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Long-duration quantum memories for photonic qubits are essential components for achieving long-distance quantum networks and repeaters. The mapping of optical states onto coherent spin-waves in rare earth ensembles is a particularly promising approach to quantum storage. However, it remains challenging to achieve long-duration storage at the quantum level due to read-out noise caused by the required spin-wave manipulation. In this work, we apply dynamical decoupling techniques and a small magnetic field to achieve the storage of six temporal modes for 20, 50, and 100 ms in a 151Eu3+:Y2SiO5 crystal, based on an atomic frequency comb memory, where each temporal mode contains around one photon on average. The quantum coherence of the memory is verified by storing two time-bin qubits for 20 ms, with an average memory output fidelity of F = (85 ± 2)% for an average number of photons per qubit of μin = 0.92 ± 0.04. The qubit analysis is done at the read-out of the memory, using a type of composite adiabatic read-out pulse we developed. [ABSTRACT FROM AUTHOR]

In all Hard IP (HIP) designs, there is a need for signals to travel from its source to destination module. To meet timing, they are flop repeated based on the floorplan of the design. Different signals have unique repetition requirements based on their functionality/timing criticality. Also signals may have single destination or multiple destinations. The flop repeater structure for each signal should be optimized so that it has minimum number of flops and timing is also met, to achieve desired targets for timing, area and power. This paper will show how we are creating optimized tree structure based on mathematical techniques and generating automated RTL for such repeater flop module. This submission presents a new tool ART (Auto Repeater Tool) that completely eliminates the manual effort/time required to generate functional, ready to plug-in RTL. [ABSTRACT FROM AUTHOR]

A novel and highly accurate finite-difference time-domain model is developed for bundled single-walled carbon nanotube (SWCNT) interconnects by considering a fixed configuration that consists of a CMOS driver, a bundled SWCNT interconnect system, and an optimal number of repeaters. Using superposition theorem, this iterative model is applied to the entire chain of repeaters to calculate the total closed-loop delay. An accurate transfer function is modeled for the chain of equi-spaced repeaters in the interconnect system. The transfer function is further used to develop an analytical model for closed-loop delay, considering the optimum number of repeaters as dependent parameter. Further, in order to determine the minimum delay, an analysis is performed to find out the optimum number of repeaters for a given interconnect length. In addition, a detailed study is carried out to observe the impact of interconnect length on time delay, the time delay reduction on increasing the number of repeaters and the effect of excitation magnitude on time delay with power delay product. It is observed that by using SWCNT interconnects, the total number of repeaters and the time delay are reduced by more than 40 and 50%, respectively, compared with the copper (Cu) interconnects. However, the proposed model achieves extreme accuracy, with 4% relative tolerance at maximum, in predicting interconnect performance based on comparison with the HSPICE simulations. [ABSTRACT FROM AUTHOR]

Industrial safety refers to the prevention of industrial accidents by limiting the factors that cause them. In other words, it encompasses all the activities required to safeguard and maintain industrial facilities and protect workers from all health issues caused by the disasters or accidents incurred by industrial activities. However, inadequate industrial safety education, a lack of preventative systems, and a lack of predictive facilities have led to frequent industrial accidents. These industrial accidents increase economic losses and lead to an increase also in the number of workers’ deaths and injuries. The objective of the study presented in this paper was therefore to develop a disaster prevention system to ensure the safety of workers in extreme industrial fields. In the system, peer-to-peer (P2P) sensor network technology is applied to allow the status of the worksite to be monitored in real time by the general management center, field manager, and workers in the industrial field. For the system, we developed a smartphone application that transmits the results of a harmful gas detection module and a workplace escape map, and designed a structure that connects the management center and field workers through a wireless communication repeater. In addition, we propose an integrated system that collects disaster information in real time through the P2P sensor network system. In the future, when disasters occur, the person in charge and the manager will be able to transmit information in real time, which will all owa rapid response to situations. [ABSTRACT FROM AUTHOR]

This paper presents an active cancellation method based on repeater jamming to weaken the incident wave rather than to weaken the scattered wave in conventional method. The method works well on chirp-subpulse stepped frequency (CSSF) signal. The incident plane wave is interfered by a spherical wave which is generated by a horizontal electric dipole. The analysis and simulation show that the plane wave can be reduced obviously via this method. By incorporating frequency and phase modulation, the backscattering of the target is reduced significantly. Numerical experiments also show that with greater wavelength, the cancellation performance gets better. [ABSTRACT FROM AUTHOR]

Closed-form expressions for the optimized number and size of repeaters in multi-walled carbon nanotube (MWCNT) interconnects are presented. The contact resistance and inductive effects are taken into account. It is found that the propagation delay of MWCNT interconnects can be reduced effectively by inserting repeaters. However, the contact resistance has a significant influence on the optimized number and size of repeaters. Moreover, it is found that both the optimal number of repeaters and the minimum propagation delay are kept almost unchanged with the variation of carbon nanotube (CNT) kinetic inductance. The optimal number of repeaters in the MWCNT interconnect is much smaller than that in its Cu counterpart, thus saving chip area and power consumption. [ABSTRACT FROM AUTHOR]

Dual-band coil modules facilitate efficient access to distinct-band, high-power, or rapid-charging wireless power transfer (WPT) systems. However, they do not function efficiently when the frequency ratio between two operating frequencies is large. To overcome this problem, we propose enhanced dual-band coil modules that adopt repeaters in the WPT system. We present a circuit-based analysis of repeaters in various dual-band coil modules compared with those in a single-band WPT system. The analytical results provide a design methodology applicable to diverse types of dual-band coil modules with a repeater in the WPT system. Our experimental results are consistent with the circuit-based analysis: coil power transfer efficiencies of 55% at 200 kHz and 74% at 6.78 MHz were obtained concurrently in the dual-band WPT system with a dual-band repeater. This paper reduced the application constraint of dual-band coil modules and facilitated the realization and application of multiband WPT systems. [ABSTRACT FROM PUBLISHER]

For frequency division duplex channels, a simple pilot loop-back procedure has been proposed that allows the estimation of the uplink (UL) and downlink (DL) channel subspaces between an antenna array and a fully analog repeater. For this scheme, we derive the maximum likelihood (ML) estimators for the UL and DL subspaces, formulate the corresponding Cramér–Rao bounds, and show the asymptotic efficiency of both (singular value decomposition (SVD) based) estimators by means of Monte Carlo simulations. In addition, we illustrate how to compute the underlying (rank-1) SVD with quadratic time complexity by employing the power iteration method. To enable power control for the data transmission, knowledge of the channel gains is needed. Assuming that the UL and DL channels have on average the same gain, we formulate the ML estimator for the uplink channel vector norm, and illustrate its robustness against strong noise perturbations by means of simulations. [ABSTRACT FROM PUBLISHER]

Interrupted-sampling repeater jamming (ISRJ) provides a novel coherent-jamming mode against wideband radar. ISRJ allows the single-antenna jammer to periodically sample and repeat a fraction of the intercepted signal, which reduces the sampling rate and achieves transmit-receive isolation. The coherent-jamming signal generated by ISRJ can form multiple verisimilar false targets when received and processed by the victim radar receiver. Moreover, some false targets can precede the real target. This paper surveys the use of ISRJ in linear frequency modulated (LFM) radar jamming. The theory and application of ISRJ has been researched for more than one decade, but what is missing is a completed summary for the framework of this technique. In this paper, mathematic principles of ISRJ against LFM radars, which utilize matched-filter processing, stretch processing, and range-Doppler processing, are developed. The unique jamming effects in radar systems are focused on when the interrupted sampling frequency of the jammer is smaller than the bandwidth of the radar signal. Specifically, the false-target characteristics, including amplitude, space distribution, and phase, are discussed, respectively. On this basis, the key jamming elements, which determine these false-target characteristics, are pointed out and analyzed in detail. At last, simulation and real data are used to verify the correctness of the analyses. Experimental results highlight the potential application of the proposed jamming mode. [ABSTRACT FROM PUBLISHER]

Wireless charging has provided a convenient alternative to renew nodes’ energy in wireless sensor networks. Due to physical limitations, previous works have only considered recharging a single node at a time, which has limited efficiency and scalability. Recent advances on multi-hop wireless charging is gaining momentum and provides fundamental support to address this problem. However, existing single-node charging designs do not consider and cannot take advantage of such opportunities. In this paper, we propose a new framework to enable multi-hop wireless charging using resonant repeaters. First, we present a realistic model that accounts for detailed physical factors to calculate charging efficiencies. Second, to achieve balance between energy efficiency and data latency, we propose a hybrid data gathering strategy that combines static and mobile data gathering to overcome their respective drawbacks and provide theoretical analysis. Then, we formulate multi-hop recharge schedule into a bi-objective NP-hard optimization problem. We propose a two-step approximation algorithm that first finds the minimum charging cost and then calculates the charging vehicles’ moving costs with bounded approximation ratios. Finally, upon discovering more room to reduce the total system cost, we develop a post-optimization algorithm that iteratively adds more stopping locations for charging vehicles to further improve the results while ensuring none of the nodes will deplete battery energy. Our extensive simulations show that the proposed algorithms can handle dynamic energy demands effectively, and can cover at least three times of nodes and reduce service interruption time by an order of magnitude compared to the single-node charging scheme. [ABSTRACT FROM AUTHOR]

Interrupted sampling repeater jamming (ISRJ) is an effective coherent jamming, which can induce false high-resolution range profile (HRRP) and image to greatly complicate the target detection and recognition of wideband radar. To counter ISRJ, an efficient filter is designed based on the time-frequency (TF) characteristic differences between target echo and ISRJ. Meanwhile, a feasible jamming suppression scheme is proposed, which not only could eliminate ISRJ but also could reserve the target echo. The main emphasis is that the received echo suppressed by our scheme is similar with the true target's HRRP on the basis of high correlation coefficient (CC) and large signal-jamming-to-noise ratio (SJNR) improvement factor. Simulation results are covered to illustrate the feasibility and validness of jamming suppression. [ABSTRACT FROM AUTHOR]

Since Feynman first proposed the idea of simulating a quantum system using another quantum system in 1981 [1], substantial progress has been made to control the individual quantum systems; now, many technology companies have become involved in quantum technology. SK Telecom has been developing various quantum technologies for the last five years, and an overview of the progress in the development of a quantum key distribution system, quantum random number generator chips, and a quantum repeater will be given in this article. [ABSTRACT FROM AUTHOR]

In the literature, surfing technique has been proposed for differential on-chip wave-pipelined serial interconnects with uniform repeaters (UR) and non-uniform repeaters to increase the data transfer rate for unidirectional schemes. In this paper, a novel bidirectional data transfer through the differential wave-pipelined serial interconnects with surfing for UR is proposed. A new circuit called 'Bidirectional surfing inverter pair' is proposed for differential wave-pipelined serial interconnects. The method of logical effort is used for the design of surfing circuits. To evaluate the efficiency of these techniques, 40 mm metal 4 interconnects using the proposed surfing techniques are implemented along with transmitter, receiver and delay locked loop in UMC 180 nm technology and their performances are studied through post layout simulations. The proposed bidirectional differential surfing scheme has a maximum data transfer rate of 2 Gb/s and has allowable jitter of 52 ps on both directions through the same interconnects. [ABSTRACT FROM AUTHOR]

A new closed-form expression of 50% propagation delay for distributed RLC interconnects is proposed using the multivariable curve fitting method, with a maximum error of 4% with respect to SPICE results. Then accurate closed-form solutions for the optimum repeater number and size to minimize the propagation delay are further derived. The performance of single-walled carbon nanotube (SWCNT) bundle interconnects is evaluated using the proposed models in the intermediate and global levels at the 22- and 32-nm technology nodes, and compared against traditional Cu interconnects. It is shown that the performance of SWCNT bundle interconnects in propagation delay can outperform Cu interconnects, and the improvement will be enhanced with technology scaling and wire length increasing. On the other hand, the propagation delay of SWCNT bundle interconnects is super-linearly dependent on the wire length similar to Cu interconnects, indicating that the method of repeater insertion to reduce the propagation delay can also apply to SWCNT bundle interconnects. The results shown that repeater insertion can really reduce the propagation delay of SWCNT bundle interconnects effectively, and the optimum repeater number is much smaller than that of Cu interconnects. [ABSTRACT FROM AUTHOR]

To realize efficient quantum communication based on quantum repeater, we propose a secure quantum network coding scheme for controlled repeater networks, which adds a controller as a trusted party and is able to control the process of EPR-pair distribution. As the key operations of quantum repeater, local operations and quantum communication are designed to adopt quantum one-time pad to enhance the function of identity authentication instead of local operations and classical communication. Scheme analysis shows that the proposed scheme can defend against active attacks for quantum communication and realize long-distance quantum communication with minimal resource consumption. [ABSTRACT FROM AUTHOR]

Due to the accelerated evolution of application services, optical network virtualization simplifies optical-layer resource management and provides flexibility in spectrum resource allocation. However, the energy consumption is one of the great challenges in the virtual optical networks (VONs). This paper focuses on the energy efficiency problem in survivable VONs with the sliceable multi-flow transponders and the elastic regenerators. For each VON, all virtual links provide the dedicated-path protection in the flexible bandwidth optical networks. An integer linear program (ILP) and a minimum unit-energy submatrix (MinEnSub) VON mapping approach are developed to improve the energy efficiency, minimize the power consumption, and reduce the spectrum usage under different line rates. For comparison, a baseline VON mapping approach is introduced. Simulation results show that the ILP model and the proposed MinEnSub VON mapping approach can save power consumption, improve the energy efficiency, and reduce the spectrum usage compared with the baseline VON mapping approach in a 6-node network. As expected, in a 14-node network, simulation results also validate that our proposed MinEnSub VON mapping approach can achieve better performance in terms of power consumption, energy efficiency, number of frequencies, and the number of regenerators. [ABSTRACT FROM AUTHOR]

ABSTRACT A dual-band on-body antenna for in-on-on wireless body area network repeater applications is proposed. This antenna consists of a dual-patch antenna and a zeroth-order resonance (ZOR) element. The two patch antenna elements form dual resonances that cover the 2.4 GHz ISM band. In addition, a triangle cut made at the lower edge of patch Element 1 improves the impedance matching in the 2.4 GHz ISM band. The ZOR element operates in the 403 MHz MICS band. The antenna has near surface radiation in the 2.4 GHz ISM band and nearly omnidirectional radiation in the 403 MHz MICS band. To evaluate the performance of the antenna on a human body, the proposed antenna is placed on a human equivalent flat phantom. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:436-441, 2016 [ABSTRACT FROM AUTHOR]

Currently, terrestrial digital multimedia broadcasting (T-DMB) systems offer an emergency alert service called automatic emergency alert service (AEAS) in emergency alert systems. The performance of T-DMB receiver for AEAS can be enhanced using cooperative communication techniques. This paper assumes the T-DMB receiver based on a cooperative communication model. Since synchronization is crucial in the performance of cooperative communications, a novel consumer synchronizer is proposed in this paper for the T-DMB receiver based on cooperative communications. The presented synchronizer includes the identification of the selected relays, which is especially required in the best-relay selection for cooperative communications. Furthermore, a channel estimation approach is suggested in the synchronizer, which is suitable for T-DMB receivers under high frequencyselectivity. The experimental results reveal that the proposed synchronizer further enhances the performance of T-DMB receiver based on cooperative communications in emergency alert systems. [ABSTRACT FROM AUTHOR]

In this paper, we have analyzed the performance of our optimized non-zero dispersion shifted fiber with three different test fibers, namely, single mode fiber, conventional non-zero dispersion shifted fiber and dispersion shifted fiber. While comparing the performances of those fibers, our optimized non-zero dispersion shifted fiber has yielded a better quality factor of 5.24 at 2.5 Gbit/s for long haul fiber length of 120 km in the absence of amplification and dispersion compensation. In order to measure the nonlinear impairments of wavelength division multiplexing channel, the quality factor values are measured at the sample channel 193.1 THz for 150 km lengthed fiber with peak input power of 6 dBm. Due to a very large effective area of optimized non-zero dispersion shifted fiber, it delivers a better quality factor of 6.12 compared to the other test fibers. We have also carried out the analysis for higher bitrates and different modulation formats at the transmission end. More phase encoded modulations of carrier-suppressed return-to-zero-differentiated phase shift keying and carrier-suppressed return-to-zero-differential quadrature phase shift keying offered optimum performances for a distance of 120 km at 10 Gbit/s bitrate. By including optical amplifiers, we could achieve a record fiber transmission length of 4000 km at the bitrate of 2.5 Gbit/s which can help the future wavelength division multiplexing optical networks to a great extent. [ABSTRACT FROM AUTHOR]

This paper proposes a quantum network coding scheme for general repeater networks so as to support long-distance quantum communication over quantum repeater networks with complex topology. The scheme includes three core parts: graph transformation, quantum channel generation, quantum information transmission. Concretely, the degree-3 $$({{D}_{3}})$$ graph transformation scheme is introduced, the quantum channel generation schemes for the cases of one-to-many, many-to-one, and many-to-many are given, and quantum information is transmitted by means of quantum teleportation. Without limitation of preparation, entangled states with arbitrary entanglement degree can be consumed as a resource of quantum communication. Scheme analysis shows that the proposed quantum network coding scheme can realize high-rate and long-distance transmission of quantum information in general networks. [ABSTRACT FROM AUTHOR]

In this study, we examine the performance of fixed gain amplify-and-forward repeaters for visible light communication (VLC) systems. We present the wireless optical channel model for VLC with the repeater and we evaluate the bit-error-rate (BER) performance for pulse-position modulation over the multipath channel with additive white Gaussian noise. The results reveal that when a repeater is placed, both the BER and the illuminance performance can be improved at any location in a typical office space. The benefit of VLC repeaters is also discussed when the channel from the source to the destination is shadowed. It is found that when the channel is shadowed, the impact of repeaters on the communication reliability is more distinct. [ABSTRACT FROM AUTHOR]

A compact 3-D dual-channel transceiver for passive wireless sensor node design is described herein. The transceiver contains two harmonic repeaters, one to be connected to a sensor and one to provide a reference signal for remote channel calibration and node identification (ID). Each repeater consists of a diode-based frequency doubler and conjugate-matched receive and transmit meandered monopole antennas. The sensing repeater operates by receiving a 2.4-GHz signal and reradiating a modulated 4.8-GHz return signal. The reference and sensing repeaters are optimized for RF input power level ranges from -\30 to -\20 dBm with zero dc power. The diagonal of the transceiver measures 0.25 \lambda at the fundamental frequency of 2.4 GHz and its measured conversion gain (CG) is -\ 12.4 dB with a 2% 3-dB CG bandwidth at -\20-dBm input power. With this performance, the communication range using an interrogator with a 2-W effective isotropic radiated power is > \40 m in a free-space environment. To the best of the authors' knowledge, the presented transceiver is the first completely passive design with built-in passive remote channel calibration and ID capability. The performance and size of the proposed design compare well with previously published passive single-channel harmonic repeaters. [ABSTRACT FROM PUBLISHER]

Hierarchical topologies are frequently proposed for large Networks-on-Chip (NoCs). Hierarchical architectures utilize, at the upper levels, long links of the order of the die size. RC delays of long links might reach dozens of clock cycles in advanced technology nodes, if delay reduction techniques (e.g. wire sizing and repeater insertion) are not applied. Some proposals assume that long links can be adjusted to satisfy timing requirements, but lack a deep evaluation of the tradeoffs and costs. Other proposals assume that long links must be pipelined, but do not provide a comprehensive justification. In this paper we evaluate the efficiency and the system costs of wire sizing and repeater insertion as methods to reduce link delays in hierarchical NoCs. We present a unified interconnect cost function that accounts for power and wiring overheads of these methods. Then, we quantify the costs of modifying long links in typical hierarchical NoCs for different target clock frequencies and technology nodes. Although long links might undergo aggressive adjustments, we find these overall costs to be low at the system level for typical cases, taking into account that there are only a few long links in most proposed hierarchical NoC architectures. A preliminary short version of this work entitled “Design Tradeoffs of Long Links in Hierarchical Tiled Networks-on-Chip (NoCs)” was presented in the 16 th Euromicro Conference on Digital System Design (DSD), 2013. [ABSTRACT FROM AUTHOR]

Spoofing and antispoofing algorithms have become an important research topic within the GNSS discipline. The power of the GNSS signal on the earth's surface averages -160 dBw. While many GNSS receivers leave large space for signal dynamics, enough power space is left for the GNSS signals to be spoofed. The goal of spoofing is to provide the receiver with a misleading signal, fooling the receiver to use fake signals in space for positioning calculations. The receiver will produce a misleading position solution. The purpose of this paper is to analyze the vulnerability of the satellite signal in repeater's output from the viewpoint of GNSS spoofing attacks. The article discusses a new approach to GNSS spoofing, based on the application of GNSS signals repeating by potential terrorists. Practical spoofing that provides misleading navigation results at the receiver is difficult to conduct due to the signal infrastructure, and by applying trivial anti-spoofing algorithms in GPS receivers, spoofing attack can be easily detected. To detect spoofing attacks of this type we have a variety of methods. For example, the authors suggest the use of paired navigators and GNSS compasses as detectors of GNSS spoofing. [ABSTRACT FROM AUTHOR]

This review paper considers the broadband potential of underground low-voltage/broadband over power lines (LV/BPL) and medium-voltage/broadband over power lines (MV/BPL) connections when N repeaters are additively deployed between their existing transmitting and receiving ends (underground LV/BPL and MV/BPL connections with (N+1)-hop repeater system). The contribution of this paper is threefold. First, the broadband performance of a great number of underground LV/BPL and MV/BPL connections with (N+1)-hop repeater system has been studied with regard to capacity and the proposed metric of capacity outage probability (COP). The analysis and relevant simulations validate the significant capacity improvement in comparison with existing underground LV/BPL and MV/BPL systems when multiple repeaters are installed across them. Second, it is found that the underground BPL network capacity performance depends drastically on factors such as the electromagnetic interference (EMI) limits and the deployment of multiple-input multiple-output (MIMO) systems across the underground BPL connections. Adopting (N+1)-hop repeater systems, capacity losses due to: (i) existing strict EMI limits; and (ii) avoidance of MIMO/LV/BPL and MIMO/MV/BPL systems deployment; can be reduced. Third, the numerical simulations reveal the importance of considering as a suitable countermeasure technique against potential capacity discrepancies the installation of (N+1)-hop repeater system across the existing underground BPL connections. This capacity mitigation technique can significantly improve the capacity performance of existing LV/BPL and MV/BPL installations when strict EMI limits or disregard of MIMO system installations inhibit imminent BPL network expansion. [ABSTRACT FROM AUTHOR]

A dual-channel subwavelength low-power radio repeater system is presented in this communication. The repeater system is composed of a low-profile miniaturized receive antenna, an end-fire two-element miniaturized transmit antenna array, and a low-power high-gain amplifier chain. The isolation between the receive antenna and transmit antenna is achieved by a near-field cancellation method. To achieve a dual-channel response antennas are made wideband using parasitic elements and the open-loop transfer function is designed in a manner to present zero-crossing phase at two frequency points within the band. The closed-loop gain of the repeater system has a gain higher than that of the amplifier at the zero-crossing phase frequency points, which gives rise to repeater performance at two distinct channels. A prototype of the repeater system operating in 2.4 \sim 2.5~GHz with dimensions of 39.67~mm \times 85.39~mm \times 3.18~mm is designed and fabricated. Performance of this repeater is characterized experimentally by measuring its radar cross section (RCS). Using an amplifier chain with gain of 45 dB, it is shown that dual-channel repeater exhibits RCS values of 27.7 dBsm and 26.0 dBsm at 2.42 GHz and 2.44 GHz, respectively. [ABSTRACT FROM PUBLISHER]

This paper presents an analysis of magnetic resonance coupling effects that can be considered for realizing a wireless power transfer (WPT) system. In this study, numerical analysis is applied to investigate the power transfer characteristics affected by coil inductance and placement. The simulations and experiments, using various coils and positions, are conducted to find the optimum power transfer condition. The experiment shows that the frequency bandwidth of the wireless power transfer at the optimum coupling condition is enlarged to 0.73 MHz and the transfer efficiency is maintained at over 80%. [ABSTRACT FROM PUBLISHER]

Multiple repeat false targets (RFTs), created by the digital radio frequency memory (DRFM) system of jammer, are widely used in practical to effectively exhaust the limited tracking and discrimination resource of defence radar. In this paper, common characteristic of radar polarization echoes of multiple RFTs is used for target recognition. Based on the echoes from two receiving polarization channels, the instantaneous polarization radio (IPR) is defined and its variance is derived by employing Taylor series expansion. A detection-discrimination method is designed based on probability grids. By using the data from microwave anechoic chamber, the detection threshold of the method is confirmed. Theoretical analysis and simulations indicate that the method is valid and feasible. Furthermore, the estimation performance of IPRs of RFTs due to the influence of signal noise ratio (SNR) is also covered. [ABSTRACT FROM AUTHOR]

The study of magnetars is of particular relevance since these objects are the only laboratories where the physics in ultra-strong magnetic fields can be directly tested. Until now, spectroscopic and timing measurements at X-ray energies in soft gamma repeaters and anomalous X-ray pulsars (AXPs) have been the main source of information about the physical properties of a magnetar and of its magnetosphere. Spectral fitting in the ∼0.5–10 keV range allowed us to validate the ‘twisted magnetosphere’ model, probing the structure of the external field and estimating the density and velocity of the magnetospheric currents. Spectroscopy alone, however, may fail in disambiguating the two key parameters governing magnetospheric scattering (the charge velocity and the twist angle) and is quite insensitive to the source geometry. X-ray polarimetry, on the other hand, can provide a quantum leap in the field by adding two extra observables, the linear polarization degree and the polarization angle. Using the bright AXP 1RXS J170849.0−400910 as a template, we show that phase-resolved polarimetric measurements can unambiguously determine the model parameters, even with a small X-ray polarimetry mission carrying modern photoelectric detectors and existing X-ray optics. We also show that polarimetric measurements can pinpoint vacuum polarization effects and thus provide indirect evidence for ultra-strong magnetic fields. [ABSTRACT FROM AUTHOR]

This paper proposes novel high isolation transmitter and receiver antennas that make use of high-impedance surfaces (HISs) for repeater applications. Both the microstrip antennas and HISs are designed to operate at a frequency of 2.05 GHz for Korean WCDMA services. The HIS proposed in this paper can effectively absorb back radiation and surface waves from each antenna, and this reduces coupling between the two antennas. Therefore, it is experimentally demonstrated that the use of HISs improves isolation by 6 and 10 dB, depending on the orientation of the two antennas. [ABSTRACT FROM PUBLISHER]

Stability and output signal quality are always two major concerns with the deployment of on-channel repeaters. This paper proposes a gain management scheme and evaluates the performance of the proposed gain management technique for on-channel repeaters. The gain manager uses a loop gain metric as an indication of stability and output signal quality (SNR) of the repeater to continuously and accurately monitor the repeater status, and adjust the repeater gain accordingly. The repeater output SNR and stability can thus be tightly controlled. It is demonstrated that the proposed gain management ensures the safe and robust operation of the repeater against the dynamics of the environment. [ABSTRACT FROM PUBLISHER]

This paper considers an issue of signal coverage in uncovered places using a broadcasting device called a Gap Filler. The main focus is placed on the analysis of potential negative effects while signals from two and more primary transmitters simultaneously enter to the Gap Filler. In particular, in the measurements the impact of reception cross delayed signals received by the Gap Filler from two adjacent primary transmitters operating in the Single Frequency Network was analysed. The influence of different receive signal levels from two adjacent primary transmitters was also examined. In the conclusion, based on the experiments, the limiting factors useful for individual transmitters in the Single Frequency Network were determined. The analysis and finding the limit parameters can help broadcasters in further setting and debugging of the Gap Filler network. Finally, the described laboratory experiment was also verified under the real SFN network condition in border region Vsetinsko to verify the laboratory findings. [ABSTRACT FROM AUTHOR]

Network-on-chips (NoCs) have emerged as a scalable solution to the wire delay constraints, thereby providing a high-performance communication fabric for future multicores. Research has shown that power, area, and performance of the NoC architecture are tightly integrated with the design and optimization of the link, router (buffer and crossbar), and topology. Recent work has shown that adaptive channel buffers (on-link storage) can considerably reduce power consumption and area overhead by reducing or replacing the power-hungry router buffers. However, channel buffer design can lead to head-of-line (HoL) blocking, which eventually reduces the throughput of the network. In this paper, we design channel buffers and router crossbars to improve the performance (latency, throughput) while reducing the power consumption. In addition, we implement the proposed channel buffers and crossbar organizations in a concentrated torus (CTorus) topology which is a dual network without the additional area overhead. We compare other dual networks with leading topologies such as mesh2X, concentrated mesh2X (CMesh2X), and flattened butterfly2X (FBfly2X), each implemented with channel buffers. Our proposed designs analyze the power–performance–area tradeoff in designing channel buffers for NoC architectures while alleviating HoL blocking through buffer organizations and crossbar optimizations. Results using Synopsys design compiler showed that the buffer and crossbar organizations for an 8\,\times\,8 mesh architecture can reduce power consumption by 25%–40%, improve throughput and reduce latency by 525%, while occupying 4%–13% more area when compared to the baseline architecture for both synthetic as well as real benchmark traces such as Princeton Application Repository for Shared-Memory Computers (PARSEC) and Standard Performance Evaluation Corporation (SPEC). CPU2006. When the energy-efficient buffer and crossbar organization was inserted into our CTorus topology, we further reduced energy dissipation by 32% and area by 53%, on average, over mesh2X, CMesh2X, and FBfly2X. [ABSTRACT FROM AUTHOR]

In this article, the author focuses on the Broadband over Power line (BPL) and the use of smart grids for the BPL. He informs that the BPL is a method of power line communication, which allows high-speed digital data transmission over the public electric distribution wiring, and International Broadband Electric Communications Inc. has ceased the trading of BPL operations in the U.S. in 2012. He mentions that electric firms can increase BPL access by inserting repeaters at regular intervals. INSET: CAN SMART GRIDS BENEFIT FROM LESSONS LEARNED?.

In heterogeneous dense networks where spectrum is shared, users' privacy remains one of the major challenges. On a multi-antenna relay-assisted multi-carrier interference channel, each user shares the spectral and spatial resources with all other users. When the receivers are not only interested in their own signals but also in eavesdropping other users' signals, the cross talk on the spectral and spatial channels becomes information leakage. In this paper, we propose a novel secrecy rate enhancing relay strategy that utilizes both spectral and spatial resources, termed as information leakage neutralization. To this end, the relay matrix is chosen such that the effective channel from the transmitter to the colluding eavesdropper is equal to the negative of the effective channel over the relay to the colluding eavesdropper and thus the information leakage to zero. Interestingly, the optimal relay matrix in general is not block-diagonal which encourages users' encoding over the frequency channels. We proposed two information leakage neutralization strategies, namely efficient information leakage neutralization (EFFIN) and local-optimized information leakage neutralization (LOPTIN). EFFIN provides a simple and efficient design of relay processing matrix and precoding matrices at the transmitters in the scenario of limited power and computational resources. LOPTIN, despite its higher complexity, provides a better sum secrecy rate performance by optimizing the relay processing matrix and the precoding matrices jointly. The proposed methods are shown to improve the sum secrecy rates over several state-of-the-art baseline methods. [ABSTRACT FROM AUTHOR]

In this paper, we propose two-hop user-deployable indoor relays for CDMA systems with signal bandwidth 5 MHz or less. We assume concurrent relaying wherein macro base stations (BS) are allowed to transmit when a relay is forwarding. The two-hop indoor relay is studied using a generalized model for outdoor-to-indoor communication in a frequency-selective channel in the presence of co-channel interference. We propose an equalize-and-forward relay that employs multiple-antenna interference-aware equalization before forwarding. We present a unified solution to minimize interference (due to concurrent transmissions) at the relay-served destination and the BS-served destination, using power control and exploiting spatial reuse. A systematic method to enable indoor relays with the proposed interference management solutions is presented that is applicable to existing CDMA systems, without additional requirements in Access Terminal (AT)/User Equipment. Simulation results in the context of High Rate Packet Data (HRPD) CDMA network shows that the ATs served through the indoor relays experience throughput improvement by at least a factor of two, whereas the ATs served by the BS experienced a gain of around 6% in spite of concurrent relaying. The results also show an overall system throughput gain upto 30% when compared to the existing network with only single hops. [ABSTRACT FROM PUBLISHER]

The demand for wireless power transfer via magnetic resonance coupling is increasing. Magnetic resonance coupling is a new technology that achieves power transfers across a large air gap by using transmitting and receiving antennas. However, repeater antennas can enable power transmission across an even larger distance. These repeater antennas without cross coupling can be expressed as a T-type equivalent circuit. Equivalent circuits that include cross coupling and mutual inductance, which is related to the antenna position, have not been studied. In this paper, a novel way to represent a repeater antenna by an equivalent circuit and a way to determine the mutual inductance are proposed and verified by performing an electromagnetic field analysis and experiment. [ABSTRACT FROM AUTHOR]

Crosstalk between interconnects is simulated by SPICE and the results are analyzed. The analysis shows that crosstalk between interconnects can be controlled by repeater insertion and proper sizing of the repeaters. For the best control of crosstalk smallest size repeaters with a number of repeaters is suggested. The dependence of cross-talk on signal transition time and interconnect length are examined and verified with previously reported results. Distributed RLC transmission line model of interconnect is considered. [ABSTRACT FROM AUTHOR]

During systems-on-a-chip (SoC) integration, silicon intellectual properties (IPs) are generally regarded as blockages to long interconnections that connect different IPs. With this constraint, conventional designs are forced to place those repeaters that drive long interconnections outside the IP. These designs either lead to a longer interconnection distance requiring more repeaters or result in a longer signal delay, since the interconnection wire is not appropriately segmented by the repeaters. To solve these problems, we designed the IPs such that designers can embed the repeaters in the IP for the SoC integration. In other words, it allows the cross-IP interconnections to be routed over the IP using repeaters inserted in the IP. The design concept, physical implementation, and application examples of the embedded repeaters are described in this brief. Experimental results show that the proposed design will not only make the floor plan of the SoC easier but will also improve the signal delay and the power consumption of the long interconnection circuits. [ABSTRACT FROM PUBLISHER]

The main design issues and performance characterization of an echo canceller for digital on-channel repeaters (OCRs) applicable to multiple standards for communications and broadcasting are addressed. In particular, in this paper we focus on a DVB-T/H scenario. The low-complexity channel cancellation technique here described is based on the introduction of a negative feedback loop capable to counterbalance the coupling effects between the OCR antennas (echoes). In the initial phase, locally generated pulse trains are transmitted to estimate the coupling channel between the transmitting and the receiving antennas. This first echo estimation is used to set-up the canceling unit, whose purpose is to generate a properly filtered replica of the repeated DVB-T/H signal compensating the echoes. After the initial set-up of the system, efficient tracking of the echoes can be performed through conventional least mean square (LMS) techniques. After developing a proper theoretical model, we introduce and discuss some important performance figures such as mean rejection ratio (MRR) and echo suppression at nominal position (ESNP). Then, a detailed description of our implementation of the echo canceller on a field programmable gate array (FPGA) board is reported. Finally, the performance of our prototype is evaluated and the measurement results are compared with those derived by the analytical model. [ABSTRACT FROM AUTHOR]

This paper extends the existing transmission and capacity analysis in order to investigate the broadband potential of overhead high-voltage/broadband over power lines (HV/BPL) connections where a single repeater is additively deployed between their existing transmitting and receiving ends (overhead HV/BPL connections with two-hop repeater system). The contribution of this paper is threefold. First, the broadband performance of various overhead HV/BPL connections with two-hop repeater system has been studied with regard to their cumulative capacity. The analysis and relevant simulations validate the potentially excellent communications medium of overhead HV/BPL channels over a 25 km repeater span well beyond 88 MHz in terms of cumulative capacity. In addition, through the deployment of two-hop repeater systems, apart from the upsurge of cumulative capacity, overhead HV/BPL connections become more adaptive to different capacity requirements. Second, it is found that overhead HV/BPL network capacity performance depends drastically on factors such as the overhead HV grid topology and the noise characteristics. Through the deployment of two-hop repeater systems, capacity losses due to existing aggravated overhead HV/BPL topologies and high noise environments are significantly reduced. Third, the numerical results reveal the importance of considering as suitable mitigation technique the deployment of overhead HV/BPL connections with two-hop repeater system. Except for the low-cost and quick technology upgrade of existing overhead HV/BPL networks, this mitigation technique may permit the future broadband exploitation of overhead HV/BPL networks and their interoperability with other broadband technologies. [ABSTRACT FROM AUTHOR]

This article brings in the second part general information about half-wave impedance repeater. The third part describes the basic functional principles of the half-wave impedance repeater using Smith chart. The main attention is focused in part four on the derivation of repeater frequency bandwidth depending on characteristics and load impedance of unknown feeder line. Derived dependences are based on the elementary features of the feeder lines with specific length. The described functionality is proved in part 4.3 by measurement of transformed impedance using vector several unbalanced feeder lines and network analyzer VNWA3+. [ABSTRACT FROM AUTHOR]

In this paper I presented the role of filters duplex in structure of voice repetors, operating principles specific subassembly transmission and subassembly reception. I wanted to do a filter, for building a repeater duplexer for band 144Mhz - 146Mhz. I described how to make a cavity. Leaving the wiring diagram and I checked, depending on the size, if designed cavity can be used for VHF frequencies corresponding. I examined the response of this filter, for receiving and transmitting frequencies, specific to repetor that will be made [ABSTRACT FROM AUTHOR]