A feedback approach to the steady-state performance of fractionally spaced blind adaptive equalizers

John, D.; Sayed, Ali H.

doi:10.1109/78.815481

Cited by 89 publications

(5 citation statements)

References 27 publications

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“…Without loss of generality, for the 16-QAM signal we derive the steady-state MSE performance of the proposed algorithm without noise using the method proposed in [6]. The key formula for evaluating the steady-state MSE of the adaptive algorithm is […”

Section: Steady-state Mse Performancementioning

confidence: 99%

“…For constant modulus signals, such as 4-QAM, a CMA-based fractionally spaced equalizer (FSE) can achieve a zero steady-state mean-square error (MSE) in noiseless channels. For non-constant modulus signals, such as high-order QAM signals which have been used for a long time in LTE mobile networks [5], it suffers a relatively large misadjustment resulting in a large steady-state MSE [4,6].…”

Section: Introductionmentioning

confidence: 99%

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Low-Complexity Hybrid Adaptive Blind Equalization Algorithm for High-Order QAM Signals

2016

KSII TIIS

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It is well known that the constant modulus algorithm (CMA) presents a large steady-state mean-square error (MSE) for high-order quadrature amplitude modulation (QAM) signals. In this paper, we propose a low-complexity hybrid adaptive blind equalization algorithm, which augments the CMA error function with a novel constellation matched error (CME) term. The most attractive advantage of the proposed algorithm is that it is computationally simpler than concurrent CMA and soft decision-directed (SDD) scheme (CMA+SDD), and modified CMA (MCMA), while the approximation of steady-state MSE of the proposed algorithm is same with CMA+SDD, and lower than MCMA. Extensive simulations demonstrate the performance of the proposed algorithm.

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Section: Steady-state Mse Performancementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Low-Complexity Hybrid Adaptive Blind Equalization Algorithm for High-Order QAM Signals

2016

KSII TIIS

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“…The steady state MSE for the proposed R RECT CA algorithm can be approximated by using equ. (3) and procedure given in [1] and [18]. For an adaptive algorithm of the form…”

Section: Appendix Amentioning

confidence: 99%

“…Clearly the terms Q 1 and Q 2 are identical, so an appropriate expression for steady-state MSE E |e a | 2 . Based on mathematical analysis given in [1] and [18], the error function of R RECT CA with elimination of time index is given as: After some simplification and replacing R 2 RECT with R we have:…”

Section: Appendix Amentioning

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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“…13 which is corresponding to the C R in figure 2. It is clear that the CMA cost function attempts to drive the equalizer output to lie on a circle of radius C R , which is not precise for the high-order QAM signals and the cost function of CMA can not become exactly zero even when the channel is perfectly equalized [8][9][10]. We consider that if the adaptation accord with the modulus which is corresponding to the decision of the equalizer's output signal then it can obtain the faster convergence rate and lower MSE.…”

Section: The Modulus Of High-order Qam Signalsmentioning

confidence: 99%

New Dual-Mode FSE Suitable for High-Order QAM Signals

Gao

Liu

2013

AMR

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In the digital transmission system, constant modulus algorithm (CMA) is a famous blind equalization to overcome the inter-symbol interference without the aid of training sequences. But for the non-constant modulus signals such as higher-order QAM signals, the CMA just achieve moderate steady-state mean square error (MSE). So a new dual-mode fractionally-spaced equalization (FSE) suitable for high-order QAM signals is proposed, which makes full use of the character which is that the high-order QAM signals have the different modulus. This algorithm uses the FSE based on CMA as the basal mode and in the second mode it uses the FSE based on variable modulus algorithm. The simulation results show that compared with CMA the proposed algorithm has faster convergence rate and lower steady-state mean square error.

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A feedback approach to the steady-state performance of fractionally spaced blind adaptive equalizers

Cited by 89 publications

References 27 publications

Low-Complexity Hybrid Adaptive Blind Equalization Algorithm for High-Order QAM Signals

Low-Complexity Hybrid Adaptive Blind Equalization Algorithm for High-Order QAM Signals

Two Novel Blind Equalization Algorithms for Rectangular Quadrature Amplitude Modulation Constellations

New Dual-Mode FSE Suitable for High-Order QAM Signals

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