Patent Publication Number: US-9847844-B2

Title: Technique for usage forecasting in a switched digital video system

Description:
FIELD OF THE INVENTION 
     The present invention relates generally to the electrical, electronic, and computer arts, and more particularly relates to video content networks. 
     BACKGROUND OF THE INVENTION 
     With the advent of digital communications technology, many TV program streams are transmitted in digital formats. For example, Digital Satellite System (DSS), Digital Broadcast Services (DBS), and Advanced Television Standards Committee (ATSC) program streams are digitally formatted pursuant to the well-known Moving Pictures Experts Group 2 (MPEG-2) standard. The MPEG-2 standard specifies, among other things, the methodologies for video and audio data compression allowing for multiple programs, with different video and audio feeds, to be multiplexed in a transport stream traversing a single transmission channel. A digital TV receiver may be used to decode an MPEG-2 encoded transport stream, and extract the desired program therefrom. 
     The compressed video and audio data are typically carried by continuous elementary streams, respectively, which are broken into access units or packets, resulting in packetized elementary streams (PESs). These packets are identified by headers that contain time stamps for synchronizing, and are used to form MPEG-2 transport streams. For digital broadcasting, multiple programs and their associated PESs are multiplexed into a single transport stream. A transport stream has PES packets further subdivided into short fixed-size data packets, in which multiple programs encoded with different clocks can be carried. A transport stream not only includes a multiplex of audio and video PESs, but also other data such as MPEG-2 program specific information (sometimes referred to as metadata) describing the transport stream. The MPEG-2 metadata may include a program associated table (PAT) that lists every program in the transport stream. Each entry in the PAT points to an individual program map table (PMT) that lists the elementary streams making up each program. Some programs are open, but some programs may be subject to conditional access (encryption), and this information (i.e., whether open or subject to conditional access) is also carried in the MPEG-2 transport stream, typically as metadata. 
     The aforementioned fixed-size data packets in a transport stream each carry a packet identifier (PID) code. Packets in the same elementary streams all have the same PID, so that a decoder can select the elementary stream(s) it needs and reject the remainder. Packet-continuity counters may be implemented to ensure that every packet that is needed to decode a stream is received. 
     A video content network, such as a cable television network, may provide many different services; for example, free on demand, movies on demand, subscription video on demand, switched digital video, and the like. In at least some instances, a user begins watching program material by requesting establishment of a session, such as a switched digital video session. In at least some cases, there may be inadequate bandwidth to establish the requested new session and also maintain all existing sessions. Thus, network bandwidth allocation is of interest in many cases. 
     A digital video recorder (DVR) is a consumer electronics device or application software that records video in a digital format to a disk drive or other memory. 
     SUMMARY OF THE INVENTION 
     Techniques are disclosed for usage forecasting in a switched digital video system. 
     In one aspect, an exemplary method includes the step of polling a plurality of digital video recorders to extract data indicative of recordings scheduled thereon, the polling being carried out over a video content network by a component at a node in the video content network that is remote from the plurality of digital video recorders; using at least a portion of the data to obtain a prediction of future switched digital video channel usage for the video content network; and carrying out at least one network management activity on the video content network in response to the prediction of future switched digital video channel usage for the video content network. 
     In another aspect, an apparatus is provided for use in a video content network having a plurality of digital video recorders coupled thereto. The apparatus includes at least one memory and at least one processor, which is coupled to the at least one memory, and operative to carry out or otherwise facilitate performance of one or more method steps. 
     As used herein, “facilitating” an action includes performing the action, making the action easier, helping to carry the action out, or causing the action to be performed. Thus, by way of example and not limitation, instructions executing on one processor might facilitate an action carried out by instructions executing on a remote processor, by sending appropriate data or commands to cause or aid the action to be performed. 
     One or more embodiments of the invention or elements thereof can be implemented in the form of an article of manufacture including a machine readable medium that contains one or more programs which when executed implement such step(s); that is to say, a computer program product including a tangible computer readable recordable storage medium (or multiple such media) with computer usable program code for performing the method steps indicated. Furthermore, one or more embodiments of the invention or elements thereof can be implemented in the form of an apparatus including a memory and at least one processor that is coupled to the memory and operative to perform, or facilitate performance of, exemplary method steps. Yet further, in another aspect, one or more embodiments of the invention or elements thereof can be implemented in the form of means for carrying out one or more of the method steps described herein; the means can include (i) hardware module(s), (ii) software module(s), or (iii) a combination of hardware and software modules; any of (i)-(iii) implement the specific techniques set forth herein, and the software modules are stored in a tangible computer-readable recordable storage medium (or multiple such media). 
     These and other features and advantages of the invention will become apparent from the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a functional block diagram illustrating an exemplary hybrid fiber-coaxial (HFC) network configuration; 
         FIG. 1A  is a functional block diagram illustrating one exemplary HFC cable network head-end configuration; 
         FIG. 1B  is a functional block diagram illustrating one exemplary local service node configuration; 
         FIG. 2  is a block diagram of a “switched” hybrid fiber coax cable CATV system useful with one or more embodiments of the present invention; 
         FIG. 3  illustrates selected carriers for transmitting program materials and control messages in a forward passband of the system of  FIG. 2 ; 
         FIG. 4  is a block diagram of a controller used in the system of  FIG. 2 ; 
         FIG. 5  is a table used by the controller for dynamically assigning the carriers for transmission of program materials; 
         FIG. 6  illustrates a data format of a request processed by the controller; 
         FIG. 7  is a flow chart illustrating a process for processing the request; 
         FIG. 8  is a flow chart illustrating a process for retiring an unused carrier; 
         FIG. 9  is a functional block diagram illustrating one exemplary broadcast switched architecture (BSA) network useful with one or more embodiments of the present invention; 
         FIG. 10  is a block diagram of a set-top terminal; 
         FIG. 11  is a functional block diagram of a video content network with a session resource manager; 
         FIG. 12  shows exemplary components of a session resource manager; 
         FIG. 13  shows additional details of an exemplary session resource manager in its environment; 
         FIG. 14  shows a session manager to session gateway component; 
         FIG. 15  shows a session manager to service gateway component; 
         FIG. 16  shows a first exemplary session allocation; 
         FIG. 17  shows a second exemplary session allocation; 
         FIG. 18  is a flow chart of exemplary method steps, according to an aspect of the invention; 
         FIG. 19  is a block diagram of an exemplary computer system useful in implementing at least a portion of one or more embodiments of the invention; and 
         FIG. 20  presents an example of predicted usage, according to an aspect of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       FIG. 1  illustrates a typical content-based network configuration  100 . Note that one or more embodiments are particularly pertinent for switched digital networks as discussed below. The various components of the network  100  include (i) one or more data and application origination points  102 ; (ii) one or more content sources  103 , (iii) one or more application distribution servers  104 ; (iv) one or more video-on-demand (VOD) servers  105 , and (v) consumer (or customer) premises equipment (CPE)  106 . Also included is a dynamic bandwidth allocation device (DBWAD)  1001  such as a global session resource manager, which is itself a non-limiting example of a session resource manager, as discussed elsewhere herein. The distribution server(s)  104 , VOD servers  105 , DBWAD  1001 , and CPE(s)  106  are connected via a bearer (e.g., hybrid fiber cable (HFC)) network  101 . A simple architecture is shown in  FIG. 1  for illustrative brevity, although it will be recognized that comparable architectures with multiple origination points, distribution servers, VOD servers, and/or CPE devices (as well as different network topologies) may be utilized consistent with the invention. For example, the head-end architecture of  FIG. 1A  (described in greater detail below) may be used. 
     It should be noted at this point that in addition to a conventional HFC network or a switched digital network to be discussed below, other kinds of video content networks can be employed for network  101  (e.g., fiber-to-the-home (FTTH) or fiber-to-the-curb (FTTC)). 
     The data/application origination point  102  comprises any medium that allows data and/or applications (such as a VOD-based or “Watch TV” application) to be transferred to a distribution server  104  (for example, over a suitable network, not separately numbered). This can include for example a third party data source, application vendor website, compact disk read-only memory (CD-ROM), external network interface, mass storage device (e.g., Redundant Arrays of Inexpensive Disks (RAID) system), etc. Such transference may be automatic, initiated upon the occurrence of one or more specified events (such as the receipt of a request packet or acknowledgement (ACK)), performed manually, or accomplished in any number of other modes readily recognized by those of ordinary skill. 
     The application distribution server  104  comprises a computer system where such applications can enter the network system. Distribution servers per se are well known in the networking arts. 
     The VOD server  105  comprises a computer system where on-demand content can be received from one or more of the aforementioned data sources  102  and enter the network system. These servers may generate the content locally, or alternatively act as a gateway or intermediary from a distant source. 
     The CPE  106  includes any equipment in the customers&#39; premises (or other appropriate locations) that can be accessed by a distribution server  104 ; for example, set-top terminal (STT), digital set-top box (DSTB), set-top box (STB), or simply “box,” and the like. 
     Referring now to  FIG. 1A , one exemplary embodiment of a head-end architecture is described. As shown in  FIG. 1A , the head-end architecture  150  comprises typical head-end components and services including billing module  152 , subscriber management system (SMS) and CPE configuration management module  308 , cable-modem termination system (CMTS) and out-of-band (OOB) system  156 , as well as LAN(s)  158 ,  160  placing the various components in data communication with one another. It will be appreciated that while a bar or bus LAN topology is illustrated, any number of other arrangements (e.g., ring, star, etc.) may be used consistent with the invention. It will also be appreciated that the head-end configuration depicted in  FIG. 1A  is high-level, conceptual architecture and that each multi-service operator or multiple system operator (MSO) may have multiple head-ends deployed using custom architectures. 
     The architecture  150  of  FIG. 1A  further includes a multiplexer/encrypter/modulator (MEM)  162  coupled to the HFC network  101  adapted to “condition” content for transmission over the network. The distribution servers  104  are coupled to the LAN  160 , which provides access to the MEM  162  and network  101  via one or more file servers  170 . The VOD servers  105  are coupled to the LAN  158 , although other architectures may be employed (such as for example where the VOD servers are associated with a core switching device such as an 802.3z Gigabit Ethernet device; or the VOD servers could be coupled to LAN  160 ). Since information is typically carried across multiple channels, the head-end should be adapted to acquire the information for the carried channels from various sources. Typically, the channels being delivered from the head-end  150  to the CPE  106  (“downstream”) are multiplexed together in the head-end and sent to neighborhood hubs (see  FIG. 1B ) via a variety of interposed network components. 
     Content (e.g., audio, video, etc.) is provided in each downstream (in-band) channel associated with the relevant service group. To communicate with the head-end or intermediary node (e.g., hub server), the CPE  106  may use the out-of-band (OOB) or DOCSIS® (Data Over Cable Service Interface Specification) channels (registered mark of Cable Television Laboratories, Inc., 400 Centennial Parkway Louisville Colo. 80027, USA) and associated protocols. The OpenCable™ Application Platform (OCAP) 1.0, 2.0, 3.0 (and subsequent) specification (Cable Television laboratories Inc.) provides for exemplary networking protocols both downstream and upstream, although the invention is in no way limited to these approaches. All versions of the DOCSIS and OCAP specifications are expressly incorporated herein by reference in their entireties for all purposes. 
     It will also be recognized that multiple servers (broadcast, VOD, or otherwise) can be used, and disposed at two or more different locations if desired, such as being part of different server “farms”. These multiple servers can be used to feed one service group, or alternatively different service groups. In a simple architecture, a single server is used to feed one or more service groups. In another variant, multiple servers located at the same location are used to feed one or more service groups. In yet another variant, multiple servers disposed at different location are used to feed one or more service groups. 
     In some instances, material may also be obtained from a satellite feed  1108 ; such material is demodulated and decrypted in block  1106  and fed to block  162 . Conditional access system  157  may be provided for access control purposes. Network management system  1110  may provide appropriate management functions. Note also that signals from MEM  162  and upstream signals from network  101  that have been demodulated and split in block  1112  are fed to CMTS and OOB system  156 . 
     Also included in  FIG. 1A  are a global session resource manager (GSRM)  302 , a Mystro Application Server  104 A, and a business management system  154 , all of which are coupled to LAN  158 , and discussed further below. GSRM  302  is one specific form of a DBWAD  1001  and is a non-limiting example of a session resource manager. 
     As shown in  FIG. 1B , the network  101  of  FIGS. 1 and 1A  comprises a fiber/coax arrangement wherein the output of the MEM  162  of  FIG. 1A  is transferred to the optical domain (such as via an optical transceiver  177  at the head-end  150  or further downstream). The optical domain signals are then distributed to a fiber node  178 , which further distributes the signals over a distribution network  180  to a plurality of local servicing nodes  182 . This provides an effective 1:N expansion of the network at the local service end. 
     US Patent Publication 2003-0056217 of Paul D. Brooks, entitled “Technique for Effectively Providing Program Material in a Cable Television System,” the complete disclosure of which is expressly incorporated herein by reference for all purposes, describes one exemplary broadcast switched digital architecture useful with one or more embodiments of the present invention, although it will be recognized by those of ordinary skill that other approaches and architectures may be substituted. In a cable television system in accordance with the Brooks invention, program materials are made available to subscribers in a neighborhood on an as needed basis. Specifically, when a subscriber at a set-top terminal selects a program channel to watch, the selection request is transmitted to a head end of the system. In response to such a request, a controller in the head end determines whether the material of the selected program channel has been made available to the neighborhood. If it has been made available, the controller identifies to the set-top terminal the carrier which is carrying the requested program material, and to which the set-top terminal tunes to obtain the requested program material. Otherwise, the controller assigns an unused carrier to carry the requested program material, and informs the set-top terminal of the identity of the newly assigned carrier. The controller also retires those carriers assigned for the program channels which are no longer watched by the subscribers in the neighborhood. 
     Note that reference is made herein, for brevity, to features of the “Brooks invention”—it should be understood that no inference should be drawn that such features are necessarily present in all claimed embodiments of Brooks. 
     The Brooks invention is directed to a technique for utilizing limited network bandwidth to distribute program materials to subscribers in a community access television (CATV) system. In accordance with the Brooks invention, the CATV system makes available to subscribers selected program channels, as opposed to all of the program channels furnished by the system as in prior art. In the Brooks CATV system, the program channels are provided on an as needed basis, and are selected to serve the subscribers in the same neighborhood requesting those channels. 
       FIG. 2  illustrates hybrid fiber coax (HFC) cable CATV system embodying the principles of the Brooks invention for providing program materials to set-top terminals on the subscriber premises. As shown in  FIG. 2 , the system includes head end  150 , fiber node  178 , cable distribution network  180 , and service area node  182  which is connected to set-top terminals  106 - 1  through  106 - n  in a neighborhood, where n is a predetermined number. 
     In head end  150 , program material processing unit  202  receives program materials from various sources via satellites, terrestrial microwave transmissions, cable, etc. The program materials are processed by unit  202  to form K individual program data streams in a digital format, where K is an integer. Each program data stream contains program material, which requires a transmission channel having a specified frequency band for its distribution. In order to fully appreciate the Brooks invention, the term “transmission channel” used here should not be confused with a “program channel.” A “transmission channel” signifies a designated frequency band through which a program data stream containing program material is transmitted. On the other hand, a “program channel” signifies the source of the program material selected by a subscriber to view. For example, a subscriber may select program channel 2 to view program material provided by CBS, program channel 14 to view program material provided by ESPN; program channel 32 to view program material provided by MTV, etc. In this instance, there are K program channels corresponding to the K program data streams. 
     In accordance with the Brooks invention, under control of controller  212 , switching unit  204  selects and switches a subset of the K program data streams, say, p program data streams, to modulator bank  206 , where p≦K. The program data streams in the subset are selected in a manner described below. Each selected program data stream is transmitted through a different transmission channel after it modulates a carrier associated with the transmission channel in a designated forward passband. As is well known, in the United States the designated forward passband for cable TV ranges from 50 MHz to 550 MHz. 
       FIG. 3  illustrates M carriers, C 1  through C M , associated with M transmission channels in the forward passband, respectively, which are pre-selected for use in this instance. Since the forward passband is limited in bandwidth, M in this instance represents the maximum number of carriers or transmission channels that the forward passband can accommodate. As shown in  FIG. 3 , the carrier frequency of C 1  is denoted CF 1 ; the carrier frequency of C 2  is denoted CF 2 ; . . . ; and the carrier frequency of C M  is denoted CF M . In addition, in accordance with the invention, a control carrier CC having a carrier frequency CCF is assigned to carry control messages by controller  212  to the set-top terminals through a control channel in the forward passband. 
     In prior art, each program channel is fixedly assigned to one of the M carriers for transmission of its program material. In addition, all of the program channels are simultaneously made available to each set-top terminal in a neighborhood. As a result, the number of program channels that a prior art CATV system can provide cannot exceed M. However, the Brooks invention overcomes the prior art limitations by dynamically assigning carriers to carry program materials of only those program channels selected by the set-top terminals (or subscribers) in a neighborhood. Advantageously, the number of program channels that the inventive CATV system can provide, although not simultaneously, can exceed M. That is, K can be greater than M in this instance. 
     Thus, in accordance with the Brooks invention, controller  212  communicates to switching unit  204  through link  216 , causing unit  204  to switch, to modulator bank  206 , the selected p program data streams which contain the program channel materials selected aggregately by the subscribers in the neighborhood. As long as p≦M, which is very likely stemming from the fact that the majority at a given time watch only a few particular favorite program channels, controller  212  manages to assign p carriers to carry the respective data streams. To that end, controller  212  also specifies to unit  204  the selected inputs of modulator bank  206  to which the p data streams are switched. 
     In this instance, modulator bank  206  includes conventional modulators. Each input to modulator bank  206  is fed to a different modulator for modulating the input onto one of the M carriers. The p data streams are switched by unit  204  to the appropriate inputs of modulator bank  206  to be modulated onto the p assigned carriers, resulting in p data signals representing the modulated carriers, respectively. In addition, controller  212  transmits control messages described below, through link  214 , to modulator bank  206  where a modulator modulates the control messages onto the aforementioned control carrier, resulting in a control signal representing the modulated control carrier. 
     Combiner  208  combines the p data signals and control signal to form a combined signal, which is fed to optical transceiver  210 . The latter generates an optical signal representing the combined signal. The optical signal traverses optical fiber  213  to fiber node  178 . A transceiver (not shown) in fiber node  178  which performs the inverse function to transceiver  210  converts the optical signal back to the combined signal in electrical form. The combined signal traverses cable distribution network  180  to service area node  182 , where the combined signal is multicast to set-top terminals  106 - 1  through  106 - n . A set-top terminal may tune to the control carrier frequency CCF and extract the control signal from the received combined signal. The control signal may contain information identifying the carrier which is assigned to carry the program channel material selected by the set-top terminal. Based on any such information, the set-top terminal tunes to the frequency of the identified carrier and extracts the corresponding data signal from the received combined signal. The selected program channel material is then derived in a well-known manner from the extracted data signal for viewing. 
     Referring to  FIG. 4 , controller  212  includes processor  4004  of conventional design, which is connected to memory  4006  and interface  4002 . In accordance with the Brooks invention, processor  4004  receives, from one or more of set-top terminals  106 - 1  through  106 - n , requests for materials of program channels selected thereby. Such requests are processed by processor  4004  in accordance with routines stored in memory  4006  which are described below. It suffices to know for now that in response to one such request, processor  4004  causes switching unit  204  to switch the program data stream corresponding to the requested program channel to a selected input of modulator bank  206  and assigns an unused carrier for transmitting the data stream if processor  4004  has not done so. In addition, processor  4004  transmits a control message receivable by the requesting set-top terminal, which includes the information identifying the carrier assigned by processor  4004  to carry the requested program channel material. As mentioned before, based on such information, the requesting set-top terminal tunes to the frequency of the identified carrier to obtain the selected program channel material. 
     To manage the dynamic assignment of carriers for transmitting requested program channel materials to each neighborhood, an assignment table is used in this instance which is stored in memory  4006 .  FIG. 5  illustrates such an assignment table (denoted  5000 ), which includes columns  5004 ,  5006  and  5008 . Column  5004  enumerates each program channel X selectable by a subscriber through a set-top terminal, which ranges from 1 to K in this instance. Column  5006  tracks, for each program channel X, the number of subscribers in the neighborhood who have selected that program channel to watch (N PCHX ). Column  5008  includes entries identifying the carriers assigned by processor  5004  to carry the respective materials of program channels X. Thus, with assignment table  5000 , processor  4004  has knowledge that, for example, referring to row  5011 , carrier C 3  (one of the carriers C 1  through C M ) is assigned for program channel 2 (X=2) which 12 subscribers (N PCHX =12) have selected to watch. In addition, as indicated in row  5013 , no subscriber (N PCHX =0) has selected to watch program channel 1 (X=1). Thus, in accordance with the Brooks invention, no carrier (Null) is assigned for program channel 1. That is, program channel 1 material is currently not transmitted to service area node  182  and thus not currently made available in the neighborhood. 
     When a subscriber at a set-top terminal selects a different program channel to watch, a request for material of the newly-selected program channel is sent from the set-top terminal to controller  212 , as shown at  218 . It should be noted at this point that each of set-top terminals  106 - 1  through  106 - n  is pre-assigned with an identifier for identifying the set-top terminal.  FIG. 6  illustrates the request which includes, inter alia, STID field  6002  containing an identifier identifying the requesting set-top terminal, PCH NEW  field  6004  containing the newly-selected program channel number, and PCH OLD  field  6006  containing the previously-selected program channel number. Thus, for example, if the subscriber changes the program channel selection from channel 8 to channel 2 (or in other words “deselects” channel 8 in favor of channel 2), the value of PCH NEW  field  6004  would be set to “8” and that of PCH OLD  field  6006  would be set to “2.” If the subscriber has just turned on the cable TV to watch program channel 9, the value of PCH NEW  field  6004  in that instance would be set to “9” and that of PCH OLD  field  6006  would be set to “0,” indicating an off state. Conversely, if the subscriber who has been watching program channel 9 chooses to turn off the cable TV, the value of PCH NEW  field  6004  would be set to “0” and that of PCH OLD  field  6006  would be set to “9.” 
     Referring back to  FIG. 2 , the above-described request is generated by the requesting set-top terminal, say, terminal  106 - 1 , which incorporates a cable modem for modulating a specified carrier in a reverse passband with the request data. As is well known, in the United States the reverse passband, which ranges from 5 MHz to 42 MHz, is allocated for transmission of signals from set-top terminals to a head end to realize interactive services, e.g., the inventive cable TV service of Brooks. The modulated signal from terminal  106 - 1  representing the request data is fed to service area node  182 , from where it is forwarded to fiber node  178  through cable distribution network  180 . In fiber node  178 , the aforementioned optical transceiver (not shown) generates an optical signal representing the modulated signal. The optical signal traverses optical fiber  215  to optical transceiver  210  in head end  150 . Optical transceiver  210  converts the optical signal back to the modulated signal in electrical form. The modulated signal is then demodulated by demodulator  230  to recover the original request, which is fed to controller  212  through link  218 . In response to the received request, controller  212  invokes a first routine stored in memory  4006 . 
     Instructed by the first routine, processor  4004  reads the received request, as indicated at step  7002  in  FIG. 7 . At step  7004 , processor  4004  determines whether PCH NEW  field  6004  in the request has a nonzero value f, 1≦f≦K. If not, i.e., the PCH NEW  field value is equal to “0” indicating that the subscriber&#39;s cable TV has been turned off, the routine comes to an end. Otherwise, processor  4004  at step  7006  looks up, in assignment table  5000 , the value of N PCHX  with X=f in this case. At step  7008 , processor  4004  determines whether the N PCHX  value just looked up equals 0. If N PCHX =0, analogous to the previously described situation with respect to row  5013  of table  5000 , no carrier has been assigned to carry the requested program channel material to service area node  182 . That is, the requested program material is currently not made available to the neighborhood. In that case, processor  4004  at step  7010  assigns an unused carrier to carry the requested material of program channel X=f. The new carrier may be selected to avoid as much as possible noise and interference with other carriers being used to optimize the cable TV quality. At step  7012 , processor  4004  updates assignment table  5000  to include the identity of the carrier assigned for program channel X=f. Processor  4004  at step  7016  communicates to switching unit  204 , directing it to switch the program data stream associated with program channel X=f to the proper input of modulator bank  206  such that the program channel material is modulated onto the newly-assigned carrier. At step  7018 , processor  4004  generates a control message responsive to the received request, which is to be read by the requesting set-top terminal, terminal  106 - 1  in this instance. The control message includes, among other information, the STID from the request identifying terminal  106 - 1  which is the intended recipient of the message, and the identity of the assigned carrier carrying the requested program channel material. The control message is transmitted through the control channel in a manner described before and multicast from service area node  182  to the set-top terminals in the neighborhood. In particular, terminal  106 - 1  is tuned to the control channel and reads the STID information in the control message, which identifies terminal  106 - 1  in this instance. Recognizing that it is the intended recipient of the message, terminal  106 - 1  goes on to read other information in the message including the identity of the assigned carrier carrying its selected program channel material. With the knowledge of the assigned carrier&#39;s identity, terminal  106 - 1  tunes to the frequency of the assigned carrier to receive the selected program channel material. 
     In any event, the routine proceeds from step  7018  to step  7020  where processor  4004  increments the value of N PCHX  with X=f in assignment table  5000  by one, reflecting the fact that an additional subscriber (or set-top terminal) in the neighborhood has selected program channel X=f to view. Referring back to step  7008 , if processor  4004  determines that the value of N PCHX  with X=f does not equal 0, i.e., at least one set top terminal currently receiving program channel X material carried by a previously assigned carrier, the routine proceeds to step  7014 . Processor  4004  at step  7014  looks up, in assignment table  5000 , the identity of the carrier previously assigned for program channel X=f. The routine then proceeds to step  7018  described before. 
     Reference should now be had to  FIG. 8 . After the first routine is completed, a second routine is preferably invoked to perform a garbage collection function for retiring any carrier carrying program material which is no longer selected by any set-top terminal in the neighborhood. Instructed by this second routine, processor  4004  at step  8004  determines whether PCH OLD  field  6006  in the received request has a nonzero value g, 1≦g≦K. If not, i.e., the PCH OLD  field value equal to “0” indicating that the subscriber&#39;s cable TV has just been turned on, the second routine comes to an end. Otherwise, processor  4004  at step  8006  looks up, in assignment table  5000 , the value of N PCHX  with X=g in this case. At step  8008 , processor  4004  decrements the N PCHX  value just looked up by one, reflecting the fact that one fewer subscriber (or set-top terminal) in the neighborhood selected program channel X=g to view. Processor  4004  at step  8010  determines whether the resulting N PCHX  value equals 0. If not, the second routine comes to an end. Otherwise, if N PCHX =0, i.e., program channel X=g no longer selected by any subscriber (or set-top terminal) in the neighborhood, the second routine proceeds to step  8012 . Processor  4004  at step  8012  searches assignment table  5000  for the identity of the carrier assigned for program channel X=g. Processor  4004  at step  8014  communicates to switching unit  204 , causing unit  204  to stop switching the program data stream corresponding to program channel X=g to modulator bank  206 , thereby terminating the transmission of the program data stream otherwise carried by the identified carrier. Processor  4004  at step  8016  places the identified carrier in reserve by substituting the carrier identity entry with “Null” in assignment table  5000 . 
     In some instances, the system in  FIG. 2  may be used to serve multiple neighborhoods. Furthermore, in some cases, the system of  FIG. 2  can readily accommodate what is known in the art as a picture-in-picture (PIP) feature providing simultaneous viewing of multiple program channels. In that case, a set-top terminal supporting the PIP feature requests materials of multiple program channels and simultaneously tunes to the assigned carriers carrying the requested program materials. 
     In the event that the carriers in the CATV system of  FIG. 2  are oversubscribed, i.e., no available carrier can be assigned by controller  212  to carry new program material requested by a set-top terminal in the neighborhood, “blocking” may be implemented such that the requesting set-top terminal is temporarily denied access to the new program material. However, the requesting set-top terminal may be instructed by controller  212  to tune in the meantime to a pre-set channel reserved for the blocking purposes. For example, this pre-set channel may carry commercials, infomercials, coming movie attractions, etc., in addition to a stand-by notice informing the subscriber of the unavailability of the requested program material. Alternatively, controller  212  may transmit a text message including the stand-by notice to the requesting set-top terminal to be shown to the subscriber. In either event, as soon as a carrier becomes available, controller  212  transmits another notice to the requesting set-top terminal to inform the subscriber of the availability of the requested program material, followed by a control message identifying the carrier newly assigned to carry such material. In response to this control message, the set-top terminal tunes to the frequency of the identified carrier to obtain the requested program material. 
     Moreover, the request of  FIG. 6  may automatically be generated by a set-top terminal to deselect a program channel as soon as an event on the program channel such as a movie is over. For example, by setting a time-out clock in the head end or set top terminal to track the play time of the event, the request, with PCH NEW =0, is transmitted as soon as the time-out period corresponding to the length of the event or a fixed time expires. If no other set-top terminals in the same neighborhood tune to the frequency of the carrier assigned for the program channel, the assigned carrier will be retired in accordance with the Brooks invention. Thus, at an event boundary, a program channel may be deselected based on a fixed or variable time-out period. 
     In some cases, if a request cannot be granted to a requesting set top terminal, due to inadequate bandwidth, a search can be carried out for one or more sessions that can be shut down to free up bandwidth; in at least some instances, based on a suitable time-out period (e.g., four hours). 
     The request for deselecting a program channel may also be automatically generated by a set-top terminal in response to a lack of an audience. For example, the set-top terminal may incorporate detection technologies such as motion detectors, acoustic sensors and/or infrared sensors, which are used to detect presence of any viewers in front of the set-top terminal by their movement, voice and/or body heat. If it is determined that no viewer is present, the request for deselecting the program channel is automatically generated by the set-top terminal. 
       FIG. 9  illustrates another exemplary “switched” network architecture also useful with one or more embodiments of the present invention. A so-called “broadcast switched architecture” or BSA network is illustrated in this exemplary embodiment. 
     Switching architectures allow improved efficiency of bandwidth use for ordinary digital broadcast programs. Ideally, the subscriber will be unaware of any difference between programs delivered using a switched network and ordinary streaming broadcast delivery. 
       FIG. 9  shows the implementation details of one exemplary embodiment of this broadcast switched network architecture. Specifically, the head-end  150  contains switched broadcast control and media path functions  190 ,  192  (the latter including staging processor  195 ); these elements cooperate to control and feed, respectively, downstream or edge switching devices  194  at the hub site which are used to selectively switch broadcast streams to various service groups. A BSA server  196  is also disposed at the hub site, and implements functions related to switching and bandwidth conservation (in conjunction with a management entity  198  disposed at the head-end). An optical transport ring  197  is utilized to distribute the dense wave-division multiplexed (DWDM) optical signals to each hub in an efficient fashion. 
     With respect to  FIG. 9 , note that in some current head ends (e.g., those using technology from Motorola, Inc., Schaumburg, Ill., USA) there is no explicit GSRM or digital network control system (DNCS); rather, VOD vendors implement required functionality in their own proprietary way. In other head end configurations, such as in those implemented by Time Warner Cable, Inc., New York, N.Y., USA, GSRM functionality, as described herein, can be employed. Accordingly, it should be understood that the embodiments herein are exemplary and non-limiting, and one or more embodiments of the invention can be implemented with a variety of different devices that are used to carry out appropriate functionality. For example, a session resource manager apparatus could be implemented in many different ways, and is not limited to the specific GSRM/SRM examples shown in the figures. 
     In addition to “broadcast” content (e.g., video programming), the systems of  FIGS. 1-9  may also deliver Internet data services using the Internet protocol (IP), although other protocols and transport mechanisms of the type well known in the digital communication art may be substituted. One exemplary delivery paradigm comprises delivering MPEG-based video content, with the video transported to user personal computers (PCs) (or IP-based set-top boxes (STBs)) over DOCSIS channels comprising MPEG (or other video codec such as H.264 or AVC) over IP over MPEG. That is, the higher layer MPEG or other encoded content is encapsulated using an IP protocol, which then utilizes an MPEG packetization of the type well known in the art for delivery over the RF channels. In this fashion, a parallel delivery mode to the normal broadcast delivery exists; i.e., delivery of video content both over traditional downstream quadrature amplitude modulation (QAM) channels (QAMs) to the tuner of the user&#39;s STB or other receiver device for viewing on the television, and also as packetized IP data over the DOCSIS QAMs to the user&#39;s PC or other IP-enabled device via the user&#39;s cable modem. 
     Referring again to  FIG. 9 , the IP packets associated with Internet services are received by edge switch  194 , and forwarded to the cable modem termination system (CMTS)  199 . The CMTS examines the packets, and forwards packets intended for the local network to the edge switch  194 . Other packets are discarded or routed to another component. Note also that edge switch  194  in block  150  in  FIG. 9  can, in the most general case, be the same or different as that shown in the hub site of  FIG. 9 . Also, in other embodiments, CMTS  199  could be located in a place other than the hub site. 
     The edge switch  194  forwards the packets received from the CMTS  199  to the QAM modulator  189 , which transmits the packets on one or more physical (QAM-modulated RF) channels to the CPEs  106 . The IP packets are typically transmitted on RF channels that are different that the RF channels used for the broadcast video and audio programming, although this is not a requirement. The CPE  106  are each configured to monitor the particular assigned RF channel (such as via a port or socket ID/address, or other such mechanism) for IP packets intended for the subscriber premises/address that they serve. 
     It will be appreciated that while some descriptions presented herein are described in the context of Internet services that include multicast and unicast data, there is potential applicability to other types of services that include multicast transmission of data delivered over a network having multiple physical channels or even virtual or logical channels. For example, switching between various physical channels that comprise a virtual channel, can itself be conducted according to the “switched” approach. As a simple illustration, if a first virtual channel is comprised of physical channels (e.g., QAMs) A, B and D, and a second virtual channel is comprised of QAMs C, E and F, a cable modem (CM) or other CPE can be configured to switch between the A/B/D and C/E/F virtual channels as if they were a single QAM. 
     The configurations shown in  FIGS. 1-9  are exemplary in nature and different approaches may be used in other embodiments; such other approaches may have more or less functionality (for example, high speed Internet data services might be omitted in some cases). 
       FIG. 10  shows an example of a set-top terminal  900 , which is one form of CPE  106 . A conventional “Watch TV” application (denoted  903  in  FIG. 10 ) is installed in the set-top terminal (denoted  900 ) to service those program channels (or programs) afforded the traditional broadcast service. Watch TV application  903 , residing in memory  910 , provides such well known functions as channel navigation control, channel selection in response to a channel change event, etc. A channel change event occurs when a user at set-top terminal  900  issues a command to change from one program channel to another. Such a command may be issued, say, using a remote control (not shown), which signal is receptive by set-top terminal  900 . Memory  910  in this instance comprises one or more caches, disks, hard drives, non-volatile random access memories (NVRAMs), dynamic random access memories (DRAMs), read-only memories (ROMs), and/or Flash ROMs. 
     For example, in memory  910 , NVRAM may be used for storage of a user&#39;s settings and set-top terminal configuration settings, such as parental control codes, favorite channel lineups, set-top terminal setups, channel maps, authorization tables, and FDC address assignments. DRAM may be used for most application and operating system storage requirements, such as stacks, heaps, graphics, interactive program guide data, marketing data and usage data, and functions such as MPEG-2 video decompression, DOLBY DIGITAL® (registered mark of Dolby Laboratories Licensing Corporation, San Francisco, Calif.) Adaptive Transfer Coding 3 (AC-3) audio decoding, and video manipulation. ROM may be used for storage of the operating system. Flash ROM may be used for storage of resident application software, as well as patches of the operating system and application software, which software and/or patches are downloaded to set-top terminal  900  from head-end  150  after set-top terminal  900  has been deployed at the user&#39;s premises. 
     Processing unit  905  orchestrates the operations of set-top terminal  900 . It executes instructions stored in memory  910  under the control of the operating system. Service application manager (SAM)  907  forms part of such an operating system of terminal  900 . SAM  907  is responsible for, among other things, monitoring channel change events; administering channel, service and other tables in terminal  900 ; and maintaining a registry of applications in terminal  900 . One such application is the aforementioned Watch TV application  903  which is invoked to service a traditional broadcast channel (or program). Another potential application is a so-called “NPVR TV” application  912  which is invoked to service NPVR (network personal video recorder) enabled channels (or programs), and which may be downloaded from head-end  150  to memory  910 . Application  912 , among other things, emulates the functionality of a personal video recorder by responding to rewind, pause and fast-forward commands initiated by a user, and communicating such commands to head-end  150  through interface  921  to perform the trick mode (i.e., rewind, pause and fast-forward) functions on programs. In addition, for example, application  912  not only allows a user to reserve future broadcast programs for review, but also reserve, play or restart programming content that has broadcast. Interface  921  allows receipt of in-band and out-of-band material from head end  150 , as well as sending communications to the head end via a reverse data channel (for example, of the kind(s) discussed above). 
     In some instances, terminal  900  provides digital video recorder (DVR) functionality. For example, memory  910  may include a hard disk  981  for storing digital programs to be recorded. Some portions of memory  910  (e.g., ROM and some RAM) may be located on processing unit  905 . While terminal  900  may provides DVR functionality, in other instances, separate set-top terminals are associated with separate DVRs. 
     In some instances of memory  910 , NVRAM may be used for storage of a user&#39;s settings and set-top terminal configuration settings, such as parental control codes, favorite channel lineups, set-top terminal setups, channel maps, authorization tables, and forward data channel (FDC) address assignments. DRAM may be used for most application and operating system storage requirements, such as stacks, heaps, graphics, interactive program guide data, marketing data and usage data, and functions such as MPEG-2 or MPEG-4 video decompression, DOLBY DIGITAL® (registered mark of Dolby Laboratories Licensing Corporation, San Francisco, Calif.) Adaptive Transfer Coding 3 (AC-3) audio decoding, and video manipulation. ROM may be used for storage of the operating system  982 . Flash ROM may be used for storage of resident application software, as well as patches of the operating system and application software, which software and/or patches are downloaded to set-top terminal  900  from head-end  150  after set-top terminal  900  has been deployed at the user&#39;s premises. 
     Communication with head end  150  or other intermediate nodes (e.g., for polling and the like) may be through interface  921 . Instructions for what programs are to be recorded may be stored in a location  984 , and polled via interface  921 . Interface  921  may include an RF front end (including demodulator and decryption unit) for interface with the network, as well as a plurality of different types of interfaces (e.g., video/audio interfaces, IEEE-1394 “Firewire”, USB, serial/parallel ports, etc.) for interface with other end-user apparatus such as televisions, personal electronics, computers, WiFi/PAN or other network hubs/routers, etc. Other components which may be utilized within the terminal  900  include RF tuner stages, buffer memory (which may be implemented in RAM or otherwise), various processing layers (e.g., DOCSIS MAC or DAVIC OOB channel, MPEG, etc.) as well as media processors and other specialized system-on-chip (SoC) or application-specific integrated circuit (ASIC) devices. These additional components and functionality are, in and of themselves, well known to those of ordinary skill in the cable and embedded system fields, and accordingly are not described further herein. 
     The terminal  900  may also be provided with an OCAP-compliant monitor application and Java-based middleware which, inter alfa, manages the operation of the terminal and applications running thereon. It will be recognized by those of ordinary skill that myriad different device and software architectures may be used consistent with the invention. 
     Memory  910  can include a number of applications, and an operating system (kernel)  982 . A resource manager  983  may also be provided. 
     One or more embodiments employ session resource management (SRM) functionality to manage video-on-demand and/or switched digital sessions. Preferably, the SRM provides an element that is compatible across a number of head end platforms, such as Motorola, OpenCable, Overlay (SA/Moto) and Scientific-Atlanta (SA). One exemplary embodiment of an SRM is a global session resource manager (GSRM).  FIG. 11  shows an exemplary GSRM environment  300 , which encompasses an interface to an external policy manager, switched digital video support, and third party entitlement control message generator (ECMG) interfaces. An additional goal is to maintain and reuse currently available interfaces and protocols. Interfaces into an external policy manager may be implemented, for example, via a static XML interface or a dynamic SOAP/XML interface. 
     GSRM  302  interfaces with conditional access controller  157 , which in turn interfaces with digital network control system  308  and TED (transactional encryption device)  310  as well as digital access control system  312  and KLS (key list server)  314 . Such interface may employ, for example, open conditional access interface (OCAI) such as SOAP/RPC (remote procedure call). GSRM  302  may also interface with an external policy manager  304 , using, for example, extensible markup language (XML(SOAP)) as described in greater detail below. The skilled artisan will appreciate that “SOAP” stands for Simple Object Access Protocol. Also, DNCS  308  may carry out management and CPE configuration analogous to block  308  in  FIG. 1A . 
     Note that a TED is typically present in a system from Cisco Systems, Inc., San Jose, Calif., USA, or a system from Scientific Atlanta (now also part of Cisco Systems, Inc.), and manages the cryptographic keys while the KLS performs analogous functions in systems from Motorola, Inc. of Schaumburg, Ill., USA. These are non-limiting examples of general functionality for managing cryptographic keys. Thus, elements  308 ,  310  are generally representative of systems from Scientific Atlanta while elements  312 ,  314  are generally representative of Motorola systems. 
     Furthermore, the GSRM may interface (for example, using session setup protocol, SSP) with a business management system, such as the Time Warner Cable MYSTRO business management system (BMS)  154 . BMS  154  is in turn coupled to billing block  152 . The business management system may in turn interface with an application server  104 A, such as a Time Warner Cable MYSTRO application server, using, for example, interactive services architecture (ISA). The BMS  154  may also interface with a suitable VOD server  105 , such as an ISA VOD system, again, using, for example, ISA. 
     Yet further, GSRM  302  may interface with a suitable media flow block  322 , which may include a video staging system  195 , a transcoder and/or transrater  316 , a network encryptor  324 , and a number of QAMs  318 . Communication with block  316  may be, for example, via a suitable transcoder control interface, providing an interface from the GSRM to a transcoder or trans-rater to carry out MPEG manipulation, re-encoding, and the like; communication with block  162  may be, for example, via remote procedure call (RPC) or a suitable network encrypter control interface from GSRM to network encrypter  324 ; and communication with the QAMs may be, for example, via RPC or edge QAM-C (EQUAM-C). Note that in  FIG. 1A , encryption  324  and modulation  318  are combined in block  162 . Element  320  is a router. 
     MAS  104 A may be coupled to DNCS  308  or digital access control system  312  as the case may be. 
     The skilled artisan will appreciate that a messaging interface from the GSRM to a transcoder or trans-rater device, or to a network encrypter, can be implemented, for example, using RPC (remote procedure call) or RTSP (real time streaming protocol) messaging to outline the characteristics of the desired code, rate, or encryption parameters. A transcoder might, for example, convert from MPEG-2 to MPEG-4, in the case where an end client supports MPEG-4. In the case of a trans-rater or statistical multiplexer type of device, the goal is to fit more video programs into a QAM, so the programs are statistically multiplexed together “on-the-fly.” 
     A suitable switched digital video server  306  may also be provided, including SDV RM (switched digital video resource manager to manage resources assigned to the SDV system) and SDV PM (switched digital video policy manager) functionality (not separately numbered). Communication between GSRM  302  and server  306  may be implemented, for example, using session setup protocol server initiated session (SSP-SIS). Server  306  may communicate with QAMs  318  via RPC or EQAM-C. A set top terminal or box (STB)  106  may communicate with VOD server  105  via, for example, lightweight stream control protocol (LSCP); with SDV server  306  via, for example, channel change protocol (CCP); and with GSRM  302  via, for example, session setup protocol (SSP). 
     As shown in  FIG. 12 , the SRM  302  encompasses three major functions, namely, element and network manager  402 , session manager  404 , and policy manager  490 . In the first function, the element manager  402  provides provisioning and configuration information for the edge devices (e.g., edge QAMS  318 ) and network encrypter  324 . The second function  404  handles the assignment of network and RF resources for devices generating session requests. Additionally, the SRM  302  needs access, via a secure interface, to the conditional access (CA) system  157  to provide for content security. The third function, policy manager  490 , provides the ability to allocate these resources based on pre-determined and real time policies as related to the type of asset and/or program requesting bandwidth from the network, in addition to predetermined techniques that can be used when such policies do not apply. The internal policy manager  490  receives rule-sets via an XML file and/or supports a SOAP/XML interface for real time policy decisions. 
     In some instances, the SRM functionality resides physically on the VOD server  105 , while in other cases it is split between two entities, the VOD server  105  and a session resource manager of the DNCS  308 . 
     The Element and Network Manager component  402  is responsible for a number of functions. Listed below is an overview of the primary components:
         A provisioning system for edge devices, video servers, switched digital video servers, network encrypter, network elements, switches, and the like.   Monitoring of various network components to provide SRM engine ability to make session decisions based on available resources.   Managing entitlement messages and conditional access keys, when applicable.   Ability to provide a graphical representation of network components and related interconnects, including setting under/over-provisioning of interconnects.   Ability to provide a graphical interface  408  for designing and managing the network topology and interfaces.       

     The network manager preferably constantly monitors network usage and reports congestion, failures, downed links, and the like. A significant aspect of the network manager is to provide high (for example, 99.99%) uptime of the network for the delivery of video services. In addition, the network manager is preferably able to proactively provide alternate links (when available) to traffic to minimize service interruptions and stream/session failures. 
     In a preferred embodiment, to provide the operator with suitable monitoring capabilities, the network manager provides the ability to show the current network utilization of any device and interconnect links. The information is preferably provided in a graphical manner to the operator and highlights any troublesome or failed devices or connections (for example, using the graphical user interface (GUI)  408 . A layer representing the various communications protocols is shown at  410 . 
     As shown in  FIG. 13 , resource manager  406  of  FIG. 12  preferably includes network resource manager (NRM)  502 , core resource manager (CRM)  504 , and edge resource manager (ERM)  506 . The NRM  502  is responsible for receiving resource requests from the session managers (VOD  520 , SDV  522 , Shell  524 , and so on). After the NRM receives the request, it will then look at what is needed to service the request (encryption, bandwidth, and the like) and then make the requests from the core and edge resource managers  504 ,  506 . The NRM  502  needs to be aware of all of the network (core and edge) resources and their state, so it can make session resource decisions. For instance, if an edge device does not support encryption and the session needs to be encrypted, then the NRM must use the appropriate core encryption device to encrypt the session. Functionally, the NRM, CRM and ERM may be bundled as one process and/or component, or as separate processes and/or components. Note that RTSP stands for real-time streaming protocol. The network monitoring functionality is shown at  526 . 
     With regard to policy manager  490 , in one or more embodiments, with business rules manager enabled, session allocation and most network resources can be assigned based on a pre-defined set of business rules. For example, a high-definition (HD) VOD session may be given preference over a free on-demand session. While this is one example, the system is preferably modular, extensible and configurable to allow operators to set the parameters of the business rules engine. 
     It is also preferred that an operator can determine rules and parameters for the loading of network elements and connections. Instead of purely looking at business rules, new techniques and static configurations may be used for allocating resources on a per-stream and/or per-session or product basis. Some versions of the policy manager (PM)  490  inside the GSRM may allow for XML import of static policy rule sets. Preferably, the GSRM provides a GUI  408  for setting the policies and modifying them. The PM  490  may also support a dynamic policy interface via SOAP/XML to an external policy manager system  304 . 
     A significant function of the session manager (SM)  404  is to provide the mechanism for session requests to receive the proper conduit for the delivery of video. The primary responsibility of the SM is for handling DSM-CC session requests from a VOD client residing on a client device (e.g. STB, and the like). Each time a session is created, the SM must communicate with policy manager  490  and resource manager  406  to determine the best route for the session to be streamed and also determine if, where, and how the session will be set up based on the system policies. Additionally, the GSRM will provide the application server  104  with the appropriate information to determine the type of stream to be created (e.g. MPEG-4 Advanced Video Codec (AVC)) and conditional access method. Non-limiting examples of conditional access methods include the Cisco PowerKEY® conditional access system (registered mark of Cisco Systems, Inc., San Jose, Calif., USA) for a set-top box or the Motorola MediaCipher™ system (mark of Motorola, Inc. of Schaumburg, Ill., USA). 
     The session manager also works in a split model with SDV manager  522  to receive session requests (pre-provisioned/shell or exclusive/provision) for allocating network resources for this request. It is the responsibility of the GSRM to provide a shell session manager to track and manage shell session requests from an external session manager. The shell session manager should maintain a list of granted shell sessions, even through a reboot, power outage, etc. Additionally, the shell session manager should provide reconciliation tools for the external session manager (e.g. SDV server  306 ) and query tools for status checking with QAMs. 
     As seen in  FIG. 14 , in some instances, a session gateway process  1602  resides on the BMS  154  and serves as the entry point for session messaging from DSM-CC to ISA. The GSRM  302  forwards all VOD session communication along to the session gateway and the BMS in turn forwards it to the service gateway  1604 .  FIG. 14  outlines an exemplary interface structure of the session gateway process residing in the BMS. 
     Reference should now be had to  FIG. 15 . In some instances, the GSRM and ISA VOD infrastructure may gain certain efficiencies in session setup speed and reliability by moving the session gateway process  1602  onto the GSRM, as shown at  1702  in  FIG. 15 . The GSRM would then communicate directly to the service gateway  1604  on the ISA bus. Inasmuch as part of the client session request is a descriptor for the service gateway, the GSRM would use this descriptor to pass the appropriate session request information to the referenced service gateway. 
     The ISA bus is primarily directed towards using Common Object Request Broker Architecture (CORBA) for messaging the ISA interfaces. Direct communication of the GSRM to the service gateway would require the GSRM to implement the appropriate ISA and CORBA interfaces. Other alternatives to the CORBA interface include SOAP/XML. 
     It is preferred that a variety of different interfaces be supported by GSRM and the related components and processes, so as to permit interface with hardware and software from many manufacturers, such as Motorola, Scientific-Atlanta and Overlay (Moto/SA) systems. The aforementioned SSP reflects an implementation of the ISO/IEC 13818 MPEG-2 DSMCC specification, incorporated herein by reference in its entirety for all purposes. 
     The SRM  302  manages a pool of HFC and network resources across many edge devices (e.g., edge QAMS  318 ) and reaching multiple service groups. Note that core devices may include, for example, network encrypters, transcoders, statistical multiplexers, and the like. For the setup of a particular session, the SRM allocates resources from the aforementioned pool. The qualified resources are determined by the service group specified by the STB  106 . A mechanism that indicates that an edge device has been removed from service, and thereby its resources must be removed from the allocation pool, is provided in one or more embodiments. The element manager  402  configures the edge device with static configuration information such as modulation mode, transport ID (frequency), as well as provisioning the MPEG-2 multi-program transport stream. This information must be communicated to the SRM so that is can be transmitted to the STB along with session specific information during session set-up. 
     Service applications and clients communicate to the SRM using the session setup protocol, an implementation of DSM-CC. Certain parameters such as retransmission rate for the messages are not defined within the specification. These must be defined or left as configurable parameters for the SRM. In some instances, these messages are actually passed through the session gateway to provide a distributed object interface for the sessions. 
     In SSP, the client  106  sends a client session request to the GSRM  302  to begin the session establishment. This request contains information for identifying the service group as well as information pertinent to the server application. The GSRM verifies the message integrity and passes it along to the server with which the session is desired (e.g., VOD server  105 , BMS  152 ,  154 , application server  104 , SDV server  306 ). The server makes a server add resource request to the SRM, including the amount of downstream bandwidth, MPEG Program and server conditional access. Also included is the Ethernet descriptor if the application desires to indicate a preference. In another aspect, the “server add resource” request may include only a source parameter, allowing the GSRM  302  to respond with the appropriate resources. 
     The SM will determine resource availability after consulting with the resource manager  406  and policy manager  490 . If the resources are available, the GSRM  302  will allocate the appropriate resources and signal an indication of success back to the server. If the system requires encryption, the GSRM  404  will send a suitable request for same to the DNCS CA Manager (CAM)  157 . If the requested resources are available, the CAM will reply with a confirmation. The GSRM  302  then will send the appropriate CA credentials to the client and encryption device. 
     At this point, the server provides a response in which the IP address of the service entry point is specified. In case of failure, the GSRM adds the resources back to the pool. The GSRM uses the HFC resources allocated from the pool to construct a confirmation including modulation mode, transport ID, bandwidth, client conditional access and service entry IP address. The SRM handles a client release request message to allow the client to abort in progress session setups. Once the session has been created, the application server  104 , SDV server  306 , and/or VOD System  105  will create the appropriate stream for the client. 
     The GSRM&#39;s role as the “global” resource manager places it in the position to manage, monitor and control the network (incl. HFC) resources for sessions. To provide a robust QAM sharing ability, the GSRM should be the central arbiter between VOD and SDV sessions. SDV Server  306  will reside external to the GSRM server and will utilize the SSP-SIS extensions to request session bandwidth. The SDV server may request this bandwidth using one of a few methods:
         Shell session (pre-provision)   Exclusive session (shell or RM provisioned)   Combination of shell and exclusive       

     The GSRM is preferably agile enough to handle all these modes simultaneously from an external SDV system  306 . 
     Since Network Resources become more valuable and scarce with each session request from clients and servers, the GSRM preferably provides a method for arbitrating these requests. The GSRM sets session thresholds based on product type for VOD (e.g., free on demand (FOD), movies on demand (MOD), subscription video on demand (SVOD), etc.) and switched digital video (SDV). The MSO can define the name of the product and amount of allowable sessions per service group. In addition, the system provides a way to proactively request session resources back from a client and/or SDV manager. A ceiling can be prescribed by product and/or service and when the ceiling is exceeded requests and/or teardowns could be done on the least preferable sessions (for instance, FOD). The described functionality provides a level of policy control on the sessions being allocated by the GSRM. The GSRM preferably provides the ability to easily support an external policy manager  304  via a SOAP/XML interface that provides extended capabilities. 
     The Session Resource Manager functionality may reside on a single component such as a VOD server or may be spread across multiple components. In one or more embodiments, the Session Resource Manager (SRM) is the central mechanism for aligning head end resources to establish a peer-to-peer connection between the video server and the end user&#39;s set-top box (STB). A sub-component of the SRM is the actual bandwidth allocation technique. With the addition of High Definition Video-On-Demand to the current offering of Standard Definition Video-On-Demand, appropriate techniques should be employed to support the commingling of High Definition Video-On-Demand (HDVOD) and Standard Definition Video-On-Demand (SDVOD) content and the establishment of Quality of Service (QoS) guarantees between the two different services. 
     The narrowcast bandwidth of the VOD service group is arguably the most expensive bandwidth within the cable system. Video server streams, transport, switching fabric, QAMs, RF-combining and distribution all contribute to this cost, which is distributed over a relatively small subset of subscribers. Additionally, this narrowcast bandwidth is re-created over and over again to provide service to all subscribers. Regardless of the infrastructure or of the protocol or which component is actually performing the allocation (Business Management System (BMS)  154 ; Digital Network Control System (DNCS)  308  or VOD Server  105 ) it is preferred, for operational predictability, that any or all of the components optimize and allocate the bandwidth in the same manner. 
     When performing traffic model analysis, significant variables that contribute to the performance of the system are the probability of the arrival of the session setup request and the probability of the session hold-time. These variables contribute to the loading factor with respect to a blocking factor, which ultimately determines the number of resources required to serve a given population of users. 
     Historically, when working with a single encode rate the system-blocking factor was based on the VOD Service Group. With the commingling of different encode rates, a new blocking factor is introduced into the system. This is the QAM blocking factor, and it is based on the probability of having enough bandwidth to support an HD session within a given QAM. While there may be enough bandwidth within the VOD Service Group to support an HD session, if it is not all available on a single QAM channel, the HD session is blocked and the bandwidth is considered “stranded” with regard to its ability to support an HD session. This occurs when the bandwidth consumption on a given QAM exceeds the max rate of the QAM minus the HD rate or, for example, 37.5 Mbps-15 Mbps equaling 22.5 Mbps. 
     Additionally, the probability of whether the next session request to arrive is either a SD or HD session factors into the allocation technique. This probability is based on multiple factors including HD STB penetration rates, buy rates, demographics and content availability. The hold-time of a session will also be impacted based on the length of HD content offered. 
     The allocation models presented herein represent a view of the allocation of sessions by ignoring the hold-time of sessions. Presenting this material without representing the departure of session does not invalidate the allocation technique as session hold-time, and thus session departure, has been factored into the allocation models. The reason that it does not invalidate the allocation technique is that each allocation decision is made at the time of session setup with the most current snapshot of bandwidth allocations across all QAMs within the service group. 
     While the examples are centered around SD content encoded at 3.75 Mbps and HD content at 15 Mbps the allocation technique can easily support multiple SD and multiple HD encode rates by tuning the various parameters. Additionally, service groups with greater than four RF channels are easily supported without any changes. 
     Non-limiting assumptions for the examples include:
         1. Each VOD Service Group includes four 6 MHz RF channels running QAM256.   2. The Standard Definition (SD) rate is 3.75 Mbps. The High Definition (HD) rate is 15 Mbps or four times the SD rate. Thus, the bandwidth requirement for HD is four times that of SD.   3. Every QAM256 channel has the capacity or payload to transport 37.5 Mbps of MPEG-2 video out of a total capacity of 38.8 Mbps. The additional QAM bandwidth is reserved for overhead for encryption, sessions, etc.   4. Although the specification uses sessions as a simplified unit of measure for bandwidth, all decisions are really based on bandwidth and not the number of sessions of a particular rate (of course, other approaches can be used in other instances)   5. The bandwidth utilization and allocation within a QAM does not experience fragmentation as occurs within RAM memory stacks. Thus, there is not the problem of seeking a “largest free block” as all the remainder bandwidth is available for allocation.       

     Several new variables are introduced in order to provide control of how bandwidth is allocated per service group. They are the VType(2)_Session_Limit and the VType(1)_Session_Limit. Control and flexibility can be attained when these two variables are used in conjunction with an optimized allocation technique. 
     Configuring the system with hard limits and not over-subscribing the system will reserve bandwidth and guarantee service for each individual service. Configuring the system in an oversubscription model (defining the sum of both variables to a value greater than the total capacity) allows for a floating pool of resources that will be allocated as requests arrive. Oversubscription has the advantage that the bandwidth is not stranded through the reservation process, if there are no requests for that service, while at the same time providing QoS guarantees. The following examples illustrate this. 
     Example 1: VType(2)_Session_Limit=32 and VType(1)_Session_Limit=2: The hard limits reserve the bandwidth and guarantee service for both SDVOD and HDVOD—in this case 32 SD sessions and 2 HD sessions. Even if there are no HD sessions and the 33rd SD session request arrives, it will be denied. 
     Example 2: VType(2)_Session_Limit=40 and VType(1)_Session_Limit=8: In this totally over-subscribed example setting the variables to their theoretical maximum values allows the system to operate freely without any controls, first come first served. 
     Example 3: VType(2)_Session_Limit=40 and VType(1)_Session_Limit=2: This example allows the possibility of no more than two HD sessions, but does not guarantee them while allowing up to 40 SD sessions. 
     Example 4: VType(2)_Session_Limit=32 and VType(1)_Session_Limit=8: This example allows the possibility of 32 SD sessions and reserves bandwidth for two HD sessions while supporting the possibility of eight HD sessions. 
     The allocation technique is preferably optimized to:
         Support configurability for a “Least Loaded” and a “Most Loaded” session allocation model   Compromise between load balancing across QAMs and HD session support   Enable lowest impact on active session in the event of failures   Increase the probability of having capacity for an HD session   Establish a mechanism to manage a QoS of SD and HD sessions within a VOD Service Group   Implement business rules guaranteeing service levels for both SD and HD sessions   Support multiple SD and multiple HD encode rates   Support varying number of channels per service group   Allow dynamic tuning of network utilization       

     To maintain parity among implementations of the technique, the following variables types are employed.
         VType(n)_Threshold: The variable represents the upper bandwidth threshold to switch between the least loaded model to the most loaded model.   VType(n)_Session_Limit: The variable represents the maximum number of simultaneous VType sessions within a VOD Service Group.   VType(n)_Rate: The rate of the VType CODEC.   VType(n)_Session_Count: The variable refers to the number of current VType Sessions.   VType(n): Defines the CODEC type as one of the following HD-MPEG-2 @ 15 Mbps, SD-MPEG-2 @ 3.75 Mbps, HD-H.264 @ 7.5 Mbps, SD-H.264 @ 1.875 Mbps (the H.264 rates are only listed as an example)   VType(1): HD-MPEG-2 @ 15 Mbps   VType(2): SD-MPEG-2 @ 3.75 Mbps   VType(3): HD-H.264 @ 7.5 Mbps   VType(4): SD-H.264 @ 1.875 Mbps   . . .   . . .   Vtype(n): CODEC @ Mbps       

     An initial technique only accounts for MPEG-2 CODEC streams, it being understood that other CODEC and bit-rates can be defined in other versions. In some instances, the VType(1)_Threshold may be set to max bandwidth in a QAM minus the HD encode rate (e.g. 37.5-15=22.5). Once the bandwidth utilization within a QAM for a VOD Service Group reaches this threshold, the allocation technique will start stacking sessions on the least loaded QAM over the VType(1)_Threshold value. 
     By manipulating the VType(1)_Threshold value, the system&#39;s performance can be tuned based on the contention found in the system. By setting the VType(1)_Threshold to 37.5 Mbps (the max QAM bandwidth), the technique will allocate in a “least loaded” technique. 
     Since HD sessions require four times the amount of bandwidth when compared to SD sessions, there needs to be a way of limiting the number of HD sessions so that they cannot use all the bandwidth within a service group, which can result in denial of service. Limiting the number of HD sessions allows for the theoretical reservation of enough bandwidth to support SD VOD sessions. Conversely, limiting the number of SD allows for the theoretical reservation of enough bandwidth to support HD VOD sessions. 
     Reference should now be had to  FIG. 16 . Once the VType(1)_Threshold is reached across any QAM within a service group, the technique should start stacking sessions on the QAM channel that has passed VType(1)_Threshold. This method of allocating sessions will increase the probability of having the capacity to support an HD stream. This will allow a mix of 36 SD sessions and one HD session as shown in the figure. 
     In essence, the session requests that are provisioned below the VType(1)_Threshold are allocated across the QAMs within a VOD Service Group in a “least loaded” model and session requests that are allocated above the VType(1)_Threshold are allocated in a “most loaded” model. The following are exemplary steps to allocate bandwidth:
         1. Determine if the session setup request is either a VType(1)_Rate or VType(2)_Rate   2. Compare the VType(2)_Session_Limit or the VType(1)_Session_Limit to the new request type and then deny the session setup request if it equals the session limit type (QoS test) else   3. Check the bandwidth utilization across all the QAMs within a VOD Service Group and determine the lowest bandwidth utilization   4. If the lowest bandwidth utilization is below the HD_Threshold value on any QAM, then allocate the bandwidth on the least loaded QAM that has the requested capacity available (if the first QAM does not have the capacity try the next—QAM1→QAM2→QAM3→QAM4→QAM#n) else   5. Allocate the bandwidth on the most loaded QAM above the VType(1)_Threshold value QAM that has the requested capacity available (if the first QAM does not have the capacity try the next QAM—QAM1→QAM2→QAM3→QAM4→ . . . QAM#n)       

     By allocating sessions in the manner described above, the session allocation would, in one non-limiting example, appear as in  FIG. 17 . In this example:
         Session 1 through 24 are below the VType(1)_Threshold and are allocated in a “least loaded” model   25th SD session request is above the VType(1)_Threshold and is allocated on the first most loaded QAM channel. In this example, it would be on QAM1.   26th HD session request is above the VType(1)_Threshold and is allocated on the first QAM with enough available bandwidth to support the HD session. In this example, it would be on QAM2.   27th and 28th SD session requests are above the VType(1)_Threshold and are allocated on the first most loaded QAM channel. In this example, it would be on QAM1.   29th HD session request is above the VType(1)_Threshold and is allocated on the first QAM with enough available bandwidth to support the HD session. In this example, it would be on QAM3.   30th SD session request is above the VType(1)_Threshold and is allocated on the first most loaded QAM channel. In this example, it would be on QAM1.   31st, 32nd, 33rd and 34th SD session requests are above the VType(1)_Threshold and are allocated on the first most loaded QAM channel. In this example, it would be on QAM4.       

     Co-assigned United States Patent Application Publication No. 2003/0217365 of Caputo, the complete disclosure of which is expressly incorporated herein by reference in its entirety for all purposes, discloses a technique for providing programming content through a communications network having limited bandwidth. A specific carrier is assigned to deliver programming content of a program channel to a service area for a period, defined as a function of viewership of the program channel during that period. For example, the program channel is assigned the specific carrier during the time when it has a generally strong viewership. Otherwise, the program channel is assigned a carrier on an as needed basis, i.e., only when one or more subscribers in the service area request such a program channel. Viewing statistics are generated to identify viewership patterns or viewing habits of the subscribers in the service area with respect to a given program channel. In another embodiment, based on the viewing statistics, popular and unpopular programs, program elements, program lineups, program channels are identified on a temporal and/or regional basis. 
     Co-assigned United States Patent Application Publication No. 2007/0076728 of Rieger et al., the complete disclosure of which is expressly incorporated herein by reference in its entirety for all purposes, discloses a self-monitoring and optimizing network apparatus and methods. In an exemplary embodiment, the network comprises a broadcast switched digital architecture, and network bandwidth allocation to multiple digital program streams is performed by processing historical user tuning data, which is obtained directly from the subscriber&#39;s consumer premises equipment (e.g., DSTB). When an increase or decrease in bandwidth required to support certain programs is anticipated, network resource re-allocation is performed automatically by a software process running on the switching server. In this fashion, speculative but “intelligent” projections of bandwidth and program stream requirements can be made automatically by the server software, without operator intervention. The server also optionally dictates the optimal monitoring and data collection parameters to the DSTB. Historical data is stored on a CPE. 
     As noted, in some instances CPE  106  can include or be interconnected with a digital video recorder (DVR). One or more embodiments poll active DVRs and extract scheduled recordings. The extracted information can, in at least some instances, be sorted by service group and time. The data indicative of the scheduled recordings is then filtered to determine which scheduled recordings are SDV channels. In accordance with one or more embodiments, this information can be used to obtain an indication of SDV utilization per service group at a future time; for example, using a suitable correlation technique or the like. For example, in some instances, a factor could be applied to the data to yield an expected SDV usage per service group. In some instances, automated QAM allocation is applied based upon the expected SDV usage; for example, where QAM sharing is available between SDV, VOD and/or high-speed data (HSD) QAMs. Background reference is made to factor(s) determined in accordance with the aforementioned Publication No. 2007/0076728 of Rieger et al.; refer also to the section on SDV channel trending below. 
     Thus, one or more embodiments look at recordings that customers have scheduled with their DVRs. An entity such as an MSO obtains the information and determines whether any of the channels are SDV channels; if so, the information can be taken into account for scheduling purposes. For example, a determination can be made regarding possible blocking, or more general usage predictions, regarding the SDV service group. 
     In one or more embodiments, a component, such as a software component, communicates with a DVR within or coupled to CPE  106  (in a premises) and determines what recordings are scheduled via a polling process. In a non-limiting example, the component is a software component. Such software component may reside, for example, in head end  150  (or elsewhere, as long as in communication with a suitable scheduler). In some embodiments, the software component resides on MAS  104 A, which is capable of polling STBs or other components with DVR capability which are part of or are in communication with CPE  106 . 
     Thus, in one or more embodiments, software in head end  150  or elsewhere communicates with a DVR in the premises, and obtains a list of scheduled recordings. In some cases, the list of scheduled recordings is placed in a database, and a sort operation is conducted to determine the service group and the time. The sorted information is filtered to determine which channels are SDV channels. Filtering can be carried out, for example, using a database program such as Access® (registered mark of Microsoft Corporation, Redmond, Wash., USA), a spreadsheet such as Excel® (registered mark of Microsoft Corporation, Redmond, Wash., USA), automatic scripting, or the like. Other potentially useful database software includes Oracle® software (registered mark of Oracle International Corporation, 500 Oracle Parkway, Redwood City, Calif. 94065, USA); Informix® software (registered mark of International Business Machines Corporation, Armonk, N.Y., USA); and structured query language (SQL) software available from many sources, including Microsoft Corporation, Redmond, Wash., USA). 
     In one or more embodiments, as noted, a correlation is generated (for example, a factor is applied). This process could be carried out, for example, by collecting data pertaining to scheduled recordings over the course of time, measuring actual down-the-road usage, and developing a correlation between the two (other factors could be taken into account as well, such as time of day, to provide a multivariate correlation). Again, background reference is made to factor(s) determined in accordance with the aforementioned Publication No. 2007/0076728 of Rieger et al.; refer also to the section on SDV channel trending below. 
     Thus, one aspect of the invention pertains to the ability to extract data regarding SDV recordings scheduled for the future from the DVRs in or coupled to STBs  106 . This extracted data in turn can be used to forecast SDV usage and reserve bandwidth for the recordings. Another aspect of the invention involves increasing the amount of bandwidth to accommodate over-subscription; such aspect can be employed, for example, in situations when QAM sharing methods are available. Still another aspect involves reserving bandwidth (e.g., within service groups) for the scheduled recordings. 
     Once the factor or other correlation is available, a fairly accurate prediction of future SDV demand can be made based on the data regarding scheduled recordings and the QAMS can be allocated based on the expected usage. For example, if a potential blocking timeframe is noted, in systems where QAM sharing is available, more bandwidth could be allocated to SDV in response to noting the potential blocking time frame. In general, QAMs may be switched from one service to another to increase bandwidth as needed. Again, by way of example, a QAM might be switched from DOCSIS or VOD to SDV if high SDV demand is forecast. This could be implemented, by way of example and not limitation, using a DBWAD such as an SRM or GSRM  302 ; a suitable controller or the like could also be employed. 
     In some instances, the polling process employs conventional downstream and upstream data communication paths currently employed to communicate with the STB or other CPE  106 . 
     It will be appreciated that scheduled recordings are typically only part of the bandwidth that will be used for SDV in the future time of interest because some people will typically be watching in real time. This is one of the reasons why the correlation process is employed in one or more embodiments. In some instances, human agency may be involved in examining the data and developing the correlation. 
     The correlation can be employed for a variety of uses. For example, in some instances, sufficient bandwidth may be reserved in advance for material that a DVR is scheduled to record. In one or more embodiments, determine that a particular channel for which a recording is scheduled is a switched channel, and at a predetermined time (say, about ½ hour before the recording is scheduled to start), reserve bandwidth in the group for that recording (in essence, a reservation of bandwidth system). 
     One or more embodiments thus involve polling scheduled DVR recordings and correlating same to predict SDV usage. One or more embodiments advantageously do not require storing extraneous data on the STB, DVR, or other CPE. Thus, at least some embodiments of the invention are directed to polling and correlation of scheduled DVR recordings to predict SDV usage. In at least some cases, this is carried out without the use and/or storing of tuning or remote control data. Some embodiments provide bandwidth reservation. Sorting and/or filtering processes can be carried out on the raw data, in at least some cases. 
     SDV Channel Trending 
     A non-limiting example will now be provided regarding prediction of usage. Gather a particular period of time over several weeks for each Service Group (SG). As an example, use Saturday night from 8 pm to 9 pm for the past three weeks and gather the channels in Service Group 1 (SG1). 
     Note the following parameters: 
     Channel=x 
     Trended channel=tx 
     Schedule recorded channel=rx 
     Below is the exemplary channel usage pattern of SG1 per week on Saturday between 8 pm and 9 pm: 
     Week one SDV channel usage=a, b, c, d, e, f 
     Week two SDV channel usage=a, c, h, j, k, 
     Week three SDV channel usage=a, b, h, m, n 
     A trending pattern value can be developed and applied to each channel based on the number of times each channel was in use during the trended time: 
     Channel a=100% 
     Channel b, c, and h=66% 
     Channel d, e, f, j, k, m and n=33% 
     A trend can be created based on the information gathered from SG1 on Saturday between 8 pm and 9 pm. Five to six channels are expected to be used in SG1 based on the overall channels used during this time. In one or more embodiments, the forecast model uses the higher value so that sufficient capacity is available in the SG. Channel a was in use 100% of the time over the trended time period and therefore is expected to be used in week four and will take one of the six channel slots. Channels b, c, and h were used 66% of the time and these channels will take two to three slots. Channels d, e, f, j, k, m and n consumed two to three slots each week so it is expected that they will take two to three slots in week four. The forecast model will use three slots. Base on this trending pattern and the values applied to each channel slot, it is possible to trend week four usage as: 
     Week four=6 slots=ta(100%), t(66%), t(66%), t(33%), t(33%), t(33%) 
     Other trending formulas may be derived from gathering SDV channel usage information. The example above will be used for non-limiting illustrative purposes. 
     In one or more embodiments, DVR scheduled recordings are polled to determine which scheduled recording will require SDV channels. Once the recordings are polled, the information can be applied to the trended information. As an example, polling is completed and determines that there are three SDV channels that are scheduled to be recorded on the Saturday of week four between 8 pm and 9 pm. The channels are a, m, p. A more accurate forecast can now be created knowing this information. Week four&#39;s usage may, for example, be as depicted in  FIG. 20 . 
     Based on the forecasted information, it can be seen that one schedule recorded channel (a) is expected to be in SG1 because it was in all the previous weeks. One channel (m) will consume a 33% slot since it was in previous weeks and had a trending pattern value of 33% applied to it. There is one new channel (p) that will be used in SG1. Since the new channel was not trended then it will consume one additional slot. 
     Another aspect of one or more embodiments involves usage of the forecasted information to prevent SDV channel blocking. As an example, we will say that SG1 has six slots available. SG1 requires seven slots based on the forecasted information. Since there are not enough slots available, apply another set of slots to the SG prior to the expected blocking time by using QAM sharing methods. QAM sharing will allow a group of QAMs to be used for SDV, VOD and HSD as needed. 
     Still another aspect of one or more embodiments involves use of the polled schedule recording information and pre-configuration of the Service Group with the scheduled channels prior to the recording start time. This will insure that the schedule recording will not be blocked at the recording start time, but are available within the Service Group when required at the recording start time. In at least some cases, this aspect may be implemented separately from the prevention of channel blocking aspect mentioned in the previous paragraph. 
     Recapitulation 
     Reference should now be had to the flow chart of  FIG. 18 , which begins in step  1802 . Optional step  1804  is discussed below. Given the discussion thus far, it will be appreciated that, in general terms, an exemplary method, according to an aspect of the invention, includes the step  1806  of polling a plurality of digital video recorders (e.g., part of or coupled to CPE  106 ) to extract data indicative of recordings scheduled thereon. The polling is carried out over a video content network (e.g., switched digital HFC, FTTC, FTTH, or the like) by a component at a node in the video content network that is remote from the plurality of digital video recorders. A non-limiting example of such a component is a software module residing on a hardware server; by way of example and not limitation, MAS  104 A. However, the component could be on any of the other servers depicted herein or a new dedicated server. Non-limiting examples of a node remote from the plurality of digital video recorders include a head end or a hub or intermediate node. Note that in one or more embodiments, the polling is done through the set top communication paths from the DBDS (Digital Broadband Delivery System) system to the set top, creating a two-way communication path between the head end and the set top box. 
     Optional steps  1808 - 1812  are discussed below. 
     Step  1814  includes using at least a portion of the data to obtain a prediction of future switched digital video channel usage for the video content network. Step  1816  includes carrying out at least one network management activity on the video content network in response to the prediction of future switched digital video channel usage for the video content network. Processing continues at  1818 . 
     Note that in at least some instances, any one, some, or all of the steps may be carried out or otherwise facilitated by an MSO. 
     Non-limiting examples of network management activities include providing additional bandwidth to an oversubscribed group and/or instigating reservations for scheduled recordings. 
     In one or more embodiments, the prediction is not based on tuning data or remote control data. Use of data pertaining to scheduled recordings is advantageous since such data needs to be stored in the DVR in any case, and there is no need to maintain a log of remote control and/or tuning commands. 
     In one or more embodiments, the data indicative of the scheduled recordings includes data indicative of recordings for both switched digital video channels and channels other than the switched digital video channels (e.g., VOD, SD, HD). In such cases, in some instances, additional steps include step  1810 , sorting the data by service group and time to obtain sorted data; and step  1812 , filtering the sorted data to determine which of the scheduled recordings are for the switched digital video channels, to obtain filtered sorted data. In this aspect, the portion of the data which is used to obtain the prediction is the filtered sorted data, and the prediction of the future switched digital video channel usage is broken down by service group and time. For example, the data indicative of the scheduled recordings might include recordings scheduled for SDV channels, conventional broadcast channels, and so on, for multiple service groups, and for several days or even weeks into the future. In some instances, one might look into the future as far as the available program guide data; say, two weeks. In the sorting process, the data could be broken down into Service Group A, Service Group B, and so on, and within each Service Group, the data could be arranged by time slot, e.g., Thursday September 23 1-2 PM EDT; Saturday September 25 8-9 PM EDT, and so on. Of course, times could be in Greenwich Mean Time or otherwise. In the filtering process, recordings that were for SDV channels could be extracted and others discarded; for example, if Thursday September 23 1-2 PM EDT was for a broadcast channel it could be discarded while if Saturday September 25 8-9 PM EDT was for an SDV channel it could be extracted. Thus, the filtered, sorted data would include scheduled recordings from SDV channels broken down by Service Group and time (time being inclusive of day and month as well). 
     One non-limiting example of a network management activity, as per step  1816 , includes rededicating at least one network resource. By way of example and not limitation, such a network resource could be a QAM channel. The rededication could include making the QAM channel available for switched digital video usage (e.g., move a QAM channel from DOCSIS, VOD, or the like to SDV) or making the QAM channel available for other than switched digital video usage (e.g., move a QAM channel from SDV to DOCSIS, VOD, or the like). Of course, channels other than QAM channels could be used as appropriate for different technologies. 
     Such rededication (or other network management activity) could be carried out, for example, by a DBWAD  1001  such as a GSRM  302  or other SRM; a controller  212 ; a network management system  1110 , or the like. 
     Returning now to optional step  1808 , in some cases, the polling could also include placing the data into a database; in such instances, in at least some cases, the sorting and filtering steps  1810 ,  1812  can be carried out by a database management program operating on the database. The database could be stored, for example, in a memory on, and/or accessible to, the server on which the above-mentioned component was running. 
     Various techniques can be used to carry out the predicting step  1814 . Background reference is made to factor(s) determined in accordance with the aforementioned Publication No. 2007/0076728 of Rieger et al.; refer also to the section on SDV channel trending above. In some instances, prediction by correlation includes applying a factor to the number of scheduled recordings that are for the switched digital video channels at a given time for a given service group, to predict the corresponding required total switched digital video bandwidth required at the given time for the given service group. For example, Service Group A has 7 recordings scheduled for SDV channel 99 on Saturday September 25 8-9 PM EDT. Based upon a correlation of previous recording data and observed SDV usage, apply a factor of 3 to conclude that 21 users will wish to watch or record SDV channel 99 on Saturday September 25 8-9 PM EDT. The factor of “3” is purely a non-limiting illustration. The factor could vary by time of day or day of week; for example, a higher fraction of usage might be recordings during work hours, such that the factor at such times was “2.” The corresponding required total switched digital video bandwidth could be expressed in a variety of ways, such as Mbps, number of QAMs needed, number of expected viewers, and so on. The correlation should be other than a simple factor; for example, a least squares fit of any order could be used (considering, for example, scheduled recordings as a function of time). 
     Again, the correlation could be developed by carrying out step  1806  and optionally any one or more of steps  1808 - 1812  for a period of time, then comparing the stored data to actual SDV demand and applying least squares or other techniques to develop the correlation. 
     As noted, in some cases, the prediction mechanism varies by time of day or the like, i.e., recordings could be a higher fraction of total SDV usage in daytime when people are not home. Thus, in some instances, the prediction mechanism may itself change by service group, time of day, and so on. 
     Again considering step  1816 , another non-limiting example of a network management activity includes reserving bandwidth for at least one of the scheduled recordings. For example, a DBWAD  1001  such as a GSRM  302  or other SRM, a controller  212 , or the like could, for example, keep a table similar to  FIG. 5  wherein entries for SDV program material reserved for future recordation were maintained. 
     Furthermore, given the discussion thus far, it will be appreciated that, in general terms, an exemplary apparatus for use in connection with a video content network having a plurality of digital video recorders coupled thereto (e.g., as part of or connected to CPE  106 ), according to an aspect of the invention, includes a memory, and at least one processor, coupled to the memory (e.g., memory  1930  and processor  1920  as discussed below in connection with  FIG. 19 ). The apparatus could include a single server (e.g. MAS  104 A or other server) or several servers networked together (e.g. MAS  104 A or other server networked to GSRM  302  or other SRM, DBWAD  1001 , controller  212 , other server, or the like). The at least one processor is operative to carry out or otherwise facilitate any one, some, or all of the method steps described herein. In a preferred but non-limiting embodiment, steps  1806 - 1814  are carried out by MAS  104 A and step  1816  is carried out by GSRM  302 , it being understood that one or more different servers or other hardware modules, systems, or components could be employed in other cases. 
     System and Article of Manufacture Details 
     The invention can employ hardware or hardware and software aspects. Software includes but is not limited to firmware, resident software, microcode, etc. One or more embodiments of the invention or elements thereof can be implemented in the form of an article of manufacture including a machine readable medium that contains one or more programs which when executed implement such step(s); that is to say, a computer program product including a tangible computer readable recordable storage medium (or multiple such media) with computer usable program code configured to implement the method steps indicated, when run on one or more processors. Furthermore, one or more embodiments of the invention or elements thereof can be implemented in the form of an apparatus including a memory and at least one processor that is coupled to the memory and operative to perform, or facilitate performance of, exemplary method steps. 
     Yet further, in another aspect, one or more embodiments of the invention or elements thereof can be implemented in the form of means for carrying out one or more of the method steps described herein; the means can include (i) hardware module(s), (ii) software module(s) executing on one or more hardware processors, or (iii) a combination of hardware and software modules; any of (i)-(iii) implement the specific techniques set forth herein, and the software modules are stored in a tangible computer-readable recordable storage medium (or multiple such media). Appropriate interconnections via bus, network, and the like can also be included. 
       FIG. 19  is a block diagram of a system  1900  that can implement part or all of one or more aspects or processes of the present invention, processor  1920  of which is representative of processors associated with servers, clients, set top terminals, DBWAD, SRM, GSRM, controller  212 , MAS  104 A, and other elements with processing capability depicted in the other figures. In one or more embodiments, inventive steps are carried out by one or more of the processors in conjunction with one or more interconnecting network(s). 
     As shown in  FIG. 19 , memory  1930  configures the processor  1920  to implement one or more aspects of the methods, steps, and functions disclosed herein (collectively, shown as process  1980  in  FIG. 19 ). The memory  1930  could be distributed or local and the processor  1920  could be distributed or singular. In a non-limiting preferred embodiments, MAS  104 A has memory and one or more processors, and GSRM  302  has memory and one or more processors. The memory  1930  could be implemented as an electrical, magnetic or optical memory, or any combination of these or other types of storage devices. It should be noted that if distributed processors are employed, each distributed processor that makes up processor  1920  generally contains its own addressable memory space. It should also be noted that some or all of computer system  1900  can be incorporated into an application-specific or general-use integrated circuit. For example, one or more method steps could be implemented in hardware in an ASIC rather than using firmware. Display  1940  is representative of a variety of possible input/output devices (e.g., mice, keyboards, printers, etc.). 
     As is known in the art, part or all of one or more aspects of the methods and apparatus discussed herein may be distributed as an article of manufacture that itself includes a computer readable medium having computer readable code means embodied thereon. The computer readable program code means is operable, in conjunction with a computer system, to carry out all or some of the steps to perform the methods or create the apparatuses discussed herein. The computer readable medium may be a recordable medium (e.g., floppy disks, hard drives, compact disks, EEPROMs, or memory cards) or may be a transmission medium (e.g., a network including fiber-optics, the world-wide web, cables, or a wireless channel using time-division multiple access, code-division multiple access, or other radio-frequency channel). Any medium known or developed that can store information suitable for use with a computer system may be used. The computer-readable code means is any mechanism for allowing a computer to read instructions and data, such as magnetic variations on a magnetic medium or height variations on the surface of a compact disk. As used herein, a tangible computer-readable recordable storage medium is intended to encompass a recordable medium which stores instructions and/or data in a non-transitory manner, examples of which are set forth above, but is not intended to encompass a transmission medium or disembodied signal. 
     The computer systems and servers described herein each contain a memory that will configure associated processors to implement the methods, steps, and functions disclosed herein. Such methods, steps, and functions can be carried out, e.g., by processing capability on individual elements in the other figures, or by any combination thereof. The memories could be distributed or local and the processors could be distributed or singular. The memories could be implemented as an electrical, magnetic or optical memory, or any combination of these or other types of storage devices. Moreover, the term “memory” should be construed broadly enough to encompass any information able to be read from or written to an address in the addressable space accessed by an associated processor. With this definition, information on a network is still within a memory because the associated processor can retrieve the information from the network. 
     Thus, elements of one or more embodiments of the present invention can make use of computer technology with appropriate instructions to implement method steps described herein. 
     As used herein, including the claims, a “server” includes a physical data processing system (for example, system  1900  as shown in  FIG. 19 ) running a server program. It will be understood that such a physical server may or may not include a display, keyboard, or other input/output components. 
     Furthermore, it should be noted that any of the methods described herein can include an additional step of providing a system comprising distinct software modules embodied on one or more tangible computer readable storage media. All the modules (or any subset thereof) can be on the same medium, or each can be on a different medium, for example. The modules can include any or all of the components shown in the figures (e.g. modules/submodules for the controller, DBWAD, SRM/GSRM, MAS, set-top terminal, billing system server, to perform the method steps in  FIG. 18 , and so on). In some instances, a module for carrying out or otherwise facilitating step  1804  resides on component  152 ; a module for carrying out or otherwise facilitating steps one, some, or all of steps  1806 - 1814  resides on MAS  104 A; and a module for carrying out or otherwise facilitating step  1816  resides on a DBWAD, SRM, GSRM, controller  212 , or the like. The method steps can then be carried out using the distinct software modules of the system, as described above, executing on the one or more hardware processors. Further, a computer program product can include a tangible computer-readable recordable storage medium with code adapted to be executed to carry out one or more method steps described herein, including the provision of the system with the distinct software modules. In one or more embodiments, the code is stored in a non-transitory manner. 
     Non-limiting examples of languages that may be used include markup languages (e.g., hypertext markup language (HTML), extensible markup language (XML), standard generalized markup language (SGML), and the like), C/C++, assembly language, Pascal, Java, EBIF—Extended Binary Interchange Format language, UNIX shell scripts (for example, to generate information to supply to the GSRM), and the like. Note that EBIF would typically only be employed in connection with a set-top box. RTSP and/or RPC can be employed for interface protocols, for example. Furthermore, non-limiting examples of useful database software include Access® software (registered mark of Microsoft Corporation, Redmond, Wash., USA); Oracle® software (registered mark of Oracle International Corporation, 500 Oracle Parkway, Redwood City, Calif. 94065, USA); Informix® software (registered mark of International Business Machines Corporation, Armonk, N.Y., USA); and structured query language (SQL) software available from many sources, including Microsoft Corporation, Redmond, Wash., USA). 
     Accordingly, it will be appreciated that one or more embodiments of the invention can include a computer program including computer program code means adapted to perform one or all of the steps of any methods or claims set forth herein when such program is implemented on a processor, and that such program may be embodied on a tangible computer readable recordable storage medium. Further, one or more embodiments of the present invention can include a processor including code adapted to cause the processor to carry out one or more steps of methods or claims set forth herein, together with one or more apparatus elements or features as depicted and described herein. 
     System(s) have been described herein in a form in which various functions are performed by discrete functional blocks. However, any one or more of these functions could equally well be embodied in an arrangement in which the functions of any one or more of those blocks or indeed, all of the functions thereof, are realized, for example, by one or more appropriately programmed processors such as digital signal processors (DSPs). Thus, for example, switching unit  104  and modulator bank  106  (or any other blocks, components, sub-blocks, sub-components, modules and/or sub-modules) may be realized by one or more DSPs. A DSP typically comprises a combination of digital logic devices and other components, which may be a state machine or implemented with a dedicated microprocessor or micro-controller running a software program or having functions programmed in firmware. 
     Although illustrative embodiments of the present invention have been described herein with reference to the accompanying drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various other changes and modifications may be made by one skilled in the art without departing from the scope or spirit of the invention.