Patent Publication Number: US-2009222858-A1

Title: System and Method for Creating Electronic Guides Based on Presence and Group Membership

Description:
TECHNICAL FIELD 
     The present invention relates generally to communication networks, and particularly to communication networks configured to allow members of a group to access and share media files associated with the group members. 
     BACKGROUND 
     Internet Protocol Television (IPTV) is a system that provides digital television service to subscribers. Generally, a subscriber has a device which receives the television signal, and which facilitates user requests to access and receive television content from a variety of different sources. Such a device may comprise, for example, a set-top box (STB) or a television set (TV) configured with the appropriate software. However, rather than delivering the content via traditional broadcast or cable formats, service providers deliver the television content over Internet Protocol (IP) based computer networks. 
     Currently, subscribers to both cable and broadcast television services, as well as those subscribing to similar services delivered over IP networks, can invoke an on-screen menu called an Electronic Program Guide (EPG) to view information about the available IPTV content. Generally, EPGs employ an interactive graphical user interface (GUI) to permit users to view information about current and future programs, navigate to different channels or programs, and select a particular program, for viewing. In suitably equipped systems, such as STBs with the appropriate software and hardware, users may also record selected programs onto a hard disk for later viewing. These types of services may also be available to a user over the network. 
     Conventional IPTV systems provide a generic EPG to identify the television programs that all users have access to. Some, however, also allow individual subscribers to personalize their EPGs according to their preferences. Additionally, other IPTV systems allow groups of people, such as the members of a family, to personalize an EPG according to the common likes and dislikes of all family members. 
     Typically, such family-based EPGs show programs prioritized based on popularity. However, what is popular to one family member is usually not popular with another. Some systems consider individual family member profiles when creating the family EPG, but only to create prioritized lists of programs that the family members have already seen. These systems do not generate prioritized lists of content that individual family members can potentially view. Additionally, conventional systems do not generate EPGs to include the titles of media files from the personal collections of other users. Nor do they consider the viewing preferences of other users, which could affect what a given user might find popular. 
     SUMMARY 
     The present invention provides a method of creating and distributing an electronic guide to users, such as an electronic program guide (EPG) or an electronic service guide (ESG), based on membership in a group and presence information. The electronic guide comprises information that includes, but is not limited to, the titles of media files stored on the users&#39; respective home systems and the locations of those media files. A server generates the electronic guide and, once generated, distributes the electronic guide to the members of the group. As changes occur, the server dynamically generates and distributes an updated electronic guide to the group members. In a preferred embodiment, the server comprises a network server residing in a network, and has a client-server relationship with a variety of different client devices displaying the electronic guide. In another embodiment, however, the server comprises a peer node in a peer-to-peer relationship with other peer nodes displaying the electronic guide. 
     In one embodiment, the users are registered members of an affinity group that inform one another of their presence status using a presence service. Each group member has a media system that is capable of storing and rendering media files, such as audio and video files. The media files may be stored, for example, on a home server in the group members&#39; home systems. The media files may also be stored remotely on a server in a network, and retrieved for rendering on a user&#39;s home system or other rendering device. The network server uses the presence service to subscribe to and receive presence updates from each group member. 
     According to the present invention, the presence updates include information about the shared media files of each of the group members. The information may comprise, for example, the titles of one or more media files stored on a given group member&#39;s home media system that is being shared with the group. The network server generates the electronic guide that includes the information about the shared media files and distributes the electronic guide to the group members. 
     Upon receipt, the group members can display the electronic guide on their home systems to view the media files, and select an available media file from the electronic guide. The selected media file is then delivered from its storage location on the home server or networked storage location of one group member to a rendering device, such as a digital television display, of another group member. This allows group members to share media files and other media assets across a communication network, even though those assets are located in the home system of another group member. Membership in the group serves to authenticate a group member to allow them to access the media files of the other group members. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  illustrates a system suitable for generating Electronic Guides according to one embodiment of the present invention. 
         FIG. 2  illustrates exemplary signaling and data communication paths between some of the entities of  FIG. 1  according to an alternate embodiment of the present invention. 
         FIG. 3  is a flow chart illustrating one embodiment of the present invention. 
         FIG. 4  is a call flow diagram illustrating how a network server creates and disseminates electronic guides to group members based on their group membership and presence according to one embodiment of the present invention. 
         FIG. 5  is a flow chart that illustrates how a group member&#39;s home system uses presence updates to indicate shared media content to a network server. 
         FIG. 6  illustrates exemplary signaling and data communication paths between some of the entities of  FIG. 1  according to an alternate embodiment of the present invention. 
         FIG. 7  is a block diagram illustrating some of the component parts of a network server configured to create and disseminate electronic guides to the members of a group according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     The present invention is a system and method for creating and distributing an interactive on-screen menu for a group of users based on the presence of the group members. In one embodiment, the menu is an Electronic Program Guide (EPG) that lists a variety of personal media assets associated with each of the group members, such as audio and video files that are stored on the respective home servers of the group members. In another embodiment, the menu comprises an Electronic Service Guide (ESG) that identifies a variety of services available from each of the group members. With the present invention, the group members can publish their respective media assets and/or services to the group to share them with the other group members. Additionally, membership in the group may be used to authorize a user&#39;s access to the electronic guide, as well as the media assets and/or services of another group member. 
       FIG. 1  is a block diagram illustrating the architecture of a system suitable for sharing media assets and/or services between the members of a group based on the presence of the group members. System  10  comprises an access network (AN)  12  that communicatively interconnects an end-user media system  20  of one or more group members to a network under the control of the Internet Protocol Multimedia Subsystem (IMS)  70 . In this embodiment, the end-user media system  20  refers collectively to a plurality of individual end-user systems  30 ,  40 ,  50 , and  60 , each of which is associated with a different member of the group. However, two or more of the individual systems  30 ,  40 ,  50 , and  60  may be associated with a single group member. 
     As described below in more detail, a network server in the IMS  70  receives presence updates for the group members. The presence updates include information about each group member&#39;s media assets, such as the titles of the media files stored on each of the end-user systems  20 . Based on this information, the network server generates and publishes an EPG to the group members. The EPG includes a listing of the available media files of each group member. Each group member can view the EPG, and select one or more media files stored on the other systems  30 ,  40 ,  50 ,  60  for rendering on their own system. 
     Access network (AN)  12  provides access to the network controlled by the IMS  70 , and is capable of communicating video and audio data between the subscriber equipment and the network controlled by the IMS  70  using well-known interfaces and signaling protocols. The IMS  70  is not dependent on the technology specific to the AN  12 . Therefore, AN  12  may be any packet-switched network known in the art. Suitable networks may be any fixed or mobile network including, but not limited to, Universal Mobile Telecommunications System (UMTS), cdma2000, General Packet Radio Service (GPRS), Enhanced GPRS (EGPRS) networks, and Asymmetric Digital Subscriber Line (ADSL) networks. 
     Each group member is a member of a group registered with the IMS  70 . In  FIG. 1 , there are four group members—each having their own system  30 ,  40 ,  50 ,  60 , and a variety of equipment to render media files such as audio and/or video files. For example, systems  30  and  40  comprise home theater systems. Each home theater system respectively includes a Digital Media Rendering Device (DMR) such as TV  32 ,  42 , a Home Server (HS)  34 ,  44 , and a Home IMS Gateway (HIGA)  36 ,  46 . While not required for the present invention, the home theater systems  30 ,  40  have similar components and functionality. Therefore, the following description applies to both systems  30 ,  40 , even though only system  30  is specifically mentioned. 
     The DMR may be any device capable of rendering digital video and audio to a user. In one preferred embodiment, the DMR comprises a digital TV  32  that is part of a Digital Living Network Alliance (DLNA) network. A DLNA network allows different electronic devices, such as TV  32 , to interoperate with other electronic devices, such as any computing and mobile communication devices associated with the group member. 
     Generally, the DMR is equipped with software that makes it DLNA compliant. Thus, many different types of devices can be DMRs in the present invention. Suitable examples of suitable DMRs include, but are not limited to, Liquid Crystal Displays (LCDs), Plasma televisions, Personal Computers (PCs), or any other device capable of rendering a television signal. In some embodiments, a set-top box is associated with the TV  32 . The set-top box, which is described in more detail later, could include the software that makes it DLNA compliant. 
     As is known in the art, the group member can store media files locally on the HS  34 . Using the EPG, the group member can select a video, for example, and view the selected video on TV  32 . The group member can also selectively control the video playback using a remote control unit (not shown) as is known in the art. Additionally, audio and/or video files may be delivered to system  30  from a streaming media server, such as an IPTV server, which is associated with the IMS system  70 . In these cases, the media files may be delivered to HS  34  for storage, or to the TV  32  for playback. 
     The HIGA  36  includes a wide array of functionality that bridges the gap between IMS services such as IPTV, and non-IMS enabled devices, such as HS  34 , TV  32 , a home stereo, a personal computer, a media player, and the like. The HIGA  36  may be implemented in a physical box that is separate from the HS  34  and/or TV  32 , or integrated with these devices. In this embodiment, the HIGA  36  comprises a separate device that is configured to interconnect the HS  34  and TV  32  to the IMS  70  via the AN  12 . To facilitate communication, the HIGA  36  includes a device database, containing device addresses and descriptions (as standardized by UPnP) which identifies the addresses of the local home-based non-IMS devices and the network devices that offer the IMS services. The HIGA  36  generates this database as a result of the discovery mechanism which is part of the home networking protocol (UPnP). This is done automatically when a device is connected to the home network. Alternatively if the device is a SIP or IMS device it would perform an explicit register to the HiGA and will thereby be also added to the device DB. The user can then optionally add preferences associated to devices in device DB (e.g. on which one of two discovered TVs to display personalized EGP) 
     As described in more detail later, the HIGA  36  can send presence updates to PS  80  in IMS  70 . These updates can include a list of media files stored on HS  34 , and various interfaces that allow the HIGA  36  to communicate with remote entities using the appropriate protocols. In the present invention, the HIGA  36  periodically receives and stores an EPG generated for the group members from IMS  70 . The EPG includes a listing of the media files stored at each system  30 ,  40 ,  50 ,  60  as well as the addresses of each media file. Using a remote control unit or similar device, the group member can display the group EPG on TV  32  and select a desired media file. The HIGA  36  can then retrieve the selected file from the associated address or location, even if the asset is stored on one of the systems  40 ,  50 ,  60  of another group member, and deliver it to TV  32  for rendering. 
     In addition to home theater systems  30 ,  40 , the present invention may also be used with a personal computing device (PC)  52  associated with another system  50 . PC  52  may comprise a variety of audio and/or video files stored on its hard drive or other associated memory. The group member associated with system  50  may select a media file to render on PC  52 , and share these media files with the other group members for rendering on their respective systems  30 ,  40 ,  60 . The group member may also receive the group EPG detailing the media files and services of the other systems  30 ,  40 ,  60 , and select media files from the EPG for rendering as previously described. 
     As seen in  FIG. 1 , systems  30 ,  40 , and  50  each have an HIGA to facilitate communications with the IMS  70  as previously described. However, those skilled in the art will appreciate that the present invention neither needs nor requires an independent HIGA component. Some or all of these systems  30 ,  40 ,  50  may integrate the HIGA functionality with another component, such as the HS, the set-top box, the TV or the PC. 
     One such system, home system  60 , illustrates this integrated functionality. System  60  includes a wireless communication device  62  capable of communicating voice and/or data with one or more remote parties via AN  12 , and rendering audio and video to its user. Generally, audio and video files are stored in a memory within device  62  and are shared with the other group members as previously described. In this embodiment, device  62  is an IMS client device. Therefore, the functionality provided by the HIGAs of the other systems is included with the device  62  and a separate HIGA is not needed. 
     The IMS  70  provides access independent, IP-based multi-media services to the group members and supports a variety of IP services including voice over IP (VoIP), IPTV, email, web browsing, videoconferencing, instant messaging, presence and other services. Generally, the IMS  70  uses open interfaces and an access independent session control protocol (SCP), such as the Session Initiation Protocol (SIP), to support multi-media applications. Session description protocol (SDP) is used for media negotiation and is described in IETF RFCs 2327 and 3264, both of which are expressly incorporated herein by reference. 
     The IMS  70  includes a variety of servers and databases, some of which are illustrated in  FIG. 1 . As seen in  FIG. 1 , the IMS  70  components comprise a Home Subscriber Server (HSS)  72 , a Call/Session Control Function Server (CSCF)  74 , a Streaming Server (SS)  76 , an XML Document Management Server (XDMS)  78 , a Presence Server (PS)  80 , and an IPTV Acquisition Server (IPTV-AS)  82 . 
     The HSS  72  functions as a central repository for user-related subscription data required to handle multimedia transactions. Such data includes, but is not limited to, location information, security information for both authentication and authorization of group members, user profiles that identify, inter alia, which IMS services a group member subscribes to, and which CSCF  74  serves which group member. IMS  70  may contain multiple HSSs  72 ; however, in such cases, additional components or databases may be used to map group member addresses to their associated HSS  72 . 
     Those skilled in the art will appreciate that the HSS  72  is not the only entity that can store and maintain the user profile information according to the present invention. Rather, any system capable of storing and maintaining user profile information, and which is associated with the user via mediation with the HSS  72 , is suitable for use with the present invention. The XDMS  78 , which is defined by the applicable Open Mobile Alliance (OMA) standards, is one example of an entity suitable for storing and managing the user profile information according to the present invention. 
     The CSCF  74  is a SIP server that communicates with the HSS  72 , the AN  12 , and the IPTV-AS  82 . Generally, the CSCF  74  is configured to process SIP signaling messages in IMS  70  and perform session control functions for the group members. The CSCF  74  comprises software and hardware modules that provide SIP routing services, translation services, and enforce network policies. For example, the CSCF  74  may be configured to allow only authorized group members to perform certain media-related functions, such as establish a media session with IMS  70 . 
     The SS  76  comprises a server that provides synchronous and asynchronous delivery of an audio and/or video stream from IMS  70  to the one or more of the end-user systems  20 . In  FIG. 1 , the SS  76  facilitates “Real-Time” or “On-Demand” type services provided by the IMS  70 , and routes data to the end-user systems  20  that requested the content. However, in some cases, SS  76  may also provide presence status updates to PS  80 , either individually or through the mediation of the IPTV AS  82 . These updates may include information detailing the available media files on the group member&#39;s system. As described in more detail below, this allows the members of a group to share applications and/or media files across the network, as well as receive interactive audio and video streams such as video conferencing. 
     The PS  80  provides presence services to the group members. As is known in the art, a presence service provides information about a group member&#39;s status and location to the other group members. For example, a group member may be available or unavailable to communicate data with another group member. Further, when available, a given group member with a device of limited capabilities may only be able to provide or receive limited types of data. Therefore, the PS  80  may store information defining a given devices&#39; current operational capabilities. 
     The IPTV-AS  82  comprises a control function that generally controls the SS  76  to acquire video and audio content from a variety of sources such as television broadcasting stations and databases of stored audio/video. In the present invention, however, the IPTV-AS  82  also controls the SS  76  to receive audio/video content from a home server  34 ,  44 , PC  52 , or wireless communication device  62  for routing to one or more of the other group members. Typically, the video and audio content arrives at the SS  76  encoded according to any of a variety of known encoding standards. Such standards include, but are not limited to, MPEG-2, and H.264 or VC-1, which are two high-definition video standards designed for television screens. Upon receipt, the IPTV-AS  82  may control the SS  76  to route the content to the CSCF  74  for delivery to the systems  30 ,  40 ,  50 , or to deliver the content to the mobile-based system  60 . In addition, IPTV-AS  82  may include, or interoperate with, one or more functions or systems designed to facilitate or control billing, authentication, and authorization of group members. 
     According to the present invention, the IPTV-AS  82  includes software and hardware configured to request/receive information relating to the media files stored at one or more of the systems  30 ,  40 ,  50 ,  60 . The IPTV-AS  82  receives this information responsive to changes or updates in the presence status of the group members. For example, the IPTV-AS  82  may SUBSCRIBE to receive updated presence information from systems  30 ,  40 ,  50 ,  60 , whenever the presences status of the associated group member changes. The presence information may include, for example, the group member&#39;s presence status. Additionally, however, the presence information may also include attributes or other data that identify the title of a video or audio file, the current location (e.g., a Uniform Resource Identifier (URI) or other identifier) of the audio/video file at the group member&#39;s system, or the audio/video file itself. The IPTV-AS  82  receives this information from the group members, and compiles it to generate a group EPG. The IPTV-AS  82  then outputs at least a part of the group EPG to each group member. Any group member can then view the group EPG and select a video or audio file from this list for rendering, even if the selected file is resident on another group member&#39;s home system  10 . 
       FIG. 2  illustrates some of the components of system  10  in more detail, and some suitable protocols that may be used to facilitate intercommunication according to one embodiment of the present invention. For illustrative purposes only,  FIG. 2  is discussed in the context of the home theater system  30 . However, those skilled in the art should appreciate that the following discussion can apply to any of the systems  30 ,  40 ,  50 , and  60 , of any of group member. 
     As seen in  FIG. 2 , TV  32  includes or is associated with a Hypertext Transfer Protocol (HTTP) client  32   a . The HTTP client  32   a  may, for example, be located in a set-top box or in the TV  32  itself. HS  34  includes a web server application  34   a  and a Content Directory Service (CDS)  34   b . The CDS  34   b  was standardized by the UPnP™ Forum in the “ContentDirectory:1 Service Template Version 1.01” dated Jun. 25, 2002, which is expressly incorporated herein by reference in its entirety. HIGA  36  includes or is associated with an HTTP user-agent  36   a , a presence module  36   b , and a Control Point (CP)  38 . These entities utilize HTTP for signaling and Universal Plug-n-Play (UPnP) to communicate content. Each of these protocols are well-understood in the art, and thus, are not described in detail here. 
     HTTP client  32   a  communicates signaling information with a webserver  34   a  on HS  34  using the well-known HTTP protocol. The signaling messages may be requests for a desired media file stored on HS  34 , or for an EPG from CDS  34   b . The CDS  34   b  is periodically updated from the IPTV-AS  82 , and contains a listing of the audio and/or video files available locally from HS  34 , and/or from one or more of the other group members&#39; systems  40 ,  50 ,  60 . 
     Webserver  34   a , in turn, communicates the signaling messages to/from an HTTP user agent  36   a  on HIGA  36 . The HTTP user agent  36   a  translates the HTTP signaling messages into Session Initiation Protocol (SIP) messages for delivery to the IMS  70 . The HTTP user agent  36   a  also translates SIP signaling messages received from the IMS  70  into HTTP signaling messages for delivery to HS  34 . The CDS  34   b  communicates media content with the CP  38  using the UPnP protocol. 
     The HIGA  36  also includes a presence module  36   b  that communicates the presence status of the group member to the PS  80 . The group member&#39;s presence status may change, for example, whenever the group member powers-on one or more components of system  30 , or adds a media file to, or deletes a media file from, HS  34 . 
     In one embodiment, for example, the CDS  34   b  automatically generates and transmits a signal to the CP  38  upon power up, or when the group member adds/deletes a media file. The signal may comprise information that details the available media files on HS  34 . The information may, for example, specify a title of the media file, the type of content it contains (e.g., audio, video), and a URL or URI address that specifies where on the HS  34  the file is located. Upon receipt, the CP  38  notifies the presence module  36   b . These notifications may include the information received from the CDS  34   b . The presence module  36   b  then generates a SIP UPDATE message to include the information, and transmits the SIP UPDATE message to PS  80 . 
     The IPTV-AS  82  is registered with PS  80  as a “watcher” to the group member. A watcher is a device or software program that registers with the PS  80  to receive presence updates of one or more devices as they occur. Thus, whenever the presence of one of the group members changes, the IPTV-AS  82  is appraised of the change in a presence update message. Typically, presence update messages describe the activity status of a user, such as “IDLE,” or “BUSY,” or “ON-LINE.” In the context of the present invention, however, the update messages may also include the listing of media files and their locations stored on HS  34 . Upon receiving the presence update messages, application module  84  uses the information to generate or modify the group EPG. Once generated, the application module  84  distributes the generated group EPG to each group member. The group members can then display the group EPG and select a desired file from the EPG to render on their respective DMRS, such as TV  32 . 
       FIG. 3  is a flow diagram illustrating an exemplary method  90  for generating and distributing a group EPG based on the presence status of the group members. Using standard procedures and functions, a group is created, and its members register with the IMS  70  (box  92 ). The group members also set up and use their IPTV subscriptions. Next, the group members update their presence status with the PS  80  (box  94 ). With that change or update, information regarding each group member&#39;s media files is sent to the IPTV-AS  82  as previously described. The IPTV-AS  82  uses the information it receives to create the group EPG and distribute the EPG to the group members (box  96 ). Finally, the group member selects a desired media file from the distributed group EPG, which is delivered to the requesting group member via the IMS  70  as previously described for rendering (box  98 ). Thus, with the present invention, the group member can access a media file, even though the requested file may be physically located on a remotely located system, such as a home server in another group member&#39;s system. 
       FIG. 4  is a call flow diagram  100  illustrating an exemplary method for creating group EPGs based on group membership and presence in the context of an IMS network. It is assumed that the individual users have registered in the IMS  70  and have set up their respective IPTV subscriptions with the IPTV-AS  82  (line  102 ). Further, it is assumed that the XDMS  78  has created an affinity group (box  104 ) and that the users have joined the affinity group (line  106 ). The procedures used to register the users, set-up their IPTV subscriptions, and create/update the affinity group are standard and well-known in the art. Therefore, these procedures are not detailed here. 
     After the users have joined the group, the XDMS  78  updates the system  30 ,  40 ,  50 ,  60  of each group member with a user profile (line  108 ). For home systems  30 ,  40 ,  50 , the XMDS  78  may send an update message to the respective HIGAs  36 ,  46 ,  56  for storage in local memory. For mobile-based system  60 , the XMDS  78  may send the user profile to device  62  for storage in local memory. 
     The XMDS  78  may also send a group profile to the IPTV-AS  82  (line  110 ). The group profile may contain information about the members of the group, such as their preferences and device capabilities. For example, some devices, such as wireless communication device  62  may be able to render audio, but not video, to a user. The IPTV-AS  82  can use this information to determine whether a specified type of file can be sent to such a device. Alternatively, the IPTV-AS  82  may use this information to exclude certain media files from an EPG intended for group members having devices not able to render them. Because the profile sent to the IPTV-AS  82  is a group profile, there is no need to send the individual user profiles to the IPTV-AS  82  for storage. 
     Once the group is created and its members registered, the IPTV-AS  82  can subscribe to receive presence updated from each of the group members, which may be sent when the group members update their shared media files. In the exemplary embodiment, the IPTV-AS  82  sends a SIP SUBSCRIBE message to the PS  80  for each group member (line  112 ). This registers the IPTV-AS  82  as a “watcher” for each group member, and thus, allows the IPTV-AS  82  to be kept informed of each group member&#39;s presence status. The PS  80  may send a SIP SUBSCRIBE message to each group member as is known in the art (line  114 ). As described in more detail later, the end-user systems  20  send presence update messages, such as SIP NOTIFY messages, to the PS  80  (line  116 ). These messages may be sent to the PS  80  when the users first join the affinity group, or whenever existing group members add or delete media files from their home systems. As previously described, the presence update messages include the presence status of the group members, as well as the information related to the media files stored at their respective systems  30 ,  40 ,  50 ,  60 . Upon receipt, the PS  80  sends a presence update message to the IPTV-AS  82  (line  118 ). 
     It should be noted here that the devices for some systems, such as communication device  62  of system  60 , may not be capable of storing a large number of media files. As such, at least some media files associated with the user of device  62  may be stored on SS  76 . In these cases, the SS  76  may update the PS  80  with information about these media files (line  120 ) when the user joins the group or changes his media files. The PS  80  would then provide the IPTV-AS  82  with the presence update message as previously described (line  122 ). Once the IPTV-AS  82  receives the presence updates, the IPTV-AS  82  collates the received information with any information content that may already be stored for the other group members to generate the group EPG (box  124 ). 
     Once the IPTV-AS  82  generates the EPG, the IPTV-AS  82  can distribute the EPG to the members of the group. In this embodiment, the IPTV-AS  82  may receive requests from the group members for the EPG (line  126 ). The IPTV-AS  82  then distributes the group EPG to each group member that requests the EPG (line  128 ). The requests may be, for example, explicit requests generated by the group member. Alternatively, the requests for the EPG may be automatically generated and sent without the user&#39;s knowledge. Such implicit requests may occur, for example, whenever a group member powers-up an end-user system that has been configured by the user to perform this function. Alternatively, a given end-user system may request the EPG periodically, or it may automatically be updated whenever the status of another group member changes. In any case, the end-user system may receive all or a portion of the EPG. In some embodiments, the EPG can be pushed to the group members each time the EPG is updated. 
     A group member may then use the group EPG to access a desired media file associated with another member of the group. Particularly, the group member displays the group EPG, and selects a desired media file from the EPG. By way of example, the group member may select a video stored on the HS of another geographically distanced group member system. Responsive to the selection, the HIGA establishes a media session with the HS using known methods. The selected video file is then retrieved from its location on the HS and streamed to the group member that requested the media file. 
       FIG. 5  illustrates an exemplary method  130  of generating and sending presence updates to the PS  80  from the end-user system  20 . As previously stated, the media files associated with each group member are typically stored in the group member&#39;s HS. The end-user systems  20  would be responsible for providing a listing of their shared files when the user joins the group, or when the user changes the media files. 
     By way of example only, the media files of the group member associated with system  30  could be stored on HS  34 . The CDS  34   b  includes a directory listing of those media files. Because the UPnP protocol is used in this embodiment, the CDS  34   b  automatically updates the CP  38  in the HIGA  36  with information related to the media files on HS  34  (box  132 ). The information may include the titles of one or more media files that the group member will share with the other group members, and a location of those media files such as a URL, for example, that defines where a media file is located on HS  34 . In some embodiments, the information may include a copy of the media file content. 
     The CP  38  then collates the information and/or content (box  134 ) and signals the presence module  36   b  (box  136 ). Responsive to the signal, the presence module  36   b  generates the presence update message to include the media information, and sends the presence update to the PS  80  (box  138 ). The PS  80  then forwards the presence update and the information to the IPTV-AS  82  as previously described. 
     Generating the group EPG may increase the processing load of the IPTV-AS  82 . Therefore, the IPTV-AS  82  need not generate the group EPG. In some embodiments, a separate network server connected to the IPTV-AS  82  performs this function. For example, the IPTV-AS  82  could communicate the presence updates to a separate EPG server for EPG generation. Once complete, the EPG server would communicate the updated EPG to the IPTV-AS  82  for dissemination to the end-user systems  20 . Offloading the EPG generation functions to a separate server would allow the IPTV-AS  82  to perform its other conventional functions and minimize any delays that the extra processing might incur. 
     Distributing the group EPG to the group members&#39; respective systems  30 ,  40 ,  50 ,  60  may be performed using any method known in the art. By way of example, the IPTV-AS  82  may push the group EPG to each group member using SIP or HTTP. Alternatively, the IPTV-AS  82  may send a SIP message to each system  30 ,  40 ,  50 ,  60  to notify each system that an updated group EPG is available. Responsive to this trigger, the HIGAs, for example, could request and receive the updated group EPG using one or more messages formatted according to a protocol such as SIP, HTTP, SMS, or the like. 
     Each of the group members can determine when and how they receive the group EPG based on their presence. For example, a group member&#39;s presence may be updated whenever the member watches TV. In such cases, the IPTV-AS  82  may not send updated EPGs to that group member while that group member is watching TV. Additionally, the EPGs can indicate to the other members that the group member is watching TV, and in some embodiments, which TV program the group member is watching. 
     Further, where media files are shared between group members, the group membership is used as the authorization. Thus, the HIGA, for example, can access the group membership list responsive to receiving a request for a particular file. If the requesting party is a member of the group, that user is authenticated and authorized to receive the requested file. Otherwise, that user request is denied. This negates the need for a system to individually query a requesting user for authentication. 
     Additional security is also possible, however. For example, one embodiment requires that each group have one or more uniquely assigned broadcast channels. Information regarding these assignments may be transmitted to the group members as part of the group EPG. Thereafter, any request for a media file that is received over one of the identified broadcast channels is considered authenticated. 
     In other embodiments, the distributed EPG may carry signed URLs associated with the media files. Whenever a user requests a media file, the HIGA sends the signed URL to establish the media channel. Because the URL is signed, the HIGA/HS retrieving the media file can authenticate the user. Other methods, such as the use of individual or group-level passwords, are also suitable. 
     The present invention also facilitates digital rights management and billing functions. For example, charging group members for the media files may be applied at a group level or to individual group members using the profiles stored at the XDMS  78 . Charges may be based on a URL associated with a selected file and billed in any manner known in the art. 
       FIG. 6  illustrates another embodiment in which HS  34  includes a content management tool  34   c . With this software module, the group member associated with system  30  can control access to media files stored on HS  34  by specifying which of the other group members can or cannot access a given media file. Additionally, the group member could use the content management tool  34   c  to specify whether a given media file should be marked for home-use only, and thus, not published to the other group members. Such control may be provisioned when the group member adds the media file to the home server, for example, or when the group member desires to alter the access rights to one or more media files. 
       FIG. 7  is a block diagram illustrating some of the component parts of the IPTV-AS  82 . As seen in  FIG. 7 , the IPTV-AS  82  comprises a controller  86 , a memory  88 , and a communication interface  89 . The controller may, for example, be any of a variety of programmable microprocessors that control the operation of IPTV-AS  82  according to instructions and data stored in memory  88 . Such program instructions include, for example, the application module  84  that generates and distributes the group EPG from the received presence updates. The communication interface  89  includes interfaces that permit the IPTV-AS  82  to communicate with one or more network entities using an appropriate protocol. Interface  89   a , for example, communicatively connects the IPTV-AS  82  to the PS  80 . Presence notifications are sent and received over this interface. Interface  89   b  allows the communication of user and group profiles with the XDMS  78 . Interface  89   c , which may comprise an IP. multimedia service control (ISC) interface, facilitates communications with the CSCF  84 , and interface  89   d  permits communications with SS  76 . 
     As previously stated, the IPTV-AS  82  receives presence updates and composes a group-specific EPG based on those presence updates. These functions may occur periodically at predetermined time intervals, whenever the presence of one or more group members changes, whenever a group member requests the group EPG, or responsive to some combination thereof. 
     Further, generating the EPG may be based on information included in some or all of the individual group member profiles, or in the conglomerate group member profile. The IPTV-AS  82 , for example, may process this information to determine user preferences and capabilities, and to determine the content of the group EPGs or individual EPGs distributed to the group members. 
     The present invention may, of course, be carried out in other ways than those specifically set forth herein without departing from essential characteristics of the invention. The present embodiments are to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.