Method and apparatus for demodulating a received signal within a coded system
View Patent ↗A receiver includes an input, a correlator, a phase-assisted demodulator, and an output. The input receives a modulated signal and the correlator generates a plurality of correlation values from the received modulated signal The phase-assisted demodulator, coupled to the correlator, selects one of the plurality of correlation values based on relative magnitude and relative phase information of at least a two of the plurality of correlation values. The output provides a demodulated signal, corresponding to the modulated signal, based on the selected one of the plurality of correlation values. The correlation value having the largest magnitude and the correlation value having the second largest magnitude is used in combination with the relative phase information of both correlation values in determining which correlation value corresponds to the correct demodulated symbol.
1. A method, in a receiver, for demodulating a modulated symbol, the method comprising:
receiving, in a correlator, the modulated symbol;
the correlator generating a plurality of correlation values from the received modulated signal and providing the plurality of correlation values to a phase-assisted demodulator;
the phase-assisted demodulator selecting at least two of the plurality of correlation values based on magnitude information of the plurality of correlation values;
the phase-assisted demodulator selecting one of the at least two of the plurality of correlation values based on at least one of magnitude information or phase information of the at least two plurality of correlation values and providing the selected one of the at least two of the plurality of correlation values to a slicer, wherein selecting the one of the at least two of the plurality of correlation values comprises:
when the at least two of the plurality of correlation values are within a predetermined range of each other, selecting the one of the at least two of the plurality of correlation values based on relative phase information of the at least two of the plurality of correlation values; and
the slicer using the selected one of the at least two of the plurality of correlation values and a corresponding index of the selected one of the at least two of the plurality of correlation values to provide a demodulated symbol corresponding to the received modulated symbol at an output of the receiver.
2. The method of claim 1 , wherein the predetermined range comprises 5%.
3. The method of claim 1 , wherein selecting the one of the at least two of the plurality of correlation values further comprises:
when the at least two of the plurality of correlation values are not within the predetermined range of each other, selecting the one of the at least two of the plurality of correlation values having a larger magnitude.
4. A method, in a receiver, for demodulating a modulated symbol, the method comprising:
receiving, in a correlator, the modulated symbol;
the correlator generating a plurality of correlation values from the received modulated signal and providing the plurality of correlation values to a phase-assisted demodulator;
the phase-assisted demodulator selecting at least two of the plurality of correlation values based on magnitude information of the plurality of correlation values, wherein selecting at least two of the plurality of correlation values comprises:
selecting a first correlation value of the plurality of correlation values having a largest magnitude; and
selecting a second correlation value of the plurality of correlation values having a second largest magnitude;
the phase-assisted demodulator selecting one of the at least two of the plurality of correlation values based on at least one of magnitude information or phase information of the at least two plurality of correlation values and providing the selected one of the at least two of the plurality of correlation values to a slicer, wherein selecting one of the at least two of the plurality of correlation values comprises:
if a magnitude of the first correlation value is within a predetermined range of a magnitude of the second correlation value, selecting the one of the at least two of the plurality of correlation values based on which one of the first correlation value or the second correlation value has a phase closest to a π/2 axis; and
the slicer using the selected one of the at least two of the plurality of correlation values and a corresponding index of the selected one of the at least two of the plurality of correlation values to provide a demodulated symbol corresponding to the received modulated symbol at an output of the receiver.
5. The method of claim 1 , wherein the modulated symbol comprises a complementary code keying (CCK) symbol.
6. The method of claim 1 , wherein the modulated symbol comprises a Reed-Muller encoded symbol.
7. A receiver comprising:
an input which receives a modulated signal;
a correlator which generates a plurality of correlation values from the received modulated signal;
a phase-assisted demodulator, coupled to the correlator, which selects one of the plurality of correlation values based on relative magnitude and relative phase information of at least a two of the plurality of correlation values;
an output which provides a demodulated signal, corresponding to the modulated signal, based on the selected one of the plurality of correlation values; and
a slicer, coupled to the phase-assisted demodulator, which receives the selected one of the plurality of correlation values and provides a phase orientation of the selected one of the plurality of correlation values, wherein the demodulated signal is based on the phase orientation and an index of the selected one of the plurality of correlation values.
8. The method of claim 1 , wherein the received modulated signal adheres to an IEEE 802.11b standard.
9. The method of claim 1 , further comprising:
using phase information of the selected one of the at least two of the plurality of correlation values to obtain a phase orientation.
10. The method of claim 9 , wherein using the selected one of the at least two of the plurality of correlation values and the corresponding index to provide a demodulated symbol comprises using the selected one of the at least two of the plurality of correlation values, the corresponding index, and the phase orientation to provide the demodulated symbol.
11. The method of claim 4 , wherein the received modulated signal adheres to an IEEE 802.11b standard.
12. The method of claim 4 , wherein the modulated symbol comprises a complementary code keying (CCK) symbol.
13. The method of claim 4 , wherein the modulated symbol comprises a Reed-Muller encoded symbol.
14. The method of claim 4 , further comprising:
using phase information of the selected one of the at least two of the plurality of correlation values to obtain a phase orientation.
15. The method of claim 14 , wherein using the selected one of the at least two of the plurality of correlation values and the corresponding index to provide a demodulated symbol comprises using the selected one of the at least two of the plurality of correlation values, the corresponding index, and the phase orientation to provide the demodulated symbol.
16. The receiver of claim 7 , wherein, to select the one of the plurality of correlation values, the phase-assisted demodulator selects at least two of the plurality of correlation values based on relative magnitude information of the plurality of correlation values and selects one of the at least two of the plurality of correlation values as the selected one of the plurality of correlation values based on relative phase information of the at least two plurality of correlation values.
17. The receiver of claim 16 , wherein each of the at least two of the plurality of correlation values has a magnitude larger than a magnitude of each correlation value in a remaining portion of the plurality of correlation values.
18. The receiver of claim 17 , wherein the magnitudes of the at least two of the plurality of correlation values are within a predetermined range of each other.
19. The receiver of claim 7 , wherein the modulated signal comprises a complementary code keying (CCK) signal.
20. The receiver of claim 7 , wherein the modulated signal comprises a Reed-Muller encoded signal.