteristic P2P Internet live broadcast service system is provided.

  In the P2P Internet live broadcast service system, the present invention periodically compares the number of sessions between its own upper peer and itself, and if the number of sessions is larger, Reconnect the upper peers of the higher peers as their upper peers, compare the number of sessions between their lower peers, and connect the lower peers with more sessions to the lower peers with lower sessions as the upper peers. It is characterized by commanding.

  Furthermore, the present invention provides the P2P Internet live broadcast service system, wherein the peer divides the transmission rate to its lower peer by the streaming rate of the streaming server, and sets the minimum integer equal to or greater than the divided value as the number of sessions. It is characterized by defining.

  The present invention further includes a management server that stores and manages peers participating in the streaming tree structure as a participation list in a P2P Internet live broadcast service system, and peers that do not participate in the streaming tree structure include: Requesting and receiving a participation list from the management server, connecting one peer belonging to the participation list as its upper peer, and requesting the management server to register itself in the participation list .

  Further, according to the present invention, in a P2P Internet live broadcast service system, a peer that does not participate in the streaming tree structure transmits a content request message to all peers belonging to the received participation list, and first responds. The streaming server is determined as an upper peer if the peer to be determined is determined as its own upper peer or if the upper peer cannot be determined in the participation list.

  Furthermore, the present invention provides the Internet live broadcast service system of the P2P system, wherein the peer transmits its own session number and lower peer connection information to its upper peer, and the lower peer connection information is connected to the lower peer. The peer list includes the number of sessions of each subordinate peer connected and the subordinate peer connection information of each subordinate peer, and the peer located at the top of the tree structure has its own session count and subordinate peer connection information. Is transmitted to the management server.

  Furthermore, the present invention is characterized in that in the P2P Internet live broadcast service system, the peer does not connect lower peers larger than the maximum number of lower peers.

  Furthermore, the present invention is characterized in that in the P2P Internet live broadcast service system, the peer does not connect lower peers if the depth of its own tree is equal to the maximum depth of the tree.

  Further, according to the present invention, in the P2P Internet live broadcast service system, the peer does not connect lower peers if the content to be reproduced in the future is not in the buffer or is smaller than the minimum buffering amount. It is characterized by that.

  Further, the present invention provides the P2P Internet live broadcast service system, wherein the management server receives and stores a maximum delay time, and the peer receives and receives the maximum delay time from the management server. The content is played after the maximum delay time compared to the content streaming time.

  Further, according to the present invention, in the P2P Internet live broadcast service system, in the streaming tree structure, a peer at the lowest level not positioned at the maximum tree depth defines the number of sessions as one. Features.

  Furthermore, the present invention provides the P2P Internet live broadcast service system, wherein the management server sends the streaming to the peer if the number of all lower nodes of the peer at the top of the tree structure is equal to or less than the minimum number of nodes. It is characterized by instructing to reconnect as a lower peer of another peer directly connected to the server.

  In order to achieve the above object, the present invention provides a streaming server for streaming content on the Internet, a number of peers that receive or relay the streaming of the content using a tree-structured P2P method, and the streaming tree. In a P2P Internet live broadcast service method using a management server that stores and manages peers participating in a structure as a participation list, (a) a peer that does not participate in the streaming tree structure has a participation list in the management server. Requesting and receiving and joining one peer belonging to the participation list as its upper peer; (b) the peer playing the received content; and (c) the streaming tree structure Peers participating in are subordinate peers (D) periodically, each peer compares the number of sessions of an upper peer or a lower peer, and a peer with a larger number of sessions Partially reconnecting to become a higher-ranking peer of a small number of peers, and providing a P2P Internet live broadcast service method.

  Further, the present invention is the P2P Internet live broadcast service method, wherein the step (a) includes: (a1) a peer that does not participate in the streaming tree structure requests and receives a participation list from the management server; (A2) the non-participating peer sends a content request message to all peers belonging to the received participation list; and (a3) the non-participating peer sets its first responding peer to its own A step of connecting as an upper peer, and (a4) if the upper peer cannot be determined in the participation list, the step of determining the streaming server as an upper peer.

  Furthermore, in the P2P Internet live broadcast service method according to the present invention, in the step (c), the number of sessions between the upper peer and the own peer is compared. Directs the upper peer of the upper peer to reconnect as its upper peer, compare the number of sessions between its lower peers, and connect the lower peer with more sessions as the upper peer to the lower peer with fewer sessions It is characterized by doing.

  Furthermore, the present invention is the P2P Internet live broadcast service method, wherein in the step (b), the peer receives the maximum delay time from the management server, and the received play of the content is a content streaming time. Compared to the above, it is performed after the delay time.

  Furthermore, in order to achieve the above object, the present invention provides a computer-readable recording medium that records the P2P Internet live broadcast service method in the P2P Internet live broadcast service method.

  According to the P2P Internet live broadcast service system and method according to the present invention, a peer having a large number of sessions (or the number of lower peers) that can be streamed is positioned at the top of the streaming tree structure, thereby deepening the depth of the tree structure. The effect is that the transmission time of streaming can be shortened by shortening the length as much as possible, and in particular, the delay time between peers can be minimized.

It is a figure which shows the structure of the real-time Internet broadcast service system by a prior art. It is a figure which shows the structure of the real-time Internet broadcast service system by a prior art. 1 is a diagram illustrating a configuration of a P2P Internet live broadcast service system according to an embodiment of the present invention. FIG. It is a figure which compares the tree structure of various streaming by the number of sessions. It is a figure which compares the tree structure of various streaming by the number of sessions. FIG. 6 is a diagram illustrating steps in which each peer performs reconnection according to the number of sessions in the P2P Internet live broadcast service system according to an embodiment of the present invention. FIG. 6 is a diagram illustrating steps in which each peer performs reconnection according to the number of sessions in the P2P Internet live broadcast service system according to an embodiment of the present invention. FIG. 6 is a diagram illustrating steps in which each peer performs reconnection according to the number of sessions in the P2P Internet live broadcast service system according to an embodiment of the present invention. FIG. 6 is a diagram illustrating steps in which each peer performs reconnection according to the number of sessions in the P2P Internet live broadcast service system according to an embodiment of the present invention. FIG. 3 is a diagram illustrating a method for limiting the size of a tree using a buffering amount in a P2P Internet live broadcast service system according to an embodiment of the present invention. 3 is a flowchart illustrating a P2P Internet live broadcast service method according to an embodiment of the present invention. 3 is a flowchart illustrating a P2P Internet live broadcast service method according to an embodiment of the present invention.

  Hereinafter, specific contents for carrying out the present invention will be described with reference to the accompanying drawings.

  In the description of the present invention, the same portions are denoted by the same reference numerals, and repetitive description thereof is omitted.

  First, the configuration of a P2P Internet live broadcast service system according to an embodiment of the present invention will be described with reference to FIG.

  As shown in FIG. 2, the Internet live broadcast service system includes a streaming server 30 and a number of peers 51, 52, 53. Note that the Internet live broadcast service system may further include a management server 40.

  The streaming server 30 streams content on the Internet.

  The streaming server 30 is a server that transmits broadcast content to a client (or a peer) in real time. The client (or peer) 51 receives the content in real time and immediately reproduces the content. The term “streaming” is used as compared to the transmission and playback of the entire content first.

  In particular, in the following, streaming may also mean live streaming. As described above, streaming in VOD or the like means that the server transmits different contents to each client. However, since the present invention is intended to be applied to real-time Internet broadcasting performed live, streaming can be narrowly interpreted as live streaming hereinafter. In this case, live streaming refers to streaming that has the characteristic of providing a single content to a large number of clients at the same time in real time.

  The streaming server 30 can store the content directly and perform streaming, or can receive and retransmit the content from a separate content server (not shown). In particular, it may be realized as a server that receives content from various content servers and performs only streaming. Since a technology related to a server for streaming content is a known technology in this field, a specific description thereof will be omitted.

  The peer 51 receives or relays the streaming of the content by a tree-structured P2P method.

  The peer 51 is a kind of client that receives or relays content to be streamed in the streaming server 30. However, the peer 51 can also receive the content from other peers 51.

  The peer 51 is realized by a device having a computer function such as a PC. The peer 51 is a computer device provided with a communication device for communicating with the streaming server 30 and other peers 51, in particular, a P2P communication device, a player for reproducing received content, and the like.

  At least one peer 51 exists, and many peers 51 and the streaming server 30 are connected by a network. The network is preferably any network that can perform the Internet or P2P communication.

  The multiple peers 51 form a tree structure 50 for streaming content. The streaming tree structure 50 is a logical connection structure of content transmission for streaming content. It is distinguished from the physical network connection structure of peers 51 that are physically connected to each other on the Internet.

  Based on FIG. 2, for example, the peer B51 located at the top in the streaming tree structure 50 receives the content from the streaming server 30, and the peer B51 that has received the content is directly subordinate to itself (or connected). Retransmit the content to another peer C51 that has been).

  At this time, in the tree structure 50, a peer in the parent node of the peer is called an upper peer, and a peer in the child node of the peer is called a lower peer. All peers that are subordinate to one peer are referred to as a whole subordinate peer or a subordinate whole peer. Further, the root node of the tree structure 50 is expressed as a peer located at the uppermost level or the uppermost level peer, and a leaf node of the tree structure is expressed as a peer positioned at the lowermost level or the lowest level peer. That is, the uppermost peer B51 is directly connected to the streaming server 30, and the lowermost peer C51 does not have a peer directly connected to the lower level.

  The peer 51 includes a buffer that temporarily stores the received content. By using the buffer, the peer can move the upper and lower peers without interruption during live Internet broadcasting as described above. This is because the designated portions before and after the currently viewed video are stored in the buffer.

  Next, the number of sessions of the peer 51 will be described.

The peer 51 obtains the number of sessions by dividing the transmission rate to its lower peer by the streaming rate of the streaming server. Preferably, the peer 51 divides the transmission rate to its lower peer by the streaming rate of the streaming server, and determines the maximum integer equal to or less than the divided value as the number of sessions. That is, it is obtained by the following formula 1.

  The transmission speed of a peer is a data transmission speed when content is transmitted from a lower peer directly connected to the peer. For example, if the transmission speed of the peer is 1,024 kbps, the peer 51 can transmit 1,024 kbit (about 1 M) per second. It can be said that the transmission speed of a peer is a kind of bandwidth that the peer can transmit. Since the transmission rate of a peer is a rate at which content is transmitted to a lower peer, it usually means a maximum upload rate.

  Streaming speed refers to the speed at which content is streamed. For example, when the transmission speed of content is 300 kbps, the content transmits 300 kbit per second. Generally, when the content is a video, the higher the image quality, the higher the content transmission speed. Usually, the transmission speed of MP3 is 128 kbps, and the AM radio level is about 28 kbps.

  For this reason, the transmission speed of streaming may differ for each content. For this reason, when the number of sessions is determined at the content transmission rate, the number of sessions can vary depending on the content every time. Preferably, the streaming server can determine the transmission rate of the reference content. This is called the streaming speed of the streaming server.

  When the number of sessions is obtained in the above example, the number of sessions = [1,024 / 300] = 3. For this reason, the number of sessions is three. The number of sessions means the number of contents that can be streamed simultaneously. If three contents with a transmission rate of 300 kbps are transmitted at the same time, it is the same as transmitting 300 kbps × 3 = 900 kbps. Therefore, a peer with a maximum transmission rate of 1,024 kbps can transmit three 300 kbps contents at the same time. On the other hand, if the peer transmits 4 at the same time, it is the same as transmitting 300 kbps × 4 = 1,200 kbps. In this case, the total amount of data to be transmitted is 1,200 kbp, but since the maximum bandwidth is only 1,024 kbps, an amount of 176 kbps cannot be transmitted. As a result, at least one of the lower peers cannot normally transmit the content and reproduce it.

  On the other hand, the transmission rate of a peer can be measured while transmitting content to another peer. Preferably, the peer measures the transmission rate while transmitting the content to its subordinate peer. However, a peer that does not have a lower peer cannot measure the transmission rate. Preferably, when the peer does not have a lower peer, the number of sessions is set to 1. In other words, this peer is the lowest peer in the streaming tree structure.

  Further, since the peer is a computer such as a PC and is a single client, it can measure and hold a general upload speed or the like. In addition, when the connection is further made after joining the streaming tree structure and then withdrawing, when the peer structure is changed and the tree structure is changed so that the peer structure is not provided, the peer will increase the transmission speed. Can be predicted. For this reason, preferably, if a peer has a basic transmission rate such as an upload rate, the number of sessions is obtained assuming that the basic transmission rate is its own transmission rate even when there is no lower peer. Since the user environment changes from time to time, the number of sessions is calculated and applied every predetermined time.

  Next, a suitable tree structure according to the number of peer sessions will be described with reference to FIG. In the streaming tree structure according to the present invention, peers with a large number of sessions are arranged at the top of the tree.

  FIG. 3A and FIG. 3B each form a tree with 10 peers arranged. And both of the two trees have one session with 4 sessions, one session with 3 sessions, 2 sessions with 2 sessions, and the rest with 1 session. Have peers. In FIG. 3, (S: 4), (S: 2), etc. of the peer indicate that the number of sessions of the peer is currently 4 or 2.

  In FIG. 3A, the peer with the largest number of sessions is placed at the top, whereas in FIG. 3B, a peer with the number of sessions is placed at the top node of the tree. With this configuration, the depth of the tree in FIG. 3A is 3 while the depth of the tree in FIG. 3B is 4 despite the fact that both of the two trees have the same configuration. It became.

  In other words, by placing peers with a large number of sessions in the upper part of the tree structure, a large number of peers can be connected to the upper part. If there are many peers connected to the upper part, the peers connected in the next part are also increased. To increase. That is, by placing a large number of peers at the top of the tree structure, the tree structure is increased in the horizontal direction (ie, the number of sibling nodes of the tree is increased) and the height is decreased.

  As described in the background section above, since it takes a predetermined time to transmit the content from the upper peer to the lower peer, the time when the upper peer receives the streaming of the content and the time when the lower peer receives the content are mutually Different. The difference between the time when the content is transmitted at the streaming server and the time when the content is received at the peer is called “delay time”.

  If the transmission time between peers is the same, the delay time of each peer is proportional to the depth of the node where the peer is located. For this reason, since the height of the tree of FIG. 3A is lower than that of FIG. 3B, variation in delay time between each peer is reduced. In other words, the variation in delay time between peers is reduced by placing peers with a large number of sessions in the upper part of the tree structure.

  Next, a method for changing the streaming tree structure according to the number of peer sessions will be described with reference to FIG.

  The peer 51 obtains the number of sessions by dividing the transmission rate to its lower peer by the streaming rate of the streaming server 30, and the peer 51 having a larger number of sessions becomes the upper peer 51 of a peer having a smaller number of sessions. Form a structure.

  As will be described later, when a peer that does not participate in the streaming tree structure first connects, it is connected to an arbitrary position in the streaming tree structure. For this reason, in the streaming tree structure, as shown in FIG. 3A, peers with a large number of sessions are not located at the top of the tree from the beginning. This is preferred over connectable peers that show the earliest response to eliminate the initial response delay caused by peers participating in streaming determining the number of sessions they can support and getting into the right place. Because it is connected to.

  Instead, each peer moves a peer with a large number of sessions further up the tree by comparing the number of sessions with the peer directly connected to it. That is, the position of the peer is partially adjusted according to the number of sessions. As described above, if the position of the peer is partially adjusted, finally, as shown in FIG. 3A, the peer structure having a large number of sessions as a whole is changed to a tree structure located at the upper stage of the tree. .

  Partial peer positioning is performed by each peer in the following two ways. The first is to compare the number of sessions between its own upper peer and itself, and the second is to compare the number of sessions between its own lower peers. That is, preferably, the peer periodically (1) compares the number of sessions between its own upper peer and itself, and if there are more sessions, the upper peer of its own upper peer (2) Compare the number of sessions between its own lower peers and instruct the lower peer with a smaller number of sessions to join the lower peer with a larger number of sessions as the upper peer.

  Further details will be described with reference to FIG. FIG. 4 is a diagram illustrating that the order of the four peers participating in the streaming tree structure is changed according to the number of sessions. In FIG. 4, (S: 3) of the A peer indicates that the number of sessions of the peer is 3 at present.

  First, as shown in FIG. 4A, first, peers A, B, and C measure the transmission rate of the peers by transmitting content to peers B, C, and D, respectively, thereby calculating the number of sessions. . On the other hand, the peer D has no transmission target and has 1 as a predesignated value (or default value). That is, the number of sessions of peers A, B, C, and D are 3, 2, 3, and 1, respectively.

  According to the first rule of the partial session number comparison described above, the peer C compares the number of sessions between its upper peer B and itself. That is, the number of sessions of B (S: 2) and C (S: 3) is compared. As a result of comparison, the number of sessions of peer C is larger. Therefore, according to the first rule, peer C reconnects A, which is an upper peer of its upper peer, as its upper peer.

  If reconnected in this manner, the tree structure is changed as shown in FIG. 4B. That is, peer C is connected as a lower peer of peer A. At this time, D that was originally connected to the lower peer of C follows as it is.

  Next, peer A compares the number of sessions of its lower peers B and C according to the second rule of partial session number comparison. That is, the number of sessions of B (S: 2) and C (S: 3) is compared. As a result of comparison, the number of sessions of peer C is larger. For this reason, according to the second rule, the peer C commands the lower peer B having a smaller number of sessions to connect the lower peer C having a larger number of sessions as an upper peer. As shown in FIG. 4C, the lower peer B receives the command from its upper peer A and reconnects the peer C as its upper peer.

  Next, peer C compares the number of sessions of its lower peers B and D according to the second rule of partial session number comparison. That is, the number of sessions of B (S: 2) and D (S: 1) is compared, and since the number of sessions of peer B is larger, peer C has a lower number of sessions with a lower number of sessions. Command Peer B to join as an upper peer. As shown in FIG. 4D, the lower peer D receives the command from its upper peer C and reconnects the peer B as its upper peer.

  Preferably, the change as described above is performed once at a predetermined time interval when the change condition is satisfied, and the tree structure is kept the same when no further change is required.

  Next, in the Internet live broadcast service system of FIG. 2 described above, a description will be given of the participation of a management server 40 and a peer that does not participate in the tree structure using the management server 40 in the tree structure.

  The management server 40 stores and manages peers participating in the streaming tree structure as a participation list. The participation list stores identification information of peers and records which peers participate in the tree structure. The identification information of the peer is information that can identify the peer on the network, and can be expressed differently depending on the network standard. Taking the Internet as an example, peer identification information is defined by an IP address.

  A peer that does not participate in the streaming tree structure requests and receives a participation list from the management server 40, connects one peer belonging to the participation list as its upper peer, and registers itself in the participation list. To the management server 40.

  Preferably, a peer that does not participate in the streaming tree structure sends a content request message to all the peers that belong to the received participation list and defines the first responding peer as its upper peer, or If the upper peer cannot be determined in the participation list, the streaming server is determined as the upper peer.

  One of the reasons for setting the first responding peer as the upper peer is to indicate that the first responding peer is a peer with a higher transmission rate, and the method is simple, and broadcasting can be started quickly. Because. In addition to the above method, it is also possible to select the peer with the smallest number of hops by calculating the number of hops with the peers in the participation list while transmitting / receiving the request message. In other words, any method can be applied as long as it finds a peer having a high transmission rate to be sent to itself.

  Next, a method for limiting the number of lower peers connected to the peer and the depth of the tree will be described.

  It is preferable to limit the number of lower peers directly connected to one peer to a predetermined number (hereinafter, the maximum number of lower peers). The reason is that even if a particular peer's line is good, if too many users are connected, the performance of the system may be degraded. More importantly, if this peer stops relaying content streaming, any lower-level peers that were connected to this peer must reconnect to other peers. As the number of connected lower peers increases, the work for reconnection increases, so that the entire service system is heavily loaded, and the number of peers whose content viewing is interrupted increases. Preferably, the maximum number of lower peers is limited to a range of 5 to 10.

  On the other hand, as described above, the depth of the tree of the streaming tree structure is related to the variation in delay time between the peers. That is, as the depth of the tree increases, the difference in delay time between the uppermost peer and the lowermost peer increases. Therefore, it is necessary to reduce the depth of the tree in order to reduce this delay time.

  In particular, in order for all peers to view (or listen to) content that is streamed at the same time, it must be played after a predetermined time (hereinafter, the maximum delay time) has elapsed from the time the content is sent from the streaming server. I must. Each peer needs to be streamed content within this maximum delay time. It is preferable to reduce the maximum delay time as much as possible. Therefore, it is preferable that the depth of the tree of the streaming tree structure is limited to a predetermined tree depth (hereinafter referred to as the maximum tree depth), and the time for streaming to this tree depth is defined as the maximum delay time.

  Managing the number of lower peers or the depth of the tree as described above is effective in maintaining the quality of Internet live broadcast service at a certain level. Any method of managing only the number of lower peers, managing the depth of the tree, or managing both can be applied.

  In order to manage the number of lower peers or tree depth as described above, each peer manages its connection information along with the number of sessions. The connection information includes a list of lower-level peers directly connected to itself, the number of sessions of each lower-level peer, and connection information. The list for lower peers includes the number of lower peers. Also, the list for the lower peer can include identification information of the lower peer. The connection information of each lower-level peer is information in the same format as its own connection information. That is, the lower peer connection information further includes lower peer connection information of the lower peer. Since the connection information is recursively configured, the connection information includes information on all peers below it.

  On the other hand, each peer can know the depth of its own tree by requesting and receiving the depth of the upper peer tree from the upper peer. That is, the depth of its own tree is obtained by adding 1 to the depth of the tree of the upper peer.

  Also, each peer can calculate the depth of the tree of all lower peers through the connection information of the lower peers. That is, the number of steps below the peer at the lower level is obtained, the relative tree depth is obtained, and the depth of the own tree is added to the relative tree depth. The depth of the peer tree at

  All peers transmit their number of sessions and lower peer connection information to their upper peers. The lower peer connection information includes a connection list of connected lower peers and a session of each connected lower peer. Including the number and concatenation information of the lower peers of each lower peer. The peer located at the top of the tree structure transmits the number of sessions and connection information of the lower peers to the management server 40.

  For this reason, the management server 40 has connection information of all peers included in the streaming tree structure. Each peer has information on all peers connected to its lower level.

  Using the number of sessions and connection information as described above, each peer does not connect more lower peers than the maximum number of lower peers. Also, a peer does not join lower peers if its tree depth is equal to the maximum tree depth.

  Next, it will be described that the tree structure is changed and the connection information is changed when a peer is newly connected or changed.

  If a specific peer terminates abnormally in a specific tree, or if the order is changed or moved depending on the number of sessions of the upper peer, the top peer of the tree that is changed at this time Passes the connection information to all lower trees (all lower peers) to inform the user's connection information, and the peer has the relative position information (upper peer + 1) of the connection information.

  When a tree having a lower peer moves, the management server 40 can consider only the information of connectable peers that do not exceed the maximum tree depth in consideration of the current depth of the peer so that it can be connected. To do. That is, the connected peer knows the depth of the tree to be connected and immediately passes the depth of its tree to all the lower peers after the connection.

  For this reason, in the case of the first peer to be connected, it is possible to connect to any place other than the lowest peer.

  Specifically, a method for limiting the number of lower peers or the depth of the tree is as follows.

  First, a case where a peer that does not participate in the streaming tree structure requests a participation list from the management server 40 in an attempt to participate in the tree structure will be described. In this case, if the number of lower peers or tree depth of the peer among the peers in the participation list is equal to the number of maximum lower peers or the maximum tree depth, the management server 40 excludes the remaining peers. Transmit to only peers that do not participate.

  A case where the tree structure is periodically changed will be described.

  First, a case where the number of sessions between the host peer and the host is compared (first case) will be described. At this time, if the upper peer of its own upper peer has the number of lower peers equal to the number of maximum lower peers, it does not reconnect. This is because the number of lower-level peers exceeds the maximum number of lower-level peers when connected to an upper-level peer of its own upper-level peer.

  Then, the case of comparing the number of sessions between own lower peers (second case) will be described. At this time, if the depth of the tree of the lower peer having a small number of sessions is equal to the depth of the maximum tree, the reconnection is not performed. This is because if the lower peer with a large number of sessions is connected to the lower peer with a small number of sessions, the depth of the tree becomes larger than the depth of the maximum tree.

  Next, a method in which all peers receiving the content view (or listen to) the content at the same time will be described.

  As described above, the P2P live broadcast (or grid broadcast) is delayed due to retransmission between users (or peers). For this reason, when reproduction (viewing or listening) is started immediately after all peers have been transmitted from the upper peer, the peers at the upper and lower levels in the tree structure have different times for reproducing the same content. That is, the peers in the upper part of the tree structure reproduce the content contents in the same time zone first as compared to the peers in the lower part of the tree structure.

  Since the above-mentioned type of live Internet broadcasting can be easily realized, it can be used in the case of retransmitting a TV broadcast, or in the case of a simple broadcast in which there is no major problem even if the broadcast is delayed. Note that when the tree structure is large, a difference in the depth of the tree between the uppermost peer and the lowermost peer is greatly increased, so that the delay time between both peers becomes extremely large.

  More preferably, all the peers can play back with a predetermined time delay from the time of transmission in the streaming server, and the same content can be played back at the same time. Specifically, the management server 40 receives and stores the maximum delay time, and the peer 51 receives the maximum delay time from the management server 40 and compares the received play of the content with the content streaming time. And after the maximum delay time. That is, a delay corresponding to the maximum delay time occurs between the streaming server 30 and each peer 51, but there is no delay difference between the peers 51.

  As described above, the live Internet broadcast that each peer reproduces simultaneously is suitable for use for the purpose of chat or education at the same time by viewing the same screen between users. In this method, the tree structure cannot be larger than a predetermined depth due to transmission delay between peers. The delay tolerance time is determined by the service provider's policy, and the tree level increases as the specified delay tolerance time increases. In this system, interactive broadcasting is possible when all peers watch the same video.

  As described above, since the delay time between the uppermost peer and the lowermost peer increases as the tree grows, the tree needs to be limited to a predetermined size. That is, all peers need to be transmitted content before the maximum delay time.

  As a method for realizing this, there are a method for limiting the maximum tree depth and a method for checking the buffering amount of content in each peer. The method for limiting the depth of the maximum tree is as described above. The latter method will be described with reference to FIG.

  As shown in FIG. 5, it is assumed that three peers 51 are continuously connected to the streaming server 30 respectively. In the server, the peer is A, and the streaming time between each peer is Δt. The maximum delay time is 3Δt.

If the streaming server 30 transmits the _{T 1} portion of the content to the time _{t 1,} peer A at time _{t 1} + Delta] t receives _{T 1} portion of the content. However, since the delay time is 3Δt, Peer A waits until time t ₁ + 3Δt. During this time, peer A continues to receive content transmitted from server 30 and stores it in a buffer. For example, the peer A receives the T ₁ + Δt portion of the content sent from the server 30 at the time t ₁ + Δt at the time t ₁ + 2Δt, and the T ₁ + 2Δt portion of the content sent from the server 30 at the time t ₁ + 2Δt. At time t ₁ + 3Δt. For this reason, when the peer A plays the T ₁ portion of the content at time t ₁ + 3Δt, the peer A receives up to the T ₁ + 2Δt portion of the content and stores it in the buffer.

Similarly, peer B receives the _{T 1} portion of the content to the first time _t 1 + 2? T, when playing _{T 1} portion of the content to the time _t 1 + 3? T, to receive up to _{T 1} + Delta] t part of the content in the buffer save.

Peer C plays the content immediately after receiving the T ₁ portion of the content at time t ₁ + 3Δt. That is, as shown in the example of FIG. 5, if a content to be reproduced in the future by a certain peer 51 is in the buffer, this peer 51 can receive the streaming before the maximum delay time, and thus can have a lower peer. However, if the content that the peer plays is not in the buffer, this peer should not join any lower peers.

  For this reason, preferably the peer does not join the lower peer if there is no future content in the buffer or less than the minimum buffering amount. More preferably, the amount of minimum buffering is determined by the transmission rate to the lower peer. That is, the buffer needs to have the amount of time until transmission to the lower peer and reproduction by the lower peer, that is, the delay time Δt to the lower peer.

  However, since the delay time Δt to the lower peer (or the transmission rate to the lower peer) actually varies depending on the network conditions and the like, it is preferable to use a delay time arbitrarily determined by the administrator's input.

  Next, a description will be given of a process of reconnecting peers and a method of merging between trees when peers participating in the tree structure withdraw or drop off in the middle.

  When a certain peer leaves, the peer directly connected to the peer leaves the tree structure. The peer that has left must look for other peers to join as the upper peer. Preferably, the detached peer requests the participation list from the management server, and selects one of the peers belonging to the participation list, excluding the peer located below itself and the peer, as an upper peer. At this time, the selection method is the same as the above-described method of selecting the upper peer when a non-participating peer participates.

  On the other hand, peers directly connected to the streaming server form a tree structure with peers below them. Therefore, a tree structure corresponding to the number of peers directly connected to the streaming server is formed. However, when the number of peers dropped or withdrawn on the way increases, the number of peers included in the tree structure decreases to a predetermined number (hereinafter, the minimum number of nodes) or less and merges with other trees.

  That is, if the number of all the lower nodes of the peers at the top of the tree structure is equal to or less than the minimum number of nodes, the management server 40 is re-established as a lower peer of other peers directly connected to the streaming server. Command to concatenate. At this time, the management server 40 also transmits information of other peers to be connected. The uppermost peer that has received the command reconnects to the peer received from the management server 40.

  Next, a P2P Internet live broadcast service method according to an embodiment of the present invention will be described with reference to FIG.

  The Internet live broadcast service method participates in the streaming tree structure, a streaming server 30 for streaming content on the Internet, a number of peers 51 that receive or relay the streaming of content according to the P2P scheme of the tree structure 50, and the streaming tree structure. The management server 40 that stores and manages peers as a participation list is used.

  As shown in FIG. 6A, in the Internet live broadcast service method, (a) a peer that does not participate in the streaming tree structure requests and receives a participation list from the management server, and receives one peer belonging to the participation list. Connecting as an upper peer (S10), (b) playing the received content (S20), and (c) a peer participating in the streaming tree structure is subordinate to itself Dividing the transmission rate to the peer by the streaming rate of the streaming server to obtain the number of sessions (S30), and (d) periodically, each peer compares the number of sessions of the upper peer or the lower peer, Partially rejoining a large number of peers to become a higher level peer of a peer with a small number of sessions ( It includes a 40), a.

  Content playback is performed immediately after content buffering after step (a).

  In particular, as shown in FIG. 6B, the step (a) includes the steps (a1): a peer that does not participate in the streaming tree structure requests and receives a participation list from the management server (S11); The non-participating peer sends a content request message to all peers belonging to the received participation list (S12), and (a3) the non-participating peer sets its first responding peer as its top The step of connecting as a peer (S13), and (a4) the step of determining the streaming server as an upper peer if it cannot be determined in the participation list (S14).

  In the step (c), the number of sessions between the host peer and the host peer is compared. If the number of sessions is larger, the host peer of the host peer is reconnected as the host peer. Compare the number of sessions between its own lower peers, and instruct the lower peer with the smaller number of sessions to connect the lower peer with the larger number of sessions as the upper peer.

  In the step (b), the peer receives the maximum delay time from the management server, and plays (or plays) the received content after the delay time compared to the content streaming time.

  For the unexplained portion of the P2P Internet live broadcast service method, refer to the above description of the P2P Internet live broadcast service system.

  Although the invention devised by the present inventor has been specifically described based on the embodiment, the invention is not limited to the embodiment, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

  The present invention can be applied to the field of developing a P2P Internet live broadcast service system in which content is streamed to a large number of peers by the P2P method, and the P2P streaming is formed in a tree structure. In particular, the present invention is applied to a system that is used for the same time chat or education purposes in which all peers must watch the same screen with a predetermined time delay after the server starts transmitting video. Is preferred.

30: Streaming server,
40: Management server
50: Streaming tree structure,
51: Peer.

Korean Patent No. 10-2008-0048835

Claims (15)

A streaming server for streaming content over the Internet;
A number of peers that receive or relay the streaming content in a tree-structured P2P manner;
With
Each peer is
Dividing the transmission rate to its lower peer by the streaming rate of the streaming server to obtain the number of sessions, forming the tree structure so that peers with a large number of sessions become upper peers of peers with a small number of sessions,
Periodically, compare the number of sessions of yourself, the upper-level peer directly connected to you (hereinafter referred to as the upper peer), or the lower-level peer directly connected to yourself (hereinafter referred to as the lower-level peer) to increase the number of sessions. Partially rejoins the peer so that it becomes a higher-ranking peer with fewer sessions ,
Compare the number of sessions between your top peer and yourself, and if there are more sessions, reconnect the top peer of your top peer as your top peer,
A P2P Internet live broadcast service system characterized by comparing the number of sessions between its own lower peers and instructing a lower peer having a smaller number of sessions to connect a lower peer having a larger number of sessions as an upper peer . The peer is
2. The P2P Internet live broadcast service system according to claim 1, wherein a transmission rate to the lower peer is divided by a streaming rate of the streaming server, and a maximum integer equal to or less than the divided value is determined as the number of sessions. . A management server for storing and managing peers participating in the streaming tree structure as a participation list;
A peer that does not participate in the streaming tree structure requests and receives a participation list from the management server, connects one peer belonging to the participation list as its upper peer, and registers itself in the participation list. Internet live broadcast service system of P2P system according to claim 1, characterized in that the request to the management server. Peers that do not participate in the streaming tree structure
Send a content request message to all peers belonging to the received participation list and define the first responding peer as its own upper peer, or if it is not possible to determine an upper peer in the participation list, 4. The P2P Internet live broadcast service system according to claim 3 , wherein the streaming server is defined as an upper peer. The peer transmits its own session number and lower peer connection information to its upper peer, and the lower peer connection information includes a connection list of connected lower peers, the number of sessions of each connected lower peer, and Contains the connection information of the lower peer of each lower peer,
4. The P2P Internet live broadcast service system according to claim 3 , wherein the peer located at the top of the tree structure transmits the number of sessions and connection information of lower peers to the management server. The peer is
6. The P2P Internet live broadcast service system according to claim 5 , wherein lower peers than the maximum lower peer number are not connected. The peer is
6. The P2P Internet live broadcast service system according to claim 5, wherein the lower peer is not connected if the depth of the tree is equal to the maximum tree depth. The peer is
6. The P2P Internet live broadcast service system according to claim 5 , wherein if the content to be reproduced in the future is not in the buffer or if the content is smaller than the minimum buffering amount, the lower peer is not connected. The management server receives and stores a maximum delay time;
The peer receives the maximum delay time from the management server, to claim 7 or claim 8, characterized in that after the maximum delay time than playing the received the content to the content streaming time The P2P Internet live broadcast service system described.   2. The P2P Internet live broadcast service according to claim 1, wherein in the streaming tree structure, a peer at the lowest level not positioned at the maximum tree depth defines the number of sessions as one. system. The management server
If the number of all subordinate nodes of the peer at the top of the tree structure is less than or equal to the minimum number of nodes, the peer is instructed to reconnect as a subordinate peer of another peer directly connected to the streaming server. The P2P Internet live broadcast service system according to claim 3 , Management for storing and managing a streaming server for streaming content on the Internet, a number of peers that receive or relay the streaming of the content by a tree-structured P2P method, and peers that participate in the streaming tree structure as a participation list In a P2P Internet live broadcast service method using a server, (a) a peer that does not participate in the streaming tree structure requests and receives a participation list from the management server, and receives one peer belonging to the participation list. Connecting as your top peer,
(B) the peer reproduces the received content;
(C) a peer participating in the streaming tree structure obtains a session by dividing the transmission rate to its lower peer by the streaming rate of the streaming server;
(D) Periodically, each peer compares the number of sessions of itself, an upper level peer directly connected to itself (hereinafter referred to as an upper peer), or a lower level peer directly connected to itself (hereinafter referred to as a lower peer). Partially rejoin the peer with a higher number of sessions to be the higher peer of the peer with a lower number of sessions ,
Compare the number of sessions between your top peer and yourself, and if there are more sessions, reconnect the top peer of your top peer as your top peer,
Compare the number of sessions between your lower peers and instruct lower peers with fewer sessions to join lower peers with more sessions as upper peers
Steps,
A P2P Internet live broadcast service method comprising: The step (a) includes:
(A1) a peer that does not participate in the streaming tree structure requests and receives a participation list from the management server;
(A2) the non-participating peer transmits a content request message to all peers belonging to the received participation list;
(A3) the non-participating peer connects the first responding peer as its upper peer;
(A4) If the upper peer cannot be determined in the participation list, the step of determining the streaming server as an upper peer;
13. The P2P Internet live broadcast service method according to claim 12 , further comprising: The step (b)
The P2P Internet according to claim 12 , wherein the peer receives the maximum delay time from the management server and plays the received content after the delay time compared to a content streaming time. Live broadcast service method. Readable recording medium by a computer which records a program for executing the Internet live broadcast service method of P2P system according to the computer of claims 12 to claim 14.

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