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Cooperative diversity enables single antenna transmitter in a multi-user or relay environment to share the antennas so as to achieve diversity gain. In this work, the cooperative communication system with distributed Alamouti code is investigated, where amplify-and-forward (AF), adaptive decode-and-forward (DF) or hybrid AF/DF are used at the relay, with both Rayleigh fading and path loss effect introduced...
Collaborative sensing in cognitive radio networks can significantly improve the probability of detecting the transmission of primary users. In current collaborative sensing schemes, all collaborative secondary users are assumed to be honest. As a consequence, the system is vulnerable to attacks in which malicious secondary users report false detection results. In this paper, we investigate how to...
This paper presents an analysis of the joint estimation of target location and velocity using multiple-input multiple-output (MIMO) radar. A theorem is formulated on the asymptotic properties of the maximum likelihood (ML) estimate. The joint Cramer-Rao bound (CRB) is calculated for a Rayleigh fluctuating extended target. The mean square error (MSE) of the ML estimate is analyzed for orthogonal Gaussian...
This paper presents a multi-frequency method to increase the number of incoherent sources that can be resolved using multiple signal classification (MUSIC). The method uses coarray equivalence to construct a ldquovirtual correlation matrixrdquo with a higher dimension than the number of receiving elements. This allows for more sources to be resolved than with traditional MUSIC, where the number of...
In this paper, we propose a new approach for compressed sensing of integer-valued signals using prime numbers. In particular, we utilize the logarithmic values of prime numbers to construct projection matrices that are capable of significant reductions in the number of observations (m) needed for the recovery of integer-valued signals when compared to leading compressed-sensing methods. At one extreme,...
In this paper an efficient decoding algorithm is proposed for concatenated coding schemes that use a Reed-Solomon (RS) code as the outer code and a convolutional code as the inner code. We compare the proposed decoding algorithm with Pyndiah's algorithm in terms of both computational complexity and performance. The proposed decoding algorithm reduces the decoding complexity by adopting Kaneko's decoding...
In ultra wide band (UWB) positioning systems, the key problem is to detect the timing of transmitted UWB pulses. Narrow pulses are required for high precision of positioning, thus demanding high sampling rate. To alleviate the difficulty for analog-to-digital converters (ADC) and utilize the feature of time sparsity of UWB pulses, a compressed sensing based scheme is proposed, in which the received...
Compressive sensing is a revolutionary idea proposed recently to achieve much lower sampling rate for sparse signals. For large wireless sensor networks, the events are relatively sparse compared with the number of sources. Because of deployment cost, the number of sensors is limited, and due to energy constraint, not all the sensors are turned on all the time. In this paper, the first contribution...
A cognitive Multiple Access Channel with a Wire-tapper (cMAC-WT) is studied, where one of the two encoders is cognitive, in the sense that it knows a priori the message of the other encoder. Both the discrete and Gaussian models are considered. General achievable rates and outer bounds to the secrecy capacity region are derived, and the secrecy capacity region is identified for the special cases of...
In this paper, we consider the problem of placing, with course-grained control, a large number of wireless networked sensor nodes employing a clustering network architecture. The goal of the deployment strategy is to maximize the lifetime while ensuring connectivity between cluster-heads so that samples from the monitored area may be forwarded to a fusion center. A model is derived to approximate...
Transcribed exons in genes are joined together at donor and acceptor splice sites precisely and efficiently to generate mRNAs capable of being translated into proteins. The sequence variability in individual splice sites can be modeled using Shannon information theory. In the laboratory, the degree of individual splice site use is inferred from the structures of mRNAs and their relative abundance...
We consider in this paper a single-channel wireless sensor network (WSN) where communication among sensor nodes are subject to jamming by an attacker. In particular, we address the detection of a jamming event, and investigate the optimal network defense strategy to mitigate jamming effects. A multiple-monitor distributed detection structure is considered. The optimal detection scheme is developed...
In this paper, energy efficient estimation of an unknown parameter in Gaussian noise is studied in a sensor networking context. A new approach is suggested to obtain a good approximation to the traditional maximum likelihood (ML) estimate, which can save energy by reducing the number of sensor transmissions. Specifically, we describe a new and simple transmission scheme in which the sensor transmissions...
In this paper, we have considered the optimization of the M-ary quadrature amplitude modulation (MQAM) constellation size to minimize the bit energy consumption under average bit error rate (BER) constraints. In the computation of the energy expenditure, the circuit, transmission, and retransmission energies are taken into account. A combined log-normal shadowing and Rayleigh fading model is employed...
In emitter geo-location estimation systems, it is well known that the geometry between sensors and the emitter can seriously impact the accuracy of the location estimate. Here we consider a case where a set of sensors is tasked to perform a sequence of location estimates on an emitter as the sensors progress throughout their trajectories. The goal is to select the trajectories so as to optimally improve...
Improvements in emerging practical network coding methods, such as multi-generation Mixing (MGM), can be attributed to two arguably independent factors: (1) An intrinsic factor that is due to the cooperation among intermediate (propagating) nodes in mixing traffic received through multiple routing paths. (2) An extrinsic factor that is due to the level of reliability provided by network coding from...
Finding sparse solutions of under-determined systems of linear equations is a problem of significance importance in signal processing and statistics. In this paper we study an iterative reweighted least squares (IRLS) approach to find sparse solutions of underdetermined system of equations based on smooth approximation of the L0 norm and the method is extended to find sparse solutions from noisy measurements...
Previous work on sparse approximations has shown that in the pursuit of a signal model using greedy iterative algorithms, the efficiency of the representation can be increased by considering the interference between selected atoms. However, in such interference-adaptive algorithms, atoms are still often selected that necessitate correction by subsequently chosen atoms. It is thus logical to remove...
We present a unified linear program formulation for optimal content delivery in content delivery networks (CDNs), taking into account various costs and constraints associated with content dissemination from the origin server to storage nodes, data storage, and the eventual fetching of content from storage nodes by end users. Our formulation can be used to achieve a variety of performance goals and...
In cellular wideband code-division multiple-access (WCDMA) systems, several transmitted data sequences can be separated because of the unique spreading codes which are designed to be orthogonal. However, cochannel interference and multipath propagation usually destroy this orthogonality at the receiver. We present a composite cyclodespreader that compensates for this distortion by exploiting the cyclostationary...
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