Abstract:
Methods and apparatus that transmit ultra-wideband signals through twisted-pair wire media are provided. One method includes transmitting an ultra-wideband signal through the twisted-pair wire media at dissimilar time periods. Another method includes transmitting an ultra-wideband signal through the twisted-pair wire media at dissimilar radio frequencies. Yet another method includes transmitting an ultra-wideband signal through the twisted-pair wire media at dissimilar time periods and at dissimilar radio frequencies. This Abstract is provided for the sole purpose of complying with the Abstract requirement rules that allow a reader to quickly ascertain the subject matter of the disclosure contained herein. This Abstract is submitted with the explicit understanding that it will not be used to interpret or to limit the scope or the meaning of the claims.

Description:
[0001]     This application is a continuation of co-pending U.S. non-provisional application Ser. No. 10/746,766, filed Dec. 23, 2003, entitled “Ultra-Wideband Communication Through Twisted-Pair Wire Media,” which is a continuation-in-part of U.S. non-provisional application Ser. No. 10/177,313, filed Jun. 21, 2002, entitled “Ultra-Wideband Communication Through a Wired Media,” now abandoned. 
     
    
     FIELD OF THE INVENTION  
       [0002]     The present invention generally relates to ultra-wideband communications. More particularly, the invention concerns a method to transmit ultra-wideband signals through twisted-pair wire media.  
       BACKGROUND OF THE INVENTION  
       [0003]     The Information Age is upon us. Access to vast quantities of information through a variety of different communication systems are changing the way people work, entertain themselves, and communicate with each other. For example, as a result of increased telecommunications competition mapped out by Congress in the 1996 Telecommunications Reform Act, traditional cable television program providers have evolved into full-service providers of advanced video, voice and data services for homes and businesses. A number of competing cable companies now offer cable systems that deliver all of the just-described services via a single broadband network.  
         [0004]     These services have increased the need for bandwidth, which is the amount of data transmitted or received per unit time. More bandwidth has become increasingly important, as the size of data transmissions has continually grown. Applications such as in-home movies-on-demand and video teleconferencing demand high data transmission rates. Another example is interactive video in homes and offices.  
         [0005]     Other industries are also placing bandwidth demands on Internet service providers, and other data providers. For example, hospitals transmit images of X-rays and CAT scans to remotely located physicians. Such transmissions require significant bandwidth to transmit the large data files in a reasonable amount of time. These large data files, as well as the large data files that provide real-time home video are simply too large to be feasibly transmitted without an increase in system bandwidth. The need for more bandwidth is evidenced by user complaints of slow Internet access and dropped data links that are symptomatic of network overload.  
         [0006]     Internet service providers, cable television networks and other data providers generally employ conductive wires and cables to transmit and receive data. Conventional approaches to signal (i.e. data) transmission through a transmission medium, such as a wire or cable, is to modulate the signal though the medium at a frequency that lies within the bounds at which the medium can electrically conduct the signal. Because of this conventional approach, the bandwidth of a specific medium is limited to a spectrum within which the medium is able to electrically transmit the signal via modulation, which yields a current flow. As a result, many costly and complicated schemes have been developed to increase the bandwidth in conventional conductive wire and/or cable systems using sophisticated switching schemes or signal time-sharing arrangements. Each of these methods is rendered costly and complex in part because the data transmission systems adhere to the conventional acceptance that the bandwidth of a wire or cable is constrained by its conductive properties.  
         [0007]     Therefore, there exists a need for a method to increase the bandwidth of conventional wired networks.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides a method to transmit ultra-wideband (UWB) pulses, or signals through any type of twisted-pair wire media.  
         [0009]     One embodiment of the present invention employs a multi-band UWB system. In this embodiment, different radio frequency spectra are assigned to each of the of the two twisted-pair wire groups comprising a twisted-pair wire. Any “cross talk,” or signal coupling that may occur between each of the twisted-pair wire groups can thereby be identified by the presence of an UWB pulse, or signal at an inappropriate frequency. This cross talk can then be disregarded, or eliminated.  
         [0010]     In another embodiment of the present invention, a single-band UWB system, most, if not all of, the radio frequency spectrum capability of the twisted-pair wire media may be utilized. In this embodiment, UWB pulses, or signals may be transmitted at staggered time intervals.  
         [0011]     Other embodiments may combine the above embodiments, and transmit UWB pulses having specific radio frequency spectra at staggered time intervals.  
         [0012]     One feature of the present invention is that it increases the available bandwidth, or data transmission rate capability, of twisted-pair media by providing additional data transfer capability. In addition, UWB pulses may coexist with other forms of electromagnetic communications, which may, or may not be present on the twisted-pair media.  
         [0013]     These and other features and advantages of the present invention will be appreciated from review of the following detailed description of the invention, along with the accompanying figures in which like reference numerals refer to like parts throughout. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]      FIG. 1  is an illustration of different communication methods;  
         [0015]      FIG. 2  is an illustration of two ultra-wideband pulses;  
         [0016]      FIG. 3  is a schematic illustration of one embodiment of an ultra-wideband communication system employing a wired medium;  
         [0017]      FIG. 4  is a schematic illustration of a second embodiment of an ultra-wideband communication system employing a wired medium;  
         [0018]      FIG. 5  is an illustration of different ultra-wideband (UWB) pulses employed in a multi-band UWB system;  
         [0019]      FIG. 6  is an illustration the radio frequency bands occupied by the UWB pulses illustrated in  FIG. 5 ;  
         [0020]      FIG. 7  is an illustration of one method of time staggering UWB pulses having different center frequencies;  
         [0021]      FIG. 8  is a schematic illustration of an UWB transmitter and receiver constructed according to one embodiment of the present invention;  
         [0022]      FIG. 9  is a schematic illustration of an UWB receiver constructed according to one embodiment of the present invention;  
         [0023]      FIG. 10  is a schematic illustration of an UWB multi-band transmitter constructed according to one embodiment of the present invention; and  
         [0024]      FIG. 11  illustrates UWB signals consistent with embodiments of the present invention. 
     
    
       [0025]     It will be recognized that some or all of the Figures are schematic representations for purposes of illustration and do not necessarily depict the actual relative sizes or locations of the elements shown. The Figures are provided for the purpose of illustrating one or more embodiments of the invention with the explicit understanding that they will not be used to limit the scope or the meaning of the claims.  
       DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     In the following paragraphs, the present invention will be described in detail by way of example with reference to the attached drawings. Throughout this description, the preferred embodiment and examples shown should be considered as exemplars, rather than as limitations on the present invention. As used herein, the “present invention” refers to any one of the embodiments of the invention described herein, and any equivalents. Furthermore, reference to various feature(s) of the “present invention” throughout this document does not mean that all claimed embodiments or methods must include the referenced feature(s).  
         [0027]     Generally, a traditional cable television provider, a community antenna television provider, a community access television provider, a cable television provider, a hybrid fiber-coax television provider, an Internet service provider, or any other provider of television, audio, voice and/or Internet data receives broadcast signals at a central station, either from terrestrial cables, and/or from one or more antennas that receive signals from a communications satellite. The broadcast signals are then distributed, usually by coaxial and/or fiber optic cable, from the central station to nodes located in business or residential areas.  
         [0028]     For example, community access television provider (CATV) networks are currently deployed in several different topologies and configurations. The most common configurations found today are analog signals transmitted over coaxial cable and Hybrid Fiber-Coax Systems (HFCS) that employ both fiber optic and coaxial cables. The analog coax systems are typically characterized as pure analog systems. Pure analog CATV systems are characterized by their use of established NTSC/PAL (National Television Standards Committee/Phase Alternation Line) modulation onto a frequency carrier at 6 or 8 MHz intervals.  
         [0029]     HFCS is a combination analog—digital topology employing both coaxial (analog) and fiber optic (digital) media that typically supports digitally modulated/encoded television channels above channel 78. According to ANSI/EIA-542-1997, in the United States, the analog channels are modulated in 6 MHz allocations on channels 2 to 78 using frequencies from 55 to 547 MHz. When using HFCS, digital channels typically start at channel 79 and go as high as 136 and occupy a frequency range from 553 to 865 MHz. In some extended HFCS systems, channel assignments can go as high as channel 158 or 997 MHz. The current ANSI/EIA-542-1997 standard only defines and assigns channels to these limits. The actual wire/cable media itself is generally capable of transmitting frequencies up to 3 GHz.  
         [0030]     In both CATV and HFCS systems, typically the satellite downlink enters the cable company&#39;s head-end and the video, and/or other data streams are de-multiplexed out. Individual video data streams (either NTSC, MPEG, or any other suitable protocol) are extracted from the satellite downlink stream and routed to modulators specific for individual television channels. The outputs from each modulator are then combined into one broadband signal. From this point the combined channels are amplified and sent out, either by coaxial or fiber optic cable, to the customers.  
         [0031]     In a HFCS, before the combined broadband signal leaves the head-end the broadband signal is modulated onto a fiber optic cable for distribution into the field, such as residential neighborhoods, or business districts. Modulation of the broadband signal is typically accomplished in one of two ways. In the first method the entire broadband signal is sampled and digitized using a high speed Analog to Digital Converter (ADC). To perform reliable digital sampling, the data must be sampled at a rate at least twice the highest frequency component to meet Nyquist minimum sampling requirements. To provide a higher quality data stream, the signal should be sampled at 2.5 to 4 times the highest frequency, which entails sample rates of approximately 2 to 4 GHz. A parallel to serial converter then shifts the parallel output data of the ADC into a serial format. The serial data then drives a laser diode for transmission over the fiber optic cable. The second method is broadband block conversion where the entire spectrum of the broadband signal is modulated onto the fiber optic cable.  
         [0032]     Designated access nodes are located in neighborhoods, business districts and other areas. The access nodes contain a high speed Digital to Analog Converter (DAC) and a de-serializer. A fiber optic receiver detects the laser-modulated signal at the access node. A parallel to serial converter de-serializes the data and it is feed to the high speed DAC. The data then leaves the access node on standard 75 ohm, RG-6 or RG-8 or other suitable coax cable and is distributed to the customer&#39;s premises. Thus, at the access node, the broadband signal is extracted from the fiber optic cable and transferred to a coaxial cable that connects to individual homes, apartments, businesses, universities, and other customers. Support of multiple customers is generally accomplished by the use of distribution boxes in the field, for example, on telephone poles or at ground level. However, as the signal is continuously split at the distribution boxes, the received bandwidth is reduced and the quality of the signal is diminished, thereby diminishing the video, audio, and other data quality.  
         [0033]     The digital channels that generally reside on CATV channels 79 and higher are fundamentally different than the analog channels that generally reside on channels 2 through 78. The analog channels are comprised of modulated frequency carriers. The digital channels, which generally use the 6 MHz allocation system, are digitally modulated using Quadrature Amplitude Modulation (QAM). QAM is a method of combining two amplitude modulated signals into a single channel, thereby doubling the effective bandwidth. In a QAM signal, there are two carriers, each having the same frequency but differing in phase by 90 degrees. The two modulated carriers are combined for transmission, and separated after transmission. QAM  16  transmits 16 bits per signal, QAM  32 ,  64 , and  256  each transmit 32, 54 and 256 bits per signal, respectively. QAM was developed to support additional video streams encoded with MPEG video compression. Conventional CATV and HFCS networks may employ QAM levels up to QAM  64  to enable up to 8 independent, substantially simultaneous MPEG video streams to be transmitted.  
         [0034]     At the customer&#39;s location, the coaxial cable is connected to either a set-top box or directly to a television. The receiving device then de-multiplexes and de-modulates the video, audio, voice, Internet or other data. Although a television can directly receive the analog signal, a set-top box is generally required for reception of the digitally encoded channels residing on CATV channels 79 and higher.  
         [0035]     The above-described networks, and other networks and communication systems that employ wired media, such as twisted-pair or coaxial cable, suffer from performance limitations caused by signal interference, ambient noise, and spurious noise. In these conventional wired media systems, these limitations affect the available system bandwidth, distance, and carrying capacity of the system, because the noise floor and signal interference in the wired media rapidly overcome the signal transmitted. Therefore, noise within the wired media significantly limits the available bandwidth of any wired system or network.  
         [0036]     Generally, the conventional wisdom for overcoming this limitation is to boost the power (i.e., increase the voltage of the signal) at the transmitter to boost the voltage level of the signal relative to the noise at the receiver. Without boosting the power at the transmitter, the receiver is unable to separate the noise from the desired signal. Thus, the overall performance of wired media systems is still significantly limited by the accompanying noise that is inherent in wired media.  
         [0037]     Increasing the available bandwidth of an established wired media network, while coexisting with the conventional data signals transmitted through the network, represents an opportunity to leverage the existing wired media network infrastructure to enable the delivery of greater functionality. Several methods and techniques have been proposed, but they are generally computationally intense, hence costly.  
         [0038]     The present invention may be employed in any type of network that uses wired media, in whole, or in part. That is, a network may use both wired media, such as coaxial cable, and wireless devices, such as satellites. As defined herein, a network is a group of points or nodes connected by communication paths. The communication paths may be connected by wires, or they may be wirelessly connected. A network as defined herein can interconnect with other networks and contain subnetworks. A network as defined herein can be characterized in terms of a spatial distance, for example, such as a local area network (LAN), a metropolitan area network (MAN), and a wide area network (WAN), among others. A network as defined herein can also be characterized by the type of data transmission technology in use on it, for example, a TCP/IP network, and a Systems Network Architecture network, among others. A network as defined herein can also be characterized by whether it carries voice, data, or both kinds of signals. A network as defined herein can also be characterized by who can use the network, for example, a public switched telephone network (PSTN), other types of public networks, and a private network (such as within a single room or home), among others. A network as defined herein can also be characterized by the usual nature of its connections, for example, a dial-up network, a switched network, a dedicated network, and a nonswitched network, among others. A network as defined herein can also be characterized by the types of physical links that it employs, for example, optical fiber, coaxial cable, a mix of both, unshielded twisted pair, and shielded twisted pair, among others.  
         [0039]     The present invention employs a “carrier free” architecture which does not require the use of high frequency carrier generation hardware, carrier modulation hardware, stabilizers, frequency and phase discrimination hardware or other devices employed in conventional frequency domain communication systems. The present invention dramatically increases the bandwidth of conventional networks that employ wired media, but can be inexpensively deployed without extensive modification to the existing wired media network.  
         [0040]     The present invention provides increased bandwidth by injecting, or otherwise super-imposing an ultra-wideband (UWB) signal into the existing data signal and subsequently recovers the UWB signal at an end node, set-top box, subscriber gateway, or other suitable location. Ultra-wideband, or impulse radio, employs pulses of electromagnetic energy that are emitted at nanosecond or picosecond intervals (generally tens of picoseconds to a few nanoseconds in duration). For this reason, ultra-wideband is often called “impulse radio.” Because the excitation pulse is not a modulated waveform, UWB has also been termed “carrier-free” in that no apparent carrier frequency is evident in the radio frequency (RF) spectrum. That is, the UWB pulses are transmitted without modulation onto a sine wave carrier frequency, in contrast with conventional radio frequency technology. Ultra-wideband requires neither an assigned frequency nor a power amplifier.  
         [0041]     Conventional radio frequency technology employs continuous sine waves that are transmitted with data embedded in the modulation of the sine waves&#39; amplitude or frequency. For example, a conventional cellular phone must operate at a particular frequency band of a particular width in the total frequency spectrum. Specifically, in the United States, the Federal Communications Commission has allocated cellular phone communications in the 800 to 900 MHz band. Cellular phone operators use 25 MHz of the allocated band to transmit cellular phone signals, and another 25 MHz of the allocated band to receive cellular phone signals.  
         [0042]     Another example of a conventional radio frequency technology is illustrated in  FIG. 1 . 802.11a, a wireless local area network (LAN) protocol, transmits radio frequency signals at a 5 GHz center frequency, with a radio frequency spread of about 5 MHz.  
         [0043]     In contrast, a UWB pulse may have a 1.8 GHz center frequency, with a frequency spread of approximately 4 GHz, as shown in  FIG. 2 , which illustrates two typical UWB pulses.  FIG. 2  illustrates that the narrower the UWB pulse in time, the higher its center frequency and the broader the spread of its frequency spectrum. This is because frequency is inversely proportional to the time duration of the pulse. A 600 picosecond UWB pulse will have about a 1.8 GHz center frequency, with a frequency spread of approximately 4 GHz. And a 300 picosecond UWB pulse will have about a 3 GHz center frequency, with a frequency spread of approximately 8 GHz. Thus, UWB pulses generally do not operate within a specific frequency, as shown in  FIG. 1 . And because UWB pulses are spread across an extremely wide frequency range, UWB communication systems allow communications at very high data rates, such as 100 megabits per second or greater.  
         [0044]     Further details of UWB technology are disclosed in U.S. Pat. No. 3,728,632 (in the name of Gerald F. Ross, and titled: Transmission and Reception System for Generating and Receiving Base-Band Duration Pulse Signals without Distortion for Short Base-Band Pulse Communication System), which is referred to and incorporated herein in its entirety by this reference.  
         [0045]     Also, because the UWB pulse is spread across an extremely wide frequency range, the power sampled at a single, or specific frequency is very low. For example, a UWB one-watt signal of one nano-second duration spreads the one-watt over the entire frequency occupied by the pulse. At any single frequency, such as at the carrier frequency of a CATV provider, the UWB pulse power present is one nano-watt (for a frequency band of 1 GHz). This is well within the noise floor of any wired media system and therefore does not interfere with the demodulation and recovery of the original CATV signals. Generally, the multiplicity of UWB pulses are transmitted at relatively low power (when sampled at a single, or specific frequency), for example, at less than −30 power decibels to −60 power decibels, which minimizes interference with conventional radio frequencies. However, UWB pulses transmitted through most wired media will not interfere with wireless radio frequency transmissions. Therefore, the power (sampled at a single frequency) of UWB pulses transmitted though wired media may range from about +30 dB to about −90 dB.  
         [0046]     For example, a CATV system generally employs a coaxial cable that transmits analog data on a frequency carrier. Generally, amplitude modulation (AM) or QAM (discussed above) are used to transmit the analog data. Since data transmission employs either AM or QAM, UWB signals can coexist in this environment without interference. In AM, the data signal M(t) is multiplied with a cosine at the carrier frequency. The resultant signal y(t) can be represented by: 
 
 y ( t )= m ( t )Cos(ω c   t ) 
 
 In a QAM based system multiple carrier signals are transmitted at the same carrier frequency, but at different phases. This allows multiple data signals to be simultaneously carried. In the case of two carriers, an “in phase” and “quadrature” carriers can carry data signals Mc(t) and Ms(t). The resultant signal y(t) can be represented as: 
 
 y ( t )= Mc ( t )Cos(ω c   t )+ Ms ( t )Sin(ω c   t ) 
 
         [0047]     However, as discussed above, an UWB system transmits a narrow time domain pulse, and the signal power is generally evenly spread over the entire bandwidth occupied by the signal. At any instantaneous frequency, such as at the AM or QAM carrier frequency, the UWB pulse power present is one nano-watt (for a frequency band of 1 GHz). This is well within the noise floor of any wired media system and therefore does not interfere with the demodulation and recovery of the original AM or QAM data signals.  
         [0048]     Wired media communication systems suffer from performance limitations caused by signal interference, ambient noise, and spurious noise. These limitations affect the available bandwidth, distance, and carrying capacity of the wire media system. With wired communication systems, the noise floor and signal interference in the wired media rapidly overcome the transmitted carrier signal. This noise on the wired media is a significant limitation to the ability of the system to increase bandwidth. UWB technology makes use of the noise floor to transmit data, without interfering with the carrier signal. Moreover, UWB transmitted through a wired medium has distinct advantages over its use in a wireless environment. In a wired environment there are no concerns with intersymbol interference, and there are no concerns relating to multi-user interference.  
         [0049]     For example, CATV channels typically occupy 6 MHz in the US and 8 MHz in Europe. These channels are arranged in a re-occurring pattern beginning at approximately 50 MHz and dependent on the CATV system, extend upward to 550 MHz, 750 MHz, 870 MHz, 1 GHz and higher. The present invention is capable of injecting UWB pulses into the existing CATV infrastructure. These UWB signals do not interfere or degrade existing frequency domain signals. Additionally, the UWB signals can carry vast amounts of information with digital meaning in the time domain.  
         [0050]     The present invention provides an apparatus and method to enable any wired media network to augment their available bandwidth. Preferably, this additional bandwidth is obtained by introducing UWB signals into the existing data transmission chain prior to broadcast from the system operator&#39;s head-end. As shown in  FIGS. 3 and 4 , the head-end may include several components, such as the antenna farm  15 , the satellite receivers  20 , the channel modulator  25 , the combiner  30 , and the fiber optic transmitter/receiver  35 . Alternatively, UWB signals may be introduced into the wired media network at other locations, such as at the Internet router  90  or at the host digital terminal  80 , or at any other suitable location.  
         [0051]     In like fashion, cable system operators can receive more data from individual subscribers by introducing subscriber-generated data into existing upstream channels. The present invention provides UWB communication across fiber optic and coaxial cable, twisted pair wires, or any other type of conductive wire. A wired media network will be able to both transmit and receive digital information for the purposes of telephony, high-speed data, video distribution, video conferencing, wireless base operations and other similar purposes.  
         [0052]     Referring to  FIG. 3 , the wired ultra-wideband communication system  10  is configured to transmit ultra-wideband signals over an existing network or system that includes wired media. For example, the wired ultra-wideband (UWB) system  10  may transmit UWB signals over an existing community access television network (CATV), an optical network, a cable television network, a community antenna television network, a hybrid fiber-coax television network, an Internet service provider network, a PSTN network, a WAN, LAN, MAN, TCP/IP network, a college campus, town, city, or any other type of network as defined above, that employs wired media, in whole or in part.  
         [0053]     One embodiment of the wired UWB communication system  10  is illustrated in  FIG. 3 . An antenna farm  15  receives audio, video and data information from one or more satellites (not shown). Additional data may be received by terrestrial cables and wires, and by terrestrial wireless sources, such as a multichannel multipoint distribution service (MMDS). The data is then forwarded to the satellite receivers  20  that demodulate the data into separate audio, video and data streams. This information is forwarded to the channel modulators  25  that receive the program signals, such as CNN or MTV. The channel modulators  25  mix each signal with a radio frequency (RF) and assign a station number (such as 2 to 99) that each program will be received on by subscribers.  
         [0054]     The multiple RF signals are then forwarded to a combiner  30  that combines the multiple signals into a single output. That is, the combiner  30  receives the program signals from the channel modulators  25  and combines them onto a single coax cable and forwards the signal to the fiber optic transmitter/receiver  35 . The above-described arrangement and function of channel modulators  25  and combiners  30  may vary with each type of wired media network.  
         [0055]     Additional audio, video, or other data signals received from either the antenna farm  15  or from terrestrial sources such as fiber optic or coaxial cables can be routed from the satellite receiver  20  to the service provider ultra-wideband (UWB) device  40 . The service provider UWB device  40  converts the audio, video, or other data signals received from the satellite receiver  20  into a multiplicity of UWB electromagnetic pulses. The service provider ultra-wideband (UWB) device  40  may include several components, including a controller, digital signal processor, an analog coder/decoder, one or more devices for data access management, and associated cabling and electronics. The service provider ultra-wideband (UWB) device  40  may include some, or all of these components, other necessary components, or their equivalents. The controller may include error control, and data compression functions. The analog coder/decoder may include an analog to digital conversion function and vice versa. The data access management device or devices may include various interface functions for interfacing to wired media such as phone lines and coaxial cables.  
         [0056]     The digital signal processor in the service provider ultra-wideband (UWB) device  40  modulates the audio, video, or other data signals received from the satellite receiver  20  into a multiplicity of UWB electromagnetic pulses, and may also demodulate UWB pulses received from the subscriber. As defined herein, modulation is the specific technique used to encode the audio, video, or other data into a multiplicity of UWB pulses. For example, the digital signal processor may modulate the received audio, video, or other data signals into a multiplicity of UWB pulses that may have a duration that may range between about 0.1 nanoseconds to about 100 nanoseconds, and may be transmitted at relatively low power, for example, at less than −30 power decibels to −60 power decibels, as measured across the transmitted frequency.  
         [0057]     The UWB pulse duration and transmitted power may vary, depending on several factors. Different modulation techniques employ different UWB pulse timing, durations and power levels. The present invention envisions several different techniques and methods to transmit an UWB signal across a wired medium. One embodiment, may for example, use pulse position modulation that varies the timing of the transmission of the UWB pulses. One example of a pulse position modulation system may transmit approximately 10,000 pulses per second. This system may transmit groups of pulses 100 picoseconds early or 100 picoseconds late to signify a specific digital bit, such as a “0” or a “1”. In this fashion a large amount of data may be transmitted across a wired medium. Alternatively, the UWB signal may be transmitted in a fashion similar to that described in U.S. patent application entitled, “ENCODING AND DECODING ULTRA-WIDEBAND INFORMATION,” Ser. No. 09/802;590 (in the name of John H. Santhoff and Rodolfo T. Arrieta), which is referred to and incorporated herein in its entirety by this reference.  
         [0058]     An alternative modulation technique may use pulse amplitude modulation to transmit the UWB signal across a wired medium. Pulse amplitude modulation employs pulses of different amplitude to transmit data. Pulses of different amplitude may be assigned different digital representations of “0” or “1.” Other envisioned modulation techniques include On-Off Keying that encodes data bits as pulse (1) or no pulse (0), and Binary Phase-Shift Keying (BPSK), or bi-phase modulation. BPSK modulates the phase of the signal (0 degrees or 180 degrees), instead of modulating the position. Spectral Keying, which is neither a PPM nor PAM modulation technique may also be employed. It will be appreciated that other modulation techniques, currently existing or yet to be conceived, may also be employed.  
         [0059]     A preferred modulation technique will optimize signal coexistence and pulse reliability by controlling transmission power, pulse envelope shape and Pulse Recurrent Frequencies (PRF). Both pseudo-random and fixed PRFs may be used, with the knowledge that a fixed PRF may create a “carrier-like frequency,” which it and its higher order harmonics may interfere with the data carried in conventional RF carrier channels. However, with a pseudo-random PRF the difficulties encountered with a fixed PRF are usually avoided. One embodiment of a pseudo-random PRF modulation technique may include a UWB pulse envelope that is shaped to pre-amplify and compensate for high frequency components that the wired media may naturally attenuate. UWB pulse envelope shaping has the additional advantage of controlling the power spectral density of the transmitted data stream.  
         [0060]     Several advantages exist when transmitting UWB pulses through wired media as opposed to transmitting UWB pulses through a wireless medium. Wireless UWB transmissions must consider such issues as Inter-Symbol Interference (ISI) and Multi-User Interference (MUI), both of which can severely limit the bandwidth of UWB transmissions. Some modulation techniques such as Pulse Amplitude Modulation (PAM), which offer the ability for high bit densities are not effective at long wireless distances. These, and other issues, do not apply to UWB pulses transmitted over wired media. In addition, no multipath issues arise and there are no propagation delay problems present in a wired medium. Therefore, it is estimated that an ultra-wideband system may be able to transmit data across a wired medium in a range from 100 Mbit/second to 1 Gbit/second. This data rate will ensure that the bandwidth requirements of any service provider can be met.  
         [0061]     A preferred embodiment of the service-provider UWB device  40  will spread the signal energy of the UWB data stream across the a bandwidth that may ranger from 50 MHz to approximately 870 MHz or as discussed above, to 1 GHz, or higher. This will ensure that the signal energy present at any frequency is significantly below the normal noise floor for that frequency band, further ensuring coexistence with conventional RF carrier data.  
         [0062]     For example, a UWB pulse would have a duration of about 1 nano-second in a UWB data stream that has a 1 GHz bandwidth. Alternatively, the UWB pulse duration would be tailored to match the available frequency of the specific network. For a CATV or HFCS network located in the United States, an ideal UWB pulse would generally be about 0.5 to 2 nano-seconds in duration. This is because a conventional CATV or HFCS network located in the United States typically utilizes a maximum frequency of approximately 870 MHz, but has the capacity to utilize up to 1 GHz. This bandwidth allows for a 1 to 2 nano-second pulse duration. A narrow pulse width is preferred because more pulses can be transmitted in a discrete amount of time. Pulse widths of up to 2 nano-seconds may be employed to guarantee pulse integrity throughout digitization, transmission, reception and reformation at the UWB subscriber device  50 . Generally, an idealized pulse width would be calculated based on the frequency response of the specific wired media system.  
         [0063]     Referring to  FIG. 3 , the multiplicity of generated UWB pulses are sent from the service-provider UWB device  40  to the combiner  30 , which combines the UWB pulses with the conventional RF carrier signals. One method to accomplish this task is to couple a wire carrying the conventional RF carrier signals to a standard coaxial splitter. A second wire carrying the UWB pulses is also coupled to the standard coaxial splitter. The combined signals are forwarded to the fiber optic transmitter/receiver  35 . The fiber optic transmitter/receiver  35  converts both the multiplicity of UWB pulses and the conventional RF carrier signals received from the combiner  30  into a corresponding optical signal. The optical signal generator can be either a light-emitting diode, solid state laser diode, or other suitable device. The optical signal is then distributed on fiber optic cables to residential neighborhoods, business districts, universities, colleges or other locations for distribution to subscribers and customers. Other methods and techniques for combining a UWB pulse stream and a conventional RF carrier signal stream may also be employed. For example, the UWB pulse stream my be sent directly to the fiber optic transmitter/receiver  35 , which will then combine the two signals.  
         [0064]     Shown in  FIG. 3 , a fiber multiplexer node  45  may be located at any one of the locations described above. The optical signals are received by the multiplexer  45  and are converted back to the combined conventional RF carrier and UWB pulsed signals. The combined signals are forwarded to a subscriber UWB device  50 . The subscriber UWB device  50  can be considered a gateway or router that provides access to the combined signals.  
         [0065]     One embodiment of the subscriber UWB device  50  will demodulate the multiplicity of UWB electromagnetic pulses back into a conventional RF carrier signal. The subscriber UWB device  50  may include all, some or additional components found in the service provider UWB device  40 . In this manner, additional bandwidth will be available to the wired media network to provide the additional data and functionality demanded by the customer.  
         [0066]     An alternative embodiment of the present invention is illustrated in  FIG. 4 . A full service wired UWB communication system  70  is structured to allow for extremely high data rate transmission of video, telephone, internet and audio signals.  
         [0067]     The full service UWB system  70  receives audio, video and data information from an antenna farm  15  or from terrestrial sources such as fiber optic or coaxial cables. These signals are forwarded to the satellite receivers  20  as described above with reference to the wired UWB communication system  10 . In addition, signals from a public telephone network  75  are received by a host digital terminal  80 . The host digital terminal  80  modulates multiple voice signals into two-way upstream and downstream RF signals. The voice signals from the host digital terminal  80  are forwarded to the service provider UWB device  40 .  
         [0068]     An internet service provider  85  forwards internet data to the internet router  90 . The internet router  90  generates packets, such as TCP/IP packets, which are forwarded to the service provider UWB device  40 .  
         [0069]     The service provider UWB device  40  modulates the internet data, the telephony data and the data received from the satellite receivers  20  into a multiplicity of electromagnetic pulses, as described above, and forwards the pulses to the combiner  30 . The combiner combines the UWB pulses with the conventional RF carrier signals and forwards the combined signal to the fiber optic transmitter/receiver  35 . The signals are then converted into an optical signal by either a light emitting diode, solid state laser diode, or other suitable device. The optical signal is then distributed to the fiber multiplexer node  45  located within business districts, residential neighborhoods, universities, colleges and other areas.  
         [0070]     The fiber multiplexer node  45  receives the fiber optic signal and converts them back to the combined conventional RF carrier and UWB pulsed signals. The combined signals are forwarded to a subscriber UWB device  50 . The subscriber UWB device  50  can be considered a gateway or router that provides access to the combined signals. The subscriber UWB device  50  demodulates the multiplicity of UWB electromagnetic pulses into RF signals and forwards the RF signals to appropriate locations such as televisions, personal computers or telephones. Alternative embodiment subscriber UWB devices  50  may be located adjacent to televisions sets similar to a set-top box and used to transmit on-demand movies, internet access or pay-per-view programs. Yet another embodiment of the present invention may include a UWB device  50  that may be located within a television set, or computer. The UWB device  50  is constructed to convert and distribute data to computers, network servers, digital or subscription televisions, interactive media devices such as set-top boxes and telephone switching equipment.  
         [0071]     The subscriber UWB device  50  may also be configured to transmit UWB pulses wirelessly to provide audio, video, and other data content to personal computers, televisions, PDAs, telephones and other devices. For example, UWB device  50  may include the necessary components to transmit and receive UWB or conventional RF carrier signals to provide access to interfaces such as PCI, PCMCIA, USB, Ethernet, IEEE1394, or other interface standards.  
         [0072]     The present invention will also allow for data to be transmitted “upstream” toward the service provider. For example, a conventional CATV or HFCS network reserves frequencies below 50 MHz for upstream traffic. One embodiment of the present invention may include a band-pass filter with stop-bands above 1 GHz, and below 50 MHz to ensure attenuation of UWB pulses so as not to interfere with upstream traffic. These filters also serve the purpose of limiting potential inter-modulation distortion that could be introduced by the UWB pulses.  
         [0073]     Alternative embodiments of the present invention may transmits UWB pulses through traditional telephone wires. Depending upon the provider, whether they be a local or long distance carrier, an UWB transmitter/receiver can be located in a regional center, sectional center, primary center, toll center, end-office, or their equivalents.  
         [0074]     The present invention of transmitting ultra-wideband signals across a wired medium can employ any type of wired media. For example, the wired media can include optical fiber ribbon, fiber optic cable, single mode fiber optic cable, multi-mode fiber optic cable, plenum wire, PVC wire, and coaxial cable.  
         [0075]     In addition, the wired media can include twisted-pair wiring, whether shielded or unshielded. Twisted-pair wire may consist of “pairs” of color-coded wires. Common sizes of twisted-pair wire are 2 pair, 3 pair, 4 pair, 25 pair, 50 pair and 100 pair. Twisted-pair wire is commonly used for telephone and computer networks. It comes in ratings ranging from category 1 to category 7. Twisted-pair wiring also is available unshielded. That is, the wiring does not have a foil or other type of wrapping around the group of conductors within the jacket. This type of wiring is most commonly used for wiring for voice and data networks. The foregoing list of wired media is meant to be exemplary, and not exclusive.  
         [0076]     As described above, the present invention can provide additional bandwidth to enable the transmission of large amounts of data over an existing wired media network, whether the wired media network is a Internet service provider, cable television provider, or a computer network located in a business or university. The additional bandwidth can allow consumers to receive the high speed Internet access, interactive video and other features that they are demanding.  
         [0077]     Referring now to  FIGS. 5-10 , additional methods and apparatus employed to transmit and receive data through twisted-pair wire media are illustrated. As introduced above, twisted-pair wire media generally comprise two wires twisted together to form a helix. The “pairs” of wires may be bound or otherwise grouped together to form 2 pair, 3 pair, 4 pair, 25 pair, 50 pair and 100 pair wire media. It will be appreciated that other numbers of pair groups may be employed by the present invention. These grouped pairs of wires are formed into a single cable used, for example, to connect homes and businesses to a telephone company, or to an Internet service provider.  
         [0078]     One problem associated with communication through twisted-pair wire media is “cross talk,” which is the undesired transfer of signals between or among the wires. To reduce cross talk, or electromagnetic induction, the two wires comprising a twisted-pair group are twisted around each other. However, this may not completely eliminate cross talk. This type of cross talk, sometimes known as “inductive” cross talk, is created by electromagnetic fields from signals transmitted through the wires. Twisting the wires about each other reduces, but does not eliminate cross talk. Cross talk can be exacerbated by signal modulation methods, signal transmission timing and other factors.  
         [0079]     One feature of the present invention is that it reduces, or eliminates cross talk, while simultaneously increasing the bandwidth, or data transmission rate capability of a communication system employing twisted-pair wire media.  
         [0080]     As discussed above, the present invention employs ultra-wideband (UWB) communication technology, which comprises extremely short duration electromagnetic pulses. As shown in  FIG. 2 , as the duration of a UWB pulse decreases, the amount of radio frequency (RF) spectrum that it occupies increases. Thus, UWB communication systems can tailor the duration of the UWB pulses to occupy any desired amount of RF spectrum.  
         [0081]     For example, the duration of each UWB pulse may be tailored so that the entire available RF spectrum of a twisted-pair wire is employed. This is generally known as a “single-band” UWB system. In this embodiment of the present invention, the UWB pulses are generated with widths, or durations designed to occupy the entire available bandwidth, or radio frequency spectrum of the twisted-pair media. For example, in a twisted-pair wire that has a 50 MHz bandwidth, each UWB pulse may have a duration of about 20 nano-seconds.  
         [0082]     Alternatively, the duration of each UWB pulse may be tailored so that only part of the available RF spectrum of the twisted-pair cable is occupied. This embodiment employs a “multi-band” UWB communication method. Referring to  FIGS. 5 and 6 , in one embodiment of the present invention, a “multi-band” UWB communication system is employed in the twisted-pair wire media. In a multi-band UWB system the available bandwidth, or RF spectrum, is segmented into a number of individual RF bands. UWB pulses can then be generated to fall within these RF bands. That is, once the available bandwidth is segmented into individual RF bands, UWB pulses are generated with the appropriate time duration to occupy the individual RF band.  
         [0083]     On feature of multi-band UWB systems is that they may be adaptive and scalable. For example, a multi-band UWB system may avoid transmission in a specific RF band where more sensitive narrowband, or conventional communications may be present. In RF bands where no narrowband communications are present, the UWB pulses may be transmitted at higher power enabling increased range, and other benefits.  
         [0084]     Referring to  FIG. 6 , a group of multi-band UWB pulses are illustrated. In this embodiment, the amount of bandwidth, or radio frequency spectrum occupied by UWB pulses  220 ( a ) through  220 ( j ) is essentially identical. The specific radio frequency occupied by each UWB pulse  220 ( a ) through  220 ( j ) is determined by the duration of each UWB pulse. This is illustrated in  FIG. 5 , where UWB pulses  110 ( a ) through  110 ( j ) correspond to frequency bands  220 ( a ) through  220 ( j ), illustrated in  FIG. 6 .  
         [0085]     In the twisted-pair wire media UWB communication system employing the multi-band method shown in  FIGS. 5-6 , the frequency bands are exclusive of each other. It will be appreciated that in other embodiment multi-band systems, these radio frequency assignments may overlap (an “overlapping multi-band” UWB system). For example, a multi-band system may employ eight radio frequency (RF) bands that overlap. The total amount of RF spectrum employed by all eight band may be 90 MHz (i.e, between 10 MHz and 100 MHz). This system may assign band  1  to the 10 to 30 MHz spectrum, band  2  to the 20 to 40 MHz spectrum, band  3  to the 30 to 50 MHz spectrum, band  4  to the 40 to 60 MHz spectrum, band  5  to the 50 to 70 MHz spectrum, band  6  to the 60 to 80 MHz spectrum, band  7  to the 70 to 90 MHz spectrum, and band  8  to the 80 to 100 MHz spectrum. It will also be appreciated that other numbers of RF bands, occupying different RF spectra, may also be employed.  
         [0086]     Alternatively, a non-overlapping twisted-pair wire media multi-band UWB communication system may be employed. In this embodiment, the same 90 MHz radio frequency spectrum may be occupied by 3 non-overlapping bands. For example, band  1  may occupy the spectrum between 10 and 40 MHz, band  2  may occupy the spectrum between 40 to 70 MHz and band  3  may occupy the spectrum between 70 to 100 MHz.  
         [0087]     Regardless of the type of UWB system employed (single-band, overlapping multi-band, non-overlapping multi-band, or other types of UWB systems), one feature of the present invention is that it reduces, or eliminates cross talk, while simultaneously increasing the bandwidth, or data transmission rate capability of a communication system employing twisted-pair wire media.  
         [0088]     As discussed above, electromagnetic energy on twisted-pair media may produce interference between the individual pairs of wires (i.e., cross talk). As an electromagnetic signal propagates through a first twisted-pair wire, an electromagnetic field is generated. The second twisted-pair wire picks-up this electromagnetic field and a second electromagnetic signal is induced in the second twisted-pair wire. This second electromagnetic signal is a potential source of interference. As the number of electromagnetic signals increases, the potential amount of interference also increases.  
         [0089]     In one method of the present invention, UWB pulses are transmitted at staggered, or otherwise designated, time intervals through each twisted-pair wire. In this embodiment, UWB pulses received during an inappropriate, or unanticipated time interval may be assumed to be due to cross talk, and ignored by the receiver. For example, UWB pulses are transmitted through a first twisted-pair wire. A UWB receiver receives UWB pulses from a second twisted-pair wire at about the time that the UWB pulses from the first twisted-pair wire are expected. The UWB pulses received from the second twisted-pair wire are then ignored.  
         [0090]     In another method of the present invention, UWB pulses may include one or more code sequences that are unique to each twisted-pair wire Within a cable comprising a group of twisted-pair wires. For example, the receiver may associate a timing code to a specific twisted-pair wire. The receiver may then ignore signals arriving at time periods that are non-compliant with the timing code for that twisted-pair wire.  
         [0091]     Referring to  FIG. 7 , in yet another method of the present invention, unique center frequencies may be assigned to each twisted-pair wire within a cable comprising a group of twisted-pair wires.  FIG. 7  illustrates different UWB pulses  150 ( a - h ), with each UWB pulse having a different center frequency. In this method, when a receiver detects a non-compliant, or unexpected UWB pulse center frequency on a twisted-pair wire assigned to a different center frequency, the non-compliant UWB pulse may then be disregarded.  
         [0092]      FIG. 7  also illustrates another method of the present invention, that comprises combinations of the above-described methods. As shown in  FIG. 7 , UWB pulses may be transmitted at different time periods, with each UWB pulse having a specific center frequency. A receiver may then ignore signals arriving at the same time periods and center frequencies on other twisted-pair wires.  
         [0093]     In another method of the present invention, a pseudo-random sequence generator may be employed to generate the UWB pulse timing and/or center frequencies. In this embodiment, the UWB pulse transmission timing and/or the UWB pulse center frequency may follow pseudo-random codes. In yet another embodiment, the pseudo-random codes employed on each twisted-pair wire may be orthogonal. There are a number of methods of orthogonal pseudo-random code generation known in the art of communications that may be employed by this embodiment of the present invention.  
         [0094]     Referring now to  FIG. 8 , a functional block illustration of a transmitter  120  and receiver  125  constructed according to one embodiment of the present invention is illustrated. The transmitter  120  includes a data processing module (that may include a digital processor), an ultra-wideband pulse generator, and a plurality of filters and amplifiers (“Amps”). The data to be transmitted is received by the data processing module. The data processing module may provide data modulation and timing functions. Data modulation may employ a variety of different modulation methods, as described above, and others known to one skilled in the art. For example, modulation methods may include UWB pulse position, timing, amplitude, frequency, or phase modulation.  
         [0095]     Transmitter  120  may also include a timing generator (not shown) that may be configured to send timing signals to the pulse generator at a fixed timing interval or alternatively may send timing signals at a pseudo-random timing interval. In this embodiment, the transmitter  120  may also include a timing generator that has a pseudo-random timing sequence capability. In this embodiment, the pseudo-random timing interval may be used to modulate data or alternatively may represent a pseudo-random code used to reduce cross talk between twisted-pair wires, as discussed above.  
         [0096]     Again referring to  FIG. 8 , receiver  125  may comprise a plurality of filters and amplifiers (“Amps”), a UWB pulse detector module, and a data processing module. The UWB pulses, or signal is received from the twisted-pair medium, filtered and amplified. The amplifier may be a low noise amplifier and may additionally have an automatic gain control function. The plurality of filters may include low-pass filters and band-pass filters. The UWB pulse detector module may comprise a single UWB pulse detector, in the embodiment where the UWB pulse occupies substantially the entire available radio frequency spectrum (i.e., in a “single-band” UWB system, described above). The data processing module may comprise a data demodulation capability and a UWB pulse timing detection capability. Generally, the data demodulation capability of the receiver  125  is matched to the transmitter&#39;s  120  data modulation capability. In addition, an UWB pulse timing detector (not shown) may be used for clock extraction and validation of time of arrival of UWB pulses against the expected time of arrival of the UWB pulses.  
         [0097]     Referring to  FIG. 9 , another embodiment UWB receiver is illustrated. This receiver is constructed to receive UWB pulses having different center frequencies that reduce cross talk or provide data modulation. A plurality of band-pass filters  130  having similar radio frequency bandwidths and different center frequencies are included. The pulse detector module may comprise an array of pulse detectors  135  that determine which radio frequency band the incoming UWB pulse, or signal resides in.  
         [0098]     Referring now to  FIG. 10 , another embodiment UWB transmitter is illustrated. In this embodiment, the incoming UWB pulses, or signal is filtered by a plurality of band-pass filters  105 . Each filter  105  may have a different center frequency and a substantially similar bandwidth. In one embodiment, the bandwidth of the filters  105  approximates the bandwidth limitation of the twisted-pair media. The output of the filters  105  comprises a plurality of UWB pulse, or signals with different center frequencies. A switching mechanism  115  is controlled to select which UWB pulse, or signal is transmitted. In this manner, specific twisted-pair wires may transmit different center frequency UWB pulses, or signals. Because the cross talk induced by the UWB pulses will have a similar frequency content to the signal that caused it, the receiver (shown in  FIG. 9 ) may ignore the interfering signal.  
         [0099]     As described above, and illustrated in  FIG. 11 , UWB pulses or signals may be generated to fit the bandwidth of the twisted-pair medium. In some embodiments the pulse durations ΔT may exist as long as a millisecond (generating about a 1 Kilo Hertz radio frequency bandwidth), while in other applications pulse durations ΔT may be as short as 10 picoseconds (generating about a 10 Giga Hertz radio frequency bandwidth). For example, as shown in  FIG. 11 , short duration UWB pulse P 0  has a frequency bandwidth Bw 1 , centered at F 0 , medium duration UWB pulse P 1  has a frequency bandwidth Bw 2 , centered at F 1 , and long duration UWB pulse P 2  has a frequency bandwidth Bw 3 , centered at F 2 .  
         [0100]     Thus, it is seen that an apparatus and method for transmitting and receiving ultra-wideband signals through a wired medium is provided. One skilled in the art will appreciate that the present invention can be practiced by other than the above-described embodiments, which are presented in this description for purposes of illustration and not of limitation. The description and examples set forth in this specification and associated drawings only set forth preferred embodiment(s) of the present invention. The specification and drawings are not intended to limit the exclusionary scope of this patent document. Many designs other than the above-described embodiments will fall within the literal and/or legal scope of the following claims, and the present invention is limited only by the claims that follow. It is noted that various equivalents for the particular embodiments discussed in this description may practice the invention as well.