Abstract:
A “Smart DSL System” for addressing the performance objectives of LDSL and examples of smart systems for LDSL are disclosed. In accordance with embodiments of the invention, there is disclosed a method for implementing smart DSL for LDSL systems. Embodiments of the method include presenting a number of spectral masks that are available on the LDSL system, and selecting from the number of spectral masks an upstream mask and a downstream mask wherein the upstream mask and the downstream mask exhibit complimentary features.

Description:
RELATED APPLICATIONS  
       [0001]    The present invention claims priority to U.S. Provisional Application Nos. 60/488,804 filed Jul. 22, 2003 and Ser. No. 60/426,796 filed Nov. 18, 2002, the contents of which are incorporated herein by reference in their entirety.  
         [0002]    This application is related to copending U.S. Patent Applications titled “SYSTEM AND METHOD FOR SELECTABLE MASK FOR LDSL,” (Attorney Docket No. 56162.000456) which claims priority to U.S. Provisional Patent Application No. 60/441,351, “ENHANCED SMART DSL FOR LDSL,” (Attorney Docket No. 56162.000483) which claims priority to U.S. Provisional Application No. 60/488,804 filed Jul. 22, 2003 and “POWER SPECTRAL DENSITY MASKS FOR IMPROVED SPECTRAL COMPATIBILITY” (Attorney Docket No. 56162.000485) which claims priority to U.S. Provisional Application No. 60/491,268 filed Jul. 31, 2003, all filed concurrently herewith. 
     
    
     
       BACKGROUND OF THE INVENTION  
         [0003]    1. Field of the Invention  
           [0004]    This invention relates to digital subscriber lines (DSL) and to smart systems for implementing Long reach Digital Subscriber Lines (LDSL).  
           [0005]    2. Description of Related Art  
           [0006]    High level procedures for meeting stated objectives for Long reach Digital Subscriber Line (LDSL) transmissions are disclosed. Some objectives for LDSL have been defined in publications available from standards organizations such as the International Telecommunications Union (ITU). For example, ITU publications OC-041R1, OC-045, OC-073R1, OJ-030, OJ-036, OJ-060, OJ-061, OJ-062, OJ-200R1, OJ-200R2, OJ-201, OJ-60R1, OJ-60R2 and OJ-210 set forth some LDSL objectives. Other objectives, standards and criteria for LDSL are also possible and may be accommodated by the disclosed inventions.  
           [0007]    One LDSL target objective is to achieve a minimum payload transmission of 192 kb/s downstream and 96 kb/s upstream on loops having an equivalent working length of 18 kft 26 gauge cable in a variety of loop and noise conditions. One difficulty in achieving these target transmission rates is the occurrence of crosstalk noise.  
           [0008]    The crosstalk noise environments that may occur for the above bit rate target objective are varied. For example, noise environments may include Near-end cross talk (NEXT), Far-end cross talk (FEXT), disturbance from Integrated Services Digital Networks (ISDN), High Speed Digital Subscriber Lines (HDSL), SHDSL, T1, and Self-disturbers at both the Central Office (CO) and Customer Premise Equipment (CPE) ends. NEXT from HDSL and SHDSL tend to limit the performance in the upstream channel, while NEXT from repeatered T1 AMI systems tend to severely limit the downstream channel performance. An additional source of noise is loops containing bridged taps that degrade performance on an Asymmetric Digital Subscriber Line (ADSL) downstream channel more so than the upstream channel.  
           [0009]    Another drawback of existing systems is that it appears very difficult to determine a single pair of Upstream and Downstream masks that will maximize the performance against any noise-loop field scenario, while ensuring spectral compatibility and, at the same time, keeping a desirable balance between Upstream and Downstream rates.  
           [0010]    One approach for LDSL relies on different Upstream and Downstream masks exhibiting complementary features. Realistically, all these chosen masks are available on any LDSL Platform. At the modem start up, based on a certain protocol, the best Upstream-Downstream pair of masks is picked up. Whether the best pair is manually chosen at the discretion of the operator, or automatically selected, this concept is identified as “smart DSL for LDSL”.  
           [0011]    There are many reasons to implement smart DSL. For example, non-smart DSL systems may implement a single mask for upstream and downstream transmissions. A drawback with this approach is that the use of a single mask may prevent LDSL service in areas of the United States dominated by T1 noise.  
           [0012]    In addition, the use of a single mask is a drawback because the existence of other spectrally compatible masks cannot be ruled out. LDSL service providers will want to have access to an array of mask/tools provided they are spectrally compatible. Service providers may decide to use only one mask according to the physical layer conditions, or any combination of masks for the same or other reasons.  
           [0013]    Another advantage of Smart DSL is that it is a good way to handle providing LDSL services in different countries. For example, so far, LDSL work has focused on SBC requirements. As a result, it is risky of, for example, a US-based LDSL provider to rely on the ability to apply any masks that pass SBC tests to Europe, China or Korea. LDSL is a difficult project and essential for all the countries. Therefore, any scheme for LDSL standardization that takes into account merely SBC physical layer and cross talk requirements may jeopardize the ADSL reach extension in non-standard LDSL countries. Other drawbacks of current systems also exist.  
         SUMMARY OF THE INVENTION  
         [0014]    A “Smart DSL System” for addressing the performance objectives of LDSL and examples of smart systems for LDSL are disclosed.  
           [0015]    In accordance with embodiments of the invention, there is disclosed a method for implementing smart DSL for LDSL systems. Embodiments of the method may comprise presenting a number of spectral masks that are available on the LDSL system, and selecting from the number of spectral masks an upstream mask and a downstream mask wherein the upstream mask and the downstream mask exhibit complimentary features.  
           [0016]    In some embodiments the method may further comprise selecting the upstream mask and the downstream mask during a modem start up period. Still further, embodiments of the invention may comprise selecting the upstream mask and the downstream mask manually or automatically.  
           [0017]    In accordance with some embodiments of the invention, there is disclosed a method for implementing smart DSL for LDSL systems. In some embodiments, the method may comprise defining a candidate system to be implemented by an LDSL system, optimizing criteria associated with the candidate system, and selecting a candidate system to implement in an LDSL system.  
           [0018]    In accordance with some embodiments of the invention, the method may further comprise determining features of upstream and downstream transmission. The method may further comprise determining one or more of: cut-off frequencies, side lobe shapes, overlap, partial overlap or FDD characteristics.  
           [0019]    In some embodiments, the method may further comprise optimizing criteria associated with the candidate system to fulfill upstream and downstream performance targets and selecting a spectral mask for use with upstream or downstream transmission.  
           [0020]    In accordance with some embodiments of the invention there is provided a method for implementing smart DSL for LDSL systems. In some embodiments the method may comprise selecting a spectral mask based upon performance criteria;, and activating the selected spectral mask based at least one of customer premise or central office capabilities.  
           [0021]    In accordance with further aspects of the invention, the method may further comprise selecting the spectral mask is performed manually or automatically. Other advantages and features of the invention are discussed below. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]    [0022]FIG. 1 is a graph illustrating peak values for U1 and D1 PSD masks according to embodiments of the invention.  
         [0023]    [0023]FIG. 2 is a graph illustrating peak values for U2 and D2 PSD masks according to embodiments of the invention.  
         [0024]    [0024]FIG. 3 is a graph illustrating average values for U3 and D3 PSD templates according to embodiments of the invention.  
         [0025]    [0025]FIG. 4 is a bar chart illustrating upstream rate, noise case #1, for ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0026]    [0026]FIG. 5 is a bar chart illustrating upstream rate, noise case #2, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0027]    [0027]FIG. 6 is a bar chart illustrating upstream rate, noise case #3, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0028]    [0028]FIG. 7 is a bar chart illustrating upstream rate, noise case #4, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0029]    [0029]FIG. 8 is a bar chart illustrating upstream rate, noise case #5, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0030]    [0030]FIG. 9 is a bar chart illustrating upstream rate, noise case #6, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0031]    [0031]FIG. 10 is a bar chart illustrating upstream rate, noise case #7, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0032]    [0032]FIG. 11 is a bar chart illustrating upstream rate, noise case #T1, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0033]    [0033]FIG. 12 is a bar chart illustrating downstream rate, noise case #1, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0034]    [0034]FIG. 13 is a bar chart illustrating downstream rate, noise case #2, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0035]    [0035]FIG. 14 is a bar chart illustrating downstream rate, noise case #3, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0036]    [0036]FIG. 15 is a bar chart illustrating downstream rate, noise case #4, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0037]    [0037]FIG. 16 is a bar chart illustrating downstream rate, noise case #5, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0038]    [0038]FIG. 17 is a bar chart illustrating downstream rate, noise case #6, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0039]    [0039]FIG. 18 is a bar chart illustrating downstream rate, noise case #7, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0040]    [0040]FIG. 19 is a bar chart illustrating downstream rate, noise case #T1, ADSL2, M OJ-074, NON EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0041]    [0041]FIG. 20 is a bar chart illustrating upstream rate, noise case #1, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0042]    [0042]FIG. 21 is a bar chart illustrating upstream rate, noise case #2, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0043]    [0043]FIG. 22 is a bar chart illustrating upstream rate, noise case #3, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0044]    [0044]FIG. 23 is a bar chart illustrating upstream rate, noise case #4, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0045]    [0045]FIG. 24 is a bar chart illustrating upstream rate, noise case #5, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0046]    [0046]FIG. 25 is a bar chart illustrating upstream rate, noise case #6, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0047]    [0047]FIG. 26 is a bar chart illustrating upstream rate, noise case #7, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0048]    [0048]FIG. 27 is a bar chart illustrating upstream rate, noise case #T1, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0049]    [0049]FIG. 28 is a bar chart illustrating downstream rate, noise case #1, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0050]    [0050]FIG. 29 is a bar chart illustrating downstream rate, noise case #2, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0051]    [0051]FIG. 30 is a bar chart illustrating downstream rate, noise case #3, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0052]    [0052]FIG. 31 is a bar chart illustrating downstream rate, noise case #4, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0053]    [0053]FIG. 32 is a bar chart illustrating downstream rate, noise case #5, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0054]    [0054]FIG. 33 is a bar chart illustrating downstream rate, noise case #6, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0055]    [0055]FIG. 34 is a bar chart illustrating downstream rate, noise case #7, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0056]    [0056]FIG. 35 is a bar chart illustrating downstream rate, noise case #T1, ADSL2, M OJ-074, EC Smart LDSL systems in accordance with embodiments of the invention.  
         [0057]    [0057]FIG. 36 illustrates a flow diagram for selecting a pair of masks in a smart DSL system in accordance with embodiments of the invention.  
         [0058]    [0058]FIG. 37 is a state diagram illustrating options for selecting a pair of masks in a smart DSL systems in accordance with embodiments of the invention.  
         [0059]    [0059]FIG. 38 illustrates an option for implementing smart DSL systems in accordance with embodiments of the invention.  
         [0060]    [0060]FIG. 39 illustrates an option for implementing smart DSL systems in accordance with embodiments of the invention.  
         [0061]    [0061]FIG. 40 illustrates an option for implementing smart DSL systems in accordance with embodiments of the invention. 
     
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS  
       [0062]    Smart DSL Concept for LDSL.  
         [0063]    This section defines a Smart DSL concept for LDSL. In some embodiments, operating with smart DSL systems for LDSL may include the below listed steps. The first and second steps may be completed, in some embodiments, during a standardization process and other steps may be performed during a modem&#39;s handshake/initialization phase in order to optimize the performance for any type of loops and noises.  
         [0064]    Step 1. Smart DSL Systems members for LDSL (S).  
         [0065]    In some embodiments it is preferable to complete step 1 during standardization processes. Alternatively, step 1 may be performed off line, for example, if no standardization is at stake.  
         [0066]    In some embodiments, the first step consists of defining candidate systems that aim to be picked up based on optimization criteria defined below. Typically, these candidate systems may exhibit sufficient versatility features for both Upstream and Downstream spectra, such as cut off frequencies, side lobes shapes, overlap, partial overlap, FDD characteristics, etc.  
         [0067]    In some embodiments it may be desirable for candidate systems to also meet additional constraints. For example, an additional constraint may be that no new channel coding scheme should be considered in the candidate systems. In this manner, smart DSL systems in accordance with the invention exhibit several degrees of freedom that are summarized in what follows by parameter set S.  
         [0068]    Step 2. Optimization criteria (C).  
         [0069]    In some embodiments, it is preferable that the second step be completed during the standardization process. Alternatively, the second step may be completed off line if no standardization is at stake.  
         [0070]    The second step comprises defining optimization criteria. Optimization criteria drive smart DSL systems members definition and, of course, the performance outcomes. For some embodiments, optimization criteria (C ) may be summarized as covering Upstream and Downstream performance targets. In addition, optimization criteria may cover the margin within which performance targets should be met, such as, whether the deployment is Upstream or Downstream limited. The last point is important since often, in order to keep the optimization process simple priority should be given to Upstream or Downstream channels.  
         [0071]    In some embodiments, optimization criteria may also comprise spectral compatibility requirements. This criteria may also include assumptions about neighboring services. Other optimization criteria are also possible.  
         [0072]    Step 3. Choice of an optimal system amongst the smart DSL systems candidates (S*).  
         [0073]    In some embodiments it may be preferable to complete step 3 during handshake/initialization. Completing step 3 during handshake/initialization may enable better handling of any type of loops and noise/cross talk conditions. Alternatively, this step could be completed off line, for example, if the operator has accurate prior knowledge of loops and noise conditions.  
         [0074]    In some embodiments, completion of step 3 may be as simple as picking up one of two masks already defined. In other embodiments, completion of step 3 may comprise tuning a continuous parameter such as a cut off frequency. Other methods of completing step 3 are also possible.  
         [0075]    In some embodiments, the outcome of step 3 may comprise an optimal system (S*) that will be run by the modem in the conditions that lead to its optimality.  
         [0076]    Two Examples of Smart DSL system for LDSL, based on SBC requirements.  
       EXAMPLE 1  
       [0077]    Definition of the Masks to be used in the two smart systems.  
         [0078]    Three Upstream masks U1, U2, U3 and three Downstream masks D1, D2, D3 are used in what follows to define embodiments of smart systems. U1 (dashed line) and D1 (solid line) masks are plotted in FIG. 1. Note that in this section the masks for peak values are defined. As defined by some standards, the PSD templates, or average PSD values, are 3.5 dB lower than the mask values. Tables 1 and 2 show some values for U1 and D1 (respectively) according to some embodiments of the invention.  
                             TABLE 1                           U1 PSD Mask Definition, peak values                Frequency Band f               (kHz)   Equation for the PSD mask (dBm/Hz)                       0 &lt; f ≦ 4   −97.5, with max power in the in               0-4 kHz band of +15 dBrn           4 &lt; f ≦ 25.875   −92.5 + 23.43 × log 2 (f/4);           25.875 &lt; f ≦ 60.375   −29.0           60.375 &lt; f ≦ 90.5   −34.5 − 95 × log 2 (f/60.375)           90.5 &lt; f ≦ 1221   −90           1221 &lt; f ≦ 1630   −99.5 peak, with max power in               the [f, f + 1 MHz] window of               (−90 − 48 × log 2 (f/1221) + 60) dBm           1630 &lt; f ≦ 11 040   −99.5 peak, with max power in               the [f, f + 1 MHz] window of               −50 dBm                      
 
         [0079]    [0079]                             TABLE 2                           D1 PSD Mask Definition, peak values                Frequency Band f               (kHz)   Equation for the PSD mask (dBm/Hz)                       0 &lt; f ≦ 4   −97.5, with max power in the in               0-4 kHz band of +15 dBrn           4 &lt; f ≦ 25.875   −92.5 + 20.79 × log 2 (f/4)           25.875 &lt; f ≦ 81   −36.5           81 &lt; f ≦ 92.1   −36.5 − 70 × log 2 (f/81)           92.1 &lt; f ≦ 121.4   −49.5           121.4 &lt; f ≦ 138   −49.5 + 70 × log 2 (f/121.4)           138 &lt; f ≦ 353.625   −36.5 + 0.0139 × (f − 138)           353.625 &lt; f ≦ 569.25   −33.5           569.25 &lt; f ≦ 1622.5   −33.5 − 36 × log 2 (f/569.25)           1622.5 &lt; f ≦ 3093   −90           3093 &lt; f ≦ 4545   −90 peak, with maximum power in               the [f, f + 1 MHz]               window of               (−36.5 − 36 × log 2 (f/1104) + 60) dBm           4545 &lt; f ≦ 11040   −90 peak, with maximum power in               the [f, f + 1 MHz]               window of −50 dBm                        
         [0080]    According to some embodiments of the invention U2 (dashed line) and D2 (solid line) spectrum masks may be plotted as shown in FIG. 2. Note that, as above, the masks for peak values are defined. The PSD templates, or average PSD values, are 3.5 dB lower than the mask values. Tables 3 and 4 show some values for U2 and D2 (respectively) in accordance with some embodiments of the invention.  
                             TABLE 3                           U2 Mask Definition, peak values                Frequency Band f               (kHz)   Equation for the PSD mask (dBm/Hz)                       0 &lt; f ≦ 4   −97.5, with max power in the in               0-4 kHz band of +15 dBrn           4 &lt; f ≦ 25.875   −92.5 − 22.5 × log 2 (f/4);           25.875 &lt; f ≦ 86.25   −30.9           86.25 &lt; f ≦ 138.6   −34.5 − 95 × log 2 (f/86.25)           138.6 &lt; f ≦ 1221   −99.5           1221 &lt; f ≦ 1630   −99.5 peak, with max power in               the [f, f + 1 MHz] window of               (−90 − 48 × log 2 (f/1221) + 60) dBm           1630 &lt; f ≦ 11 040   −99.5 peak, with max power in               the [f, f + 1 MHz] window of               −50 dBm                      
 
         [0081]    [0081]                                           TABLE 4                           D2 Mask Definition, peak values                Starting Frequency   Starting PSD mask value           (kHz)   (dBm/Hz)                            0.000000   −98.000000           3.990000   −98.000000           4.000000   −92.500000           80.000000   −72.500000           120.740000   −47.500000           120.750000   −37.800000           138.000000   −36.800000           276.000000   −33.500000           677.062500   −33.500000           956.000000   −62.000000           1800.000000   −62.000000           2290.000000   −90.000000           3093.000000   −90.000000           4545.000000   −110.000000           12000.000000   −110.000000                        
         [0082]    Similarly, tables 5 and 6 give the breakpoints of U3 and D3 PSD Templates (average values) in accordance with some embodiments of the invention. FIG. 3 shows U3 (dashed line) and D3 (solid line) according to some embodiments of the invention.  
                                           TABLE 5                           U3 Spectrum PSD Template, average       values                Frequency   Nominal Upstream PSD           [KHz]   [dBm/Hz]                            0   −101.5           4   −101.5           4   −96           25.875   −36.30           103.5   −36.30           164.1   −99.5           1221   −99.5           1630   −113.5           12000   −113.5                      
 
         [0083]    [0083]                                           TABLE 6                           D3 Spectrum PSD Template, average       values                Frequency   Nominal Downstream PSD           [kHz]   [dBm/Hz]                            0   −101.5           4   −101.5           4   −96           80   −76           138   −47.5           138   −40           276   −37           552   −37           956   −65.5           1800   −65.5           2290   −93.5           3093   −93.5           4545   −113.5           12000   −113.5                        
         [0084]    Smart system scenario detection.  
         [0085]    In this scenario, it is assumed that the Smart LDSL system has the capability either to analyze a priori the cross talk/physical layer conditions, or to pick up a mask after testing all of them based on performance and spectral compatibility criteria. Under this feature, all the modems located in the same area will detect the same type of cross talk/impairments. Therefore, the worst case catastrophic scenario based on the use of all the possible masks at any location happens to be a completely unrealistic view for a genuine smart system. This feature was incorporated with success in the already deployed smart enhanced Annex C for Japan.  
       EXAMPLE 1  
       [0086]    NON EC Smart LDSL  
         [0087]    Definition  
         [0088]    In this exemplary embodiment, a first smart system makes use of U1, U2, U3 and DI, D3 masks. According to the features of all these masks, no Echo canceller is required by this embodiment of a smart system that will be identified as NON EC Smart LDSL.  
         [0089]    Simulation Results  
         [0090]    Tables 7 and 8 gives the ADSL2 upstream and downstream performance for calibration purposes.  
                                                                                                             TABLE 7                           ADSL2 Upstream Channel performance                upstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    ADSL2   xDSL 10   1107   1107   596   294   305   570   646   1133           xDSL 11   884   884   319   120   130   291   361   894           xDSL 12   846   846   275   90   102   248   314   854           xDSL 13   692   692   142   48   54   99   163   697           xDSL 160   969   969   406   141   157   380   452   986           xDSL 165   925   925   360   116   130   330   404   944           xDSL 170   881   881   313   94   106   287   354   897           xDSL 175   837   837   269   78   89   243   306   851           xDSL 180   798   798   225   63   74   202   266   805           xDSL 185   755   755   185   51   60   162   224   764                  
 
         [0091]    [0091]                                                                                                             TABLE 8                           ADSL2 Downstream Channel performance                downstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    ADSL2   xDSL 10   298   298   305   328   326   307   162   170           xDSL 11   0   0   0   0   0   0   0   0           xDSL 12   0   0   0   0   0   0   0   0           xDSL 13   0   0   0   0   0   0   0   0           xDSL 160   300   300   303   323   321   303   88   91           xDSL 165   201   201   203   224   224   207   43   49           xDSL 170   125   125   113   141   140   123   8   13           xDSL 175   59   66   57   74   74   63   0   0           xDSL 180   0   8   12   17   17   12   0   0           xDSL 185   0   0   0   0   0   0   0   0                    
         [0092]    Tables 9 and 10 display the results of the Modified OJ-074. These results may be taken as references for LDSL.  
                                                                                                             TABLE 9                           M OJ-074 Upstream Channel Performance Results                upstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    M OJ-074   xDSL 10   839   841   488   300   315   458   510   844           xDSL 11   667   667   312   144   159   283   332   669           xDSL 12   622   623   270   111   124   242   289   624           xDSL 13   496   496   157   59   69   136   176   497           xDSL 160   709   710   353   174   191   324   374   711           xDSL 165   675   675   319   145   161   291   340   677           xDSL 170   641   641   287   120   134   259   307   642           xDSL 175   606   606   255   101   110   227   275   608           xDSL 180   572   572   224   80   92   198   243   573           xDSL 185   537   537   195   66   76   169   212   539                  
 
         [0093]    [0093]                                                                                                             TABLE 10                           M OJ-074 Upstream Channel Performance Results                downstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    M OJ-074   xDSL 10   2396   1659   1784   2023   1991   1616   224   436           xDSL 11   997   407   431   861   892   358   0   79           xDSL 12   1202   643   622   974   969   546   0   48           xDSL 13   855   398   449   696   776   350   0   52           xDSL 160   2048   1333   1413   1752   1725   1268   150   331           xDSL 165   1788   1086   1179   1527   1518   1027   92   261           xDSL 170   1553   875   933   1326   1332   809   53   205           xDSL 175   1343   754   755   1145   1163   648   25   152           xDSL 180   1147   633   694   985   1011   579   4   111           xDSL 185   978   529   608   840   872   500   0   76                    
         [0094]    Tables 11 and 12 give the results of NON EC Smart LDSL system.  
                                                                                                             TABLE 11                           NON EC Smart LDSL Upstream Channel Performance Results                upstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    NON EC   xDSL 10   839   841   488   310   324   458   510   851       SMART   xDSL 11   667   667   312   179   196   283   332   673           xDSL 12   622   623   270   146   157   242   289   628           xDSL 13   496   496   176   102   110   142   176   500           xDSL 160   709   710   353   206   219   324   374   716           xDSL 165   675   675   319   182   195   291   340   681           xDSL 170   641   641   287   152   168   259   307   646           xDSL 175   606   606   255   136   145   227   275   611           xDSL 180   572   572   226   122   130   198   243   577           xDSL 185   537   537   200   108   116   169   212   542                  
 
         [0095]    [0095]                                                                                                             TABLE 12                           NON EC Smart LDSL Downstream Channel Performance Results                downstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    NON EC   xDSL 10   2615   1711   1946   2148   2169   1679   224   572       SMART   xDSL 11   1060   407   445   902   958   358   0   135           xDSL 12   1265   643   634   998   1025   546   0   105           xDSL 13   885   398   449   705   816   350   0   79           xDSL 160   2156   1333   1466   1797   1816   1268   150   429           xDSL 165   1885   1086   1222   1572   1604   1027   92   349           xDSL 170   1639   875   967   1370   1413   809   53   278           xDSL 175   1418   754   782   1187   1237   648   25   220           xDSL 180   1213   633   720   1025   1079   579   4   169           xDSL 185   1034   529   629   877   932   500   0   126                    
         [0096]    Tables 13 and 14 give the selected Upstream and Downstream masks by the smart system. These tables confirm that, for this embodiment, a single mask can&#39;t handle all the noise scenarios and all the loops.  
                                                                                                             TABLE 13                           NON EC Smart LDSL: Upstream Selection Table                Upstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    selection   xDSL 10   3   3   3   2   2   3   3   3       index   xDSL 11   3   3   3   2   2   3   3   3           xDSL 12   3   3   3   1   2   3   3   3           xDSL 13   3   3   2   1   1   2   2   3           xDSL 160   3   3   3   2   2   3   3   3           xDSL 165   3   3   3   2   2   3   3   3           xDSL 170   3   3   3   2   2   3   3   3           xDSL 175   3   3   3   1   1   3   3   3           xDSL 180   3   3   2   1   1   3   3   3           xDSL 185   3   3   2   1   1   3   3   3                                          
 
         [0097]    [0097]                                                                                                             TABLE 14                           NON EC Smart LDSL: Downstream Selection Table                Downstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    selection   xDSL 10   1   1   1   1   1   1   2   1       index   xDSL 11   1   2   1   1   1   2   1   1           xDSL 12   1   2   1   1   1   2   1   1           xDSL 13   1   2   2   1   1   2   1   1           xDSL 160   1   2   1   1   1   2   2   1           xDSL 165   1   2   1   1   1   2   2   1           xDSL 170   1   2   1   1   1   2   2   1           xDSL 175   1   2   1   1   1   2   2   1           xDSL 180   1   2   1   1   1   2   2   1           xDSL 185   1   2   1   1   1   2   1   1                                    
         [0098]    Tables 15 and 16 provide the performance improvement inherent to the NON EC Smart LDSL versus M OJ-074. As can be seen from the tables, this embodiment of a smart system performs better than the system disclosed in M OJ-074. This embodiment of a smart system compensates for the M OJ-074 Upstream channel weaknesses in the presence of SHDSL and HDSL.  
                                                                                   TABLE 15                           (NON EC SMART LDSL US rate - M OJ074 US rate)       upstream difference with M OJ-074            case 1                                   Self   case 2   case 3   case 4   case 5   case 6   case 7       Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    0   0   0   10   9   0   0   7       0   0   0   35   37   0   0   4       0   0   0   35   33   0   0   4       0   0   19   43   41   6   0   3       0   0   0   32   28   0   0   5       0   0   0   37   34   0   0   4       0   0   0   32   34   0   0   4       0   0   0   35   35   0   0   3       0   0   2   42   38   0   0   4       0   0   5   42   40   0   0   3                  
 
         [0099]    [0099]                                                                                   TABLE 16                           (NON EC SMART LDSL DS rate - M OJ074 DS rate)       downstream difference with M OJ-074            case 1                                   Self   case 2   case 3   case 4   case 5   case 6   case 7       Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    219   52   162   125   178   63   0   136       63   0   14   41   66   0   0   56       63   0   12   24   56   0   0   57       30   0   0   9   40   0   0   27       108   0   53   45   91   0   0   98       97   0   43   45   86   0   0   88       86   0   34   44   81   0   0   73       75   0   27   42   74   0   0   68       66   0   26   40   68   0   0   58       56   0   21   37   60   0   0   50                    
         [0100]    [0100]FIGS. 4-9 show bar chart performance plots of ADSL2, non-EC smart LDSL and the system disclosed in M OJ-074, for the above described noise cases.  
         [0101]    EC Smart LDSL system  
         [0102]    Definition  
         [0103]    As described above, a first exemplary smart system may make use of U1, U2, U3 and D1, D2, D3. In accordance with the features of all these masks, an Echo canceller may be advantageous when D2 is used. A second exemplary smart system may be identified as the EC Smart LDSL. For this embodiment, the Smart LDSL system may have the capability to analyze a priori the cross talk/physical layer conditions for all the Smart LDSL modems located in the same area. In addition the system may detect the same type of cross talks/impairments and, therefore, the worst case self NEXT due to the Downstream mask D2 may only apply when this mask is used.  
         [0104]    EC Smart LDSL: Simulation results  
                                                                                                             TABLE 17                           EC Smart LDSL Upstream Channel Performance Results                upstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    EC   xDSL 10   839   841   488   310   324   458   456   423       SMART   xDSL 11   667   667   312   179   196   283   280   253       LDSL   xDSL 12   622   623   270   146   157   242   239   214           xDSL 13   496   496   176   102   110   142   135   130           xDSL 160   709   710   353   206   219   324   321   291           xDSL 165   675   675   319   182   195   291   288   259           xDSL 170   641   641   287   152   168   259   256   229           xDSL 175   606   606   255   136   145   227   225   200           xDSL 180   572   572   226   122   130   198   195   168           xDSL 185   537   537   200   108   116   169   166   139                  
 
         [0105]    [0105]                                                                                                             TABLE 18                           EC Smart LDSL Downstream Channel Performance Results                Downstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    EC   xDSL 10   2615   1711   1946   2148   2169   1679   381   719       SMART   xDSL 11   1060   407   445   902   958   358   54   193       LDSL   xDSL 12   1265   643   634   998   1025   546   38   140           xDSL 13   885   398   449   705   816   350   18   80           xDSL 160   2156   1333   1466   1797   1816   1268   216   476           xDSL 165   1885   1086   1222   1572   1604   1027   140   388           xDSL 170   1639   875   967   1370   1413   809   86   308           xDSL 175   1418   754   782   1187   1237   648   62   237           xDSL 180   1213   633   720   1025   1079   579   28   181           xDSL 185   1034   529   629   877   932   500   20   127                    
         [0106]    [0106]                                                                                                             TABLE 19                           EC Smart LDSL: Upstream Selection Table                Upstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    EC   xDSL 10   3   3   3   2   2   3   3   3       SMART   xDSL 11   3   3   3   2   2   3   3   3       LDSL   xDSL 12   3   3   3   1   2   3   3   3           xDSL 13   3   3   2   1   1   2   2   1           xDSL 160   3   3   3   2   2   3   3   3           xDSL 165   3   3   3   2   2   3   3   3           xDSL 170   3   3   3   2   2   3   3   3           xDSL 175   3   3   3   1   1   3   3   3           xDSL 180   3   3   2   1   1   3   3   2           xDSL 185   3   3   2   1   1   3   3   2                                            
         [0107]    [0107]                                                                                                             TABLE 20                           EC Smart LDSL: Downstream Selection Table                Downstream                    case 1   case 2   case 3   case 4   case 5   case 6   case 7                   Self Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    EC   xDSL 10   2   2   2   2   2   2   1   1       SMART   xDSL 11   2   3   2   2   2   3   1   1       LDSL   xDSL 12   2   3   2   2   2   3   1   1           xDSL 13   2   3   3   2   2   3   1   1           xDSL 160   2   3   2   2   2   3   1   1           xDSL 165   2   3   2   2   2   3   1   1           xDSL 170   2   3   2   2   2   3   1   1           xDSL 175   2   3   2   2   2   3   1   1           xDSL 180   2   3   2   2   2   3   1   1           xDSL 185   2   3   2   2   2   3   1   1                                    
         [0108]    [0108]                                                                                   TABLE 21                           (EC SMART LDSL US rate - M OJ074 US rate)       upstream difference with M OJ-074            case 1                                   Self   case 2   case 3   case 4   case 5   case 6   case 7       Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    0   0   0   10   9   0   −54   −421       0   0   0   35   37   0   −52   −416       0   0   0   35   33   0   −50   −410       0   0   19   43   41   6   −41   −367       0   0   0   32   28   0   −53   −420       0   0   0   37   34   0   −52   −418       0   0   0   32   34   0   −51   −413       0   0   0   35   35   0   −50   −408       0   0   2   42   38   0   −48   −405       0   0   5   42   40   0   −46   −400                    
         [0109]    [0109]                                                                                   TABLE 22                           (EC SMART LDSL DS rate - M OJ074 DS rate)       downstream difference with M OJ-074            case 1                                   Self   case 2   case 3   case 4   case 5   case 6   case 7       Next   ADSL   ISDN   SHDSL   HDSL   MIX   TIA   T1                    219   52   162   125   178   63   157   283       63   0   14   41   66   0   54   114       63   0   12   24   56   0   38   92       30   0   0   9   40   0   18   28       108   0   53   45   91   0   66   145       97   0   43   45   86   0   48   127       86   0   34   44   81   0   33   103       75   0   27   42   74   0   37   85       66   0   26   40   68   0   24   70       56   0   21   37   60   0   20   51                    
         [0110]    [0110]FIGS. 20-35 show bar chart performance plots of ADSL2, EC smart LDSL and the system disclosed in M OJ-074, for the above described noise cases.  
         [0111]    Smart DSL Implementation based on ITU-T Recommendation G.992.3  
         [0112]    Two steps  
         [0113]    Deciding to access one of the mask amongst all the possible choices offered by a smart DSL platform may be facilitated by using a two step process in the following order:  
         [0114]    (1) Masks Choice based on Performance/Physical layer status criterion: Smart functionality; and (2) Protocol to activate one particular mask based on CP/CO capabilities.  
         [0115]    Step (1): Mask Choice based on Performance/Physical layer Status: Smart Functionality.  
         [0116]    [0116]FIG. 36 displays the organizational chart that describes the two selection modes inherent to smart DSL: manual or automatic.  
         [0117]    The automatic selection may be completed in two different ways: by making use of the Line Probing capabilities of G.992.3 (LP Option) or by trying different masks up to the training and choosing at the end the best (Many Tests Option). FIG. 37 gives the state diagram of the two approaches to automatically select a pair of mask for a smart DSL platform.  
         [0118]    The LP option needs to complete the right loop of operations in FIG. 37 one time only. The Many tests option requires to complete the left loop of operations in FIG. 37 as many times as the number of available possibilities.  
         [0119]    Step 2: Protocol to activate one mask based on CO/CP capabilities.  
         [0120]    This section discloses three protocol examples to activate one mask based on CO/CP capabilities.  
         [0121]    Option 1: CP decides  
         [0122]    [0122]FIG. 38 describes the “CP decides” which mask is to be used sequence, based on G.992.3. CLR and CL allow CP and CO to signify their list of capabilities.  
         [0123]    Option 2: CO decides  
         [0124]    [0124]FIG. 39 describes the “CO decides” which mask is to be used sequence, based on G.992.3, after being requested by the CP to do so. CLR and CL allow CP and CO to signify their list of capabilities.  
         [0125]    Option 3: CP is overruled by CO  
         [0126]    [0126]FIG. 40 describes the “CO overrules CP” about which mask is to be used sequence, based on G.992.3, after CP has mentioned which mask is to be used. CLR and CL allow CP and CO to signify their list of capabilities.