Noise measurement method and a related receiving digital subscriber line modem
View Patent ↗A transmitting Digital Subscriber Line (DSL) modem is coupled over a communication line to the receiving DSL modem. A receiving DSL modem receives a symbol transmitted by the transmitting DSL modem. Subsequently the receiving DSL modem demaps the symbol received onto a constellation point. The receiving DSL modem then performs a noise measurement based on the difference between the received symbol and the determined constellation point. Further, the receiving DSL modem determines a frequency of the symbols incorrectly demapped and subsequently the receiving DSL modem corrects the noise measurement using the frequency of the symbols incorrectly demapped.
1. A noise measurement method for noise measurement in a
transmission Digital Subscriber Line system, said system comprising a transmitting Digital Subscriber Line modem and a receiving Digital Subscriber Line modem, said transmitting Digital Subscriber Line modem being coupled over a communication line to said receiving Digital Subscriber Line modem, the method comprising:
receiving a symbol, at said receiving Digital Subscriber Line modem, transmitted by said transmitting Digital Subscriber Line modem;
demapping, at said receiving Digital Subscriber Line modem, said symbol received on a constellation point;
performing, at said receiving Digital Subscriber Line modem, the noise measurement based on the difference between the received symbol and the constellation point;
determining, at said receiving Digital Subscriber Line modem, a frequency of symbols incorrectly demapped; and
correcting, at said receiving Digital Subscriber Line modem, said noise measurement using said frequency of said symbols incorrectly demapped.
2. The noise measurement method according to claim 1 , wherein said frequency determining step determines said frequency based on determining a number of symbols received in an erasure zone.
3. The noise measurement method according to claim 1 , wherein said frequency determining step determines said frequency based on said receiving Digital Subscriber Line modem determining a deviation from a normal distribution of the measured noise on symbols received.
4. The noise measurement method according to claim 3 , wherein said frequency determining step determines said deviation from a normal distribution of the measured noise on received symbols by determining the ratio of
(
E
{
x
n
}
)
(
n
-
m
)
E
{
x
m
}
where
x=the measured noise, and n and m define a higher order moment.
5. The noise measurement method according to claim 3 , wherein said frequency determining step determines said deviation from a normal distribution of the measured noise on received symbols by determining the ratio
alpha
=
(
E
{
x
2
}
)
2
E
{
x
4
}
where
x=the measured noise.
6. A receiving Digital Subscriber Line modem for use in a
noise measurement in a transmission Digital Subscriber Line system, said system comprising a transmitting Digital Subscriber Line modem and said receiving Digital Subscriber Line modem, said transmitting Digital Subscriber Line modem being coupled over a communication line to said receiving Digital Subscriber Line modem, said receiving Digital Subscriber Line modem comprising:
a signal reception part configured to receive a symbol transmitted by said transmitting Digital Subscriber Line modem;
a symbol demapping part, coupled to an output of said signal reception part and configured to perform the demapping of said symbol received on a constellation point;
a noise measuring part, coupled to the output of said signal reception part, coupled to an output of said symbol demapping part, and configured to measure said noise measurement based on the difference between said received symbol and said constellation point;
a deviation frequency determination part, coupled to the output of said signal reception part, coupled to the output of said symbol demapping part, coupled to an output of said noise measuring part, and configured to determine a frequency of symbols incorrectly demapped; and
a noise measurement correction part, coupled to an output of said deviation frequency determination part and configured to correct said noise measurement, using said frequency of said symbols incorrectly demapped.
7. The receiving Digital Subscriber Line modem according to claim 6 , wherein said deviation frequency determination part is further configured to determine said frequency using a number of symbols received in an erasure zone.
8. The receiving Digital Subscriber Line modem according to claim 6 , wherein said deviation frequency determination part is further configured to determine said frequency using a deviation from a normal distribution of the measured noise on symbols received.
9. The receiving Digital Subscriber Line modem according to claim 6 , wherein said deviation frequency determination part is further configured to determine said frequency using a deviation from a normal distribution of the measured noise on symbols received by determining the ratio of
(
E
{
x
n
}
)
(
n
-
m
)
E
{
x
m
}
where
x=the measured noise, and n and m define a higher order moment.
10. The receiving Digital Subscriber Line modem according to claim 6 , wherein said deviation frequency determination part is further configured to determine said frequency using a deviation from a normal distribution of the measured noise on symbols received by determining the ratio
alpha
=
(
E
{
x
2
}
)
2
E
{
x
4
}
.
wherein
x=the measured noise.