This paper compares performance of finite impulse response (FIR) adaptive linear equalizers based on the recursive least-squares (RLS) and least mean square (LMS) algorithms in nonstationary uncorrelated scattering wireless channels. Simulation results, in terms of steady-state mean-square estimation error (MSE) and average bit-error rate (BER) metrics, are found for the frequency-selective Ray...

Parallel architectures for decision-directed adaptive recursive least-squares (RLS) equalizers based on a QR-decomposition (QRD) using square-root free Givens-rotations are derived that allow very high throughput for broadband applications. We apply an algorithmic optimization that leads to the use of additional fast adder trees together with a re-timing of the required arithmetic components to...

This paper presents a cost-effective test methodology for adaptive equalizers which follow the digitally-assisted analog design style. By observing the states in the digital adaptation engine during or after the adaptation process in response to the test stimulus, the health of the adaptive equalizer can be determined. We propose two different types of signatures, namely static and dynamic sign...

Several widely linear equalization algorithms utilizing the rotationally variant nature of the received signals are presented in this paper to combat the detrimental effect of intersymbol interference (ISI) introduced by frequency selective channels. Their adaptive implementations and application to the timereversal space-time coded (TR-STBC) system are also considered. In addition, a widely li...

This paper presents an innovative Non-Linear Receiver (NLR) for the high density optical channel. This receiver is based on the combination of Maximum Likelihood Sequence Estimation (MLSE) and nonlinear Inter-Symbol Interference (ISI) cancellation. For the nonlinear channel description a suitable model based on the Volterra series has been adopted. Simulation results show that the proposed NLR ...

A Mutually-Orthogonal Usercode-Receiver (AMOUR) system was recently proposed to guarantee identifiability of transmitted symbols irrespective of channel nulls in addition to offering deterministic MUI elimination and low complexity transceivers. Motivated by the desire to equip the AMOUR with added flexibility, we develop in this paper a Vandermonde–Lagrange AMOUR system that achieves the same ...

This paper describes a new adaptive blind equalization algorithm based on a truly IIR structure that enables the correction of ISI over severely distorted channels. The recursive feedback filter is in lattice form to allow an easy monitoring of the filter stability. During blind training, the adaptation of the equalizer is carried out via the usual stochastic gradient algorithm by minimizing th...

In this paper, energy efficient VLSI architectures for linear turbo equalization are studied. Linear turbo equalizers exhibit dramatic bit error rate (BER) improvement over conventional equalizers by enabling a form of joint equalization and decoding in which soft information is iteratively exchanged between the equalizer and decoder. However, turbo equalizers can be computationally complex and...

Low-complexity soft-in soft-out (SISO) equalizers based on time-varying linear filters and soft inter-symbol interference cancellation are known to be a viable alternative to the optimal trellis-based SISO equalizers when used in receivers based on iterative equalization and decoding. In particular, when the signal constellation is large and/or the channel impulse response is long, the computat...

This paper performs a detailed, multi-faceted analysis of key challenges and common design caveats related to the development efficient neural networks (NN) based nonlinear channel equalizers in coherent optical communication systems. The goal this study is guide researchers engineers working field. We start by clarifying metrics used evaluate equalizers’ performance, relating them loss functio...