Abstract:
A multimedia apparatus is described comprising: a tuner for tuning to a carrier frequency and down-converting a frequency-modulated multimedia signal to a baseband multimedia signal; a selectable protocol module including QAM/MPEG logic and Data Over Cable Service Interface Specification (“DOCSIS”) logic configured to receive the baseband multimedia signal; and selection logic configured to select the QAM/MPEG logic for processing a first signal having a first signal format to produce a first processed signal, the selection logic further configured to select the DOCSIS logic for processing a second signal having a second signal format to produce a second processed signal.

Description:
BACKGROUND 
     1. Field of the Invention 
     This invention relates generally to the field of multimedia systems. More particularly, the invention relates to a multimedia system capable of selecting between different network protocols for transmitting and receiving data and multimedia content. 
     2. Description of the Related Art 
     A prior art system for receiving a digital multimedia signal is illustrated in FIG. 1 a . As illustrated, one or more tuners  120 ,  121  are configured to lock on to video signals  100 ,  101  transmitted at a carrier frequency and down-convert the signals to baseband. Quadrature Amplitude Modulation (“QAM”) demodulators  130 ,  131  demodulate the baseband signals to extract the underlying digital data. As is known in the art, QAM is a modulation technique employed by cable and satellite providers that generates four bits out of one baud. For example, a 600 baud line (600 shifts in the signal per second) can effectively transmit 2,400 bps using this method. Both phase and amplitude are shaped with each baud, resulting in four possible patterns. 
     The demodulated signal is then transmitted to conditional access (“CA”) subsystems  140 ,  141  which prevent channels/content from being transmitted on the system which the user does not have the right to receive (e.g., subscription-based content such as HBO or pay-per-view channels). CA subsystems  140 ,  141  are well known in the art and are currently manufactured by only a small group of companies including Scientific Atlanta,™ Motorola,™ General Instrument™ and DVB™. 
     If the CA subsystem  140 ,  141  allows the user to view a particular channel then multimedia content (i.e., audio and/or video content) from the channel is transmitted over a system bus  151  (via bus interface  150 ) to a mass storage device  160 . An MPEG-2 decoder module  170  coupled to the system bus  151  decodes/decompresses the multimedia content before it is rendered on a multimedia rendering device  135  (e.g., a television). 
     Prior art systems may also utilize a main memory  126  for storing instructions and data and a central processing unit (“PU”)  125  for executing the instructions and data. For example, the CPU may provide a graphical user interface displayed on the television, allowing the user to select certain television or audio programs for playback and/or storage on the mass storage device  120 . 
     The system illustrated in FIG. 1 a  is capable of concurrently receiving, decoding and storing multimedia content from two independent broadcast channels (i.e., via tuners  120  and  121 ). One limitation of this system, however, is that it does not provide a return channel for two-way communication. As such, users are unable to transmit data back to the cable or satellite provider or otherwise interact with the multimedia content. 
     To address these limitations, the prior art system illustrated in FIG. 1 b  includes a separate modem unit  190  comprised of a tuner  122  for receiving data, a QAM module  132 , and a transmitter/modulator unit  190  for transmitting data over a network (e.g., the Internet). As indicated in FIG. 1 b , the QAM module  132  is configured to support the Data Over Cable Service Interface Specification (“DOCSIS”), a set of accepted standards for transferring packetized data over cable TV networks. Thus, using the system of FIG. 1 b , a user is able to concurrently receive two cable broadcast channels while communicating over the Internet (e.g., sending email, browsing Web pages, downloading interactive content related to a particular TV program, . . . etc). 
     While the modem unit  190  provides the benefit of two-way communication, it also generates a significant additional cost as a result of the third system tuner  122 , third QAM module  132 , third CA subsystem  142  and the transmitter/modulator unit  190 . Moreover, because the legacy systems shown in FIGS. 1 a-b  rely on proprietary technology (such as CA subsystems developed by third parties), cable providers are limited in their ability to modify the underlying protocols used to transmit multimedia content to the end user. As such, new transmission techniques/protocols which would allow cable providers to transmit content in a more flexible, efficient and intelligent manner may not be employed. For example, using a packet-switched protocol such as DOCSIS to transmit and receive multimedia content (as well as data), cable operators would be able to dynamically route content to end users more efficiently and would have the flexibility to implement their own security mechanisms (e.g., those used for secure communication over the Internet). 
     Accordingly, what is needed is a system and method for receiving and transmitting data and multimedia content over a cable network in a more flexible, efficient and intelligent manner. What is also needed is a system which is backwards-compatible with currently-existing network protocols and standards and which is less costly to manufacture than current systems, while providing at least the same level of functionality as current systems. 
     SUMMARY OF THE INVENTION 
     A multimedia apparatus is described comprising: a tuner for tuning to a carrier frequency and down-converting a frequency-modulated multimedia signal to a baseband multimedia signal; a selectable protocol module including QAM/MPEG logic and Data Over Cable Service Interface Specification (“DOCSIS”) logic configured to receive the baseband multimedia signal; and selection logic configured to select the QAM/MPEG logic for processing a first signal having a first signal format to produce a first processed signal, the selection logic further configured to select the DOCSIS logic for processing a second signal having a second signal format to produce a second processed signal. 
     Also described is a multimedia communication system comprising: a communication channel configured to switch between a first mode in which the communication channel receives and decodes a first multimedia signal using MPEG logic, and a second mode in which the communication channel transmits and receives data and/or multimedia content according to the Data Over Cable Service Interface Specification (“DOCSIS”) standard. 
     Also described is a method implemented by a multimedia service provider for transitioning to a Data Over Cable Service Interface Specification (“DOCSIS”) communication standard comprising: providing subscribers with a first type of multimedia system having one or more selectable protocol modules, the selectable protocol modules being capable of selecting between a legacy communication standard and a DOCSIS communication standard for transmitting/receiving data and/or multimedia content; and switching from the legacy communication standard to a DOCSIS-only communication standard to transmit/receive multimedia content and/or data; and 
     providing new subscribers with a second type of multimedia system having one or more DOCSIS modules capable of transmitting/receiving data and/or multimedia content according to the DOCSIS standard. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     A better understanding of the present invention can be obtained from the following detailed description in conjunction with the following drawings, in which: 
     FIGS. 1 a  and  1   b  illustrate prior art multimedia receiver, storage and playback systems. 
     FIG. 2 a  illustrates a system for receiving and transmitting multimedia content and data according to one embodiment of the invention. 
     FIG. 2 b  illustrates a system for receiving and transmitting multimedia content and data according to another embodiment of the invention. 
     FIG. 2 c  illustrates a system for receiving and transmitting multimedia content and data according to another embodiment of the invention. 
     FIG. 3 illustrates multimedia and data bandwidth allocations which may be achieved using various embodiments of the invention. 
    
    
     DETAILED DESCRIPTION 
     In the following description, for the purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the invention may be practiced without some of these specific details. In other instances, well-known structures and devices are shown in block diagram form to avoid obscuring the underlying principles of the invention. 
     Embodiments of a Selectable Mode Multimedia System 
     As shown in FIG. 2 a , one embodiment of the invention is comprised of a first set of modules for tuning to and decoding a standard multimedia broadcast, including a tuner  120 , a QAM module  130  and a CA module  140 . Unlike prior art systems, however, the system illustrated in FIG. 2 a  shares the second tuner  222  and CA module  242  between a DOCSIS modem and a multimedia receiver/decoder channel. More specifically, the second set of components includes a selectable protocol module  230  which includes standard MPEG-2 logic  234  for processing multimedia cable/television channels and DOCSIS logic  235  for processing packetized data according to the DOCSIS standard. Both the MPEG-2 logic  234  and the DOCSIS logic  235  may share QAM demodulation logic  236  (the former for processing standard MPEG-2 video streams). It should be noted, however, that the DOCSIS logic  235  may employ various different modulation techniques while still complying with the underlying principles of the invention. In one embodiment, selection logic  251  selects between the MPEG-2 logic  234  and the DOCSIS logic  235  based on the actions of the user and/or the configuration of the multimedia system. 
     In operation, if a user is watching a first cable channel via tuner  120  and decides to concurrently record a second cable channel or watch the second channel on a separate display or picture-in-picture window, the second tuner  222  will lock on to the second channel responsive to the user&#39;s request and the selection logic  251  will select the MPEG-2 logic  234  and the QAM logic  236  for processing the incoming multimedia content from the second channel. The CA module  242  of this embodiment will then operate on the incoming multimedia content as described above (i.e., providing access to the channel/content only if the user has the right to view it). In one embodiment (not shown) the same CA module may be used to support both the first cable channel and the second cable channel (e.g., the CA module may be double-clocked to support the increased throughput). 
     By contrast, if the user chooses to browse Web pages on the Internet, send an email or perform any other data transactions while watching a cable channel via tuner  120 , the selection logic  251  will select the DOCSIS module  235  for communicating DOCSIS-formatted data over the cable provider&#39;s network using the modulator unit  292  and the tuner  222  (for transmitting and receiving data, respectively). The DOCSIS module  235  may also employ the QAM logic  236 , depending on how the incoming data is formatted by the service provider. In addition, because the CA module is not needed for receiving/transmitting DOCSIS-formatted data, the selection logic  251  may select the DOCSIS data bypass signal  281  to bypass the CA module  242  entirely. 
     Thus, unlike the system shown in FIG. 1 b , the system illustrated in FIG. 2 a  shares a single tuner  222 , a single CA module  242  and a single selectable protocol module  230  between a multimedia receiver channel (e.g., for receiving cable channels) and a DOCSIS channel, thereby reducing system cost while at the same time maintaining the same level of functionality as in prior systems. 
     A related embodiment of the invention, illustrated in FIG. 2 b , is comprised of a second selectable protocol module  231  which, responsive to selection logic  250 , switches between MPEG-2 logic  232  for receiving multimedia content and DOCSIS logic  233  for processing packetized DOCSIS data/content. Because only one upstream communication channel is typically required, a second modulator/transmitter (such as modulator/transmitter  292 ) is not associated with the second selectable protocol module  231  (although such a configuration is nonetheless considered within the scope of the present invention). Thus, the embodiment illustrated in FIG. 2 b  provides two separate communication channels (one unidirectional channel and one two-way channel) which process content and data under the DOCSIS standard when selected by selection logic  250 - 251 . As in the previous embodiment, when the DOCSIS logic  233 ,  235  is selected DOCSIS data bypass signals  280 ,  281  may be selected to bypass the CA modules  240 ,  242 , respectively. Moreover, as with the embodiment illustrated in FIG. 2 a , the DOCSIS logic  232 ,  235  may or may not use the QAM logic  237 . 
     The selection logic  250 ,  251  described herein may be embodied in software executed by the CPU  225  and configured to select between MPEG-2 logic  232 ,  234  and DOCSIS logic  233 ,  235  based on the actions of the user. Alternatively, the selection logic  250 ,  251  may be embodied in any combination of hardware (e.g., an application-specific integrated circuit (“ASIC”)), software and/or firmware while still complying with the underlying principles of the invention. 
     One benefit of the embodiments described above is that they provide cable operators and other multimedia content providers with the ability to transmit video (e.g., cable channels) using the DOCSIS standard without the need for a CA module for security. In order to provide security without a CA module, in one embodiment, video and other content/data may be transmitted securely by content providers using open encryption technologies such as Secure Sockets Layer (“SSL”) encryption or Transport Layer Security (“TLS”) encryption. It should be noted, however, that various other point-to-point encryption technologies may be employed while still complying with the underlying principles of the invention. 
     In addition, because the embodiments described above are capable of receiving multimedia content transmitted from both standard channels (e.g., MPEG-2/QAM channels) and DOCSIS channels, the transition from current communication schemes to an all-DOCSIS communication scheme, illustrated in FIG. 3, may be accomplished seamlessly while, at the same, the overall quality of service to the end user will improve. For example, the current bandwidth allocation for data/content transmitted over cable provider networks is represented by bandwidth allocation  304 , with approximately ½ of the available bandwidth being allocated to analog transmissions  304  and the majority of the remaining ½ being consumed by standard digital transmissions  302  (i.e., only a small fraction of the bandwidth  300  is currently used for DOCSIS transmissions, primarily to support cable Internet services). 
     As indicated by the intermediate bandwidth allocation  306 , however, cable operators may use embodiments of the invention described herein to seamlessly phase out the digital and analog multimedia transmissions, and to rely on DOCSIS (or some other packet-switched standard) for transmitting both data and multimedia content. Eventually, as represented by bandwidth allocation  306 , cable operators may eventually switch to a DOCSIS-only transmission scheme. Moreover, once the transition to DOCSIS is complete, content providers can provide new users with the embodiment illustrated in FIG. 2 c , comprised of dual DOCSIS modules  290 ,  292  for processing DOCSIS data/content transmissions and a modulator/transmitter  292  for providing upstream data/content transmissions. Typically only one modulator will be required; however, in one embodiment a second upstream modulator (not shown) may be associated with DOCSIS module  292  and tuner  220 . 
     Embodiments of the invention may include various steps, which have been described above. The steps may be embodied in machine-executable instructions which may be used to cause a general-purpose or special-purpose processor to perform the steps. Alternatively, these steps may be performed by specific hardware components that contain hardwired logic for performing the steps, or by any combination of programmed computer components and custom hardware components. 
     Elements of the present invention may also be provided as a computer program product which may include a machine-readable medium having stored thereon instructions which may be used to program a computer (or other electronic device) to perform a process. The machine-readable medium may include, but is not limited to, floppy diskettes, optical disks, CD-ROMs, and magneto-optical disks, ROMs, RAMs, EPROMs, EEPROMs, magnet or optical cards, propagation media or other type of media/machine-readable medium suitable for storing electronic instructions. For example, the present invention may be downloaded as a computer program product, wherein the program may be transferred from a remote computer (e.g., a server) to a requesting computer (e.g., a client) by way of data signals embodied in a carrier wave or other propagation medium via a communication link (e.g., a modem or network connection). 
     Throughout this detailed description, for the purposes of explanation, numerous specific details were set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the system and method may be practiced without some of these specific details. For example, while the embodiments described above focus on the DOCSIS standard, the underlying principles of the invention may be implemented using various other packet-based protocols (e.g., TCP/IP). Similarly, various compression algorithms other than MPEG-2 may be employed while still complying with the underlying principles of the invention (e.g., MPEG-4, RealVideo® 8). In other instances, well known structures and functions were not described in elaborate detail in order to avoid obscuring the subject matter of the present invention. Accordingly, the scope and spirit of the invention should be judged in terms of the claims which follow.