U.S. patent application number 10/316155 was filed with the patent office on 2003-06-12 for system and method for reducing noise induced by digital subscriber line (dsl) systems into services that are concurrently deployed on a communication line.
Invention is credited to Duvaut, Patrick, Langberg, Ehud, Moreno, Oliver, Pierrugues, Laurent, Scholtz, William.
Application Number | 20030108095 10/316155 |
Document ID | / |
Family ID | 27575406 |
Filed Date | 2003-06-12 |
United States Patent
Application |
20030108095 |
Kind Code |
A1 |
Duvaut, Patrick ; et
al. |
June 12, 2003 |
System and method for reducing noise induced by digital subscriber
line (DSL) systems into services that are concurrently deployed on
a communication line
Abstract
Systems and methods are presented for reducing noise induced by
digital subscriber line (DSL) systems into services that are
concurrently deployed on a communication line. In the disclosed
technique, a power level of a discrete multi-tone (DMT) sub-carrier
is adaptively calculated from a signal that is received from a
communication line. The signal has information indicative of line
conditions, which are further indicative of services deployed on
the communication line.
Inventors: |
Duvaut, Patrick; (Belford,
NJ) ; Langberg, Ehud; (Wayside, NJ) ; Scholtz,
William; (Red Bank, NJ) ; Pierrugues, Laurent;
(Rahway, NJ) ; Moreno, Oliver; (Eatontown,
NJ) |
Correspondence
Address: |
THOMAS, KAYDEN, HORSTEMEYER & RISLEY, LLP
100 GALLERIA PARKWAY, NW
STE 1750
ATLANTA
GA
30339-5948
US
|
Family ID: |
27575406 |
Appl. No.: |
10/316155 |
Filed: |
December 10, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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60338939 |
Dec 10, 2001 |
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60341654 |
Dec 17, 2001 |
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60346809 |
Jan 7, 2002 |
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60348575 |
Jan 14, 2002 |
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60350552 |
Jan 22, 2002 |
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60353880 |
Feb 2, 2002 |
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60354888 |
Feb 6, 2002 |
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60355117 |
Feb 8, 2002 |
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Current U.S.
Class: |
375/222 |
Current CPC
Class: |
H04Q 2213/13209
20130101; H04L 12/66 20130101; H04L 47/10 20130101; H04M 11/062
20130101; H04Q 2213/13191 20130101; H04Q 2213/13389 20130101; H04Q
2213/13176 20130101; H04L 27/2647 20130101; H04L 5/0044 20130101;
H04Q 2213/1319 20130101; H04L 27/2608 20130101; H04Q 2213/13039
20130101; H04L 47/38 20130101 |
Class at
Publication: |
375/222 |
International
Class: |
H04B 001/38; H04L
005/16 |
Claims
The claims are:
1. A discrete multi-tone (DMT) modulated communication system
comprising: a receiver configured to receive signals from a
communication line, the signals having information indicative of
line conditions; and logic configured to adaptively calculate a
power level of a DMT sub-carrier in response to received signals
from the communication line.
2. The system of claim 1. wherein the logic configured to
adaptively calculate the power level of the DMT sub-carrier
comprises logic configured to determine a signal-to-noise ratio
(SNR) of the communication line.
3. The system of claim 1 wherein the logic configured to adaptively
calculate the power level of the DMT sub-carrier comprises logic
configured to determine line attenuation information of the
communication line.
4. The system of claim 1, wherein the logic configured to
adaptively calculate the power level of the DMT stub-carrier
comprises logic configured to determine information related to
usable sub-carriers in the DMT modulated system.
5. The system of claim 1, further comprising logic configured to
load the DMT sub-carrier with data, the DMT sub-carrier being
loaded as a function of the adaptively-determined power level.
6. A discrete multi-tone (DMT) modulated digital subscriber line
(DSL) system comprising: an adaptively-filtered power spectral
density (PSD) mask having an attenuated portion, the attenuated
portion configured to adaptively change in response to line
characteristics; and logic configured to load DMT sub-carriers with
data, the DMT sub-carriers, being loaded according to the
adaptively-filtered PSD mask.
7. The system of claim 6, further comprising: a receiver configured
to receive signals from a communication line, the signals having
information indicative line conditions; and logic configured to
adaptively determine the services deployed on the communication
line from the received signals.
8. The system of claim 7, wherein the attenuated portion is further
configured to change in response to the adaptively determined
services deployed on the communication line.
9. The system of claim 6, wherein the attenuated portion has a
variable power over a fixed frequency range.
10. The system of claim 6, wherein the attenuated portion has a
variable power over a variable frequency range.
11. A system comprising: an adaptive filter having an attenuation
bandwidth, the adaptive filter configured to adaptively attenuate
power within a portion of a power spectral density (PSD) mask to
generate an adaptively-filtered PSD mask; and logic configured to
allocate power to sub-carriers in a discrete multi-tone (DMT)
modulated communication system, the power being allocated according
to the adaptively-filtered PSD mask.
12. The system of claim 11, wherein the adaptive filter is
configured to selectively provide a fixed attenuation over a fixed
frequency range.
13. The system of claim 12, wherein the fixed attenuation over the
fixed frequency range is approximately -8 dB between approximately
100 kHz and approximately 200 kHz.
14. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately 55 ( - 97 5 + 17 8 .times.
log 2 ( f 4 ) )dBm/Hz between approximately 4 kHz and approximately
26 kHz; approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 147 kHz; approximately -41.5 dBm/Hz between
approximately 147 kHz and approximately 164 kHz; approximately
-36.5 dBm/Hz between approximately 164 kHz and approximately 1104
kHz; approximately 56 ( - 36.5 - 36 .times. log 2 ( f 1104 )
)between approximately 1104 kHz and approximately 3093 kHz; and
approximately -90 dBm/Hz above approximately 3093 kHz.
15. The system of claim 12, wherein the fixed attenuation over the
fixed frequency range is: approximately 57 ( - 12 - 32 84 .times.
log 2 ( f 99 ) )between approximately 99 kHz and approximately 151
kHz; and approximately -32 dBm/Hz between approximately 151 kHz and
approximately 164 kHz.
16. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately 58 ( - 97 5 + 17 8 .times.
log 2 ( f 4 ) )dBm/Hz between approximately 4 kHz and approximately
26 kHz; approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; approximately 59 ( - 49.5 - 115 8 .times.
log 2 ( f 121 ) )dBm/Hz between approximately 121 kHz and
approximately 151 kHz; approximately -86.5 dBm/Hz between
approximately 151 kHz and approximately 164 kHz; approximately
-36.5 dBm/Hz between approximately 164 kHz and approximately 1104
kHz; approximately 60 ( - 36.5 - 36 .times. log 2 ( f 1104 )
)between approximately 1104 kHz and approximately 3093 kHz; and
approximately -90 dBm/Hz above approximately 3093 kHz.
17. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately 61 ( - 97.5 + 17.8 .times.
log 2 ( f 4 ) )dBm/Hz between approximately 4 kHz and approximately
26 kHz; approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; approximately 62 ( - 49.5 - 78.24 .times.
log 2 ( f 121 ) )dBm/Hz between approximately (121 kHz and
approximately 151 kHz; approximately -74.5 dBm/Hz between
approximately 151 kHz and approximately 164 kHz; approximately
-36.5 dBm/Hz between approximately 164 kHz and approximately 1104
kHz; approximately 63 ( - 36 5 - 36 .times. log 2 ( f 1104 )
)between approximately 1104 kHz and approximately 3093 kHz; and
approximately -90 dBm/Hz above approximately 3093 kHz.
18. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately -94.5 dBm/Hz between
approximately 4 kHz and approximately 31 kHz; approximately 64 ( -
94 5 + 10 88 .times. log 2 ( f 31 ) )dBm/Hz between approximately
31 kHz and approximately 104 kHz; approximately 65 ( - 75.5 + 96 54
.times. log 2 ( f 104 ) )dBm/Hz between approximately 104 kHz and
approximately 134 kHz; approximately 66 ( - 40 2 + 9 6 .times. log
2 ( f 134 ) )dBm/Hz between approximately 134 kHz and approximately
175 kHz; approximately -36.5 dBm/Hz between approximately 175 kHz
and approximately 1104 kHz; approximately 67 ( - 36.5 - 36 .times.
log 2 ( f 1104 ) )between approximately 1104 kHz and approximately
3093 kHz; and approximately -90.5 dBm/Hz above approximately 3093
kHz.
19. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately -94.5 dBm/Hz between
approximately 4 kHz and approximately 24 kHz; approximately 68 ( -
80 + 18 42 .times. log 2 ( f 24 ) )dBm/Hz between approximately 24
kHz and approximately 43 (kHz; approximately 69 ( - 64 5 + 18
.times. log 2 ( f 43 ) )dBm/Hz between approximately 43 kHz and
approximately 74 kHz; approximately 70 ( - 50.4 + 14.24 .times. log
2 ( f 74 ) )dBm/Hz between approximately 74 kHz and approximately
121 kHz; approximately 71 ( - 403 + 761 .times. log 2 ( f 121 )
)dBm/Hz between approximately 121 kHz and approximately 171 kHz;
approximately -36.5 dBm/Hz between approximately 171 kHz and
approximately 1104 kHz; approximately 72 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )between approximately 1104 kHz and approximately 3093
kHz; and approximately -90.5 dBm/Hz above approximately 3093
kHz.
20. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately -86.5 dBm/Hz between
approximately 4 kHz and approximately 10 kHz; approximately 73 ( -
86.5 + 258 .times. log 2 ( f 10 ) )dBm/Hz between approximately 10
kHz and approximately 27 kHz; approximately 74 ( - 495 + 946
.times. log 2 ( f 27 ) )dBm/Hz between approximately 27 kHz and
approximately 70 kHz approximately -36.5 dBm/Hz between
approximately 70 kHz and approximately 1104 kHz; approximately 75 (
- 365 - 36 .times. log 2 ( f 1104 ) )between approximately 1104 kHz
and approximately 3093 kHz; and approximately -90.5 dBm/Hz above
approximately 3093 kHz.
21. The system of claim 12, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
belongs approximately 4 kHz; approximately 76 ( - 97.5 + 11 .times.
log 2 ( f 4 ) )dBm/Hz between approximately 4 kHz and approximately
50 kHz; approximately 77 ( - 57.5 + 157 .times. log 2 ( f 50 )
)dBm/Hz between approximately 50 kHz and approximately 126 kHz;
approximately -36.5 dBm/Hz between approximately 164 kHz and
approximately 1104 kHz; approximately 78 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )between approximately 1104 kHz and approximately 3093
kHz; and approximately -90.5 dBm/Hz above approximately 3093
kHz.
22. The system of claim 12,. wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately -94.5 dBm/Hz between
approximately 4 kHz and approximately 32 kHz; approximately 79 ( -
945 + 2065 .times. log 2 ( f 32 ) )dBm/Hz between approximately 32
kHz and approximately 109 kHz; approximately 80 ( - 58 + 58 .times.
log 2 ( f 109 ) )dBm/Hz between approximately 109 kHz and
approximately 138 kHz; approximately 81 ( - 38 3 + 3 36 .times. log
2 ( f 138 ) ) dBm/Hz between approximately 138 kHz and
approximately 200 kHz; approximately -36.5 dBm/Hz between
approximately 200 kHz and approximately 1104 kHz; approximately 82
( - 36 5 - 36 .times. log 2 ( f 1104 ) )between approximately 1104
kHz and approximately 3093 kHz; and approximately -90.5 dBm/Hz
above approximately 3093 kHz.
23. The system of claim 11, wherein the adaptive filter is
configured to provide a variable attenuation over a fixed frequency
range.
24. The system of claim 23, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; approximately 83 ( - 97.5 + 17.8 .times.
log 2 ( f 4 ) )dBm/Hz between approximately 4 kHz and approximately
26 kHz: approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 147 kHz; an adaptively varying, power level between
approximately 147 kHz and approximately 164 kHz; approximately
-36.5 dBm/Hz between approximately 164 kHz and approximately 1104
kHz; approximately 84 ( - 36 5 - 36 .times. log 2 ( f 1104 )
)between approximately 1104 kHz and approximately 3093 kHz; and
approximately -90 dBm/Hz above approximately 3093 kHz.
25. The system of claim 23, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately 97.5 dBm/Hz below
approximately 4 kHz; an adaptively varying power level between
approximately 4 kHz and approximately 26 kHz; approximately -36.5
dBm/Hz between approximately 26 kHz and approximately 147 kHz;
approximately -41.5 dBm/Hz between approximately 147 kHz and
approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 85
( - 36 5 - 36 .times. log 2 ( f 1104 ) )between approximately 1104
kHz and approximately 3093 kHz; and approximately -90 dBm/Hz above
approximately 3093 kHz.
26. The system of claim 23, wherein the adaptively-filtered PSD
mask is defined by power levels of: approximately -97.5 dBm/Hz
below approximately 4 kHz; an adaptively varying power level
between approximately 4 kHz and approximately 26 kHz; approximately
-36.5 dBm/Hz between approximately 26 kHz and approximately 147
kHz; an adaptively varying power level between approximately 147
kHz and approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 86
( - 36 5 - 36 .times. log 2 ( f 1104 ) )between approximately 1104
kHz and approximately 3093 kHz; and approximately -90 dBm/Hz above
approximately 3093 kHz.
27. The system of claim 24, wherein the adaptively varying power
level ranges from approximately 0 dBm/Hz to approximately -12
dBm/Hz.
28. The system of claim 11, wherein the adaptive filter is
configured to provide a-fixed attenuation over a variable frequency
range.
29. The system of claim 28, wherein the fixed attenuation is
approximately -8 dBm/Hz.
30. The system of claim 28, wherein the fixed attenuation is
approximately -12 dBm/Hz.
31. The system of claim 11, wherein the adaptive filter is
configured to provide a variable attenuation over a variable
frequency range.
32. In a discrete multi-tone (DMT) modulated communication system,
a method comprising: receiving a signal from a communication line,
the signal having information indicative of line conditions; and
adaptively determining a power level of a DMT sub-carrier in
response to receiving the signal from the communication line.
33. The method of claim 32, further comprising: loading the DMT
sub-carrier with data, the DMT sub-carrier being loaded according
to the adaptively determined power level.
34. The method of claim 32, further comprising: adaptively
attenuating power within a portion of a power spectral density
(PSD) mask.
35. The method of claim 34, wherein the adaptively attenuating
power within the portion of the PSD mask comprises: variably
attenuating a fixed bandwidth.
36. The method of claim 35, wherein the variably attenuating a
fixed bandwidth comprises: variably attenuating DMT sub-carriers
between approximately 100 kHz and approximately 200 kHz
37. The method of claim 35, wherein the variably attenuating a
fixed bandwidth comprises: variably attenuating DMT sub-carriers
between approximately 4 kHz and approximately 26 kHz
38. The method of claim 35, wherein the variably attenuating a
fixed bandwidth comprises: variably attenuating DMT sub-carriers
between approximately 121 kHz and approximately 164 kHz
39. The method of claim 34, wherein the adaptively attenuating
power within the portion of the PSD mask comprises: variably
attenuating a variable bandwidth.
40. In a discrete multi-tone (DMT) modulated communication system,
a system comprising: means for receiving a signal from a
communication line, the signal having information indicative of
line conditions; and means for adaptively determining a power level
of a DMT sub-carrier in response to receiving the signal from the
communication line.
41. The system of claim 40, further comprising: means for loading
the DMT sub-carrier with data, the DMT sub-carrier being loaded
according to the adaptively determined power level.
42. The system of claim 40, further comprising: means for
adaptively attenuation power within a portion of a power spectral
density (PSD) mask.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. provisional
patent application serial Nos. 60/338,939, dated Dec. 10, 2001;
60/341,654, dated Dec. 16, 2001; 60/346,809, dated Jan. 7, 2002;
60/348,575, dated Jan. 14, 2002; 60/350,552, dated Jan. 22, 2002;
60/353,880, dated Feb. 2, 2002; 60/354,888, dated Feb. 6, 2002; and
60/355,117, dated Feb. 8, 2002. These U. S. provisional patent
applications are incorporated herein by reference as if set forth
in their entireties.
[0002] Co-pending U.S. patent application Ser. Nos. 060706-1550 (EL
891429200 US) and 060706-1680 (EL 891429227 US), both mailed on
Dec. 10, 2002, are also incorporated herein by reference as if set
forth in their entireties.
FIELD OF INVENTION
[0003] The present invention relates generally to data
communication and, more particularly, to systems and methods for
reducing noise induced by digital subscriber line (DSL) systems
into services that are concurrently deployed on a communication
line.
BACKGROUND
[0004] Industries related to modern communication systems have
experienced a tremendous growth due to the increasing popularity of
the Internet. Digital subscriber line (DSL) technology is one
technology that has developed in recent years in response to the
demand for high-speed Internet access. DSL technology uses a
communication line of a pre-existing telephone system as the
backbone for the DSL lines. Thus, both plain old telephone systems
(POTS) and DSL systems share a common line for DSL-compatible
customer premises. Similarly, other services such as time
compression multiplexing (TCM) integrated services digital network
(ISDN) can also share a common line with DSL and POTS.
[0005] POTS services and DSL services are deployed on
non-overlapping portions of available bandwidth on the
communication line. Thus, there is very little concern of
cross-talk or other interference between POTS services and DSL
services. However, DSL and TCM-ISDN often share a portion of the
available bandwidth, thereby making DSL services susceptible to
cross-talk from TCM-ISDN services, and vice versa.
[0006] To compound problems even further, system requirements
(e.g., the degree of permissible disruption of TCM-ISDN service
caused by DSL service) may vary greatly from country to country.
For example, Japan may have a greater limitation than the United
States on how much disruption is tolerable between
concurrently-deployed services on the same line. Thus, acceptable
power levels for signal transmission in the United States may be
unacceptable for signal transmission in Japan.
[0007] Certain standards committees, such as the International
Telecommunication Union-Telecommunication Standardization Sector
(ITU-T), have provided standards documents for deployment of DSL,
such as G.992.2, "Splitterless Asymmetric Digital Subscriber Line
(ADSL) Transceivers" (hereinafter "ITU-T G.992.2"), published in
June of 1999. These standards documents provide static power
spectral density (PSD) masks that limit the amount of power
allocated to the DSL bandwidth, thereby limiting the amount of
cross-talk induced by the DSL system on other services concurrently
deployed on the same line. For example, FIGS. 1 through 4 show
several static PSD masks defined by the ITU.
[0008] FIG. 1 is a diagram showing a static PSD mask for an
asymmetric digital subscriber line transceiver unit at a central
office (ATU-C) as defined by the ITU-T in Annex A of G.992.1
"Asymmetric Digital Subscriber Line (ADSL) Transceivers"
(hereinafter "ITU-T G.992.1") and G.992.2. As shown in FIG. 1, the
static PSD mask is defined by a -97.5 dBm/Hz peak power in the POTS
bandwidth; approximately 1 ( - 92.5 + 21 .times. log 2 ( f 4 )
)
[0009] dBm/Hz between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 1104 kHz; approximately 2 ( - 36.5 - 36 .times. log 2
( f 1104 ) )
[0010] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz.
[0011] FIG. 2 is a diagram showing a static PSD mask for reduced
near-end cross talk (NEXT) for an ATU-C as defined by Annex A of
G.992.1 and G.992.2. As shown in FIG. 2, the static PSD mask is
defined by approximately -97.5 dBm/Hz below approximately 4 kHz;
approximately 3 ( - 92.5 + 4.63 .times. log 2 ( f 4 ) )
[0012] dBm/Hz between approximately 4 kHz and approximately 80 kHz;
approximately 4 ( - 72.5 + 36 .times. log 2 ( f 80 ) )
[0013] dBm/Hz between approximately 80 kHz and approximately 138
kHz; approximately -36.5 dBm/Hz between approximately 138 kHz and
approximately 1104 kHz; approximately 5 ( - 36.5 - 36 .times. log 2
( f 1104 ) )
[0014] between approximately 1104 kHz and approximately 3093 kHz;
approximately -90 dBm/Hz between approximately 3093 kHz and
approximately 4545 kHz; and approximately -50 dBm/Hz power in any 1
MHz sliding window between approximately 4545 kHz and approximately
11040 kHz.
[0015] FIG. 3 is a diagram showing a static PSD mask for
ADSL/Integrated Service Digital Network (ISDN) with
2-Binary-1-Quaternary (2B1Q) line coding as defined by Annex B of
G.992.1 and G.992.2. As shown in FIG. 3, the static PSD mask is
defined by a power level of approximately -90 dBm/Hz below
approximately 50 kHz; approximately 6 ( - 90 + 12 .times. log 2 ( f
70 ) )
[0016] dBm/Hz between approximately 50 kHz and approximately 80
kHz; low-pass and high-pass filter-design-dependent power level
between approximately 80 kHz and approximately 138 kHz;
approximately -36.5 dBm/Hz between approximately 138 kHz and
approximately 1104 kHz; approximately 7 ( - 36.5 - 36 .times. log 2
( f 1104 ) )
[0017] between approximately 1104 kHz and approximately 3093 kHz;
approximately -90 dBm/Hz between approximately 3093 kHz and
approximately 4545 kHz; and approximately -50 dBm/Hz power in any 1
MHz sliding window between approximately 4545 kHz and approximately
11040 kHz.
[0018] FIG. 4 is a diagram showing a static PSD mask for ADSL/ISDN
with 4B3T line coding as defined by Annex B of G.992.1 and G.992.2.
As shown in FIG. 4, the static PSD mask is defined by a power level
of approximately -90 dBm/Hz below approximately 70 kHz;
approximately 8 ( - 90 + 12 .times. log 2 ( f 70 ) )
[0019] dBm/Hz between approximately 70 kHz and approximately 90
kHz; low-pass and high-pass filter-design-dependent power level
between approximately 90 kHz and approximately 138 kHz;
approximately -36.5 dBm/Hz between approximately 138 kHz and
approximately 1104 kHz; approximately 9 ( - 36.5 - 36 .times. log 2
( f 1104 ) )
[0020] between approximately 1104 kHz and approximately 3093 kHz;
approximately -90 dBm/Hz between approximately 3093 kHz and
approximately 4545 kHz; and approximately -50 dBm/Hz power in any 1
MHz sliding window between approximately 4545 kHz and approximately
11040 kHz.
[0021] The various static PSD masks of FIGS. 1 through 4 are
configured for certain fixed line conditions. Thus, while the
static PSD masks shown in FIGS. 1 through 4 may result in
acceptable disruptions to TCM-ISDN services by the DSL services in
one environment, these static PSD masks may result in unacceptable
disruptions in other environments. Consequently, communication
devices that are standards-compliant in one environment may not
necessarily be standards-compliant in other environments.
[0022] Given the potential incompatibility of communication devices
in various environments, heretofore-unaddressed needs exist in the
industry.
SUMMARY
[0023] The present invention provides systems and methods for
reducing noise induced by digital subscriber line (DSL) systems
into services that are concurrently deployed on a communication
line.
[0024] Briefly described, in architecture, one embodiment of the
system comprises a receiver and logic configured to adaptively
calculate a power level of a discrete multi-tone (DMT) sub-carrier.
The receiver is configured to receive signals from a communication
line. The signals are indicative of line conditions, which may be
indicative of services deployed on the communication line. The
power level of the DMT sub-carrier may be adaptively calculated
from the signals received from the communication line.
[0025] Another embodiment of the system comprises an
adaptively-filtered power spectral density (PSD) mask and logic
configured to load DMT sub-carriers with data. The
adaptively-filtered PSD mask has an attenuated portion that
adaptively changes in response to line characteristics. The DMT
sub-carriers may be loaded in accordance with the
adaptively-filtered PSD-mask.
[0026] Yet another embodiment of the system comprises an adaptive
filter and logic configured to allocate power to sub-carriers in a
discrete multi-tone (DMT) modulated communication system. The
adaptive filter is configured to adaptively attenuate power within
a portion of a power spectral density (PSD) mask to generate an
adaptively-filtered PSD mask. The power allocated to the
sub-carriers may be allocated in accordance with the
adaptively-filtered PSD mask.
[0027] The present invention can also be embodied as methods for
reducing noise induced into services that are concurrently deployed
on a communication line. In this regard, one embodiment of the
method comprises the steps of receiving a signal from a
communication line and adaptively determining a power level of a
discrete multi-tone (DMT) sub-carrier in response to receiving the
signal from the communication line. In one embodiment, the signal
has information indicative of services deployed on the
communication line.
[0028] Other systems, methods, features, and advantages of the
present invention will be or become apparent to one with skill in
the art upon examination of the following drawings and detailed
description. It is intended that all such additional systems,
methods, features, and advantages be included within this
description, be within the scope of the present invention, and be
protected by the accompanying claims.
BRIEF DESCRIPTION OF THE DRAWINGS
[0029] Many aspects of the invention can be better understood with
reference to the following drawings. The components in the drawings
are not necessarily to scale, emphasis instead being placed upon
clearly illustrating the principles of the present invention.
Moreover, in the drawings, like reference numerals designate
corresponding parts throughout the several views.
[0030] FIG. 1 is a diagram showing a static power spectral density
(PSD) mask for an asymmetric digital subscriber line transceiver
unit at a central office (ATU-C) as defined by the
Telecommunication Standardization Sector (ITU-T) of the
International Telecommunication Union (ITU) in Annex A of G.992.1
"Asymmetric Digital Subscriber Line (ADSL) Transceivers"
(hereinafter "G.992.1 ") and G.992.2 "Splitterless Asymmetric
Digital Subscriber Line (ADSL) Transceivers" (hereinafter
"G.992.2").
[0031] FIG. 2 is a diagram showing a static PSD mask for reduced
near-end cross talk (NEXT) for an ATU-C as defined by Annex A of
G.992.1 and G.992.2.
[0032] FIG. 3 is a diagram showing a static PSD mask for
ADSL/Integrated Service Digital Network (ISDN) with
2-Binary-1-Quaternary (2B1Q) line coding as defined by Annex B of
G.992.1 and G.992.2.
[0033] FIG. 4 is a diagram showing a static PSD mask for ADSL/ISDN
with 4B3T line coding as defined by Annex B of G.992.1 and
G.992.2.
[0034] FIG. 5 is a block diagram showing an example ADSL
environment employing adaptively-filtered PSD masks.
[0035] FIG. 6 is a block diagram showing the ADSL modem of FIG. 5
in greater detail.
[0036] FIG. 7 is a block diagram showing logic components in the
ATU-C of FIG. 6, which are configured to generate the
adaptively-filtered PSD masks.
[0037] FIG. 8 is a diagram showing one embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0038] FIG. 9A is a diagram showing a transfer function associated
with one embodiment of the adaptive filter of FIG. 7, which has a
variable attenuation over a variable frequency range.
[0039] FIG. 9B is a diagram showing a transfer function associated
with one embodiment of the adaptive filter of FIG. 7, which has a
variable attenuation over a fixed frequency range.
[0040] FIG. 9C is a diagram showing a transfer function associated
with one embodiment of the adaptive filter of FIG. 7, which has a
specific attenuation over a fixed frequency range.
[0041] FIG. 10 is a diagram showing another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0042] FIG. 11 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0043] FIG. 12 is a diagram showing one embodiment of an
adaptively-filtered PSD mask having a variable attenuation
immediately above the plain old telephone system (POTS)
bandwidth.
[0044] FIG. 13 is a diagram showing one embodiment of an
adaptively-filtered PSD mask having a variable attenuation in a
frequency bandwidth affected by integrated services digital network
(ISDN) services.
[0045] FIG. 14 is a diagram showing one embodiment of an
adaptively-filtered PSD mask having a variable attenuation over a
variable frequency range.
[0046] FIG. 15A is a diagram showing a transfer function associated
with another embodiment of the adaptive filter of FIG. 7, which has
a variable attenuation over a variable frequency range.
[0047] FIG. 15B is a diagram showing a transfer function associated
with another embodiment of the adaptive filter of FIG. 7, which has
a variable attenuation over a fixed frequency range.
[0048] FIG. 15C is a diagram showing a transfer function associated
with another embodiment of the adaptive filter of FIG. 7, which has
a specific attenuation over a fixed frequency range.
[0049] FIG. 15D is a diagram showing a transfer function associated
with another embodiment of the adaptive filter of FIG. 7, which has
a specific attenuation over a fixed frequency range.
[0050] FIG. 16 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0051] FIG. 17 is a diagram showing one embodiment of an
adaptively-filtered PSD mask having a variable attenuation in a
frequency bandwidth affected by integrated services digital network
(ISDN) services.
[0052] FIG. 18 is a diagram showing another embodiment of an
adaptively-filtered PSD mask having a variable attenuation
immediately above the POTS bandwidth.
[0053] FIG. 19 is a diagram showing another embodiment of an
adaptively-filtered PSD mask having a variable attenuation in
several non-adjacent bandwidths.
[0054] FIG. 20 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0055] FIG. 21 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0056] FIG. 22 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0057] FIG. 23 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0058] FIG. 24 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
[0059] FIG. 25 is a flowchart showing one embodiment of a method
employing adaptively-filtered PSD masks.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0060] Having summarized various aspects of the present invention,
reference is now made in detail to the description of the
embodiments as illustrated in the drawings. While several
embodiments are described in connection with these drawings, there
is no intent to limit the invention to the embodiment or
embodiments disclosed herein. On the contrary, the intent is to
cover all alternatives, modifications, and equivalents included
within the spirit and scope of the invention as defined by the
appended claims.
[0061] In Japan, for example, feeder cables that radiate out of a
central office to various customer premises are predominantly
pulp-insulated. Each feeder cable typically has approximately 400
two-conductor pair wires, and a large portion of the pulp-insulated
two-conductor pair wires are used to service integrated services
digital network (ISDN) subscribers. Thus, when ADSL signals are
present, the pulp insulation causes ADSL signal attenuation at
higher frequencies, and adjacent ISDN signals cause significant
levels of cross-talk interference. The combination of attenuation
and cross-talk reduces ADSL performance. While Annex C of the
G.992.1 standard was developed to reduce adverse effects (e.g.,
attenuation and cross-talk), the static power spectral density
(PSD) masks often provide for sub-optimal data transmission.
[0062] FIGS. 5 through 25 illustrate various systems, methods, and
power spectral density (PSD) masks, which are configured to reduce
cross-talk between ADSL and ISDN while optimizing ADSL performance
for systems similar to those found in Japan. Each of the
embodiments maximizes downstream performance, balances upstream and
downstream signal ratios, and provides spectral compatibility
between ADSL and concurrently-deployed services (e.g., integrated
services digital network (ISDN), plain old telephone systems
(POTS), etc.). In maximizing downstream performance, the systems
and methods are configured to determine the optimum data capacity
given certain line conditions (e.g., signal-to-noise ratio (SNR),
line attenuation, etc.). The line conditions further provide
information that permit the allocation of bandwidths and time slots
for upstream and downstream signals, thereby balancing the upstream
and downstream signal ratios. Additionally, since the line
conditions provide information related to other
concurrently-deployed services on the line, the systems and methods
of FIGS. 5 through 25 also provide spectral compatibility between
ADSL and other concurrently-deployed services. The optimum
conditions are predetermined as a function of government
regulations, known or measured physical parameters, and other
factors that are well known in the art. The data transmission
parameters are then adjusted according to the predetermined optimum
conditions.
[0063] FIG. 5 is a block diagram showing an example asymmetric
digital subscriber line (ADSL) communication system 500 employing
adaptively-filtered PSD masks. Generally, the ADSL system is
implemented between a central office 510 and a customer premise
560. Communication between the two sites 510, 560 takes place over
a communication line 555 (also referred to as a local loop,
twisted-pair cable, two-conductor pair wire, or channel). The
central office 510 end of the communication line 555 is configured
to provide broadband services (e.g., video conferencing 515,
Internet 520, telephone services 525, movies on demand 530,
broadcast media 535, etc.), which are assembled via central office
ADSL modems 550 for transmission over the communication line 555.
The central office 510 assembles the signals from the broadband
services at an ADSL service rack 540, which comprises a digital
subscriber line access multiplexer (DSLAM) 545 and ADSL modems 550.
The central office 510 assembles the broadband services via the
DSLAM 545 for appropriate transformation and transmission by one or
more ADSL modems 550. Each of the ADSL modems 550 may be in
communication via a dedicated communication line 555 with a
suitably configured ADSL modem 580 at a customer premise 560.
[0064] As illustrated in FIG. 5, the DSLAM 545 and each of a
plurality of ADSL modems 550 may be assembled within an ADSL
service rack 540 within the central office 510. For simplicity of
illustration and explanation, the ADSL communication system 500
presented in FIG. 5 is shown with a single ADSL service rack 540
for communicating each of the broadband services to n ADSL modems
550. The ADSL service rack 540 may be configured to supply
conditioned resources necessary to support the operation of the n
ADSL modems 550. Those skilled in the art will appreciate the
scalability of the ADSL communication system 500 generally
presented in FIG. 5. For example, the central office 510 may be
configured with a plurality of Transmission Control
Protocol/Internet Protocol (TCP/IP) routers and Asynchronous
Transfer Mode (ATM) switches (not shown) that may distribute one or
more broadband service signals to a plurality of DSLAMs 545. In
turn, the plurality of DSLAMs 545 may further distribute the
broadband service signals to a plurality of remotely located ADSL
modems 580.
[0065] At the opposite end of the communication line 555, the
customer premise 560 may be configured with a compatible ADSL modem
580, which may be configured to process and distribute the multiple
broadband services to appropriate destination devices such as a
computer 570, a television 575, and digital telephones 590 as
illustrated. It is significant to note that that the customer
premise 560 may have plain old telephone systems (POTS) devices
such as a facsimile machine 565 and an analog (POTS) telephone 585
integrated on the communication line 555 along with the ADSL modem
580. It is also feasible that the customer premise 560 may be
replaced in some applications by another central office 510 or an
ADSL repeater, where the POTS service may not be available or
needed.
[0066] FIG. 6 is a block diagram showing the ADSL modem 550 of FIG.
5 in greater detail. While FIG. 6 shows only one ADSL modem 550, it
should be appreciated that each of the ADSL modems 550 of FIG. 5
may have similar components. As shown in FIG. 6, the ADSL modem 550
at the central office 510 comprises an ADSL transceiver unit
(ATU-C) 605 configured to assemble data for transmission on the
communication line 155. In this regard, the ATU-C 605 comprises
both a fast path and an interleaved path between a multiplexer
(MUX) and synchronization (sync) control block 610 and a tone
ordering circuit 650. The fast path, which provides low latency,
comprises a fast cyclic redundancy checking (CRC) block 615 and a
scrambling and forward error correcting (FEC) block 625. The
interleaved path, which provides a lower error rate at a greater
latency, comprises an interleaved CRC block 620, a scrambling and
FEC block 630, and an interleaver 640. Since MUX/sync control
blocks 610, CRC blocks 615, 620, scrambling and FEC blocks 625,
630, interleavers 640, and tone ordering circuits 650 are known in
the art, further discussion of these components is omitted here.
However, it should be appreciated that the signal, upon traversing
either the fast path or the interleaved path, enters an encoding
and gain scaling block 655, which encodes the data into a
constellation and also scales the data for transmission. The
encoding and gain scaling block 655 is discussed in greater detail
with reference to FIG. 7.
[0067] Once the data has been encoded and gain-scaled, the data is
relayed in parallel blocks to an inverse Fourier transform (IFT)
block 660, which performs a IFT on the parallel data blocks. The
IFT data is conveyed to a parallel-to-serial (P/S) converter 665,
which converts the data into a serial data stream. The serial data
stream is conveyed to a digital-to-analog (D/A) converter and
analog processor 670, which produces an analog signal for data
transmission. Since IFT blocks 660, P/S converters 665, D/A
converters and analog processors 670 are known in the art, further
discussion of these components is omitted here. The analog signal
is transmitted through the communication line 555 by a transmitter
675 in the ATU-C 605.
[0068] FIG. 7 is a block diagram showing logic components in the
encoding and gain scaling block 655 of FIG. 6, which is configured
to encode and gain scale data according to adaptively-filtered PSD
masks. As shown in FIG. 7, the encoder and gain scaler 655
comprises a receiver 710 and a processor 720. The receiver 710 is
configured to receive data from the tone-ordering circuit 650 as
well as signals from the communication line 555. The signals
contain information related to line conditions, which, in turn, are
indicative of services deployed on the communication line 555. The
signals from the communication line 555 comprise signal-to-noise
ratio (SNR) information of the communication line 555, line
attenuation information of the communication line 555, and
information related to usable sub-carriers in the DMT modulated
system. The signals from the communication line 555 are updated for
each data frame being encoded and gain scaled. Thus, the encoder
and gain scaler 655 is continuously updated with information on
concurrently deployed services on the communication line 555.
[0069] The processor 720 is configured to adaptively calculate a
power level of the DMT sub-carriers in response to the signals
received from the communication line 555. In this regard, the
processor 720 comprises service determination logic 730, which
adaptively determines services concurrently deployed on the
communication line 555. In, other words, if the received signal
characteristics change and indicate that line conditions have
changed, then the service determination logic 730 adaptively
determines which services are deployed on the communication line
555 from the changes in line condition.
[0070] Additionally, the processor 720 comprises power
determination logic 740, which adaptively calculates an appropriate
power level for each sub-carrier (or bin) once the services have
been adaptively determined. In this regard, the power determination
logic calculates sub-carrier power levels for each sub-carrier of
each frame, which permits an optimization of power levels as a
function of the determined services deployed on the communication
line 555.
[0071] The processor 720 further comprises power allocation logic
750, which allocates the power to each sub-carrier as determined by
the power determination logic 740. The power allocation logic 750
comprises a power spectral density (PSD) mask 752 and an adaptive
filter 754. Since the sub-carrier power levels may change from
frame to frame due to potential changes in line conditions, a
static PSD mask may not provide optimum sub-carrier power levels.
The adaptive filter 754 adaptively alters the PSD mask 752 as a
function of changing line conditions, thereby generating an
adaptively-filtered PSD mask, which permits optimization of
sub-carrier power levels as a function of changing line
conditions.
[0072] In one embodiment, the adaptive filter 754 is configured to
selectively provide a fixed attenuation over a fixed frequency
range. Thus, if all possible services concurrently deployed on the
communication line 555 are known, then the adaptive filter 754 may
selectively filter or not filter the PSD mask 752 as a function of
the line conditions.
[0073] In another embodiment, the adaptive filter 754 is configured
to provide a variable attenuation over a fixed frequency range of
between approximately 90 kHz and approximately 200 kHz. Thus, if
the frequency range of concurrently deployed services is known to
be between approximately 90 kHz and approximately 200 kHz, but the
fluctuations in power level are not known, then the adaptive filter
may variably attenuate the PSD mask 752 within the fixed frequency
range as a function of the line conditions. In an example
embodiment, the variable attenuation may range from approximately 0
dB to approximately -12 dB. More specifically, in another
embodiment, the variable attenuation may vary in a smaller range
from approximately 0 dB to approximately -8 dB.
[0074] In yet another embodiments the adaptive filter 754 is
configured to provide a variable attenuation over a different fixed
frequency range. In an example embodiment, the fixed frequency
range is between approximately 4 kHz and approximately 26 kHz.
[0075] The adaptive filter 754, in another embodiment, is
configured to provide a variable attenuation over a variable
frequency range. Thus, if neither the frequency range nor the
fluctuations in pommel level due to other services is known with
particularity, then the adaptive filter may variably attenuate the
PSD mask 752 over a variable frequency range as a function of the
line conditions. In an example embodiment, the variable frequency
range may vary anywhere in the range of between approximately 90
kHz and approximately 200 kHz to accommodate services operating
within that bandwidth. More specifically, in another embodiment,
the variable frequency range may vary in a narrower frequency range
of, for example, between approximately 121 kHz and approximately
164 kHz. The 164 kHz frequency is the location of the peak of the
first lobe of the TCM ISDN bandwidth, and the 121 kHz frequency is
the frequency at which downstream performance is optimized,
upstream and downstream signals are balanced, and spectral
compatibility between ADSL and concurrently-deployed TCM ISDN
services is optimized according to predefined conditions. The
variable frequency range may also be between approximately 4 kHz
and approximately 200 kHz, which is the range immediately above the
POTS bandwidth and the upper operating frequencies of ISDN.
[0076] The processor 720 also comprises data loading logic 760,
which loads each of the sub-carriers. In an example embodiment,
once the line conditions have been determined and the optimum
adaptively-filtered PSD mask has been generated or selected, the
data loading logic 760 loads the sub-carriers with data according
to the adaptively-filtered PSD mask. Thus, the data is loaded to
each sub-carrier using an optimized power level as defined by the
adaptively-filtered PSD mask.
[0077] Having described several embodiments of systems configured
to generate adaptively-filtered PSD masks and load sub-carriers
with data according to the adaptively-filtered PSD masks, attention
is turned to FIGS. 8 through 24, which show several transfer
functions of adaptive filters 754 and several embodiments of
adaptively-filtered PSD masks.
[0078] FIG. 8 is a diagram showing one embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7.
Specifically, FIG. 8 shows a portion of the G.992.1 Annex A PSD
mask having, approximately -12 dB attenuation between approximately
92.5 kHz and approximately 122.5 kHz. Thus, rather than having a
uniform peak power of approximately -36.5 dBm/Hz between
approximately 26 kHz and approximately 1104 kHz like the prior-art
Annex A PSD mask of FIG. 1, the adaptively-filtered PSD mask of
FIG. 8 has an approximately -12 dB attenuation "notch" between
approximately 92.5 kHz and approximately 122.5 kHz. The "notch"
reduces the power allocated to the frequency range defined by the
"notch," thereby concomitantly reducing any cross-talk that the DSL
service may induce into other services deployed on the
communication line 555 within that frequency range.
[0079] FIG. 9A is a diagram showing a transfer function associated
with one embodiment of the adaptive filter 754 of FIG. 7, which has
a variable attenuation over a variable frequency range. In this
retard, FIG. 9A shows a general adaptive filter 754 in which the
attenuation bandwidth may be adaptively changed in response to
detected line conditions. As shown in FIG. 9A, one embodiment of
the adaptive filter 754 is configured as a piece-wise linear
function defined by 0 dBm/Hz attenuation below a frequency of 10 (
- A 1 - A 2 .times. ( f f 1 ) )
[0080] attenuation between f.sub.1 and f.sub.2; -A.sub.5 dBm/Hz
attenuation between f.sub.2 and f.sub.3; and 0 dBm/Hz attenuation
above f.sub.3, where -A.sub.1, -A.sub.2, and -A.sub.5, are
attenuation values that are adaptively set in response to detected
line conditions, and f.sub.1, f.sub.2, and f.sub.3 are frequencies
that are adaptively set in response to detected line
conditions.
[0081] FIG. 9B is a diagram shoving a transfer function associated
with one embodiment of the adaptive filter 754 of FIG. 7, which has
a variable attenuation over a fixed frequency range. As shown in
FIG. 9B, this embodiment of the adaptive filter 754 is configured
as a piece-wise linear function defined by 0 dBm/Hz attenuation
below a frequency of approximately 11 99 kHz ; ( - A 1 - A 2
.times. ( f 99 ) )
[0082] attenuation between approximately 99 kHz and approximately
151 kHz; -A.sub.5 dBm/Hz attenuation between approximately 151 kHz
and approximately 164 kHz; and 0 dBm/Hz attenuation above
approximately 164 kHz, where -A.sub.1, -A.sub.2, and -A.sub.5 are
attenuation values that are adaptively set in response to detected
line conditions.
[0083] FIG. 9C is a diagram showing a transfer function associated
with one embodiment of the adaptive filter 754 of FIG. 7, which has
a specific attenuation over a fixed frequency range. As shown in
FIG. 9B, this embodiment of the adaptive filter 754 is configured
as a piece-wise linear function defined by 0 dBm/Hz attenuation
below a frequency of approximately 99 kHz; approximately 12 ( - 12
- 32.84 .times. ( f 99 ) )
[0084] attenuation between approximately 99 kHz and approximately
151 kHz; approximately -32 dBm/Hz attenuation between(approximately
151 kHz and approximately 164 kHz; and 0 dBm/Hz attenuation above
approximately 164 kHz. For a fixed adaptive filter 754 similar to
that shown in FIG. 9C, the processor 720 may selectively apply or
not apply the notch filter to a PSD mask depending on the presence
or absence of other services on the communication line 555, as
indicated by the detected line conditions.
[0085] FIG. 10 is a diagram showing another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 10, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately 13 ( - 97.5 + 17.8 .times. log 2 ( f 4 ) )
[0086] dBm/Hz between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; approximately 14 ( - 49.5 - 78.24 .times.
log 2 ( f 121 ) )
[0087] between approximately 121 kHz and approximately 151 kHz;
approximately -74.5 dBm/Hz between approximately 151 kHz and
approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 15
( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0088] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 10 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility in Annex A and
Annex C far-end cross-talk (FEXT) bit-mapped (FBM) systems. Since
Annex A and Annex C are well known and, also, are described in the
G.992.1 standard, further discussion of Annex A and Annex C is
omitted here.
[0089] FIG. 11 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 11, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately 16 ( - 97.5 + 17.8 .times. log 2 ( f 4 ) )
[0090] dBm/Hz between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; approximately 17 ( - 49.5 - 115.8 .times.
log 2 ( f 121 ) )
[0091] between approximately 121 kHz and approximately 151 kHz;
approximately -86.5 dBm/Hz between approximately 151 kHz and
approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 18
( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0092] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 11 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility in Annex A FBM
systems.
[0093] FIG. 12 is a diagram showing one embodiment of an
adaptively-filtered PSD mask having a variable attenuation
immediately above the plain old telephone system (POTS) bandwidth.
As shown in FIG. 12, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; a variable attenuation of 19 ( - 97 5 + A 1 .times. ( f 4 )
)
[0094] between approximately 4 kHz and approximately 26 kHz, where
A4 is adaptively set in response to detected line conditions;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; approximately 20 ( - 49.5 - 115.8 .times.
log 2 ( f 121 ) )
[0095] between approximately 121 kHz and approximately 151 kHz;
approximately -86.5 dBm/Hz between approximately 151 kHz and
approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 21
( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0096] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz.
[0097] FIG. 13 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask having a variable attenuation between
approximately 121 kHz and 164 kHz. As shown in FIG. 13, the
adaptively-filtered PSD mask is defined by power levels of
approximately -97.5 dBm/Hz below approximately 4 kHz; approximately
22 ( - 97.5 + 17.8 .times. log 2 ( f 4 ) )
[0098] dBm/Hz between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; a variable attenuation of approximately 23 (
- 49.5 - A 2 .times. log 2 ( f 121 ) )
[0099] between approximately 121 kHz and approximately 151 kHz; a
variable attenuation of -A.sub.6 dBm/Hz between approximately 151
kHz and approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 24
( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0100] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz, where
-A.sub.2 and -A.sub.6 are adaptively set in response to detected
line conditions.
[0101] FIG. 14 is a diagram showing one embodiment of an
adaptively-filtered PSD mask having a variable attenuation over a
plurality of different frequency ranges. As shown in FIG. 14, the
adaptively-filtered PSD mask is defined by power levels of
approximately -97.5 dBm/Hz below approximately 4 kHz; a variable
attenuation of 25 ( - 97.5 + A 4 .times. log 2 ( f 4 ) )
[0102] between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 121 kHz; a variable attenuation of approximately 26 (
- 49.5 - A 2 .times. log 2 ( f 121 ) )
[0103] between approximately 121 kHz and approximately 151 kHz; a
variable attenuation of -A.sub.6 dBm/Hz between approximately 151
kHz and approximately 164 kHz; approximately -36.5 dBm/Hz between
approximately 164 kHz and approximately 1104 kHz; approximately 27
( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0104] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz, where
-A.sub.2, -A.sub.4, and -A.sub.6 are adaptively set in response to
detected line conditions.
[0105] FIG. 15A is a diagram showing a transfer function associated
with another embodiment of the adaptive filter 754 of FIG. 7, which
has a variable attenuation over a variable frequency range. In this
regard, FIG. 15A shows a general adaptive filter 754 in which the
attenuation bandwidth may be adaptively changed in response to
detected line conditions. As shown in FIG. 15A, one embodiment of
the adaptive filter 754 is configured as a piece-wise linear
function defined by 0 dBm/Hz attenuation below a frequency of
f.sub.4; -A.sub.3 dBm/Hz attenuation between f.sub.4 and f.sub.5;
and 0 dBm/Hz attenuation above f.sub.5 where -A.sub.3 is an
attenuation value that is adaptively set in response to detected
line conditions, and f.sub.4 and f.sub.5 are frequencies that are
adaptively set in response to detected line conditions.
[0106] FIG. 15B is a diagram showing a transfer function associated
with another embodiment of the adaptive filter 754 of FIG. 7, which
has a variable attenuation over a fixed frequency range. As shown
in FIG. 15B, this embodiment of the adaptive filter 754 is
configured as a piece-wise linear function defined by 0 dBm/Hz
attenuation below a frequency of approximately 100 kHz; -A.sub.3
dBm/Hz attenuation between approximately 100 kHz and approximately
200 kHz; and 0 dBm/Hz attenuation above approximately 200 kHz,
where -A.sub.3 is an attenuation value that is adaptively set in
response to detected line conditions.
[0107] FIG. 15C is a diagram showing a transfer function associated
with another embodiment of the adaptive filter 754 of FIG. 7, which
has a specific attenuation over a fixed frequency range. As shown
in FIG. 15C, this embodiment of the adaptive filter 754 is
configured as a piece-vise linear function defined by 0 dBm/Hz
attenuation below a frequency of approximately 100 kHz;
approximately -8 dBm/Hz attenuation between approximately 100 kHz
and approximately 200 kHz; and 0 dBm/Hz attenuation above
approximately 200 kHz.
[0108] FIG. 15D is a diagram showing a transfer function associated
with another embodiment of the adaptive filter 754 of FIG. 7, which
has a specific attenuation over a fixed frequency range. As shown
in FIG. 15D, this embodiment of the adaptive filter 754 is
configured as a piece-wise linear function defined by 0 dBm/Hz
attenuation below a frequency of approximately 100 kHz;
approximately -12 dBm/Hz attenuation between approximately 100 kHz
and approximately 200 kHz; and 0 dBm/Hz attenuation above
approximately 200 kHz.
[0109] FIG. 16 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 16, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; a variable attenuation of 28 ( - 97.5 + 17.8 .times. ( f 4 )
)
[0110] between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 147 kHz; approximately -41.5 dBm/Hz between
approximately 147 kHz and approximately 164 kHz; approximately
-36.5 dBm/Hz between approximately 164 kHz and approximately 1104
kHz; approximately 29 ( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0111] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz, where
-A.sub.2, -A.sub.4, and -A.sub.6 are adaptively set in response to
detected line conditions.
[0112] FIG. 17 is a diagram showing another embodiment of an
adaptively-filtered PSD mask having a variable attenuation within a
variable frequency range. As shown in FIG. 17, the
adaptively-filtered PSD mask is defined by power levels of
approximately -97.5 dBm/Hz below approximately 4 kHz; a variable
attenuation of 30 ( - 97.5 + 17.8 .times. ( f 4 ) )
[0113] between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and f.sub.4
kHz; a variable attenuation of approximately (-36.5-A.sub.3) dBm/Hz
between f.sub.4 kHz and f.sub.5 kHz; approximately -36.5 dBm/Hz
between f.sub.5 kHz and approximately 1104 kHz; approximately 31 (
- 36.5 - 36 .times. log 2 ( f 1104 ) )
[0114] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz, where
-A.sub.3, f.sub.4, and f.sub.5 are adaptively set in response to
detected line conditions.
[0115] FIG. 18 is a diagram showing another embodiment of an
adaptively-filtered PSD mask having a variable attenuation
immediately above the POTS bandwidth. As shown in FIG. 17, the
adaptively-filtered PSD mask is defined by power levels of
approximately -97.5 dBm/Hz below approximately 4 kHz; a variable
attenuation of 32 ( - 97.5 + A 4 .times. ( f 4 ) )
[0116] between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and
approximately 147 kHz; approximately -41.5 dBm/Hz between
approximately 147 kHz and approximately 164 kHz; approximately
-36.5 dBm/Hz between approximately 164 kHz and approximately 1104
kHz; approximately 33 ( - 36.5 - 36 .times. log 2 ( f 1104 ) )
[0117] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz, where
-A.sub.4 is adaptively set in response to detected line
conditions.
[0118] FIG. 19 is a diagram showing another embodiment of an
adaptively-filtered PSD mask having a variable attenuation in
several non-adjacent bandwidths. As shown in FIG. 19, the
adaptively-filtered PSD mask is defined by power levels of
approximately -97.5 dBm/Hz below approximately 4 kHz; a variable
attenuation of 34 ( - 97.5 + A 4 .times. ( f 4 ) )
[0119] between approximately 4 kHz and approximately 26 kHz;
approximately -36.5 dBm/Hz between approximately 26 kHz and f.sub.4
kHz; a variable attenuation of approximately (-36 5-A.sub.3) dBm/Hz
between f.sub.4 kHz and f.sub.5 kHz; approximately -36.5 dBm/Hz
between f.sub.5 kHz and approximately 1104 kHz; approximately 35 (
- 36.5 - 36 .times. log 2 ( f 1104 ) )
[0120] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90 dBm/Hz above approximately 3093 kHz, where
-A.sub.3, -A.sub.4, f.sub.4, and f.sub.5 are adaptively set in
response to detected line conditions.
[0121] FIG. 20 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 20, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately -94.5 dBm/Hz between approximately 4 kHz and
approximately 31 kHz; approximately 36 ( - 94 5 + 10.88 .times. log
2 ( f 31 ) )
[0122] dBm/Hz between approximately 31 kHz and approximately 104
kHz; approximately 37 ( - 75.5 + 96.54 .times. log 2 ( f 104 )
)
[0123] dBm/Hz between approximately 104 kHz and approximately 134
kHz; approximately 38 ( - 40.2 + 9.6 .times. log 2 ( f 134 ) )
[0124] dBm/Hz between approximately 134 kHz and approximately 175
kHz; approximately -36.5 dBm/Hz between approximately 175 kHz and
approximately 1104 kHz; approximately 39 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )
[0125] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90.5 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 20 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility during a near-end
cross-talk (NEXT) period in extended reach Annex C systems adapted
for time-frequency division duplexing. Since Annex C systems are
known in the art and, also, are described in G.992.1, further
discussion of Annex C systems and their requirements is omitted
here.
[0126] FIG. 21 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 21, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately -94.5 dBm/Hz between approximately 4 kHz and
approximately 24 kHz; approximately 40 ( - 80 + 18.42 .times. log 2
( f 24 ) )
[0127] dBm/Hz between approximately 24 kHz and approximately 43
kHz; approximately 41 ( - 64.5 + 18 .times. log 2 ( f 43 ) )
[0128] dBm/Hz between approximately 43 kHz and approximately 74
kHz; approximately 42 ( - 50.4 + 14 24 .times. log 2 ( f 74 ) )
[0129] dBm/Hz between approximately 74 kHz and approximately 121
kHz; approximately 43 ( - 40.3 + 7.61 .times. log 2 ( f 121 ) )
[0130] dBm/Hz between approximately 121 kHz and approximately 171
kHz; approximately -36.5 dBm/Hz between approximately 171 kHz and
approximately 1104 kHz; approximately 44 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )
[0131] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90.5 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 21 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility during a flu-end
cross-talk (FEXT) period in extended reach Annex C systems adapted
for time-frequency division duplexing.
[0132] FIG. 22 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 22, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately -86.5 dBm/Hz between approximately 4 kHz and
approximately 10 kHz; approximately 45 ( - 86 5 + 25.8 .times. log
2 ( f 10 ) )
[0133] dBm/Hz between approximately 10 kHz and approximately 27
kHz; approximately 46 ( - 49.5 + 9.46 .times. log 2 ( f 27 ) )
[0134] dBm/Hz between approximately 27 kHz and approximately 70
kHz; approximately -36.5 dBm/Hz between approximately 70 kHz and
approximately 1104 kHz; approximately 47 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )
[0135] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90.5 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 22 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility during a far-end
cross-talk (FEXT) period in FEXT bit-mapped (FBM) Annex C
systems.
[0136] FIG. 23 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown, in FIG. 23, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately 48 ( - 97.5 + 11 .times. log 2 ( f 4 ) )
[0137] dBm/Hz between approximately 4 kHz and approximately 50 kHz;
approximately 49 ( - 57.5 + 15.7 .times. log 2 ( f 50 ) )
[0138] dBm/Hz between approximately 50 kHz and approximately 126
kHz; approximately -36.5 dBm/Hz between approximately 164 kHz and
approximately 1104 kHz; approximately 50 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )
[0139] between approximately 1104 kHz and (approximately 3093 kHz;
and approximately -90.5 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 23 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility during a far-end
cross-talk (FEXT) period in Annex C systems adapted for
time-frequency division duplexing.
[0140] FIG. 24 is a diagram showing yet another embodiment of an
adaptively-filtered PSD mask generated by the system of FIG. 7. As
shown in FIG. 24, the adaptively-filtered PSD mask is defined by
power levels of approximately -97.5 dBm/Hz below approximately 4
kHz; approximately -94.5 dBm/Hz between approximately 4 kHz and
approximately 32 kHz; approximately 51 ( - 94.5 + 20.65 .times. log
2 ( f 32 ) )
[0141] dBm/Hz between approximately 32 kHz and approximately 109
kHz; approximately 52 ( - 58 + 58 .times. log 2 ( f 109 ) )
[0142] dBm/Hz between approximately 109 kHz and approximately 138
kHz; approximately 53 ( - 38.3 + 3.36 .times. log 2 ( f 138 ) )
[0143] dBm/Hz between approximately 138 kHz and approximately 200
kHz; approximately -36.5 dBm/Hz between approximately 200 kHz and
approximately 1104 kHz; approximately 54 ( - 36.5 - 36 .times. log
2 ( f 1104 ) )
[0144] between approximately 1104 kHz and approximately 3093 kHz;
and approximately -90.5 dBm/Hz above approximately 3093 kHz.
Specifically, the PSD mask shown in FIG. 24 is configured to
optimize downstream performance, balance downstream and upstream
signal ratios, and provide spectral compatibility during a near-end
cross-talk (NEXT) period in Annex C systems adapted for
time-frequency division duplexing.
[0145] FIG. 25 is a flowchart showing one embodiment of a method
employing adaptively-filtered PSD masks. As shown in FIG. 25, one
embodiment of the method begins when a DMT-modulated communication
system receives (2520) a signal from a communication line 555. The
received (2520) signal has information indicative of services
deployed on the communication line 555. In this regard, the
received (2520) signal contains information related to line
conditions. Upon receiving (2520) the signal, the DMT-modulated
communications system adaptively determines (2530) a power level of
a DMT sub-carrier. Additionally, the DMT-modulated communication
system adaptively attenuates (2540) power within a portion of a PSD
mask using the adaptively determined (2530) power level of the DMT
sub-carrier. Thereafter, the DMT sub-carrier is loaded (2550) with
data according to the adaptively determined (2530) power level.
[0146] In an example embodiment. the method of FIG. 25 may be
performed by the systems described with reference to FIGS. 5
through 24. However, it should be understood that other
communication systems employing DMT modulation might also perform
the steps described with reference to FIG. 25.
[0147] The service determination logic 730, the power determination
logic 740, the power allocation logic 750, and the data loading
logic 760 of the present invention can be implemented in hardware,
software, firmware, or a combination thereof. In the preferred
embodiment(s), the service determination logic 730, the power
determination logic 740, the power allocation logic 750, and the
data loading logic 760 is implemented in hardware using any or a
combination of the following technologies, which are all well known
in the art: a discrete logic circuit(s) having logic gates for
implementing logic functions upon data signals, an application
specific integrated circuit (ASIC) having appropriate combinational
logic gates, a programmable gate array(s) (PGA), a field
programmable (late array (FPGA), etc. In an alternative embodiment,
the service determination logic 730, the power determination logic
740, the power allocation logic 750, and the data loading logic 760
is implemented in software or firmware that is stored in a memory
and that is executed by a suitable instruction execution
system.
[0148] Any process descriptions or blocks in flow charts should be
understood as representing modules, segments, or portions of code
which include one or more executable instructions for implementing)
specific logical functions or steps in the process, and alternate
implementations are included within the scope of the preferred
embodiment of the present invention in which functions may be
executed out of order from that shown or discussed, including
substantially concurrently or in reverse order, depending on the
functionality involved, as would be understood by those reasonably
skilled in the art of the present invention.
[0149] Although an exemplary embodiment of the present invention
has been shown and described, it will be apparent to those of
ordinary skill in the art that a number of changes, modifications,
or alterations to the invention as described may be made, none of
which depart from the spirit of the present invention. For example,
while the processor and logic configured to adaptively calculate
the DMT sub-carrier power level are shown within the encoding and
gain scaling block, it should be appreciated that the processor and
logic configured to adaptively calculate the DMT sub-carrier power
level may also be located as a separate unit outside of the
encoding and gain scaling block. Also, while exemplary embodiments
of the present invention have been described with reference to a
digital subscriber line (DSL) system, it should be understood that
the systems and methods presented herein may be implemented in
other digital communication systems that employ sub-carriers for
data transmission. Additionally, while specific examples of PSD
masks have been shown with reference to FIGS. 8, 10-14, and 16-24,
it should be appreciated that the various cutoff frequencies and
attenuation values shown as fixed values may be adjusted to
maximize downstream performance, balance upstream and downstream
signals, and provide greater spectral compatibility with
concurrently deployed services, such as ISDN services. All such
changes, modifications, and altercations should therefore be seen
as within the scope of the present invention.
* * * * *