Abstract:
A multi-line ADSL modem ( 12 ) and network ( 10 ) whereby the multi-line ADSL modem ( 12 ) has connections to several ADSL modems ( 14 ) at a central office (CO) ( 16 ) through a master loop ( 18 ), shared loops ( 20, 22 ), and/or broadcast loops ( 84 ). The master loop ( 18 ) provides the basic connection between the multi-line ADSL modem ( 12 ) and the CO modem ( 14 ) at the central office ( 16 ) while maintaining regular telephone service. The shared loops allow the multi-line ADSL modem to share the transmission capacity with other modems. The multi-line ADSL modem is able to receive broadcast data from the central office where several loops are configured as a broadcast loop for downstream transmission only, but which can also be configured for upstream communication transmission only or in combination with downstream transmission to provide bi-directional broadband communications.

Description:
PRIORITY 
   This application claims priority of Provisional U.S. Patent application Ser. No. 60/156,475 filed Sep. 28, 1999. 
   CROSS REFERENCE TO RELATED APPLICATIONS 
   Cross reference is made to commonly assigned U.S. patent application Ser. No. 9/651,976 entitled “Multi-Client ADSL Modem” filed Aug. 31, 2000, now U.S. Pat. No. 7,031,380 B1 the teachings included herein by reference. 

   FIELD OF THE INVENTION 
   The present invention is generally related to communication networks, and more specifically to networks adapted to communicate over standard residential 2-wire phone lines including twisted pair loops adapted to support ADSL communications. 
   BACKGROUND OF THE INVENTION 
   Asymmetrical Digital Subscriber Lines (ADSL) is an ANSI standard identified as TI.413 issued in 1995 which presents the electrical characteristics of the ADSL signal as it should appear at a network interface. Generally, ADSL is a high-speed communication technology that allows one client modem, such as that at a remote terminal (RT), to be connected to only one central office (CO) modem through one twisted pair telephone line forming a loop. Typically, discrete multi-tone (DMT) modulation is the chosen line code technique standard in a typical ADSL system. Upstream communications, such as from RT to CO, and downstream communications, such as CO to RT, are divided from one another using frequency division multiplexing (FDM) or using echo canceling, allowing the frequency band for upstream communications to be shared with downstream communications thereby increasing the overall data rate over the loop. 
   Disadvantageously, the ADSL standard allows only one pair of modems (CO and RT) to communicate over the loop at the same time. The CO modem may send a downstream signal while simultaneously receiving an upstream signal from the RT, frame by frame. Similarly, the RT modem may receive the downstream communication from the CO modem and simultaneously send upstream communication signals to the CO modem. 
   Since the standardization of ADSL communications, there have been introduced varied implementations and customized uses of the ADSL technology, such as disclosed in commonly assigned U.S. Pat. No. 5,479,447 entitled “Method and Apparatus for Adaptive, Variable Bandwidth, High-Speed Data Transmission of a Multi-Carrier Signal over Digital Subscriber Lines, the teachings of this patent included herein by reference. 
   As technology evolves and the world becomes more connected including providing access to high-speed internet devices, digital TV (DTV), and even high-definition TV (HDTV), increased bandwidth will be required to connect such devices which may be located at a home or small office. Today, a single pair of twisted telephone line does not provide sufficient bandwidth to allow communications at the data rate required for some of these devices, which is about 20 Mbps for HDTV in the case of line conditioning. Although cable modems may be designed to reach up to 40 Mbps, there are many users that are required to share this data bandwidth. This means that the 40 Mbps is the burst data rate for one user, or the maximum data rate for all users. 
   There is desired a higher bandwidth modem and communication network that provides for a higher data rate access than that provided by conventional ADSL modems operating over a single loop of twisted pair of telephone wire. Such an improved higher data rate communication is desired to be compatible with ADSL standards, and which can support high speed communications suitable for the internet, digital TV, and even HDTV. 
   SUMMARY OF THE INVENTION 
   The present invention achieves technical advantages as an improved modem, communication network, and method of operation thereof that provides a much higher burst data rate than standard ADSL technology without increasing the number of telephone lines. A multi-line ADSL modem is provided that has connections to several ADSL modems at a central office (CO) through a master loop, as well as through shared loops and/or broadcast loops. The master loop provides the basic connection between the multi-line ADSL modem and the corresponding CO modem while maintaining regular telephone service. By accessing and using the additional shared loops, such as those serving other residential devices, the shared loop allows the multi-line modem, preferably a multi-line ADSL modem, to share the transmission capacity of the shared loop with other residential modems. Advantageously, the multi-line ADSL modem is able to receive high speed broadband broadcast data from the central office when several loops are configured as a broadcast loop such as for downstream transmission. Optionally, several loops can also be configured for broadband upstream communication if desired. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  illustrates a block diagram of a 3-line ADSL system whereby a multi-line modem has one master loop connection for itself, and also shares two other loops thereby providing additional access capacity; 
       FIG. 2  illustrates a multi-line ADSL system with a multi-line ADSL modem connected to three pairs of loops with additional high-pass filters facilitating the use of the additional loops; 
       FIG. 3  illustrates a single-user model in a multi-line ADSL system, the single user model allowing a multi-line ADSL modem to share loops without other ADSL modems in operation; 
       FIG. 4  illustrates a multi-user model in a multi-line ADSL system, whereby the multi-user model allows a multi-line ADSL modem to share loops with other ADSL modems that are in operation; and 
       FIG. 5  illustrates the broadcast model in a multi-line ADSL system, this broadcast model being a special multi-user model which allows a multi-line ADSL to, for instance, only listen to and receive the broadband communication from the broadcast loop. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   Referring now to  FIG. 1 , there is illustrated generally at  10  a communication network having a single residential multi-line modem  12  serving a remote terminal  13  and adapted to communicate with a corresponding central office (CO) modem  14  serving a communications terminal  15  at a central office  16  via a master loop  18  comprising a conventional twisted pair telephone line. Advantageously, the multi-line modem (RT)  12  is also adapted to share adjacent loops  20  and  22  connected to the common central office  16  and serving other residential customers which may be served by a single line modem  24 , a multi-line modem  12 , or just a Plain-Old-Telephone-System (POTS) device  26  such as phone set or fax machine. 
   As shown in  FIG. 1 , the multi-line modem  12  is seen to be connected to the respective master loop  18 , while also being connected through a high-pass filter  30  to each of the shared loops  20  and  22  to separate out low frequency communications, such as voice communications, resident on the shared loops from the multi-line modem  12 . As shown in  FIG. 1  the multi-line terminal  12  is connected to two other shared loops  20  and  22  serving nearby residential customers which are primarily served by different respective CO modems  14  located at the same and common central office  16 . Although two additional shared loops are shown to be connected to the multi-line modem  12 , it is envisioned that only one shared loop, or more than two shared loops, may be connected thereto depending on the desired bandwidth to be available to a customer served by the multi-line modem  12 . As illustrated in  FIG. 1 , the bandwidth of the communication between a user of multi-line modem  12  is increased at least threefold to provide a significantly greater burst data rate over a single loop. 
   Preferably, the multi-line modem  12 , as well as the central office modems  14  are all capable of and adapted to communicate with each other in a format compatible with ADSL standards, as well as modifications thereto. 
   Referring now to  FIG. 2 , there is illustrated in more detail communication network  10  illustrating a frequency splitter  32  being provided for each standard user having both a customer premise network  34  and having a telephone set, voice-band modem or ISDN terminal  36 . Advantageously, a frequency splitter  38  is provided to service the multi-line modem  12 . Splitter  38  has a low pass filter  40  and high pass filter  42  servicing and connected to the master loop  18 , whereby the low frequency signals are separated out by the low pass filter  40  to the telephone set, voice-band modem, or ISDN terminal  36 , and the high pass filter  42  splitting the high frequency signals to the multi-line modem  12 . An additional high pass filter  44  is provided in splitter  38  to separate out the high frequency signals of each of the shared loops  20  and  22  for communication to the multi-line modem  12 . The high pass filters  42  and  44  provide the high frequency components of both the master loop  18  as well as the shared loops  20  and  22  such that they are all available via the multi-line modem  12  to the high data rate customer premise network shown at  46 . 
   A corresponding splitter  50  is provided at the central office  16  at the opposing end of the respective loop to separate the low frequency signals via a low pass filter  52  to a narrowband network  54 , and the high frequency signals via a high pass filter  56  to a broadband network  58 . The combination of the splitters  50  and the corresponding splitters  32  and  38  direct the broadband network communications over the respective loops to the customer premise networks, with the communications of the narrowband networks communications being directed to the terminals  36 . Advantageously, the high pass filters  42  and  44  separate out the low frequency voice band signals from the shared loop signals for minimum interference. The shared loops may be configured to serve a single line modem, or a multi-line modem, or simply a POTS device such as a phone set or fax machine. The respective high pass filters for the respective modem minimize the interference between the voice band signals and the ADSL band signals. 
   The multi-line modem  12  advantageously shares one or more other loops serving other customer terminals, without causing interference with the respective voice band signals, such that the improved customer premise network  46  served by the multi-line modem  12  achieves a significantly higher data transmission rate than that achievable with only one twisted pair of conductors forming the master loop  18 . 
   Referring now to  FIG. 3 , there is depicted a single-user model  60  of the multi-line ADSL system with the multi-line modem  12  connected to the master loop  18 , as well as to the shared loops  20  and  22  as shown in  FIG. 2 . The master loop is shown to be connected to a respective ATU-C modem  14 , and is adapted to simultaneously time share one or more of the adjacent loops  20  and  22  serving other terminals located in close proximity to modem  12  to achieve the significantly higher data rate, such as 40 Mbps or more. According to the present invention, the shared loops  20  and  22  may be configured, such as at the multi-line modem  12 , so as to provide only downstream communications from the respective CO modems  14  to the multi-line modem  12 . Optionally, the communications may be set up for bi-directional broadband communications to facilitate expanded bandwidth communications for both upstream and downstream communications. 
   Referring now to  FIG. 4 , a multi-user model of a multi-line ADSL system is shown at  70 . Each of the multi-line ATU-R modems  12  are seen to be connected to and communicate over a respective master loop  18 , and at the same time each of these multi-line modems  12  is configured to share one or more loops serving other modems  24  for achieving a higher data rate. The shared loops may be configured to provide to modem  12  downstream communications only, or providing both upstream and downstream bi-directional broadband communications. The master loop  18  is always set up and configured for both upstream and downstream communications. 
   The shared loops can be configured to share information in frames, known as time division, using different tones, known as frequency division, or using different codes known as code division. As shown, there are multiple multi-line modems  12  connected to share common shared loops in the multi-user mode. 
   Referring now to  FIG. 5 , a broadcast model of a multi-line ADSL system  80  is shown. Each multi-line ATU-R modem  12  is seen to be connected to a respective master loop  18 , and at the same time configured to time share one or more of the other adjacent loops shown at  20  for achieving a higher data rate than that achievable by communicating ADSL standard signals over just one loop. The shared loops  20  may be configured for downstream communications only, or to facilitate both upstream and downstream communications. The master loop  18  is typically set up for upstream and downstream communications all the time. Again, the shared loops can be shared in frames, (time division), tones (frequency division), or code division such as that similar to CDMA technology used in wireless networks. On the other hand, a broadcast service system  82  can integrate several shared loops into a broadcast service system and integrate several shared loops into a broadcast loop  84 . Each of the multi-line modems  12  can receive the broadcast data from the broadcast loop  84  with or without a master loop connected to the dedicated modems  12 . 
   In summary, the present invention achieves technical advantages as an improved multi-line modem and network, and method of using the same, whereby the improved modem communicates over both a master loop and adjacent shared loops to achieve significantly higher data rates so as to facilitate use of high data rate devices including internet communications, digital video and HDTV communication signals. No additional loops are required to be installed as a multitude of twisted pair conductor loops are already installed providing communications between the central office (CO) and the plurality of adjacent customers served by a common central office. The present invention takes advantage of the ADSL standard communications which are well suited for communication over these twisted pair loops. The multi-line modem  12  is specifically configured to share the adjacent shared loops and handle the bi-directional communications as a transceiver between the loops and the customer premise network. The multi-line modem  12  has appropriate hardware and/or software to split high data rate upstream communications from the served customer premise network to the appropriate loops providing a higher bandwidth than that provided by a single loop. Likewise, the multi-line modem  12  is adapted to combine the received downstream communications from each of the respective loops to form a single high data rate signal which is provided to the served customer premise network  46 . Again, communications over each of the loops is configures to be compatible with ADSL standards, while the communication signal provide to the customer premise network may be configures to be compatible with any number of standards including high definition television (HDTV), digital video and high speed internet access. The present invention is a low cost high bandwidth network which does not require the installation of any additional loops or the upgrade thereof while achieving a high data rate communication network. 
   Though the invention has been described with respect to a specific preferred embodiment, many variations and modifications will become apparent to those skilled in the art upon reading the present application. It is therefore the intention that the appended claims be interpreted as broadly as possible in view of the prior art to include all such variations and modifications.