Cooperative MIMO for alien noise cancellation (COMAC) for upstream VDSL systems
View Patent ↗Included are embodiments for reducing alien crosstalk. At least one embodiment of a method includes receiving noise data associated with a first user signal on a first tone, receiving noise data associated with a second user signal on the first tone, and receiving at least one alien crosstalk canceller coefficient for the first user on the first tone. Some embodiments include applying the at least one alien crosstalk canceller coefficient to the second user signal to reduce alien crosstalk for the first user signal.
1. A method in a digital subscriber line (DSL) system, the method comprising:
receiving alien noise data associated with a first user signal on a first tone;
receiving alien noise data associated with a second user signal on the first tone;
receiving at least one alien crosstalk canceller coefficient for the first user signal on the first tone, wherein the at least one alien crosstalk canceller coefficient is associated with alien noise originated from a service different from the DSL system; and
applying the at least one alien crosstalk canceller coefficient to the second user signal to reduce alien crosstalk for the first user signal based on the existing correlation between the first user signal on the first tone and the second user signal on the first tone.
2. The method of claim 1 , wherein the method is performed in a vectored digital subscriber line (DSL) environment.
3. The method of claim 1 , wherein the first user signal and second user signal on the first tone are derived at the output of a frequency-domain equalizer followed by a self-far end crosstalk (self-FEXT) canceller.
4. The method of claim 1 , wherein the at least one crosstalk canceller coefficient for the first user is determined using an initialization computation.
5. The method of claim 4 , wherein the initialization computation includes implementing at least one of the following functions:
α m opt =Γ −m −1 p m and
α m [t n ]=α m [t n−1 ]+μw −m [t n ]−α m T [t n−1 ]w −m [t n ])*
wherein w m denotes the noise associated with the first user signal on the first tone and w −m denotes the noise associated with the second user signal on the first tone.
6. The method of claim 1 , wherein the at least one crosstalk canceller coefficient for the first user is updated using an adaptation computation.
7. The method of claim 6 , wherein the adaptation computation includes implementing at least one of the following functions:
e m [t n ]=z′ m [t n ]−demapped( z′ m [t n ]) and
α m [t n ]=α m [t n−1 ]+μw −m [t n ]e m *[t n ])
wherein z m ′ denotes the first user signal with reduced alien crosstalk.
8. The method of claim 1 , where the noise data associated with the first user signal and the noise data associated with the second user signal comprise the respective slicer errors.
9. The method of claim 1 , further comprising reducing the alien crosstalk for at least one of the following: the first user signal and the second user signal.
10. A digital subscriber line (DSL) system, comprising:
a first receiving component configured to receive alien noise data associated with a first user signal on a first tone;
a second receiving component configured to receive alien noise data associated with a second user signal on the first tone;
a third receiving component configured to receive at least one alien crosstalk canceller coefficient for the first user signal on the first tone, wherein the at least one alien crosstalk canceller coefficient is associated with alien noise originated from a service different from the DSL system;
an applying component configured to apply the at least one alien crosstalk canceller coefficient to the second user signal to compute a correction signal for the first user; and
a reducing component configured to combine the correction signal for the first user and the first user signal to reduce alien crosstalk into the first user signal based on the existing correlation between the first user signal on the first tone and the second user signal on the first tone.
11. The system of claim 10 , wherein the system is configured to operate in a vectored digital subscriber line (DSL) environment.
12. The system of claim 10 , wherein the first user signal and second user signal on the first tone are derived at the output of a frequency-domain equalizer followed by a self-far end crosstalk (self-FEXT) canceller.
13. The system of claim 10 , wherein the at least one crosstalk canceller coefficient for the first user is determined using an initialization computation.
14. The system of claim 10 , wherein the at least one crosstalk canceller coefficient for the first user is updated using an adaptation computation.
15. The system of claim 10 , further comprising:
a first determining component configured to determine a slicer error for the first user signal; and
a second determining component configured to determine a slicer error for the second user signal.
16. The system of claim 10 , wherein the system is implemented as a computer readable medium.
17. A digital subscriber line (DSL) system, comprising:
means for receiving alien noise data associated with a first user signal on a first tone;
means for receiving alien noise data associated with a second user signal on the first tone;
means for receiving at least one alien crosstalk canceller coefficient for the first user signal on the first tone, wherein the at least one alien crosstalk canceller coefficient is associated with alien noise originated from a service different from the DSL system; and
means for applying the at least one alien crosstalk canceller coefficient to the second user signal to reduce alien crosstalk into the first user signal based on the existing correlation between the first user signal on the first tone and the second user signal on the first tone.
18. The system of claim 17 , wherein the system is implemented in a vectored digital subscriber line (DSL) environment.
19. The system of claim 17 , wherein the first user signal and second user signal on the first tone are derived at the output of a frequency-domain equalizer followed by a self-far end crosstalk (self-FEXT) canceller.
20. The system of claim 17 , wherein the at least one crosstalk canceller coefficient for the first user is determined using an initialization computation.
21. The system of claim 17 , wherein the at least one crosstalk canceller coefficient for the first user is updated using an adaptation computation.
22. The system of claim 17 , further comprising:
means for determining a slicer error for the first user signal; and
means for determining a slicer error for the second user signal.
23. The method of claim 1 , wherein the service different from the DSL system shares a same cable as the DSL system.
24. The system of claim 10 , wherein the service different from the DSL system shares a same cable as the DSL system.
25. The system of claim 17 , wherein the service different from the DSL system shares a same cable as the DSL system.