METHOD AND SYSTEM FOR PROVIDING BI-DIRECTIONAL COMMUNICATIONS TO A BROADBAND NETWORK WITHOUT DEGRADING DOWNSTREAM BANDWIDTH

Abstract: In a communications network having a primary communication path, a bi-directional secondary communication path. The primary communication path delivers downstream signals from a headend to a subscriber location. The secondary communication path transmits return signals from the subscriber location to the headend, and also provides an out-of-band transmission path for downstream signaling. The present invention meets the needs in the art by allowing return signals to be transmitted upstream over the secondary communication path, thereby avoiding the consumption of bandwidth in the primary communication path. Moreover, downstream signals which do not need to be transmitted in the downstream band can be transmitted over the secondary communication path, further reducing the consumption of bandwidth in the primary communication path.

Description: METHOD AND SYSTEM FOR PROVIDING BI-DIRECTIONAL COMMUNICATIONS TO A BROADBAND NETWORK WITHOUT DEGRADING DOWNSTREAM BANDWIDTH FIELD OF THE INVENTION The present invention generally relates to the field of bidirectional broadband communications. More particularly, the present invention relates to communications networks which provide a secondary communication path for upstream and downstream transmissions. BACKGROUND OF THE INVENTION Cable television has become a staple product in many homes. An estimated 65% of all American households now receive cable service. Cable companies install extensive broadband networks to provide cable service to subscribers. A typical broadband network includes four main elements: a headend, a trunk system, a distribution system, and subscriber drops. The headend receives cable programming from many sources, including satellite, over-the-air local station signals, and terrestrial microwave links. The headend processes the received cable programming and delivers it over the trunk system, which is the main transmission artery of the broadband network. 2 The trunk system branches into a number of distribution systems. The distribution systems deliver the cable programming from the trunk system into individual subscriber areas. The distribution system is also called the "feeder." A distribution system terminates in a subscriber area at a distribution point, such as an optical network unit ("ONU"). A tap at the distribution point feeds a subscriber drop, which completes the connection from the distribution point to the subscriber location. Subscriber locations are typically houses or apartments. Often, an end-user device, such as a set-top box, is used within the subscriber location to decode signals for premium channels, pay-per-view broadcasts or the like. Generally, the signals carried over the broadband network are transmitted in a frequency spectrum of 5 MHz to 750 MHz (the "frequency spectrum"). The bandwidth of the frequency spectrum is largely driven by the bandwidth limitations of coaxial cable, the transmission line most commonly used in broadband networks today. As fiber optic cable gets pushed deeper into the subscriber area, the available frequency spectrum is expected to increase to over 1 GHz to help satisfy growing bandwidth demands. Broadband networks were originally designed to distribute signals in the "downstream direction" only (i.e., from the headend to the subscriber locations, also referred to as the "forward" path). Therefore, the component equipment of many older broadband networks, which includes amplifiers and compensation networks, is typically adapted to deliver signals in the downstream direction only. To transmit downstream content in the downstream direction, typical broadband networks provide a series of "channels" within the frequency spectrum, with each channel being 6 MHz in bandwidth. Each channel carries a particular transmission, such as a single television show. The channels are frequency division multiplexed in the 50 MHz to 750 MHz region of the frequency spectrum. For this 3 discussion, the 50 MHz to 750 MHz region of the frequency spectrum is termed the "forward band" or "downstream band." The advent of pay-per-view services and other interactive television applications is fueling the development of "two-way" or bi- directional communications networks. A bi-directional communications network provides for the transmission of "return signals." Return signals are any signals which are transmitted from the subscriber location back to the headend. Transmission from the subscriber location back to the headend is often referred to as the "upstream direction" or the "reverse path." Typically, a region of the frequency spectrum from 5 MHz to 40 MHz is used to transmit return signals in the upstream direction. For this discussion, the 5 MHz to 40 MHz region of the frequency spectrum is termed the "reverse band" or "upstream band." The typical communications network includes a demodulator at the headend or distribution point to separate the return signals in the upstream band from the downstream content in the downstream band. This technology has allowed cable companies to provide many new interactive subscriber services over the broadband network, such as impulse-pay-per-view (IPPV). Figs. 1 and IA help illustrate this bi-directional broadband technology. Fig. 1 is a functional block diagram of a typical cable network 100 which provides bi-directional communications over a single communication path. Fig. 1 is used to describe the flow of signals from a headend 102 (within the dashed line box) to an end-user device 104 located at a subscriber location and vice versa. To help envision the flow of signals, Fig. IA depicts a graphical representation of the frequency spectrum showing the signals in the downstream band 130 (from 50 MHz to 750 MHz) and the upstream band 134 (from 5 MHz to 50 MHz) of the existing cable network 100. Each block shown in Fig IA represents the signals being transmitted in the particular frequency range subsumed by that block. 4 For instance, the broadcast signals 128 are shown being transmitted in the downstream band 130. For ordinary broadcast transmission, a connection management system ("CMS") 108 at the headend 102 directs a video server 112 to transmit downstream content, such as television programming, to an asynchronous transport multiplexer switch ("ATM") 116. The ATM 116 establishes a path from the video server to an appropriate output port and transmits the downstream content to a broadband gateway 120. The broadband gateway 120 converts the downstream content into modulated signals 128 which can be transmitted downstream over a broadband network 124. The conversion by the broadband gateway 120 can include modulating the downstream content to an appropriate carrier frequency within the downstream band 130, and frequency division multiplexing the modulated downstream content into modulated signals 128 for transmission over the broadband network 124. The broadband network 124 then carries the modulated signals 128, in the downstream band 130, to subscribers in the cable network 100. At most subscriber locations, the broadband network 124 is terminated at the end-user device 104 which converts the modulated signals 128 to television programming for display on a television set. Those skilled in the art will appreciate that the end-user device 104 can be a set-top box, a cable-ready television set, a personal computer, or other device capable of de-multiplexing and demodulating the modulated signals 128. Moreover, the modulated signals 128 are not limited to television programming. The modulated signals 128 can be any form of information distributed by the cable network 100, such as Internet communications, music transmissions or the like. If a subscriber desires to purchase an IPPV movie, the subscriber can instruct the end-user device 104 to issue a request to the headend 102 to deliver the IPPV movie to the subscriber location. The 5 end-user device 104 converts the subscriber's instruction into a return signal 132, modulates, multiplexes, and transmits the return signal 132 over the broadband network 124 in the upstream band 134. Typically, the return signal 132 includes a unique identifier for the end-user device 104 which the headend 202 uses to deliver the IPPV movie to the particular subscriber location. Within the broadband network 124, diplexers are used to extract the return signal 132 from the frequency spectrum, and to transmit the return signal 132 to the demodulator 138. The demodulator 138 converts the return signal 132 into a baseband signal and forwards the baseband signal to a network router 142. For this discussion, the term "baseband" means a form of modulation in which signals are pulsed directly on a transmission medium without frequency division. The network router 142 then forwards the baseband signal to the CMS 108, via the ATM 116. The CMS 108 then directs the video server 112 and the ATM 116 to transmit the IPPV movie to the broadband gateway 120. At the broadband gateway 120, the IPPV movie is converted to IPPV signals 146 in a particular channel of the downstream band 130. Generally, the IPPV signals 146 are encoded to prevent unauthorized viewing. Then the broadband gateway 120 forwards the IPPV signals 146 to the broadband network 124, which delivers the IPPV signals 146 to the end-user device 104. Decryption information must be typically transmitted with the IPPV signals 146 to enable the end-user device 104 to decode and display the IPPV movie on the subscriber's television set. In existing broadband networks, the decryption information is generally transmitted in the same channel as the IPPV signals 146, which is commonly referred to as "in-band signaling." In-band signaling generally occurs in the following manner. The CMS 108 generates the decryption information 152 and 6 transmits it to the modulator 156. The modulator 156 modulates the decryption information 152 for transmission over the broadband network 124 and forwards the decryption information 152 to the broadband network 124. Under control of the CMS 108, the broadband network 124 multiplexes the decryption information 152 and the IPPV signals 146 into the same channel of the downstream band 130. As a result, a portion of the channel being used to transmit the IPPV signals 146 is used to transmit the decryption information 152. The consumption of the portion of the channel results in reduced bandwidth available for the IPPV signals 146. The broadband network 124 delivers the decryption information 152 and the IPPV signals 146 to the end-user device 104. Once received, the end-user device 104 demodulates and uses the decryption information 152 to decode and convert the encrypted IPPV signals 146 into a form which can be displayed on a television set at the subscriber location. Finally, the subscriber views the decoded IPPV movie on a television set. Those skilled in the art will appreciate that this described system is in widespread use in existing broadband networks. Unfortunately, there are several problems associated with the described system. One problem with the existing broadband network relates to the need for multiple subscribers to share the upstream band. The distributive nature of the broadband network topology forces the subscribers that receive signals from a particular distribution point to share the upstream band when the subscribers transmit return signals. In other words, the same frequency spectrum is used to service all of the subscribers, so when the subscribers transmit upstream, the upstream band must be further divided among each of the subscribers. Dividing the upstream band among the subscribers results in reduced bandwidth available to each subscriber for return signals. 7 Another problem with the existing broadband network relates to the in-band signaling. In-band signaling is undesirable because it leaves less bandwidth available for downstream communications in the downstream band. It is therefore desirable to transmit the decryption information out-of-band. Transmitting the decryption information out-of-band reserves the valuable downstream bandwidth for downstream communications which must be transmitted in-band, such as the IPPV movie discussed above. The existence of the problems identified above evidences a need for a bi-directional communications network which eliminates the need to transmit return signals from the end-user device to the headend in the upstream band. Moreover, a need exists for a bi-directional communications network which provides an out-of-band downstream communication path for non- video content, such as video signaling. One attempt to create an improved bi-directional communications network appears in Bodeep et al, U.S. Patent No. 5,528,582. Bodeep et al. describes a broadband network having a primary communication path, and a second communication path. The primary communication path of Bodeep et al. equates to the single communication path used by existing broadband networks. Downstream communications, including television programming and the like, are carried over the primary communication path to subscriber locations. An end user unit at a subscriber location transmits return signals in the downstream direction of the primary communication path. The system described by Bodeep et al. may transmit return signals in either the upstream band or a portion of the downstream band, but always in the downstream direction. Accordingly, each end user unit transmitting return signals consumes a portion of the frequency spectrum. In Bodeep et al., a series of "mini-fiber nodes" ("MFNs") are deployed at several locations along the primary communication path and downstream of a plurality of subscribers. The MFNs convert the return signals for communication upstream over the second communication path. The MFN which is downstream of a subscriber location collects the return signals transmitted by the end user unit at that subscriber location. The MFN then filters the return signals to remove any downstream content and transmits the return signals back to the headend over the second communication path. The second communication path can be a dedicated fiber optic cable between the MFN and the headend. The system described by Bodeep et al. suffers from a series of problems. First, the return signals from each end user unit may be transmitted in the downstream direction in the downstream band. As a result, Bodeep et al. envisions the use of some of the available bandwidth in the downstream band to transmit return signals. Currently, cable service providers oppose efforts to use the downstream bandwidth for return signals. Such use reduces the bandwidth available for television channels, thereby reducing the number of television channels which can be offered. One area of competition among cable service providers is the number of television channels offered. Another problem with Bodeep et al. resides in the fact that an individual MFN services multiple subscribers. All of the subscribers can transmit return signals. If transmitting in either the downstream band or the upstream band, each of the subscribers must be allocated a portion of the available frequency spectrum for return signals. Therefore, Bodeep et al. perpetuates the problem of subscribers having to share the available bandwidth of the frequency spectrum in order to transmit return signals. Yet another problem with Bodeep et al. is that the system described still transmits return signals by modulating them into part of the frequency spectrum. The system of Bodeep et al. creates two types 9 of downstream communications: (1) return-signals and (2) ordinary downstream communications, such as broadcast television programming. Combining return signals with ordinary downstream communications requires the use of additional broadband communications components, such as additional modulators and demodulators at the end user unit. The Bodeep et al. system retains the need for such components to combine and to separate the return signals from the ordinary downstream communications. Therefore, Bodeep et al. does not provide a communications network which alleviates the need for modulators and demodulators in the end-user unit to transmit return signals. To summarize, existing bi-directional communications networks suffer from several problems. One such problem is multiple subscribers having to share the frequency spectrum when transmitting return signals to the headend. Another problem is that existing bidirectional communications networks generally transmit signaling, such as decryption information, in-band with video content. In-band signaling reduces the bandwidth available for additional downstream commumcations. Unfortunately, present attempts at improved bi-directional communications, such as the system of Bodeep et al., do not address these problems. Accordingly, a need exists for a bi-directional communications network that allows return signals to be transmitted to a headend without reducing the available bandwidth of the broadband communication network. SUMMARY OF THE INVENTION The present invention overcomes the problems identified above by providing a bi-directional secondary communication path to a communications network having a broadband primary communication path. The primary communication path delivers downstream signals 10 from a headend to a subscriber location. The secondary communication path transmits return signals from the subscriber location to the headend, and also provides an out-of-band transmission path for downstream signaling. The present invention meets the needs in the art by allowing return signals to be transmitted upstream over the secondary communication path, thereby avoiding the consumption of bandwidth in the primary communication path. Moreover, certain downstream signals, such as decryption information, which do not need to be transmitted in the downstream band can be transmitted to the subscriber location over the secondary commumcation path, thereby further reducing the consumption of bandwidth in the primary communication path. In one aspect, the present invention provides a system for transmitting a return signal from a subscriber location to a headend in a communications network. Downstream signals are transmitted from the headend to the subscriber location over a primary communication path. The system provides a secondary communication path, having an upstream direction and a downstream direction, for transmitting the return signals from the subscriber location to the headend. The system also provides an end-user device at the subscriber location. The end- user device has a first network interface connected to the primary communication path for receiving the downstream signal from the headend. The end-user device also has a second network interface connected to the secondary communication path for transmitting the return signal to the headend in the upstream direction. In this manner, the return signal is transmitted from the end-user device to the headend over the secondary communication path without consuming bandwidth in the primary communication path. In another aspect, the present invention provides an end- user device for use in a communications network. The commumcations network includes a primary communication path for delivering a 11 downstream signal to the end-user device. The end-user device includes a first network interface capable of receiving the downstream signal over the primary communication path. The end-user device also includes a second network interface capable of transmitting a return signal over a secondary communication path from the end-user device to the headend. In this manner, the return signal may be transmitted from the end-user device to the headend over the secondary communication path and avoid the consumption of bandwidth in the primary communication path. In yet another aspect, the present invention provides a communications network capable of delivering return signals over a secondary communication path and downstream signals over either the secondary communication path or a primary communication path. The communications network includes a headend for generating a downstream signal for distribution to a subscriber location. A first gateway in the communications network connects the headend to a broadband network, which may distribute the downstream signal to the subscriber location. An end-user device at the subscriber location has a first network interface connected to the broadband network and may receive the downstream signal. The end-user device may convert the downstream signal to a format which can be displayed. The end-user device also has a bi-directional second network interface capable of transmitting a return signal or receiving the downstream signal. A second gateway is connected to the second network interface of the end-user device and is capable of bi-directional commumcations. The second gateway may receive the return signal from the end-user device and deliver the return signal to the headend over a baseband network connected between the second gateway and the headend. Other aspects, features, and advantages of the present invention will become apparent upon reading the following description 12 of exemplary embodiments, when taken in conjunction with the drawings and the claims. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a functional block diagram of a communications network between a headend and a subscriber location. Fig. IA is a graphical representation of the frequency spectrum of the communications network of Fig. 1 showing the relative positions of signals in the downstream band and the upstream band. Fig. 2 is a functional block diagram of a communications network constructed in accordance with an exemplary embodiment of the present invention. Fig. 2A is a graphical representation of the frequency spectrum of a communications network constructed in accordance with . an exemplary embodiment of the present invention showing the relative positions of signals in the downstream band and the upstream band. Fig. 3 is a functional block diagram of an exemplary end- user device employed in the communications network of Fig. 2. Fig. 4 is a flow chart illustrating steps involved with bidirectional communications over the communications network of Fig. 2 in accordance with an exemplary embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS Generally, the present invention overcomes the limitations discussed in the background by creating a "secondary communication path" for return signals in a commumcations network having a "primary communication path." The primary communication path extends from a headend to an end-user device at a subscriber location. The secondary communication path is a bi-directional communication path between the end-user device at the subscriber location and the 13 headend. Advantageously, the secondary communication path carries return signals from the end-user device to the headend without consuming bandwidth in the primary communication path of the communications network. Referring now to the drawings, in which like numerals represent like elements throughout the several figures, aspects of the present invention and an exemplary operating environment will be described. Figs. 2 and 2A illustrate an exemplary embodiment of the present invention. Fig. 2 is a functional block diagram of a communications network constructed in accordance with an exemplary embodiment of the present invention. Illustrated is a communications network 200 which provides bi-directional communications between a headend 202 (within the dashed line box) and an end-user device 204 at a subscriber location through the use of a secondary communication path (the "out-of-band" path) 239. To help envision the flow of signals, Fig. 2A depicts a graphical representation of the frequency spectrum of the communications network 200 showing the relative positions of signals in the downstream band 222 (from 50 MHz to 750 MHz). Each block shown in Fig. 2 A represents the signals being transmitted in the particular frequency range subsumed by that block. For instance, the modulated signals 218 are shown being transmitted in the downstream band 222. In the downstream direction, the communications network 200 is similar to the bi-directional cable network 100 of Fig. 1. The CMS 208 directs the video server 212 to transmit television programming or other broadcast communications to the ATM 216. The ATM 216 establishes a path from the video server 212 to an appropriate output port, and forwards the broadcast communications to the broadband gateway 220. The broadcast communications can include cable television programming, Internet transmissions, audio 14 programming, a list of IPPV movies available for purchase by the subscriber, or any type of communications appropriate for transmission in the downstream direction of the broadband network 200. When received, the broadband gateway 220 converts the broadcast communications into modulated signals 218 which can be transmitted over the broadband network 224. The conversion can include modulating, frequency division multiplexing, or otherwise preparing the broadcast communications for transmission as modulated signals 218. The broadband gateway 220 then forwards the modulated signals 218 to the broadband network 224, which transmits the modulated signals 218 in the downstream band 222 to the subscriber's location. The end-user device 204 at the subscriber location receives the modulated signals 218 and converts them back into a form which can be displayed on an appropriate terminal device. For instance, the converted modulated signals 218 can be displayed by the end-user device 204 on a television set, a computer display monitor, or other appropriate terminal device at the subscriber location. The following discussion is an example of a typical scenario making use of the secondary communications path (the "out- of-band" path) 239 of the communications network 200. In this example, a subscriber at the subscriber location desires to receive an IPPV movie from the headend 202. Other examples will be apparent to those of ordinary skill in the art in which the subscriber can request to receive other communications, such as cable television programming, Internet transmissions, audio programming, or the like, from the headend 202. In accordance with this example, the subscriber instructs the end-user device 204, described in more detail below with respect to Fig. 3, to request the headend 202 to deliver the IPPV movie to the subscriber location. The subscriber's instruction can be in the form of a 15 remote control input or the like. In response, the end-user device 204 generates a return signal indicating that the subscriber desires to purchase the IPPV movie. The return signal can be a digital data packet containing information which enables the headend 202 to transmit the IPPV movie to the end-user device 204. The information can be a unique identifier associated with the end-user device 204 and an identifier for the IPPV movie. The end-user device 204, described in more detail below with respect to Fig. 3, supports the secondary communication path 239 between the end-user device 204 and the headend 202. The secondary communication path 239 allows the return signal to be carried from the end-user device 204 to the headend 202 without burdening the broadband network 224. In the exemplary embodiment, a connection 228 joins the end-user device 204 to a baseband gateway 232. The baseband network 238 joins the baseband gateway 232 to the headend 202. The end-user device 204, the connection 228, the baseband gateway 232, and the baseband network 238 together form the secondary communication path 239. Each of these elements is discussed in further detail below. In the exemplary embodiment, the end-user device 204 includes a baseband network interface 320 (Fig. 3) which supports the connection 228 between the end-user device 204 and the baseband gateway 232. The connection 228 can be any data transmission medium capable of transmitting signals between the end-user device 204 and the baseband gateway 232, such as coaxial cable, twisted-pair copper wire, fiber-optic cable or the like. The baseband gateway 232 can reside in a distribution component of the communications network 200 at the subscriber area, or in any other acceptable location. One example of an acceptable location for the baseband gateway 232 is within an optical network unit ("ONU") of a telecommunications system. 16 The baseband gateway 232 receives the return signal from the end-user device 204 over the connection 228. The baseband gateway 232 transmits the return signal over the baseband network 238 to a host terminal 236 located at the headend 202. The baseband network 238 can be any acceptable network architecture, such as an ethernet network or the like. The transmission medium for the baseband network 238 can be any acceptable transmission medium, such as fiber optic cable, coaxial cable or the like. The host terminal 236 interfaces the transmission medium of the baseband network 238 to the data network electronics of the headend 202. The return signal is then forwarded to the network router 240. The network router 240 of the exemplary embodiment can be the same device as the network router 142 of the existing cable network 100, shown in Fig. 1. The network router 240 then forwards the return signals to the CMS 208 via the ATM 216 or other data networking connection. In response to the receipt of the return signal, the CMS 208 directs the video server 212 to begin transmitting the IPPV movie. Also, the CMS 208 directs the ATM 216 to establish an appropriate connection to the broadband gateway 220. From the ATM 216, the IPPV movie is forwarded to the broadband gateway 220, which converts the IPPV movie to IPPV signals 248 for transmission over the broadband network 224. The broadband network 224 then distributes the downstream communications, including the IPPV signals 248, to the end-user device 204 at the subscriber location. Concurrently with the transmission of the IPPV signals 248, the CMS 208 generates and transmits decryption information associated with the IPPV signals 248 to the ATM 216. The decryption information can include a decryption key and incoming channel information to allow the end-user device 204 to properly receive the IPPV signals 248. The ATM 216 forwards the decryption information to the network router 240. The network router 240 formats the 17 decryption information in an appropriate transmission protocol, such as TCP IP, ATM, or the like, for transmission to the host terminal 236. The network router 240 forwards the decryption information to the host terminal 236, which prepares the decryption information for transmission to the baseband gateway 232 over the baseband network 238. To prepare the decryption information, the host terminal 236 can time division multiplex the decryption information with other information and convert the decryption information from electrical signals to optical signals (if appropriate) for transmission over the baseband network 238. With the decryption information converted to signals, the host terminal 236 transmits the signals over the baseband network 238 to the baseband gateway 232 in the subscriber area. The baseband gateway 232 receives the signals transmitted over the baseband network 238 and forwards the signals to the end-user device 204 at the subscriber location. As will be known to those skilled in the art, forwarding the signals can include converting the received signals from optical signals to electrical signals (if appropriate) and demultiplexing the electrical signals to extract the decryption information particular to the end-user device 204, or otherwise making the signals transmitted over the baseband network 238 usable by the end-user device 204. The end-user device 204 then uses the decryption information to decode the incoming IPPV signal 248 transmitted over the downstream band 222 and to present the IPPV movie to the subscriber. The foregoing example discussed the operation of the communications network 200 to service a subscriber's request for an IPPV movie. However, the present invention is not limited to the transmission of IPPV movies and those skilled in the art will appreciate that the communications network 200, including the secondary communication path 239, can be used to transmit other types of 18 communications, such as other cable television programming, Internet transmissions, audio programming, or the like. The communications network 200 of the exemplary embodiment differs from the cable network 100 shown in Fig. 1 in several ways. For instance, the secondary communication path 239 of the exemplary embodiment makes the demodulator 138 (Fig. 1) and the modulator 156 (Fig. 1) of the cable network 100 unnecessary. The exemplary embodiment uses the separate secondary communication path 239 between the headend 202 and the end-user device 204 for return signals and decryption information. Through the use of the secondary communication path 239, the exemplary embodiment avoids the need to modulate and demodulate upstream communications. Eliminating the need to modulate and demodulate upstream communications can result in a decreased cost of communicating in the upstream direction. Moreover, the secondary communication path 239 allows the exemplary embodiment to avoid transmitting return signals in the upstream band 244 of the broadband network 224. Consequently, the exemplary embodiment overcomes the problem in the art of multiple subscribers having to share the limited-bandwidth upstream band 244. Also, the exemplary embodiment eliminates the need for in-band signaling by providing the secondary communication path 239 for signaling. Removing the added burden of in-band signaling makes it possible to transmit additional downstream signals 256 in the downstream band 222. Although the exemplary embodiment is described with reference to a communications network protocol constructed in accordance with the Ethernet standard, other embodiments will become apparent to those of ordinary skill in the art. For instance, the secondary communication path could be supported by another networking architecture, such as asynchronous transmission mode, 19 cellular packet data, or frame relay. Accordingly, state-of-the-art networking techniques and protocols can be employed to give the secondary communication path a throughput in excess of hundreds of megabits per second, which is ample bandwidth to provide non-video content signaling to each of the subscribers in the broadband network 200. Fig. 3 helps illustrate the end-user device 204 component of the communications network 200. Fig. 3 is a functional block diagram of an exemplary end-user device 204 of the disclosed embodiment. The end-user device 204 includes five major functional components: a broadband network interface 302, a quadrature amplitude modulation ("QAM") demodulator 306, a controller 310, a video display terminal 314, and a baseband network interface 320. The components are illustrated as discrete boxes, but those skilled in the art will understand that the functions of one or more of the components can be integrated into one or more printed circuit boards or other electronic parts. Each of the components is described below in more detail. The controller 310 can be a microprocessor or microcontroller operative to control the flow of signals through the end-user device 204. The controller 310 can include software, firmware, logic arrays or other mechanisms for controlling the end-user device 204. Each of the other functional components of the end-user device 204 operates under control of the controller 310. The broadband network interface 302 receives downstream signals 324 from the broadband network 224 (Fig. 2). The downstream signals 324 can include broadcast television programming, IPPV movies, Internet transmissions, music signals or the like. Typically, the downstream signals 324 are electrical signals which are frequency division multiplexed and modulated for transmission over the broadband network 224 (Fig. 2). Accordingly, the broadband network 20 interface 302 demultiplexes the downstream signals 324 into individual channels or bands of information on multiple carrier frequencies. The demultiplexed downstream signals 324 are then demodulated by the QAM demodulator 306 to remove the carrier frequencies and otherwise prepare the downstream signals 324 for use at baseband by the end-user device 204. Once the downstream signals 324 are demodulated, the video display terminal 314 transforms the signals into output signals 328 which can be displayed on a television set. Those skilled in the art will understand that the output signals 328 can also be music signals for transmission to a stereo, digital signals for transmission to a computer, or any other form of output signal. The baseband network interface 320 connects the end- user device 204 to the connection 228 (Fig. 2) of the secondary communication path 239 (Fig. 2). The baseband network interface 320 is a bi-directional communications interface capable of transmitting and receiving data signals 332 to and from the headend 202. The data signals can be downstream signals or decryption information received from the headend 202 (Fig. 2), or return signals transmitted to the headend 202 (Fig. 2). In a preferred embodiment, the baseband network interface 320 includes an auxiliary connector 336 to allow a subscriber or field technician to make a second connection to the baseband network interface 320. In this manner, a subscriber or field technician can connect a laptop or desktop computer to the end-user device 204 and make use of the end-user device 204 as a gateway to the secondary communication path 239. The controller 310 makes use of the baseband network interface 320 to transmit return signals, such as a request for an IPPV movie. By way of example, the subscriber can instruct the end-user device 204, via a remote control, a push button control, or other user interface (not shown), to request the IPPV movie. In response to the subscriber instruction, the controller 310 creates and transmits a 21 request for the IPPV movie to the headend 202. The controller 310 converts the subscriber's instruction into a return signal containing the request for the IPPV movie. The controller 310 then forwards the return signal to the baseband network interface 320 which transmits the return signal over the connection 228 (Fig. 2) as data signals 332 to the baseband gateway 232 (Fig. 2). The controller 310 also receives data signals 332 from the baseband network interface 320. The received data signals 332 can include decryption information associated with the IPPV movie requested by the subscriber. The controller 310 can extract the decryption information from the data signals 332, allowing the controller 310 to decode the IPPV movie transmitted in the downstream signals 324. In this manner, the end-user device 204 is able to transmit return signals to and receive signals from the headend 202 without burdening the broadband network 224 (Fig. 2). There are several benefits of the exemplary end-user device 204 over existing devices. For instance, the exemplary end-user device 204 eliminates some of the components in use in set-top boxes and broadband networks today, such as a modulator/demodulator pair for return signals. The secondary communication path created by the exemplary embodiment eliminates the existing need for multiple subscribers to share the upstream or downstream bands of the broadband frequency spectrum for return signals. Moreover, the exemplary embodiment does not require additional electronics in the downstream direction to accumulate, parse out, and redirect return signals back to the headend 102, as is used in certain existing communications networks. Fig. 4 is a flow chart illustrating the steps performed by a communications network, for example, the communications network 200 illustrated in Fig. 2, having a secondary communication path for communicating between a service provider and an end-user device. For 22 the purposes of this discussion, there are two types of signals transmitted over the broadband network: downstream signals and return signals. The term "downstream signals" relates to signals, such as television programming, video content, decryption information, music programming or the like, which are transmitted from a service provider to a subscriber. The term "return signals" refers to signals, such as an electronic request to transmit an IPPV movie or the like, which are transmitted from the subscriber to the service provider. Turning now to the flow chart in Fig. 4, a method 400 proceeds from beginning step 401 to block 404. At block 404 the communications network transmits a first downstream signal containing multiple options, such as a listing of IPPV movies available to a subscriber for purchase. The first downstream signal is broadcast "out- of-band" over a secondary communication path to the end-user device. In this exemplary embodiment, the secondary communication path is a bi-directional communication path, separate from a primary communication path, between an end-user device and a service provider. For instance, the secondary communication path can be a data communications network, such as an Ethernet wide area network, between the end-user device and the service provider. The primary communication path may be a broadband network from the service provider to the end-user device. The method then proceeds to block 408. At block 408, one of the options in the first downstream signal is recognized at the end-user device as a selected option. For example, the subscriber can select an option using a remote control or the like. A selected option can be a particular IPPV movie, a particular music channel or the like. Once the selected option is recognized, at block 412, the end-user device generates a return signal. The return signal can be a request to view the particular IPPV movie or to listen to the particular music channel associated with the selected option. 23 At block 416, the return signal is transmitted from the end-user device to the service provider over the secondary communication path. As mentioned above, the secondary communication path is separate from the primary communication path. Accordingly, transmitting the return signal from the end-user device to the service provider does not consume bandwidth in the primary communication path. When received, the service provider acts upon the return signal in two ways, illustrated in the flow chart by a branched arrow. In one way, at block 422, the service provider generates a second downstream signal, such as the video content of the particular IPPV movie selected by the subscriber. Then at block 426, the service provider may transmit the second downstream signal to the end-user device over the primary communication path. Returning to block 430, concurrently with the steps at blocks 422 and 426, the service provider generates a third downstream signal, such as decryption information relating to the IPPV movie. At block 434, the service provider transmits the third downstream signal to the end-user device over the secondary communication path. By transmitting the third downstream signal over the secondary communication path, the bandwidth of the primary communication path is not reduced by the third downstream signal. At block 438, the end-user device uses the third downstream signal to prepare the second downstream signal to be presented to the subscriber. For instance, if the second downstream signal is an encoded IPPV movie, and the third downstream signal is decryption information related to the encoded IPPV movie, the end- user device can use the decryption information to decode and to present the encoded IPPV movie to the subscriber in the form of television programming. The method then ends at ending block 442. 24 It will be appreciated from the above that the present invention provides a "secondary communication path" for return signals in a communications network having a "primary communication path." The primary communication path extends from a headend to an end-user device at a subscriber location and delivers downstream signals to the end-user device. The secondary communication path is a bi-directional communication path between the end-user device at the subscriber location and the headend. The secondary communication path is capable of carrying return signals from the end-user device to the headend without consuming bandwidth in the primary communication path of the communications network. From a reading of the description above pertaining to the disclosed embodiment of the present invention, modifications and variations thereto may " become apparent to those skilled in the art. Therefore, the scope of the present invention is to be limited only by the following appended claims.

Claims: 25 CLAIMS What is claimed is: 1. In a communications network having a primary communication path for delivering a downstream signal from a headend to a subscriber location, a system for transmitting a return signal from the subscriber location to the headend without consuming bandwidth in the primary communication path, the system comprising: a secondary communication path, having an upstream direction and a downstream direction, the secondary communication path operative for transmitting the return signal from the subscriber location to the headend in the upstream direction; and an end-user device at the subscriber location, the end-user device having a first network interface connected to the primary communication path for receiving the downstream signal from the headend, the end-user device further having a second network interface connected to the secondary communication path for transmitting the return signal to the headend in the upstream direction, whereby the return signal is transmitted from the end-user device to the headend over the secondary communication path without consuming bandwidth in the primary communication path. 2. The communications network of Claim 1, wherein the downstream signal is modulated and frequency division multiplexed. 26 3. The communications network of Claim 1, wherein the secondary communication path comprises: a gateway connected to the headend and capable of bi-directional communications; and a network connected between the gateway and the second network interface of the end-user device, the network being operative to deliver the return signal from the end-user device to the gateway. 4. The communications network of Claim 3, wherein the network comprises a baseband network. 5. The communications network of Claim 1, wherein the end-user device comprises a demodulator for demodulating the downstream signal into a plurality of broadcast signals; and wherein the second network interface comprises a baseband network interface. 27 6. In a communications network having a primary communication path for delivering a downstream signal, an end-user device for transmitting a return signal to a headend, the end-user device comprising: a first network interface capable of receiving the downstream signal over the primary communication path, the downstream signal being frequency division multiplexed and modulated; and a second network interface capable of transmitting the return signal over a secondary communication path from the end-user device to the headend, the secondary communication path being a baseband communication path, whereby the return signal is transmitted from the end-user device to the headend over the secondary communication path, thereby avoiding the consumption of bandwidth in the primary communication path. 7. The end-user device of claim 6, wherein the first network interface comprises a demultiplexer and a demodulator for demultiplexing and demodulating the downstream signal. 8. The end-user device of claim 6, wherein the second network interface comprises a bi-directional communications interface. 9. The end-user device of claim 8, wherein the second network interface comprises a communications interface compatible with the ethernet communications network protocol. 28 10. The end-user device of claim 6, further comprising a controller operative to interpret the downstream signal received by the first network interface, and to generate the return signal for transmission by the second network interface to the headend. 29 11. A method of communicating between a headend and an end-user device at a subscriber location over a communications network, comprising the steps of: delivering a first downstream signal from the headend over a primary communication path to the end-user device at the subscriber location; generating a return signal at the end-user device based on the first downstream signal; transmitting the return signal from the end-user device over a secondary communication path from the end-user device to the headend; and delivering a second downstream signal from the headend over the primary communication path to the end-user device, the second downstream signal being related to the return signal, whereby the return signal is transmitted between the end- user device and the headend over the secondary communication path, thereby avoiding consumption of bandwidth in the primary communication path. 12. The method of claim 11, further comprising the step of: after delivering the second downstream signal, delivering a third downstream signal related to the second downstream signal from the headend to the end-user device over the secondary communication path, whereby the delivery of the third downstream signal does not consume bandwidth in the primary communication path. 30 13. A method of ordering a service over a communications network, the communications network including a headend and a subscriber location, the subscriber location having an end-user device operative for receiving signals from the headend over the communications network, for receiving a user input, and for transmitting a return signal to the headend, comprising the steps of: transmitting a first downstream signal to the end-user device over a secondary communication path between the headend and the end-user device, the first downstream signal including a set of options; recognizing the user input at the end-user device indicating a selected option from the set of options; generating the return signal at the end-user device relating to the selected option; formatting the return signal for transmission over the secondary communication path between the end-user device and the headend; transmitting the return signal from the end-user device to the headend over the secondary communication path; and in response to receipt of the return signal by the headend, delivering a second downstream signal to the end-user device over a primary communication path, the second downstream signal being related to the selected option. 14. The method of claim 13, further comprising: also in response to the receipt of the return signal by the headend, delivering a third downstream signal from the headend to the end-user device over the secondary communication path, the third downstream signal being related to the second downstream signal. 31 15. A communications network, comprising: a headend for generating a downstream signal for distribution to a subscriber location in the communications network; a first gateway for connecting the headend to a broadband network, the broadband network operative for distributing the downstream signal to the subscriber location; an end-user device at the subscriber location having a first network interface connected to the broadband network for receiving the downstream signal, the end-user device operative for converting the downstream signal to a format which can be displayed, the end-user device having a bi-directional second network interface capable of transmitting a return signal; a second gateway connected to the second network interface of the end-user device and capable of bi-directional communications, the second gateway being operative for receiving the return signal from the end-user device; and a baseband network connected between the second gateway and the headend for delivering the return signal from the second gateway to the headend. 16. The communications network of claim 15, wherein the first gateway comprises a broadband gateway capable of modulating and frequency division multiplexing the downstream signal. 17. The communications network of claim 15, wherein the second gateway comprises a baseband gateway capable of transmitting the return signal at baseband. 32 18. The communications network of claim 15, wherein the first gateway comprises a broadband gateway capable of modulating and frequency division multiplexing the downstream signal, and wherein the second gateway comprises a baseband gateway capable of transmitting the return signal at baseband. 19. The communications network of claim 15, wherein the broadband network comprises a um-directional distribution medium, and wherein the baseband network comprises a bi-directional distribution medium. 20. The communications network of claim 15, wherein the downstream signal comprises video content.

Inventors: ESTES DANIEL L, ESTES, DANIEL, L.
Applicants: BELLSOUTH INTELLECT PTY CORP, BELLSOUTH INTELLECTUAL PROPERTY CORPORATION
Application year: 1999
Main classification: H04N7
IPC codes: H04N7