Set-top electronics and network interface unit arrangement

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SET-TOP ELECTRONICS AND NETWORK INTERFACE UNITARRANGEMENT SAMSUNG ELECTRONICS CO., LTD.C:31279 124603/2 WO 97/19565 PCT/US96/18797

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SET-TOP ELECTRONICS AND NETWORKINTERFACE UNIT ARRANGEMENT 10 Field of the Invention

The present invention relates to multimedia digital networks, and more particularly, to set-top boxes forinterfacing with external network and entertainmentservice providers and converting the received information 15 for use or display by in-home products, such as televisions. /

Background of the Invention

The rapid gains in digital technology and telecommunications have increased the desirability of20 having a network in the home to interconnect a multitude of products in the home with each other and to theoutside world. The range of available outside servicesincludes interactive services, cable video and audio services, satellite networks, telephone company services,25 video on demand, and other types of information services. 2

However, penetration of the personal computer into homesin the United States is approximately 33% and onlygrowing slowly, although governments desire moreextensive penetration to encourage "telecommuting" andreduce road traffic and pollution. Further penetrationof computers in the home will originate from the purchaseof consumer entertainment and informational productscontaining an embedded computer and operating systemhidden by an opaque user interface. Such a product is aconventional set-top box.

Set-top boxes are multi-media computers that augmentthe use of televisions. A conventional set-top box hasan external network interface module that connects theset-top box to the external network and data provider.The network interface module has to perform a number ofsophisticated functions, such as interfacing to aspecific external network, tuning, demodulation, errorcorrecting, video descrambling, recovery of MPEG clock,and encryption and decryption specific to the externalnetwork. Consequently, the network interface module isa relatively expensive component of set-top boxes. Thisexpense would be necessary when even a single televisionis present in the house. However, most homes containmultiple televisions, and providing each with its ownset-top box and associated network interface module is aduplication of expensive components.

Another concern for homeowners is the issue of theservice providers. Limitation to one service providerfor all services introduced into the home through a set-top box, such as by a telephone provider, restricts thechoices of a homeowner and possibly prevents thehomeowner from obtaining services at the lowestcompetitive price. Attempting to overcome this problemwith multiple service providers using a stack of multipleset-top boxes on every television in a home is not aviable solution. 3

Summary of the Invention

There is a need for . a set-topcomputer/audio/video/graphics electronics that with atelevision display forms an entertainment terminal andnetwork interface arrangement in a single home to accessthe data from multiple external networks.

These and other needs are met by the presentinvention which provides an arrangement in which the set-top electronics that support the media output devices,such as televisions, are separate from the networkinterface units that interface to external networks. Theseparation of the network interface unit functions fromthe set-top electronics allows a single network interfaceunit to be used to interface with an external network andprovide programming selectively to a multitude of set-topelectronics and televisions within the home. Thisreduces the need for duplication of the network interfacefunctions at each television or other end product (mediaoutput device) and thereby reduces the costs for thetypical homeowner who will have more than one televisionset in the home. Further, having multiple separatenetwork interface units on the network allows theconsumer to pick and choose among available services, andnot be constrained to a single service provider.Changing a service may be performed simply by exchangingor adding a different network interface unit configuredto interface with the new external network.

The foregoing and other features, aspects andadvantages of the present invention will become moreapparent from the following detailed description of thepresent invention when taken in conjunction with theaccompanying drawings . 4

Brief Description of the Drawings

Figure 1 is a schematic block diagram of a home network constructed in accordance with an exemplaryembodiment of the present invention. 5 Figure 2 is a depiction of an exemplary installation of the home network of the present invention within ahome .

Figure 3 is a logical diagram of the home network ofFigure 1. 10 Figure 4 is a schematic depiction of a network interface unit and a set-top electronics unit constructedin accordance with preferred embodiments of the presentinvention.

Figure 5 is a block diagram of a network interface 15 of the set-top electronics constructed in accordance with an exemplary embodiment of the present invention.

Figure 6 is a block diagram of the network interfaceof the network interface unit constructed in accordancewith an embodiment of the present invention. 20 Figure 7 is a block diagram of a hub and direct circuit crossbar, constructed, in accordance with anembodiment of the present invention, coupled to a networkinterface unit and a set-top electronics unit.

Figure 8 is a logical diagram of an exemplary user 25 interface for the home network of the present invention.

Detailed Description of the Preferred Embodiments

Figure 1 is a schematic depiction of a home multimedia network 10 constructed in accordance with anembodiment of the present invention. This embodiment is 30 exemplary only, however, as the network 10 may be configured in any of a number of different ways withinthe scope of the invention, and include different devicescoupled to the network 10. Additionally, the inventionis not limited to networks located in homes, but is 35 applicable to networks installed in other types of 5 structures, such as offices, apartment buildings, etc.For purposes of illustration, however, the exemplaryembodiment will be described in the context of a homeinstallation.

The network 10 is a digital network that providesconnectivity of different types of equipment to the worldoutside the home. This equipment can be, for example,analog television 12, digital television 14, digital VCR16, digital camcorder 18, personal computers 20, audioequipment 22, printers 24, facsimile machines 26, andtelephones 28, among others. In addition to connectingthis equipment to the outside world, the network 10 alsoconnects the digital video, digital audio, computer andtelephone equipment together internally in the home.This unifies communication and control within the home,making the full power of the external network connectionsor internal data sources available to any terminal on thenetwork 10.

Communication with the outside world is performedthrough a number of separate network interface units(NIU's) 32 and may be combined physically in an entranceunit 30, with each network interface unit 32 permittinga connection between a different external network and thehome network 10. The different external networks maycarry different types of signals. These may be, forexample, broadcast signals (digital or mixedanalog/digital) carried on hybrid fiber coax or cable.Other types of signals are ISDN, broadcast/digitalsatellite service, FTTC, FTTH, ADSL, and others. Atleast the following data types may be carried: compressedvideo, compressed audio, compressed internet WWW graphicsand data, internet e-mail and other data, computer filedata and control message data.

Logically all terminals in the home network 10receive equal access to the network interface units 32and a user would be unaware of the physical sighting of 6 them. The number of network interface units 32 that are required is determined by the number of streams required per home, e.g. the number of different program channels (i.e., video, audio, and other) required simultaneously, not by the number of terminal units in a home.

In certain preferred embodiments, cable or antennatelevision is retained unmodified with distribution byregular in-home coax (plain old television, or POTV)POTS (plain old telephone service) is also carried on thein-home digital network 10.

The digital signals are distributed throughout thehome over an internal network 34. In certain preferredembodiments, the internal network 34 is essentiallyEthernet of type 10base-T or 100base-T twisted pair buta special switch hub is employed to make the networkscalable to any number of terminal units each able toreceive high bit-rate video.

The home network 10 connects those computers, orproducts with embedded computers, that can support thenetworking bandwidth, protocols, routing, buffering andaddressing. Other high bandwidth products that do notsupport this complex functionality must attach to such ahost unit either directly or via a local peripheralnetwork to achieve interoperability. Examples ofcomputers or products with embedded computers located onthe home network 10, functioning as end user devices,include: the network interface units's I/O computersperforming external network to home network conversionand conditioning; computers, such as the set-topelectronics (STE); PC's; workstations; high end printers;and special computers providing gateway/controlfunctions. Other end user devices that can be coupled tothe network 10 include video products: digital compressed(MPEG) and uncompressed video equipment; digital videocamcorder products; digital video tape recording productsand digital tv display products and analog tv display and 7 recording products. Audio products that can be coupledto the network 10 include: digital compressed (MPEG) anduncompressed audio equipment; HIFI stereo; digital audiotape recording products. Other types of products thatcan connect to the network 10 are data products, such asprinters and other peripherals. Still further productsthat can be controlled through the network 10 includehome automation and appliances: central heating/AC,security controller, microwave oven and other kitchenequipment, lighting, sprinkler and other power control.

Certain embodiments of the home network 10 includeone or more local peripheral networks 15 that providelocal connection for future very high bit rate, motion-JPEG or I-frame-only-MPEG video devices, audio devices,printers and such peripherals. These devices needcontinuous local digital connection at a high bandwidth,where the data transfer is continuous from, for example,digital camera to digital VCR. Accommodating suchdevices directly on the internal network 34 would requiregreater network bandwidth over the entire network 34 thannormally needed. Instead, the local peripheral network15 is normally connected by gateway to the internalnetwork 34 for interoperability. However, in certainother embodiments of the invention, the home network 10is provided with hardware and software that accommodatesthe high speed devices so that a local peripheral network15 is not necessary. A home automation network 17 is provided for homeautomation. This home automation network 17 may run onthe power line or other low bit rate network forcontrolling appliances, home security systems, lighting,etc. This spur originates from a control computer 20located within the home.

An exemplary model of the installation of the homenetwork 10 of the present invention within a house 36 isdepicted in Figure 2. The home network 10 is a long 8 range backbone capable of up to 10 0m cable runs, forexample, from a switched hub 38 that forms part of theinternal network 34. In the exemplary installationdepicted in Figure 2, the entrance unit 3 0 with its 5 multiple network interface units 32 are located in a utility area of the house, along with the switched hub38 .

Twisted pair cable is run to each room of the house36 and terminates at a wall socket. Cat-5 twisted pair 10 (for 100 Mbits/s) , for example, may be used when doing an installation, as the majority of the cost is labor. Fortemporary retro-installation, twisted pair cable is smallenough that it may be customer fitted under a carpet • edge. A user in the home will connect a computer product 15 in a room by plugging the Ethernet port of the computer product to the Ethernet wall socket.

In the embodiment of Figure 2, the hub 3 8 isdepicted as a separate device, but in other embodimentsthe hub 38 is integrated into one or more of the network 20 interface units 32. The hub 38 provides the connectivity to all areas of the house and the one or more networkinterface units 32. Upgrading, expanding both theaggregate bandwidth and connectivity of the internalnetwork 34, is accomplished by additional plugging or 25 changing to a larger hub. The hub will be discussed in more detail later.

The present invention, as shown in Figures 1 and 2,separates the functionality of the network interfaceunits 32 from the set-top electronics 40. 30 Conventionally, a set-top box contains a network interface unit whose components are internally connectedby a. bus to the set-top electronics components. Bycontrast, however, the present invention provides aseparation of the network interface units 32 and the set- 35 top electronics 40, with the internal network 34 interposed therebetween. This arrangement permits 9 multiple set-top electronics to be distributed throughoutthe home 3 6 less expensively, since the electronics of anetwork interface unit do not have to be duplicated foreach set-top electronics. Additionally, having separatenetwork interface units 32 coupled to different externalnetworks and to a common internal network 34 frees thehomeowner from being forced to receive all programmingfrom a single source, such as the telephone or cablecompany. The separation also allows the homeowner toadd, drop or change services simply by changing one ofthe network interface units 32, without the need forreplacing all of the set-top electronics 40, throughoutthe home 36.

In certain embodiments, a "master" set-top box isprovided with multiple network interface units. However,this embodiment is logically the same as described above,as the network interface units are connected in thisembodiment to the internal network, and not by a bus tothe set-top electronics.

Figure 3 is a logical view of the home network 10 ofthe present invention. As apparent from the diagram, themulti-port switched hub 38 forms the center of thenetwork connections. In certain embodiments, in whichinter-packet jitter is adequately controlled, atraditional, commercially available packet switched hubis employed. In other preferred embodiments, such asthat depicted in Figure 3, the switched hub 3 8 is acombination of networked ports and ports that are direct(circuit) switched for the duration of a session. Thedirect connected ports (and systems) can be phase lockedvia the network (coded) clock. To provide thisfunctionality, the switched hub 38 therefore comprises arelatively simple and inexpensive hub 42 and a directcircuit crossbar 44. The hub 42, in certain preferredembodiments, may be a commercially available device, suchas Am79C981 manufactured by Advanced Micro Devices, of 10

Sunnyvale, California. Details of the direct circuitcrossbar 44 will be described later with respect toFigure 7. A star topology as defined by Ethernet 10/l00base-T5 is used in conjunction with the switching hub 38. The switching hub 38 provides fan out to most rooms in thehouse 36. The maximum system bandwidth is a multiple ofthe wire bit rate ((bit rate x number of ports)/2), forexample, 20 ports and 100 Mbits/s bit rate = l Gb/s 10 aggregate maximum bandwidth.

The switched hub 38 enables special treatment forthe heavily asymmetric traffic, e.g., compressed digitalvideo and internet data by directly routing these casesfrom transmitter to receiver. This traffic is thus 15 separated from the internal network 34 and allows an overall aggregate bandwidth to be limited only by theexpandability of the hub 38, although it will remainlimited by the lOMbits/s per branch. Use of 100base-Ttechnology instead of 10base-T technology will uprate the 20 network if required.

The switching hub's direct synchronous (Manchester or block encoded) connections are used primarily for thetransmission of MPEG video where a continuous, high bitrate, long duration connection is required. High bit 25 rate video in compressed form can be as high as 8

Mbits/sec and is needed for live video and high actionmovies and sports. Low bit-rate video is 1.5 Mbits/sec.According to the present invention, MPEG digital video isretained throughout the network 10. Conversion to real 30 video takes place only at the display device (e.g., television 12) or the set-top electronics 40.

Two separate direct circuits are depicted asexamples in Figure 3. For example, the network interfaceunit 32 that is coupled to an ISDN network is directly 35 connected through the direct circuit crossbar 44 to the personal computer 20 of the local peripheral network 15. 11

Another, separate direct circuit is provided by thedirect circuit crossbar 44 between a different networkinterface unit 32 (coupled to hybrid fiber coax, forexample) and the set-top electronics 40 coupled to thetelevision 12. Those devices that are not directlyconnected through the direct circuit crossbar 44 remainattached to the hub 42 and are thus networked.

With respect to the switching hub architecture,where a direct point-to-point path is configured, alldata traversing this path is provided directly to the endpoint terminal of the path, even data intended for one ormore other terminals. Thus, in certain preferredembodiments, a rule is followed that data multiplexedwith the high rate data (typically messaging) must beissued to networked cerminals by the end point of thedirect path returning such packets to the hub 38. Forexample, messages sent over the ISDN network that are notintended for a device on the local peripheral network 15will be returned by the local peripheral network host 20to the hub 3 8 for distribution. This rule saves theexpense and complication of having a packet router typeswitched hub, with the demultiplexing distributed at theend point(s) rather than centrally, and works well forasymmetric data flow and local destination, i.e., notsubject to layers of switches.

An advantage of directly switched paths is thatpotential delays in obtaining access to the network 34(and possibly upsetting the delicate clock referencetiming carried in the MPEG stream) are avoidedaltogether.

The hub 38, in certain preferred embodiments, isrequired to be "full-duplex aware" meaning that adirectly routed path connects only a transmitter terminal"up" path only to a receive terminal "down" path. Bycontrast, the path down to the transmitter and path up tothe receiver are not affected by the direct circuit and 12 would normally be attached to the network, i.e., attachedto all the remaining terminal paths connected together.

Specific routing occurs in response to user servicerequests. Messages are picked up hy the huh control and 5 any direct routing changes implemented. Devices not switched from the network connect and no routing isrequired.

The MPEG clock recovery is performed at the networkinterface units 32, as described later. With the MPEG 10 clock recovery at the network interface units 32, and the establishment of a direct circuit to the home networkdestination, jitter in the signal received at thedestination (such as the television 12) is substantiallyeliminated. Direct circuit capability works well for the 15 heavily asymmetric point to point traffic expected in the entertainment (video) home scenario.

For analog only services, e.g., transitional cableTV,' this is not considered part of the digital network.For mixed digital/analog services such as hybrid fiber 20 coax (HFC) and newer forms of mixed cable TV, this is considered a transitional state and dealt with as atemporary add-on to the all digital system of the presentinvention. The signal from the hybrid fiber coax isprovided directly to a set-top electronics 40 or to a 25 network interface unit 32/set-top electronics 40 combination. Two ports are required to connect to thehome network 10, one for the network interface unit 32and one for the set-top electronics 40. A bypass isprovided in certain preferred embodiments to link the 30 analog signals across to the audio/video circuits of the set-top electronics 40.

The home network 10 is controlled via hand heldcommander or computer keyboard to software running at thelocal terminals, such as the personal computers 20, or 35 set-top electronics 40. Control software local to each home terminal manages source availability, source 13 selection, path management by communication with thenetwork interface units 32 and external gateways. Theexternal network protocols are buffered in the networkinterface units 32 to provide a standard interface to theterminals on the home network 10. Figure 8 depicts onean example of a user interface. In this embodiment, thehome network 10 is transparent and the user is only awareof it indirectly from the number of connected services.

Figure 4 is a block diagram depicting a singlenetwork interface unit 32 coupled by the internal network34 to a single set-top electronics unit 40. Theremaining portions of the home network 10, including theswitching hub 38, are not shown in Figure 4 for purposesof illustration and explanation.

The network interface unit 32 has one or morenetwork interface modules 50 that interface the networkinterface unit 32 to. a particular external network. Inthe example of Figure 4, the network interface module 50provides an interface to an external network that carriesMPEG video data. The MPEG video data is provided to aninternal network interface device 52 that prepares thedata for transport over the internal network 34. Incertain preferred embodiments, the internal network 34 isan Ethernet network, so that the internal networkinterface device 52 is an Ethernet interface device.

The architecture of the present invention assumesthat for some networks a first stage demultiplexing atthe network interface unit 3 2 is necessary to stay withina definable bandwidth limit (one stream) rather than anarbitrary bandwidth set by the construction of theincoming stream (multiple streams). Making theassumption that MPEG-2 video is being used, there is ademultiplexing from a multiple program transport streaminto a single program transport, as defined in the MPEG-2specification. This is performed by an MPEG transportchip 54, such as the 9110B chip commercially available 14 10 15 20 25 30 from C-Cube. (A second stage demultiplexing to separatethe video, audio and other data still occurs in the set-top electronics, while decoding is preferably onlyperformed at the display terminal or computer.) Withthis approach, it is not necessary to send high bandwidthstreams throughout the house and the terminals in thehome 3 6 need see only a standardized single programinterface. Compression is required for video generatedin the home, e.g. security front door camera or videoconference camera.

All the external network interfacing, decryption,access control, demultiplexing to a single programstream, etc., is performed by the network interfacemodule 50. Thus, the network interface module 50 buffersthe home network hardware and software from thepeculiarities of the attached external network. Multipledifferent programs require multiple network interfacecrossbar connections whether from providers. . In certain embodiments, provided with two connections to the crossbar, providingtwo programs received from the same external network.

The MPEG transport chip 54 performs the MPEG clockrecovery and provides the recovered 27 MHz clock and theselected program to an internal network connection 56.The 2 7 MHz clock is received by an MPEG to networksynthesizer 58 and converted to a '10 MHz clock, forexample, when the internal network 34 is a 10base-TThe 10 MHz clock, as well as theare provided to a conventionalIsuch as an Ethernet transceiver) connected to the internal network 34. The synthesizer 58acts to lock the Ethernet clock to the recovered MPEGclock. When the packet of data is transmitted from thenetwork interface unit 32 to the set-top electronics 40,the set-top electronics 40 is locked to the recoveredMPEG data at 27 MHz. At the set-top electronics 40, the one or multiplea dual module is

Ethernet network,selected programtransceiver 60 35 15 27 Mhz clock is regenerated from the Ethernet 10 MHzclock fay another synthesizer.

The data is received in the set-top electronics 40by a network interface device 62 that includes a networkinterface 64. The 10 MHz clock recovered by the networkinterface 64 from the data stream off the network 34 isgated through gate 66 to a network to MPEG synthesizer 68. Gating is needed so that the locking function isperformed only when there is a packet of data present.The 10 MHz clock is converted to a 27 MHz clock providedto an MPEG decoder 70 and a video decoder/encoder 72.The selected program is provided by the network interface64 to the MPEG decoder 70, which decodes the MPEG dataand provides it to the video decoder/encoder 72. Thedata stream is converted by the video encoder 72 to aformat (e.g., NTSC or SVideo) suitable for use by adisplay device, such as a television. The video decoderos for the case (HFC) where there may be an NTSC analogsignal to digitize and merge with on-board graphicshardware .

The network 34 in Figure 4 is depictedschematically, and it should be understood from theprevious description that the video data may be placed onthe network 34 through the hub 42, but that a directcircuit of the network interface unit 32 and the set-topelectronics 40 through the direct circuit crossbar 44 ofthe network 34 is preferred to provide a jitter freetransfer of video data.

Figure 5 is a more detailed diagram of an exemplaryembodiment of the network interface device 62 of the set-top electronics 40 depicted in Figure 4. The networkinterface device 62 includes the network synthesizer 68coupled to a program logic device operating as the gatingdevice 66. The network synthesizer 68 may be implementedby a commercially available chip, such as the MC145151manufactured by Motorola. The program logic device 66 16 may be implemented by a commercially available chip, suchas the MC7958, also manufactured by Motorola. A voltagecontrolled crystal oscillator 80 operates at 27 MHz and.provides its signal to the program logic device 62, whichgates the 10 MHz signal to the synthesizer 68 when thereis a received data packet. The synthesizer divides downthe 10 MHz and 27 MHz frequencies to a common frequencywhich is fed into a phase detector of the synthesizer 68.The output of the phase detector of the synthesizer 68 isprovided as a control signal to the voltage controlledcrystal oscillator 80 to adjust the local frequency up ordown to lock to the incoming Ethernet frequency.

The signal informing the program logic device 66 ofthe receipt of a data packet, and the 10 MHz clock, areprovided by a serial interface adapter 82 serving as areceive enable. A commercially available productsuitable for the serial interface adapter is Am7992B,manufactured by Advanced Micro Devices.

The data stream is received through atransformer/filter 84, such as one commercially availablefrom Pulse Engineering, the PE68026. Collisioninformation is also received through anothertransformer/filter 86, which can be the same type oftransformer/filter as 84. The received data is providedto a first network transceiver 88, such as a twisted pairEthernet transceiver plus (Am79C100). The output of thefirst network transceiver 88 (the received data) is madeavailable to the receive enable 82 and a controller 90.The controller 90 may be a commercially availableproduct, such as the single-chip Ethernet controllerAm79C970 (manufactured by Advanced Micro Devices). Thecontroller 90 is coupled to a bus 92, such as aperipheral component interconnect (PCI) bus, forproviding the received data from the network 34 to theMPEG decoder 70 of the set-top electronics 40. 17 A second network transceiver 92 is coupled to the controller 90, and may be implemented by the same type of transceiver as 88. The second network transceiver 92 provides the transmit path for data from the controller 90 to the network 34 through the transformer/fliter 84.

Collision information is routed throughtransformer/fliter 86 and the second transceiver 92 tothe controller 90.

Figure 6 is a more detailed diagram of the internalnetwork connection 56, which has an MPEG to networksynthesizer 58 that synthesizes the 10 MHz clock from the27 MHz MPEG clock recovered by the MPEG transport chip 54(see Figure 4). A crystal oscillator 96 is coupled tothe synthesizer 58 to provide a 10 MHz signal. Incertain embodiments, the crystal oscillator 96 is a 20MHz oscillator, and the frequency generated by thesynthesizer is 20 MHz, which is then simply divided to 10MHz at the receiver (the set-top electronics 40) . Acommercially available synthesizer is the MC145145-2,manufactured by Motorola.

The 10 MHz clock is provided to a microprocessorinterface 98, which serves as interface for amicroprocessor 100. The microprocessor interface 98,with the microprocessor 100, form the transceiver 60 thatconnects to the internal network 34 through atransformer/filter 102. The microprocessor interface 98may be, for example, a MC6816 0 chip manufactured byMotorola, and the microprocessor may be a MC68EN360, alsomanufactured by Motorola. The transformer/f ilter 102 maybe the same type as transf ormer/f ilters 84, 86 of Figure5 . .

The separation of the network interface unit 3 2 fromthe set-top electronics 40 provides a number ofadvantages, as described earlier. The functions(responsibilities) of the conventional set-top boxes withintegrated network interface units are divided in 18

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embodiments of the present invention. For example, inpreferred embodiments, the network interface unit 32 isresponsible for performing external network specificinterfacing, tuning demodulation, and error correction. 5 It provides external network specific video descrambling and encryption/decryption (credit card number, userpassword, etc.) . The network interface unit 32 alsoprovides an external network specific program guide.Additionally, it performs MPEG transport demultiplexing 10 to a single stream and MPEG reference clock recovery. In preferred embodiments of the invention, the networkinterface unit provides home network Ethernet interfacingand MPEG/Ethernet clock locking. It also provides thesoftware to support the external network and home network 15 protocols for multiple streams and multiple users. The network interface unit also has the software to act asthe gateway for the home network and control thebuffering of data as necessary.

The set-top electronics 40 essentially acts as an 20 application computer with audio, video, graphic and analog television interface, in preferred embodiments.For example the set-top electronics provides the homenetwork specific interfacing and data buffering asnecessary. It provides Ethernet clock/MPEG clock locking 25 in preferred embodiments. The set-top electronics 40 decodes MPEG video and audio to recover digitalaudio/video. It performs digital to analog conversionfor audio and video, and supports commands from aninfrared remote control. The set-top electronics 40 30 provides support for analog video input (NTSC). It interfaces printers, game ports, etc., and supports bootlevel operating system and is able to down load a fullsystem from an external network. The set-top electronics40 supports application programs and communications 35 through the network interface units to a network provider and program video server. 19

Figure 7 is a block diagram depicting in more detailan exemplary embodiment of the hub 42 and direct circuitcrossbar 44 arrangement of the present invention and itsconnection with a network interface unit 32 and set-topelectronics 40. The direct circuit crossbar 44 and 42selectively provide either a direct circuit between aparticular network interface unit 32 and a set-topelectronics 40, or a simple network connection throughthe hub 42 for these units. In Figure 7, only portionsof the network interface unit 32 and the set-topelectronics 40 are depicted, for purposes of illustrationand explanation.

In preferred embodiments of the present invention,the hub 42 is a relatively simple and inexpensive hub,since it does not include any sort of packet routingswitch or store and forward switch. There is nointelligence that examines the traffic and dynamicallyswitches the hub according to the transmit and receiveaddresses as in hubs that have packet routing switches.

Although only one network interface unit 32 and oneset-top electronics 40 are shown directly connected inFigure 7, any number of directly connected pairs may beconnected by the direct circuit crossbar 44, depending onthe size of the crossbar 44. The network interface unit32 and the set-top electronics 40 are each shown withfive pin positions or connections, each of theconnections being a pair. This coincides with aconventional telephone plug, the telephone RJ45, whichhas ten pin positions.

The internal network 34 provides the connectionbetween the network interface units 32, the set-topelectronics 40 and the direct circuit crossbar 44. Inpreferred embodiments, the internal network 34 is 10 or100base-T Ethernet.

The selection of a network connection or a directcircuit between the network interface unit 32 and the 20

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set-top electronics 40 is established by a number ofswitches 108, which are depicted in Figure 7 with lettersuffixes to distinguish them from each other in thefollowing description. In the example of Figure 7, the 5 network interface unit 32 and the set-top electronics 40 are to be directly connected with one another, with thenetwork interface unit 32 transmitting data to the set-top electronics 40. A microprocessor 110 serves as thecontroller for the direct circuit crossbar 44 and 10 controls the positions of the switches 108 in response to user commands that require a direct circuit to perform.For example, a user may choose to watch a movie from avideo on demand service and therefore makes thisselection on a hand-held remote control. The 15 microprocessor 110, in response to this selection, will then change the positions of the switches 108 toestablish a direct circuit between the network interfaceunit 32 that is connected to the external network thatcarries the video on demand service, and the set-top 20 electronics 40 that is coupled to the television receiver on which the user desires to view the movie.

In this case, switch 108a is moved to itsillustrated position to connect the transmit lines oftransceiver 88 of the network interface unit 32 to line 25 112 of the direct circuit crossbar 44. The transmit lines of transceiver 88 are no longer connected to thenetwork at the Txl port of the hub 42. Similarly, thereceive lines of the transceiver 92 of the set-topelectronics 40 are connected through switch 108g to the 30 same line 112 of the direct circuit crossbar 44. With this direct circuit now established, data entering thehome through the network interface unit 3 2 is notbroadcast over the network via the hub 42, but instead isprovided directly to the set-top electronics 40 at the 35 location where the data will be used. 21

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10 15 20 25 30

Although the direct circuit established by thedirect circuit crossbar 44 provides an excellent pathwayfor data from the network interface unit 32 to the set-top electronics 40, it may occur that not all of the datacoming into the network interface unit 32 is meant forthe set-top electronics 40. For example, it is possiblethat e-mail is received over this particular networkinterface unit 32, and the homeowner wants e-mail to bedirected to a personal computer, and not to a television.However, there is no connection to the network 34 due tothe direct circuit once a direct circuit is established.

To solve this problem, the set-top electronics 40examines the addresses of the data packets it receivesand performs a routing function' for data that is notmeant for this set-top electronics 40. The data is re-routed by the set-top electronics 40 onto the network 34through the hub 42. This re-routing by the end pointconnection (the set-top electronics 40 in this example)avoids the need for the system to use an expensive andcomplicated router. The set-top electronics 40 has amicroprocessor 120 and associated memory 122 to identifyand route the data packets back to the network 34.

The direct circuit between the network interfaceunit 32 and the set-top electronics 40 provides a jitter-free connection for video data, but the re-routing ofother data into the network 34 through the hub allowsmore than one type of data to be carried into the home bythe network interface unit 32. Once the direct circuitbetween a network interface unit 32 and a set-topelectronics unit 40 is established, collision detectionis required by the set-top electronics 40 to allow it totransmit to the hub 42. The set-top electronics 40 needsto learn of collisions and re-transmit the data to thenetwork 34 if such collisions occur.. The networkinterface unit 32 can be set, in certain embodiments, todisable collisions because they cannot occur on the 35 22

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10 15 20 25 30 direct circuit. However, in certain embodiments, in boththe network interface unit port and the set-topelectronics port (to the network 34 through the crossbar44) , the same collision pair is included for convenience.

In certain preferred embodiments, one of the fivepairs of wires is available to provide picture-in-picturecapability for the system. For example, the networkinterface unit 32 may provide a second stream of datathrough another transceiver 88a over a second pair oftransmit wires onto a separate crossbar connection line114. The set-top electronics 40, which has anothertransceiver 88a also connected to line 114, receives thissecond stream of data through the direct circuit toprovide a picture-in-picture on a television screen.Thus, both pictures may be provided without jitter byseparate direct circuits.

In certain preferred embodiments, of the presentinvention, the crossbar switches 108 are implemented byan. analog MOS array of transistors, controlled inresponse to signals from the controller 110. This isexemplary only, however, as other embodiments employswitches of different design, as appreciated by one ofordinary skill in the art.

Although the description of the invention depictsthe arrangement with certain logical distinctions of thefunctionality of various elements, these logicaldistinctions may be different in other embodiments. Forexample, the hub 42 is described as connected to theinternal network. However, the hub 42 may also belogically considered as part of the internal network, oreven forming the network, with the remaining wiringforming means for attaching end terminals to the hub 42.One of ordinary skill in the art, therefore, willappreciate that the logical distinctions depicted anddescribed in the present specification are exemplaryonly. 35 23

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The separation of the network interface unit and theset-top electronics according to the present inventionprovides a relatively inexpensive connection of amultitude of devices to each other within the -home, and5 to the outside world.

Although the present invention has been describedand illustrated in detail, it is clearly understood thatthe same is by way of illustration and example only andis not to be taken by way of limitation, the spirit andscope of the present invention being limited only by theterms of the appended claims. 10