Realtime media distribution in a P2P network

FIELD OF THE INVENTION

0001The present invention relates generally to the field of network communications and media distribution. More specifically, the present invention is related to a system and method for improving realtime media delivery in a distributed peer-to-peer (p2p) or grid network.

BACKGROUND OF THE INVENTION

0002The availability of the Internet enables new methods of directly distributing multimedia files and realtime media transmission to end-users in an electronic format. The advantages associated with electronic distribution are pushing providers of media content to establish global distribution systems for digital content.

0003The availability of new compression algorithms for multimedia data has dramatically reduced the bandwidth and storage space required for the electronic distribution of these data. It enables a more efficient distribution of the data, and at a higher definition. In the coming years, the availability of broadband will encourage a significant part of the media industry to adopt the Internet as a distribution channel in direct competition with established channels such as cable or satellite TV.

0004Prior art systems provide various ways for transmitting multimedia such as voice and video over the Internet. Real-time streaming systems over the Internet, such as Microsoft, Real-Networks, SeaChange, and Broadbus deliver systems for real-time streaming content over the Internet. However, all of these systems operate in a 'centralistic' mode in which a server located in one point delivers the media (realtime or to be downloaded first and watched later) to the content consumers. One drawback associated with such prior art systems is the need to allocate bandwidth in the center to satisfy the needs of the consumers.

0005Distributed networks enable the media to be transmitted from one consumer to another without the need for centralistic streaming servers. As an example, peer-to-peer file sharing systems for PCs are well known in the industry and are a very efficient technology that can be used to deliver media content in a legitimate manner (such as AOL HI-Q, BBC) to complement or replace traditional client-server download or streaming. Examples for such peer-to-peer systems are Bittorrent and Gnutella. All of the above systems do not distribute the files (media or software) in realtime. User can download the files and consume them afterwards, but, generally speaking, they cannot consume the media while downloading it.

0006Realtime streaming over a peer-to-peer network is a new phenomenon and examples of such systems are Coolstream (proposed in <nplcit id="ncit0001" npl-type="s"><text>2004 by Xinyan Zhang et. "Coolstream: A Data Driver Overlay Network for Efficient Live Media Streaming</text></nplcit>), and CollectCast: (proposed in 2003 by <nplcit id="ncit0002" npl-type="s"><text>Hefeeda et all "PROMISE: peer-to-peer media streaming using CollectCast" in Proc. Of ACM Multimedia 2003 pages 45-54</text></nplcit>). However, these systems do not take into consideration the asymmetric nature of the real-world network, thus the fact that common values of upload bandwidth from nodes in the real-world network versus the download limits of the nodes. As an example, in ADSL network, as well as in Cable networks, the download bandwidth supplied to the users is lower than their available upload bandwidth.

0007There is, thus, a need in the art, to introduce the concept of nodes that act in the role of Amplifiers and upload more bandwidth to the network than the one they download.

LIST OF RELATED ART:

US 6,088,360 : Dynamic rate control technique for video multiplexer

0008A video multiplexer is disclosed which incorporates a dynamic rate control feature. MPEG encoded video signals for each channel are stored in a first-in first-out (FIFO) buffer. A packetizer for each channel detects the level in the FIFO buffer and issues a request signal to the video multiplexer that the channel desires to transmit the video signals on the network. The bandwidth allocation for a channel is either preselected by the video provider or automatically selected, and tokens are issued by a counter associated with each channel to give greater network access to those channels which require a higher bandwidth. A token multiplier detects the bandwidth needs of the various channels by detecting the rate that the FIFO buffer is being filled and automatically multiplies the number of consecutive packets which the packetizer may transmit over the multiplexer during a single grant.

US 2005/00883842: Method of performing adaptive connection admission control in consideration of input call states in differentiated service network

0009In the adaptive connection admission control method of the present invention, a corresponding ingress edge node performs connection admission control for a new connection within the amount of bandwidth initially allocated to each of paths between the ingress and egress edge nodes. The amount of remaining bandwidth allocated to a specific path Pr is compared with an amount of bandwidth required for a call requesting new connection setup input to the corresponding ingress edge node. The amount of additional bandwidth to be requested from the bandwidth broker is predicted when the amount of the remaining bandwidth does not satisfy the amount of bandwidth required for the connection setup requesting call. The ingress edge node requests additional bandwidth from the bandwidth broker on the basis of the predicted amount of the additional bandwidth, changing bandwidth information of the corresponding path Pr, and performing connection admission control.

US 2006/0080454: System and method for receiver-driven streaming in a peer-to-peer network

0010A "PeerStreamer" provides receiver-driven peer-to-peer (P2P) media streaming for loosely coupled P2P networks. Peers in the network perform only simple operations, may cache all or part of the streaming media, do not collaborate with other peers, may be unreliable, and may drop offline or come online during any given streaming session. Clients in the network operate in real-time to coordinate peers, stream media from multiple peers, perform load balancing, handle online/offline states of peers, and perform decoding and rendering the streaming media. In one embodiment, the PeerStreamer uses high rate erasure resilient coding to allow multiple serving peers to hold partial media without conflict, such that clients simply retrieve fixed numbers of erasure coded blocks regardless of where and what specific blocks are retrieved. In another embodiment, the PeerStreamer uses embedded coded media to vary streaming bitrates according to available serving bandwidths and client queue status.

US 2006/0224687 A1: Method and apparatus for offline cooperative file distribution using cache nodes

0011Methods and apparatus are provided for cooperative file distribution system employing one or more storage proxies to allow an offline receiver to obtain files or pieces thereof when the receiver comes online. A central tracker receives an indication from the sender that the sender has the file; determines if the receiver is online; and initiates a storage of the file on one or more storage proxies if the receiver is not online. A proxy service can identify one or more potential storage proxies that can store the file and that each satisfy one or more predefined resource criteria. The sender can send a request to one or more of the storage proxies from the list of storage proxies to act as a storage proxy for the communication between the sender and the receiver. The potential storage proxies compare one or more resource measures to predefined criteria; and provide an acceptance if the one or more resource measures satisfy the predefined criteria.

US 2006/0242315 Al: System and Method for Intelligent Buffering and Bandwidth Allocation

0012A method comprises generating a bitrate template comprising a histogram of bitrate as a function of time for each of a plurality of previously-encoded multimedia programs, each bitrate template indicating actual bitrate requirements for every given point of time within the associated multimedia program, and, prior to transmitting one of the plurality of media programs to a multimedia node, identifying the previously- generated bitrate template for said multimedia program, and, during transmission of said multimedia program, changing a bandwidth allocation for the multimedia node in anticipation of an actual bitrate spike indicated in the bitrate template for said multimedia program.

0013<nplcit id="ncit0003" npl-type="s"><text>TRAN M ET AL: "Peers-assisted Dynamic Content Distribution Networks" of the PROCEEDINGS OF THE IEEE CONFERENCE OF LOCAL COMPUTE NETWORKS 30TH ANNISVERSARLY (LCN'05), 2005, Pages 1-8</text></nplcit>, XP10859179.

0014In this paper, it is proposed that a Content Distribution Network (CDN) is being agile while delivering content. A case is made for a dynamic CDN architecture in which a CDN leverages local peers to deliver the CDN's content to local users. A formal problem for using peers to increase the capacity of a CDN is defined and an algorithm to help a CDN to dynamically recruit local peers to be part of the CDN is proposed. The CDN and the recruited local peers cooperate to serve content to other local users.

SUMMARY OF THE INVENTION

0015The present invention provides a system with the features of present claim 1, a method with the features of present claim 14, a computer program as defined by claim 17 and an amplifier node with the features of claim 18, to enable realtime transmission of media in a distributed network (also known as peer-to-peer or grid network). Preferred embodiments are disclosed in dependent claims. The system and method of the invention dynamically discover the need for additional bandwidth and provide the needed bandwidth by allocating resources from other devices that are connected to the overlay network. In accordance with certain embodiments, these additional devices that share their bandwidth but do not consume the media (e.g do not watch the stream) are referred to as Amplifiers. In addition to the amplifiers, the network and the swarm contains also Consumers which are nodes (and usually users) that are consuming e.g. watching the media. Note that consumers share their upload bandwidth as well as Amplifiers.

BRIEF DESCRIPTION OF THE DRAWINGS

0016In order to understand the invention and to see how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: <ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">Figure 1</figref> illustrates the hardware diagram of the system, in accordance with certain embodiment of the invention;</li><li><figref idref="f0002">Figure 2</figref> illustrates the general architecture of the system, in accordance with certain embodiment of the invention;</li><li><figref idref="f0003">Figure 3-A</figref> illustrates exemplary operational scenarios, in accordance with an embodiment of the invention;</li><li><figref idref="f0004">Figure 3-B</figref> illustrates exemplary operational scenarios, in accordance with an embodiment of the invention;</li><li><figref idref="f0005">Figure 3-C</figref> illustrates an exemplary operational scenario, in accordance with an embodiment of the invention;</li><li><figref idref="f0006">Figure 4A</figref> illustrates a general flow chart of a sequence of operation in the system, in accordance with a certain embodiment of the invention;</li><li><figref idref="f0007">Fig. 4B</figref> illustrates a sequence of operation of a server logic in accordance with an embodiment of the invention;</li><li><figref idref="f0008">Fig. 4C</figref> illustrates a sequence of operation of a server logic in accordance with an embodiment of the invention;</li><li><figref idref="f0009">Figure 5</figref> illustrates a flow chart of the mechanism and parameters to add an amplifier to the swarm, in accordance with certain embodiment of the invention;</li><li><figref idref="f0010">Figures 6A</figref>, <figref idref="f0011">6B, 6C</figref> illustrate the amplifier's logic, in accordance with a certain embodiment of the invention;</li><li><figref idref="f0012">Figure 7</figref> illustrates a flow diagram of the amplifier's scheduling parameters algorithm, in accordance with a certain embodiment of the invention; and</li><li><figref idref="f0012">Figure 8</figref> illustrates the usage of the XOR mechanism, in accordance with a certain embodiment of the invention.</li></ul>

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

0017Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Generally (although not necessarily), the nomenclature used herein described below are well known and commonly employed in the art. Conventional methods are used for these procedures, such as those provided in the art and various general references. Accordingly, the following definitions are provided for clarity of understanding only and are by no means binding: <b><i>"File sharing"</i></b> includes: sharing and distributing files to other users over an electronic network.

0018<b><i>"Node"</i></b> includes: an addressable device or an entity connected to a network or connected to a group. For example, a data download reception unit, a user, a device, an operator, a portable multimedia device, or a server can be referred to as a node. Node may also refer to a module of a software system such as, for example, a media player application.

0019<b><i>"Peer"</i></b> is an equivalent name for Node. However, the term "peers" is used to refer to the group of nodes connected to a specific node from the specific node's perspective.

0020<b><i>"Swarm"</i></b> includes: a group of many nodes all of which participate in the same media distribution. In the particular case of electronic networks and/or peer-to-peer networks, a swarm may refer to a group of nodes participating in the data transfer of one identified, common media object. A node can be part of different swarms when transferring multiple media objects. For example, a peer can be part of swarm #1 (distributing TV program #A) and swarm #2 (distributing movie #B). Sometimes this is referred toalso as <b><i>"overplay network"</i></b>.

0021<b>"<i>Amplifier"</i></b> includes: a node in the swarm whose role is to increase the total swarm bandwidth. The amplifier's main goal is thus to download a given amount of bandwidth and to contribute (upload) a larger amount of bandwidth to other nodes that are either consumers of the media or amplifiers themselves. The relationship of the download stream and upload stream of the amplifier is termed the 'Gain'.

0022<b><i>"Bootstrap amplifier"</i></b> includes an amplifier that may remain with a negative Gain in order to guarantee that to a swarm with no consumers, newly added consumers will have enough bandwidth to start with. Bootstrap amplifier typically (although not necessarily) never shuts down even if its gain is negative. The reason for having bootstrap amplifiers in the system is to provide newly joined nodes with an immediate service.

0023<b>"<i>Gain</i>" -</b> includes: the upload bandwidth of an amplifier minus the downloaded bandwidth by it; an Amplifier tries to maximize its gain. An Amplifier with a negative gain will shut down unless it is a Bootstrap Amplifier.

0024<b><i>"Consumer"</i></b> includes: a node in the swarm usually used by users/viewers to watch the media.

0025"<b><i>Realtime distribution of Media" also called "Streaming"</i></b> includes the following meaning: data is a continuous flow of data that must be ultimately presented to a user in a particular sequence in real time. Moreover the flow of data should be presented to the user close to the time it was transmitted from the media source. Digital samples representing an audio signal, for example, must be converted to a sound wave in the same sequence they were transmitted, and at exactly the time spacing they were generated, or some user-specified alternative. Digital data representing video frames require assembly into the proper sequence in the frame for presentation on a display together, and successive frames must display at the correct real-time rate. Realtime distribution may refer to live events and also to pre-generated content that is consumed while being delivered. Realtime distribution of Media (Streaming) can be realized in various known <i>per se</i> techniques.

0026In the description herein, the term "viewer" is construed to include a real-world user who is watching the media and the term "broadcaster" is construed to include the entity (user or community or an automatic agent) transmitting the media. "Client" is construed to include the software or hardware component to watch the media.

0027In the context of the above referred to definition of node, this term also includes, in accordance with certain embodiments, an entity in the system that is participating in the media delivery itself. A node can have different roles in the transmission of the media: a consumer - whose main object is to fetch the media for the viewer; and an amplifier - whose main objective is to help consumers by contributing its bandwidth to the swarm.

0028In certain embodiments, the nodes are connected to a server that controls the Amplifiers by allocating certain ones and assigning them the role of bootstrap amplifiers.

0029In certain embodiments, media transmission and its control is done in a distributed way within the distributed nodes, e.g. using known per se Mechanisms as described in Ganesh Gossip.

0030Bearing these definitions in mind (provided for clarity in a non-binding fashion), it is noted that the invention is illustrated and described in a preferred embodiment but it may be produced in many different configurations, forms and materials. There is' depicted in the drawings, and will herein be described in detail, various embodiments of the invention, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and the associated functional specifications for its construction, and is not intended to limit the invention to the embodiment illustrated. Those skilled in the art will envision many other possible variations within the scope of the present invention.

0031Attention is first drawn to <figref idref="f0001">Figure 1</figref> illustrating the hardware diagram of the system, in accordance with a certain embodiment of the invention.

0032Thus, the system comprises a broadcasting apparatus (101) that has the media and can be accessed by nodes in the network that may request the media or pieces of it. The broadcasting apparatus can also transfer the media itself to other devices in the electronic network. The media may be a live stream or files accessible to the device. There are several possible ways to implement this apparatus such as, for example, a computer, a media center PC, a personal video recorder, a networked DVD player, a computer with access to a website, a portable media player, a PDA, a mobile phone, or equivalent devices. There may be one or more apparatuses that can be used for one or more users.

0033The broadcasting apparatus(es) are connected to an electronic network (103), such as the Internet or mobile network, in order to make the content and the information about the content available for nodes to download.

0034A server (102) or equivalent processing device can receive and process the information received from one or more broadcasting apparatuses (such as the channel's playlist, the shows, the files, and similar). In certain embodiments, the media itself may not be distributed via the server. There may be multiple instances of these servers in the system.

0035The receiving devices (104, 105) are capable of receiving and transmitting the data forming a media content in a broadcast/multicast transfer or a peer-to-peer transfer. When operating in a peer-to-peer mode, each receiving device is a potential source or sink of data for one or more other receiving devices. Software is usually present on this device so that the device can also operate as the media player. The receiving devices (104, 105) are capable of rendering the content in a direct play-back session (wherein the media player renders the content selected by the user) or in an indirect playback session. A computer, a media center PC, a server, a router, a television with an electronic programming guide, a personal video recorder, a networked DVD player, a computer with access to a website, a portable media player, a PDA, a mobile phone, or equivalent devices are examples of receiving devices.

0036Note that the invention is not bound by the system architecture described with reference to <figref idref="f0001">Fig. 1</figref>.

0037In the description below, reference is occasionally made to the operation of the server, in particular in the context of determining whether there is a need to provide bandwidth support to a given channel(s) by allocating amplifier(s) nodes, and if in the affirmative, to identify the appropriate amplifier nodes that are applicable. In this context, attention is drawn to <patcit id="pcit0001" dnum="US60847677B"><text>US patent application 60/847,677 dated September 29, 2006</text></patcit> entitled "Method and System for Real-Time Streaming Over a Grid Network" (hereinafter the architecture application) whose contents is incorporated herein by reference, and to the non-limiting examples to <figref idref="f0002">Figs. 2</figref> and <figref idref="f0009">Figs. 5</figref> of the application as well as to <figref idref="f0007">Fig. 4B</figref> and <figref idref="f0008">Fig. 4C</figref> below.

0038Bearing this in mind, attention is drawn to <figref idref="f0002">Fig. 2</figref>, illustrating the general architecture of the system, in accordance with a certain embodiment of the invention.

0039Thus, the Server (201) is connected to all devices, including the broadcaster (202) that transmits the media or parts of herein. The transmission of the media may be a live transmission of live events (such as sports, news, concerts), or live transmission of pre-generated content (such as old-movies), or simply transmission of content that may be consumed later on and is being stored on DVR or similar devices. In accordance with certain embodiments, realtime transmission (streaming) of the media to the consumers is improved. Thus, the Broadcaster (202) and the Amplifiers (204) are helping the realtime transmission of the media to the consumers (203) that are watching the media or saving it. All these nodes constitute the Swarm (206) of that specific media transmission/file sharing/TV channel. In addition to the nodes (consumers and amplifiers and broadcasters) in the swarm (206), other nodes (205) may be connected to the server, and are currently neither consuming nor helping (as amplifiers) this specific swarm and this media transmission. Note that these nodes may be parts of other swarms by consuming, amplifying, or even broadcasting another media file or TV channels.

0040It should be further noted that although in certain embodiments, the server is accessed by all nodes and has a central role in the system, in accordance with other embodiments there is provided a complete (or partial) distributed mechanism, using for example Gossip protocols (by Ganesh and others). In such embodiments the information peers management is all done by the nodes in the network without the intervention of a server in the middle.

0041Note that the invention is not bound by the system architecture described with reference to <figref idref="f0002">Fig. 2</figref>.

0042Before moving on, there follows an exemplary operational scenario (with reference to <figref idref="f0003 f0004 f0005">Fig. 3</figref>) for illustrating the role of amplifier, in accordance with an embodiment of the invention.

0043Thus, <figref idref="f0003">Fig. 3A</figref> describes a situation in which 6 viewers (303a,b,c,d,e,f) would like to watch a transmitted show but the broadcaster (301) does not have the required upload bandwidth to support all of them, for example if the video stream is of 800Kbps (namely download rate is 800Kbps per each one of the specified viewers, giving rise to a total of 4.8Mbps) and the broadcaster upload is only of 2Mbps, it readily arises that only 2 (out of six) viewers are supported (total of 1.6Mbps) and only partially the third viewer (until the maximum 2Mbps upload is consumed). The amplifiers 302a,b,c (user's client that are not watching the stream) receive parts of the media and stream it (upload it) to the actual viewers. If every amplifier also has, say 2Mbps upload (total 6Mbps) then the total upload provided by them is sufficient to support the group of viewers (requiring a total of 4.8Mbps download rate). As a result, by adding Amplifiers, e.g. nodes that do not watch the channel but help in its transmission, the system managed to support the 6 viewers.

0044The invention is not bound by the specified example of <figref idref="f0003">Fig. 3A</figref>.

0045Consider the following additional non limiting example, with reference to <figref idref="f0004">Fig. 3B</figref>. Assume 100 viewers (e.g. nodes 3001- 3100 that serve viewers- of which nodes 3001,3002,3003...3100 are shown) who wish to watch a movie or a TV channel that requires an average of 800 Kbits/sec (i.e. download bandwidth of 800 Kbits/sec). Further assume that the each node has an upload bandwidth of 200 Kbits/sec. The upload link between node 3001 and 3002 is marked 3001a, the upload link between node 3002 and node 3003 is marked 3002a, and so forth. The overall bandwidth needed for upload is 100*800 Kbits/sec but the maximum bandwidth available for upload is only 100*200 Kbits/sec. Note incidentally, that by this example, each node holds sufficient volume of media for supporting the maximum upload bandwidth of 200Kbits/sec to a mating node (through the specified channels (3001a, 3002a, ... 3100a.)

0046In accordance with certain embodiments, a mechanism discovers the lack of bandwidth and assigns additional Amplifiers (by this example 3101, 3102 and onwards) to join the media distribution swarm and to contribute their upload bandwidth to it. In order to be efficient, these Amplifiers will have to download less than they upload and to supply the supplemental bandwidth for completing the required missing bandwidth of 100*600 Kbits/sec. Thus, for example, if an average Amplifier uploads 200 Kbits/sec and downloads only 50Kbits/sec, the number of additional Amplifiers will have to satisfy the following equation: <maths id="math0001" num=""><math display="block"><mfenced><mi>The Download needed</mi></mfenced><mspace width="1em" /><mn>100</mn><mo>⁢</mo><mi>viewers</mi><mo>*</mo><mn>800</mn><mo>⁢</mo><mi>Kbps</mi><mo>+</mo><mi mathvariant="normal">A</mi><mo>*</mo><mn>50</mn><mo>⁢</mo><mi>Kbps</mi><mo>=</mo><mfenced><mi>The Upload available</mi></mfenced><mspace width="1em" /><mn>100</mn><mspace width="1em" /><mi>viewers</mi><mo>*</mo><mn>200</mn><mo>⁢</mo><mi>Kbps</mi><mo>+</mo><mi>A</mi><mo>*</mo><mn>200</mn><mo>⁢</mo><mi>Kbps</mi><mo>+</mo><mi>Broadcaster upload</mi><mspace width="1em" /><mn>2</mn><mo>⁢</mo><mi>Mbps</mi></math><img file="EP2005704B1_D0001.tif" /></maths>

0047Thus, A*(200-50) Kbits/sec + 2000 = 100*(800-200) Kbits/sec => A = 387 (For simplicity and if it is assumed that the broadcaster upload to be insignificant the rounded number is 400 Amplifiers).

0048By average, three amplifiers will be assigned to each client node and will feed the required supplemental bandwidth, considering that each amplifier can upload 200 Kbits/sec and that the missing bandwidth is 600Kbits/sec for each consumer node. Assuming, for instance, that broadcast station 3500 can upload at least 2Mbits/sec, it thus supports the download rate (50Kbits/sec) of 40 amplifiers, designated in <figref idref="f0004">Fig. 3B</figref> as 3101 to 3140.

0049Since, as specified above, nearly 400 amplifiers are required to feed the missing bandwidth, additional layer of amplifiers (designated schematically as 3200) can be used. This layer may include 160 amplifiers that are coupled to the 40 amplifiers 3101 to 3140. Each one of the amplifiers 3101 to 3140 has an upload rate of 200Kbits/sec and can thus "support" four amplifiers in layer 3200, each downloading 50Kbits/sec, giving rise to the specified 160 amplifiers at layer 3200. This however is still not enough, since as specified above there are required nearly 400 amplifiers altogether. Now additional level of amplifiers can be used (designated generally as 3300) such that each amplifier in layer 3200 can support (having upload rate of 200Kbits/sec) up to 4 amplifiers in layer 3300 (each having download rate of 50Kbits/sec). Layer 3300 has thus 640 amplifiers considerably more than the required 387 amplifiers for supporting also the 100 consumers 3001-3100. In <figref idref="f0004">Fig. 3B</figref>, <figref idref="f0003 f0004 f0005">3</figref> Amplifiers in layer 3300 (not shown) upload media data to node 3001, through channels 3301a, 3302a and 3303a giving rise to a total of 600Kbits/sec. Each of the Amplifiers will download its respective 50Kbits/sec content from amplifiers in layer 3200 Note that there are 300 amplifiers that are needed in order to support the missing bandwidth of the 100 consumers. However, the specified analysis showed that nearly an additional 400 amplifiers are required. The difference in number of amplifiers (387 vs. 300) is required in order to compensate for the limited upload bandwidth that the broadcaster can provide (only 2 Mbits/sec) whereas the required bandwidth that is required for download by the consumer nodes is considerably higher, i.e. 100 * 800 Kbits/sec.

0050Note that the example of <figref idref="f0004">Fig. 3B</figref> is simplified for clarity only and therefore should not be regarded as binding. For instance the topology of the nodes does not necessarily comply with tree data structure and accordingly any form of graph is applicable. By way of another example, it is not mandatory to have each node uploading another node and few amplifiers completing the required bandwidth. Thus, by way of non-limiting example, a given node may receive media from few uploading peers and the supplemental media (if required) from 0 or more amplifiers, whereas another node may receive the desired media only from amplifiers, etc. By still another non-limiting manner it is obviously not mandatory to have some ordered manner of providing media. Likewise, providing media from a node to a neighboring node (e.g. 3001 to 3101, and 3101 to 3102, etc.) are provided by way of example only. Still further it is not required that each amplifier will have the same download/upload rate. Those versed in the art will readily appreciate that other variants are applicable, all as required and appropriate.

0051Bearing this in mind, attention is drawn to <figref idref="f0005">Fig. 3C</figref> illustrating an exemplary operational scenario, in accordance with an embodiment of the invention. <figref idref="f0005">Fig. 3C</figref> illustrates in a more generalized fashion a broadcast node 30000 (out of few possible available broadcasters- not shown), and a network of plurality of nodes 30001 that receive an upload media from broadcaster 30000 through link 30002 from among the nodes in the network a swarm 30003 includes few nodes marked as 'X' (30004, 30005, 30006and 30007). The nodes have a incoming double arrow, say 30008 and 30009 and a outgoing single arrow, say 30010 and 30011, indicating that the download rate (incoming arrow) is higher than the upload rate (outgoing arrow). Also shown are a few amplifier nodes marked as '0' (30012, 30013,30014). The nodes have a incoming single arrow, say 30015, 30016 and 30017 and a outgoing double arrow, say 30018, 30019 and 30020, indicating that the download rate (incoming arrow) is lower than the upload rate (outgoing arrow). The drawing does not show any specific link between the peers (and therefore does not set a specific topology) indicating that any known <i>per se</i> connection is applicable. The amplifiers will be assigned by the server to the peers based on a need to assist in supplying the desired bandwidth, e.g. in compliance with the specified architecture application.

0052The invention is of course not bound by the specified examples and <i>a fortiori</i> not to the specific architecture and allocation of Amplifiers to nodes.

0053Bearing this in mind, attention is drawn to <figref idref="f0006">Fig. 4A</figref>, illustrating a general flow chart of a sequence of operation in the system, in accordance with a certain embodiment of the invention.

0054Thus, all nodes 404A, 404B, 403X, and 403Y are connected to the system either as consumers, amplifiers, or broadcasters. 404A and 404B are part of the swarm that transmits media content such as TV channel, a movie, or other; 403X and 403Y are connected to the system but are not part of the same swarm (they may be part of other swarms). All of these nodes send periodic information (<b>1</b>) to the server 401. This information is of a statistical nature regarding the node's role and several other parameters regarding the node's status (video quality, number of peers connected). A message can be sent for every specified time such as 10 seconds.

0055There follows a description of a flow in which device 402 would like to join the swarm described as a consumer. Note that an Amplifier may also send the 'joining' request, most likely after an indication for the need to add amplifiers was received by it after being originated by some entity in the swarm, see e.g. <figref idref="f0002">Figure 2</figref> in Architecture application describing calling of the new amplifier, and <figref idref="f0009">Figure 5</figref> describing the flow in which the server evaluates the status and calls a new amplifier. Initially, the device 402 sends a request verb (<b>2</b>) indicating its wish to join the media's swarm and the role it is to take. Thus, if it is a consumer node, this is triggered by a viewer who wishes to join the channel and if it is an amplifier, the server has triggered the operation (see, e.g. <figref idref="f0002">Fig. 2</figref> and <figref idref="f0009">5</figref> of the architecture application). The server sends back an acknowledgement (response) verb (<b>3</b>) after authenticating the device/user and authorizing the request in a known <i>per se</i> manner. The server also sends back a list of nodes to combine the device's group of peers. This group is a subset or equal to the channel's swarm nodes and includes the best subgroup of the nodes to contribute the specific device's needs. As an example, if the device joins the swarm as a consumer, the server will send back a group of nodes from the swarm that have enough bandwidth to contribute to the device.

0056The device then (<b>4</b>, <b>5</b> and <b>4</b>', <b>5</b>') connects to the peers (or to a subset of which) and asks them to participate in the media transmission. The node starts then to request information about the segments (media content pieces) acquired by the peers it is connected with. The exchange of the information is called the 'Segment Information Exchange'. The media itself is not exchanged at this stage, but only the information about it. For instance, and by way of non-limiting example the information may include a bit value which, when set, indicates that data is available, and when reset, indicates that data is not available. The information may further include data indicative of the type of data, say audio, video etc. Accordingly the actual data will be uploaded only if the information is processed and found satisfactory, say the specified bit is set and the type of data (say audio) is as required. This is, of course, only an example and the information may include other content, all as required and appropriate depending upon the particular application.

0057Afterwards, the node evaluates the Segment Information received from the peers and schedules the fetching of the segments from the peers. By this example, after the evaluation of the peers acquired segments, the node decides to retrieve a certain segment (e.g. in a random manner) from 304A (indicated at <b>6</b>, <b>7</b>). Other segments may be retrieved from other peers. In a certain embodiment, a node may be connected to 10-20 other peers and fetch different media segments from all of them.

0058As explained above, the server receives periodic information and statistics regarding the channels/media transmission status and individual indication from the nodes (see, e.g. <figref idref="f0007">Figs. 4B</figref> and <figref idref="f0008">4C</figref> below). In case the server deduces that new amplifiers are needed in the swarm in order to maintain a good quality media transmission, the server may address a specific node (<b>8</b>) to the swarm and request its services by adding it to the swarm. This mechanism is described, in accordance with certain embodiments, in more detail below.

0059Note that the invention is not bound by the specific sequence of operation described with reference to <figref idref="f0006">Fig. 4A</figref>.

0060Before turning to <figref idref="f0009">Fig. 5</figref>, attention is drawn to <figref idref="f0007">Figs. 4B</figref> and <figref idref="f0008">4C</figref>, illustrating a sequence of operation of a server logic in accordance with an embodiment of the invention.

0061Thus, as shown in <figref idref="f0007">Fig. 4B</figref> in step 490 every certain amount of time or event that triggered the evaluation process, then in step 491 the server evaluates the media distribution status of the channel. The dynamic information module 492 will be described in further detail with reference to <figref idref="f0008">Fig. 4C</figref>.

0062Next, in step 493 is there a need to add bandwidth (BW), and if yes, in step 495 peers from the pool or from other swarms are chosen, otherwise, the sequence ends (494). Moving on with step 496, orders are sent to the peers to join the channel, and then 497, where a certain amount of time is waited.

0063Turning to <figref idref="f0008">Fig. 4C</figref>, (elaborating module 492 in <figref idref="f0007">Fig. 4B</figref>), in step 4001 the server gets statistical 'status' information from peers. The status includes: <ol id="ol0001" compact="compact" ol-style=""><li>a) Average uploaded bandwidth during the last few seconds</li><li>b) Average downloaded bandwidth during the last few seconds</li><li>c) Number of peers connected to the node and contributing data to it</li><li>d) Number of peers connected to the node and fetching data from it</li><li>e) Video quality (if a consumer)</li><li>f) Average frame Rate (if a consumer).</li></ol> Then in step 4002 the server analyzes if any of the parameters reaches a Red-Flag. Examples of Red-Flag are if not even one peer is connected to the node; the Video quality is below a certain flag; or there is a very low average frame rate, and if red flag is detected (4003) then in step 4007 more resources are needed, and subsequently an inquiry is made at 4008 which asks whether enough bootstrap AMPS in the channel is available, and if yes 4009 other peers with available resources are added, otherwise (no) in step 4010 bootstrap amps are added. Reverting to 4003, in the case of no, in step 4004 the server summarizes the parameters retrieved from peers, and thereafter 4005 the server analyzes if any of the sums reaches a 'sum' Red-Flag. Examples of this are whether the sum of upload BW is greater than the sum of download BW,and whether the average video quality in the channel is good enough. In step 4006 the Red-Flag is tested. In the case of no, 4011 no more resources are needed at this stage, otherwise (yes) the procedure described in steps 4007,4008, 4009 and 4010 is performed.

0064The invention is not bound by the specific examples described with reference to <figref idref="f0006 f0007 f0008">Fig. 4</figref> and <figref idref="f0008">4C</figref>.

0065Attention is now drawn to <figref idref="f0009">Figure 5</figref> illustrating a flow chart of the mechanism and parameters to add an amplifier to the swarm, in accordance with a certain embodiment of the invention.

0066<figref idref="f0009">Fig. 5</figref> deals with the control and management of the server of the clients that function as amplifiers. The problem this mechanism solves is the need to have sufficient bandwidth in the system to support the customer and the way to add amplifiers so that the bandwidth need is met and that newly joined consumers will have a fast and smooth entry to the system. In accordance with certain embodiments, the need for support in bandwidth is either triggered by a node suffering from lack of sufficient bandwidth or detected by a server who monitors the channel, see e.g. the architecture application and <figref idref="f0007">Figs. 4B</figref> and <figref idref="f0008">4C</figref>.

0067The process describes the steps and operations performed by the elements of the system, as well as the interaction between said elements including one or more nodes. In the first step of this process, the server is triggered (501) either by the 'swarm' namely from one of the nodes in the swarm by sending statistics, by sending a signal indicating a problem in the media delivery, by spending an indication about a problem in the number of peers the node sees, (see e.g. the architecture application and <figref idref="f0007">Figs. 4B</figref> and <figref idref="f0008">4C</figref>), or (502) by a timer indicating the need to evaluate the media transmission quality.

0068Afterwards, in (503), the server evaluates the channel status (the media delivery status). This is done by summing-up the entire information about the nodes in the channel. This information includes the roles of the nodes (amplifiers, bootstrap amplifiers, consumers), the bandwidth they download, the bandwidth they upload, the average video quality the consumers see, and the number of peers they have and the number of partners they work with. Other parameters may also affect this decision, (see e.g. the architecture application and <figref idref="f0007">Figs. 4B</figref> and <figref idref="f0008">4C</figref>), for instance whether the channel (the media) is being transmitted in a good enough quality.

0069The evaluation of the situation at (503) leads to the question whether the channel (the media) is being transmitted in a good enough quality or else additional Amplifiers should be added (504). The quality is calculated by combining the media quality (such as PSNR for video quality) and the 'streaming' quality calculated from several other parameters such as the percentage of received segments out of the ordered one, the number of partners each consumer has, and others (see e.g. <figref idref="f0008">Fig. 4C</figref>). In case the quality of the service is not sufficient, the server evaluates if the Amplifier to be added should be a Bootstrap Amplifier (discussed in greater detail below) that never shuts down or not (505) and decides what type of Amplifier to add (506, 507). According to certain embodiments, some channels may have a specific number of bootstrap amplifiers to guarantee a smooth operation of the channel. The server then waits and evaluates the situation again. In case the media is being distributed at a satisfactory level (e.g. if no more resources are needed, see 4011 at <figref idref="f0008">Fig. 4C</figref>, the process ends (509)).

0070The decision which amplifier to add is derived from an analysis of the list of amplifiers in the pool; amplifiers that send periodic information (see e.g. the architecture application and <figref idref="f0008">Fig. 4C</figref>), to the server regarding their status. The peers that the servers decided to support (by allocating amplifier(s) thereto) should contain the nodes with problems in the media distribution (see also <figref idref="f0012">Fig. 7</figref> of the architecture application). Note that in accordance with certain embodiments, there is no need to subtract amplifiers from the list due to the self shut-down algorithm which is part of the amplifier's logic and that causes the Amplifiers to shut themselves down when they do not contribute to the swarm. Note that the invention is not bound by the specific sequence of operations described with reference to <figref idref="f0009">Fig. 5</figref>.

0071Attention is now drawn to <figref idref="f0010">Figures 6A</figref>,<figref idref="f0011">6B,6C</figref> illustrating the amplifier's logic, in accordance with a certain embodiment of the invention.

0072The amplifier internal logic, in accordance with this embodiment, is based on the requirement to maximize the bandwidth taken from the amplifier while minimizing the bandwidth taken by it, or, to maximize the Amplifier's Gain (defined as upload bandwidth minus the download bandwidth). Evidentially, an amplifier with a negative gain consumes more than it supplies and thus has a negative impact on the network's overall bandwidth. The amplifiers' logic can be described generally as searching and reaching the maximum Gain by increasing and decreasing the downloaded bandwidth rate limit in small steps till the maximum Gain is reached.

0073This procedure is described in <figref idref="f0010">figures 6A</figref>, <figref idref="f0011">6B</figref>, and <figref idref="f0011">6C</figref>. <figref idref="f0010">Figure 6A</figref> describes the algorithm's flow; <figref idref="f0011">figures 6B and 6C</figref> depict an example to explain the algorithm, in accordance with this embodiment.

0074As shown, at 600A the Amplifier is up and starts to run. Then the amplifier adds to its original download-rate-limit 601A the value of Step and starts to download from the other peers in the swarm for a defined time at a rate of current downoad-rate-limit plus Step. The amplifier then evaluates the upload bandwidth and calculates the New Gain (602A- originally set to zero or to another value based on history or default). The amplifier then evaluates if the new Gain is better or worse than the previous one (603A) and changes the direction of the Step (604A) if the Gain wasn't increased (possibly multiplied by a certain value k). Thus, if the Gain has improved, the amplifier continues in the same direction (i.e. adding Step to its currently download rate limit- see 606A), otherwise the interval changes its sign and the amplifier sets the download-rate-limit less than before (604A or more if the interval was negative previously). Note the K>1 is used in accordance with certain embodiments, to increment more than one step in each iteration. By way of non-limiting example, at the onset k=1, if in each one of X consecutive iterations (X predefined) an increment in the download rate is made by a factor of step (without reversing direction - step 604A), then an increase in download rate can be made by a factor of k times step (k>1). If 604A is encountered, then k can be set again to 1.

0075This algorithm can be explained using the example depicted at 6B and 6C (values of 6C are presented graphically at 6B). In the example, the initial values of the download-rate-limit and the Gain are set to zero (iteration 0 in <figref idref="f0011">FIG. 6C</figref>); the Step is set to 50Kbits/sec. As in 601A, the download rate limit is increased to 50Kbits/sec and the upload value is calculated after a certain amount of time. As can be seen in 6C (Iteration 1) the upload value measured is of 70Kbits/sec, thus the Gain is 70-50=20Kbits/sec as shown on the graph at 6B as well. Due to the increase of the Gain (New Gain 20 is greater than Gain 0 [step 603A]) and the fact that the Gain is greater than zero, the Step is added to the download-rate-limit which is now set to 100Kbits/sec. The upload rate is now calculated again and, as seen at the table at 6C (Iteration 2), the value received is 40 Kbits/sec. Since the value 40 is again higher than the previous Gain 20, the Step is added to the download-rate-limit which is now set to 150 Kbits/sec. In the example 6B, 6C, the Gain increases till Interval 6 in which the Gain decreases from 120 Kbits/sec to 110 Kbits/sec. At this point the Step will change its direction (k=1 at 604A) and will go back to a download-rate-limit of 250 Kbits/sec. If the upload value received per each download-rate-limit remains constant, the amplifier will go up and down in the graph around the points 200-300Kbits/sec, maximizing its Gain.

0076Reverting to <figref idref="f0010">Fig. 6A</figref>, 607A and 608A describe the amplifier shutdown mechanism, in accordance with certain embodiments of the invention. The amplifier shuts down after going up and down for a few iterations (e.g. 5) and receiving a negative Gain time after time. Bootstrap amplifiers always remain up, so the shutdown counter in their case remains zero.

0077Note that the invention is not bound by the specific sequence of operation of <figref idref="f0010 f0011">Fig. 6</figref>.

0078In accordance with certain embodiments, in order to have a fast start-up for newly added consumers' nodes, the term of Bootstrap Amplifiers is introduced. Bootstrap amplifiers don't shut down themselves and 'work on void', even when there are no consumers in the swarm, assuming that they will need the upload bandwidth for news nodes. The reason for the bootstrap amplifiers can be explained using the following example: consider a broadcaster with available upload bandwidth of 1Mbit/sec and consider a consumer attached to it with 1Mbit/sec available download bandwidth but with only 250Kbits/sec upload. In such a case the consumer will use the total amount of bandwidth from the broadcaster and other joining consumers will have bandwidth of only 250Kbits/sec. However, if there are available, for example, 20 bootstrap amplifiers, with available upload bandwidth of 250Kbits/sec, the media can be divided into several pieces in such a way that the total upload bandwidth of the system will be of 20x250 = 5Mbits/sec, thus enabling 5 new joined consumers (each downloading 1Mbit/sec) to fetch a good quality media.

0079Attention is now drawn to <figref idref="f0012">Figure 7</figref> illustrating a flow diagram of the amplifier's scheduling parameters algorithm, in accordance with a certain embodiment of the invention.

0080The segments priority algorithm role is to prioritize the segments to be retrieved in terms of their importance. The importance of the segments is determined according to one or more of the following aspects: <ol id="ol0002" compact="compact" ol-style=""><li>1. The importance of the media segment to be retrieved (701), for example, type of segments. For instance, audio has priority over video, within video, the key frames ('I' frames in H.264) have priority over motion estimation frames (such as 'P' and 'B' frames in H.264). Accordingly, by this example, the amplifier will download an audio segment before a video segment.</li><li>2. The missing segments at the peers the amplifier serves (702). The amplifier, knowing the segments they have and have already requested (for instance according to the value of the bit indicating availability or not of media data, as described above in the context of information, will request other segments which are useful for them.</li><li>3. The rare segments in the network (703). In order to maintain the network in a wealthy situation, the amplifier retrieves the segment parts with the lowest distribution in the network. This is known as the rarest first algorithm in the Bittorrent protocol. More specifically, in the case that there is a segment which resides in very limited number nodes (rare segment), it would be prudent to increase the circulation of this rare segment (thereby rendering the network wealthy, by circulating the segment to more nodes), in order to anticipate a situation that this segment will be requested by many nodes, and now, having sufficient copies thereof spread in the network, the likelihood of having sufficient nodes that can upload the requested segment is considerably improved compared to the situation that only few nodes store the segment (whilst many request it), thereby unduly slowing down the downloading rate of media containing the specified segment.</li><li>4. In the present invention, the importance of the segments is determined according to the following aspect: taking segments that are Xored from actual media segments (704). While retrieving a segment from the peers, the Amplifier has to prioritize Xored segments. An example of this is illustrated in <figref idref="f0012">Fig. 8</figref>:</li></ol> Assume peer A has segments 1, 2 (801). Further assume peer B has only segment 1 and peer C only segment 2 and that the amplifier should now decide which segment to retrieve. Evidently if the Amplifier fetches the Xor value of segment 1 and 2 from node A (802) it can serve both B and C (B will construct segment 2 from segment 1 it has and the Xor(1,2) (803), C will construct segment 1 from segment 2 it has and the Xored segment (804)).

0081A system and method has been shown in the above embodiments for the effective implementation of amplifiers in a realtime peer-to-peer distribution of media. While various preferred embodiments have been shown and described, it will be understood that there is no intent to limit the invention by such disclosure, but rather, it is intended to cover all modifications and alternate constructions falling within the scope of the invention, as defined in the appended claims. For example, the present invention should not be limited by software/program, computing environment, specific computing hardware, number of nodes, number of media types, number of viewers, number of amplifiers, number of consumers, or number or type of client devices.

0082It will also be understood that the system according to the invention may be a suitably programmed computer. Likewise, the invention contemplates a computer program being readable by a computer for executing the method of the invention. The invention further contemplates a machine-readable memory tangibly embodying a program of instructions executable by the machine for executing the method of the invention.

0083The above enhancements and described functional elements are implemented in various computing environments. For example, the present invention may be implemented on a conventional IBM PC or equivalent, multi-nodal system (e.g., LAN) or networking system (e.g., Internet, WWW, wireless web). The programming of the present invention may be implemented by one of skill in the art of peer-to-peer networking, server based application, and protocol-based network communications programming.