WO2007046877A2

WO2007046877A2 - Cable remodulator

Info

Publication number: WO2007046877A2
Application number: PCT/US2006/021096
Authority: WO
Inventors: Paul Gothard Knutson; Max Ward Muterspaugh; Kumar Ramaswamy
Original assignee: Thomson Licensing SAS
Current assignee: Thomson Licensing SAS
Priority date: 2005-10-12
Filing date: 2006-05-31
Publication date: 2007-04-26
Anticipated expiration: 2008-04-12
Also published as: WO2007046877A3

Abstract

An apparatus for use in a cable system comprises a first port for use in coupling to a portion of a cable network for receiving an upstream signal having a frequency spectrum including a first frequency band; and a remodulator for translating the first frequency band of the received upstream signal to a second frequency band for transmission back downstream via the first port; wherein the first frequency band and the second frequency band are different from those frequency bands used by a head-end of the cable network for Internet communications.

Description

CABLE REMODULATOR

BACKGROUND OF THE INVENTION

[0001] The present invention generally relates to communications systems and, more particularly, to cable television systems. [0002] Current cable television (TV) systems offer a number of services to customers such as TV programming (both network and local), pay-per-view programming and Internet access. One example of a cable TV system is a hybrid fiber/coax based network that has a bandwidth capacity of 750 MHz (millions of hertz), or more, for delivering these services to their subscribers. This bandwidth capacity is typically divided between a down stream channel and an upstream channel. The downstream channel conveys not only the TV programming but also the downstream Internet data communications to each subscriber; while the upstream channel conveys the upstream Internet data communications from each subscriber.

SUMMARY OF THE INVENTION [0003] The above described distribution of cable TV bandwidth into a downstream channel and an upstream channel does not efficiently support peer-to-peer communications since any data communicated between endpoints must pass through the cable head-end. Therefore, and in accordance with the principles of the invention, an apparatus for use in a network comprises a first port for use in coupling to a portion of a network for receiving an upstream signal having a frequency spectrum including a first frequency band; and a remodulator for translating the first frequency band of the received upstream signal to a second frequency band for transmission back downstream via the first port; wherein the first frequency band and the second frequency band are different from those frequency bands used by a controller of the network for bi-directional communications. [0004] In an illustrative embodiment of the invention, a device for use in a network is a remodulator. Illustratively, the network is a cable network and the controller is a head-end of the cable network. The remodulator comprises a first mixer for mixing a received upstream signal at a first frequency to provide an intermediate frequency signal; a intermediate frequency filter for filtering the intermediate frequency signal to provide a filtered signal; and a second mixer for mixing the filtered signal at a second frequency to provide an output signal for downstream transmission, wherein a frequency spectrum of the output signal includes a second frequency band and wherein the first frequency band and the second frequency band are different from those frequency bands used by a head-end of the cable network for bidirectional communications (e.g., Internet communications).

[0005] In another illustrative embodiment of the invention, a device for use in a network is a remodulator that comprises a demodulator for demodulating a received upstream signal for providing a demodulated upstream signal; and a modulator for modulating the demodulated upstream signal for providing a downstream signal for transmission back downstream, wherein a frequency spectrum of the downstream signal includes a second frequency band different from those frequency bands used by a controller of the network for bi-directional communications. [0006] In another illustrative embodiment of the invention, a device for use in a network is a cable modem comprising a port for use in coupling to a cable system; and at least one modem coupled to the port for (a) communicating to the internet over a first pair of frequency bands and (b) communicating to at least one other endpoint of the cable system over a second pair of frequency bands different from the first pair. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 shows an illustrative cable system in accordance with the principles of the invention;

[0008] FIG. 2 shows an illustrative frequency spectrum in accordance with the principles of the invention; [0009] FIG. 3 shows an illustrative embodiment of a remodulator device in accordance with the principles of the invention;

[0010] FIG. 4 shows another illustrative cable system in accordance with the principles of the invention;

[0011] FIG. 5 shows another illustrative embodiment of a remodulator device in accordance with the principles of the invention;

[0012] FIG. 6 shows another illustrative cable system in accordance with the principles of the invention;

[0013] FIG. 7 shows another illustrative embodiment of a remodulator device in accordance with the principles of the invention; [0014] FIG. 8 illustrates peer-to-peer communications in accordance with the principles of the invention; [0015] FIG. 9 shows another illustrative embodiment of a remodulator device in accordance with the principles of the invention; and

[0016] FIG. 10 shows an illustrative embodiment of a cable modem in accordance with the principles of the invention. DETAILED DESCRIPTION

[0017] Other than the inventive concept, the elements shown in the figures are well known and will not be described in detail. Also, familiarity with television broadcasting and receivers in the context of terrestrial, satellite and cable is assumed and is not described in detail herein. For example, other than the inventive concept, familiarity with current and proposed recommendations for TV standards such as NTSC (National Television Systems Committee), PAL (Phase Alternation Lines), SECAM (SEquential Couleur Avec Memoire) ATSC (Advanced Television Systems Committee) (ATSC) and ITU-T J.83 "Digital multi- programme systems for television, sound and data services for cable distribution" is assumed. Likewise, other than the inventive concept, familiarity with satellite transponders, cable head- ends, set-top boxes, downlink signals and transmission concepts such as eight-level vestigial sideband (8-VSB), Quadrature Amplitude Modulation (QAM), out-of-band control channels and receiver components such as a radio-frequency (RF) front-end, or receiver section, such as a low noise block, tuners, and demodulators is assumed. Similarly, formatting and encoding methods (such as Moving Picture Expert Group (MPEG)-2 Systems Standard (ISO/IEC 13818-1)) for generating transport bit streams are well-known and not described herein. It should also be noted that the inventive concept may be implemented using conventional programming techniques, which, as such, will not be described herein. Finally, like-numbers on the figures represent similar elements. Also, as used herein, the term "endpoint" includes, but is not limited to, stations, personal computers, servers, set-top boxes, cable modems, etc.

[0018] Turning now to FIG. 1, an illustrative cable system 100 in accordance with the principles of the invention is shown. Illustratively, cable system 100 is a hybrid-fiber coax (HFC) system. For simplicity, the fiber portion is not described herein. It should be noted that although the inventive concept is described in the context of coaxial cable (coax), the inventive concept is not so limited and can be extended to the processing of fiber optic signals. A plurality of stations, as represented by stations 120-1 to 120-6, are connected to a common head-end 105 by a tree and branch cable network. . In the context of the inventive concept, a head-end is an example of a controller for a network. Each station is associated with a cable subscriber. Each station includes, e.g., a set top box for receiving video programming and a cable modem for bi-directional data communications to a two-way network, e.g., the Internet. Head-end 105 is a stored-program-processor based system and includes at least one processor (e.g., a microprocessor) with associated memory, along with a transmitter and receiver coupled to the cable network (for simplicity, theses elements are not shown). Ignoring for the moment element 200, the cable network comprises a main coaxial cable 106 having a plurality of taps 110-1, 110-2 to HO-N. Each of these taps serves a corresponding feeder cable. For example, tap 110-1 serves feeder cable 111-1. Each feeder cable in turn serves one, or more, stations via a tap and a drop. For example, feeder cable 111-1 serves station 120-1 via tap 115-1 and drop 116-1. For the purposes of this description, it is assumed that the devices of cable network 100, e.g., taps, drops, etc., are addressable and controllable by head-end 105 via an out-of-band signaling channel (not shown, in FIG. 1). Other than the inventive concept, the. use of an out-of-band signaling channel to address and control devices in particular portions of the cable network is known. For example, an out-of- band control channel that is a frequency shift keying (FSK) based can be used for both addressing and control of devices in a cable network. One such system is the Addressable Multi-Tap Control System available from Blonder Tongue Laboratories, Inc. [0019] In cable system 100, communications between head-end 105 and the various stations occurs in both an upstream direction and a downstream direction. The upstream direction is towards head-end 105 as represented by the direction of arrow 101 and the downstream direction is towards the stations as represented by the direction of arrow 102. In accordance with the principles of the invention, cable system 100 includes a device that enables peer-to-peer communications between endpoints of cable system 100 without having to pass through the head-end 105. This is further illustrated in FIG. 1 by remodulator (remod) device 200, which is illustratively located at the beginning of feeder cable 111-1. However, the inventive concept is not so limited and a device including the remodulator function can be located in any portion of the cable network. Turning for the moment to FIG. 2, in accordance with . the principles of the invention a number of pairs of upstream, and downstream communication bands are added to the existing cable frequency spectrum. Typically, a cable system provides services via an upstream band 11 and a downstream band 12. These services include Internet communications and television programming. However, in order to enable peer-to-peer communications, additional pairs of upstream and downstream bands are now added. These pairs of peer-to-peer frequency bands are different from those used by the cable system for Internet communications. Illustratively, FIG. 2 illustrates three pairs of peer-to- peer bands located between upstream band 11 and downstream band 12. However, the inventive concept is not so limited and more, or less, bands may be used and their placement in the spectrum may vary. It should also be noted that FIG. 2 is not to scale and that transition regions between bands may be required. As shown in FIG. 2, the three pairs of peer-to-peer bands are: BO, Bl and B2. The pair BCTcomprises an upstream band, BOu (51) and a downstream band, BOd (54); the pair Bl comprises an upstream band, BIu (52) and a downstream band, Bid (55); and the pair B2 comprises an upstream' band, B2u (53) and a downstream band, B2d (56).

[0020] Returning to FIG.. 1, remod device 200 receives a communication from an endpoint located off of feeder cable 111-1 (e.g., station 120-1) via an upstream peer-to-peer band as represented by dashed arrow 31 (e.g., BOu of FIG. 2). Remod device 200 translates the frequency of this received signal and changes its direction to transmit that communication downstream to other users located off of feeder cable 111-1 via a downstream peer-to-peer band as represented by dashed arrow 32 (e.g., BOd of FIG. 2).

[0021] Turning now to FIG. 3, an illustrative embodiment of remod device 200 is shown. Remod device 200 comprises directional coupler 205, input filter 215, mixer (multiplier) 225, 1st local oscillator 220, intermediate frequency (IF) filter 230, mixer (multiplier) 235, 2nd local oscillator 240, output filter 245 and amplifier 250. An upstream signal from drop 201 is received via directional coupler 205, which is provided to input filter 215. Input filter 215 has one, or more, pass bands that correspond to the upstream peer-to-peer bands shown in FIG. 2. In other words, input filter 215 blocks signals outside of these frequency ranges (such as any frequency components of upstream band 11 and downstream band 12). The output signal 216, along with a sinusoidal signal 221 from 1st local oscillator 220, is applied to multiplier 225. The later frequency shifts output signal 216 as a function of the frequency of sinusoidal signal 221 to provide a frequency-shifted signal 226 to IF filter 230. The resulting IF filtered signal, along with a sinusoidal signal 241 from 2nd local oscillator 240, is applied to multiplier 235. The later further frequency shifts the IF filtered signal as a function of the frequency of sinusoidal signal 241 to provide a frequency-shifted signal 236 to output filter 245. The resulting frequency spectrum of frequency shifted signal 236 includes a corresponding one of the downstream peer-to-peer bands. In this regard, output filter 245 has a pass band that further isolates the downstream peer-to-peer band to provide output signal 246, which is amplified by amplifier 250 to provide downstream signal 251. The latter is coupled back to drop 201, via directional coupler 205, for transmission back downstream for receipt by, e.g., station 120-2. It should be noted that remod device 200 may be configurable to translate a particular one, or more, of the peer-to-peer bands of the cable network. For example, remod device 200 may be configured to only use peer-to-peer band BO of FIG. 2. This configuration is preferably performed via the above-mentioned out-of-band control channel (not shown in FIG. 3).

[0022] As can be observed from FIG. 3, two frequency conversions are used to translate the frequency of an upstream peer-to-peer band to a downstream peer-to-peer band. As such, actual values of the 1st local oscillator, 2nd local oscillator, and the specifications for the pass bands of input filter 215, IF filter 230 and output filter 245 depend on the actual frequency values for the pairs of peer-to-peer bands. It should be noted that two frequency conversions are used to provide agility and enable use of a fixed, highly selective, surface acoustic wave (SAW) intermediate frequency (IF) filter. However, the inventive concept is not so limited and a single frequency conversion may be performed but it should be noted that the resulting filter design may be more difficult. Also, amplifier 250 is provided if necessary to correct the gain due to losses in the filters and conversions, and to match the transmitted signal to the amplitude of the other channels in the cable system. It should be noted that although FIG. 3 shows as amplifier 250 a single component, this amplifier may be distributed in the other elements of the remodulator for circuit optimization.

[0023] As noted above, a cable system may have one, or more, devices supporting a remodulator function located in one, or more, portions of the cable network. Illustratively, FIG. 1 shows a remod device coupled to a feeder cable. Another illustrative location and type of remod device is shown in FIG. 4. The elements in FIG. 4 are similar to those found in FIG. 1 except for remod device 300, which serves feeder cable 111-1. As can be observed, all upstream and downstream communications pass through remod device 300. An illustrative embodiment of remod device 300 is shown in FIG. 5.

[0024] Remod device 300 comprises switches 315, 320 and 325, up/down band stop (BS) filter 310, network control interface 305, splitter 330 and remod device 200. The latter is identical to remod device 200 of FIG. 3, except that directional coupler 205 of FIG. 3 is coupled to path 204 as shown in FIG. 5. Network control interface 305 allows a system control processor (not shown) in the cable network (e.g., located in head-end 105) the ability to configure the remodulator, e.g., whether it is on or off, establish frequency (e.g., which peer-to-peer bands to use) and/or gain settings. Illustratively, in this embodiment, network control interface 305 controls whether or not the remodulator function is enabled for feeder cable 111-1. In particular, network control interface 305 is responsive to the above-mentioned out-of-band signaling channel (represented by signal 304) for enabling or disabling the remodulator function in remod device 300 via switches 315, 320 and 325, which are controlled by network control interface 305 via control signal 306 (shown in dotted-line form). In this regard, the out-of-band signaling channel is modified to include predefined commands that are associated with enabling or disabling the remodulator function in a particular device. When the remodulator function is disabled, switches 315 and 310 are configured such that all upstream signals received, via path 331, from feeder. cable 1 11-1 are passed, via splitter 330, to main coaxial cable 106. Likewise, all downstream signals received, via path 316, from the main coaxial cable 106 are passed, via splitter 330, to feeder cable 111-1. In addition, switch 315 disconnects remod device. 200 from the network. However, when the remodulator function is enabled, all upstream signals received, via path 331, from feeder cable 111-1 are also provided to remod device 200, via switch 325. Remod device 200 functions as described above to translate one, or more, upstream peer-to-peer bands to a corresponding downstream peer-to-peer band for transmission back down feeder cable 111-1. Further, when the remodulator is enabled, up/down BS filter 310 is now switched in to further filter both upstream and downstream communications. BS filter 310 has stop bands that correspond to the peer-to-peer bands used by remodulator device 200 and any other remodulator devices located further downstream of path 331. For example, if remod device 200 is configured to only use peer-to-peer band BO of FIG. 2, up/down BS filter 310 has a stop band corresponding to peer-to-peer band BO to prevent any interference with the peer-to-peer transmission using band BO on feeder cable 111-1. [0025] Another illustrative embodiment of a cable system in accordance with the principles of the invention is shown in FIG. 6. This figure is similar to FIG. 5 except for tap 400, which includes the remodulator function. Tap 400 is shown in^'more detail in FIG. 7. As can be observed from FIG. 7, tap 400 comprises remod device 300 (described above). Thus, and in accordance with the principles of the invention, tap 400 is used to provide a remodulator function in the cable system.

[0026] As described above, the remodulator function is deployed in the cable network to provide local area peer-to-peer connectivity. FIG. 8 shows an illustrative application of the inventive concept to a cable network in the context of a number of remod devices. As indicated earlier, one, or more, of these remod devices may actually be incorporated in other devices of the cables network, such as taps, etc. In this example, it is assumed that there are three peer-to-peer bands as shown in FIG. 2. Each of the peer-to-peer bands is associated with a particular portion of the cable network. In this example, the cable network is mapped to a communication hierarchy having a number of levels. The top level is represented by remod device 405; the next level is represented by remod devices 410, 415 and 420; and the last level is represented by remod devices 425, 430 435, 440, 445, 450, 455, 460 and 465. Each level is indicative of a relative placement in the cable network and is also representative of a level of connectivity. In FIG. 8, the upstream direction is indicated by arrow 401. As such, the top level (remod device 405) is located further upstream (closer to the cable headend). An illustrative location for remod device 405 is near the optical/electronic (O/E) interface of the cable network. The next level (remod devices 410, 415 and 420) are located further downstream, e.g., in each of the taps that serve a particular feeder cable (or branch) of the cable network. The last level (remod devices 425 through 465) are located even further downstream, e.g., in each of the taps that serve a particular drop of the cable network. The top level uses peer-to-peer band BO; the next level uses peer-to-peer band B 1 and the last level uses peer-to-peer band B2. It is assumed for the purposes of this example that each remod device blocks upstream transmission of its assigned peer-to-peer band (using, e.g., a band stop filter as illustrated by BS filter 310 of FIG. 5) but passes communications in any of the other peer-to-peer bands in either direction.

[0027] Thus, and in accordance with the principles of the invention, a User 0 located on a cable drop served by remod device 425 can communicate to similarly situated users - User 1 and User 2 - by using peer-to-peer band B2. Similarly, if User 0 desires to communicate with User 6, User 0 can use peer-to-peer band Bl. Finally, if User 0 desires to communicate with User 17, User 0 can use peer-to-peer band BO. It can be observed from FIG. 8 that the layer supported by peer-to-peer band 2 is reused 9 times, allowing local servers or caches to provide data to local users 9 times more efficiently than communication direct from the head-end. Similarly, peer-to-peer band Bl on the next higher 1 layer is reused 3 times; while peer-to- peer band BO is used only once. As noted earlier, one, or more, of these remod devices can be configured and enabled/disabled via the out-of-band control channel.

[0028] As described above, the inventive concept allows for the deployment of peer-to- peer network operations in a cable plant. Illustratively, the cable plant reserves bands for local uplink and downlink use and one, or more, devices with a remodulator function are placed in the network. This allows a signal source at the edge of the network to transmit a signal upstream to the remodulator. The remodulator changes the direction and translates the frequency of the signal so that downstream users can receive the signal. As noted above, this device may be deployed at any portion of the cable network. It should be noted that installation further upstream may enable larger peer-to-peer coverage areas, but may require changes to the amplifiers of the cable network.

[0029] Another illustrative embodiment of a device having a remodulator function is shown in FIG. 9. Remod device 600 comprises directional coupler 205, upstream demodulator 605, decoder 610, coder 615 and downstream modulator 620. Remod device 600 is coupled to a cable network via path 204. An upstream signal from the cable network is received via directional coupler 205, which is provided to upstream demodulator 605. The latter is tuned to the appropriate peer-to-peer band. This can be accomplished via the earlier mentioned out-of-band control channel (not shown in FIG. 9). Upstream demodulator 605 demodulates the received upstream signal in the designated peer-to-peer band (e.g., BOu) and provides a demodulated signal to decoder 610, which decodes the signal to provide a decoded signal to coder 615. The later re-encodes the data to provide a coded signal to downstream modulator 620, which modulates the coded signal for transmission downstream in the corresponding peer-to-peer band (e.g., BOd). While this illustrative embodiment may be more complex than the approaches shown, e.g., in FIG. 3, the approach shown in FIG. 9 may provide a better downstream signal (equalization and error correction are performed after only one trip of one direction through the cable) and also allows for changes to the format of the modulated signals. Finally, as shown in FIG. 5, this embodiment may also be configured to have a band stop filter, switches, etc. It should be noted that the separate decoder and coder functions of FIG. 9 may be included in the demodulator and modulator, respectively. [0030] As described above, separate bands are used to provide peer-to-peer connectivity in a cable network. In this. regard, and in accordance with the principles of the invention, the cable modem function, or device, located in a station is modified to permit peer-to-peer communication. An illustrative embodiment of such a cable modem is shown in FIG. 10. Cable modem 700 comprises a peer-to-peer (P2P) modulator 705, a P2P demodulator 710, a downstream demodulator 715 and an upstream demodulator 720. Cable modem 700 is coupled to a cable network via a drop 701, a splitter 85 and path 704. The splitter 85 also provides a cable signal 702 to other equipment located at the station, e.g., a set top box (not shown). Upstream modulator 720 and downstream modulator 715 function as known in the art and enable a user to have Internet service and run. Internet applications (e.g., a browser located on a personal computer (PC) (not shown). P2P modulator 705 and P2P demodulator 710 provide the above-mentioned peer-to-peer connectivity and are configurable to one, or more, of the peer-to-peer bands (e.g., as illustrated in FIG. 2). These settings may be determined via software as options set by the user via the PC coupled to cable modem 700. In addition, the PC may store address information for particular members of the peer-to-peer network, where each address is associated with a particular peer-to-peer band. Upstream peer-to-peer communications is provided via signal 706 to P2P modulator 705, which provides an upstream signal in the designated peer-to-peer band. Downstream peer-to-peer communications is provided via signal 711 from P2P demodulator 710, which demodulates received signal in the designated peer-to-peer band. As described herein, peer-to-peer communications includes not only messaging, but also, e.g., broadcast messages, multicasting, etc. For example, a user can stream content from one endpoint to one or more other endpoints of the cable system in accordance with the principles of the invention. This content can be video, audio, etc. Further, although the inventive concept was described in the context of application to a traditional cable system, the inventive concept is not so limited and is applicable to any form of network, even, e.g., a home network, campus network, etc. [0031] As such, the foregoing merely illustrates the principles of the invention and it will thus be appreciated that those skilled in the art will be able to devise numerous alternative arrangements which, although not explicitly described herein, embody the principles of the invention and are within its spirit and scope. For example, although illustrated in the context of separate functional elements, these functional elements may be embodied in one or more integrated circuits (ICs). Similarly, although shown as separate elements, any or all of the elements may be implemented in a stored-program-controlled processor, e.g., a digital signal processor (DSP) or. microprocessor that executes associated software. For example, the separate modulator and demodulator functions shown in FIG. 10 may be located in one, or more, DSPs. The remodulator function can also be implemented in the digital domain by converting the incoming upstream signal to digital, and shifting the frequency in the digital domain, and outputting the remodulated downstream signal from a digital to analog converter and filter. ^' Further, although shown in particular configurations, the elements therein may be distributed in different units in any combination thereof. For example, a cable modem may be a part of a personal computer, a remodulator may be located in a server of the cable network, etc. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims.

Claims

1. Apparatus for use in a network, the apparatus comprising: a first port for use in coupling to a portion of a network for receiving an upstream signal having a frequency spectrum including a first frequency band; and a remodulator for translating the first frequency band of the received upstream signal to a second frequency band for transmission back downstream via the first port; wherein the first frequency band and the second frequency band are different from those frequency bands used by a controller of the network for bi-directional communications.

2. The apparatus of claim 1, wherein the network is a cable network and the controller is a head-end of the cable network.

3. The apparatus of claim 1, wherein the remodulator comprises: a first mixer for mixing the received upstream signal at a first frequency to provide an intermediate frequency signal; a intermediate frequency filter for filtering the intermediate frequency signal to provide a filtered signal; and a second mixer for mixing the filtered signal at a second frequency to provide an output signal for downstream transmission, wherein a frequency spectrum of the output signal includes the second frequency band.

4. The apparatus of claim 3, further comprising: an input filter for filtering the received upstream signal before application to the first mixer; an output filter for filtering the output signal for providing a filtered output signal; and an amplifier for amplifying the filtered output signal for transmission downstream.

5. The apparatus of claim 1, wherein the remodulator comprises: a demodulator for demodulating the received upstream signal for providing a demodulated upstream signal; and a modulator for modulating the demodulated upstream signal for providing a downstream signal for transmission back downstream, wherein a frequency spectrum of the downstream signal includes the second frequency band.

6. The apparatus of claim 5, further comprising: a decoder for use in providing the demodulated upstream signal; and a coder for use in coding the demodulated upstream signal before modulation by the modulator.

7. The apparatus of claim 1, wherein the apparatus is a part of a tap for use in the network.

8. The apparatus of claim 7, further comprising: a band stop filter coupled to the first port for filtering out those frequencies of the received upstream signal corresponding to the first frequency band for providing a filtered upstream signal; and a second port for use in coupling the filtered upstream signal to the network for transmission upstream.

9. The apparatus of claim 8 wherein the frequencies of the band stop filter are adjustable.

10. The apparatus of claim 1, further comprising: a network control interface responsive to a control signal for enabling or disabling the remodulator.

11. The apparatus of claim 10, wherein the control signal is an out-of-band control signal.

12. A cable modem comprising: a port for use in coupling to a cable system; and at least one modem coupled to the port for (a) communicating to a two-way network over a first pair of frequency bands and (b) communicating to at least one other endpoint of the cable system over a second pair of frequency bands different from the first pair.

13. A method for use in a device, the method comprising: coupling to a portion of a network for receiving an upstream signal having a frequency spectrum including a first frequency band; and translating the first frequency band of the received upstream signal to a second frequency band for transmission back downstream; wherein the first frequency band and the second frequency band are different from those frequency bands used by a controller of the network for bi-directional communications.

14. The method of claim 13, wherein the network is a cable network and the controller is a head-end of the cable network.

15. The method of claim 13, wherein the translating step includes: mixing the received upstream signal at a first frequency to provide an intermediate frequency signal; filtering the intermediate frequency signal to provide a filtered signal; and mixing the filtered signal at a second frequency to provide an output signal for downstream transmission, wherein a frequency spectrum of the output signal includes the second frequency band.

16. The method of claim 15, further comprising: filtering the received upstream signal before performing the mixing step at the first frequency; filtering the output signal for providing a filtered output signal; and amplifying the filtered output signal for transmission downstream.

17. The method of claim 13, wherein the translating step comprises: demodulating the received upstream signal for providing a demodulated upstream signal; and modulating the demodulated upstream signal for providing a downstream signal for transmission back downstream, wherein a frequency spectrum of the downstream signal includes the second frequency band.

18. The method claim 17, wherein the demodulating step includes decoding the demodulated upstream signal for providing the demodulated upstream a signal; and the modulating step includes encoding the demodulated upstream signal for providing the downstream signal.

19. The method of claim 13, wherein the device is a part of a tap for use in the network.

20. The method of claim 13, further comprising: filtering out those frequencies of the received upstream signal corresponding to the first frequency band for providing a filtered upstream signal; and coupling the filtered upstream signal to the network for transmission upstream.

21. The method of claim 13, further comprising: receiving a control signal for enabling or disabling the device.

22. The method of claim 21, wherein the control signal is an out-of-band control signal.

23. A method for use in a cable modem, the method comprising: coupling to a cable system; communicating to a two-way network over a first pair of frequency bands; and communicating to at least one other endpoint of the cable system over a second pair of frequency bands different from the first pair.