Method and apparatus for removing crosstalk and other interference in communications systems
View Patent ↗An approach for estimating and removing crosstalk and other interference in a communications receiver is disclosed. The approach enables crosstalk and interference of arbitrary origin and power spectral density to be removed from a received signal, thereby improving the signal to noise ratio (SNR). A receiver samples the received signal at a rate N times the required sampling rate, and splits the signal into N separate observation sequences, all at the required sampling rate. The N observation sequences are separated into a data signal and a crosstalk signal. The crosstalk signal is discarded, while the data signal is passed to equalization and demodulation circuits of the receiver.
1. A computer-readable medium carrying one or more sequences of one or more instructions for processing data received from a communications channel, the one or more sequences of one or more instructions including instructions which, when executed by one or more processors, cause the one or more processors to perform the steps of:
sampling the received data at a specified sampling rate to generate sampled data;
separating the sampled data into two or more subchannels of information;
filtering the two or more subchannels of information to shorten the impulse response length of the two or more subchannels of information;
after filtering the two or more subchannels of information to shorten the impulse response length of the two or more subchannels of information, filtering the two or more subchannels of information using one or more finite impulse response filters to remove crosstalk and other interference; and
after filtering the two or more subchannels of information using one or more finite impulse response filters to remove crosstalk and other interference, combining the two or more subchannels of information to generate combined data.
2. The computer-readable medium as recited in claim 1 , wherein the specified sampling rate varies over time.
3. The computer-readable medium as recited in claim 1 , wherein the specified sampling rate is N times a minimum sampling rate.
4. The computer-readable medium as recited in claim 3 , wherein the step of separating the sampled data into two or more subchannels of information includes separating the sampled data into N subchannels of information.
5. The computer-readable medium as recited in claim 1 , wherein the one or more finite impulse response filters are determined by determining an impulse response of each of the two or more subchannels of information.
6. The computer-readable medium as recited in claim 5 , further comprising determining a noise covariance matrix and a signal covariance matrix for the two or more subchannels of information.
7. The computer-readable medium as recited in claim 1 , wherein the one or more finite impulse response filters are determined by solving a generalized Eigen value problem.
8. The computer-readable medium as recited in claim 7 , wherein the one or more finite impulse response filters are determined by converting the generalized Eigen value problem to a computationally stable symmetric Eigen value problem.
9. The computer-readable medium as recited in claim 1 , further comprising equalizing the combined data to shorten the impulse response of the communications channel.
10. The computer-readable medium as recited in claim 1 , further comprising equalizing the combined data to equalize the communications channel.
11. The computer-readable medium as recited in claim 1 , wherein the communications channel includes one or more twisted pair telephone lines.
12. The computer-readable medium as recited in claim 1 , wherein the communications channel is a wireless communications channel.
13. The computer-readable medium as recited in claim 1 , wherein the communications channel is part of a single carrier system.
14. An apparatus for processing data received from a communications channel, the apparatus comprising:
a sampling mechanism configured to sample the received data at a specified sampling rate to generate sampled data;
a separator configured to separate the sampled data into two or more subchannels of information;
one or more shortening filters configured to filter the two or more subchannels of information to shorten the impulse response length of the two or more subchannels of information;
one or more finite impulse response filters configured to after the filtering of the two or more subchannels of information by the one or more shortening filters to shorten the impulse response length of the two or more subchannels of information, filter the two or more subchannels of information to remove crosstalk and other interference; and
a combiner configured to after the filtering of the two or more subchannels of information by the one or more finite impulse response filters to remove crosstalk and other interference, combine the two or more subchannels of information to generate combined data.
15. The apparatus as recited in claim 14 , wherein the specified sampling rate varies over time.
16. The apparatus as recited in claim 14 , wherein the specified sampling rate is N times a minimum sampling rate, wherein N is an integer.
17. The apparatus as recited in claim 16 , wherein the separator is further configured to separate the sampled data into N subchannels of information, wherein N is an integer.
18. The apparatus as recited in claim 14 , wherein the one or more finite impulse response filters are determined by determining an impulse response of each of the two or more subchannels of information.
19. The apparatus as recited in claim 18 , wherein the one or more finite impulse response filters are determined by determining a noise covariance matrix and a signal covariance matrix for the two or more subchannels of information.
20. The apparatus as recited in claim 14 , wherein the one or more finite impulse response filters are determined by solving a generalized Eigen value problem.
21. The apparatus as recited in claim 20 , wherein the one or more finite impulse response filters are determined by converting the generalized Eigen value problem to a computationally stable symmetric Eigen value problem.
22. The apparatus as recited in claim 14 , further comprising an equalizer configured to equalize the combined data to shorten the impulse response of the communications channel.
23. The apparatus as recited in claim 14 , further comprising an equalizer configured to equalize the combined data to equalize the communications channel.
24. The apparatus as recited in claim 14 , wherein the communications channel includes one or more twisted pair telephone lines.
25. The apparatus as recited in claim 14 , wherein the communications channel is a wireless communications channel.
26. The apparatus as recited in claim 14 , wherein the communications channel is part of a single carrier system.