Per-bin DFE for advanced OQAM-based multi-carrier wireless data transmission systems

• US 20030063680A1
• Filed: 02/19/2002
• Published: 04/03/2003
• Est. Priority Date: 09/28/2001
• Status: Active Grant

• Current Assignee: NEC Corporation
• Original Assignee: NEC USA Inc (NEC Corporation)
• Inventors: Popovic, Nenad, Nedic, Slobodan
• Granted Patent: US 7,436,881 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: H04L 2025/03414 Multicarrier
• CPC Class Codes: H04L 2025/03611 Iterative algorithms
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence

Abstract

An Apparatus for non-linear per-bin adaptive equalization in orthogonal multi-carrier data transmission systems with the Nyquist sub-channel spectral shaping and T/2 staggering of in-phase and quadrature components is disclosed. A previously introduced linear equalization embodiments are augmented by up to three, or more decision feed-back filters, to improve performance in presence of narrow-band interference (NBI) in wire-line and wire-less data transmission systems, and to enable exploitation of implicit diversity of multi-path fading channels, both with and without transmitter-end pre-coding. Adaptation properties of per-bin DFE equalization are analyzed by computer simulation for an intermediate number of constituent sub-channels. BER performance comparison between the conventional OFDM and OQAM-based multi-carrier systems of similar modulation/demodulation complexity and transmission latency is provided and the potential advantage of using spectrally well shaped orthogonal sub-channels in wireless applications is demonstrated.

Claims

1. A multi-carrier data transmission system comprising:

a transmitter;

a transmission channel connected to said transmitter; and

a receiver connected to said transmission channel;

wherein the receiver comprises;

a feed-forward FIR filter and

a feed-back FIR filter; and

wherein outputs of the feed-forward FIR filter and feed-back FIR filter are combined.

2. The system as claimed in claim 1, wherein said receiver comprises at least two feed-back FIR filters and

wherein outputs of the feed-forward FIR filter and feed-back FIR filters are combined.

3. The system as claimed in claim 1, wherein said receiver further comprises an interpolator that receives an output from the feed-forward FIR filter and sends an output to the feed-back FIR filter.

wherein outputs of the feed-forward FIR filter and feed-back FIR filters are combined;

and

coefficients of the equalizer filters are adapted using RLS or LMS method.

4. The system as claimed in claim 1, wherein said receiver further comprises:

at least two pulse amplitude modulation slicers; and

real and imaginary extractors;

wherein the real and imaginary extractors receive data from the feed-forward FIR filter and output data to the pulse amplitude modulation slicers; and

wherein data from the pulse amplitude modulation slicers is provided to the feed-back FIR filters.

5. The system as claimed in claim 4, wherein data input to at least one of the pulse amplitude modulation slicers and output from at least one of the pulse amplitude modulation slicers is used to generate an error signal.

6. The system as claimed in one of claims 1, 2, 3, 4 or 5, wherein said multi-carrier data transmission system has spectrally shaped and overlapped sub-channels.

7. The system as claimed in one of claims 1, 2, 3, 4 or 5, wherein said multi-carrier data transmission system is an OQAM-based multi-carrier wireless, or wire-line data transmission system.

8. A multi-carrier data transmission receiver comprising:

a feed-forward FIR filter and

a feed-back FIR filter;

wherein outputs of the feed-forward FIR filter and feed-back FIR filter are combined.

9. The receiver as claimed in claim 8, wherein said receiver comprises at least two feed-back FIR filters and

wherein outputs of the feed-forward FIR filter and feed-back FIR filters are combined.

10. The receiver as claimed in claim 8, wherein said receiver further comprises:

at least two pulse amplitude modulation slicers; and

real and imaginary extractors;

wherein the real and imaginary extractors receive data from the feed-forward FIR filter and output data to the pulse amplitude modulation slicers; and

wherein data from the pulse amplitude modulation slicers is provided to the feed-back FIR filter.

11. The system as claimed in claim 10, wherein data input to at least one of the pulse amplitude modulation slicers and output from at least one of the pulse amplitude modulation slicers is used to generate an error signal for coefficients adaptations.

12. A multi-carrier data transmission system comprising:

a transmitter;

a transmission channel connected to said transmitter; and

a receiver connected to said transmission channel;

wherein the transmitter comprises a feed-back FIR filter;

wherein the receiver comprises a feed-forward FIR filter; and

wherein the transmitter performs pre-coding of a signal prior to outputting the signal to the transmission channel.

13. The system as claimed in claim 12, wherein said receiver further comprises:

at least two pulse amplitude modulation slicers; and

real and imaginary extractors; and

wherein the real and imaginary extractors receive data from the feed-forward FIR filter and output data to the pulse amplitude modulation slicers.

14. The system as claimed in claim 12, wherein said transmitter comprises at least one pre-coding feed-back FIR filters per active sub-channel.

15. A multi-carrier data transmission system comprising:

a transmitter;

a transmission channel connected to said transmitter;

a receiver connected to said transmission channel;

wherein the receiver comprises;

a linear equalizer;

a feed-forward FIR filter that receives an input from the destagered receive filter-bank output;

and

a feed-back FIR filter; and

wherein outputs of the feed-forward FIR filter and feed-back FIR filters are combined.

16. The system as claimed in claim 15, wherein the receiver comprises up to three feed-back FIR filters and

wherein outputs of the feed-forward FIR filter and feed-back FIR filters are combined.

17. The system as claimed in claim 15, wherein said receiver further comprises:

at least two pulse amplitude modulation slicers; and

real and imaginary extractors;

wherein the real and imaginary extractors receive data from the feed-forward FIR filter and output data to the pulse amplitude modulation slicers; and

wherein data from the pulse amplitude modulation slicers is provided to the feed-back FIR filter.

18. The system as claimed in claim 17, wherein data input to at least one of the pulse amplitude modulation slicers and output from at least one of the pulse amplitude modulation slicers is used to generate an error signal.

19. The system as claimed in one of claims 15, 16, 17 or 18, wherein said multi-carrier data transmission system has spectrally shaped and overlapped sub-channels.

20. The system as claimed in one of claims 15, 16, 17 or 18, wherein said multi-carrier data transmission system is an OQAM-based multi-carrier data transmission systems.