US 9,559,875 B2Granted

Blind equalization in a single carrier wideband channel

AssigneeNorthrop Grumman Systems Corporation

InventorsDaniel N. Liu, Michael P. Fitz

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Abstract

A blind equalizer apparatus includes a decision-directed (DD) least mean squares (LMS) blind equalizer. A blind equalizer apparatus includes: a DD LMS blind equalizer, wherein: the blind equalizer uses a finite impulse response filter with tap weights that are adaptively updated using a filter tap update algorithm, wherein blind equalization of one of an in-phase (I) channel and a quadrature (Q) channel is carried out by maximizing the Euclidean distance of binary modulated waveforms, wherein the blind equalizer averages a block to compute an independent phase estimate for a block, wherein the blind equalizer computes an error variable for a block from the phase estimate for the block, wherein the blind equalizer uses the phase estimate and alternating I/Q one dimensional/binary slicing to make a hard decision, and wherein the blind equalizer uses the hard decision to derive an error variable that is used to update the filter tap weights.

Claims18

Dependent claims

A receiver system, comprising:

a decision-directed (DD) least mean squares (LMS) blind equalizer for equalizing a minimum shift keying (MSK) signal in a single carrier channel, the output signal of the DD LMS blind equalizer having, after equalizing approximately 5.11×108 MSK symbols, a non-zero phase offset θ0, the DD LMS equalizer further comprising a finite impulse response filter with tap weights that are adaptively updated using a filter tap update algorithm, the output signal having, after equalizing approximately 5.11×108 MSK symbols, a non-zero carrier frequency offset (CFO) f0, wherein:
the DD LMS blind equalizer averages a block to compute an independent phase estimate for a block,
the DD LMS blind equalizer computes an error variable for a block from the phase estimate for the block,
the DD LMS blind equalizer uses the phase estimate and alternating in-phase/quadrature (I/Q) one dimensional/binary slicing to make a hard decision that does not comprise output of the receiver system, and
operating simultaneously in DD mode and as a blind equalizer, the DD LMS blind equalizer uses the hard decision to derive an error variable that is used to update the filter tap weights of the DD LMS equalizer.

2 more elements

Dependencies are inferred from the claim text.