US20050188415A1 - Video policy server - Google Patents

Abstract

A system for distributing digital content includes two or more digital content sources. Each source has a separate session manager that is distinct from other session managers associated with other digital content sources. The system further includes at least one set of network resources that receive digital content from the two or more digital content sources, modulate the digital content onto a carrier signal suitable for transmission over an access network, and transmit the carrier signal over the access network. The system also includes a receiving device for terminating the carrier signal. The receiving device generates a digital content stream corresponding to the digital content from the two or more digital content sources. The system further includes a policy server for allocating bandwidth of the network resources to the digital content sources, and for monitoring a utilization state of the network resources.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
• This application claims benefit of the following U.S. Provisional Patent Applications:
• • “VIDEO POLICY SERVER,” U.S. Provisional Patent Application Ser. No. 60/538,803; filed Jan. 23, 2004 and,
  • “POLICY BASED ADMISSION CONTROL,” U.S. Provisional Patent Application Ser. No. 60/538,802, filed Jan. 23, 2004.
BACKGROUND OF THE INVENTION
• The present invention relates to content distribution over a network, and more particularly, to managing distribution resources for video-on-demand (VOD) and other content services on a cable network.
• Video-on-demand, one of several services offered by cable multiple system operators (MSOs), enables a subscriber to customize cable content according to their preferences and/or schedules. A typicalVOD distribution architecture10, shown inFIG. 1, includes aVOD server12 and asession manager14, a number of edge quadrature amplitude modulation (QAM)interfacing devices16, acable access network18, and a set top box (STB)20.
• TheVOD server12 hosts a large volume of digital video content. Portions of this content may be selected via a request from the subscriber. (i.e., the end user). Thesession manager14 is responsible for setting up a video session, i.e., processing requests from the subscriber and providing an interface between theVOD server12 and the other components in thedistribution architecture10. TheVOD server12 and the session manager13 are typically tightly coupled and sold as a set.
• The edge QAM interfacing devices (edge QAM)16 receive digital video content from thesession manager14, QAM-modulate and up-convert the content, then transmit resulting QAM signal onto the coaxial infrastructures within theaccess network18.
• The STB20 terminates the QAM signals at the site of the subscriber and extracts the VOD content stream. The STB20 then generates an output signal suitable for the subscriber's video equipment (e.g., televisions, recording devices, etc.).
• In operation, the subscriber requests content (e.g., a movie, a nature documentary or a classic sporting event) via the STB20. The STB20 conveys the request to thesession manager14. Thesession manager14 allocates suitable bandwidth resources in theedge QAM16, and instructs theSTB20 to tune to the appropriate frequency spectrum for those resources. Thesession manager14 then directs theVOD server12 to begin streaming the appropriate digital content to theedge QAM16, and theedge QAM16 translates the digital content to the appropriate frequency spectrum.
• One disadvantage of this architecture is that theedge QAM16 is statically mapped to a particular session manager/VOD server combination, and cannot be shared with another session manager. Thesession manager14 inFIG. 1 monitors and controls the resource allocation of theedge QAM16 for VOD content to multiple subscribers. A second session manager/VOD server combination cannot share theedge QAM16 because different session managers cannot communicate to coordinate the edge QAM resources.
• For example, if a cable MSO desires to deploy a second VOD server22 (and associated session manager24) for hosting content different than what is on thefirst VOD server12, thesecond VOD server22 must deliver its content viadifferent edge QAM26 than that used by thefirst VOD server12, as shown inFIG. 2. This arrangement represents a highly inefficient use of network resources.
SUMMARY OF THE INVENTION
• In one aspect, a system for distributing digital content includes two or more digital content sources, each having a separate session manager that is distinct from other session managers associated with other digital content sources. The system further includes at least one set of network resources for receiving digital content from the two or more digital content sources, for modulating the digital content onto a carrier signal suitable for transmission over an access network, and for transmitting the carrier signal over the access network. The system also includes a receiving device for terminating the carrier signal and generating a digital content stream corresponding to the digital content from the two or more digital content sources. The system further includes a policy server for monitoring a utilization state of the network resources, and for allocating a set of bandwidth segments of the at least one set of network resources to the two or more digital content sources.
• The policy server allocates the bandwidth segments according to the utilization state of the at least one set of network resources. Alternatively, the policy server may allocate bandwidth according to a set of policy rules. Policy rules may define resource allocation according to subscriber priority, or they may define resource allocation according to a category of the digital content.
• The receiving device includes a set top box for generating an output signal suitable for one or more subscriber video equipment components, and each of the two or more digital content sources includes a video-on-demand server for providing video content.
• The policy server issues instructions to the session manager associated with a digital content source to send video content to the at least one set of network resources. In one embodiment, the policy server is a video policy server for allocating the set of bandwidth segments of the at least one set of network resources to two or more video content sources.
• The utilization state includes information about how much bandwidth of the at least one set of network resources is allocated and how much bandwidth of the at least one set of network resources is available.
• In another aspect, a method of distributing digital content includes providing digital content from two or more digital content sources, each having a separate session manager that is distinct from other session managers associated with other digital content sources. The method further includes receiving, at one or more sets of network resources, digital content from the two or more digital content sources. The method also includes modulating the digital content onto a carrier signal suitable for transmission over an access network, transmitting the carrier signal over the access network, and terminating the carrier signal and generating a digital content stream corresponding to the digital content from the two or more digital content sources. The method further includes allocating, with a policy server, a set of bandwidth segments of the at least one set of network resources to the two or more digital content sources, and for monitoring a utilization state of the network resources.
• In another aspect, a method of distributing digital content from a content source to a receiving device over a network includes
• • sending an initiating request for digital content, from the receiving device to a session manager associated with the content source;
  • sending a resource request for network resources, from the session manager to a policy server, as a result of the initiating request;
  • evaluating and executing one or more policy rules to determine whether or not the resource request should be granted;
  • sending an instruction from the policy server to the session manager instructing the session manager to send digital content to a specific set of network resources;
  • sending receiving information for receiving the digital content to the receiving device; and,
  • sending digital content from the session manager to the network resources.
• The method further includes sending a notification from the policy server to the network resources notifying the network resources of a transfer of digital content from the session manager to the network resources. The network resources may include edge QAM interfacing devices. The digital content may include video content, and the content source may include one or more video-on-demand servers.
• The method further includes evaluating and executing the one or more policy rules to determine how much bandwidth of the network resources should be allocated to the session manager.
BRIEF DESCRIPTION OF DRAWINGS
• The foregoing and other objects of this invention, the various features thereof, as well as the invention itself, may be more fully understood from the following description, when read together with the accompanying drawings in which:
• FIG. 1 shows a prior art video-on-demand content distribution architecture.
• FIG. 2 shows another view of the distribution architecture inFIG. 1.
• FIG. 3 shows the content distribution architecture of the described embodiment.
• FIG. 4 shows a series of steps for setting up a video session using the architecture inFIG. 3.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
• The described embodiment is a cable network architecture in which a video policy server (VPS) coordinates allocation of network resources among two or more video-on-demand (VOD) servers each coupled to session managers (also referred to herein more generally as video content sources). As used herein, the term “network resources” specifically refer to edge QAM resources, but in general, the network resources may include any network components in the cable network architecture from the data source to the ultimate subscriber destination.
• Although the described embodiment distributes video content across a cable network, the concepts described herein also apply to the distribution of more general digital content, such as video gaming content and other application data from two or more digital content sources. Central to this distribution of digital content is a policy server that allocates network resources to two or more digital content sources based on various considerations such as the utilization state of the network resources and a set of policy rules governing the digital content and the end consumers of the digital content (i.e., the subscribers). This general architecture allows digital content sources to share network resources, where without this architecture, each of those digital content sources would be bound to a single set of network resources.
• In the described embodiment, the VPS takes on the resource allocation functionality that, for prior art architectures, typically resides in the session managers associated with VOD servers. By abstracting the allocation functionality from the session managers and centralizing it in the VPS, the described embodiment allows multiple video data sources to utilize the same set of edge QAM interface devices.
• FIG. 3 shows the described embodiment of a policy-based admission control scheme for use in a cable network architecture. Afirst VOD server102, asecond VOD server104 and athird VOD server106, each accompanied by an associated session manager (108,110 and112, respectively), host digital video content.
• EachVOD server102,104 and106 hosts a large amount of a particular category of video content. For example, thefirst VOD102 server may host full length movie content, thesecond VOD server106 may host classic sports content, and thethird VOD server106 may host nature/wildlife content. Each VOD server merely streams selected video content when instructed by its associated session manager.
• A session manager associated with each VOD server includes all of the functionality necessary for setting up and tearing down a video session. As used herein, a “video session” is transmission of video content from one of the VOD servers, through the cable network, with the video content terminating at the location of the subscriber. The session manager may be integrated into the VOD server, or it may be a separate component either attached to, in close proximity to, or networked with, the VOD server.
• Each VOD server/session manager can provide digital video content to a set of edge QAM interfacing devices114 (referred to herein as “edge QAM”). Theedge QAM114 modulates and up-converts the digital content from the VOD servers, then transmits the resulting QAM signal onto the coaxial infrastructures within anaccess network116.
• Theedge QAM114 is capable of providing a finite amount of throughput bandwidth for the digital content. In the described embodiment, thefirst VOD server102, thesecond VOD server104 and thethird VOD server106 can share the throughput capacity of theedge QAM114, so that each VOD server can utilize one or more bandwidth segments of theoverall edge QAM114 throughput capacity. Each of the bandwidth segments can be any frequency width up to the total bandwidth of theedge QAM114.
• TheSTB120 is a receiving device that terminates the QAM signals at the site of the subscriber and extracts the VOD content stream from the QAM signals. TheSTB120 generates an output signal from the extracted VOD content stream suitable for subscriber video equipment such as televisions, video recorders and the like.
• A video policy server (VPS)118 controls how much throughput bandwidth of theedge QAM114 each VOD/session manager uses. TheVPS118 monitors the utilization state of theedge QAM114, i.e., how much bandwidth of theedge QAM114 is currently being utilized, and how much of theedge QAM114 is available.
• In order for a VOD server/session manager to transmit digital video content through theedge QAM114, the session manager must requestedge QAM114 resources from theVPS118. The session manager specifies a particular amount ofedge QAM114 resources depending upon the nature of the digital video content to be transmitted (e.g., high definition content requires more bandwidth than ordinary video). TheVPS118 evaluates the state of theedge QAM114 to determine if the requested resources are available. If those resources are available, and certain policy criteria are met, theVPS118 admits the VOD server/session manager to the requested edge QAM bandwidth. Once admitted, the VOD server/session manager begins streaming the digital video to theedge QAM114.
• Once theVPS118 allocates edge QAM bandwidth to a VOD server (for example, the first VOD server102), theVPS118 removes that bandwidth from consideration for allocation to other sources. TheVPS118 thus interprets the state of theedge QAM118 as having its availability reduced by the amount of bandwidth allocated to thefirst VOD server102.
• The allocated bandwidth remains unavailable until relinquished by the sourcing VOD server. The allocated bandwidth may be relinquished by, for example, the expiration of a purchase period during which the subscriber can access the video, or a command from the session manager that the video data stream is complete. Once the bandwidth is relinquished, theVPS118 considers that bandwidth available for allocation. As a result, the VPS interprets the state of theedge QAM116 as having its availability increased by the amount of bandwidth relinquished.
• As described above, theVPS118 evaluates certain policy rules in addition to resource availability before allocating resources to a video source. Such policy rules allow for smooth integration of VOD with other data types within the network (e.g., high speed internet access, voice-over-IP, video conferencing, etc.). One type of policy may give priority to certain data types. For example, policy rules may give resource requests from certain data sources preferential treatment by giving them higher priority access to the available resources. Further, policy rules can allow certain high priority data sources to preempt a lower priority data stream that is currently using allocated resources.
• Another type of policy may give priority to particular subscribers, creating a kind of “tier” system. For example, consider a three-tier system where the highest-priority tier is the ‘gold’ tier, the next highest priority tier is the ‘silver’ tier, and the lowest tier is the ‘bronze’ tier. Policy rules involving subscriber tiers give preferential treatment to higher tiers, for which subscribers in those tiers pay a premium price. One exemplary tier-based rule may be:
• • if ((subscriber_tier==bronze)&&(current_network_utilization>80%)) then reject
• With this rule, an allocation request for a bronze-tier subscriber will be rejected if the current resource allocation is greater than80 percent. This and other tier-based policy rules thus function to bias network availability towards the higher paying subscribers.
• FIG. 4 illustrates a series of steps for setting up a video session and the corresponding allocation of resources at theedge QAM116. In this example, a subscriber requests, via the set top box (STB)120, digital video data from thesecond VOD server104 and the associatedsession manager110. Although this example shows the steps for setting up a session from one particular VOD server and session manager, these steps apply for a session with respect to any of the other VOD sources.
• In thefirst step130, theSTB120 requests particular VOD content from thesession manager110 associated with therelevant VOD server104. TheSTB120 determines which of the three is the relevant VOD server and session manager based upon (i) configuration data within theSTB120 and (ii) the nature of the requested VOD content. In this exemplary case, theSTB120 sends the request to thesecond session manager110 because its associatedVOD server104 hosts the particular type of VOD content the subscriber desires (e.g., a recently released movie).
• In thesecond step132, thesession manager110 sends a request to theVPS118 for resource allocation (in this case,edge QAM114 resources). This request includes information such as subscriber ID, subscriber service tier, priority of the content, and streaming characteristics (e.g., constant bit rate/variable bit rate, bandwidth requirements, etc.).
• In thethird step134, theVPS118 evaluates and executes the policy rules defined by the MSO, while considering various factors, in order to decide whether to allocate network resources to thesession manager110. Such factors include the current utilization state of the network resources, the service tier of the requesting subscriber, the nature of the content being requested, among others.
• In thefourth step136, theVPS118 instructs theservice manager110 to send the requested video content to a particular IP address and UDP port. This occurs only if the results of executing the policy rules indicate such instruction is an appropriate action, and if sufficient network resources are available. If the result of executing the policy rules indicate such instruction is an inappropriate action, theVPS118 does not respond to the service manager. Alternatively, theVPS118 may respond to thesession manager110 with a message indicating the request for resource allocation has been denied.
• In some cases, the network resources needed to fulfill the request from the subscriber will not be available, or the policy rules will not allow use of the resources. In these cases theVPS118 will not allocate network resources to thesession manager110. Alternatively, theVPS118 may provide the service manager with alternatives such as using a lower bit-rate stream or sending a request to another VOD server hosting similar content.
• In thefifth step138, theVPS118 notifies therelevant edge QAM114 to expect the video data stream from thesession manager110 and to take any necessary actions. Such actions may include converting the video data to a lower bit rate, changing from constant bit rate to variable bit rate, or other processing actions unique to the incoming VOD content.
• In thesixth step140, thesession manager110 communicates tuning and other information to theSTB120 necessary for receiving the requested VOD content. Such information includes which frequency channel will carry the video content, which MPEG program to monitor for a particular video stream, etc.
• In theseventh step142, thesession manager110 begins to stream the requested VOD content to theedge QAM114, which converts the VOD content stream to the appropriate format for viewing via the STB. TheQAM114 modulates and up-converts the VOD content stream, then transmits the resulting QAM signal onto the coaxial infrastructures within anaccess network116.
• In some cases, the subscriber may choose to “pause” the video session described above once the session is established, and theVPS118 may take different actions as a result depending on policy rules. For example, a subscriber may purchase a time slot (e.g., 24 hours) during which the subscriber can watch the content as many times as he or she desires. During this time slot, the subscriber may stop watching the content before it ends, assuming he or she will return later to watch the remainder of the content. In this case, theservice manager110 informs theVPS118 of the interruption, and theVPS118 may release the reserved resources until the subscriber resumes watching the content. Policy rules may, for example, dictate that those resources will not be released for higher-level subscriber tiers, so that the resources are guaranteed to be available for the entire time slot.
• The above examples do not specify particular communication protocols among the various components. In general, any protocol appropriate for the particular media and content may be used for the communication described above. Specific examples of communication protocols for the above communications are listed below.
• I) Communication Between theSTB120 and the Session Manager110:
• 1. DSMCC—(Digital Storage Media—Command and Control): See ISO/IEC JTC1/SC29/WG11.
• 2. RTSP—(Real Time Streaming Protocol): See RFC-2326 (April 1998).
• II) Communication Between theSession Manager110 and the VPS118:
• 1. RTSP.
• 2. XML (eXtensible Markup Language).
• 3. HTTP (HyperText Transfer Protocol).
• 4. RSVP—(Resource reSerVation Protocol): See RFC-2205 (September 1997).
• III) Communication Between theVPS118 and the Edge QAM116:
• 1. SNMP (Simple Network Management Protocol) See RFCs 1155, 1157, and 1212 for SNMPv1 and RFCs 1441 through 1452 for SNMPv2.
• 2. XML.
• 3. HTTP.
• Other aspects, modifications and embodiments are within the scope of the claims.

Claims (24)

1. A system for distributing digital content, comprising:

two or more digital content sources, each having a separate session manager that is distinct from other session managers associated with other digital content sources;

at least one set of network resources for (i) receiving digital content from the two or more digital content sources, (ii) modulating the digital content onto a carrier signal suitable for transmission over an access network, and (iii) transmitting the carrier signal over the access network;

a receiving device for terminating the carrier signal and generating a digital content stream corresponding to the digital content from the two or more digital content sources;

a policy server for monitoring a utilization state of the network resources, and for allocating a set of bandwidth segments of the at least one set of network resources to the two or more digital content sources.

2. The system ofclaim 1, wherein the policy server allocates the bandwidth segments according to the utilization state of the at least one set of network resources.

3. The system ofclaim 1, wherein the policy server allocates the bandwidth segments according to a set of policy rules.

4. The system ofclaim 3, wherein the policy rules define resource allocation according to subscriber priority.

5. The system ofclaim 3, wherein the policy rules define resource allocation according to a category of the digital content.

6. The system ofclaim 1, wherein each of the two or more digital content sources includes a video-on-demand server for providing video content.

7. The system ofclaim 1, wherein the receiving device includes a set top box for generating an output signal suitable for one or more subscriber video equipment components.

8. The system ofclaim 1, wherein the policy server issues instructions to the session manager associated with a digital content source to send video content to the at least one set of network resources.

9. The system ofclaim 1, wherein the policy server is a video policy server for allocating the set of bandwidth segments of the at least one set of network resources to two or more video content sources.

10. The system ofclaim 1, wherein the utilization state includes information about how much bandwidth of the at least one set of network resources is allocated and how much bandwidth of the at least one set of network resources is available.

11. A method of distributing digital content, comprising:

providing digital content from two or more digital content sources, each having a separate session manager that is distinct from other session managers associated with other digital content sources;

receiving, at one or more sets of network resources, digital content from the two or more digital content sources;

modulating the digital content onto a carrier signal suitable for transmission over an access network;

transmitting the carrier signal over the access network;

terminating the carrier signal and generating a digital content stream corresponding to the digital content from the two or more digital content sources;

allocating, with a policy server, a set of bandwidth segments of the at least one set of network resources to the two or more digital content sources, and for monitoring a utilization state of the network resources.

12. The method ofclaim 11, further including allocating, using policy rules, the bandwidth segments according to the utilization state of the at least one set of network resources.

13. The method ofclaim 11, further including allocating, using policy rules, the bandwidth segments according to a set of policy rules.

14. The method ofclaim 13, further including defining resource allocation according to subscriber priority.

15. The method ofclaim 13, further including defining resource allocation according to a category of the digital content.

16. The method ofclaim 11, further including issuing instructions from the policy server to the session manager associated with a digital content source to send video content to the at least one set of network resources.

17. A method of distributing digital content from a content source to a receiving device over a network, comprising:

sending an initiating request for digital content, from the receiving device to a session manager associated with the content source;

sending a resource request for network resources, from the session manager to a policy server, as a result of the initiating request;

evaluating and executing one or more policy rules to determine whether or not the resource request should be granted;

sending an instruction from the policy server to the session manager instructing the session manager to send digital content to a specific set of network resources;

sending receiving information for receiving the digital content to the receiving device; and,

sending digital content from the session manager to the network resources.

18. The method ofclaim 17, further including sending a notification from the policy server to the network resources notifying the network resources of a transfer of digital content from the session manager to the network resources.

19. The method ofclaim 17, wherein the network resources include edge QAM interfacing devices.

20. The method ofclaim 17, wherein the digital content includes video content, and the content source includes one or more video-on-demand servers.

21. The method ofclaim 17, further including monitoring a utilization state of the network resources.

22. The method ofclaim 17, wherein the policy rules define resource allocation according to subscriber priority.

23. The method ofclaim 17, wherein the policy rules define resource allocation according to a category of the digital content.

24. The method ofclaim 17, furthering including evaluating and executing the one or more policy rules to determine how much bandwidth of the network resources should be allocated to the session manager.

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