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We present a new precoding model for closed-loop multiple-antenna systems based on a tensor signal modeling and transmit antenna selection. The precoder is modeled as a third-order tensor and decomposed as a function of (i) an antenna selection matrix determining the allocation of data streams to transmit antennas and (ii) an orthogonal code matrix that spreads the data streams across time-slots....
This work presents a novel initial ranging scheme for orthogonal frequency-division multiple-access networks. Users that intend to establish a communication link with the base station (BS) are normally misaligned both in time and frequency and the goal is to jointly estimate their timing errors and carrier frequency offsets with respect to the BS local references. This is accomplished with affordable...
In this paper we propose a novel M-ary biorthogonal pulse shape modulation scheme for an Impulse radio ultra wideband (IR-UWB) system transmitting over lognormal fading channels. Our proposed modulation scheme enables different transmission rates for a fixed number of orthogonal pulses M/2, while the symbol period Ts is constant. In our transmission scheme information bits are mapped into N pulses...
This paper describes a novel on-demand receive filter in an UMTS terminal. The receive filter is the first function after the Analog-to-Digital converter and is for that reason one of the most computation intensive parts in a receiver. The proposed filter architecture measures the out-of-band interference and calculates the required attenuation, which is used to select the appropriate filter. To assess...
This paper considers the uniformly minimum variance unbiased estimator of a probability p based on inverse binomial sampling. It is shown that the confidence associated to intervals of the form [p/mu2, pmu1], mu1, mu2 > 1 has an asymptotic value as p rarr 0. Furthermore, the confidence for p isin (0, 1) arbitrary is guaranteed to exceed this asymptotic value if mu1, mu2 satisfy certain conditions...
This article describes a new distributed blind equalization algorithm based on particle filters suitable for CDMA systems operating on frequency-selective channels. The proposed approach processes the signal received by multiple receivers in a non-centralized fashion, determining approximately optimal estimates (MAP) of the transmitted symbols, which minimizes the expected error rate. The described...
Consider the linear Wiener receiver for multidimensional signals. Such a receiver is frequently encountered in wireless communications and in array processing, and the Signal to noise ratio (SNR) at its output is a popular performance index. The SNR can be modeled as a random quadratic form and in order to study this quadratic form, one can rely on well-know results in Random Matrix Theory, if one...
Particle filtering has been successfully used to approximate the fixed-lag or fixed-interval smoothing distributions in digital communication and to perform approximate maximum likelihood inference. Because the state-space is finite, it is possible at each step to consider all the offsprings (path) of any given particle. Because each particle has typically several possible offsprings, the population...
Distributed estimation is a major feature in wireless sensor networks (WSNs). Recently, hard quantized observations based on sign of innovation (SOI) were used to perform optimal distributed filtering involving thus the SOI Kalman filter (KF)/extended KF (EKF) [1]. In this paper, a SOI-particle filter (SOIPF) is derived to enhance the performance of the distributed estimation procedure. On one hand,...
We use the particle filtering approach to develop a new Bayesian equalizer for turbo equalization under conditions of imperfect estimation of the channel impulse response (CIR) and the noise variance. This new equalizer is derived on the basis of fixed-lag smoothing, using the SIS (Sequential Importance Sampling) methodology to approximate the conditional probability distribution of a block of transmitted...
The distribution of the peak-to-average power ratio (PAPR) for geometric method of PAPR reduction in orthogonal frequency-division multiplexing (OFDM) signals is evaluated in order to analyse the influence of the carrier frequency of adding signal on the PAPR reduction. Assuming that the baseband OFDM signal is characterized as a band-limited complex Gaussian process, we first recall the principle...
This paper considers a DS/CDMA relay system where random spreading sequences are employed at the relays to allow multiple access to the channel between relays and destination. Two different protocols are considered and compared, the difference between them being whether the source remains silent or sends new information symbols during the relaying. For both protocols, we provide a low source power...
In this paper we investigate the information theoretic capacity of the uplink of a cellular system where all base station receivers jointly decode the received signals (ldquohyper-receiverrdquo). Considering a distance depended power-law path loss and a more realistic Rician fading environment, we model a variable cell density network with geographically distributed user terminals. Multiple tiers...
We establish that expectation propagation (EP), under some mild requirements and when properly organized, provides sensors with optimal Bayes estimators during the initialization phase of a large randomly deployed wireless sensor network, regardless of the cost function chosen. We are considering the initialization phase to be the period during which the sensors do not yet know their locations and...
OFDM/OQAM is a multi-carrier modulation scheme that can be considered as an alternative to conventional OFDM with cyclic prefix (CP) for transmission over multi-path fading channels. As it requires no CP, it has the advantage of a theoretically higher spectral efficiency. Furthermore, efficient pulse shaping can also be easily implemented. However, the classical channel estimation methods used for...
In this paper, we propose a semi-blind state-space based receiver that jointly performs channel estimation and data detection in MIMO systems subject to fast frequency-selective fading. To accomplish these two tasks, we first define state equations representing the dynamics of channel and transmitted signals. Then, we obtain the state vector by concatenating the transmitted signals and the channel...
In recent years node localization in wireless sensor networks (WSNs) has attracted much attention due to the increase of usage and applications of WSNs. Many algorithms and techniques for locating sensor nodes have been proposed in the literature. A recent algorithm, which is based on a given set of pairwise distance estimates among nodes and the target, generates a map of node locations. This algorithm,...
In this paper we analyze the impact of quantization on the performance of a discrete-time distributed algorithm aimed at computing the average of an initial set of values in a wireless sensor network. We modify a well-known consensus model and propose a simple scheme where the transmitted data is quantized due to bandwith and/or power constraints. Conversely to existing models that include quantization...
In this paper, we consider the problem of identification of nonlinear communication channels using input-output measurements. The nonlinear channel is structured as a LTI-ZMNL-LTI one, i.e. a zero-memory nonlinearity (ZMNL) sandwiched between two linear time-invariant (LTI) subchannels. Considering Volterra kernels of order higher than two as tensors, we show that such a kernel associated with a LTI-ZMNL-LTI...
In this paper, we are interested in blind identification of single-input multiple-output (SIMO) systems. Using the sparsity property of impulse response, we propose an iterative method which minimizes a cost function based on the lscrp norm. This norm is considered as a good sparsity measure. The simulations show that the proposed method outperforms existing techniques in terms of estimation error...
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