Method and apparatus for adjusting a symbol decision threshold at a receiver in a communication network
View Patent ↗A method and apparatus for adjusting a symbol decision threshold at a receiver in a communication network enables the receiver to be adapted to more correctly receive symbols as transmitted by a transmitter. In one embodiment, a received bit imbalance is detected by a receiver prior to error correction and after error correction to determine whether an error component of the received signal contains larger numbers of ones or larger numbers of zeros. Where the transmitter scrambles the signal prior to transmission, the receiver will also scramble the signal after error correction and prior to counting the number of zeros or ones. Any imbalance between the number of transmitted and received ones or zeros is used as feedback to adjust threshold values used by detectors to fine tune the manner in which the receiver interprets incoming signals.
1. A method of adjusting a symbol decision threshold at a receiver in a communication network, the method comprising the steps of:
receiving a signal by the receiver, the signal containing a data component and an error component;
counting a number of ones or zeros of the received signal containing the data component and the error component;
error correcting the received signal to remove the error component from the signal to isolate the data component;
counting a number of ones or zeros in the data component;
comparing the number of ones or zeros in the data component with the number of ones or zeros of the received signal to determine the number of ones or zeros in the error component; and
utilizing the determined number of ones or zeros of the error component to adjust a symbol decision threshold at the receiver.
2. The method of claim 1 , wherein the received signal is scrambled.
3. A method of adjusting a symbol decision threshold at a receiver in a communication network, the method comprising the steps of:
receiving a signal by the receiver, the signal containing a data component and an error component;
counting a number of ones or zeros of the error component to isolate the number of ones or zeros of the error component; and
utilizing the counted number of ones or zeros of the error component to adjust a symbol decision threshold at the receiver;
wherein the step of counting a number of ones or zeros of the error component comprises the steps of:
counting a number of ones or zeros of the received signal;
correcting the received signal to remove the error component from the signal to isolate the data component;
counting a number of ones or zeros in the data component; and
comparing the number of ones or zeros in the data component with the number of ones or zeros of the received signal to isolate the number of ones or zeros in the error component;
wherein the received signal is scrambled;
the method further comprising the step of unscrambling the signal before performing the step of correcting the received signal to remove the error component.
4. The method of claim 3 , further comprising the step of scrambling the data component before performing the step of counting a number of ones or zeros in the data component.
5. A method of adjusting a symbol decision threshold at a receiver in a communication network, the method comprising the steps of:
receiving a signal by the receiver, the signal containing a data component and an error component;
isolating a number of ones or zeros of the error component; and
utilizing the isolated number of ones or zeros of the error component to adjust a symbol decision threshold at the receiver;
wherein the step of isolating a number of ones or zeros of the error component comprises the steps of:
counting a number of ones or zeros of the received signal;
correcting the received signal to remove the error component from the signal to isolate the data component;
counting a number of ones or zeros in the data component; and
comparing the number of ones or zeros in the data component with the number of ones or zeros of the received signal to isolate the number of ones or zeros in the error component; and
wherein the step of comparing the number of ones or zeros in the data component with the number of ones or zeros of the received signal comprises subtracting the number of ones or zeros in the data component from the number of ones or zeros of the received signal.
6. A method of adjusting a symbol decision threshold at a receiver in a communication network, the method comprising the steps of:
receiving a signal by the receiver, the signal containing a data component and an error component;
isolating a number of ones or zeros of the error component; and
utilizing the isolated number of ones or zeros of the error component to adjust a symbol decision threshold at the receiver;
wherein the step of isolating a number of ones or zeros of the error component comprises the steps of:
counting a number of ones or zeros of the received signal;
correcting the received signal to remove the error component from the signal to isolate the data component;
counting a number of ones or zeros in the data component; and
comparing the number of ones or zeros in the data component with the number of ones or zeros of the received signal to isolate the number of ones or zeros in the error component; and
wherein the step of comparing the number of ones or zeros in the data component with the number of ones or zeros of the received signal comprises subtracting the number of ones or zeros of the received signal from the number of ones or zeros in the data component.
7. The method of claim 1 , wherein the step of comparing comprises determining the number of ones of the error component and, if the determined number of ones in the error component is positive, the step of utilizing the determined number of ones or zeros of the error component comprises the step of increasing a symbol decision threshold at the receiver.
8. The method of claim 1 , wherein the step of comparing comprises determining the number of ones of the error component and, if the determined number of ones in the error component is negative, the step of utilizing the determined number of ones or zeros of the error component comprises the step of decreasing a symbol decision threshold at the receiver.
9. The method of claim 1 , wherein the step of comparing comprises determining the number of zeros of the error component and, if the determined number of zeros in the error component is positive, the step of utilizing the determined number of ones or zeros of the error component comprises the step of decreasing a symbol decision threshold at the receiver.
10. The method of claim 1 , wherein the step of comparing comprises determining the number of zeros of the error component and, if the determined number of zeros in the error component is negative, the step of utilizing the determined number of ones or zeros of the error component comprises the step of increasing a symbol decision threshold at the receiver.
11. A method of adjusting a symbol decision threshold at a receiver in a communication network, the method comprising the steps of:
receiving a scrambled signal by the receiver, the signal containing a data component and an error component;
counting a number of zeros or ones of the received signal;
unscrambling the signal;
performing error correction on the signal to remove the error component to isolate the data component;
scrambling the data component;
counting a number of zeros or ones of the scrambled data component;
comparing the counted number of zeros or ones of the received signal and the counted number of zeros or ones of the scrambled data component; and
using a result of the step of comparing the counted number of zeros or ones of the received signal and the counted number of zeros or ones of the scrambled data component to adjust a symbol decision threshold at the receiver.
12. The method of claim 11 , wherein the step of scrambling the data component uses a scrambler that is the same as a scrambler used to create the scrambled signal by a transmitter prior to transmission to the receiver.
13. The method of claim 11 , wherein if the step of counting a number of zeros or ones of the received signal is performed by counting a number of zeros of the received signal, then the step of counting a number of zeros or ones of the scrambled data component is performed by counting a number of zeros of the scrambled data component.
14. The method of claim 11 , wherein if the step of counting a number of zeros or ones of the received signal is performed by counting a number of ones of the received signal, then the step of counting a number of zeros or ones of the scrambled data component is performed by counting a number of ones of the scrambled data component.
15. A receiver, comprising:
a physical interface using at least one threshold to make symbol decisions on a received signal;
a descrambler to descramble the received signal;
an error corrector to remove an error component from the received signal to extract a data component;
a scrambler to scramble a data component; and
a comparator to compare a number of ones or zeros in the received signal with a number of ones or zeros in the scrambled data component.
16. The receiver or claim 15 , wherein the at least one threshold is adjustable and wherein the physical interface uses a result of the comparator to adjust the at least one threshold.