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{"id":28714,"date":"2012-11-05T13:21:00","date_gmt":"2012-11-05T04:21:00","guid":{"rendered":"https:\/\/heungno.net\/?p=28714"},"modified":"2024-01-02T14:44:46","modified_gmt":"2024-01-02T05:44:46","slug":"information-and-system-group","status":"publish","type":"post","link":"https:\/\/heungno.net\/?p=28714","title":{"rendered":"Information and System Group"},"content":{"rendered":"
Information and System Group seminar materials<\/p>\n\n\n
November 2015<\/p>\n\n\n\n
1<\/td>
<\/td>
2015-11-27<\/td>
Support recovery with orthogonal matching pursuit in the presence of noise<\/td>
In this paper, sufficient and necessary conditions for correct recovery of sparse solution using OMP under the noisy environment are provided. In addition, upper bound of the error rate in recovering is studied. The results are characterized by restricted isometry constant and signal-to-noise ratio.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n\n\n\n
July 2015<\/p>\n\n\n\n
1<\/td>
<\/td>
2015-07-20<\/td>
An experimental performance evaluation of a novel radio-transmitter identification system under diverse environmental conditions<\/td>
In this paper, the effects of environmental conditions on a radio-transmitter identification system are investigated<\/strong><\/strong>. C<\/u><\/em>hanging in environmental conditions causes the feature vectors to spread over the feature space,<\/u><\/em> resulting in classification performance degradation. This performance degradation can be compensated for by training the system with data collected in a range of battery-voltage and ambient temperature levels.<\/u><\/em> The SNR vs Classification accuracy is also determined for systems operating in noisy channels. The transient features are extracted using a technique based on the amplitudes and phase changes of the received signals<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
June 2015<\/p>\n\n\n\n
1<\/td>
<\/td>
2015-06-29<\/td>
Coexistence Decision Making for Spectrum Sharing among Heterogeneous Wireless Systems<\/td>
In this paper authors tackle spectrum sharing with an objective of enabling coexistence among dissimilar TVWS networks. The sharing problem is defined as multi-objective optimization problem (MOOP). An algorithm to solve the MOOP has also been presented in the paper. Finally the simulation study shows the superiority of the proposed algorithm over existing coexistence decision making algorithms in terms of fairness and percentage of demand served.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
April 2015<\/p>\n\n\n\n
1<\/td>
<\/td>
2015-04-13<\/td>
Fast Non-Negative Orthogonal Matching Pursuit<\/td>
Non-negative signal is an important class of sparse signals. Many algorithms have already been proposed to recover such non-negative sparse representations. One of such modification is Non-Negative Orthogonal Matching Pursuit(NNOMP), which satisfies non-negative constraint by selecting positive coefficients and using a non-negative optimization technique. However, since it consumes the extra computational costs, the most significant benefit of OMP\u2014fast implementation\u2014cannot be exhibited. Therefore, author proposed a fast implementation of NNOMP similar with canonical fast OMP based on QR decomposition method, called Fast Non-Negative Orthogonal Matching Pursuit(FNNOMP).<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
2<\/td>
<\/td>
2015-04-27<\/td>
Opportunistic Routing Algorithm for Relay Node Selection in Wireless Sensor Networks<\/td>
Energy saving optimization has become one of the major concerns in wireless sensor network (WSN) routing protocol design, due to the fact that most sensor nodes are equipped with limited non-rechargeable battery power. This paper focuses on minimizing energy consumption and maximizing network lifetime for data relay in one-dimensional (1-D) queue network. Using opportunistic routing theory, multihop relay decision to optimize the network energy efficiency is made based on the differences among sensor nodes, in terms of both their distance to sink and the residual energy of each other. Specifically, an Energy Saving via Opportunistic Routing (ENS_OR) algorithm is designed to ensure minimum power cost during data relay and protect the nodes with relatively low residual energy. Extensive simulations and real testbed results show that the proposed solution ENS_OR can significantly improve the network performance on energy saving and wireless connectivity in comparison with other existing WSN routing schemes.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
\nMarch 2015<\/p>\n\n\n\n\n\n\n\n
1<\/td>
<\/td>
2015-03-23<\/td>
Cooperative Spectrum Access Towards Secure \nInformation Transfer for CRNs<\/td>
Asif<\/td>
<\/td>
<\/td><\/tr>
<\/td>
<\/td>
<\/td>
Encryption at upper layers becomes challenging for a network without infrastructure. Moreover, the encryption algorithms could be compromised. An alternative way for enhancing the security is to use physical layer security, or information-theoretic security by protecting the transmitted signal from being received or decoded by the eavesdroppers. In this paper authors make use of it to introduce a cooperative spectrum access for secure information transfer in CRNs. They show that security of the PU\u2019s information is enhanced using SUs meanwhile SUs in reward get fair opportunity to access channel for their own information transfer.<\/td><\/tr>
2<\/td>
<\/td>
2015-03-30<\/td>
Specific emitter identification based on Hilbert-Huang transform-based time-frequency-energy distribution features<\/td>
Jusung Kang<\/td>
<\/td>
<\/td><\/tr>
<\/td>
<\/td>
<\/td>
In this paper, a novel specific emitter identification method is proposed. The time-frequency-energy distribution of transient signal is obtained by Hilbert-Huang transform (HHT). The phase based method and self-adaptive threshold based on the HHT is used to extract the transient signal. After that, PCA and SVM is used for classification. 8 mobile phones are used to evaluate the performance of this proposed method.The result said that this proposed method is more useful than other RF fingerprint method based on amplitude, phase, frequency, and energy envelop. Also they said that this method could be applicable for any security issues of wireless network.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
\nJanuary 2015<\/p>\n\n\n\n\n\n\n\n
1<\/td>
<\/td>
2015-01-12<\/td>
Sparsity-Aware Sphere Decoding: Algorithms and Complexity Analysis<\/td>
Hwanchol Jang<\/td>
(doc)<\/td>
<\/td><\/tr>
<\/td>
<\/td>
<\/td>
Integer least-squares problems, concerned with solving a system of equations where the components of the unknown vector are integer-valued, arise in a wide range of applications. In many scenarios the unknown vector is sparse, i.e., a large fraction of its entries are zero. Examples include applications in wireless communications, digital fingerprinting, and array-comparative genomic hybridization systems. Sphere decoding, commonly used for solving integer least-squares problems, can utilize the knowledge about sparsity of the unknown vector to perform computationally efficient search for the solution. In this paper, we formulate and analyze the sparsity-aware sphere decoding algorithm that imposes L0-norm constraint on the admissible solution. Analytical expressions for the expected complexity of the algorithm for alphabets typical of sparse channel estimation and source allocation applications are derived and validated through extensive simulations. The results demonstrate superior performance and speed of sparsity-aware sphere decoder compared to the conventional sparsity-unaware sphere decoding algorithm. Moreover, variance of the complexity of the sparsity-aware sphere decoding algorithm for binary alphabets is derived. The search space of the proposed algorithm can be further reduced by imposing lower bounds on the value of the objective function. The algorithm is modified to allow for such a lower bounding technique and simulations illustrating efficacy of the method are presented. Performance of the algorithm is demonstrated in an application to sparse channel estimation, where it is shown that sparsity-aware sphere decoder performs close to theoretical lower limits.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n\n\n\n
December 2014<\/p>\n\n\n\n
1<\/td>
2014-12-08<\/td>
K-SVD: An Algorithm for Designing Overcomplete Dictionaries for Sparse Representation<\/td>
<\/td>
Haeung<\/td>
<\/td>
<\/td><\/tr>
<\/td>
<\/td>
Using an overcomplete dictionary that contains prototype of signal-atoms, signals are described by sparse linear combinations of these atoms. In this paper, authors introduce a novel algorithm for adapting dictionaries in order to achieve sparse representations\u2014the k-SVD algorithm. This algorithm repeats sparse coding with current dictionary and updating the dictionary to better fit the data. And the authors analyze this algorithm and demonstrate its results.<\/td>
<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
2<\/td>
2014-12-22<\/td>
Fronthaul Compression for Cloud Radio Access Networks<\/td>
We discuss from this paper how to derive the theoretical probability of recovery for the orthogonal matching pursuit (OMP) algorithm. It is known that, till date, there is no theoretical phase transition analysis present for the OMP algorithms. The analysis presented in this paper could be used as a starting point to derive the phase transitions for the OMP algorithm. We discuss a key theorem and its proof in this talk.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n\n\n\n
September 2014<\/p>\n\n\n\n
1<\/td>
<\/td>
2014-09-22<\/td>
Distributed Channel Coding for Underwater Acoustic \nCooperative Networks<\/td>
This paper introduces a way to evaluate an N-dimensional integration whose integrand is a determinant of a matrix. This approach in this paper is general in nature and in particular, it is useful to derive eigenvalue distributions of Wishart matrices.<\/span><\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n
3<\/td>
<\/td>
2014-04-01<\/td>
Identifying Wireless User via Transmitter Imperfections<\/td>
This letter derives sufficient conditions for the OMP to recover the support set of a sparse vector from noise corrupted measurements. In particular, the conditions are given in terms of the minimum absolute values of the signal amplitudes. That is, if the minimum values of the non-zero coefficient of the signal satisfies certain conditions then OMP guarantees exact support recovery.<\/td><\/tr>
They present an approach to designing capacity approaching high-girth low-density parity-check (LDPC) codes that are friendly to hardware implementation, and compatible with some desired input code structure defined using a protograph. The approach is based on a mapping of any class of codes defined using a protograph into a family of hierarchical quasi- cyclic (HQC) LDPC codes. Next, they present a girth-maximizing algorithm that optimizes the degrees of freedom within the family of codes to yield a high-girth HQC LDPC code, subject to bounds imposed by the fact that HQC codes are still quasi-cyclic. Finally, they discuss how certain characteristics of a code protograph will lead to inevitable short cycles and show that these short cycles can be eliminated using a \u201csquashing\u201d procedure that results in a high-girth QC LDPC code.<\/td><\/tr>
In this paper, they have introduced two novel ultra-wideband (UWB) channel estimation approaches based on compressive sensing (CS). The proposed approach relies on the fact that transmitting an ultra-short pulse through a multipath UWB channel leads to a received UWB signal that can be approximated by a linear combination of a few atoms from a pre-defined dictionary which means sparse representation of the received signal. The key in the proposed approach is in the design of a dictionary of parameterized waveforms (atoms) that closely matches the information-carrying pulse shape leading thus to higher energy compaction and sparse representation, and, therefore higher probability for CS reconstruction. In the first approach, the CS reconstruction capabilities are exploited to recover the composite pulse-multipath channel from a reduced set of random projections. This reconstructed signal is subsequently used as a referent template in a correlator-based detector. In the second approach, from a set of random projections of the received pilot signal, the Matching Pursuit algorithm is used to identify the strongest atoms in the projected signal that are related to the strongest propagation paths that composite the multipath UWB channel.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
August 2013<\/strong><\/p>\n\n\n\n\n\n\n\n
No<\/td>
Date<\/td>
Title<\/td>
Speaker<\/td>
Presentation<\/td>
Discussion<\/td><\/tr>
1<\/td>
2013-08-01<\/td>
Compressive Sensing for Spread Spectrum Receivers<\/td>
This paper investigates the use of Compressive Sensing(CS) in a general Code Division Multiple Access (CDMA) receiver. They show that when using spread spectrum codes in the signal domain, the CS measurement matrix may be simplified. Furthermore, they numerically evaluate the proposed receiver in terms of bit error rate under different signal to noise ratio conditions and compare it with other receiver structures.<\/td><\/tr>
2<\/td>
2013-08-08<\/td>
Active illumination single-pixel camera based on compressive sensing<\/td>
This paper is organized as follows. After a brief introduction (Section 1), some mathematical back- ground essential to the understanding of CS is shown (Section 2). Then, in Section 3, CS is presented along with some of its principal properties. Section 4 explains why the \u21131-norm is such a good option for com- pressive sensing. Some insights about the robustness of CS in the presence of noise are given in Section 5. Next, in Section 6, the single-pixel camera developed at Rice University is discussed. Subsequently, the innovative active illumination single-pixel camera developed in the scope of the current work is described. Following that, experimental results from the single-pixel cameras are presented. In the end, the main conclusions of this work are exposed.<\/div>\n<\/td><\/tr>
3<\/td>
2013-08-29<\/td>
Resource Allocation in Cognitive Radio Relay Networks<\/td>
In this paper authors formulate the problem of Resource Allocation (RA) in Cognitive Radio (CR) networks with relay stations. The problem takes into account the issues like: fluctuations of usable spectrum resource, channel quality variations caused by frequency selectivity, and interference caused by different transmit power levels. They propose easy to implement heuristic algorithms. The simulation results reveal that presented solutions show good proportional fairness among CR users and improvement in system throughput by power control.<\/td><\/tr>
In this paper, they propose an algorithm referred to as multipath matching pursuit that investigates multiple promising candidates to recover sparse signals from compressed measurements. Their method is inspired by the fact that the problem to find the candidate that minimizes the residual is readily modeled as a combinatoric tree search problem and the greedy search strategy is a good fit for solving this problem. In the empirical results as well as the restricted isometry property (RIP) based performance guarantee, they show that the proposed MMP algorithm is effective in reconstructing original sparse signals for both noiseless and noisy scenarios.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
July 2013<\/strong><\/p>\n\n\n\n\n\n\n\n
No<\/td>
Date<\/td>
Title<\/td>
Speaker<\/td>
Presentation<\/td>
Discussion<\/td><\/tr>
1<\/td>
2013-07-11<\/td>
A sparse signal reconstruction perspective for source localization with sensor arrays<\/td>
In this paper, the authors present a source localization method based on sparse representation of sensor measurements. In particular, they use SVD of the data matrix obtained from the sensors to summarize the multiple measurements. The SVD summarized data is then sparsely represented in order to detect the sources. The authors also proposed grid refinement in order to mitigate the effects of limiting estimates to a grid of spatial locations. They demonstrate the superior resolution ability with limited time samples of their method over the existing methods via various experiments.<\/td><\/tr>
2<\/td>
2013-07-18<\/td>
Enhancing Iterative Decoding of Cyclic LDPC Codes Using Their Automorphism Groups<\/td>
In this paper they focus on cyclic LDPC codes defined by a circulant parity-check matrix and consider two known subgroups of the automorphism group of a cyclic code. For the large class of idempotent-based cyclic LDPC codes in the literature, they show that the two subgroups only provide equivalent parity-check matrices and thus cannot be harnessed for iterative decoding. Towards exploiting the automorphism group of a code, they propose a new class of cyclic LDPC codes based on pseudo-cyclic MDS codes with two information symbols,for which nonequivalent parity-check matrices are obtained. Simulation results show that for our constructed codes of short lengths, the automorphism group can significantly enhance the iterative decoding performance.<\/td><\/tr>
Abstract: This paper has discussed about design and analysis of multiuser \ndetection (MUD) using sparsely spread CDMA systems. The objective of \nthe MUD problem is how to detect multiple user signals \nsimultaneously at the low computational cost. The main obstacle is \nmultiple-access interference (MAI). These multiple user signals are \ninterference for each user detection one another. The MAI problem \narise in most CDMA systems, and optimal detection in such systems \nrequires exponentially growing computation as the number of user \nincreases. But a good news is that the simultaneous users in time is \nvery few. Therefore, this paper investigates a suboptimal MUD \ndetection using sparse CDMA systems. The key idea of the proposed \nsystem is to encode the transmitted waveforms using sparse spread \nCDMA codes and detect the signal using a linear-complexity belief \npropagation (BP) algorithm. We summarize the contributions of this \nwork is following: \n– Description the sparse CDMA system \n– Properties of the sparsly spread CDMA codes for the convergence of the BP algorithm \n– Design of the BP algorithm for the MUD problem \n– Asymptotic analysis of performance of the BP algorithm based MUD detection \nIn this report, we aim to sketch the key point of each contribution \nof this paper.<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n
June 2013<\/strong><\/p>\n\n\n\n\n\n\n\n
No<\/td>
Date<\/td>
Title<\/td>
Speaker<\/td>
Presentation<\/td>
Discussion<\/td><\/tr>
1<\/td>
2013-06-13<\/td>
Signal Recovery From Random Measurements Via Orthogonal Matching Pursuit<\/td>