ppxscal/embedding_network huggingface dataset:
Time--frequency and time--time filtering with the S-transform and TT-transform
Authors: C. R. Pinnegar
Venue: Digital Signal Processing (2005)

The limitations of frequency-domain filtering methods have motivated the development of alternative techniques, in which a filter is applied to a time-frequency distribution instead of the Fourier spectrum. One such distribution is the S-transform, a modified short-time Fourier transform whose window scales with frequency, as in wavelets. Recently it has been shown that the S-transform's local spectra have time-domain equivalents. Since each of these is associated with a particular window position on the time axis, collectively they give a time-time distribution. This distribution, called the TT-transform, exhibits differential concentration of different frequency components, with higher frequencies being more strongly concentrated around the localization position than lower frequencies. This leads to the idea of filtering on the time-time plane, in addition to the time-frequency plane. Examples of time-frequency filtering and time-time filtering are presented.
Meeting the challenges of knowledge management at the Housing and Development Board
Authors: Thompson S. H. Teo
Venue: Decision Support Systems (2005)

In recent years, there has been increased emphasis on the importance of knowledge management (KM) in facilitating knowledge sharing, enhancing productivity, and increasing business competitiveness. This paper examines the development of a knowledge portal (called KnowIT) at the Housing and Development Board in Singapore. The issues and insights gained from HDB's experience are examined. These issues and insights serve as important lessons to firms intending to embark on a KM project.
Identification of cellular dynamic patterns resulting from repetitive photobleaching using independent component analysis
Authors: A. M. C. Van Gemert, C. R. Jost, A. M. A. Van Der Laan, R. W. Dirks, J. H. C. Reiber, H. J. Tanke, B. P. F. Lelieveldt
Venue: Proceedings of the Sixth IEEE international conference on Symposium on Biomedical Imaging: From Nano to Macro (2009)

Fluorescence Loss In Photobleaching (FLIP) experiments are used to determine the dynamic properties of fluorescently labeled macromolecules in cells. This paper presents a novel method to facilitate the interpretation of dynamic patterns in FLIP experiments based on Independent Component Analysis. By decomposing the image sequence into a stationary and a dynamic component, and by deriving a bleaching contrast function, we demonstrate that the triplet of component and bleaching images enhances the interpretation of FLIP sequences by outlining the movement of two fluorescent proteins with well defined dynamic characteristics.
Modified Euclidean algorithms for decoding Reed-Solomon codes
Authors: Dilip V. Sarwate, Zhiyuan Yan
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 2 (2009)

The extended Euclidean algorithm (EEA) for polynomial greatest common divisors is commonly used in solving the key equation in the decoding of Reed-Solomon (RS) codes, and more generally in BCH decoding. For this particular application, the iterations in the EEA are stopped when the degree of the remainder polynomial falls below a threshold. While determining the degree of a polynomial is a simple task for human beings, hardware implementation of this stopping rule is more complicated. This paper describes a modified version of the EEA that is specifically adapted to the RS decoding problem. This modified algorithm requires no degree computation or comparison to a threshold, and it uses a fixed number of iterations. Another advantage of this modified version is in its application to the errors-and-erasures decoding problem for RS codes where significant hardware savings can be achieved via seamless computation.
Energy-aware data gathering in wireless sensor networks
Authors: Soyoung Hwang, Gwang-Ja Jin, Changsub Shin, Bongsoo Kim
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

Many routing protocols have been proposed for sensor networks where energy awareness and reliability are essential design issues. This paper proposes an energy-aware data gathering method called Energy-aware Tree Routing (ETR) in Wireless Sensor Networks. The proposed scheme relates to reliable and energy efficient data routing by selecting a data transmission path in consideration of residual energy at each node to disperse energy consumption across the networks and reliably transmit the data through a detour path when there is link or node failure. Simulation results show that the proposed method outperformed traditional Tree Routing (TR) by 23%∼55% in network lifetime.
Diversity-multiplexing tradeoff-optimal code constructions for symmetric MIMO multiple access channels
Authors: Hsiao-Feng Lu, Camilla Hollanti
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

An explicit, systematic code construction for the symmetric MIMO (multi-input multi-output) multiple access (MAC) channel with any number of users and any numbers of transmit and receive antennas is presented in this paper. The users are assumed to transmit at the same level of multiplexing gain. This newly constructed code is proved to achieve the optimal MIMO-MAC diversity-multiplexing tradeoff.
A MAC protocol for multi-packet ad-hoc wireless network utilizing multi-antenna
Authors: Norihiko Sato, Takeo Fujii
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

In this paper, we propose a novel multi-antenna utilization scheme for avoiding the packet congestion around the gateway (GW) of the ad-hoc wireless networks. In our previous work, we have discussed the number of antenna design for suitable for packet congestion around the GW. However, only multi-user access with multi-antenna is considered at the receiver node. Moreover, we do not consider the effective media access control (MAC) protocol for this kind of networks. In this paper, in order to realize the effective multi-packet access ad-hoc wireless networks, we consider applying multi-input multi-output (MIMO) technique for packet transmission to the next hop node, and we also propose a MAC protocol avoiding the hidden node problem for supporting the multi-packet access with multi-antenna at the nodes around the GW.
Efficient architectures for modulo 2n-1 squarers
Authors: A. Spyrou, D. Bakalis, H. T. Vergos
Venue: Proceedings of the 16th international conference on Digital Signal Processing (2009)

Two novel architectures for designing modulo 2n-1 squarers are given. The first one does not perform any encoding on the input operand, while the second one uses Booth-encoding. Pre-layout estimates indicate that both architectures result in area and/or delay efficient modulo 2n-1 squarers. The non-encoded modulo squarers are more suitable for small values of n while the Booth-encoded modulo squarers are more suitable for medium and large values of n.
Using Kolmogorov complexity for understanding some limitations on steganography
Authors: Boris Ryabko, Daniil Ryabko
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 4 (2009)

Perfectly secure steganographic systems have been recently described for a wide class of sources of covertexts. The speed of transmission of secret information for these stegosystems is proportional to the length of the covertext. In this work we show that there are sources of covertexts for which such stegosystems do not exist. The key observation is that if the set of possible covertexts has a maximal Kolmogorov complexity, then a high-speed perfect stegosystem has to have complexity of the same order.
Sequential probability assignment via online convex programming using exponential families
Authors: Maxim Raginsky, Roummel F. Marcia, Jorge Silva, Rebecca M. Willett
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 2 (2009)

This paper considers the problem of sequential assignment of probabilities (likelihoods) to elements of an individual sequence using an exponential family of probability distributions. We draw upon recent work on online convex programming to devise an algorithm that does not require computing posterior distributions given all current observations, involves simple primal-dual parameter updates, and achieves minimax per-round regret against slowly varying product distributions with marginals drawn from the same exponential family. We validate the theory on synthetic data drawn from a time-varying distribution over binary vectors of high dimensionality.
Tennissense: a platform for extracting semantic information from multi-camera tennis data
Authors: Ciarán Ó Conaire, Philip Kelly, Damien Connaghan, Noel E. O'Connor
Venue: Proceedings of the 16th international conference on Digital Signal Processing (2009)

In this paper, we introduce TennisSense, a technology platform for the digital capture, analysis and retrieval of tennis training and matches. Our algorithms for extracting useful metadata from the overhead court camera are described and evaluated. We track the tennis ball using motion images for ball candidate detection and then link ball candidates into locally linear tracks. From these tracks we can infer when serves and rallies take place. Using background subtraction and hysteresis-type blob tracking, we track the tennis players positions. The performance of both modules is evaluated using ground-truthed data. The extracted metadata provides valuable information for indexing and efficient browsing of hours of multi-camera tennis footage and we briefly illustrative how this data is used by our tennis-coach playback interface.
On the convergence of iterative belief propagation
Authors: Axel Heim, Ulrich Sorger
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

The convergence of iterative decoding schemes utilizing belief propagation is considered. A quantitative bound for the output L-values of a Turbo decoder is given that only depends on the received word and thus is independent from the decoder iterations. Further, it is shown that the exponential increase of the L-values in each iteration within an LDPC decoder is limited by the degree of the variable nodes.
A unified framework for designing FIR filters with arbitrary magnitude and phase response
Authors: Shefeng Yan, Yuanliang Ma
Venue: Digital Signal Processing (2004)

A unified framework for the optimal design of finite impulse response (FIR) filters with arbitrary magnitude and phase response using second-order cone (SOC) programming is proposed. FIR filters with desired frequency response can be implemented by minimizing the frequency domain response error measure (L"1, L"2, or L"~ norm of the error) between the desired response and the designed filter response. Some constraints can also be imposed in the passband or/and stopband to satisfy applications-oriented requirements. These optimal design problems can be reformulated as convex optimization form as the second-order cone programming and solved efficiently via the well-established interior point method. The SOC programming approach allows much more design flexibility in comparison to the classical minimax, least-square, and eigenfilter approaches. Computer simulations are presented to illustrate the developed algorithms and to evaluate the design performance. Simulation results for the design of fractional delay FIR filters and filters with desired frequency response show good performance of the proposed methods.
A GLRT for multichannel radar detection in the presence of both compound Gaussian clutter and additive white Gaussian noise
Authors: Bin Liu, Biao Chen, James H. Michels
Venue: Digital Signal Processing (2005)

Motivated by multichannel radar detection applications in the presence of both white Gaussian noise and Gaussian clutter with unknown power, we develop maximum likelihood parameter estimates for the disturbance process. Both cases with known and unknown white noise variance are treated. As the estimators do not admit closed-form solutions, numerical iterative procedures are developed that are guaranteed to at least converge to the local maximum. The developed estimates allow us to construct a generalized likelihood ratio test (GLRT) for the detection of a signal with constant but unknown amplitude. This GLRT has important applications in multichannel radar detection involving both white Gaussian noise and spherically invariant random process clutter and is shown to have better detection performance and CFAR property compared with existing statistics.
Approximate capacity of a class of Gaussian relay-interference networks
Authors: Soheil Mohajer, Suhas N. Diggavi, David N. C. Tse
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 1 (2009)

In this paper we study the Gaussian relay-interference network, in which relay (helper) nodes are to facilitate competing information flows over a wireless network. We examine this problem for certain regimes of channel values, when one of the cross-links is dominated by noise, resulting in Z and/or S configurations for the networks. For these Gaussian ZZ and ZS networks, we establish an approximate characterization of the rate region. The outer bounds to the capacity regions are established using genie-aided techniques that extend the methods used for the Gaussian interference channel to the relay-interference network. For the inner bound of the ZZ network, we utilize a new interference management scheme, termed interference neutralization, which was inspired by our earlier study of such deterministic networks. This technique allows for over-the-air interference removal, without the transmitters having complete access to the interfering signals.
Low-complexity near-ML decoding of large non-orthogonal STBCs using reactive tabu search
Authors: N. Srinidhi, Saif K. Mohammed, A. Chockalingam, B. Sundar Rajan
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

Non-orthogonal space-time block codes (STBC) with large dimensions are attractive because they can simultaneously achieve both high spectral efficiencies (same spectral efficiency as in V-BLAST for a given number of transmit antennas) as well as full transmit diversity. Decoding of non-orthogonal STBCs with large dimensions has been a challenge. In this paper, we present a reactive tabu search (RTS) based algorithm for decoding non-orthogonal STBCs from cyclic division algebras (CDA) having large dimensions. Under i.i.d fading and perfect channel state information at the receiver (CSIR), our simulation results show that RTS based decoding of 12 × 12 STBC from CDA and 4-QAM with 288 real dimensions achieves i) 10-3 uncoded BER at an SNR of just 0.5 dB away from SISO AWGN performance, and ii) a coded BER performance close to within about 5 dB of the theoretical MIMO capacity, using rate-3/4 turbo code at a spectral efficiency of 18 bps/Hz. RTS is shown to achieve near SISO AWGN performance with less number of dimensions than with LAS algorithm (which we reported recently) at some extra complexity than LAS. We also report good BER performance of RTS when i.i.d fading and perfect CSIR assum ptions are relaxed by considering a spatially correlated MIMO channel model, and by using a training based iterative RTS decoding/channel estimation scheme.
Fourier analysis of symbolic data: A brief review
Authors: Vera Afreixo, Paulo J. S. G. Ferreira, Dorabella Santos
Venue: Digital Signal Processing (2004)

We overview and discuss several methods for the Fourier analysis of symbolic data, such as DNA sequences, emphasizing their mutual connections. We consider the indicator sequence approach, the vector and the symbolic autocorrelation methods, and methods such as the spectral envelope, that for each frequency optimize the symbolic-no-numeric mapping to emphasize any periodic data features. We discuss the equivalence or connections between these methods. We show that it is possible to define the autocorrelation function of symbolic data, assuming only that we can compare any two symbols and decide if they are equal or distinct. The autocorrelation is a numeric sequence, and its Fourier transform can also be obtained by summing the squares of the Fourier transform of indicator sequences (zero/one sequences indicating the position of the symbols). Another interpretation of the spectrum is given, borrowing from the spectral envelope concept: among all symbolic-to-numeric mappings there is one that maximizes the spectral energy at each frequency, and leads to the spectrum.
SeGCom: secure group communication in VANETs
Authors: Mayank Verma, Dijiang Huang
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

In this paper, we propose a novel scheme to achieve secure, and efficient vehicular communication. In particular, SegCom provides two mechanisms to perform successive authentication of the vehicle with the road-side infrastructure units to expedite authentication for Vehicle-to-Infrastructure (V2I) communication. Furthermore, to enhance the efficiency of Vehicle-to-Vehicle (V2V) communication, SeGCom permits the vehicles to form group, which are also used for performing multi-hop V2V communication without any assistance from a trusted authority. Comparison with other existing schemes in the literature has been performed to show the efficiency and applicability of our scheme.
Adaptive blind multiuser equalizer based on pdf matching
Authors: Adel Daas, Mahmoud Hadef, Stephan Weiss
Venue: Proceedings of the 16th international conference on Telecommunications (2009)

In this paper, we propose a new adaptive technique for blind multiuser equalisation. The proposed approach is based on fitting the probability density function (pdf) of the equalizer output to the desired pdf of the corresponding symbol alphabet. The underlying pdf at the equalizer output is estimated by means of the Parzen Window method. A switch between blind and Decision Directed adaptation is possible by manipulating the kernal size of the Parzen Window Estimator. The cost function of the proposed technique can be measured by a stochastic gradient descent approach. The performance of the proposed adaptation strategy is assessed by a number of simulations, and benchmarked against Firmer-CMA under QPSK modulation.
Efficient RFID anti-collision scheme with multi-collision reflected frame request
Authors: Sangho Seo, Sin-Chong Park
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

To reduce the searching time of the whole transponders in the interrogator's operation range, this paper uses a tree-based searching scheme with multi-collision reflected frame request and multi-responding tag scheduling scheme. This scheme enables efficient burst UID receptions of the transponders, and eliminates unnecessary frame overhead. To show the feasibility of this scheme, total searching time is simulated as a parameter of UID length and tag density. The results are compared with that of the basic tree-based anti-collision scheme, and the better performance is reported. Especially for the same UID length, the proposed scheme can reduces the searching time up to 50%.
Interference alignment with limited feedback
Authors: Jatin Thukral, Helmut Bölcskei
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 3 (2009)

We consider single-antenna interference networks where M sources, each with an average transmit power of P/M, communicate with M destinations over frequency-selective channels (with L taps each) and each destination has perfect knowledge of its channels from each of the sources. Assuming that there exist error-free non-interfering broadcast feedback links from each destination to all the nodes (i.e., sources and destinations) in the network, we show that naive interference alignment, in conjunction with vector quantization of the impulse response coefficients according to the scheme proposed in Mukkavilli et al., IEEE Trans. IT, 2003, achieves full spatial multiplexing gain of M/2, provided that the number of feedback bits broadcast by each destination is at least M(L - 1) log P.
An adaptive coherence filter
Authors: Jeremy R. Waller, Gary D. Brushe
Venue: Digital Signal Processing (2005)

This paper derives an adaptive coherence filter for canceling interference from a signal of interest whose power spectral density is symmetric. A basic property of the Fourier transform of real signals is that their spectra are Hermitian symmetric. This property is exploited to determine which part of a spectrum is interference and which part is the signal of interest. An unconstrained Wiener filter is derived that exploits the frequency domain symmetry of the signal of interest. While the adaptive coherence filter is based on the Fourier transform property of real signals, an extension of the algorithm is provided so the filter can be used on any signal that displays spectral symmetry. A practical method for implementing the filter is provided. The filter has application in the area of telecommunications, but is applicable in wireless communication applications where a signal, that displays spectral symmetry, is corrupted by interfering signals within the signal of interest's bandwidth.
A group-level incentive scheme for data collection in wireless sensor networks
Authors: Long Cheng, Canfeng Chen, Jian Ma, Yimin Chen
Venue: Proceedings of the 6th IEEE Conference on Consumer Communications and Networking Conference (2009)

Utilizing mobile devices such as PDAs, cell phones to collect and deliver sensor data is considered as a promising application in future ubiquitous computing environment. In such application scenarios, the human factor is becoming increasingly important. In this paper, we propose a group-level incentive scheme targeted for encouraging mobile users to collect sensor data. Such idea of widening the scope of incentive from device-level to group-level is inspired by the incentive scheme of blood donation in real life. Mobile users earn credits by collecting and delivering sensor data with their mobile devices and they may consume the credits to access the services provided by wireless sensor networks applications. The main idea of the group-level incentive scheme is to group mobile users into social groups and share credits so that credits earned by one user can be consumed by another user in the same group. Through theoretical analysis and simulation we illustrate the potential of the proposed solution.
Bit precision analysis for compressed sensing
Authors: Ehsan Ardestanizadeh, Mahdi Cheraghchi, Amin Shokrollahi
Venue: Proceedings of the 2009 IEEE international conference on Symposium on Information Theory - Volume 1 (2009)

This paper studies the stability of some reconstruction algorithms for compressed sensing in terms of the bit precision. Considering the fact that practical digital systems deal with discretized signals, we motivate the importance of the total number of accurate bits needed from the measurement outcomes in addition to the number of measurements. It is shown that if one uses a 2k × n Vandermonde matrix with roots on the unit circle as the measurement matrix, O(l+k log n/k) bits of precision per measurement are sufficient to reconstruct a k-sparse signal x ơ Rn with dynamic range (i.e., the absolute ratio between the largest and the smallest nonzero coefficients) at most 2l within l bits of precision, hence identifying its correct support. Finally, we obtain an upper bound on the total number of required bits when the measurement matrix satisfies a restricted isometry property, which is in particular the case for random Fourier and Gaussian matrices. For very sparse signals, the upper bound on the number of required bits for Vandermonde matrices is shown to be better than this general upper bound.