Ground antennas are suitable for use in mobile electronic devices due to their compactness. These ground antennas incorporate two capacitors for controlling the resonance frequency and a shorting loop for impedance matching. In this work, we compare the performance of a ground antenna with that of a meandered inverted-F antenna (IFA). It is numerically and experimentally shown that a ground antenna can yield simultaneous improvements in both the antenna size and radiation efficiency when compared to the meandered IFA. The bandwidth of the ground antenna for a voltage standing wave ratio (VSWR) of 3:1 is 240 MHz from 2350 MHz to 2590 MHz, while the minimum total antenna efficiency is 62% within the 2.4 GHz ISM band.

Orthogonal Frequency Division Multiple Access (OFD-MA) is a leading air interface candidate for future generation cellular networks. However, if deployed in a multi-user multi-tier cellular system, it is important to fairly share radio resources such as transmission power and sub-carriers among co-tier and cross-tier users. This paper focuses on a mathematical formulation of cell inner-zone/outer-zone radio resource partitioning variables and considers the case of an FFR-based macrocell underlaid with femtocell. By applying an exhaustive search procedure on the developed formulation, we determine the optimal radio resource partitioning parameter values from the perspectives of macrocell user fairness and femtocell throughput maximization.

We propose a deception mechanism to combat a compromised station in IEEE 802.11 channel hopping systems. A compromised station can follow the hopping channels and continuously attack them, since it recognizes the channel-hopping sequence. The key concept of the deception mechanism is that an access point notifies a new hopping seed but not to the jammer, while a deception station deceives the jammer. Simulations show that the proposed scheme increases network throughput compared to conventional channel hopping schemes when they are under compromised station attacks.

An on-chip soft-start circuit based on a switched-capacitor for DC-DC switching regulator is presented. A ramp-voltage, which is generated by a switched-capacitor, is used to make pulse width slowly increase from zero, in order to eliminate the inrush current and the overshoot voltage during start-up. The post simulation results show that the regulator soft starts well with the proposed soft-start circuit.

In this paper, two efficient redeployment strategies which are designed to balance the detection coverage rate and maintenance period are proposed. To develop these strategies, we first analyze the sensor detection coverage and energy consumption model. We then propose a network maintenance indicator that considers the coverage rate and residual energy in each node. We adopt the network maintenance indicator as the cost function. That is, the network maintenance is formulated as a cost optimization problem. Finally we propose COST_MAX_MIN and COST_MAX_AVG strategies to select the redeployed location of candidate nodes. Simulation results show that the COST_MAX_AVG prolong the repair period in comparison with the COST_MAX_MIN strategy.

The left-handed (LH) operation of a three-dimensional (3-D) LH material composed of wired metallic spheres is experimentally confirmed. A 15153-cell periodic structure designed to have an isotropic LH characteristics is fabricated by a 3-D printer with post plating technology, and near-field measurements of refracted waves by the negative refractive index slab lens are carried out. The dispersion characteristics measured from the near-field distributions on the surface of the LH material clearly show that the structure supports the backward waves at 12 GHz band. It is also shown experimentally that the resolution of the slab lens exceeds the diffraction limit by near field measurements with a single source and adjacent two sources. In addition, near-field measurements from the LH material near the Γ-point frequency at 12.90 GHz are carried out. A highly directive plane wave with a single point source is observed and the near-zero-index operation has been confirmed.

As business values pursued by today's organizations are abstract concepts, measurement of these values and their achievement is not straightforward. This paper proposes a value achievement measuring and managing framework, which recursively decomposes business values to construct a value hierarchy and then links it with the business process hierarchy. The framework makes it possible to measure value achievement, trace values to processes, and take necessary actions in response to the measured progress in value achievement.

Reinforcement learning (RL) is a flexible framework for learning a decision rule in an unknown environment. However, a large number of samples are often required for finding a useful decision rule. To mitigate this problem, the concept of transfer learning has been employed to utilize knowledge obtained from similar RL tasks. However, most approaches developed so far are useful only in low-dimensional settings. In this paper, we propose a novel transfer learning idea that targets problems with high-dimensional states. Our idea is to transfer knowledge between state factors (e.g., interacting objects) within a single RL task. This allows the agent to learn the system dynamics of the target RL task with fewer data samples. The effectiveness of the proposed method is demonstrated through experiments.

A 60 GHz direct conversion transceiver which employs amplitude/phase imbalance cancellation technique is newly proposed. By using the proposed technique, the receive path of the transceiver achieves less than 0.2 dB of amplitude error and less than 3 of phase error at 60 GHz bands over a 10 GHz bandwidth, which relaxes the design accuracy required for baluns used in the transceiver. It also employs a simple and fast calibration algorithm to adjust the locking range of the divide-by-3 injection locked divider in the phase locked loop. Fabricated in 90 nm CMOS technology, the transceiver achieves a low power consumption of 230 mW in transmit mode and 173 mW in receive mode. The output spectrum of 1.76 Gsps π/2-BPSK/QPSK modulation shows the excellent distortion and spurious suppression that meet the IEEE802.11ad draft standard.

This paper proposes non-coherent multiple-input multi-ple-output (MIMO) communication systems employing per transmit antenna differential mapping (PADM), which generates an independent differentially encoded sequence for each of the multiple transmit antennas by means of space-time coding and mapping. At a receiver, the proposed PADM employs adaptive maximum-likelihood detection (MLD). The features of PADM are as follows: 1) it has excellent tracking performance for fast time-varying fading channels, because it can detect transmitted data without needing channel state information (CSI); 2) it can be applied not only to transmit diversity (TD) but also to spatial multiplexing (SM). In this paper, we analyze the adaptive MLD based on pseudo matrix inversion and derive its metric for data detection. In order to satisfy requirements on multiple transmitted sequences for the adaptive MLD, this paper proposes a mapping rule for PADM. Next, this paper describes a receiver structure based on per-survivor processing (PSP), which can drastically reduce the complexity of adaptive MLD. Finally, computer simulations confirm that the proposed non-coherent MIMO communication systems employing PADM have excellent tracking capability for TD and SM on fast time-varying fading channels.

Ground truth based image segmentation evaluation paradigm plays an important role in objective evaluation of segmentation algorithms. So far, many evaluation methods in terms of comparing clusterings in machine learning field have been developed. However, most traditional pairwise similarity measures, which only compare a machine generated clustering to a “true” clustering, have their limitations in some cases, e.g. when multiple ground truths are available for the same image. In this letter, we propose utilizing an information theoretic measure, named NJMI (Normalized Joint Mutual Information), to handle the situations which the pairwise measures can not deal with. We illustrate the effectiveness of NJMI for both unsupervised and supervised segmentation evaluation.

We report the first successful experiment on Point-to-Multipoint (P2MP) VLAN path establishment on the overlay-model-based GMPLS-controlled wide area Ethernet. To support the overlay model, P2MP VLAN path signaling with egress output port indication is proposed and implemented. It is confirmed that our extended RSVP-TE software can correctly establish P2MP VLAN paths in the overlay-model network.

For an adaptive system identification filter with a stochastic input signal, a coefficient vector updated with an NLMS algorithm converges in the sense of ensemble average and the expected convergence vector has been revealed. When the input signal is periodic, the convergence of the adaptive filter coefficients has also been proved. However, its convergence vector has not been revealed. In this paper, we derive the convergence vector of adaptive filter coefficients updated with the NLMS algorithm in system identification for deterministic sinusoidal inputs. Firstly, we derive the convergence vector when a disturbance does not exist. We show that the derived convergence vector depends only on the initial vector and the sinusoidal frequencies, and it is independent of the step-size for adaptation, sinusoidal amplitudes, and phases. Next, we derive the expected convergence vector when the disturbance exists. Simulation results support the validity of the derived convergence vectors.

The need for the OpenGL-family of the 3D rendering API's are highly increasing, especially for graphical human-machine interfaces on various systems. In the case of safety-critical market for avionics, military, medical and automotive applications, OpenGL SC, the safety critical profile of the OpenGL standard plays the major role for graphical interfaces. In this paper, we present an efficient way of implementing OpenGL SC 3D graphics API for the environments with hardware-supported OpenGL 1.1 and its multi-texture extension facility, which is widely available on recent embedded systems. Our approach achieved the OpenGL SC features at the low development cost on the embedded systems and also on general personal computers. Our final result shows its compliance with the OpenGL SC standard specification. From the efficiency point of view, we measured its execution times for various application programs, to show a remarkable speed-up.

Establishing peer-to-peer (P2P) live streaming for mobile ad hoc network (MANET) requires an efficient scheme to deliver the real-time data in the infrastructure-less disaster environment. However, P2P membership management is difficult in the dynamic mobility and resource limited MANET. In this paper, we present a cross-layer design for P2P-MANET which integrates P2P DHT-based routing protocol and IPv6 routing protocol. Therefore, the proposed scheme can manage and recover the P2P overlay as well as selecting efficient routing path to multicast video streaming. The simulation results demonstrate that the proposed scheme performs relatively better than the layered approach or the off-the-shelf design in terms of the playback continuity and signaling overhead.

Compressing a JPEG image twice will greatly decrease the values of some of its DCT coefficients. This effect can be easily detected by statistics methods. To defend this forensic method, we establish a model to evaluate the security and image quality influenced by the re-compression. Base on the model, an optimized adjustment of the DCT coefficients is achieved by Genetic Algorithm. Results show that the traces of double compression are removed while preserving image quality.

This letter proposes a new model of state machine called Finite Virtual State Machine (FVSM). A memory-based architecture and a procedure for generating FVSM implementations from Finite State Machines (FSMs) are presented. FVSM implementations provide advantages in speed over conventional RAM-based FSM implementations. The results of experiments prove the feasibility of this approach.

Single front-end architecture with parasitic antenna element (PAE) in compact array system has been proposed for enhancing spectral efficiency and miniaturizing the receiver. Although most of studies paid attention to design optimal receiver with antenna mutual coupling on fading correlation, relatively little attention has been paid to noise. In this paper, we propose a low noise model for single front-end MIMO receiver system with PAE which includes arbitrary signal and noise coupling. The proposed model articulates physical noise sources and relates their spatial correlation with array receive antennas, parasitic element, front-end and matching circuit. A matching circuit is designed to achieve minimum noise figure. After that, the optimal PAE value is derived to maximize channel capacity. We present numerical analysis to verify the proposed system on certain conditions.

This paper proposes an easy-to-design, theory-consistent compact feeding circuit, with a single input and four outputs, being comprised of two hybrid circuits that are capable of switching a beam in three directions. The circuits that determine the phase differences between the antennas are present on the same single layer, and thus there is no effect of vias and the design agrees well with the underlying theory. In addition, the vertically and horizontally symmetrical circuit pattern contributes to a substantial reduction in design time. The circuit is designed for use in the ISM band and its properties are evaluated using an RF circuit simulator. A prototype is fabricated and evaluated. The results of the simulation and measurement agree well with the theoretical values. The dimensions of the feeding circuit are 75 (H)55 (W)3.0 (T) mm.

Prefix caching improves the performance of IP lookup by exploiting spatial and temporal locality of IP references. However, it cannot cache non-leaf prefixes, so several prefix expansion schemes have been proposed to handle those prefixes. Such schemes have some drawbacks to incur modification of routing table or severe miss penalty. We propose an efficient prefix expansion scheme which achieves good performance without additional burden to lookup scheme. In the proposed scheme a non-leaf prefix is expanded to the length of the longest immediate descendant prefix when it is cached. Evaluation result shows our scheme achieves very low miss ratio even though it does not increase the size of routing table and cache miss penalty.