Spread-OFDM Receiver

• US 20170054480A1
• Filed: 10/17/2016
• Published: 02/23/2017
• Est. Priority Date: 05/14/2002
• Status: Active Grant

• Current Assignee: Genghiscomm Holdings, LLC
• Original Assignee: Genghiscomm Holdings, LLC
• Inventors: Shattil, Steve
• Granted Patent: US 10,211,892 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H04B 1/0003 Software-defined radio [SDR] systems, i.e. systems wherein components typically implemented in hardware, e.g. filters or modulators/demodulators, are implented using software, e.g. by involving an AD or DA conversion stage such that at least part of the signal processing is performed in the digital domain digital baseband systems H04L25/00; digital modulation/demodulation H04L27/00; CDMA H04B1/707; TDMA H04B7/2643; image transmission H04N5/00
• CPC Class Codes: H04B 7/024 Co-operative use of antennas of several sites, e.g. in co-ordinated multipoint or co-operative multiple-input multiple-output [MIMO] systems
• CPC Class Codes: H04B 7/026 Co-operative diversity, e.g. using fixed or mobile stations as relays
• CPC Class Codes: H04B 7/0452 Multi-user MIMO systems
• CPC Class Codes: H04B 7/0456 Selection of precoding matrices or codebooks, e.g. using matrices antenna weighting
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04J 13/0003 Code application, i.e. aspects relating to how codes are applied to form multiplexed channels
• CPC Class Codes: H04J 13/004 Orthogonal
• CPC Class Codes: H04J 13/12 Generation of orthogonal codes
• CPC Class Codes: H04L 27/01 Equalisers baseband equalizers at the transmitter end H04L25/03343; in analogue transmission systems H04B3/04, H04B7/005
• CPC Class Codes: H04L 27/148 using filters, including PLL-type filters
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems
• CPC Class Codes: H04L 27/2602 Signal structure
• CPC Class Codes: H04L 27/2614 Peak power aspects
• CPC Class Codes: H04L 27/2636 with FFT or DFT modulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] transmitter or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/2646 using feedback from receiver for adjusting OFDM transmission parameters, e.g. transmission timing or guard interval length
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 27/26526 with inverse FFT [IFFT] or inverse DFT [IDFT] demodulators, e.g. standard single-carrier frequency-division multiple access [SC-FDMA] receiver or DFT spread orthogonal frequency division multiplexing [DFT-SOFDM]
• CPC Class Codes: H04L 27/26534 Pulse-shaped multi-carrier, i.e. not using rectangular window
• CPC Class Codes: H04L 45/24 Multipath
• CPC Class Codes: H04L 47/10 : Flow control; Congestion control
• CPC Class Codes: H04L 5/0007 : the frequencies being orthogonal, e.g. OFDM(A), DMT
• CPC Class Codes: H04L 5/0021 : in which codes are applied as a frequency-domain sequences, e.g. MC-CDMA
• CPC Class Codes: H04L 5/0023 : Time-frequency-space
• CPC Class Codes: H04L 5/0035 : Resource allocation in a cooperative multipoint environment
• CPC Class Codes: H04L 5/0037 : Inter-user or inter-terminal allocation
• CPC Class Codes: H04L 5/0073 : Allocation arrangements that take into account other cell interferences for intercell interference mitigation or co-ordination in orthogonal multiplex systems H04J11/005
• CPC Class Codes: H04W 72/046 : the resource being in the space domain, e.g. beams
• CPC Class Codes: H04W 84/18 : Self-organising networks, e.g. ad-hoc networks or sensor networks

Abstract

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.

Claims

1. A receiver, comprising:

an Orthogonal Frequency Division Multiplexing (OFDM) demodulator configured 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 discrete Fourier transform (DFT)-based despreader 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.

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 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 discrete Fourier transform (DFT)-based despreader configured 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;

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 discrete Fourier transform (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 to shape the spread-OFDM signal into a plurality of uniformly spaced pulse waveforms modulated with the original data symbols.

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;

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 discrete Fourier transform (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.