Method and apparatus for generating a channel estimate using a non-pilot portion of a signal
View Patent ↗An apparatus and a method for generating a channel estimate using a non-pilot signal. More specifically, there is provided a receiver comprising a device configured to receive a transmitted signal having a pilot portion and non-pilot portion and a channel estimator configured to calculate a channel estimate based on the non-pilot portion of the transmitted signal and to send the channel estimate to the device. A method for implementing the improvement is also provided.
1. A receiver comprising:
a device, having a RAKE combiner, configured to receive a transmitted signal having a pilot portion and non-pilot portion;
a soft turbo encoder configured to calculate a reliability value for at least a portion of the transmitted signal, wherein the calculated reliability value is for a parity bit of the transmitted signal and is calculated based on a reliability value for a plurality of systematic bits of the transmitted signal; and
a channel estimator configured to:
calculate a channel estimate based on the non-pilot portion; and
send the channel estimate to the device.
2. The receiver, as set forth in claim 1 , wherein the device comprises:
a soft modulator configured to:
receive the reliability value from the soft turbo encoder;
determine if a portion of the transmitted signal is reliable based on the reliability value; and
send the reliable portion of the transmitted signal to the channel estimator.
3. The receiver, as set forth in claim 2 , wherein the soft modulator is configured to determine a probability for a particular symbol based on whether LLRs for the systematic and parity bits exceed a threshold.
4. The receiver, as set forth in claim 2 , wherein the soft modulator is configured to calculate the reliability of a symbol of the transmitted signal.
5. The receiver, as set forth in claim 4 , wherein the soft modulator is configured to determine if the symbol is reliable by determining if a logarithm likelihood ratio for each bit within the symbol exceeds a predetermined threshold.
6. The receiver, as set forth in claim 1 , wherein the device comprises:
a turbo decoder configured to calculate a reliability value for a plurality of systematic and parity bits of the transmitted signal; and
a soft modulator configured to:
receive the reliability value from the turbo decoder;
determine if a portion of the transmitted signal is reliable based on the reliability value; and
send the reliable portion of the transmitted signal to the channel estimator.
7. The receiver, as set forth in claim 6 , wherein the turbo decoder is configured to calculate a logarithm likelihood ratio for the plurality of systematic and parity bits of the transmitted signal.
8. The receiver, as set forth in claim 7 , wherein the soft modulator is configured to determine if a symbol of the transmitted signal is reliable by determining if the logarithm likelihood ratios for the systematic and parity bits that comprise the symbol exceed a predetermined threshold.
9. The receiver, as set forth in claim 1 , wherein the channel estimator is configured to transmit the channel estimate to a RAKE finger in the RAKE combiner.
10. The receiver, as set forth in claim 1 , wherein the device comprises a demodulator configured to receive a RAKE-combined signal, and wherein the channel estimator is configured to calculate the channel estimate based on the non-pilot portion of the RAKE-combined signal and to send the channel estimate to the demodulator.
11. The receiver, as set forth in claim 10 , wherein the demodulator is configured to demodulate the RAKE-combined signal based on the channel estimate received from the channel estimator.
12. The receiver, as set forth in claim 10 , wherein a soft modulator is configured to calculate a reliability value for a parity bit of the transmitted signal based on a reliability value for a systematic bit of the transmitted signal.
13. A method of signal reception comprising:
receiving a transmitted signal having a pilot portion and a non-pilot portion;
calculating a reliability value for the non-pilot portion by calculating a logarithm likelihood ratio for a systematic bit in the non-pilot portion with a turbo decoder, and calculating a logarithm likelihood ratio for a parity bit in the non-pilot portion with a soft turbo encoder;
generating a channel estimate based at least partially on the reliability value; and
sending the channel estimate to a device having a RAKE combiner.
14. The method, as set forth in claim 13 , wherein calculating the reliability value comprises calculating a logarithm likelihood ratio for both systematic and parity bits in the non-pilot portion with a turbo decoder.
15. The method, as set forth in claim 13 , wherein generating the channel estimate comprises generating the channel estimate based exclusively on the reliability value, wherein the reliability value is calculated based exclusively on the non-pilot portion.
16. The method, as set forth in claim 13 , wherein sending the channel estimate to a device comprises sending the channel estimate to one of a plurality of RAKE fingers in the RAKE combiner.
17. The method, as set forth in claim 13 , wherein sending the channel estimate to a device comprises sending the channel estimate to a demodulator.
18. The method, as set forth in claim 13 , comprising processing the non-pilot portion according to the following equation:
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