Showing papers by "Alcatel-Lucent published in 2003"
TL;DR: This work provides a simple method to iteratively detect and decode any linear space-time mapping combined with any channel code that can be decoded using so-called "soft" inputs and outputs and shows that excellent performance at very high data rates can be attained with either.
Abstract: Recent advancements in iterative processing of channel codes and the development of turbo codes have allowed the communications industry to achieve near-capacity on a single-antenna Gaussian or fading channel with low complexity. We show how these iterative techniques can also be used to achieve near-capacity on a multiple-antenna system where the receiver knows the channel. Combining iterative processing with multiple-antenna channels is particularly challenging because the channel capacities can be a factor of ten or more higher than their single-antenna counterparts. Using a "list" version of the sphere decoder, we provide a simple method to iteratively detect and decode any linear space-time mapping combined with any channel code that can be decoded using so-called "soft" inputs and outputs. We exemplify our technique by directly transmitting symbols that are coded with a channel code; we show that iterative processing with even this simple scheme can achieve near-capacity. We consider both simple convolutional and powerful turbo channel codes and show that excellent performance at very high data rates can be attained with either. We compare our simulation results with Shannon capacity limits for ergodic multiple-antenna channel.
2,291 citations
TL;DR: This paper discusses how the philosophy and features of OWL can be traced back to these older formalisms, with modifications driven by several other constraints on OWL.
1,630 citations
Patent•
01 Oct 2003
TL;DR: In this article, a technique for detecting and indicating an internal anatomical obstacle encountered during insertion of a medical device into the body of a patient, comprising an elongated member such as a tube, catheter, guidewire, or other device, has been proposed.
Abstract: A technique for detecting and indicating an internal anatomical obstacle encountered during insertion of a medical device into the body of a patient, comprising an elongated member such as a tube, catheter, guidewire, or other device, having a location indicating element, such as a permanent magnet, flexibly coupled to its distal end, and an external detector that tracks and displays the location and orientation of the location indicating element. The flexible coupling has sufficient stiffness to maintain the orientation of the location indicating element against the forces from both gravity and flowing blood within a patient's vasculature, but allows the location indicating element to change orientation if it encounters an obstacle during insertion. The medical caregiver monitors the detector's display and determines encounters with obstacles by observing changes in the orientation of the location indicating element.
610 citations
14 Sep 2003
TL;DR: This paper proposes the Unified Cellular and Ad-Hoc Network (UCAN) architecture for enhancing cell throughput, while maintaining fairness, and refine the 3G base station scheduling algorithm so that the throughput gains of active clients are distributed proportional to their average channel rate.
Abstract: In third-generation (3G) wireless data networks, mobile users experiencing poor channel quality usually have low data-rate connections with the base-station. Providing service to low data-rate users is required for maintaining fairness, but at the cost of reducing the cell's aggregate throughput. In this paper, we propose the Unified Cellular and Ad-Hoc Network (UCAN) architecture for enhancing cell throughput, while maintaining fairness. In UCAN, a mobile client has both 3G cellular link and IEEE 802.11-based peer-to-peer links. The 3G base station forwards packets for destination clients with poor channel quality to proxy clients with better channel quality. The proxy clients then use an ad-hoc network composed of other mobile clients and IEEE 802.11 wireless links to forward the packets to the appropriate destinations, thereby improving cell throughput. We refine the 3G base station scheduling algorithm so that the throughput gains of active clients are distributed proportional to their average channel rate, thereby maintaining fairness. With the UCAN architecture in place, we propose novel greedy and on-demand protocols for proxy discovery and ad-hoc routing that explicitly leverage the existence of the 3G infrastructure to reduce complexity and improve reliability. We further propose a secure crediting mechanism to motivate users to participate in relaying packets for others. Through extensive simulations with HDR and IEEE 802.11b, we show that the UCAN architecture can improve individual user's throughput by up to 310% and the aggregate throughput of the HDR downlink by up to 60%.
509 citations
TL;DR: It is suggested that in addition to regulating the shape, micropatterned frameworks act as sites for stress and impurity release during the amorphous-to-crystalline transition.
Abstract: Micropatterning of single crystals for technological applications is a complex, multistep process. Nature provides alternative fabrication strategies, when crystals with exquisite micro-ornamentation directly develop within preorganized frameworks. We report a bio-inspired approach to growing large micropatterned single crystals. Micropatterned templates organically modified to induce the formation of metastable amorphous calcium carbonate were imprinted with calcite nucleation sites. The template-directed deposition and crystallization of the amorphous phase resulted in the fabrication of millimeter-sized single calcite crystals with sub-10-micron patterns and controlled crystallographic orientation. We suggest that in addition to regulating the shape, micropatterned frameworks act as sites for stress and impurity release during the amorphous-to-crystalline transition. The proposed mechanisms may have direct biological relevance and broad implications in materials synthesis.
487 citations
TL;DR: An approach that provides analytic expressions for the statistics of throughput of the mutual information of multiple-antenna systems with arbitrary correlations, interferers, and noise is presented and a method to analytically optimize over the input signal covariance is developed.
Abstract: The use of multiple-antenna arrays in both transmission and reception promises huge increases in the throughput of wireless communication systems. It is therefore important to analyze the capacities of such systems in realistic situations, which may include spatially correlated channels and correlated noise, as well as correlated interferers with known channel at the receiver. Here, we present an approach that provides analytic expressions for the statistics, i.e., the moments of the distribution, of the mutual information of multiple-antenna systems with arbitrary correlations, interferers, and noise. We assume that the channels of the signal and the interference are Gaussian with arbitrary covariance. Although this method is valid formally for large antenna numbers, it produces extremely accurate results even for arrays with as few as two or three antennas. We also develop a method to analytically optimize over the input signal covariance, which enables us to calculate analytic capacities when the transmitter has knowledge of the statistics of the channel (i.e., the channel covariance). In many cases of interest, this capacity is very close to the full closed-loop capacity, in which the transmitter has instantaneous channel knowledge. We apply this analytic approach to a number of examples and we compare our results with simulations to establish the validity of this approach. This method provides a simple tool to analyze the statistics of throughput for arrays of any size. The emphasis of this paper is on elucidating the novel mathematical methods used.
441 citations
TL;DR: These findings are likely indicative of a collective ground state previously unknown for 2DES, characterized by an exponentially vanishing low-temperature diagonal resistance and a classical Hall resistance.
Abstract: In an ultraclean 2D electron system (2DES) subjected to crossed millimeterwave (30--150 GHz) and weak ($Bl2\text{ }\mathrm{k}\mathrm{G}$) magnetic fields, a series of apparently dissipationless states emerges as the system is detuned from cyclotron resonances. Such states are characterized by an exponentially vanishing low-temperature diagonal resistance and a classical Hall resistance. The activation energies associated with such states exceed the Landau level spacing by an order of magnitude. Our findings are likely indicative of a collective ground state previously unknown for 2DES.
418 citations
411 citations
TL;DR: This work gives the first systematic study of the general class of equal-norm tight frames and their properties, and shows that the only equal- norm tight frames with the group structure and one or two generators are the generalized harmonic frames.
Abstract: Equal-norm tight frames have been shown to be useful for robust data transmission. The losses in the network are modeled as erasures of transmitted frame coefficients. We give the first systematic study of the general class of equal-norm tight frames and their properties. We search for efficient constructions of such frames. We show that the only equal-norm tight frames with the group structure and one or two generators are the generalized harmonic frames. Finally, we give a complete classification of frames in terms of their robustness to erasures.
392 citations
TL;DR: BothdH-PTTP and dH-PPTPP display a reversible, tunable, and stable memory effect even as solution-cast devices, with turn-on characteristics shifting from accumulation mode to zero or depletion mode after a writing voltage V(w).
Abstract: The synthesis of a new series of mixed phenylene−thiophene oligomers is reported; 2,5-bis(4-n-hexylphenyl)thiophene (dH-PTP, 1), 5,5‘-bis(4-n-hexylphenyl)-2,2‘-bithiophene (dH-PTTP, 2), 5,5‘ ‘-bis(4-n-hexylphenyl)-2,2‘:5‘,2‘ ‘-terthiophene (dH-PT3P, 3), 5,5‘ ‘‘-bis(4-n-hexylphenyl)-2,2‘:5‘,2‘ ‘:5‘ ‘,2‘ ‘‘-quaterthiophene (dH-PT4P, 4), 1,4-bis[5-(4-n-hexylphenyl)-2-thienyl]benzene (dH-PTPTP, 5), and 2,5-bis[4(4‘-n-hexylphenyl)phenyl]thiophene (dH-PPTPP, 6) were characterized by 1H NMR, elemental analysis, UV−visible spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. Vacuum-evaporated and solution-cast films were characterized by X-ray diffraction and scanning electron microscopy. All compounds display high p-type carrier mobilities as evaporated (up to 0.09 cm2/Vs) and as solution-cast (up to 0.03 cm2/Vs) films on both Si/SiO2 and ITO/GR (glass resin) substrates. The straightforwardly synthesized dH-PTTP (2) displays an unprecedented combination of mobility, on/off ratio, stab...
384 citations
14 Sep 2003
TL;DR: The approach that is used is quite flexible and is a promising method to handle more sophisticated interference conditions, multiple channels, multiple antennas, and routing with diversity requirements.
Abstract: This paper considers the problem of determining the achievable rates in multi-hop wireless networks. We consider the problem of jointly routing the flows and scheduling transmissions to achieve a given rate vector. We develop tight necessary and sufficient conditions for the achievability of the rate vector. We develop efficient and easy to implement Fully Polynomial Time Approximation Schemes for solving the routing problem. The scheduling problem is a solved as a graph edge-coloring problem. We show that this approach guarantees that the solution obtained is within 67% of the optimal solution in the worst case and, in practice, is typically within about 80% of the optimal solution. The approach that we use is quite flexible and is a promising method to handle more sophisticated interference conditions, multiple channels, multiple antennas, and routing with diversity requirements.
TL;DR: This work generalizes the zero-forcing beamforming technique to the multiple receive antennas case and uses this as the baseline for the packet data throughput evaluation, and examines the long-term average throughputs that can be achieved using the proportionally fair scheduling algorithm.
Abstract: Recently, the capacity region of a multiple-input multiple-output (MIMO) Gaussian broadcast channel, with Gaussian codebooks and known-interference cancellation through dirty paper coding, was shown to equal the union of the capacity regions of a collection of MIMO multiple-access channels. We use this duality result to evaluate the system capacity achievable in a cellular wireless network with multiple antennas at the base station and multiple antennas at each terminal. Some fundamental properties of the rate region are exhibited and algorithms for determining the optimal weighted rate sum and the optimal covariance matrices for achieving a given rate vector on the boundary of the rate region are presented. These algorithms are then used in a simulation study to determine potential capacity enhancements to a cellular system through known-interference cancellation. We study both the circuit data scenario in which each user requires a constant data rate in every frame and the packet data scenario in which users can be assigned a variable rate in each frame so as to maximize the long-term average throughput. In the case of circuit data, the outage probability as a function of the number of active users served at a given rate is determined through simulations. For the packet data case, long-term average throughputs that can be achieved using the proportionally fair scheduling algorithm are determined. We generalize the zero-forcing beamforming technique to the multiple receive antennas case and use this as the baseline for the packet data throughput evaluation.
TL;DR: This work uses electron counting to measure directly the quantum dot's tunnelling rate and the occupational probabilities of its charge state and provides evidence in favour of long (10 µs or more) inelastic scattering times in nearly isolated dots.
Abstract: Nanostructures in which strong (Coulomb) interactions exist between electrons are predicted to exhibit temporal electronic correlations1. Although there is ample experimental evidence that such correlations exist2, electron dynamics in engineered nanostructures have been observed directly only on long timescales3. The faster dynamics associated with electrical currents or charge fluctuations4 are usually inferred from direct (or quasi-direct) current measurements. Recently, interest in electron dynamics has risen, in part owing to the realization that additional information about electronic interactions can be found in the shot noise5 or higher statistical moments6,7 of a direct current. Furthermore, interest in quantum computation has stimulated investigation of quantum bit (qubit) readout techniques8,9, which for many condensed-matter systems ultimately reduces to single-shot measurements of individual electronic charges. Here we report real-time observation of individual electron tunnelling events in a quantum dot using an integrated radio-frequency single-electron transistor10,11. We use electron counting to measure directly the quantum dot's tunnelling rate and the occupational probabilities of its charge state. Our results provide evidence in favour of long (10 µs or more) inelastic scattering times in nearly isolated dots.
TL;DR: In this paper, loop complexes are used to inhibit the hybridization of complementary oligonucleotides, and rationally designed DNA catalysts are shown to be effective in promoting their hybridization.
Abstract: We describe kinetic control of DNA hybridization: loop complexes are used to inhibit the hybridization of complementary oligonucleotides; rationally designed DNA catalysts are shown to be effective in promoting their hybridization. This is the basis of a strategy for using DNA as a fuel to drive free-running artificial molecular machines.
TL;DR: It is shown that the performance of recently proposed quasi-orthogonal space-time codes can be improved by phase-shifting the constellations of the symbols constituting the code, leading to substantially improved performance.
Abstract: In this letter, we show that the performance of recently proposed quasi-orthogonal space-time codes can be improved by phase-shifting the constellations of the symbols constituting the code. The optimal rotation of the symbols increases the minimum distance of the corresponding space-time codewords, leading to substantially improved performance.
TL;DR: Polymerase chain reaction analysis yielded the first direct proof of DNA unzipped in such a system, and the enthalpy barriers to unzipping and the effective charge of a nucleotide in the pore were considerably smaller than previously assumed.
Abstract: We studied the unzipping of single molecules of double-stranded DNA by pulling one of their two strands through a narrow protein pore. Polymerase chain reaction analysis yielded the first direct proof of DNA unzipping in such a system. The time to unzip each molecule was inferred from the ionic current signature of DNA traversal. The distribution of times to unzip under various experimental conditions fit a simple kinetic model. Using this model, we estimated the enthalpy barriers to unzipping and the effective charge of a nucleotide in the pore, which was considerably smaller than previously assumed.
TL;DR: The main ideas of reduction-order modelling techniques based on Krylov subspaces are reviewed and some applications of reduced- order modelling in circuit simulation are described.
Abstract: In recent years, reduced-order modelling techniques based on Krylov-subspace iterations, especially the Lanczos algorithm and the Arnoldi process, have become popular tools for tackling the large-scale time-invariant linear dynamical systems that arise in the simulation of electronic circuits. This paper reviews the main ideas of reduced-order modelling techniques based on Krylov subspaces and describes some applications of reduced-order modelling in circuit simulation.
TL;DR: It is inferred that mammals encode social and reproductive information by integrating vomeronasal sensory activity specific to sex and genetic makeup.
Abstract: Many mammalian species rely on pheromones-semiochemicals produced by other members of the same species-to communicate social status and reproductive readiness. To assess how the central nervous system integrates the complex repertoire of pheromones, we recorded from single neurons in the accessory olfactory bulb, a nucleus that processes pheromonal signals, of male mice engaged in natural behaviors. Neuronal firing was robustly modulated by physical contact with male and female conspecifics, with individual neurons activated selectively by specific combinations of the sex and strain of conspecifics. We infer that mammals encode social and reproductive information by integrating vomeronasal sensory activity specific to sex and genetic makeup.
TL;DR: This paper investigates two models of accuracy-based learning classifier systems on different types of classification problems, and provides a model on the learning complexity of LCS which is based on the representative examples given to the system.
Abstract: Recently, Learning Classifier Systems (LCS) and particularly XCS have arisen as promising methods for classification tasks and data mining. This paper investigates two models of accuracy-based learning classifier systems on different types of classification problems. Departing from XCS, we analyze the evolution of a complete action map as a knowledge representation. We propose an alternative, UCS, which evolves a best action map more efficiently. We also investigate how the fitness pressure guides the search towards accurate classifiers. While XCS bases fitness on a reinforcement learning scheme, UCS defines fitness from a supervised learning scheme. We find significant differences in how the fitness pressure leads towards accuracy, and suggest the use of a supervised approach specially for multi-class problems and problems with unbalanced classes. We also investigate the complexity factors which arise in each type of accuracy-based LCS. We provide a model on the learning complexity of LCS which is based on the representative examples given to the system. The results and observations are also extended to a set of real world classification problems, where accuracy-based LCS are shown to perform competitively with respect to other learning algorithms. The work presents an extended analysis of accuracy-based LCS, gives insight into the understanding of the LCS dynamics, and suggests open issues for further improvement of LCS on classification tasks.
TL;DR: In this article, the use of nanotransfer printing (nTP) for forming 3D structures with feature sizes between tens of nanometers and tens of microns over areas of several square millimeters is described.
Abstract: This letter describes the use of nanotransfer printing (nTP) for forming three-dimensional (3D) structures with feature sizes between tens of nanometers and tens of microns over areas of several square millimeters. We demonstrate three different approaches-deep etching through printed hard masks, direct transfer of three-dimensional structures, and purely additive fabrication of multilayer stacks-for using nTP to fabricate a range of complex 3D nanostructures, including closed channels, suspended beams, and nanochannel stacks, that would be difficult or impossible to build with other methods.
TL;DR: A chemically modified poly(dimethylsiloxane) material is introduced here that is designed and optimized specifically for soft lithography, particularly in the nanometer regime, and used for nanopatterning tasks that are challenging with the commercially available elastomers.
Abstract: Patterning techniques that rely on high-resolution elastomeric elements such as stamps, molds, and conformable photomasks are operationally simple methods for nanofabrication that may find applicat...
TL;DR: In this article, a detailed study of the electrical properties of soft contact laminations of organic transistors is presented, with an emphasis on the nature of the laminated contacts with the p-and n-type semiconductors pentacene and copper hexadecafluorophthalocyanine, respectively.
Abstract: Soft contact lamination of source/drain electrodes supported by gold-coated high-resolution rubber stamps against organic semiconductor films can yield high-performance organic transistors. This article presents a detailed study of the electrical properties of these devices, with an emphasis on the nature of the laminated contacts with the p- and n-type semiconductors pentacene and copper hexadecafluorophthalocyanine, respectively. The analysis uses models developed for characterizing amorphous silicon transistors. The results demonstrate that the parasitic resistances related to the laminated contacts and their coupling to the transistor channel are considerably lower than those associated with conventional contacts formed by evaporation of gold electrodes directly on top of the organic semiconductors. These and other attractive features of transistors built by soft contact lamination suggest that they may be important for basic and applied studies in plastic electronics and nanoelectronic systems based ...
TL;DR: An ultrahigh-resolution optical coherence tomographic system in which broadband continuum generation from a photonic crystal fiber is used to produce high longitudinal resolution is developed and subcellular imaging is demonstrated.
Abstract: We have developed an ultrahigh-resolution optical coherence tomographic system in which broadband continuum generation from a photonic crystal fiber is used to produce high longitudinal resolution. Longitudinal resolution of 1.3-microm has been achieved in a biological tissue by use of continuum light from 800 to 1400 nm. The system employed a dynamic-focusing tracking method to maintain high lateral resolution over a large imaging depth. Subcellular imaging is demonstrated.
TL;DR: The emphasis will be on the operation of toeholds, single-stranded sections of DNA that facilitate the process of strand removal during certain points in the operationof a DNA-based motor.
Abstract: DNA hybridization has been used to power a number of DNA-based nanostructures constructed out of DNA. Here some considerations that go into DNA-based motor design are briefly reviewed. The emphasis will be on the operation of toeholds, single-stranded sections of DNA that facilitate the process of strand removal during certain points in the operation of a DNA-based motor. Reaction kinetics measurements for toehold mediated strand exchange are reported. These measurements have served as a guide for choosing toehold lengths.
TL;DR: In this paper, thermal imaging is used to pattern a range of organic materials at high speed over large areas with micron size resolution and excellent electrical performance avoiding the solvent compatibility issues currently faced by alternative techniques.
Abstract: We show here that thermal imaging, a nonlithographic technique which enables printing multiple, successive layers via a dry additive process can be used in combination with tailored printable conductors in the fabrication of organic electronic devices. This method is capable of patterning a range of organic materials at high speed over large areas with micron size resolution and excellent electrical performance avoiding the solvent compatibility issues currently faced by alternative techniques. Such a dry, potentially reel-to-reel printing method may provide a practical route to realizing the expected benefits of plastics for electronics. We illustrate the viability of thermal imaging and imageable organics conductors by printing a functioning, large area (4000 cm2) active matrix backplane display circuit containing several thousand transistors.
01 Jan 2003
TL;DR: Network devices put packets on an Internet link, and multiplex, or superpose, the packets from different active connections.
Abstract: Network devices put packets on an Internet link, and multiplex, or superpose, the packets from different active connections.
TL;DR: A comprehensive classification of dirty data is developed for use as a framework for understanding how dirty data arise, manifest themselves, and may be cleansed to ensure proper construction of data warehouses and accurate data analysis.
Abstract: Today large corporations are constructing enterprise data warehouses from disparate data sources in order to run enterprise-wide data analysis applications, including decision support systems, multidimensional online analytical applications, data mining, and customer relationship management systems. A major problem that is only beginning to be recognized is that the data in data sources are often “dirty”. Broadly, dirty data include missing data, wrong data, and non-standard representations of the same data. The results of analyzing a database/data warehouse of dirty data can be damaging and at best be unreliable. In this paper, a comprehensive classification of dirty data is developed for use as a framework for understanding how dirty data arise, manifest themselves, and may be cleansed to ensure proper construction of data warehouses and accurate data analysis. The impact of dirty data on data mining is also explored.
TL;DR: The miniaturization and tailorable emission properties of this design are potentially important for sensing applications, while electrical pumping can allow new studies of photonic crystal and surface plasmon structures in nonlinear and near-field optics.
Abstract: We combine photonic and electronic band structure engineering to create a surface-emitting quantum cascade microcavity laser. A high-index contrast two-dimensional photonic crystal is used to form a micro-resonator that simultaneously provides feedback for laser action and diffracts light vertically from the surface of the semiconductor surface. A top metallic contact allows electrical current injection and provides vertical optical confinement through a bound surface plasmon wave. The miniaturization and tailorable emission properties of this design are potentially important for sensing applications, while electrical pumping can allow new studies of photonic crystal and surface plasmon structures in nonlinear and near-field optics.
Patent•
12 Dec 2003TL;DR: In this article, a virtual router network (VRN) for performing real-time flow measurements (RTFM) is provided, which effectively reduces the number of traffic metering points required thereby simplifying the aggregation and exportation of flow records to a collector.
Abstract: A virtual router network (VRN) for performing real-time flow measurements (RTFM) is provided. The VRN effectively reduces the number of traffic metering points required thereby simplifying the aggregation and exportation of flow records to a collector. The collector may be service manager in a network management system. The metering points, in a preferred embodiment, are at virtual interfaces (VI) which are edge nodes in VRN. One of the virtual interfaces is selected as a master virtual interface and act as a collector and distributor of flow related information. In one aspect of the invention the VRN is used to provide, non-invasively, per-flow delay monitoring in a communication system.