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A cooperative system may have both timing errors and multiple carrier frequency offsets (CFOs). To combat timing errors, space-frequency (SF) coded OFDM systems have been recently proposed for cooperative communications to achieve both full cooperative and full multipath diversities without time synchronization requirement. In this paper, we study the effect of multiple CFOs from relay nodes on a...
In most real-world situations, a single microphone is insufficient for the characterization of an entire auditory scene. This often occurs in places such as office environments which consist of several interconnected spaces that are at least partially acoustically isolated from one another. To this end, we extend our previous work on segmentation of natural sounds to perform scene characterization...
Cooperation can improve the performance of spectrum sensing. However, the sensing overhead is generally increasing with the number of cooperating users as more data needs to be reported to the fusion center. Most existing works assume a general time frame structure in which spectrum observing and sensing results reporting are conducted sequentially. We argue that this frame structure is inefficient,...
DS-CDMA in the modern civil and military communications is widely used. Due to its low power spectral density, the DS-CDMA signal always floods in the background noise, bringing difficulties to the signalpsilas reconnaissance. Therefore, DS-CDMA signal detection has attracted attention of researchers. Because the fourth-order moment chip is blind to the arbitrary Gaussian noise, the detection method...
Base station cooperation has been identified as promising features of reducing cell interference and increasing capacity. Main cooperative strategy is the information exchange processed by a cooperative base station or control center, However, the set up of communication procedure was the premise of the application of any cooperation strategy. Measurement, decision, and realization processing are...
Multiuser diversity can significantly improve wireless system performance by exploiting the feedback information that conveys the channel quality. In multiple input-multiple output and orthogonal frequency division multiplexing (MIMO-OFDM) systems, the per subcarrier on per antenna feedback induces a substantial amount of feedback overload and requires high computational complexity. This paper addresses...
Coded Cooperation (CC) is a promising user cooperation scheme. In this paper, we propose a novel network- coding-based coded cooperation scheme. When a user decodes its partner's information correctly in the first frame, it transmits the combination of the partner's parity bits and its own parity bits through network coding in the second frame. This is distinct from the classical scheme, where the...
We present a decision-directed tracking approach to doubly-selective channel estimation exploiting the complex exponential basis expansion model (CE-BEM). The time-varying nature of the channel is well captured by the CE-BEM while the time-variations of the (unknown) BEM coefficients are likely much slower than those of the channel. We track the BEM coefficients via the exponentially-weighted recursive...
In this paper, we propose a novel radius control strategy for sphere decoding referred to as inter search radius control that provides further improvement of the computational complexity with minimal extra cost and negligible performance penalty. The proposed method focuses on the sphere radius control strategy when a candidate lattice point is found. For this purpose, the dynamic radius update strategy...
In this paper, we propose a method for predicting traffic values from spectrum measurements. The purpose is to obtain traffic information from the wireless environment for making informed decisions in order to balance traffic loads. We propose a supervised prediction scheme trained by real measurements, such that the method adapts to new radio contexts for new measurements. As a first step, features...
Localizing micro cracks in critical components is crucial in the field of continuous structural health monitoring. In this paper, we utilize several signal processing and machine learning techniques such as hierarchical clustering and support vector machines (SVM) to process multisensor acoustic emission (AE) data generated by the inception and propagation of cracks. We present preliminary laboratory...
We use the theory and algorithms developed for so-called shift-invariant spaces to develop a novel distributed architecture for sampling and reconstructing non-bandlimited fields in wireless sensor networks. Our scheme groups neighboring sensors into clusters that locally perform highly accurate field reconstruction with limited communication overhead. The overall complexity of our method scales only...
This paper deals with the detection of a continuous random process described by an Ornstein-Uhlenbeck (O-U) stochastic differential equation. Randomly spaced sensors or equivalently a random time sampler which deliver noisy samples of the process are used for this detection. Two types of tests are considered: either H0 refers to the presence of the noisy O-U process or H0 refers to the sole presence...
The outage probability is a fundamental performance metric, which has been widely investigated in the literature. In this paper, we develop a general method to compute the outage given the moment generating function (MGF). When computing the outage using the MGF, integration along the standard Bromwich contour suffers from a loss of accuracy due to oscillatory nature of the integrand. One can address...
Minimizing the rank of a matrix X over certain constraints arises in diverse areas such as machine learning, control system and is known to be computationally NP-hard. In this paper, a new simple and efficient algorithm for solving this rank minimization problem with linear constraints is proposed. By using gradient projection method to optimize S while consecutively updating matrices U and V (where...
In this paper we consider the problem of sampling far below the Nyquist rate signals that are sparse linear superpositions of shifts of a known, potentially wide-band, pulse. This signal model is key for applications such as Ultra Wide Band (UWB) communications or neural signal processing. Following the recently proposed Compressed Sensing methodology, we study several acquisition strategies and show...
Selection relaying is a promising technique for practical implementation of cooperative systems with multiple relays. However, to select the best relay, globe channel knowledge is required at the selecting entity. In this paper, we consider the relay selection problem in dual-hop amplify-and-forward (AF) communication systems with partial channel state information (CSI). We present relay selection...
In this paper, we solve the problem of detecting the entries of a sparse finite-alphabet signal from a limited amount of data, for instance obtained by compressive sampling. While existing methods either rely on the sparsity property, the finite-alphabet property, or none of those properties to solve the under-determined system of linear equations, we capitalize on both the sparsity and the finite-alphabet...
We investigate the design of MIMO linear precoders for multiuser broadcast channels under signal leakage constraints. This power leakage constraints reflect both an important security consideration and the need for interference suppression at receivers. Defining a convex optimization problem, we propose two sequential semi-definite program algorithms. In principle, our algorithms exploit both spatial...
Cooperative networking as a means of creating spatial diversity is used in order to mitigate the adverse effect of fading in a wireless channel and increase reliability of communications. We investigate signal-to-noise ratio (SNR) gain in wireless cooperative networks. We show that the differential SNR gain in the high data rate regime, which we refer to as SNR gain exponent zetainfin, is independent...
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