Receiver employing non-pilot reference channels for equalizing a received signal
View Patent ↗In one embodiment, a receiver has a reference generator and a main equalizer. The reference generator equalizes a received signal using one or more pilot reference signals. Then, the reference generator decodes one or more predetermined data channels of the equalized signal, makes hard decisions on the data of each decoded channel, and regenerates the original coding sequence of each decoded channel. The main equalizer uses each re-encoded channel as an additional reference signal along with one or more pilot signals to equalize a time-delayed version of the received signal. In alternative embodiments, the receiver might also have a step-size generator which selects optimum step sizes from a look-up table based on the number of re-encoded channels and the power of those channels. The step size is then used by the main equalizer along with the re-encoded channels to equalize the time-delayed received signal.
1. A method for equalizing received signals, the method comprising:
(a) equalizing a first set of one or more received signals based on at least one pilot channel in the received signals to generate a first set of one or more equalized signals;
(b) processing the first set of one or more equalized signals to generate a first set of one or more decoded data streams corresponding to a first set of one or more non-pilot channels in the received signals;
(c) generating one or more reference signals from the first set of one or more decoded data streams; and
(d) equalizing a second set of one or more received signals based on a combination of (1) the at least one pilot channel and (2) the one or more reference signals to generate a second set of one or more equalized signals, wherein:
at least one of steps (a)-(d) is implemented in a receiver and
step (d) comprises filtering the second set of one or more received signals based on a second set of filter coefficients, wherein the second set of filter coefficients is adaptively generated by:
(1) calculating an error signal by comparing the second set of one or more equalized signals to both (i) the at least one pilot channel and (ii) the one or more reference signals; and
(2) updating the second set of filter coefficients based on the error signal.
2. The invention of claim 1 , further comprising the step of processing the second set of one or more equalized signals to generate a second set of one or more decoded data streams corresponding to a second set of one or more non-pilot channels in the received signals.
3. The invention of claim 1 , wherein the second set of one or more received signals is a time-delayed version of the first set of one or more received signals.
4. The invention of claim 1 , wherein updating the second set of filter coefficients is further based on a step-size value generated as a function of the number and power of the one or more non-pilot channels used to generate the one or more reference signals.
5. The invention of claim 1 , wherein step (a) comprises filtering the first set of one or more received signals using the second set of filter coefficients.
6. The invention of claim 1 , wherein step (c) comprises:
(1) generating a first set of hard decisions for the first set of one or more decoded data streams; and
(2) recoding the first set of hard decisions for use as the one or more reference signals.
7. The invention of claim 1 , wherein:
steps (a)-(c) are implemented by a reference generator; and
step (d) is implemented by an equalizer.
8. A method for equalizing received signals, the method comprising:
(a) equalizing a first set of one or more received signals based on at least one pilot channel in the received signals to generate a first set of one or more equalized signals;
(b) processing the first set of one or more equalized signals to generate a first set of one or more decoded data streams corresponding to a first set of one or more non-pilot channels in the received signals;
(c) generating one or more reference signals from the first set of one or more decoded data streams; and
(d) equalizing a second set of one or more received signals based on a combination of (1) the at least one pilot channel and (2) the one or more reference signals to generate a second set of one or more equalized signals, wherein:
at least one of steps (a)-(d) is implemented in a receiver; and
steps (b), (c), and (d) are repeated one or more times for the first set of one or more received signals, wherein, for each repetition, the equalized signals processed in step (b) are the equalized signals generated in the previous implementation of step (d).
9. The invention of claim 8 , wherein, for the first set of one or more received signals, two or more sets of one or more reference signals are iteratively generated using a single reference generator.
10. The invention of claim 8 , wherein, for the first set of one or more received signals, two or more sets of one or more reference signals are generated using two or more reference generators in a pipelined manner.
11. A method for equalizing received signals, the method comprising:
(a) equalizing a first set of one or more received signals based on at least one pilot channel in the received signals to generate a first set of one or more equalized signals;
(b) processing the first set of one or more equalized signals to generate a first set of one or more decoded data streams corresponding to a first set of one or more non-pilot channels in the received signals;
(c) generating one or more reference signals from the first set of one or more decoded data streams; and
(d) equalizing a second set of one or more received signals based on a combination of (1) the at least one pilot channel and (2) the one or more reference signals to generate a second set of one or more equalized signals, wherein:
at least one of steps (a)-(d) is implemented in a receiver; and
step (c) comprises:
(1) determining whether a power value associated with each of the one or more non pilot channels satisfies a power-threshold condition; and
(2) enabling, for use in generating a reference signal, each decoded data stream corresponding to a non-pilot channel whose associated power value satisfies the power-threshold condition.
12. The invention of claim 11 , wherein each power value is a power ratio based on the power of the associated non-pilot channel and the power of the at least one pilot channel.
13. A method for equalizing a received signal in a receiver by filtering the received signal based on a set of filter coefficients to generate an equalized signal, wherein the set of filter coefficients is adaptively generated by:
(1) calculating an error signal by comparing the equalized signal to one or more reference channels comprising at least a first channel having a bit pattern known a priori by the receiver wherein the first channel is used by the receiver for a purpose other than as a pilot channel; and
(2) updating the set of filter coefficients based on the error signal.
14. The invention of claim 13 , wherein the first channel is a synchronization channel.