Wireless communications device having waveform banks with frequency offset and related methods
View Patent ↗A wireless communications device includes a receiver, and a demodulator coupled downstream from the receiver and configured to use a continuous phase modulation (CPM) waveform to non-coherently demodulate a received signal. The demodulator is configured to generate waveform banks, each waveform bank having a respective different frequency offset associated therewith, determine a correlation output metric for each waveform bank, select a waveform bank for demodulating the received signal based upon the correlation output metrics of the waveform banks, and demodulate the received signal using the selected waveform bank and the associated frequency offset.
1. A wireless communications device comprising:
a receiver; and
a demodulator coupled downstream from said receiver and configured to use a continuous phase modulation (CPM) waveform to non-coherently demodulate a received signal by at least
generating a plurality of waveform banks, each waveform bank having a respective different frequency offset associated therewith,
determining a correlation output metric for each waveform bank,
selecting a waveform bank for demodulating the received signal based upon the correlation output metrics of the plurality of waveform banks, and
demodulating the received signal using the selected waveform bank and the associated frequency offset.
2. The wireless communications device of claim 1 wherein said demodulator is configured to generate each waveform bank based upon a subset of a CPM trellis structure spanning a plurality of symbols and a plurality of transition paths which end in a same final state.
3. The wireless communications device of claim 2 wherein said demodulator is configured to generate a correlation value for each transition path in the subset of the CPM trellis structure.
4. The wireless communications device of claim 1 wherein said demodulator is configured to demodulate a middle symbol in time, the middle symbol in time generating a respective correlation value and being determined based upon a threshold.
5. The wireless communications device of claim 3 wherein said demodulator is configured to determine the correlation output metric for each waveform bank based upon the correlation values therein.
6. The wireless communications device of claim 2 wherein said demodulator is configured to generate each waveform bank comprising a plurality of potential waveforms spanning multiple symbols.
7. The wireless communications device of claim 6 wherein said demodulator generates each waveform bank to span the multiple symbols based upon respective waveform states and the CPM trellis structure.
8. The wireless communications device of claim 1 wherein said demodulator is configured to determine the correlation output metric for each waveform bank based an average value of at least one of minimum and maximum correlation values therein.
9. The wireless communications device of claim 1 wherein said demodulator is configured to demodulate the received signal using a 4-ary version Minimum-shift keying (MSK) modulation.
10. A wireless communications device comprising:
a receiver; and
a demodulator coupled downstream from said receiver and configured to non-coherently demodulate a received continuous phase modulation (CPM) signal by at least
generating a plurality of waveform banks based upon a subset of a CPM trellis structure spanning a plurality of symbols and a plurality of transition paths which end in a same final state, each waveform bank having a respective different frequency offset associated therewith,
determine a plurality of correlation values for each waveform bank,
determining a correlation output metric for each waveform bank based upon the plurality of correlation values,
selecting a waveform bank for demodulating the received CPM signal based upon the correlation output metrics of the plurality of waveform banks, and
demodulating the received CPM signal using the selected waveform bank and the associated frequency offset.
11. The wireless communications device of claim 10 wherein said demodulator is configured to generate the plurality of transition paths, the plurality of transition paths ending in a same final state.
12. The wireless communications device of claim 11 wherein said demodulator is configured to generate each correlation value respectively for each transition path in the subset of the CPM trellis structure.
13. The wireless communications device of claim 10 wherein said demodulator is configured to demodulate a middle symbol in time, the middle symbol in time generating a maximum or minimum correlation value.
14. The wireless communications device of claim 10 wherein said demodulator is configured to generate each waveform bank comprising a plurality of potential waveforms spanning multiple symbols.
15. The wireless communications device of claim 14 wherein said demodulator generates each waveform bank to span the multiple symbols based upon respective waveform states and the CPM trellis structure.
16. The wireless communications device of claim 10 wherein said demodulator is configured to determine the correlation output metric for each waveform bank based upon an average value of at least one of minimum and maximum correlation values therein.
17. A method of non-coherently demodulating a received signal having a continuous phase modulation (CPM) waveform with a wireless communications device comprising a demodulator coupled downstream from a receiver, the method comprising:
using the demodulator to generate a plurality of waveform banks, each waveform bank having a respective different frequency offset associated therewith;
using the demodulator to determine a correlation output metric for each waveform bank;
using the demodulator to select a waveform bank for demodulating the received signal based upon the correlation output metrics of the plurality of waveform banks; and
using the demodulator to demodulate the received signal using the selected waveform bank and the associated frequency offset.
18. The method of claim 17 further comprising using the demodulator to generate each waveform bank based upon a subset of a CPM trellis structure spanning a plurality of symbols and a plurality of transition paths which end in a same final state.
19. The method of claim 18 further comprising using the demodulator to generate a correlation value for each transition path in the subset of the CPM trellis structure.
20. The method of claim 17 further comprising using the demodulator to demodulate a middle symbol in time, the middle symbol in time generating a respective correlation value and being determined based upon a threshold.
21. The method of claim 19 further comprising using the demodulator to determine the correlation output metric for each waveform bank based upon the correlation values therein.
22. The method of claim 18 further comprising using the demodulator to generate each waveform bank comprising a plurality of potential waveforms spanning multiple symbols.
23. The method of claim 22 further comprising using the demodulator to generate each waveform bank to span the multiple symbols based upon respective waveform states and the CPM trellis structure.
24. The method of claim 17 further comprising using the demodulator to determine the correlation output metric for each waveform bank based upon an average value of at least one of minimum and maximum correlation values therein.
25. The method of claim 17 further comprising using the demodulator to demodulate the received signal using a 4-ary version Minimum-shift keying (MSK) modulation.