Content storage and delivery systems and associated methods

Systems and methods are provided for the storage of content on a network and the delivery of content to subscriber locations. According to one system and method, content is delivered to a set-top box from a content source in the process of transmitting the same content to another set-top box. The content source instructs a shared router to duplicate the content such that the content is transmitted to the requesting set-top boxes substantially simultaneously. According to another system and method, a server and cache provide dynamic caching of content such that requests for content are satisfied from the cache if possible. If the requested content is not found in the cache, the content is requested from alternate source and added to the cache. Weight values associated with the stored files are updated such that the more frequently requested files are maintained in the cache.

BACKGROUND

The demand for access to shared content, such as video content, audio content, Internet web content, or interactive games, among other types of content, is ever increasing and becoming more challenging to meet. Subscribers to a content provider network are seeking access to larger files, are seeking this access more frequently, and are demanding that this access be faster, more reliable, and more cost effective.

The storage of content on a network and its distribution from a content provider to various subscribers of the network has traditionally been accomplished through a hierarchical client-server protocol, where a central server, such as a content library, stores content for sharing among the subscribers. For example, digital video content, such as movies and television broadcasts, may be stored in a content library that is accessible by equipment at the various subscriber locations. When a subscriber requests to see a certain movie, the subscriber's equipment, such as a set-top box, running the same communication protocol as the content library will communicate with the content library to download the requested movie to the subscriber location for viewing on a television or computer screen.

Certain types of content, such as digital video content, consist of large amounts of data. Such content requires more space for storage in the central content library and more time for downloading to the subscriber location. At times of heightened demand, for example when a new movie has been released to the content library and many subscribers desire to see the same movie at the same time, the system can be overwhelmed and unable to meet the demand. Some subscribers may be unable to access the content at all. Other subscribers who are able to access the content may experience longer download times or poor content quality. The consumption of bandwidth in traditional systems for distributing content to a subscriber may also adversely affect the speed and reliability of content distribution to other subscribers. Furthermore, as content is added to the content library, the storage capacity of the library must be increased to accommodate the growing volume of content. The larger content library may similarly impose upon subscribers the problems of slow downloads and poor content quality.

In order to improve the situation for subscribers, content providers have attempted to pre-distribute content closer to the subscribers. For example, smaller, intermediate content libraries may be formed and dedicated to the service of a smaller number of the total subscriber base. Popular content, such as newly released movies, may then be moved to the intermediate content libraries so that they are more easily accessible by the corresponding groups of subscribers. Although such pre-distribution of content does serve to improve the subscribers' access to the content, there are tremendous storage costs to the content provider associated with forming the various intermediate content libraries. There are also significant operational costs incurred by the content provider due to the requirement for personnel to engineer the content distribution on a regular basis. In other words, the content provider incurs significant costs in determining which content is in demand and where best to store the content.

Therefore, there is a need for a system to store content on a network and to deliver the content from a content provider to a subscriber in a manner that improves the location of the content with respect to the various subscribers, is highly resilient and meets customer expectations with regards to download speeds and content quality, reduces content library growth requirements, and effectively manages bandwidth consumption.

DETAILED DESCRIPTION

Exemplary embodiments now will be described hereinafter with reference to the accompanying drawings, in which exemplary embodiments and examples are shown. Like numbers refer to like elements throughout.

Systems and methods for storing and delivering content over a network as well as a set-top box for facilitating the storage and delivery of content are provided in accordance with various exemplary embodiments. In general, a network is described having a number of set-top boxes and a main content source, such as a content library. The content library and each subscriber set-top box are configured to operate according to a peer to peer file distribution protocol. The protocol is aware of the network topology, the accessibility of set-top boxes on the network, and cost metrics consisting of router hops and set-top box upstream bandwidth. The protocol uses this information to automatically select sources of content in a more efficient and cost-effective manner.

Referring toFIG. 1, embodiments of the system10comprise a first router12, a plurality of second routers14, and a plurality of subscriber set-top boxes16. Each subscriber set-top box16is connected to a main content source18via the routers through a communication pathway20, which may comprise, for example, copper cable, fiber optic cable, a wireless connection, or a combination of these and/or other communication links. The system may also comprise intermediate routers22,23disposed along the communication pathway20between the main content source18and the subscriber set-top boxes16. As such, a relatively hierarchical network is established between the main content source18and the subscriber set-top boxes16. Typically, the network is a packet-switching network with the subscriber set-top boxes16being configured to transmit and receive content over the network according to a peer to peer file distribution protocol.

InFIG. 1, content may be transmitted from the main content source18through the first router12to either or both intermediate routers22,23in parallel. While two intermediate routers22,23are depicted in the embodiment ofFIG. 1, a network typically includes many intermediate routers22,23with the first router12configured to control distribution of the content to a selected one or more of the intermediate routers22,23. The content may be digital, for example, and may include data such as video content, audio content, Internet web content, or interactive games. The first router12may be a video distribution router, for example, and the intermediate routers22,23may be gateway routers. In embodiments in which the portion of the network between the intermediate routers22,23and the subscribers consists of optical fibers, each branch of the communication pathway20inFIG. 1is configured to transmit content from the intermediate routers22,23to an optical line termination (OLT) unit24, either directly as shown or via additional intermediate routers22,23. The OLT unit24receives the content and converts the content to corresponding optical signals for transmission to the subscriber. More than one communication pathway20may extend from one intermediate router22,23, thereby allowing the connection of more than one OLT units24to one intermediate router22,23. Routers in communication with multiple subscriber set-top boxes16served by the respective router, such as intermediate router23inFIG. 1, act as hubs to coordinate communication among the respective subscriber set-top boxes16, as well as between each respective subscriber set-top box16and the main content source18.

Continuing along each communication pathway20, the fiber optic cable runs from the OLT unit24, through an access network26, such as a gigabit-capable passive optical network, towards the subscriber set-top boxes16. Each set-top box16is associated with a second router14and an optical network termination (ONT) unit28. The ONT unit28converts the content, which may be in the form of an optical signal, to a format that is compatible with the subscriber set-top box16, such as corresponding electrical signals. The second router14may be a broadband home router, for example, and may be capable of receiving the content from the ONT unit28and transmitting the content to the associated set-top box16for eventual display on a television, computer, or other peripheral32to which the set-top box16is connected.

The main content source18is configured to store content that may be accessed and copied, e.g., downloaded, by the various subscriber set-top boxes16through the associated communication pathways20. For example, the main content source18may be a server such as a content library holding video content to be transmitted on demand to the subscriber set-top boxes16. When a subscriber at location A wishes to access certain content, for example a movie, from the content provider, a query is transmitted using to a peer to peer file distribution protocol from the subscriber set-top box16at A to the closest hub along the communication pathway20, which inFIG. 1would be intermediate router23.

Unlike prior approaches in which the query would have always been directed to and serviced by the main content source18, exemplary embodiments of the system10and method initially attempt to access the requested content from other subscriber set-top boxes16served by the same hub which had previously downloaded and stored the requested content. As such, intermediate router23inFIG. 1routes the query to other set-top boxes16connected to the same hub router23, or in this case B and C. If a queried set-top box16has the requested content, the queried set-top box16will transmit data back to the requesting set-top box16at A. The data transmitted may include identifying information, such as the network address of the queried set-top box16, as well as other descriptive data, such as the physical location of the queried set-top box16and the associated data transmission rate or bandwidth. Each subscriber set-top box16therefore includes a storage area30, e.g., memory, such as a disk, for storing such data as well as for storing content downloaded by the set-top box16. Information in the set-top box16may be updated periodically by the content provider, for example once a day or once a week, to include new subscriber set-top boxes16added to the network and the removal of subscriber set-top boxes16from the network. Information for new set-top boxes may include the IP address, the location in the network topology, and upstream bandwidth.

If no queried set-top box16has the content requested, the query will be transmitted to the next available upstream (i.e., closer to the main content source18in terms of network topology) hub or router. This next available upstream hub relays the query to the subscriber set-top boxes16serviced by the hub and relays any responses from the set-top boxes16to the set-top box16that made the initial query. If no queried set-top box16can provide the requested content, this process continues with more upstream hubs canvassing increasingly larger subsets of set-top boxes16until the query reaches the first router12associated with the main content source18. For example, if the query transmitted by A is not satisfied by B or C in the embodiment ofFIG. 1, the query will be forwarded to the first router12. In one embodiment, the first router12not only determines that the requested content can be provided by the main content source18, but also transmits the query to the other set-top boxes16connected thereto and relays any responses to the set-top box16that made the initial query. Thus, if none of the subscriber set-top boxes16that are queried along the pathway20have the requested content, the requesting set-top box16may access the content from the set-top box16at D or the main content source18.

The content provider may decide to route the query directly back to the content source18at its discretion instead of directing it down another branch of the network hierarchy for operational reasons. An example of an operational reason may be that the network cost of reaching the main content source18is less than the network cost of reaching a group of set-top boxes16. Another operational reason may be that the content provider determines that a particular section of the network is more congested than the communication pathway20leading to the main content source18.

Alternatively, the requesting set-top box16may broadcast the query to all set-top boxes16in the area capable of receiving the query. This may include set-top boxes16served by the same hub as the requesting set-top box16as well as set-top boxes served by upstream hubs. In the case where the query is broadcast to all set-top boxes16in the area, the requesting set-top box16may initially receive responses from only some of set-top boxes16, such as the set-top boxes16that are closer than other set-top boxes16in terms of network topology to the requesting set-top box16. If the requesting set-top box16is able to obtain the predetermined content from the first responding set-top boxes16, i.e., the closer set-top boxes16, then any subsequent responses received from other set-top boxes16having the predetermined content may be ignored by the requesting set-top box16.

Once the requesting set-top box16has accessed the requested content, from whatever source, a copy of the content is stored in the respective storage area30. In one embodiment, the storage area30is partitioned, either physically or logically, into at least two partitions34,36, at least one of which is accessible by the content provider. The partition36accessible by the content provider may be designated for the sole use of the content provider and secured against access by anyone else, including the associated subscriber, resulting in exclusive access of the partition36by the content provider.

The copy of the content accessed may be stored in the partition36of the storage area30accessible by the content provider. In this way, when a future query is received from a remote set-top box16, for example the set-top box16at C, the content stored in the partition36of the storage area30accessible by the content provider (at A) will be referenced, and content satisfying the query may be copied or streamed from the partition36of the storage area30accessible to the content provider of the queried set-top box16(A) to the partition36of the storage area30accessible to the content provider of the requesting set-top box16(C). The subscriber set-top boxes16may be designed to automatically delete content in the designated partition36of the storage area30after a certain amount of time has passed. For example, the partition36of the storage area30accessible to the content provider may be cleared every24hours to allow space in the storage area30for the storage of newer content.

The subscriber set-top box16may be configured to determine the preferred source of the requested content. For example, the requesting set-top box16at A may determine which of the queried set-top boxes16at B and C having the requested content is geographically closest to the location of the requesting set-top box16(A) based on the identifying data transmitted from each of the queried set-top boxes16(B and C) to the requesting set-top box16(A). Alternatively, the requesting set-top box16at A may determine which of the queried set-top boxes16having the requested content is the closest in terms of Internet Protocol (IP) network location to the requesting set-top box16(A). For example, referring toFIG. 1, if both the set-top boxes16at B and D were queried by the set-top box16at A, the requesting set-top box16at A would determine that B is closer in terms of IP network distance than D because content from D would have to make three router hops (22,12,23) whereas content from B would only have to make one router hop (23) to reach A. As this example indicates, closeness in terms of IP network location may be determined based on the number of routers required to relay the content to the requesting set-top box16.

The requesting set-top box16(A) may be configured to analyze the data transmission rate, for example the bandwidth, associated with each of the queried set-top boxes16(B and C) having the requested content to determine which set-top box16would provide the fastest and most reliable connection. The subscriber set-top boxes16may also be configured to determine the preferred source of the requested content in other manners, if so desired. By accessing the content from a preferred source, the efficiency of the download process may be relatively high. For example, accessing the content from a relatively near set-top box16as opposed to a relatively distant main content source18may reduce the time required to download the file and may reduce the transmission load carried by at least certain portions of the network.

The content stored in the main content source18and in the storage area30of the various set-top boxes16may be fragmented such that the fragments of data, which when combined form a complete file, may be obtained from different locations. For example, digital video content associated with a movie file may be fragmented into smaller files that, together, comprise the whole movie file, the fragments being similar to “chapters” of a movie on Digital Video Disc (DVD). Each fragment may be accessible independently of other fragments of the same file by the requesting set-top box16such that if, for example, one of the fragments of a file accessed from a preferred source is missing, damaged, or otherwise inaccessible, the requesting set-top box16may access that missing fragment from an alternate source, thereby achieving access to a complete file. By obtaining most, or, at least, as much as possible, of the file from the preferred source, the overall efficiency of the downloading process is still relatively high, even though one or more fragments had to be retrieved from a less preferred source. Alternatively, the requesting set-top box16may determine multiple preferred sources. In the case of multiple preferred sources, the efficiency of the downloading process may be increased, and the load on the network may be decreased, by obtaining fragments of the complete file from each preferred source at approximately the same time.

Embodiments of the system10described above are not limited to the configuration shown inFIG. 1. The network extending from the content provider to the various subscribers may be designed to meet the demands of a predetermined number of subscribers covering a predetermined geographical region, as dictated by the speed of data transmittal over the communication pathways, the volume of subscriber demands, and the size of the main content source18. The network may be expanded by connecting more than one main content source18,18′, each additional main content source18′ supporting its own content-sharing network, such that subscriber set-top boxes16associated with one main content source18may communicate with other main content sources18′ and with set-top boxes16′ associated with those other main content sources18′ via the first routers12,12′ associated with the main content sources18,18′.

Regardless of the source of the content, whether it be a set-top box16or the main content source18, in some embodiments a system is provided for distributing the same content substantially simultaneously (i.e., simultaneously or nearly simultaneously) to two or more requesting set-top boxes16. A first content source, which may be a main content source18or another set-top box16, is configured to interface with a communications network, to receive requests for content from set-top boxes16, and to request content from alternate content sources, such as other set-top boxes16connected to the communications network. A router, such as an intermediate router22,23or first router12, may be configured to communicate with the first content source, the alternate content sources, and the set-top boxes. The first content source may be configured such that if the first content source receives a request for the same content initially from a first set-top box and then subsequently from a second set-top box while the first content source is transmitting the requested content to the first set-top box16via the router, the first content source instructs the router to duplicate the content. In this way, the content is transmitted to both the first and second set-top boxes substantially simultaneously.

For example, referring again toFIG. 1, set-top box B may request content, such as Great Movie, and may begin receiving a transmission satisfying the request from set-top box A, which may happen to have the particular movie stored in the partition36of the storage area30accessible by the content provider, as previously discussed. As set-top box A is distributing content to set-top box B, set-top box A may receive a second request for Great Movie from set-top box C. Instead of waiting to satisfy the request from set-top box C until after the transmission to set-top box B is complete or declining to satisfy the request from C, set-top box A may be configured to instruct the intermediate router23, via which the content is being transmitted to set-top box B, to duplicate the content such that the content is substantially simultaneously transmitted to both set-top boxes B and C. For example, the first content source (A in this example) may be configured to multicast the content to the first and second set-top boxes (B and C). In this way, bandwidth corresponding to the portion of the communication pathway20between set-top box A and the intermediate router23may be conserved because set-top box A is already transmitting Great Movie to set-top box B, and no additional bandwidth is required along that portion of the pathway to satisfy C's request. Furthermore, because the content is substantially simultaneously sent to both C and B, satisfaction of set-top box C's request may not be delayed as a result of the transmission to B.

It is to be understood that in the previous example the intermediate router23, as opposed to other routers, may be instructed to duplicate the content because the intermediate router23is the closest shared router to the requesting set-top boxes. For example, if the content were instead provided by set-top box D via the intermediate router22, the first router12, and the intermediate router23, set-top box D would generally instruct the intermediate router23to duplicate the content as the intermediate router23would be the closest shared router, in terms of network topology, to the two requesting set-top boxes (B and C). In this way, the greatest amount of bandwidth may be conserved by permitting common transmission for the longest distance.

In some cases, the first content source may be configured to instruct the router to transmit a first portion of the content to the second set-top box16starting at a content boundary corresponding to the point during transmission of the content to the first set-top box at which the request from the second set-top box was received. For example, although set-top box C may request the same content that A is transmitting to B, the request from C may be received after A starts transmitting the content to B. In this case, rather than instructing the router to duplicate the content (and thus begin transmitting the content to C) immediately upon receipt of the request for the same content, A may be configured to instruct the router to transmit a portion of the content starting at a predefined content boundary. For instance, if the content (Great Movie) is a movie having 24 chapters and the request from C is received while A is in the process of transmitting chapter 3 to B (the original requesting set-top box), set-top box A may instruct the router to duplicate the content such that C begins receiving the content starting with chapter 4 (i.e., starting at the content boundary between chapters 3 and 4). Thus, in this example, set-top box C would receive a first portion of the content that includes chapters 4-24. The first content source A may then provide a second portion of the content, chapters 1-3, to set-top box C to complete the transmission.

In some cases, the first content source (set-top box A in the previous example) may also be configured to request the second portion of the content, corresponding to a part of the content transmitted to the first set-top box before the request from the second set-top box was received, from at least one of the alternate content sources. Continuing the previous example, set-top box A may request chapters 1-3, the three chapters that had been transmitted or were in the process of being transmitted to set-top box B when the request for content was received from C, from an alternate content source. For example, the main content source18may act as the alternate content source, providing the missing three chapters to set-top box C, or set-top box B (which has just received the content from A) may act as the alternate content source. If an alternate content source is not found, or if requesting the second portion (e.g., chapters 1-3) from the alternate content source is deemed to involve an unacceptable network cost, then the first content source (A) may transmit the second portion as soon as it is able to do so (e.g., after completing transmission of the first portion to both B and C). Additionally, the second portion may be requested from multiple alternate content sources. For example, the main content source18may provide chapter 1, and set-top box B may provide chapters 2 and 3.

In cases in which the second set-top box may receive portions of the requested content from multiple sources, i.e., the first content source and one or more alternate sources, the second set-top box may be configured to assemble the first and second portions of the content into a complete content file. For example, set-top box C in the previous example, after receiving chapters 4-24 from set-top box A and then receiving chapters 1-3 from the main content source18, may be configured to assemble the two portions into a complete content file, Great Movie, such that a user of set-top box C may be able to view Great Movie in a logical order, starting with chapter 1 and ending with chapter 24.

In other embodiments, a system for distributing content is provided including a number of set-top boxes16configured to interface with a communications network, at least one content source configured to receive requests for content and transmit content, a router configured to forward the requested content toward a requesting set-top box, and a server.FIG. 2shows a communications network, such as the network ofFIG. 1, that is simplified for the purposes of explanation (i.e., not all network components represented inFIG. 1are illustrated). Referring toFIG. 2, the content source may be a main content source18or any other source that is capable of transmitting the requested content to the requesting set-top box, such as another set-top box16. The router may be any router via which content is transmitted from the content source and the requesting set-top box16, such as intermediate router23inFIG. 2or any other router between the content source and the requesting set-top box (in terms of network topology). The router, such as intermediate router23, may be associated with or otherwise in communication with a server170, which is configured to receive a request for content from the requesting set-top box16and to receive and transmit content via the router.

The server170may be any computing device, such as a device that includes a processing element (e.g., a computer or computer system). The server170includes a cache172configured to store content and having a predefined capacity. The server170manages the cache172as a dynamic cache for storing content. Thus, the system11is configured such that when a request for content made by a requesting set-top box16is to be satisfied by the server170(according to the network rules and policies, such as proximity and bandwidth availability previously discussed), the server170is configured to satisfy the request from the cache172, if possible, and to update the cache172accordingly, as will be described below. For example, if the requested content is in the cache172, the server170is configured to access the requested content from the cache172and to transmit a copy of the content via the router to the requesting set-top box. If the requested content is not in the cache, the server170is configured to request the content from a content source, to store a copy of the content in the cache172, and to transmit a copy of the content to the requesting set-top box. The server170and cache172may thus be configured to store and maintain only certain content, such as the content that is most frequently requested and transmitted by or through the server170or the associated router (e.g., the intermediate router23).

The server170may be configured to delete previously stored content from the cache172if the storage of requested content would exceed the predefined capacity of the cache172. For example, if the cache172has 1 kb of memory remaining available for the storage of new content and the latest requested content (which is not currently found in the cache172and is thus to be added to the cache172once it is requested and received from a content source) requires 3 kb of memory, the server170may be configured to delete some of the previously stored content from the cache172to make the required amount of memory available. Thus, in this example, the server170may delete content utilizing at least 2 kb from the cache172such that 3 kb or more of memory are made available for the storage of the requested content.

In some cases, the server170may be configured to assign a weight value to the content when the content is stored in the cache172. The server170may also be configured to adjust each assigned weight value of previously stored content when new content is stored in the cache172and when the previously stored content is accessed from the cache172. For nomenclature, let fibe a particular content file belonging to set F, the set of all content files. Let wibe the weight value associated with file fi. For example, as requested content f1is stored in the cache172, the server170may assign the content a weight value w1of 1. Subsequently, when another item of requested content f2(not found in the cache172) is added to the cache172, the server170may assign f2a weight value w2of 1 and may update w1(the weight value of the previously stored content f1). Similarly, if previously stored content f3is accessed from the cache, the server170may adjust each weight value of the previously stored content (i.e., w1, w2, w3, etc.).

For example, the server170may reduce each weight value of the previously stored content if new content (i.e., content that is not currently in the cache, but not necessarily content that has never been stored in the cache) is stored in the cache172, and the server170may increase the weight value of the previously stored content if the previously stored content is accessed from the cache. In this way, greater weight values wimay reflect more frequently requested content (i.e., more popular content or content that is in demand), and lesser weight values wimay reflect less frequently requested content. The server170may be configured to select the previously stored content, in other words, one or more of the files stored in the cache, to delete according to the assigned weight value. Thus, the server may dynamically cache content files in the cache in such a way that only the more frequently requested files (as indicated by the weight values wiassociated with file fifor each of the files in the cache) are maintained in the cache.

Such adjustments of the weight values w of previously stored content may be linear or non-linear. For example, in one exemplary embodiment using a linear adjustment, requested content may be assigned a weight value wrof 1 when it is stored in the cache172, as previously mentioned, and previously stored content may be adjusted according to the algorithm wi=wi−(1/n), where wiis the weight value of an item of previously stored content (i.e., i is not equal to r) and n is the number of files stored in the cache172. Thus, using this algorithm, if 100 files are stored in the cache at the time requested content is to be added to the cache, the requested content would receive a weight value wrof 1, and each of the hundred files currently in the cache (i.e., previously stored) would have its weight value wireduced by 0.01 (wi=wi−( 1/100)). As another example, a non-linear approach to adjusting the weight values wiassociated with a content file fimay be defined according to the algorithm wi=ln(xi), where xr=1 for the requested content file and xi=xi+1 for all other files, xibeing a counter associated with each file fi.

In other embodiments, a method of accessing content is provided. Referring toFIG. 3, embodiments of the method for accessing content initially query content sources for predetermined content, determine a preferred source of the content, obtain a copy of the content, store the content in a storage area30at the subscriber location, and, in turn, allow a plurality of remote subscribers to access content stored in the storage area30of the corresponding subscriber location. SeeFIG. 3, blocks100-108.

For example, a subscriber desiring to see a movie offered by a content provider may transmit a query for the associated video content through the subscriber's set-top box16. The query may be transmitted to other set-top boxes16connected on the network as well as to other potential content sources, such as a main content source18, in accordance with the hierarchical distribution techniques described above to identify sources that have the queried content. See block100.

Of the potential content sources identified, a preferred source of the content is determined, as shown in block102. Various types of preferences may be used to determine a preferred source of content, as illustrated in blocks116-122. The preferred source may be determined, for example, according to an algorithm implemented by the set-top box16which factors in the geographic distance between each potential content source and the subscriber location and chooses the source associated with the shortest distance. Similarly, the preferred source may be determined according to the Internet Protocol (IP) distance between each potential source and the requesting set-top box16, the algorithm choosing the source associated with the shortest IP distance. The preferred source may also be determined according to the bandwidth of the potential sources. For example, an algorithm implemented by the set-top box16may determine, at the subscriber location, the available bandwidth for each potential source and may then choose the source associated with the largest bandwidth. The selection of a preferred source of content may also be made using a composite function built from any combination of these factors or other factors not mentioned here.

Once a preferred source, as shown in block102, is determined, a copy of the requested content is obtained at the subscriber location. See block104. For example, a copy of the movie file may be downloaded from the preferred source to the subscriber's set-top box16. Some embodiments of the method may additionally include the evaluation of the content accessed, typically after the content is downloaded by the requesting set-top box16. See block110. The requesting set-top box16, for example, may evaluate the downloaded content against a predetermined standard and determine that there is an error. See block111. In general, an error may be caused by the transmission process or by the source. See block113. For example, the requesting set-top box16may receive less than a complete file, or a portion or all of the file received may be unusable as the result of an error in transmission. Similarly, a predetermined amount of time allowed for the downloading of the file from the preferred source to the subscriber location, such as one minute, may be exceeded. As a result, the requesting set-top box16may make another attempt to download the content. See block104.

If the error reflects a problem with the source of the content, i.e., the preferred source, an alternate preferred source may be determined and the content obtained from the alternate preferred source. For example, if several attempts to download the content from the original preferred source fail, then the unacceptable content may be aborted. Similarly, if the content is illegitimate, e.g., impermissibly copied, or if the file is unusable because some or all of the data contained therein is corrupt, then the unacceptable content may be aborted. The preferred source may then be abandoned and an alternate preferred source determined. See blocks112-114.

In the case that the preferred source is abandoned and an alternate preferred source is determined, the alternate preferred source may be the source that is, of the remaining potential sources, the most preferred based on the algorithm implemented by the set-top box16. For example, if the algorithm considered IP network distance as described above, then the alternate preferred source may be the source that is, of the remaining potential source, the closest in terms of network topology to the requesting set-top box16. It is noted that the operations shown in blocks110-114are optional and need not be performed in all instances. If operations110-114are not performed, the output of block104would generally be provided directly to operation106.

As shown in block106, the copy of the content successfully downloaded by the requesting set-top box16is then stored in a storage area30at the subscriber location, for example in the partition36of the subscriber's set-top box16accessible to the content provider. The subscriber may then be able to use the content, such as by viewing a movie on a television32connected to the subscriber's set-top box16. For example, the content that is downloaded by the requesting set-top box16, such as a movie, may be stored on a video serving domain disk or a virtual disk prior to being streamed to a television32for viewing or prior to being stored to the partition34accessible to the associated subscriber, such as the subscriber's disk or virtual disk.

Finally, remote subscribers querying the same content are allowed access to the content now stored at the subscriber location. See block108. For example, another subscriber desiring to see the same movie that a subscriber on the network has previously queried, obtained, and stored in the storage area30may be able to query for and then access the movie file as stored in the storage area30of the previous subscriber's set-top box16. Content stored at a subscriber location, however, may be deleted periodically, as shown in block124. For example, the set-top box16may be configured to delete content stored in the partition36accessible to the content provider after a predetermined length of time, such as 24 hours.

The content accessed according to embodiments of the method may comprise complete files, such as a movie in its entirety, or fragments of a complete file, such as “chapters” of a movie. Thus, according to one embodiment, fragments of a complete file may be independently queried, a preferred source for each fragment determined, and various fragments obtained from different sources. The various fragments would be assembled into a complete content file and stored at the subscriber location, however, such that the subscriber may use the content in its entirety, for example by viewing a movie from beginning to end.

For example, content may be accessed according to an exemplary embodiment illustrated inFIG. 4. In the exemplary embodiment, a subscriber selects content for viewing or for storage in the storage area30of the subscriber's set-top box16. A content location request is then broadcast to all content sources within the subscriber's video serving area, i.e., the set-top boxes16connected to the network within the subscriber's video serving area. If the requesting set-top box16does not receive any positive responses, which would indicate that none of the connected set-top boxes16in the area have the requested content, the requesting set-top box16downloads the content from the main content source18. SeeFIG. 4, blocks126-129.

If the requesting set-top box16receives positive responses to its content location request, the requesting set-top box16executes an algorithm based on a combination of the available bandwidth between each potential content source and the requesting set-top box16and the IP proximity of each potential content source to the requesting set-top box16. See blocks131-132. Based on the algorithm executed by the requesting set-top box16, a preferred content source is determined.

If the requesting set-top box16determines more than one preferred content source, the set-top box16requests portions of the content from each of the multiple preferred content sources. See block134. For example, if a movie having 24 chapters of content is requested and the requesting set-top box determines 4 preferred content sources based on the algorithm, the requesting set-top box16may request chapters 1-6 from the first preferred source, chapters 7-12 from the second preferred source, chapters 13-18 from the third preferred source, and chapters 19-24 from the fourth preferred source. In this way, the time required for transmitting the four smaller files (which may be, for example, a quarter of the size of the complete file) at approximately the same time from the four preferred content sources to the requesting set-top box16may be less than the time that would have been required for transmitting the one complete file from one of the preferred sources, thereby increasing the speed of the download. Alternatively, if only one preferred content source is determined by the requesting set-top box16, the complete file is requested and downloaded from the one preferred content source, as shown in block135.

In the exemplary embodiment ofFIG. 4, the content downloaded is then validated by the requesting set-top box16. See block136. For example, the content may be scanned by the requesting set-top box16to verify that the content is legitimate and/or that the content does not contain more than an acceptable amount of error. If the content is not acceptable, the requesting set-top box seeks to download the content (or the portion of content if the content was obtained from multiple preferred content sources) from a different preferred content source. For example, if one of the four preferred content sources in the previous example transmitted chapters 7-12 of the requested movie, but the content file was determined by the requesting set-top box16to be illegitimate, the requesting set-top box16may request chapters 7 and 8 from the first preferred content source, chapters 9 and 10 from the third preferred content source, and chapters 11 and 12 from the fourth preferred content source, thus bypassing the source of the illegitimate content. If, on the other hand, the requesting set-top box16determines that there was an error in the transmission of the content from one of the preferred content sources, then the requesting set-top box16may attempt to download the content again from the same content source. If after a predetermined number of attempts the transmission is still unsuccessful, the requesting set-top box16may turn to an alternate source, as previously mentioned.

Similarly, if content downloaded from the main content source18is determined to be invalid, the requesting set-top box16requests the content again from the main content source18. See block130. If, however, after a predetermined number of attempts the requesting set-top box16is unable to download acceptable content, the requesting set-top box may cease the attempts and may report an error to the subscriber.

If the content is determined by the requesting set-top box16to be valid, the requesting set-top box16then assembles the content files (if portions of the complete file were obtained from different preferred sources) and stores the content in the partition36of the storage area30that is accessible to the content provider. For example, the content may be stored on a video serving domain disk or virtual disk. The content may then be streamed to the subscriber's television for viewing by the subscriber and/or stored to the partition34of the storage area30that is accessible to the subscriber, such as the subscriber disk or virtual disk in the subscriber set-top box16. See blocks137and138. Content stored in the partition36accessible by the content provider may be erased after a set time period, such as 24 hours. See block139. However, content that has been transferred to the subscriber-accessible partition34may be available for use by the subscriber even after the content has been erased from the partition36.

Another method of distributing content is shown inFIG. 5. Content is transmitted from a content source, such as a main content source or a set-top box as previously described, to a first requesting set-top box via a router. A request for the same content is then received at the content source from a second set-top box, and the router is instructed to duplicate the content such that the content is transmitted to both the first and second set-top boxes substantially simultaneously. SeeFIG. 5, blocks200-204. For example, the router may be instructed to multicast the content to the first and second set-top boxes. As discussed previously, by initially combining the transmission of the content to both requesting set-top boxes and duplicating the content at the router, bandwidth along at least a portion of the communication pathway is conserved.

As the content source may already be in the process of transmitting content to the first requesting set-top box when the request is received from the second requesting set-top box, the router may be instructed to transmit a first portion of the content to the second set-top box starting at a content boundary corresponding to the point during transmission of the content to the first set-top box at which the request from the second set-top box was received. For example, content boundaries may include the boundaries between “chapters” of a movie, such that if a request for a movie was received from the second set-top box during transmission of the fifth chapter of the requested movie, the router may be instructed to begin duplicating the content and splitting the transmission starting with the sixth chapter. Thus, in this example, the two requesting set-top boxes would receive chapters 6 and on substantially simultaneously.

In the previous example, the second requesting set-top box may have missed the transmission of the first five chapters of the requested movie. See block206. In this case, a second portion of the content, corresponding to a part of the content transmitted to the first set-top box before the request from the second set-top box was received, may be requested from an alternate content source, such as from another set-top box or other content source. Block208.

In other embodiments, a method of distributing content via a system that includes a dynamic cache is provided. A request for content from a requesting set-top box is received at a server, and a determination is made at the server on whether the requested content is stored in a cache of the server. SeeFIG. 6, blocks216and218. If the requested content is in the cache, a copy of the content is transmitted from the cache to the requesting set-top box. Block220. If the content is not in the cache, the content is requested from a content source (such as another set-top box or a main content source), a copy of the content is stored in the cache, and a copy of the content is transmitted to the requesting set-top box. See blocks222,224, and220. AlthoughFIG. 6shows a copy of the content being transmitted to the requesting set-top box after it has been stored in the cache, in some embodiments the content may be transmitted to the requesting set-top box before it is stored.

As previously discussed, if storage of the requested content would exceed a predefined capacity of the cache, previously stored content (i.e., content that is currently in the cache) may be deleted, for example in order to make enough memory available for the storage of the latest content to be stored. See blocks226,228. The content to be deleted from the cache may be selected according a weight value associated with each content file. Thus, in some embodiments, a weight value may be assigned to the content when the content is stored in the cache. Block230. In addition, each assigned weight value of previously stored content may be adjusted when the requested content is stored in the cache and when the previously stored content is accessed from the cache. For example, as shown in block232, the weight values may be adjusted when a copy of the requested content is transmitted to the requesting set-top box (e.g., immediately before or after the transmission).

For example, a weight value of 1 may be assigned to the requested content that is stored in the cache. Furthermore, the weight values of the previously stored content may be adjusted by reducing each weight value of the previously stored content if the requested content is stored in the cache (i.e., added to the content already stored in the cache) and by increasing the weight values of the previously stored content if the previously stored content is accessed from the cache.

The weight values of previously stored content may be adjusted linearly or non-linearly. For example, a linear algorithm for adjusting the weight values is incorporated in the exemplary embodiment shown inFIG. 7. According to this exemplary embodiment, a request is received for a content file fr. SeeFIG. 7, block250. If fris one of the files in the set of files F already stored in the cache such that fris an element of F, then frmay be uploaded from the cache and the weights wiof the files F may be adjusted. The weight of the requested file frmay be adjusted to equal 1 (wr=1), and the weight values wiof the other files may be adjusted according to the linear algorithm wi=wi−(1/n), where n is the number of files in F. See blocks252-254.

According to the exemplary embodiment shown inFIG. 7, if the requested file fris not an element of F, a determination may be made on whether the sum of the files in F (Σ fi) plus the requested file fris less than or equal to the capacity C of the cache. Block256. If the addition of the file is not within the capacity C, then a file fkmay be selected such that the weight value wkof the file is the lowest among the weight values {wi} associated with the previously stored files. The selected file fkmay then be removed from the set of files F stored in the cache, and the associated weight value wkmay likewise be removed from the corresponding set of weight values W. See block258. If the removal of the file fkis not sufficient, and the capacity C would still be exceeded by the storage of the requested file fr, another file may be selected for deletion according to the same process until storage of the requested file is within the capacity C.

Once enough files have been deleted such that storage of the requested file is within the capacity of the cache, the requested file may be uploaded from the content source and copied to the cache. In addition, the set of files F may be adjusted to include the requested file fr(F would equal the union of F with fr), and the weight values would likewise be assigned and adjusted, as previously discussed and as shown in block260.

A set-top box16is also provided according to some embodiments, shown inFIG. 8. The set-top box16comprises an interface150configured to engage a packet-switching network162, such as the Internet, a storage area30, and a receiver and decoder152. The storage area30is partitioned into at least two partitions34,36, with at least one of those partitions36being accessible by a content provider. The receiver and decoder152is configured to receive digital content from a source or deliver digital content to a digital-ready device, such as a main content source18or a different subscriber set-top box16, store the content in the partition36of the storage area30that is accessible by the content provider, and convert the digital content for display on a peripheral device32such as a television.

The set-top box16allows other remote set-top boxes16to which it is connected to access the partition36of the storage area30that is designated for the use of the content provider. In this way, remote set-top boxes16may copy content from the storage area30of the set-top box16, and vice versa. One of many possible system10configurations is shown inFIG. 1. The set-top box16may be in communication with other set-top boxes16or main content source18using a communications protocol such as, but not limited to, peer to peer protocols such as BitTorrent. In addition, the set-top box16may be in communication with network elements such as routers connected to the network, such as a first router12, a second router14, an intermediate router22,23, or more than one of these in series, as shown inFIG. 1, where the connected routers enforce policy that may determine to which segments of the network queries for content sources may be routed.

In some embodiments, the set-top box16may further comprise a processor158, such as a microprocessor, a controller, or other computing device, for performing or at least directing the various functions of the set-top box16described above. For example, the process may determine a preferred source of the digital content. The processor158may determine the preferred source based on the bandwidth of the source, the distance between the source and the set-top box16, or other preferences. For example, the processor158may use an algorithm to analyze the IP network distance between the set-top box16and each potential source, then determine the source associated with the shortest distance, as described above. Typically, the process operates under the control of software for performing each of the functions subscribed to the set-top box16. This software may also be stored by the storage area30or by another associated memory device.

In the preceding specification, various embodiments of the claimed invention have been described. It will, however, be evident that various modifications and changes may be made thereunto without departing from the broader spirit and scope of the invention as set forth in the claims that follow. The specification and drawings are accordingly to be regarded in an illustrative rather than restrictive sense.