The objective of this work is to reconstruct high quality gray-level images from bilevel halftone images. We develop optimal inverse halftoning methods for several commonly used halftone techniques, which include dispersed-dot ordered dither, clustered-dot ordered dither, and error diffusion. At first, the least-mean-square (LMS) adaptive filtering algorithm is applied in the training of invers...

We examine codes, over the additive Gaussian noise channel, designed for reliable communication at some specific signal-to-noise ratio (SNR) and constrained by the permitted minimum mean-square error (MMSE) at lower SNRs. The maximum possible rate is below point-to-point capacity, and hence these are non-optimal codes (alternatively referred to as “bad” codes). We show that the maximum possible...

For the first time it is here shown that Symbolby-Symbol Maximum A Posteriori (SbS-MAP) receivers are able to generate Non-Linear Minimum Mean Square Error (NL-MMSE) estimates of the transmitted symbols.

Multiple Input Multiple Output-Orthogonal Frequency Division Multiplexing (MIMO-OFDM) systems play a vital role in the channel estimation. The wireless channel suffers from impairments like fading and interference. Technologies that achieved above requirements are Multiple Input Multiple Output (MIMO) and Orthogonal Frequency Division Multiplexing (OFDM). Channel impairments must be mitigated a...

In wireless communication system, MIMO-OFDM has been proposed as an efficient technique for providing high date rates, low power consuming and very efficient in 3G and 4G technologies. MultipleInput Multiple-Output (MIMO) & Orthogonal Frequency-Division Multiplexing (OFDM) systems have a assuring ability to increase the capacity and performance with acceptable Bit Error Rate (BER) proportionall...

The Fractional Fourier Transform (FrFT) performs better interference suppression than the fast Fourier Transform (FFT) when the signal-of-interest (SOI) or interference is nonstationary. Minimum mean-square error (MMSE) based filtering in the FrFT domain provides additional benefit in interference suppression in non-stationary environments. However, MMSE filtering requires computational covaria...

The use of frequency-domain equalization (FDE) based on minimum mean square error (MMSE) criterion can significantly improve the downlink bit error rate (BER) performances of DSand MCCDMA in a frequency-selective fading channel. However, the uplink BER performance degrades due to a strong multi-user interference (MUI). In this paper, we propose frequency-interleaved spread spectrum (SS) using M...

The sparse synthesis model for signals has become very popular in the last decade, leading to improved performance in many signal processing applications. This model assumes that a signal may be described as a linear combination of few columns (atoms) of a given synthesis matrix (dictionary). The Co-Sparse Analysis model is a recently introduced counterpart, whereby signals are assumed to be or...

A mathematical programming technique developed recently that optimizes multiple correlated characteristics is the Multivariate Mean Square Error (MMSE). The MMSE approach has obtained noteworthy results, by avoiding the production of inappropriate optimal points that can occur when a method fails to take into account a correlation structure. Where the MMSE approach is deficient, however, is in ...

This chapter considers low-complexity detection in hybrid Direct-Sequence Time-Hopping (DS-TH) Ultrawide Bandwidth (UWB) systems. A range of Minimum Mean-Square Error (MMSE) assisted Multiuser Detection (MUD) schemes are comparatively investigated with emphasis on the low-complexity adaptive MMSE-MUDs, which are free from channel estimation. In this contribution, three types of adaptive MUDs ar...