Frequency-division multiplexing system and method for communication having enhanced reliability in fading environments

• US 20040228271A1
• Filed: 05/14/2003
• Published: 11/18/2004
• Est. Priority Date: 05/14/2003
• Status: Active Grant

• Current Assignee: Alcatel-Lucent USA, Inc. (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Marzetta, Thomas L.
• Granted Patent: US 7,508,808 B2
• Time in Patent Office: Days
• US Class Current: 370/210
• CPC Class Codes: H04L 1/0618 Space-time coding
• CPC Class Codes: H04L 27/2601 Multicarrier modulation systems

Abstract

Frequency-division multiplexing and demultiplexing systems and methods for use with M transmit and N receive antennas, M equaling at least two. In one embodiment, a frequency-division multiplexing system includes: (1) a differential modulator that generates M×M unitary space-frequency signals from incoming message bits and (2) a time-frequency transformer, coupled to the differential modulator, that transforms the M×M space-frequency signals into space-time transmit signals for the M transmit antennas.

Claims

1. A frequency-division multiplexing system for use with M transmit antennas and N receive antennas, M equaling at least two, comprising:

a differential modulator that generates M×

M unitary space-frequency signals from incoming message bits; and

a time-frequency transformer, coupled to said differential modulator, that transforms said M×

M unitary space-frequency signals into space-time transmit signals for said M transmit antennas.

2. The system as recited in claim 1 wherein said differential modulator is a differential OFDM modulator.

3. The system as recited in claim 1 wherein said differential modulator is a differential Cayley modulator.

4. The system as recited in claim 1 wherein said time-frequency transformer applies an Inverse Fast Fourier Transform to said M×

M unitary space-frequency signals.

5. The system as recited in claim 1 wherein said space-time transmit signals include a guard interval.

6. The system as recited in claim 1 wherein said M×

M unitary space-frequency signals is generated and said M×

M unitary space-frequency signals are transformed within a single OFDM symbol interval.

7. A frequency-division multiplexing method for use with M transmit antennas and N receive antennas, M equaling at least two, comprising:

generating M×

M unitary space-frequency signals from incoming message bits; and

transforming said M×

M unitary space-frequency signals into space-time transmit signals for said M transmit antennas.

8. The method as recited in claim 7 wherein said generating is carried out by a differential OFDM modulator.

9. The method as recited in claim 7 wherein said generating is carried out by a differential Cayley modulator.

10. The method as recited in claim 7 wherein said transforming comprises applying an Inverse Fast Fourier Transform to said M×

M unitary space-frequency signals.

11. The method as recited in claim 7 wherein said space-time transmit signals include a guard interval.

12. The method as recited in claim 7 wherein said method is carried out within a single OFDM symbol interval.

13. A frequency-division demultiplexing system for use with M transmit antennas and N receive antennas, M equaling at least two, comprising:

a time-frequency transformer that transforms space-time receive signals from said N receive antennas into M×

N space-frequency signals; and

a differential demodulator, coupled to said time-frequency transformer, that generates outgoing message bits from said M×

N space-frequency signals.

14. The system as recited in claim 13 wherein said differential demodulator is a differential OFDM demodulator.

15. The system as recited in claim 13 wherein said differential demodulator is a differential Cayley demodulator.

16. The system as recited in claim 13 wherein said time-frequency transformer applies a Fast Fourier Transform to said space-time receive signals.

17. The system as recited in claim 13 wherein said space-time transmit signals include a guard interval.

18. The system as recited in claim 13 wherein said M×

M unitary space-frequency signals is generated and said M×

M unitary space-frequency signals are transformed within a single OFDM symbol interval.

19. A frequency-division demultiplexing method for use with M transmit antennas and N receive antennas, M equaling at least two, comprising:

transforming space-time receive signals from said N receive antennas into M×

N space-frequency signals; and

generating outgoing message bits from said M×

N unitary space-frequency signals.

20. The method as recited in claim 19 wherein said transforming is carried out by a differential OFDM demodulator.

21. The method as recited in claim 19 wherein said transforming is carried out by a differential Cayley demodulator.

22. The method as recited in claim 19 wherein said transforming comprises applying a Fast Fourier Transform to said space-time receive signals.

23. The method as recited in claim 19 wherein said space-time receive signals include a guard interval.

24. The method as recited in claim 19 wherein said method is carried out within a single OFDM symbol interval.