Showing papers by "NEC published in 2013"

Interference Management in Femtocells

Abstract: Increase in system capacity and data rates can be achieved efficiently in a wireless system by getting the transmitter and receiver closer to each other. Femtocells deployed in the macrocell significantly improve the indoor coverage and provide better user experience. The femtocell base station called as Femtocell Access Point (FAP) is fully user deployed and hence reduces the infrastructure, maintenance and operational cost of the operator while at the same time providing good Quality of Service (QoS) to the end user and high network capacity gains. However, the mass deployment of femtocell faces a number of challenges, among which interference management is of much importance, as the fundamental limits of capacity and achievable data rates mainly depends on the interference faced by the femtocell network. To cope with the technical challenges including interference management faced by the femtocells, researchers have suggested a variety of solutions. These solutions vary depending on the physical layer technology and the specific scenarios considered. Furthermore, the cognitive capabilities, as a functionality of femtocell have also been discussed in this survey. This article summarises the main concepts of femtocells that are covered in literature and the major challenges faced in its large scale deployment. The main challenge of interference management is discussed in detail with its types in femtocells and the solutions proposed over the years to manage interference have been summarised. In addition an overview of the current femtocell standardisation and the future research direction of femtocells have also been provided.

In silico discovery of small-molecule Ras inhibitors that display antitumor activity by blocking the Ras-effector interaction.

Abstract: Mutational activation of the Ras oncogene products (H-Ras, K-Ras, and N-Ras) is frequently observed in human cancers, making them promising anticancer drug targets. Nonetheless, no effective strategy has been available for the development of Ras inhibitors, partly owing to the absence of well-defined surface pockets suitable for drug binding. Only recently, such pockets have been found in the crystal structures of a unique conformation of Ras⋅GTP. Here we report the successful development of small-molecule Ras inhibitors by an in silico screen targeting a pocket found in the crystal structure of M-Ras⋅GTP carrying an H-Ras–type substitution P40D. The selected compound Kobe0065 and its analog Kobe2602 exhibit inhibitory activity toward H-Ras⋅GTP-c-Raf-1 binding both in vivo and in vitro. They effectively inhibit both anchorage-dependent and -independent growth and induce apoptosis of H-rasG12V–transformed NIH 3T3 cells, which is accompanied by down-regulation of downstream molecules such as MEK/ERK, Akt, and RalA as well as an upstream molecule, Son of sevenless. Moreover, they exhibit antitumor activity on a xenograft of human colon carcinoma SW480 cells carrying the K-rasG12V gene by oral administration. The NMR structure of a complex of the compound with H-Ras⋅GTPT35S, exclusively adopting the unique conformation, confirms its insertion into one of the surface pockets and provides a molecular basis for binding inhibition toward multiple Ras⋅GTP-interacting molecules. This study proves the effectiveness of our strategy for structure-based drug design to target Ras⋅GTP, and the resulting Kobe0065-family compounds may serve as a scaffold for the development of Ras inhibitors with higher potency and specificity.

Antenna device and method for attaching the same

Abstract: An antenna device includes: a radio device for radio wave transmission; a primary radiator that has a function to radiates radio waves generated by the radio device; a parabolic reflector that reflects the radio waves radiated from the primary radiator; a shroud that shields against unnecessary radiation radio waves among the radio waves radiated from the primary radiator and reflected by the parabolic reflector; and an antenna mounting mechanism that fits the parabolic reflector to an antenna attachment pole. The shroud is arranged so as to cover at least a right and left of the parabolic reflector, the radio device and the primary radiator are arranged inside the shroud, and the antenna mounting mechanism fits the parabolic reflector to the antenna attachment pole so that the antenna attachment pole is located at a lateral center position of the parabolic reflector.

Repeater, excitation light supply device used for the same, and excitation light supply method

Abstract: Even when some light emitting elements among the plurality of light emitting elements fail, a repeater, can be continuously operated. Means for solving the problems A light source unit 50 which includes a plurality of pumping light source modules 51 ( 51 a to 51 d ) which include light emitting elements 52 ( 52 a to 52 d ) for emitting an excitation light and monitor elements 53 ( 53 a to 53 d ) for monitoring the excitation lights of the light emitting elements 52 ( 52 a to 52 d ), respectively, a distribution unit 40 which combines the excitation lights from the plurality of pumping light source modules 51 ( 51 a to 51 d ) and distributes it, and a control unit 60 which supplies a drive current flowing serially through the plurality of light emitting elements 52 ( 52 a to 52 d ) in a plurality of excitation modules 51 ( 51 a to 51 d ) are included.

Communication system, base station, and communication method

Abstract: Disclosed is a communication system in which information about the number of active users in each cell can be shared between base stations A communication system according to the present exemplary embodiment includes a first base station controlling a first cell and a second base station connected to the first base station through an inter-base-station interface, wherein the first base station transmits operation information on the first cell to the second base station through the inter-base-station interface, wherein the operation information on the first cell includes information about a load on the first cell and information about the number of active users in the first cell

$\mathcal{MD}$-HBase: design and implementation of an elastic data infrastructure for cloud-scale location services

Abstract: The ubiquity of location enabled devices has resulted in a wide proliferation of location based applications and services. To handle the growing scale, database management systems driving such location based services (LBS) must cope with high insert rates for location updates of millions of devices, while supporting efficient real-time analysis on latest location. Traditional DBMSs, equipped with multi-dimensional index structures, can efficiently handle spatio-temporal data. However, popular open-source relational database systems are overwhelmed by the high insertion rates, real-time querying requirements, and terabytes of data that these systems must handle. On the other hand, key-value stores can effectively support large scale operation, but do not natively provide multi-attribute accesses needed to support the rich querying functionality essential for the LBSs. We present the design and implementation of $\mathcal {MD}$ -HBase, a scalable data management infrastructure for LBSs that bridges this gap between scale and functionality. Our approach leverages a multi-dimensional index structure layered over a key-value store. The underlying key-value store allows the system to sustain high insert throughput and large data volumes, while ensuring fault-tolerance, and high availability. On the other hand, the index layer allows efficient multi-dimensional query processing. Our optimized query processing technique accesses only the index and storage level entries that intersect with the query region, thus ensuring efficient query processing. We present the design of $\mathcal {MD}$ -HBase that demonstrates how two standard index structures--the K-d tree and the Quad tree--can be layered over a range partitioned key-value store to provide scalable multi-dimensional data infrastructure. Our prototype implementation using HBase, a standard open-source key-value store, can handle hundreds of thousands of inserts per second using a modest 16 node cluster, while efficiently processing multi-dimensional range queries and nearest neighbor queries in real-time with response times as low as few hundreds of milliseconds.

Advanced wireless and optical technologies for small-cell mobile backhaul with dynamic software-defined management

Abstract: This article discusses novel wireless and optical technologies to address the radical new challenges of small cell mobile backhaul (MBH). Specifically, we examine 60 GHz and 70-80 GHz millimeter-wave technologies for high-capacity last mile and pre-aggregation backhaul, and orthogonal frequency-division multiple access passive optical networks as the optical technology complement for enabling flexible cost-efficient hybrid backhaul coverage. Flexible high-capacity hybrid millimeter wave/optical MBH network operation is next verified via network simulations in the context of a demanding, urban small-cell backhaul application. Finally, a novel software defined networking tool called the backhaul resource manager is introduced for automated dynamic resource provisioning and capacity-aware path computation that improves fairness, network utilization and end-to-end user quality of experience. The introduction of the novel wireless, optical, and software-defined technologies thus has the potential to truly revolutionize the future MBH network.

Coordinated Bank and Cache Coloring for Temporal Protection of Memory Accesses

Abstract: In commercial-off-the-shelf (COTS) multi-core systems, the execution times of tasks become hard to predict because of contention on shared resources in the memory hierarchy. In particular, a task running in one processor core can delay the execution of another task running in another processor core. This is due to the fact that tasks can access data in the same cache set shared among processor cores or in the same memory bank in the DRAM memory (or both). Such cache and bank interference effects have motivated the need to create isolation mechanisms for resources accessed by more than one task. One popular isolation mechanism is cache coloring that divides the cache into multiple partitions. With cache coloring, each task can be assigned exclusive cache partitions, thereby preventing cache interference from other tasks. Similarly, bank coloring allows assigning exclusive bank partitions to tasks. While cache coloring and some bank coloring mechanisms have been studied separately, interactions between the two schemes have not been studied. Specifically, while memory accesses to two different bank colors do not interfere with each other at the bank level, they may interact at the cache level. Similarly, two different cache colors avoid cache interference but may not prevent bank interference. Therefore it is necessary to coordinate cache and bank coloring approaches. In this paper, we present a coordinated cache and bank coloring scheme that is designed to prevent cache and bank interference simultaneously. We also developed color allocation algorithms for configuring a virtual memory system to support our scheme which has been implemented in the Linux kernel. In our experiments, we observed that the execution time can increase by 60% due to inter-task interference when we use only cache coloring. Our coordinated approach can reduce this figure down to 12% (an 80% reduction).

A 1 Mb Nonvolatile Embedded Memory Using 4T2MTJ Cell With 32 b Fine-Grained Power Gating Scheme

Abstract: A 1 Mb nonvolatile embedded memory using a four transistor and two spin-transfer-torque (STT) magnetic tunnel junction (MTJ) cell is designed and fabricated to demonstrate its zero standby power and high performance. The power supply voltages of 32 cells along a word line (WL) are controlled simultaneously by a power line (PL) driver to eliminate the standby power without impact on the access time. This fine-grained power gating scheme also optimizes the trade-off between macro size and operation power. The butterfly curve for the cell is measured to be asymmetric as predicted, enhancing the cell's static noise margin (SNM) for data retention. The scaling of 1 Mb macro size is compared with that of the 6T SRAM counterpart, indicating that the former will become smaller than the latter at 45 nm technology node and beyond by moderately thinning its tunnel dielectrics (MgO) in accordance with the shrink of the MTJ's cross sectional area. The operation current of the macro is also shown to be almost unchanged over generations, while that of the 6T SRAM increases exponentially due to the degradation of MOSFET off-current as the device scales.

Neutrophil infiltration during inflammation is regulated by PILRα via modulation of integrin activation

Abstract: Acute inflammatory responses are important in host defense, whereas dysregulated inflammation results in life-threatening complications. Here we found that paired immunoglobulin-like type 2 receptor alpha (PILRα), an inhibitory receptor containing immunoreceptor tyrosine-based inhibitory motifs (ITIMs), negatively regulated neutrophil infiltration during inflammation. Pilra(-/-) mice had increased neutrophil recruitment to inflammatory sites and were highly susceptible to endotoxin shock. Pilra(-/-) neutrophils showed enhanced transmigration ability and increased adhesion to the β(2) integrin ligand ICAM-1. PILRα expressed on neutrophils constitutively associated in cis with its ligands, resulting in clustering of PILRα during stimulation with a chemoattractant. Clustering of PILRα enhanced ITIM-mediated signaling, thus modulating β(2) integrin inside-out activation. These data demonstrate that neutrophil recruitment in inflammatory responses is regulated by PILRα via modulation of integrin activation.

First demonstration of MC-EDFA-repeatered SDM transmission of 40 x 128-Gbit/s PDM-QPSK signals per core over 6,160-km 7-core MCF.

Abstract: We demonstrate the first 7-core multicore erbium-doped fiber amplified (MC-EDFA) transmission of 40 x 128-Gbit/s PDM-QPSK signals over 6,160-km 7-core multicore fiber (MCF). The crosstalk (XT) from all of the other 6 cores of a MC-EDFA and a 55-km length MCF are about -46.5 dB and -45.6 dB at center core, respectively. The core-to-core rotation approach at every amplified span is used to average the XT of all cores. The averaged optical signal-to-noise ratio (OSNR) after 6,160-km transmission is 15.6 dB with 0.1 nm resolution bandwidth. The Q-factor of all 40 channels surpasses the threshold of the forward-error-correction of 6.4 dB with 1 dB margin after 6,160 km. The total net capacity is 28.8 Tbit/s per fiber and achieved capacity-distance product is 177 Pbit/s.km per fiber. We confirmed the feasibility of MC-EDFA repeatered systems for trans-oceanic transmission.

Coherent flux tunneling through NbN nanowires

Abstract: We demonstrate evidence of coherent magnetic flux tunneling through superconducting nanowires patterned in a thin highly disordered NbN film. The phenomenon is revealed as a superposition of flux states in a fully metallic superconducting loop with the nanowire acting as an effective tunnel barrier for the magnetic flux, and reproducibly observed in different wires. The flux superposition achieved in the fully metallic NbN rings proves the universality of the phenomenon previously reported for InO x . We perform microwave spectroscopy and study the tunneling amplitude as a function of the wire width, compare the experimental results with theories, and estimate the parameters for existing theoretical models.

Blood Cell-Derived Induced Pluripotent Stem Cells Free of Reprogramming Factors Generated by Sendai Viral Vectors

Abstract: The discovery of induced pluripotent stem cells (iPSCs) holds great promise for regenerative medicine since it is possible to produce patient-specific pluripotent stem cells from affected individuals for potential autologous treatment. Using nonintegrating cytoplasmic Sendai viral vectors, we generated iPSCs efficiently from adult mobilized CD34+ and peripheral blood mononuclear cells. After 5–8 passages, the Sendai viral genome could not be detected by real-time quantitative reverse transcription-polymerase chain reaction. Using the spin embryoid body method, we showed that these blood cell-derived iPSCs could efficiently be differentiated into hematopoietic stem and progenitor cells without the need of coculture with either mouse or human stromal cells. We obtained up to 40% CD34+ of which ∼25% were CD34+/CD43+ hematopoietic precursors that could readily be differentiated into mature blood cells. Our study demonstrated a reproducible protocol for reprogramming blood cells into transgene-free iPSCs by the Sendai viral vector method. Maintenance of the genomic integrity of iPSCs without integration of exogenous DNA should allow the development of therapeutic-grade stem cells for regenerative medicine.

Maintenance-free operation of WDM quantum key distribution system through a field fiber over 30 days.

Abstract: Maintenance-free wavelength-division-multiplexing quantum key distribution for 30 days was achieved through a 22-km field fiber. Using polarization-independent interferometers and stabilization techniques, we attained a quantum bit error rate as low as 1.70% and an estimated secure key rate as high as 112.4 kbps for a record-breaking 291.3 Gbits of estimated secure keys accumulated over an uninterrupted operation period.

Radio communication system and communication method

Abstract: A radio communication system includes a plurality of base stations with supporting a plurality of radio access schemes. Two or more base stations support a predetermined radio access scheme in common. A mobile station makes initial connection to one of the two or more base stations according to the predetermined radio access scheme, to allow communication with the one base station.

Single-shot readout of a superconducting flux qubit with a flux-driven Josephson parametric amplifier

Abstract: We report single-shot readout of a superconducting flux qubit by using a flux-driven Josephson parametric amplifier (JPA). After optimizing the readout power, gain of the JPA, and timing of the data acquisition, we observe the Rabi oscillations with a contrast of 74%, which is mainly limited by the bandwidth of the JPA and the energy relaxation of the qubit. The observation of quantum jumps between the qubit eigenstates under continuous monitoring indicates the nondestructiveness of the readout scheme.

Computer system and virtual network visualization method

Abstract: A computer system according to the present invention includes a managing unit which outputs a plurality of virtual networks managed by a plurality of controllers in a visually perceivable form with the plurality of virtual networks combined, on the basis of topology data of the virtual networks, the topology data being generated based on communication routes. This enables centralized management of the whole of a virtual network controlled by a plurality of controllers which use an OpenFlow technology.

Observation of the three-state dressed states in circuit quantum electrodynamics.

Abstract: We have investigated the microwave response of a transmon qubit coupled directly to a transmission line. In a transmon qubit, owing to its weak anharmonicity, a single driving field may generate dressed states involving more than two bare states. We confirmed the formation of three-state dressed states by observing all of the six associated Rabi sidebands, which appear as either amplification or attenuation of the probe field. The experimental results are reproduced with good precision by a theoretical model incorporating the radiative coupling between the qubit and the microwave.

Design principles of an operator-owned highly distributed content delivery network

Abstract: Mobile network operators are experiencing a tremendous increase in data traffic due to the growing popularity of bandwidth-intensive video services. This challenge can be faced either by boosting the capacity of the network infrastructure, or by means of offloading traffic from the backhaul and core network and serving contents from distributed cache servers close to the users. Network operators can extend the coverage of traditional CDNs by making usage of caching locations much closer to the users than traditional CDNs. Additionally, network operators can optimize the caching and delivery of contents by exploiting the complete knowledge of their network for designing a cost-effective infrastructure able to achieve both improved user satisfaction and cost savings. This article provides thoroughly justified design principles for a highly distributed operator-owned CDN while focusing on four key aspects: the optimal location of cache servers, mechanisms for request routing, content replica placement, and content outsourcing and retrieval.

Reduction of influence of inter-core cross-talk in MCF with bidirectional assignment between neighboring cores

Abstract: We evaluated the effects of bidirectional signal assignment between neighboring cores in MCF for the reduction of inter-core cross-talk with 98-km MCF. We clarify its advantage and several specific limiting factors.

20-nm magnetic domain wall motion memory with ultralow-power operation

Abstract: We study the write and retention properties of magnetic domain wall (DW)-motion memory devices with the dimensions down to 20 nm. We find that the write current and time are scaled along with device size while sufficient thermal stability and low error rate are maintained. As a result, ultralow-power (a few fJ) and reliable operation is possible even at reduced dimensions.

Automated gastric cancer diagnosis on HE ltraining a classifier on a large scale with multiple instance machine learning

Abstract: We present a system that detects cancer on slides of gastric tissue sections stained with hematoxylin and eosin (H&E). At its heart is a classifier trained using the semi-supervised multi-instance learning framework (MIL) where each tissue is represented by a set of regions-of-interest (ROI) and a single label. Such labels are readily obtained because pathologists diagnose each tissue independently as part of the normal clinical workflow. From a large dataset of over 26K gastric tissue sections from over 12K patients obtained from a clinical load spanning several months, we train a MIL classifier on a patient-level partition of the dataset (2/3 of the patients) and obtain a very high performance of 96% (AUC), tested on the remaining 1/3 never-seen before patients (over 8K tissues). We show this level of performance to match the more costly supervised approach where individual ROIs need to be labeled manually. The large amount of data used to train this system gives us confidence in its robustness and that it can be safely used in a clinical setting. We demonstrate how it can improve the clinical workflow when used for pre-screening or quality control. For pre-screening, the system can diagnose 47% of the tissues with a very low likelihood (< 1%) of missing cancers, thus halving the clinicians' caseload. For quality control, compared to random rechecking of 33% of the cases, the system achieves a three-fold increase in the likelihood of catching cancers missed by pathologists. The system is currently in regular use at independent pathology labs in Japan where it is used to double-check clinician's diagnoses. At the end of 2012 it will have analyzed over 80,000 slides of gastric and colorectal samples (200,000 tissues).

Single-shot readout of a superconducting flux qubit with a flux-driven Josephson parametric amplifier

Abstract: We report single-shot readout of a superconducting flux qubit by using a flux-driven Josephson parametric amplifier (JPA). After optimizing the readout power, gain of the JPA and timing of the data acquisition, we observe the Rabi oscillations with a contrast of 74% which is mainly limited by the bandwidth of the JPA and the energy relaxation of the qubit. The observation of quantum jumps between the qubit eigenstates under continuous monitoring indicates the nondestructiveness of the readout scheme.

Lithium secondary cell

Abstract: Provided is a lithium secondary cell of 5V class having a positive electrode operating voltage of 45V or higher with respect to metallic lithium; the lithium secondary cell has high energy density, inhibits degradation of the electrolytic solution that comes in contact with the positive electrode and the negative electrode, and has particularly long cell life when used under high-temperature environments The positive electrode contains, as the positive electrode active substance, a predetermined lithium-manganese oxide complex; the negative electrode contains, as the negative electrode active substance, graphite, of which surface is coated by low-crystallinity carbon; and the electrolytic solution contains one or more high-oxidation-potential solvents selected from propylene carbonate, butylene carbonate, 4-fluoro-1,3-dioxolan-2-one, and 4,5-difluoro-1,3-dioxolan-2-one within a range of 5 to 60 vol% of the solvent and one or two low-viscosity solvents selected from dimethyl carbonate and fluorinated cyclic ether

Silicon-based electro-optical device

Abstract: In an electro-optic device, a stack structure including a first silicon layer of a first conductivity type and a second silicon layer of a second conductivity type has a rib waveguide shape so as to form an optical confinement area, and a slab portion of a rib waveguide includes an area to which a metal electrode is connected. The slab portion in the area to which the metal electrode is connected is thicker than a surrounding slab portion. The area to which the metal electrode is connected is set so that a range of a distance from the rib waveguide to the area to which the metal electrode is connected is such that when the distance is changed, an effective refractive index of the rib waveguide in a zeroth-order mode does not change.

Map matching system, map matching method and program

Abstract: Provided is a map matching device, method and program. The map matching device may comprise a road grid dividing unit and a grid road combining unit. The road grid dividing unit is for deriving a grid obtained by the division of a region where a road network exists in a latitude direction and a longitude direction by equal spaces and correlating the grid and an arc crossing the grid. The grid road combining unit is for assigning a common arc ID to a plurality of grids which are adjacent to each other and whose sets of arcs correlated are coincident and assigning an arc ID to a grid whose set of arcs correlated is different from a set of arcs of any of adjacent grids to generate information indicative of a relationship among a range of a grid, a grid ID and an arc passing the grid.

Phase randomization - A new paradigm for single-channel signal enhancement

Abstract: This paper proposes a new paradigm with phase randomization for single-channel signal enhancement. In contrast to literatures which pursue better target signal quality, the new method tries to minimize artifacts in the residual noise. Applications of signal enhancement are revisited to highlight today's examples where environmental signal is often considered as a part of target and SNR may take a negative value. A signal example demonstrates that conventional signal enhancement with magnitude-only modification is insufficient from both objective and subjective points of view. A new framework with phase randomization as well as a specific algorithm is developed. Enhanced signals show that phase randomization is an integral component for sufficient enhancement. A subjective evaluation result demonstrates that the new paradigm with phase randomization is superior to the magnitude-only enhancement with statistically significant differences.