Patent Publication Number: US-6987734-B2

Title: Provision of digital data via multiple broadcasts

Description:
FIELD OF THE INVENTION 
     The present invention relates to broadcast of digital content, such as Internet accessible content, via wireless connections. 
     BACKGROUND OF THE INVENTION 
     In the decade that has recently passed, technologies for digital storage and transmission of data have revolutionized the national economy. Business and private homes are now increasingly connected to the Internet and other elements of the information infrastructure, using these connections for commerce, communication and leisure. 
     Initially, a large number of businesses and consumers obtained access to the Internet through dial-up connections through the telephone network, to an Internet service provider. Unfortunately, the communication speed of such a connection is currently limited to less than 56 kilobits per second (kbps). As applications of digital communication technologies have emerged, businesses and consumers have desired connections providing ever-greater communication speeds. In response to the resulting demand, high speed access technologies have been introduced, including digital subscriber line (DSL) services available through telephone utilities, digital cable services available through cable television companies, and digital satellite services using a digital satellite television network to deliver Internet content in response to requests from subscribers received over a standard telephone line connection. 
     While these high speed access technologies have been well received, each is available only to a limited number of customers. Particularly, DSL services are available only to those businesses and consumers in areas where telephone systems have been upgraded for digital operation. Digital cable service is available only to areas serviced by a cable television company that has made a similar investment in digital cable equipment. Digital satellite systems are theoretically available to every customer within the footprint of the transponders of the satellite; however, the satellite itself is a limited resource and thus can only service a limited number of subscribers. 
     There exists a need, therefore, for a methodology providing high speed access to digital content, that is available on a broad basis, particularly to those businesses and consumers that are not adequately serviced by existing technologies, such as businesses and consumers in rural areas. 
     SUMMARY OF THE INVENTION 
     Recently, the Advanced Television Standards Committee established standards for terrestrial digital transmission of television signals in the United States. Concurrently, Congress passed implementing legislation to allocate spectrum to existing holders of licenses from the Federal Communications Commission so that those licensees could commence digital television broadcasts of standard definition and ultimately high definition signals as the desired content evolves. 
     Unfortunately, at the present time, the vast majority of television content available to broadcasters is available only in standard definition, i.e., approximately 500 interlaced lines of resolution. Only a small amount of content available to broadcasters is in high definition format, i.e., 1000 interlaced or 500 progressive lines. As a consequence, the approximately 19 Mbps bandwidth signal produced on digital broadcast frequencies contains only about 12 Mbps of television signals, with the remaining bandwidth being consumed with “null packets” containing no television information. 
     As an inspiration of the present invention, it has been recognized that television broadcast transmitters are relatively ubiquitous within the United States, with most homes able to receive at least one and often several broadcasts. Furthermore, television broadcasts are not physically restrained by wiring; signals travel wirelessly in the RF spectrum. As a result, it has been recognized that the unused spectrum available to digital television broadcasters, can be a relatively wide bandwidth, nearly universally available path through which digital information may be delivered to consumers, providing a substitute or supplement to existing high speed digital access portals such as digital telephone or digital cable services. 
     Accordingly, one embodiment of the present invention relates to a method of providing Internet access through bandwidth available in broadcasted digital television signals such as the digital television signals produced by terrestrial broadcast towers. 
     One challenge in providing digital content through television broadcasts, is the need to dynamically allocate or provision the use of bandwidth among the customer base as the affiliated broadcasters change their use of bandwidth. For example, the broadcaster may initiate high definition programming, at which time the bandwidth available for Internet access is reduced and customers should be re-provisioned to other broadcasters, as possible. A similar issue is raised in the known provision of Internet access using digital satellite television broadcasts, in which case the overall bandwidth consumed at the satellite may change over time, and/or the bandwidth consumed at a given transponder at a satellite may change. 
     In accordance with another aspect of the present invention, principles of the present invention facilitate automatic provisioning of client usage among multiple broadcast origination points, such as among different terrestrial transmission towers or satellites, among transponders or channels on a given tower or satellite, or among other forms of multiple broadcast origination points. The provisioning dynamically and automatically equalizes load among those multiple broadcast points. In the specific embodiment that is disclosed, this provisioning is managed in part by the clients, thus providing dynamic, distributed management of spectrum allocation. 
     As noted, while the invention is described in the context of providing digital content via a plurality of terrestrial broadcast stations that are simultaneously transmitting digital television signals within allocated spectra for such signals, principles of this invention do not limit its application to use in conjunction with terrestrial television broadcast signals. For example, principles of the present invention may be applied to automatic provisioning of digital content among other terrestrial broadcast sources, such as cellular telephone towers having available bandwidth, analog or digital radio broadcasts having available bandwidth, satellite broadcast facilities such as the satellites operated by Hughes and currently used for its DirecTV and DirecPC services, and/or dedicated broadcast towers or satellites operating in an allocated spectrum and limited to broadcasting requested digital content. 
     It will be noted that satellite broadcasts typically utilize a multitude of transponders, oriented to serve different geographic areas, providing digital television or other digital signals in a frequency- and time-multiplexed manner; in applications of the principles of the present invention to such technology, the provisioning may occur among multiple satellites as well as between transponders or time- or frequency-multiplexed channels provided by a single satellite. 
     The above and other objects and advantages of the present invention shall be made apparent from the accompanying drawings and the description thereof. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with a general description of the invention given above, and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  illustrates the geographic positions of a client  10  and a plurality of broadcast towers from which the client may obtain Internet access, as well as the telephone and wireless connections that are established in accordance with principles of the present invention; 
         FIG. 2  illustrates a configuration in accordance with principles of the present invention, of a client personal computer connected to the telephone network, Internet network, central control system  19  and digital television broadcast stations at a number of digital broadcast origination points; 
         FIGS. 3A and 3B  are illustrations of tables maintained at the central control system  19  of  FIG. 2  relating to geographic regions and affiliates in those geographic regions; 
         FIGS. 3C and 3D  are illustrations of affiliate information maintained at client  10  of  FIG. 2  relating to reception quality obtained from each of several affiliates; 
         FIG. 4A  is an illustration of the format of the ATSC-compliant 19 Mbps packet stream broadcast by an affiliate; 
         FIGS. 4B and 4C  are, respectively, illustrations of region participant and affiliate loading beacons transmitted by affiliates; 
         FIG. 5A  is a flow chart of the sequence of events in the configuration of  FIG. 2  that occurs in initiation of an Internet connection in accordance with principles of the present invention; 
         FIG. 5B  is a flow chart of operations performed to obtain a suggested channel from the region support server in accordance with principles of the present invention; 
         FIG. 5C  is a flow chart of the sequence of events in the configuration of  FIG. 2  that occurs during use of an Internet connection in accordance with principles of the present invention; 
         FIG. 5D  is a flow chart of the sequence of events in the configuration of  FIG. 2  that occurs in response to an affiliate loading beacon, and 
         FIG. 5E  is a flow chart of the sequence of events in the configuration of  FIG. 2  that provides load balancing or provisioning between digital broadcast signals; 
         FIG. 5F  is a flow chart of steps taken upon loss of RF data by the client during operation of the system of FIG.  2 . 
     
    
    
     DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS 
     Turning to the Drawings, wherein like numbers denote like parts throughout the several views, a configuration in accordance with principles of the present invention can be explained. 
     Referring to  FIG. 1 , a typical arrangement of components in providing wireless Internet access can be explained. In the case illustrated in  FIG. 1 , a client for the service  10  is located at a private residence or business location unable to obtain high speed Internet access via cable or telephone connections. Client premises  10  is accessible to the Internet only through telephone dial-up connections via telephone lines  12  to an Internet service provider  14  and from there to the public Internet  16 . 
     Client  10 , in accordance with the principles of the present invention, obtains Internet access from digital broadcast signals originated by remote transmitters, such as digital television transmitters  18   a  and  18   b.  It can be seen in  FIG. 1 , that in accordance with the principles of the present invention, transmit towers are grouped into regions such as region  1   20   a  and region  2   20   b.  Within each region is a region control center  19   a  or  19   b  respectively, controlling the delivery of digital data to clients via transmission towers within that region. As can be seen, typically a plurality of transmission towers are included in each region, and are connected to a region control center  19  via high speed wireless or wired digital data connections. Each regional control center  19  is coupled via a high speed connection to the public Internet  16  whereby regional control center  19  may obtain Internet content for transmission to clients such as  10 , and interact with clients such as  10  to facilitate delivery of digital data content. 
     Referring to  FIG. 2 , details can be seen in the structures at regional control centers  19  and client  10 , as well as broadcast systems used by transmitters  18  within a region. At the premises of client  10  is a personal computer system or another computer system used by the client to access Internet content. Computer system  10  is illustrated as a stand-alone personal computer (PC), but may also be configured as a networked computer system including one or more client computers (e.g., desktop or PC-based computers, workstations, etc.) coupled together as a peer network using, e.g., Windows networking, and/or client computers and a server (e.g., a PC-based server, a minicomputer, a midrange computer, a mainframe computer, etc.), connected through a network. 
     Computer  10  operates under the control of an operating system, and executes various computer software applications, components, programs, objects, modules, etc. (e.g., networking software, an Internet protocol stack, the software described below, among others). Moreover, various applications, components, programs, objects, modules, etc. may also execute on one or more processors in another computer coupled to computer  10  via a network, e.g., in a distributed or client-server computing environment, whereby the processing required to implement the functions of a computer program may be allocated to multiple computers over a network. 
     In general, the routines executed to implement the embodiments of the invention, whether implemented as part of an operating system or a specific application, component, program, object, module or sequence of instructions will be referred to herein as “computer programs,” or simply “programs.” The computer programs typically comprise one or more instructions that are resident at various times in various computer memory and storage devices. When a program is read and executed by a processor, the program causes the computer to execute steps or elements embodying the various aspects of the invention. 
     Moreover, while the invention has and hereinafter will be described in the context of fully functioning computers and computer systems, those skilled in the art will appreciate that the various aspects and embodiments of the invention are performed via software and are capable of being distributed as a program product in a variety of forms. Further, the invention applies equally regardless of the particular type of signal bearing media used to actually carry out the distribution. Examples of signal bearing media include but are not limited to recordable type media such as volatile and non-volatile memory devices, floppy and other removable disks, hard disk drives, optical disks (e.g., CD-ROM&#39;s, DVD&#39;s, etc.), among others, and transmission-type media such as digital and analog communication links. 
     In addition, various programs described hereinafter may be identified based upon the application for which they are implemented in a specific embodiment of the invention. However, it should be appreciated that any particular program nomenclature that follows is used merely for convenience, and thus the invention should not be limited to use solely in any specific application identified and/or implied by such nomenclature. 
     Those skilled in the art will recognize that the exemplary configuration illustrated in  FIG. 1  is not intended to limit the present invention. Indeed, those skilled in the art will recognize that other alternative hardware and/or software configurations may be used without departing from the scope of the invention. 
     In the embodiment illustrated in  FIG. 1 , computer  10  may include: a central processing unit (CPU)  21 , a number of peripheral components such as a computer display  25  interfaced via a video card, a storage device such as a hard disk  23 , memory  22 , and various devices connected via input/output connections, such as a printer  24 , input devices, and others. 
     Computer  10  typically includes at least one processor  21 , but processor  21  may represent one or more processors (e.g., microprocessors). 
     Memory  22  may represent the random access memory (RAM) devices comprising the main storage of computer  10 , as well as any supplemental levels of memory, e.g., cache memories, non-volatile or backup memories (e.g., programmable or flash memories), read-only memories, etc. In addition, memory  22  may be considered to include memory storage physically located elsewhere in computer  10 , e.g., any cache memory in processor  21 , as well as any storage capacity used as a virtual memory. Data of particular interest that may be stored in memory  22  in accordance with the principles of the present invention, are a client channel viability table (CCVT) and an affiliate problem table (APT), each of which will be discussed below. 
     For interface with a user, computer  10  typically includes one or more input devices (e.g., keyboard  27 , pointing device such as mouse  26 , a trackball, a joystick, a touchpad, and/or a microphone, among others) and a display  25  (e.g., a CRT monitor, an LCD display panel, and/or a speaker, among others). It should be appreciated, however, that with some implementations of computers used in accordance with principles of the present invention, e.g., some server implementations, direct user input and output may not be supported by the computer, and interface with the computer may be implemented through a client computer or workstation networked with computer  30 . 
     For additional storage, computer  10  may also include one or more mass storage devices  23 . Exemplary storage devices  23  can include: a floppy or other removable disk drive, a hard disk drive, a direct access storage device (DASD), an optical drive (e.g., a CD drive, a DVD drive, etc.), and/or a tape drive, among others. 
     Furthermore, in a networked environment, computer  10  may include network interfacing equipment with one or more networks (e.g., a LAN, a WAN, a wireless network, and/or the Internet, among others) to permit the communication of information with other computers coupled to the network. It should be appreciated that computer  10  typically includes suitable analog and/or digital interfaces between processor  21  and each of components coupled thereto. 
     For carrying out access to Internet content in accordance with principles of the present invention, computer  10  includes a modem  30 , which is illustrated as an internal modem but may be an external modem or a shared modem available at a modem pool in a networked computer system. 
     Computer  10  further includes a digital television receiver card  32  for tuning digital television signals received from a suitable antenna  38  connected thereto. Digital television receiver card  32  is, again, illustrated as an internal card but may also be an external device or a device accessed via a computer network. Digital television receiver  32  may be an external television receiver with a high speed digital connection to CPU  21 , or preferably may be an expansion card for use in a personal computer such as the Digital Television Tuner Expansion Card available as the TerraCast DTA-100, from Broadlogic, Inc., 638 Gibraltar Court, Milpitas, Calif. 95035. 
     When used to obtain Internet content, computer system  10  connects via a dial-up (POTS) telephone connection through the public telephone network  34  to a dial-up server  36  located at an Internet Service Provider (ISP), establishing a point-to-point connection for Internet traffic, as is conventionally used for Internet access by consumers. ISP server  36  provides access to the public Internet  16  via a router or other connection established and maintained by ISP server  36 . Conventionally, a modem such as modem  30  is used in this manner for a bidirectional access to Internet content via the public telephone network and an Internet Service Provider (ISP). In accordance with the principles of the present invention, Internet content is also received via a digital television receiver (DTV) card  32  and incorporated into the personal computer at the client location. DTV receiver card  32  is used to receive digital television signals from one of the various television transmitters  18  that can be received at the premises of client  10 . 
     As will be explored in further detail below, to access Internet content from a third-party server  40 , CPU  21  delivers a request for this content via modem  30  in the public telephone network and ISP  36  through the public Internet to region control center  19 . In region control center  19 , the client&#39;s request is converted to a request directed to a third party server  40 . When content is returned from third party server  40 , region control center  19  then delivers the returned content to the broadcast digital television station currently being monitored by the client, so that the content will be transmitted back to the client for receipt by the client&#39;s digital television receiver  32 . 
     As seen in  FIG. 2 , region control center  19  includes three main components. The first component is a router  42  coupled to the public Internet  16  via high speed connection. Router  42  routes Internet traffic to and from the public Internet  16  and other connected sources and destinations based upon a routing table  44  internal to router  42 . Router  42  is of a configuration that is known throughout the public Internet  16 , which is widely populated with routers that route packets in accordance with the Internet protocol (IP) based upon routing tables. The Internet protocol defines a process in which routing tables and routers are updated, using a dynamic routing protocol. The routers receive packets containing routing information, that are exchanged amongst routers and describe connections accessible at each router. As explored in detail below, routing information packets are used to update the routing table  44  in router  42  as to properly route Internet content to clients via digital television stations at a region. Various protocols may be used for this interaction, such as RIP, RIP 2  or OSPF (open shortest path first). OSPF has the advantage that it may be used with a large number of clients. 
     Region control center  19  further includes a virtual private networking server  46  or a cluster of such servers which are used for establishing virtual private networks using Internet tunneling protocols, to client computer systems via the client&#39;s Internet server provider. Control information and identifications of content requested by a client, are delivered from the client to the regional control center, via the virtual private networking connection. 
     A third element at region control center  19  is a support server  48 . Support server  48  includes control information and monitors and controls operation of other elements of the region control center. Support server includes databases used in management of client Internet connections including a region table (RT) and a region participate table (RPT) which are detailed in  FIGS. 3A and 3B  below. 
     Support server  48  and router  42  are connected directly via wireless or wired high speed digital data connections to each broadcast television station within the region being controlled by the region control center  19 . Three such stations are illustrated in FIG.  2 . Station  50 - 1  is detailed so that the major operating components of a DTV station can be seen. Stations  50 - 2  and  50 - 3  are illustrated in schematic form. Each station  50  delivers a 19 Mbps digital television signal via a transmitter to a transmission tower  18 . This 19 Mbps digital signal incorporates digital television information in accordance with the Advanced Television Standards Committee (ATSC) formats. Further, this digital stream includes Internet content that has been selected and requested for delivery by clients in accordance with principles of the present invention. 
     As can be seen in the detail of station  50 - 1 , each broadcast DTV station incorporates an ATSC encoder  52  for producing a digital television stream conforming, e.g., to standard 310M at 19 Mpbs. This digital television stream is delivered to a encapsulator  54 , that has the purpose of encapsulating internet protocol information into moving picture expert group (MPEG) television information produced by ATSC encoders. Encapsulators that are suitable for use as encapsulator  54  are available from Skystream Networks of 455 DeGuigne Drive, Sunnyvale, Calif. 94085-3835. Further details on the operations performed by encapsulator  54  to encapsulate IP information into a MPEG stream will be discussed below with reference to FIG.  4 A. 
     Referring now to  FIG. 3A , details of the region table maintained by support server  48  can be explained. The region table includes information relating to the various regions that are available to clients in accordance with principles of the present invention. Each region is represented by an entry in region table of  FIG. 3A ; each entry includes the identifier for the region, the Internet protocol address for the virtual private networking server for that region, the IP address for the router for that region and the IP address for the support server for that region. 
     Referring now to  FIG. 3B , the format of the region participant table can be explained. The region participant table provides information for broadcasters that are participating in the broadcast of Internet content in accordance with the principles of the present invention for each region. Each entry in this table represents one transmission site that participates in the broadcasting system of the present invention. Each entry identifies the affiliate broadcaster using an identifier, as well as using call letters such as are typically used on digital television stations or radio stations. Additionally, an affiliate channel number to be used by a digital television tuner is provided. A channel packet identifier (PID) is also provided which can be used to identify those packets delivered by the affiliate that contain Internet protocol information. The affiliate is also associated with the identifier for the region within which the affiliate participates. And finally, the table provides the Internet protocol address of the encapsulator used by the affiliate. The information in the region table and the region participate table are sufficient for the region control center to manage and communicate with each affiliate for a region. 
     Referring to  FIG. 3C , the client channel viability table established by a client computer system can be explained. As is detailed below, the client channel viability table is assembled by the client computer system  10 , to store all relevant information regarding channels that are potentially accessible to the client. Each entry in the client channel viability table is representative of a channel potentially receivable by the client. Within an entry, a channel is identified by a channel number. The table stores the signal strength of the channel during those periods when the channel is received, and the error rate, i.e., the number of uncorrectable packets received on the channel. Each channel is flagged as usable or not usable within the client channel viability table, in a manner that is discussed in further detail below. Each channel is also associated with the PID used by that channel in the encapsulated Internet protocol information. Finally, each channel is associated with the Internet protocol address of the virtual private networking server at the region control center to which the channel is connected. The client channel viability table is used in the manner described below to select and manage the selection of a particular channel through which to receive Internet protocol information. The usability of the currently tuned channel for this purpose is regularly assessed, and the information that is gathered is stored in an affiliate problem table. 
     Referring to  FIG. 3D , the affiliate problem table includes an entry for each affiliate that is potentially receivable by a client. The affiliate is identified by the same affiliate ID used in the region participant table of FIG.  3 B. In the affiliate problem table, fields are used to store the date and time when a problem was encountered receiving digital data from a channel. Two fields are provided to store date and time information for two encountered problems. As explored in detail below, channels are disqualified from use for Internet routing when more than two problems have been encountered in a short time period as is identified in the fields in the affiliate problem table. Based upon an analysis of this kind, a further field in the affiliate problem table is a status bit that may be set to 1 or 0 to indicate whether the affiliate is available for use. Finally, a last field in the affiliate problem table is used to identify the number of times that a transmission problem has occurred with the affiliate. This count is used for a long term evaluation of affiliates that have had reception problems. Use of the client channel viability table and affiliate problem table will be explored in greater detailed below in connection with  FIGS. 5E and 5F . 
     Referring now to  FIG. 4A , the format of the ATSC compatible 19 Mbps stream can be discussed. As seen in  FIG. 4A , the transmitted stream of data comprises a sequence of 188 byte packets, each of which incorporates a header and a payload of data. The header for each packet includes a packet identifier PID field that identifies the type of packet that is being transmitted. Notably, in a typical ATSC compatible transmission the transmitted packets predominantly include video and audio data packets and null packets that do not deliver any data. The ATSC compatible receiver evaluates each packet as received and, based upon the PID incorporated into the packet, determines the type of data and how it is to be delivered and/or processed. As noted above, transmissions of digital content to clients that has, e.g., been retrieved from an Internet source, is associated with a PID that is currently not used in ATSC compliant data transmissions. This PID is recognized by the ATSC compatible receiver, which in turn delivers the data content in the packet to the software described below which determines whether the data content is intended for client computer  10  and, if so, de-encrypts the data and returns it to the requesting application. 
     In addition to providing Internet protocol information requested by clients, region control system  19  causes additional beacons to be transmitted by each affiliated transmitting station. Referring to  FIG. 4B , the first beacon, known as a region participant beacon, delivers information on all regions and all affiliates in all regions that are provided in accordance with the principles of the present invention. This beacon takes the form of a packet having a header and a sequence of entries for regions and a sequence of entries for affiliates in those regions. The header for the packet includes a field identifying the packet type, followed by a region identifier for the region within which the beacon is being transmitted. Subsequently in the header, the number of regions identified by the beacon and the number of affiliates identified by the beacon are provided. This information in the header permits the remaining information to be correctly parsed and identified by client computer systems that receive the beacon. 
     After the header, the first section of the beacon includes a sequence of entries, one corresponding to each region and virtual private network for that region. Each entry includes the identifier of the region, the Internet protocol (IP) address for the virtual private networking server for the region, the IP address for the router for the region and the IP address for the support server for the region. 
     After the sequence of region entries, the beacon of  FIG. 4B  includes a sequence of affiliate entries, one for each affiliate for which information is provided. Each affiliate entry includes an identifier for an affiliate, as well as call letters of the affiliate, followed by the affiliate&#39;s channel number, the packet identifier PID used for Internet content transmitted by the affiliate, the region identifier for the region to which the affiliate belongs, and the IP address of the encapsulator being used by the affiliate. 
     It will be appreciated that the beacon illustrated in  FIG. 4B  includes sufficient information to assemble the complete copy of the region participant table and the region table shown in  FIGS. 3A and 3B . Thus, a client upon receipt of this beacon may assemble sufficient information to identify each of the regions and each of the affiliates in each region that are providing Internet protocol content in accordance with the principles of the present invention. 
     Referring now to  FIG. 4C , a second beacon signal that is transmitted from each of the transmitters can be explained. This beacon signal, known as an affiliate loading beacon, provides loading information for each of the transmitting stations identified in the beacon. Affiliate loading information is provided to clients so that clients may perform a load balancing algorithm described in detail below to choose an appropriate affiliate to use in receiving Internet protocol information. 
     The affiliate loading beacon includes a header, and a sequence of fields, each associated with an affiliate for which loading information is provided. The header includes a type identifier identifying the beacon as an affiliate loading beacon, followed by a region identifier for the region within which the affiliate loading is being reported. Thereafter, the header identifies a number of affiliates for which loading information is being identified. Finally, the header of the affiliate loading beacon identifies a lower and an upper connection number. As is explained in more detail below, these connection numbers are used to identify a subset of the clients to whom a particular beacon is to be directed. Only those clients whose connections fit within the range of the lower and upper connection number will respond to loading information to select potentially different transmitters for receiving Internet protocol information. It will be appreciated that the range between the lower connection number and the upper connection number may be adjusted by the region control system to carefully control the number of client computer systems that are reallocating their use of transmitters between one transmitter and another. By transmitting a beacon having a connection number range that is suitably chosen, the load amongst the transmitting stations may be well balanced without creating an excessive amount of channel swapping by client computer systems. 
     Following the header of the affiliate loading beacon, are a number of entries each associated with an affiliate. Within these affiliate loading entries, an affiliate is identified by its ID, and the loading of the affiliate is identified through a null packet count and special action bits. The null packet count for an affiliate reflects the number of null packets that the affiliate is transmitting at the present time period. This null packet count is thus a representation of the loading of the affiliate, with higher null packet counts reflecting lower load levels of an affiliate. It will be noted that the null packets count included in the affiliate loading beacon is a “represented” null packet count. In some instances, an affiliate may wish to reserve a certain bandwidth for use in other services. In this case, the null packet count of the affiliate may represent as available, will be less than the actual null packet count being broadcast by the affiliate, so as to reserve bandwidth for other applications. 
     The special action bits transmitted with the affiliate loading information, may have a variety of functions for performing special processing. As one example, the special action bit may be used as a vacate bit to direct all clients receivers to vacate the use of the transmission band for Internet protocol information. The vacate bit of this kind may be used to clear bandwidths when a television broadcaster is, for example, transitioning from a standard definition broadcast to a high definition broadcast. The special action bits may also be used to designate specific broadcast types, such as virus signature updates, streaming video of interest to multiple clients, or other forms of content that may be identified as currently available from a transmitter. 
     Referring now to  FIGS. 5A through 5F , specific processes followed by the system illustrated in  FIG. 2  can be more clearly understood.  FIG. 5A  describes the initialization of the client computer system to utilize Internet access via digital transmissions in accordance with the principles of the present invention. In a first step  100 , the client computer system determines whether an Internet connection via an Internet service provider (dial up modem link) is in place. If no connection is in place, then in step  102 , the operating system libraries are activated to establish a low bandwidth connection, for example, using a modem and a telephone as discussed above. After a connection to the Internet has been established, in step  104  the client&#39;s telephone number is obtained, and then used in step  106  to obtain a rough estimate of the latitude and longitude of the clients premises. This longitude and latitude estimate, is then used in step  108  to determine the client&#39;s location relative to the regions illustrated in FIG.  1 . 
     If the longitude and latitude computed for step  108  is not within the client&#39;s home region, then in step  110  it is determined whether the client has subscribed to a roaming service. If not, then the client is prompted to verify the telephone number in step  112 . If the received telephone number is the same in step  114 , it is determined that the user is in fact roaming away the client&#39;s home region. In this case, in step  116  the user is asked to consent to paying a surcharge for roaming. If the user is willing to pay for roaming, then in step  118  the user is subscribed to the roaming service and processing continues. If the user is unwilling to pay for roaming in step  116 , then no broadcast service is available and the user is so notified in step  121 . In such a case, the client&#39;s Internet communications will all be performed via the bidirectional low bandwidth connection established, e.g., using the telephone line and Internet service provider. 
     If the user is authorized roaming or if the user is in his home region, processing will arrive at step  120 . In step  120 , the user of the client computer system is prompted for a user name and password, which are then used to login into the identified local region support server via the low bandwidth, e.g., telephone IP, connection. Communications with the region support server permit the client computer system to obtain the content of the region participant table and store this content or update previously stored content. The client computer system thereby obtains specific information regarding the location of transmitters within the locally available radio spectrum. Accordingly, in step  122 , the client computer system tests each channel identified in the participant table to determine whether the channel is reliably received by the client computer system. As channels are evaluated, the client computer system constructs the channel viability table of  FIG. 3C , by storing for each channel a signal strength measure as well as error rate measure. The channel PID and VPN IP address are available from the region participant table that was obtained in step  120  from the local region support server. 
     After step  122 , a channel viability table has been constructed for each channel in the local region. In step  124 , those channels that have been identified as viable, i.e., as having a sufficiently low error rate and sufficiently high signal strength, are reported to the user of the client computer system. This permits the user to assess whether the client computer system is receiving those channels that should be receivable at the client&#39;s current location. If some channels are not being effectively received, the user may wish to adjust the antenna associated with the DTV receiver card. To allow this, in step  126  the user is asked whether the user wishes to adjust the antenna. If so, then in step  128  channel information is made available to the user so that the user may view this information and adjust the DTV antenna being used by the DTV receiver card. After the user completes adjustments of the antenna, processing returns to step  122  to retest each potentially available channel and rebuild the channel viability table. 
     Once the user is satisfied with the channels that have been identified through the testing of step  122 , processing proceeds from step  126  to step  130  in which it is determined whether any viable channels have been found for use in IP transmissions. If not, then no broadcast service is available and processing terminates at step  121 . If viable channels are found in step  130 , then processing continues to step  132  to obtain a suggested channel from the regional support server using the process of FIG.  5 B. 
     Referring now to  FIG. 5B , the process of obtaining a suggested channel from the region support server can be explained. In a first step  134  the viable channel information is forwarded from the client computer system to the region support server over a previously established connection. This permits the region support server to utilize viable channel information and load information, available only to the region support server when the process of  FIG. 5B  is performed, to identify an appropriate channel for use by the client computer system. Region support server thus determines an appropriate channel to be used by client computer system and retrieves an affiliate ID number for the selected channel and generates a connection number. As noted above, connection numbers are assigned to each client utilizing the digital broadcast system, so that load balancing activities may be directed to particular clients or ranges of clients. 
     The affiliate identifier and connection number are delivered, in step  136 , to the client computer system. Thereafter, in step  138 , client computer system causes its digital television receiver card to tune to the channel of the affiliate identified by the region support server. Thereafter in step  140 , the initialization of the client connection continues, specifically, routing information is delivered to the router at the region central controller. This may be done in a variety of ways; in the illustrated example the region support server delivers a routing information packet notification to the router at the region central control. Alternatively, the client might generate a routing information packet and deliver the packet to the router. Regardless of how it is generated, the routing information packet causes the router to update its routing table so that packets directed to the client computer system are directed to the appropriate one of the digital broadcast transmitters for the local region. Within the client, in step  142 , a software interrupt is enabled, to watch the data flow so as to identify failures of the RF transmission and take an appropriate action as detailed below with reference to FIG.  5 F. 
     After these initializations are completed, the client computer system then logs into the region virtual private networking server to establish a virtual private network which may be then later used in obtaining Internet content through the process described with reference to FIG.  5 C. 
     Referring now to  FIG. 5C , the interaction of the client computer system and region central controller for providing Internet access to the client, can be described in further detail. The process of obtaining Internet access at a client begins when a request for Internet content is delivered from an application on the client computer system, through the operating system of the client computer system, to the virtual private networking service active on the client computer system. In a first step of processing this request, step  152 , the request is evaluated to determine the port number to which the request is directed. Certain kinds of requests, identifiable by their port number, do not utilize the broadcast Internet access provided through the DTV transmission towers in accordance with the principles of the present invention. Specifically, email, domain name service (DNS) requests, and telnet transactions, as identified by the ports to which they are directed, are examples of types of access that are not processed through the virtual private network connecting the client computer system to the region central controller. 
     For email, DNS, telnet and other disqualified transactions, processing proceeds to step  154  in which the request is delivered to the client Internet service provider without tunneling. A response is then received directly from the Internet service provider as is done in normal dial up Internet access using the Internet service provider. The received response in step  160  is then delivered to the requesting application. 
     Those forms of Internet access that do utilize the digital broadcast system of the present invention proceed from step  152  to step  162 . Requests that use the digital broadcast system may be FTP or HTTP requests or others. These requests are delivered to the virtual private networking server for the local region, using VPN tunneling in accordance with known virtual private networking standards. When the request is delivered to the virtual private networking server, it is delivered in the form of encrypted packets addressed to the public IP address of the virtual private networking server (step  164 ). In step  166 , the virtual private networking server establishes a network address translation so that it may deliver the received request via the region router to the requested external address of a third party server from which Internet content is requested. The request is delivered to the third party server using the Internet protocol address and port that are selected for the network address translation from the routee&#39;s external pool of addresses and ports. 
     In step  168 , responding to step  166 , the external server ultimately responds to the request from the VPN server. This response comes in the form of one or more packets identified as from the desired external IP address and delivered to the routers external IP address and port that were selected from the routers external pool for network address translation. In step  170 , the router applies network address translation to transfer the received response to the virtual private networking server. Thereafter, in step  172 , the virtual private networking server generates an encrypted Internet protocol packet or packets, directed to the public Internet protocol address of the requesting client and identifying the VPN server as the packet source. In step  174 , these encrypted Internet protocol packets are delivered to the region router which uses its current routing table to select one of the affiliates and forward the encrypted Internet protocol packets to that affiliate. 
     It will be appreciated that the routing table in the router at the central control system is updated with routing information packets each time a client “changes the channel”, i.e., selects a different DTV transmitter from which to receive Internet content transmissions. Therefore, the routing table will always accurately reflect the appropriate transmitter to which client requested content should be forwarded. In step  176 , the packets forwarded by the region router are incorporated into the digital television stream in the manner discussed above with reference to FIG.  4 A. 
     Thereafter, in step  178 , the client will identify the digital television packets containing Internet content from their packet identifier and will further identify Internet protocol packets directed to the clients computer from the Internet protocol address included in those packets. 
     In step  180 , the clients virtual private networking service, upon receiving the content from the digital television receiver card, will decrypt the packet(s) and deliver the content thereof to the requesting application. It will be appreciated that the speed at which content may be delivered to the client computer system via direct digital transmission can be substantially faster than is available from dial up telephone connections for the reason that all digital connections in the path of the returning Internet content are high speed connections. 
     As noted above, the client computer system establishes a software interrupt upon initializing for reception of Internet content. This software interrupt is activated each time a new affiliate loading beacon such as illustrated in  FIG. 4C , is received by the digital television receiver card of the client computer system. After receiving such a beacon in step  190 , in step  192  the beacon is evaluated to update the usability flags in the channel viability table of  FIG. 3C , based upon the special action bits of the affiliate loading beacon. Thus, for example, if the affiliate loading beacon includes special action bits requesting all client computer systems for vacate an affiliate channel, this data will be used to update the usability flags stored at the client computer systems so that client computer systems will no longer select those channels for use. In step  194 , the null packet counts provided in the affiliate beacon are also stored by the client computer system to be used in later evaluation of the load of affiliates, if and when it is necessary to “change the channel” to another DTV transmitter from which the client can receive digital transmissions. After storing this data, in step  196  the client computer system determines whether the client&#39;s connection number falls within the connection number range of the affiliate loading beacon. If so, then in step  198  the load balancing procedure of the client computer system is initiated, as described further below with reference to FIG.  5 E. If the client computer systems connection number is not in the connection number range of the loading beacon, processing continues from step  196  to step  200  in which the client computer system determines whether the vacate bit in the affiliate loading beacon is set, for the affiliate currently being used by the client computer system. If so, the client computer systems must immediately select a new channel for use in receiving digital transmission of Internet content. (Clients unable to receive any other transmission, may be allowed to remain on a channel at the discretion of the affiliate or control system.) Accordingly, in this case, processing begins again to step  198  to initiate load balancing. After load balancing, or if neither of the conditions of step  196  or step  200  are met, the processing of the affiliate loading beacon is completed. 
     Referring now to  FIG. 5E , the process for load balancing performed by a client computer system can be elaborated. After load balancing is initiated (step  210 ), in step  212  the null packet counts most recently received in an affiliate loading beacon are reviewed, as well as the stored affiliate usability information, to determine which channel is available for use. This process involves searching for a channel that is not only usable and no disqualified from use based upon prior problems, but also has the largest null packet count, as previously identified in an affiliate loading beacon. When a candidate channel is found, processing proceeds to step  214  in which the client computer system waits for a random timeout period of between 0-120 seconds. This timeout period insures that client computer systems will not all simultaneously change channels and thus radically change the loading being established by the region control center. At the end of this timeout period, in step  216 , the client computer system switches to the selected new channel, by providing an appropriate instruction to the digital television receiver card. Next, in step  218  it is determined whether data is receivable from the newly selected channel. If so, then processing continues to step  220  in which a new routing information packet is delivered to the regional router, as described above, so as to redirect all traffic for the client computer system to the new affiliate that has been selected by the client. 
     If the newly selected channel is not producing receivable data in step  218 , then in step  222 , the newly selected channel is designated as unusable in the affiliate viability table stored by the client computer system. Thereafter in step  224  client computer system determines whether there are any other usable channels identified in the viability table. If so, processing returns to step  212  to evaluate those other channels. 
     If there are no usable channels in step  224  or if there are no usable channels in step  212 , processing arrives at step  226 . In step  226 , the channels identified in the viability table and affiliate problem table are accessed to identify which of those channels have had problems prior to the most recent 24 hours. This step is taken so that channels which have had previous difficulties, and thus have been designated as unusable, are not permanently identified as unusable but can be reevaluated after a 24-hour period. 
     If there is a channel in the affiliate problem table having problems that are not from the most recent 24 hours, then in step  228  the client computer system switches to the channel. In step  230 , the client computer system determines whether data can be received from the selected channel. If so, then in step  232 , the affiliate problem table is updated to remove the problem indications, selected channel is identified as usable, and processing continues to step  220  to issue a request of the virtual private networking server to redirect traffic to the newly selected affiliate. 
     If in step  230  data is not found to be receivable from a channel, then that channel is marked as having problems at the current time in the affiliate problem table and processing returns to step  226  to attempt to identify another channel which may be evaluated to determine whether previous problems have been resolved. If no channels have been successfully identified in step  226 , ultimately processing will proceed to step  234  to which the user the warned that there are no usable channels available at the present time. (As noted above, clients only able to receive one channel may be permitted to use that channel even if the vacate bit for the channel is set.) If no service is available, in step  236  the virtual private networking service will be discontinued so that all Internet access proceeds through the low speed (dial up) connection that was established previously. 
     Referring now to  FIG. 5F , as noted above, a software interrupt is established during initialization of the client. This interrupt monitors the received RF data stream, so that loss of the RF data transmission from the digital television station can be immediately identified. When this occurs in step  240 , immediately in step  242  the date and time in which the problem occurred is stored in the affiliate problem table, associated with the current affiliate station. Thereafter in step  244 , it is evaluated whether the RF data stream has been connected preceding three hours. This is an attempt to measure whether the problems are recurring or relatively infrequent. In step  246 , if data has been lost more than three times in the last three hours, then processing proceeds to  FIG. 5B  to obtain a new suggested channel from the region support server. The region support server is enlisted to suggest a new channel for the reason that the recurring recent problems may have caused the client computer system to fail to receive a channel loading beacon, and so may lack the data needed to select an appropriate channel. If data has not been lost more than three times in the last three hours, then the difficulties with the current channel are not particularly chronic. In this case, load balancing is initiated in step  248  by proceeding directly to  FIG. 5E  to select a channel which can be used for further Internet access. 
     While the present invention has been illustrated by a description of various embodiments and while these embodiments have been described in considerable detail, it is not the intention of the applicants to restrict or in any way limit the scope of the appended claims to such detail. Additional advantages and modifications will readily appear to those skilled in the art. The invention in its broader aspects is therefore not limited to the specific details, representative apparatus and method, and illustrative example shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of applicant&#39;s general inventive concept.