A dual-mode technique for improved blind equalization for QAM signals

He, Liang; Amin, Moeness G.

doi:10.1109/lsp.2002.806699

Cited by 28 publications

(1 citation statement)

References 8 publications

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“…Rigorous work has been done to blindly equalize the distortion in communication channels resulting in various schemes. These schemes include Constant Modulus Algorithm (CMA) [2], the Multimodulus Algorithm (MMA) [3] also presented with the name modified constant modulus algorithm [4] and their several variants [5], [6]. Recently, Thaiupathump et al [7] have proposed Square Contour Algorithm (SCA) which is based on CMA and Reduced Constellation Algorithm (RCA).…”

Section: Introductionmentioning

confidence: 99%

Two Novel Blind Equalization Algorithms for Rectangular Quadrature Amplitude Modulation Constellations

2016

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Two novel blind equalization techniques for odd bit rectangular quadrature amplitude modulation (RQAM) signaling are proposed in this paper, namely, rectangular contour algorithm (R RECT CA) and improved rectangular contour algorithm (IRCA). The proposed R RECT CA algorithm minimizes the dispersion of constant with respect to a rectangular-shaped zero error contour. The algorithm exploits the geometry of the RQAM to correct phase error within 180 • , thus enhancing the convergence rate while minimizing the equalizer mis-adjustments. On the other hand, the proposed IRCA algorithm employs the estimated output from the decision device into the cost function, thus guiding the equalizer output to reside on multiple zero error rectangular shaped moduli. This method of feeding back the slicer output further reduces the mis-adjustment between the transmitted constellation and the new cost function in an efficient manner, which leads to faster convergence and better intersymbol interference suppression. The proposed algorithms can also work for the square QAM by mere change of only two constellation dependent constants, thus facilitating the implementation in hardware to enable transmission of both even and odd number of bits per symbol based constellations. Steady-state error analysis, MSE, and residual ISI comparison through the simulation results confirm the good performance of the proposed algorithms. Furthermore, the convergence characteristics of the proposed IRCA scheme establish the supremacy of IRCA over R RECT CA, which is its parent algorithm.INDEX TERMS Blind equalization, quadrature amplitude modulation (QAM), rectangular QAM, cross QAM, mean square error (MSE), inter symbol interference (ISI).

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Section: Introductionmentioning

confidence: 99%

Two Novel Blind Equalization Algorithms for Rectangular Quadrature Amplitude Modulation Constellations

2016

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Robust Constant Modulus Algorithms

2018

Simplified Robust Adaptive Detection and Beamforming for Wireless Communications

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Feedforward neural network for blind equalization with PSK signals

Pandey

2005

Neural Comput & Applic

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Most of the cost functions used for blind equalization are nonconvex and nonlinear functions of tap weights, when implemented using linear transversal filter structures. Therefore, a blind equalization scheme with a nonlinear structure that can form nonconvex decision regions is desirable. The efficacy of complexvalued feedforward neural networks for blind equalization of linear and nonlinear communication channels has been confirmed by many studies. In this paper we present a complex valued neural network for blind equalization with M-ary phase shift keying (PSK) signals. The complex nonlinear activation functions used in the neural network are especially defined for handling the M-ary PSK signals. The training algorithm based on constant modulus algorithm (CMA) cost function is derived. The improved performance of the proposed neural network in both, stationary and nonstationary environments, is confirmed through computer simulations.

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A dual-mode technique for improved blind equalization for QAM signals

Cited by 28 publications

References 8 publications

Two Novel Blind Equalization Algorithms for Rectangular Quadrature Amplitude Modulation Constellations

Two Novel Blind Equalization Algorithms for Rectangular Quadrature Amplitude Modulation Constellations

Robust Constant Modulus Algorithms

Feedforward neural network for blind equalization with PSK signals

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