Per-bin DFE for advanced OQAM-based multi-carrier wireless data transmission systems
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 Orthogonal Frequency Division Multiplication-(OFDM) and (Orthogonal Quadrature Amplitude Modulation (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.
1. A multi-carrier data transmission receiver comprising:
a subchannel demodulator arranged to demodulate one of a plurality of subchannels in a multi-carrier modulated data transmission system;
a subchannel equalizer coupled to the subchannel demodulator and comprising a cascade of a feed-forward finite impulse response (FIR) filter with a feed-back finite impulse response (FIR) filter, the feed-back FIR filter receiving and processing a currently decided symbol in the subchannel;
a second subchannel demodulator arranged to demodulate a second one of the plurality of subchannels in a multi-carrier modulated data transmission system;
a second subchannel equalizer coupled to the second subchannel demodulator and comprising a cascade of a feed-forward finite impulse response (FIR) filter with a feed-back finite impulse response (FIR) filter, the feed-back FIR filter receiving and processing a currently decided symbol in the subchannel;
at least two pulse amplitude modulation (PAM) slicers;
a real extractor; and
an imaginary extractor;
wherein the real and imaginary extractors receive data from the feed-forward finite impulse response (FIR) filter and output data to the PAM slicers; and
wherein data from the PAM slicers is provided to the feed-back finite impulse response (FIR) filter.
2. A multi-carrier data transmission receiver comprising:
a plurality of subchannel demodulators, each arranged to demodulate one of a plurality of subchannels in a multi-carrier modulated data transmission system;
a plurality of subchannel equalizers, each coupled to a corresponding subchannel demodulator, and each comprising a cascade of a feed-forward finite impulse response (FIR) filter with at least one feed-back finite impulse response (FIR) filter, the feed-back FIR filter receiving and processing a currently decided symbol in the subchannel;
at least two pulse amplitude modulation (PAM) slicers;
a real extractor; and
an imaginary extractor;
wherein the real and imaginary extractors receive data from the feed-forward finite impulse response (FIR) filter and output data to the PAM slicers; and
wherein data from the PAM slicers is provided to the at least one feed-back finite impulse response (FIR) filter.
3. The multi-carrier transmission receiver of claim 1 wherein at least one of the subchannel equalizers further comprises at least one additional feed-back finite impulse response (FIR) filter arranged to receive and process currently decided symbols from another one of the plurality of subchannels.
4. The multi-carrier transmission receiver of claim 1 wherein at least one of the subchannel equalizers further comprises an interpolator which interpolates the currently decided symbol before the feed-back FIR filter processes the currently decided symbol.
5. The multi-carrier transmission receiver of claim 1 wherein coefficients of the feed-forward finite impulse response (FIR) filter and the feed-back finite impulse response (FIR) filter are adapted using one of a recursive least square (RLS) and least mean square (LMS) method.
6. The multi-carrier transmission receiver of claim 1 wherein the feed-forward finite impulse response (FIR) filter has a per-subchannel dual automatic equalizer structure.
7. The multi-carrier transmission receiver of claim 2 wherein the subchannel equalizers further comprise at least one additional feed-back finite impulse response (FIR) filter, the additional feed-back FIR filter arranged to receive and process currently decided symbols from another one of said plurality of subchannels.
8. The multi-carrier transmission receiver of claim 2 wherein the feed-forward finite impulse response (FIR) filters have a per-subchannel dual automatic equalizer structure.
9. The multi-carrier transmission receiver claimed in one of claims 1 or 2 wherein the multi-carrier modulated data transmission system has spectrally shaped and overlapped subchannels.
10. The multi-carrier transmission receiver claimed in one of claims 1 or 2 wherein the multi-carrier modulated data transmission system is an orthogonal quadrature amplitude modulation (OQAM)-based system.
11. A multi-carrier transmission receiver comprising:
a subchannel demodulator arranged to demodulate one of a plurality of subchannels in a multi-carrier modulated data transmission system;
a subchannel equalizer coupled to the subchannel demodulator and comprising a cascade of a feed-forward finite impulse response (FIR) filter with a feed-back finite impulse response (FIR) filter, the feed-back FIR filter receiving and processing a currently decided symbol in the subchannel;
at least two pulse amplitude modulation (PAM) slicers;
a real extractor; and
an imaginary extractor;
wherein the real and imaginary extractors receive data from the feed-forward finite impulse response (FIR) filter and output data to the PAM slicers; and
wherein data from the PAM slicers is provided to the feed-back finite impulse response (FIR) filter.