Spread-OFDM receiver
View Patent ↗In a wireless communication system, a receiver comprises an Orthogonal Frequency Division Multiplexing (OFDM) demodulator configured to demodulate a spread-OFDM signal transmitted from a user equipment (UE) to produce demodulated data symbols corresponding to OFDM subcarriers assigned to the UE. A discrete Fourier transform (DFT)-based despreader is configured to despread the demodulated data symbols to produce estimates of original data symbols, wherein the despreader employs a DFT despreading code corresponding to a DFT spreading code employed by the UE to shape the spread-OFDM signal into a plurality of uniformly spaced pulse waveforms modulated with the original data symbols. A frequency-domain equalizer may be provided to equalize and/or spatial deumultiplex the demodulated data symbols before despreading.
1. A receiver, comprising:
an Orthogonal Frequency Division Multiplexing (OFDM) demodulator configured to perform a first discrete Fourier transform (DFT) to demodulate a spread-OFDM signal transmitted from a user equipment (UE), to produce a plurality of demodulated data symbols corresponding to a plurality of OFDM subcarriers assigned to the UE; and
a DFT-based despreader configured to perform a second DFT to despread the demodulated data symbols to produce estimates of original data symbols, wherein the despreader employs a DFT despreading code corresponding to a DFT spreading code employed by the UE.
2. The receiver recited in claim 1 , further comprising an equalizer coupled between the OFDM demodulator and the DFT-based despreader, configured to perform at least one of frequency-domain equalization and spatial demultiplexing of the plurality of demodulated data symbols.
3. The receiver recited in claim 1 , wherein the DFT-based despreader employs an inverse DFT.
4. The receiver recited in claim 1 , wherein the OFDM demodulator employs a DFT.
5. The receiver recited in claim 1 , wherein the OFDM demodulator is configured to demodulate at least one of reference symbols and user data symbols.
6. The receiver recited in claim 1 , wherein the OFDM demodulator is configured to remove at least one of a cyclic prefix, a postfix, and a guard interval from the spread-OFDM signal before demodulation.
7. The receiver recited in claim 1 , further comprising a pulse-shape filter configured to filter the spread-OFDM signal.
8. The receiver recited in claim 1 , wherein the plurality of OFDM subcarriers comprises at least one of a block of contiguous subcarriers, and a set of non-contiguous subcarriers.
9. A base transceiver station, comprising:
an Orthogonal Frequency Division Multiplexing (OFDM) demodulator configured to perform a first discrete Fourier transform (DFT) to demodulate a spread-OFDM signal transmitted from a user equipment (UE), to produce a plurality of demodulated data symbols corresponding to a plurality of OFDM subcarriers assigned to the UE; and
a DFT-based despreader configured to perform a second DFT to despread the demodulated data symbols to produce despread original data symbols, wherein the despreader employs a DFT despreading code corresponding to a DFT spreading code employed by the UE to reduce peak-to-average power of the spread-OFDM signal.
10. The base transceiver station recited in claim 9 , further comprising a frequency-domain equalizer coupled between the OFDM demodulator and the DFT-based despreader, configured to perform at least one of frequency-domain equalization and spatial demultiplexing of the plurality of demodulated data symbols before despreading by the DFT-based spreader.
11. The base transceiver station recited in claim 9 , wherein the DFT-based despreader employs an inverse DFT.
12. The base transceiver station recited in claim 9 , wherein the OFDM demodulator employs a DFT.
13. The base transceiver station recited in claim 9 , wherein the OFDM demodulator is configured to demodulate at least one of reference symbols and user data symbols.
14. The base transceiver station recited in claim 9 , wherein the OFDM demodulator is configured to remove at least one of a cyclic prefix, a postfix, and a guard interval from the spread-OFDM signal before demodulation.
15. The base transceiver station recited in claim 9 , further comprising a pulse-shape filter configured to filter the spread-OFDM signal.
16. The base transceiver station recited in claim 9 , wherein the plurality of OFDM subcarriers comprises at least one of a block of contiguous subcarriers, and a set of non-contiguous subcarriers.
17. A method, comprising:
demodulating a spread-Orthogonal Frequency Division Multiplexing (OFDM) signal transmitted from a user equipment (UE) to produce a plurality of demodulated data symbols corresponding to a plurality of OFDM subcarriers assigned to the UE, wherein demodulating comprises performing a first discrete Fourier transform (DFT);
providing for at least one of frequency-domain equalization and spatial demultiplexing of the plurality of demodulated data symbols to produce a plurality of equalized symbols; and
performing a second DFT to provide for DFT-based despreading of the equalized symbols to produce estimates of original data symbols, wherein the despreading employs a DFT despreading code corresponding to a DFT spreading code employed by the UE.
18. The method recited in claim 17 , wherein the DFT-based despreading comprises employing an inverse DFT.
19. The method recited in claim 17 , wherein the demodulating employs a DFT.
20. The method recited in claim 17 , wherein the demodulating comprises demodulating at least one of reference symbols and user data symbols.
21. The method recited in claim 17 , further comprising removing at least one of a cyclic prefix, a postfix, and a guard interval from the spread-OFDM signal before the demodulating.
22. The method recited in claim 17 , further comprising pulse-shape filtering the spread-OFDM signal.
23. The method recited in claim 17 , wherein the plurality of OFDM subcarriers comprises at least one of a block of contiguous subcarriers, and a set of non-contiguous subcarriers.
24. An apparatus comprising:
a processor; and
a memory coupled to the processor, the memory including a set of instructions stored therein and executable by the processor to:
perform a first discrete Fourier transform (DFT) to demodulate a spread-Orthogonal Frequency Division Multiplexing (OFDM) signal transmitted from a user equipment (UE) to produce a plurality of demodulated data symbols corresponding to a plurality of OFDM subcarriers assigned to the UE; and
perform a second DFT to provide for DFT-based despreading of the plurality of demodulated data symbols to produce estimates of original data symbols, wherein the despreading employs a DFT despreading code corresponding to a DFT spreading code employed by the UE to reduce peak-to-average power of the spread-OFDM signal.
25. The apparatus recited in claim 24 , further comprising instructions to perform at least one of frequency-domain equalization and spatial demultiplexing of the plurality of demodulated data symbols before the despreading.
26. The apparatus recited in claim 24 , wherein the DFT-based despreading comprises an inverse DFT.
27. The apparatus recited in claim 24 , wherein the instructions to demodulate comprise instructions to employ a DFT.
28. The apparatus recited in claim 24 , wherein the instructions to demodulate comprise instructions to demodulate at least one of reference symbols and user data symbols.
29. The apparatus recited in claim 24 , wherein the memory further comprises instructions to remove at least one of a cyclic prefix, a postfix, and a guard interval from the spread-OFDM signal before demodulating the spread-OFDM signal.
30. The apparatus recited in claim 24 , wherein the memory further comprises instructions to pulse-shape filter the spread-OFDM signal.
31. The apparatus recited in claim 24 , wherein the plurality of OFDM subcarriers comprises at least one of a block of contiguous subcarriers, and a set of non-contiguous subcarriers.