The problem of joint blind channel estimation and multiple access interference (MAI) suppression for an asynchronous code-division multiple-access (CDMA) system is studied. A low-complexity sliding-window scheme based on the expectation maximization (EM) algorithm is developed for joint blind maximum a posteriori probability (MAP) multi-user detection (MUD) and stochastic maximum likelihood (ML...

This paper presents a Clustering Based Blind Channel Estimator for a special case of sparse channels – the zero pad channels. The proposed algorithm uses an unsupervised clustering technique for the estimation of data clusters. Clusters labelling is performed by a Hidden Markov Model of the observation sequence appropriately modified to exploit channel sparsity. The algorithm achieves a substan...

In digital communications systems, interleavers are used to stir bits of channel coded data to robust against burst error in noisy channel. However, in non-cooperative context such as signal intelligence system(SIGINT) and spectrum surveillance systems, interleaver may act as encryptor to 3 party listener who has no information about the interleaver parameters used in transmitter. Therefore, bl...

In this paper, we present two novel blind channel estimation algorithms for OFDM systems based upon the knowledge that the modulated and transmitted data are confined to a finite alphabet set. The Minimum Impulse Length (MIL) method exploits the correlations between adjacent subcarrier coefficients caused by time limited impulse responses and shows a very good estimation performance. Unfortunat...

We investigated the feasibility of applying blind equalization to wireless ATM networks. Making use of the information exploited from the wireless ATM cell structure and Medium Access Control(MAC), blind channel estimation together with a Non-linear Data Directed Estimator achieve good equalization performance without transmitting extra preamble. Simulation results are presented for ATM CBR and...

In this paper, we describe methods for computing fractionally spaced blind equalizers directly from second-order statistics of the observations. The equalizers with all possible delays are computed simultaneously, and the one with the best delay is picked by a blind constant modulus index. Our algorithm utilizes the equalizer output whitening property of the blind equalizers, i.e., output white...

This paper is devoted to the analysis of a “semi-blind” estimation framework in which the standard input-output (training sequence based) estimation is enhanced by using the statistical structure of the information sequence. More specifically, we consider the case of a general TDMA frame-based receiver equipped with multiple sensors, and restrict our attention to second-order based subspace met...

We used magnitude estimation to determine preferred datato-display mappings, polarities, and psychophysical scaling functions relating perceptual and conceptual data values to underlying acoustic parameters for blind and visually impaired listeners. We compare the resulting scaling functions to previous findings with sighted participants [1]. The findings have implications for the design of fut...

This paper presents a novel scheme for detection of watermarks embedded in multimedia signals using spread spectrum (SS) techniques. The detection method is centered on using the model that the embedded watermark and the host signal are mutually independent. The proposed detector assumes that the host signal and the watermark obey non-Gaussian distributions. The proposed blind watermark detecto...