Untitled record

DESCRIPTIVE MEMORY

OF THE

PATENT OF INVENTION

REFERRING TO:

"A METHOD FOR DISTRIBUTING INFORMATION THROUGH AN INTERACTIVE INFORMATION DISTRIBUTION PROVISION"

REQUESTED BY:

DIVA SYSTEMS CORPORATION

ADDRESSED IN:

333 Raven Swood Avenue Building 203, Menlo Park. California 94025 UNITED STATES OF AMERICA

FOR THE TERM OF 20 YEARS

<img file="AR010689A1_D0001.tif" />

one. Scope of the invention.

The present invention relates to a method for distributing information through an interactive information distribution arrangement and preferably relates to an arrangement and method of interactive information distribution, such as video, audio, libraries, interactive games and the like, to One or more subscribers. More particularly, the invention relates to a system for establishing a multi-channel communicative connection between the fixed top terminal of a subscriber and a service provider and then for handling the communications necessary to send interactive information services to the subscriber (s) (s)

two. Description of Technical Background.

Recent advances in digital signal processing techniques, and in particular, advances in digital compression techniques, have resulted in many proposals for new digital services to a subscriber's home via existing telephone and coaxial cable networks. For example, provision has been made to provide subscribers of hundreds of cable television channels by compressing digital information, digital video, compressed digital video transmission over conventional coaxial cable television channels, and subsequent video decompression. in the fixed top terminal of the subscriber. Another application proposed for this technology is a video-order system, in which a subscriber communicates directly with a video service provider, via telephone line, to request a particular video program from a video library, and the program of requested video is // r c-z'i &lt;·.!

// E? / 1-vJü i, .. C - \\ &lt;3, \ · —fa / 'route to the subscriber's home via telephone line or via the Ycäh ^ esL £ .oaxjal, e's

_.NPL of cable television, for immediate viewing.

However, these current video-on-demand video systems are not truly interactive systems, in which a subscriber can selectively access a large audio, video or information library and control the presentation of the requested information in real time, as when a video program is used using a VCR. Most of the systems currently available have a simple control interface, which allows subscribers to only request information, without any other control over the presentation of information. Other more sophisticated systems have a control interface that contains more complex instructions, such as start, stop, pause, fast forward and rewind, to allow a rudimentary control of the presentation of information. However, these systems use conventional information routing and signaling networks, which are relatively slow to react to instructions, for example, the latency between the moment an interactive function is requested and the moment it becomes effective. It is extremely long.

Also, the fixed upper terminals used by these systems contain a complex and expensive electronics in order to facilitate the processing of complex instructions. In addition, these systems use a conventional cable television network architecture, in which a central information server transmits information to a plurality of header systems and subsystems that in turn propagate several subsets of the information to an individual fixed upper terminal. or to multiple fixed upper terminals. In such systems, the servers perform many of the control functions and, therefore, the latency that is produced by sending control instructions through the end 2 paîentebrons533-002 / diva /

<img file="AR010689A1_D0002.tif" />

Server header is substantial.

Throughout, there is a need in the industry for an interactive information distribution system that offers real-time interaction (with a relatively short latency) between the subscriber and the service provider at any time during the presentation of the requested information .

SUMMARY OF THE INVENTION

The disadvantages associated so far with the prior art are overcome by the present invention. The present invention is a system for distributing information services interactively. The system contains an information server, a video session manager, a bi-directional cable transport network, and subscriber equipment (for example, a fixed top terminal, an input device, and an output device) .

The system uses three independent communication channels to facilitate the distribution and interactive control of the information distribution process. Specifically, an information channel propagates program information and a command channel propagates control information from the information provider to the subscriber's equipment, and a subsequent channel propagates control and command information from the subscriber's equipment to the service provider. The information channel can also be used to transport control information to the subscriber's equipment. Consequently, the service provider sends selection menus to the subscriber's equipment through command and / or information channels, so that the subscriber can choose a particular program.

The order of the chosen program passes through the channel after the service provider. The service provider then sends the program through the information channel for display on the subscriber's equipment. 3 patebrons533-002 / diva /, \

The subscriber can manipulate the presentation (for example, fast forward, pause, rewind, make derivations based on the context, etc.) by means of instructions sent from the subscriber's equipment to the service provider's equipment.

More specifically, the server provides a video session manager with a plurality of program streams that in general conform to the MPEG-2 transport protocol (Group of Experts on Animated Movies). Program streams are generated using a common, high-precision clock signal (synchronization clock), such that the information in the plurality of streams is synchronous. The video session manager interacts with the server to request certain streams of information programs in response to subscribers' requests. Once a subscriber requests the use of the service provider's browser to facilitate the selection of the viewable programming, the video session manager opens a “session” for a given subscriber and sends the requested program streams through the network of cable transport to the subscriber's fixed top terminal, via information channel.

In order for the subscriber to have interactive control in real time of the presentation of the information, the subscriber, through his input device (remote control) can request, start, stop, fast forward, rewind, pause and make derivations to and from any stream of information that is resident in the server subsystem.

In itself, the system of the present invention offers the user all the interactive commands that normally exist in a conventional VCR. Additionally, the user can open multiple sessions, so that multiple streams of information can be started and stopped and controlled interactively at any time. Said 4 patebrons533-002 / diva /

<img file="AR010689A1_D0003.tif" />

interaction is facilitated by the system since the system &lt;

from end to end. That is, the server provides the synchronization clock to which all the subsystems of the invention are synchronized. System synchronization extends to the cable transport network and the subscriber's fixed top terminal.

In particular, the synchronization clock is used by the video session manager to modulate all the data streams, so that each stream transmitted is synchronized with other streams. In addition, the fixed upper terminals recover the timing of the synchronized information bits within the received current; in this way, the fixed upper terminals are also synchronized to the synchronization clock. In itself, when a subscriber changes from one program to another, there is no re-synchronization delay before the other program is available for viewing. Consequently, the latency between the moment an order is entered and the moment it is implemented is relatively short. That way, a subscriber can have multiple sessions open and jump from one to another without substantial delay after each session change.

To reduce the cost associated with the transmission and presentation of each program stream, the system of the present invention avoids encrypting all the information sent to the fixed upper terminals. System security, without encryption, is given by numbers of identification (PID) assigned and altered at random. Specifically, when a session begins at the request of a subscriber, the fixed upper terminal is assigned a unique session number. In addition, the fixed upper terminal has an identification number (TID) assigned. This TID is compared with the TID stored in the system, in order to confirm the identity of the user. Periodically, the TID numbers are paìentebrons533-002 / diva /

<img file="AR010689A1_D0004.tif" />

update on a random basis to ensure system security. The requested information is transmitted in multiplex on an information channel, for example, ten streams of 2.6 Mbit / sec. of data are transported by a single information channel to a plurality of fixed upper terminals (a neighborhood). A neighborhood can be served by more than one channel to further increase transmission flexibility. For example, the terminals are dynamically assigned to the channels, so that 10 terminals can share a channel simultaneously or three terminals can receive 5.2 Mbit / sec of data, etc. Consequently, any combination of data rates is allowed and the information rate of a given subscriber depends on the information requested. Some programs, such as basketball games, may require a large transmission bandwidth to avoid compression anomalies. The present invention provides dynamic flexibility of information speed to offer subscribers the best possible signal quality.

BRIEF DESCRIPTION OF THE FIGURES.

The instructions of the present invention can be easily understood by the following detailed description, in conjunction with the accompanying illustrations, in which:

Figure 1 illustrates a high level block diagram of an interactive information distribution system in accordance with the present invention;

Figure 2 illustrates a block diagram of a video session manager;

Figure 3 illustrates a flowchart of a session security routine;

patentbrons533-002 / diva /

<img file="AR010689A1_D0005.tif" />

/ 7 and 'Ì · {·

Figure 4 illustrates a block diagram of the video session manager; Y

Figure 5 illustrates a detailed block diagram of a fixed upper terminal.

To facilitate understanding, whenever possible, equal reference numbers were used to designate those identical elements common in the figures.

DETAILED DESCRIPTION.

The invention consists of an efficient interactive information distribution system, which provides information to an individual or a number of subscribers, such as multimedia programming, audio, videos, graphics, and the like. This information is available "on demand". In addition, the system allows subscribers to control the presentation of information in real time, for example, it can start, stop, pause, go back, move forward and derive the requested information stream without substantial latency. The information can be provided to the subscribers through general broadcast, in which all the subscribers receive the same information; pointcast [pointcast] in which each subscriber receives specific information that is only addressed to that subscriber; or limited broadcast [narrowcast], in which a subset of the total subscribers receives certain information.

The system as described is summarized below. Subsequently, each component subsystem of the system of the invention is discussed individually and in detail.

A. System Summary.

Figure 1 is a high level block diagram of the interactive information distribution system 100 of the present invention. The system contains an information server 102, at least one 7 patentbrons533-002 / diva / video session manager 106, a network administrator 114, office subsystems 116, a cable transport network 110, and an amount of subscriber equipment 124. The subscriber equipment 124 includes a fixed upper terminal 118, an input device (for example, a remote control 120) and a display device 122.

The information server 102 provides a quantity of packetized data streams, via path 104, and a synchronization clock signal, via path 103, to one or more video session administrators (one of which is illustrated only). Alternatively, the plurality of data streams is transmitted by multiplex on an optical fiber (a trunk) and each video session manager is connected to the trunk by a "downline". The number of video session administrators is proportional to the number of subscribers the system is attending, for example, each video session manager can generally serve up to 2,000 subscribers. The server 102 provides information (data streams) in response to specific requests for information from the video session manager that are communicated to the server through the communications network. The video session manager performs various control and command functions of the system, as well as communicating data streams to the cable network. In itself, the system uses three directional communication channels to carry out communications and control operations. The video session manager can direct the streams so that they are propagated to the subscribers in the modes of general broadcast, limited broadcast and punctual broadcast.

Specifically, the video session manager modulates each of the baseband data streams on a carrier signal and converts and raises the signal to a transmission frequency that meets the frequency spectrum of conventional cable television (CATV) . As an 8 patebrons533-002 / diva /

<img file="AR010689A1_D0006.tif" />

For example, the downstream data modulation is, for example, 64-year quadrature amplitude modulation (QAM) and the transmission frequency is in the range of 50 to 750 MHz. Other types of modulation and bands can be used. of frequency. This information is coupled to the cable network via path 108 and is transported through the cable network on what we will call the information channel.

The video session manager 106 also transmits control information through a downstream control channel (path 107) contained within the cable transport network 110 to the subscriber's equipment 124. This control and command information is transmitted. on a carrier in the range of 50 to 750 MHz using a bandwidth of 1 MHz, for example, the command information is transmitted by multiplex frequency with the information channel and through the network 110. Also, the subscriber equipment 124 communicates via a reverse (or later) channel with the video session manager 106 through the cable transport network 110 and the path of the reverse channel 109. There are typically 16 of those reverse channels Supported by each video session manager. Each reverse channel carries, for example, a serial BPSK modulated on a carrier in the range of 5-42 MHz, in which the capacity of the channel is approximately 64 kbps. Other frequency ranges, modulation types or channel capabilities can be used.

In addition to the information that can be manipulated interactively, the system allows the communication of television signals by conventional cable (analog signals) to the subscriber's equipment. Specifically, a conventional cable signal source 126 (for example a conventional cable header) is coupled to an input of a signal adder 128. The other input of adder 128 is coupled to path 108 from the video session manager. 106. In itself, conventional patebrons533-002 / diva / // cable signals are propagated to the subscriber's equipment to complement the interactive information provided by the information provider.

The cable transport network is, typically, but not exclusively, a conventional bi-directional hybrid fiber coaxial cable network. Depending on the size of the fiber node, the invention requires available between two and five conventional cable channels (for example, 6 MHz channels of bandwidth) to effectively provide services to about 2,000 subscribers. In addition to the downstream information channels, the network must also support the downstream control channel and the upstream rear channel.

The subscriber equipment 124 is coupled to the cable transport network 110 by the path 105 (for example, coaxial cable) and contains a fixed upper terminal 118, an input device 120, and a display device 122. The upper terminals Fixed 118 receive and demodulate the downstream signals including those propagated through both the control channel and the information channel. The fixed upper terminals also optionally demodulate standard cable television signals received from the network. Thus, a single fixed upper terminal can be used to receive all cable services provided by the network. The fixed upper terminals also allow interactive control of the presentation of information. The presentation is controlled via the input device 120, for example, an infrared (IR), radio-frequency (RF), or other remote control unit. The information, for example, audio, video, photographs, graphics, multimedia programs and the like, is displayed on a display device 122, such as a television, video monitor, stereo system and the like.

The network administrator 114 manages the system elements, provides security measures, and ensures the synchronization of all components 10 patebrons533-002 / diva / of the system. The network administrator communicates all system components via a busbar architecture [bus] of communications. This busbar can be implemented using a conventional ETHERNET architecture, standard communications or standard network. The network administrator 114 also communicates with the office subsystems 116 that maintain the subscriber's account management software. This software performs billing and accounting functions, correlating the subscriber's identification numbers with the requested information resources and the price of that source of information. Such office systems do not form part of the present invention in any way; therefore, this component of the system will not be discussed in more detail, and is only mentioned for the purpose of completing the information.

In operation, each unique upper terminal is assigned a unique identification code and each subscriber has a defined personal identification number (PIN). PINs can be assigned by family or by each member of a family, for example, children can have PINs different from those of parents. The assignment and administration of PINs is presented in the

Joint US Patent Application 08 / 738,343, filed on October 25, 1996, and incorporated herein by reference.

For the subscriber, the default system signal exists from the fixed upper terminal for processing by an output device, such as a television or other equipment, depending on the nature of the output signal.

On the subscriber's television, a channel may appear as a default within the plurality of cable channels available to the user. The default signal can be presented as an “announcer” channel that invites a viewer to subscribe or access the service or, at least, to take a look through a number of available information offers. The 11 palçntebron $ 533-002 / diva /

». - -.

/fa'

<img file="AR010689A1_D0007.tif" />

The default system signal, if it is in the form of an announcer channel or another cable channel, is continuously broadcast to all subscribers and potential subscribers. The announcing channel can be analog, digital, or both, as determined by the fixed upper terminal.

If interested, the viewer chooses to enter the system by manipulating the buttons (or joystick) of the remote control 120. During the selection process, the viewer (now a potential subscriber) is presented with a browser on the screen (an interface graphic generally known as a browser) that helps the viewer find information, selection prices, search aids and the like. The commands used to navigate through the different menus are transmitted from the fixed top terminal to the video session manager, via the back channel. The video session manager responds to customer requests via the control channels and downstream information. When the subscriber runs the browser, the video session manager opens a session for that particular subscriber.

Once a program has been chosen, for example, a movie, the video session manager 106 associates the chosen program with the session opened for that particular subscriber. The subscriber's PIN is requested and controlled against a database of PINs managed by the network administrator

114 Also, the identity of the fixed upper terminal is checked against a database of terminal identifications to verify that the order is being made from an authorized terminal. Each available program has a set of unique identification numbers or PIDs.

Thus, when a program is requested, the video session manager 106 sends the PID to the server 102 through path 103. In itself, the server retrieves the program from memory and provides the requested information to the session manager. video as a data stream 12 patebrons533-002 / diva /

<img file="AR010689A1_D0008.tif" />

packaged Data stream packets are directed to the appropriate TID and carry the requested program PID. The video session manager processes the data streams for transmission to the cable network and the fixed upper terminal retrieves all packets addressed to its TID. The upper terminal sets, decodes and decompresses the information for presentation to the subscriber.

At any time during the presentation of the requested information, the subscriber may request that special functions be performed. For example, the subscriber can start another session, temporarily suspending the previous session. Likewise, the client can stop, pause, rewind, or quickly advance the information. The subscriber can leave the system and return later to watch the program from the point where he interrupted. Each of these functions is achieved by manipulating the remote control. The fixed upper terminal sends the control information via the subsequent channel to the video session manager. The video session manager informs the server of the control command for its implementation and also informs that instruction to the network administrator, so that billing can be conveniently modified. In this way, the subscriber is offered a fully functional information-on-demand system in real time.

An important feature of the invention that allows the flexibility of said system is point-to-point synchronization. To facilitate end-to-end synchronization, the server uses a high-precision clock signal (level 1) as a reference signal for all server timing. In itself, all data streams are synchronized with the reference signal (synchronization clock serial). Also, the reference serial is supplied (path 103) along with the data streams to the video session manager. The video session manager uses a unique oscillatory source hooked per phase to the reference signal to modulate all data streams so that the streams remain synchronized. The currents carry timing data via synchronized transitions to the fixed upper terminals, so that each fixed upper terminal is synchronized to the current being received at that time. Since all currents are synchronized with each other, the fixed upper terminals can jump without gaps from one current to another without incurring timing errors, that is, re-synchronization is not necessary.

Each of the system component subsystem blocks is discussed in detail below.

B. Server 102.

The server 102 is typically a parallel computer-processor system capable of accepting information requests from the video session manager 106, retrieving that information from memory, and generating a plurality of program streams containing the information. One of these servers is the SARNOFF SERVER computer system, manufactured by Sarnoff Reai Time Corporation, of Princeton, New Jersey. SARNOFF SERVER is a registered trademark of Sarnoff Reai Time Corporation. The SARNOFF SERVER computer system has an input bandwidth of 5.4 Gbps and, at its maximum capacity, can handle up to 10.8 Gbps of program material. Program information may be stored within the disk drive controller of the computer system, in an offline storage system, such as a library of optical discs, and / or be available in a real-time program feeder (digitai or analog).

patentbrons533-002 / diva /

/.7/- ... _z\ v ^;Z

Me

Bc-Ai r

r^!F

... ._z

Server 102 provides a plurality of dat-³ ^ nmltip streams scanned by time division, for example, thirty-two, which contain the information requested by the video session administrators to handle the requests of a multitude of subscribers. These signals can comply with the MPEG-2 standard for the so-called "elementary currents"; "System currents"; and "transport streams." These data streams are generally formatted in transport packets that comply with the MPEG-2 transport protocol or a similar transport protocol. The multiplexing and packetization process can be performed within the video session manager; however, the packetization can be handled more efficiently by an outgoing server subsystem or the data can be pre-packaged and stored in the data storage devices associated with the server. In itself, the server provides requested information in a plurality of transport streams that have the information requested by many subscribers packetized and multiplexed into thirty-two independent streams. Each packet carries a TID of a requesting fixed top terminal and is presented to the video session manager at a particular output port, for example, one of the 32 ports. Additionally, the server provides the high precision clock signal (reference signal) on path 103.

Alternatively, the plurality of data streams is multiplexed to an optical cable and a "multi-slot" technique is used to distribute the streams to the different video session managers. Specifically, a plurality of "down lines" connects the video session managers to the optical cable (a trunk) and the streams are directed to the appropriate video session manager.

patentbrons533-0O2 / diva / /., · / · '

V ȍ

<img file="AR010689A1_D0009.tif" />

<img file="AR010689A1_D0010.tif" />

To facilitate timing synchronization, the packages used to propagate information to the fixed upper terminals have a fixed length (ie, a fixed duration). In essence, the packetization process converts multiple access currents by time division (TDMA) to multiple access currents by division into packets (PDMA). Consequently, the duration of the package defines a fundamental unit of time for the system. In itself, the start or end of each packet provides an adequate timing signal that can be used by the fixed upper terminals for synchronization.

C. The Video Session Manager 106

Figure 2 illustrates a block diagram of the video session manager 106. As already mentioned, the system generally uses multiple video session managers. Each administrator provides information to up to 16 conventional cable transport network nodes ("neighborhood nodes") that have up to 2,000 subscribers each. Each video session manager distributes up to 320 streams of different programs to the nodes.

The video session manager 106 contains the stream distributor 200, a digital video modulator module 202 (DVM, also known as a DVM Rack) containing a plurality of DVMs 203, an instruction and control module 216, and a module of output (cross coaxial connection 214). The video session manager 106 also includes a backup DVM 204 module, which contains a DVM 205 that can be replaced by any of the DVMs 203 that use a 1 for a backup scheme n. Stream distributor 200 routes the plurality of data streams from the server to all DVMs 203.

Each DVM has two output ports that serve one or two neighborhoods.

Also, each of the output ports can carry one or two channels 16 patebrons533-002 / diva /

<img file="AR010689A1_D0011.tif" />

of information. In this way, the DVM module generates four digitally modulated channels whose frequency agility is independent. The output combiner 207 combines the 4 channels into two pairs of two channels.

As mentioned with respect to the description of the server, the circuit boards of the video session manager 106 may contain a packetizer 206 (shown as a spectrum), such that the server provides multiple access system streams by time division and The DVM packages the information in transport packages, complying with the MPEG-2 nor with some other transport protocol, that is, a stream of multiple access data by division into packages. However, to efficiently process information streams, the server generally provides packetized information before providing the streams of data to stream distributor 200. In itself, the packetizer is not necessarily a portion of the DVMs.

In addition, each DVM contains four modulators 208 that modulate each transport stream to a 64-year QAM signal with block interleaving and anticipated error correction. The frequency booster converter then converts and raises the QAM signal to a certain frequency for transport over the cable network, for example, a frequency in the range of 200 to 750 MHz is commonly used. The frequency selection and modulation process are controlled by a controller 212 that operates under the control of the DVM 222 interface.

Each of the DVMs (there are usually eight DVMs) modulates four data streams. The output module 214, for example, a cross-coaxial connection unit, combines the downstream information channel with the upstream instruction information produced by the controller module 216.

patentbrons533-0O2 / diva /

The controller module 216 contains an interface ^ / E&gt; YM-222 / a session control manager (SCM) 220, and therefore a control channel modem 218. The control interface 224 has a conventional network architecture of area locai for communication between the server and the video session manager. The DVM 222 interface has a conventional RS-482 bus bus architecture that interconnects the 212 controllers for each DVM 203 and the session control manager 220. The RS-482 architecture can be replaced by other multi bus bar architectures. -point, taies like ETHERNET.

The control channel modems terminate the control signals upstream and downstream from / to the fixed upper terminals. A single control and command modem can be used for each network node or for a plurality of nodes, depending on the communications traffic. Within each modem, the upstream demodulator is by way of example a binary phase change teda demodulator (BPSK) 226, while the downstream demodulator is, for example, a quadrature phase change teda modulator ( QPSK) 228. Of course, other modulation formats can be used. Typically there are four demodulators upstream 230, for each downstream modulator

228.

The control session manager 220 is implemented using a commercially available microprocessor and operating system. The microprocessor must be fast enough to handle the control functions in real time.

In particular, the control session manager (SCM) 220 forms an interface to the fixed upper terminals, as well as to the DVM modules 202 and 204 and to the control interface (for example, the bus bar [bus] VME

112 in Figure 1) 224. The responsibilities of the SCM include setting 18 patebrons533-O02 / diva /

<img file="AR010689A1_D0012.tif" />

at the entrance of the fixed upper terminal and the expiration of time, authentication, configuration, and termination of the control protocol; alarm management and frequency assignment; session security; service selection and control; event notification and usage measurement; and the subscriber's access to information about an account. The instructions and orders from fixed upper terminals are processed by the SCM and the appropriate orders are made to the file server to perform certain information navigation and movie-on-demand functions.

Typically, there are nine DVMs (eight active modulators 202 and one reserve 204) attached to and controlled by a single SCM. Physically, the DVM and SCM modules are housed in a single rack [rack]. Each DVM module is assigned to the SCM by connecting its interface to an RS-482 controller of the SCM (DVM 222 interface) and entering the address of the RSM-482 DVM into an RS-482 controller configuration database.

The configuration of the DVM module contains sixteen fixed upper terminal neighborhoods, each DVM serving two neighborhoods using each of the DVM's output ports. However, if one neighborhood is using the movie-on-demand service more than another, the DVMs are removed from the attention of a neighborhood and added to the attention of the neighborhood with the highest demand, that is, the DVMs are agilely independent. The SCM simply keeps track of a number of “pools” of DVMs, the DVMs being output from each pool combined and broadcast. As long as bandwidth is available on the upstream and downstream channels, DVMs can move dynamically from one pool to another.

The pools, in addition, are configured to allow only a subset of the DVMs to be active simultaneously. The remaining 19 patebrons533-002 / diva /

<img file="AR010689A1_D0013.tif" />

IJ I

DVMs are available as reserve and are automatically assigned when one of the active DVMs fails or is removed. Additionally, to increase subscriber service capacity, neighborhoods can operate without a DVM backup module.

As an example of the session security provided by the SCM, the SCM is able to periodically change the output frequency of the DVMs to make it more difficult for a non-subscriber to get the service for free. Figure 3 illustrates a flow chart of this important feature of the invention. Security session routine 300 begins at step 302 and goes to step 304. In step 304 the SCM selects an active DVM; in step 306 it combines its output in a backup DVM (but modulating at a different frequency); in step 308, program the fixed top terminal to decode from the location of the new DVM; and then, in step 310, release the true DVM. The session security routine ends in step 312. This security measure requires the availability of a single free DVM frequency.

Returning to Figure 2, a bus bar containing 32 transport streams (path 104) and a high precision clock signal (sync) (path 102) is provided from the file server. The synchronization clock forms a daisy chain through the DVMs within a support. Each DVM is configured to extract one of the 32 transport currents for modulation. All data streams are synchronized with the synchronization clock signal. In addition, all DVMs operate from a common frequency source that is connected by phase to the synchronization clock. In itself, all DVM output currents are synchronized. DVM redundancy is done by configuring the backup DVMs to extract the transport current that was carried by an active parallel DVM and to modulate the 20 patcntebrons533-O02 / diva /

<img file="AR010689A1_D0014.tif" />

same frequency

An SCM communicates with its fixed upper terminals through a plurality of control channel modems (CCM) 218. A neighborhood is generally served by one or more CCMs; however, broadly speaking, a given CCM can serve multiple neighborhoods and a plurality of neighborhoods can be served by a given CCM. The fixed upper terminals that are connected to a given CCM must fight for the upstream channel that is available to propagate control signals from the fixed upper terminals to the CCM and SCM.

The CCM modulates blocks of data transmitted to the control channel downstream and demodulates the blocks of data received from the rear channel upstream. The upstream bandwidth is approximately 64 kilobytes per second, while the downstream bandwidth is approximately 1 megabit per second. The CCM also provides a solid error detection and correction process.

The CCM can be configured by its frequency for both the upstream channel and the downstream channel. Once the system is installed, the cable transport network is analyzed to locate the least noisy portion of the available spectrum. The fixed upper terminals are then set to transmit and receive at the chosen frequencies that have the lowest noise. The CCMs are configured to use the frequencies programmatically of the SCM. The SCM is interfaceally connected to the CCMs through a printed circuit board connector of the SCM rack using a shared mail box approach within the VME busbar architecture. A simple reliable link protocol is applied in both directions resulting in the guaranteed delivery of data packets.

patentbrons533-002 / diva /

<img file="AR010689A1_D0015.tif" />

Since for each path there is only one CCM that transmits in the downstream direction, and that the upstream and downstream paths are independent, a downstream signal collision cannot occur. Therefore, the CCM can transmit whenever it has information to send. Similarly, each fixed top terminal simply transmits every time it has information to send. No collision or carrier sense detection is necessary. When the CCM receives a message, it transmits an acknowledgment to the fixed upper terminal that sent it. If the fixed upper terminal does not receive an acknowledgment within the time it takes to transmit the packet, process it and acknowledge receipt, the fixed upper terminal assumes that the message was interrupted and was not received. In that case, the fixed upper terminal makes a random waiting period and then relays the message. A sequence number is used per fixed upper terminal to prevent repeated messages from being passed to higher levels of the SCM software. Since there is no collision detection, there is no relationship between the minimum packet size and the maximum distance between two nodes in the network. A low frequency support survey, in the order of one every five minutes, is required by the fixed upper terminals that have been deactivated so that the currents assigned to those DVMs can be released for use by other subscribers. The polling frequency determines the maximum time between the moment when the subscriber cuts the power and the moment when the SCM reallocates the current and interrupts the billing function to the subscriber.

The traffic of instructions from the fixed upper terminals is generally by spikes. Subscribers enter instructional information to the fixed upper terminal, interact for one or two minutes with the terminal, and then watch a movie for a prolonged period of time 22 patebrons533-002 / diva / time. The fixed upper terminal is programmed to wait for an acknowledgment long enough for the message to propagate upstream, to be processed, and for the acknowledgment to propagate downstream. The fixed upper terminal must wait approximately 80 micro-seconds before waiting and relaying the message after not receiving an acknowledgment. As an example, the [backoff] waiting period begins as small enough to resolve a transmission collision between messages from two fixed upper terminals and increases exponentially to resolve a collision between sixty-four or more fixed upper terminals. If the transmissions of two fixed upper terminals collide, ideally, one must retransmit immediately and the other must retransmit after at least the worst transmission delay period, approximately 3 milliseconds. The wait time [backoff] is a multiple of the worst case of delay chosen as a random number less than the maximum transmission delay, which doubles after each successive collision.

The downstream instruction channel has no collisions, but it is subject to packet loss due to network noise. Therefore, the fixed top terminal answers with an acknowledgment every time it receives a message from the CCM. If this acknowledgment is not received within the time it takes to transmit the message, receive it, process it and queue the acknowledgment and transmit it, the message is sent again. Note that, since there can be no collisions, a waiting period is not necessary.

Figure 4 illustrates a block diagram of the hardware [hardware] of the

SCM 220. This equipment has a central processing unit [CPU] 400, a random access memory [RAM] 402, a read-only memory [ROM] 404, an RS-482 406 interface, a connector board interface of VME 422 printed circuits, and 408 CPU support circuits, taies 23 patebrons533-002 / diva /

74) like a clock, cache memory, power source, etc. ìia ^ RA-IS / Ì ^ 402 contains (an) application program (s) 410, a configuration database 412, a subscriber database 414, a "browser" menu tree 416, session structures 418, and entities of the operating system 420. All programming for the SCM is conducted using object-oriented programs.

The subscriber database 414 provides information on each subscriber. The database may or may not be downloaded as part of the configuration database 412. The subscriber database includes information regarding each fixed upper terminal, including one or more personal identification numbers (PINs), a number of terminal identification (TID), the current state of the terminal, etc. Subscribers can modify their PINs using their fixed top terminals; therefore, subscriber objects such as PINs are likely to be rewritten in the database. The presentation of an example of a PIN management method and device appears in US Patent Application for Joint Assignment 08 / 738,343, filed on October 25, 1996 and incorporated herein by reference.

The session database 418 is built by the SCM during runtime. The SCM manages sessions dynamically as they are created and deleted. This database contains a different database structure for different types of sessions. For example, an ad session that starts when a viewer tunes to an announcer channel is associated with a database that contains the identification of the fixed upper terminal that has been tuned to the announcer channel and the status of the terminal. The status of the terminal describes the type of programming the terminal is processing, that is, analog mode, display of announcements (general broadcast mode), 24 patents viewbrons533-002 Z diva / \ '·' / -&gt; \ · - / browser, program viewing and the like. Also, a- / sésióri of movies produces a session database that contains the TID of the terminal that sees the movie, the state of the terminal, a PID, a timer expiration value that indicates when the movie is expected to end , a timer use value that indicates the duration of the session, the identification of the subscriber (eg PIN) and the like. Also, for a browser session, that is to say a session in which the subscriber is browsing the available information selections, the session database 418 contains a TID and its status as well as historical information related to the navigation function.

The configuration database 412 describes how the equipment [hardware] is configured, for example, that DVMs are active or on hold, available frequencies, terminal configuration information, DVM information, etc. The database is either downloaded or recovered from non-volatile locai storage.

The menu tree in browser 416 is downloaded from the file server when the SCM does its loading routine. The tree is composed of a set of nodes of variable length and an index that provides the deviation of a node given its identification number. The tree describes the particular pattern of browser movements available to a subscriber and what programming is available to a particular subscriber as defined by the PIN of that subscriber. For example, a subscriber who has entered a PIN that gives “normal” vision authorization will be able to use “browser buttons” that facilitate navigation and the progress view of all non-adult material. In itself, the menu tree structure used by this subscriber will not include referrals to adult material. By contrast, a subscriber who enters a PIN that authorizes access to the so-called “night programming” uses a structure of 25 patents 503-002 / diva /

Fl · â tree different from the one used for normal vision. The tree structure of the evening program includes access to buttons that allow viewing of adult material. In each case, each tree is activated on the basis of subscriber per subscriber and defines the way in which the browser is executed for each subscriber. A detailed description of the navigator appears in the US provisional joint application patent application, series number 60 / 034,490 filed on January 13, 1997 and incorporated herein by reference.

The ROM 404 contains software that is capable of performing an "energy self-test" and performing a routine of loading a software image from a network. The ROM is about 256 kilobytes. Non-volatile memory is programmed during manufacturing to store a network address, serial number, date of manufacture, and component review levels. There is no other requirement to save any other configuration information in a system load routine.

The RS-482 interface has at least six ports, one port connected to the bus bar of the RS-482, one for the SCM and four for the DVM interface modules. The central processing unit [CPU] 400 of the SCM is a 68K family microprocessor marketed by Motorola. Preferably, the CPU 400 microprocessor is the 68040 enhanced 32-bit microprocessor that has 8 kilobytes of cache, MMU and FPU, and runs at a clock speed of approximately 25 to 33 MHz. Such a processor that includes a VME busbar interface, on-board RAM, a SCSI interface, non-volatile memory, communications ports, various clock and timers, an RS-482 transceiver interface, and ROM is available at a single CPU circuit card like Motorola MVME167 model number. The card is installed in a standard NEBS chassis. Alternatively, 26 patebrons533-OO2 / diva /

<img file="AR010689A1_D0016.tif" />

MVME162 model circuit board, also marketed by Motorola. Either of these two cards are plugged into a 20-slot VME printed circuit connector board, marketed by Motorola, as part number MCI 120.

There are a number of 420 operating systems that can be used with this equipment, including the pSOS + manufactured by Integrated Systems, Inc., the Vx Works manufactured by Wind River Systems, the VRTX manufactured by Microtec Research, Inc., the QNX manufactured by QNX Software Systems, Ltd., and the OS / 9 manufactured by Microware.

As already mentioned, the SCM also maintains the synchronization of the end-to-end system, for example from the server to the fixed upper terminal. The server has great accuracy, clock level 1, which is provided to the stream distributor 200 in Figure 2. Each of the clocks is from the video session manager 106 are derived from this clock signal. DVM clocks are used to retrieve information from the stream distributor 200 and to synchronize the distributor information in packages for modulation. Thus, all the information is synchronized according to the synchronization clock. The output bit rate is times the MPEG-2 current rate of 3.37125 Mbps. This is directly proportional to the 29.97 frames per second of conventional video signals. That is, the system clock is incorporated into the bitstream. The same clock signal is used as a base to modulate all information flows. In itself, the same clock signal is sent to each fixed upper terminal. The clock is removed by the fixed upper terminal (for example, frequency and phase hitch) to provide synchronization of the end-to-end system. Due to this end-to-end synchronization, conventional MPEG-2 transport circuits are not necessary to remove the fluctuation by separating the information. By 27 patcntebrons533-002 / diva /

Ph elio, the fixed upper terminal is less complicated and more economical. Likewise, a fully synchronized system allows you to jump from one current to another without re-synchronization.

The system offers fixed multiplexing regimes, that is, 8 server-side channels of 3.37125 Mbps, or less than 8 over-system channels, for example, multiples of 3.37125 Mbps. For special transmissions that require a greater width of band, a program can be sent using a plurality of channels. For example, the bandwidth necessary to properly present a basketball or football program is probably greater than the bandwidth required to properly present a black and white film.

The system is able to dynamically allocate the resources of the information channel to the subscribers. Allocation decisions are based on subscriber program requests and the use of resources by subscribers. For example, programs can be characterized according to their content during, for example, a storage or pre-transmission operation. This characterization provides an indication of the level of resources of the information channel (ie bandwidth) necessary, desirable or optimal. The subscriber requesting a program that requires a high level of resources from the information channel (for example, a basketball game) will be assigned an additional sub-regime channel or a super-regime channel (if available). A subscriber requesting a program that requires a low level of information channel resources (for example, a black and white film) will be assigned less or only one of the sub-regime channels. If a subscriber who has been assigned one or more sub-regime channels or a super-regime channel terminates a session, the bandwidth released by the outgoing subscriber can be re-allocated among the remaining active subscribers. 28 patentbrons533-002 / diva /

V'-^{â 0}

Ideally, all subscribers receive programs with an optimal level of information channel resources. The system monitors several load parameters and makes resource allocation decisions in accordance with that ideal. When a session ends, the video session manager terminates the session and clears that particular session database. If pause is selected, after a period (of, for example, 2 minutes) the session is terminated.

D. The Cable Transport Network 110

The cable transport network 110 of Figure 1 is a conventional hybrid fiber coaxial cable (CATV) television system, which has a direct information channel (upstream in-band information channel) operating at between 50 and 750 MHz. This channel carries broadband information to the subscriber's fixed top terminal. The network also carries the direct instruction control channel (upstream out-of-band channel) that operates between 50 and 750 MHz and a reverse or back channel (downstream out-of-band channel) that operates between 5 and 42 MHz. The cable transport network also contains line amplifiers and conventional receiver / bridge amplifiers to ensure that each of the fixed top terminals connected to the network receives a high quality signal. In itself, the network is capable of supporting three unidirectional channels.

Although the cable transport network is described, for the purposes of the example, as a hybrid fiber coaxial cable network, other forms of network, such as all-fiber, all coaxial, or any other communications network may be used. broadband that supports three paths of unidirectional communications.

E. Fixed Top Terminal 118.

patentbrons533-O02 / diva / r. . · Fa - 'fa' fa \ ·&gt; / 'FOLiü

The fixed upper terminal 118, of Figure 1, receives the modulated QAM signal from the cable transport network and demodulates the signal. The fixed upper terminal demodulates and depackets the in-band QAM signal and demodulates the upstream control signals and modulates the downstream control signals. Although the term "fixed upper terminal" is used herein as the transceiver portion of the subscriber's equipment that performs its functions separately from the other portions of the subscriber's equipment, it should be noted that the functionality of the fixed upper terminal can be integrated into the subscriber equipment to form a single consumer electronic product, for example a television that has a transceiver of the present invention incorporated.

In particular, Figure 5 presents a block diagram of the fixed upper terminal 118 containing a transceiver 500, a central processing unit (CPU) 512, and a display controller 522. The CPU 512 is supported by RAM 520, ROM 518 and several 516 support circuits, such as clockwork, power source, infrared receiver, etc. The transceiver 500 contains a diplexer 502, a rear channel modulator

508, an information channel demodulator 504, an instruction channel demodulator 510, an information decoder 506, a conventional television signal signal demodulator 524, and a multiplexer

526 The diplexer 502 couples the three channels transported by a single cable within the network, to the modulator and to the demodulators. Each demodulator

504 and 510 tunes and converts and reduces the frequency of the cable network signals in a conventional manner. The information channel demodulator 504 is a standard QAM demodulator, such as the model

BCM3115 manufactured by Broadcom. There are other such demodulators well known in the industry. However, this particular QAM demodulator also contains a built-in “out-of-band” demodulator 30 patebrons533-002 / diva /

<img file="AR010689A1_D0017.tif" />

QPSK to handle information from the command channel, transported by the direct instruction channel. In itself, a single integrated circuit can process both the information requested by the subscriber (audio and video) as well as the control data.

The decoder 506 processes the data packets that carry information requested by the subscriber produced by the QAM demodulator to signals usable for the end-user display device, for example, television, VCR, and the like. The information to be displayed is processed conventionally by a 522 display controller to produce composite video as well as a conventional television signal.

The conventional cable television signal demodulator 524 contains a tuner and an analogue demodulator (NTSC). A multiplexer 526 couples the decoded or analog demodulated video signal to the display controller 522.

The demodulated QPSK signal provides command and control information to the CPU 512 to generate certain graphics and control interface regions on a television screen. The CPU can be, for example, a Model 68302 processor, manufactured by Motorola. This processor, operating in combination with decoder 506, produces "buttons" or regions that can be displayed on the screen with which the subscriber interacts using an infrared remote control 120.

Specifically, a joystick [joystick] on the remote control highlights eligible regions or icons on the television screen. When a certain icon is highlighted, the subscriber presses the “choose” button on the remote control that sends an infrared signal to an infrared receiver (a support circuit 516). This receiver sends the instruction to the CPU for interpretation. If the instruction is a request for implementation of a 31 patenîebrons533-002 / diva /

G,.

local function, for example volume control, the CPU executes the function locally. However, all non-local functions that involve a request for information or the manipulation of the presentation of the information are communicated to the service provider. In itself, the processor formats the instruction and sends it to the rear channel modulator for transmission to the video session manager.

The available non-local session control instructions are infinitely variable including, without limitation, choosing, running, stopping, rewinding, moving forward, pausing information, etc. The control instructions are sent via a BPSK 508 modulator and an internal transmitter through the rear channel, to the CCM. The CCM demodulates and couples the instruction to the SCM that implements it. The operation of the navigator that facilitates finding, communicating, and controlling information is presented in the US provisional application for common assignment no. 60 / 034,490 filed on January 13, 1997.

Although several embodiments that incorporate the teachings of the present invention have been described and illustrated in detail herein, those skilled in the art can easily design many other different embodiments that also incorporate these teachings.