The Voronoi game is a two-person perfect information game modeling a competitive facility location. The original version of the game is played on a continuous domain. Only two special cases (1-dimensional case and 1-round case) have been extensively investigated. Recently, the discrete Voronoi game of which the game arena is given as a graph was introduced. In this note, we give a complete analysis of the discrete Voronoi game on a path. There are drawing strategies for both the first and the second players, except for some trivial cases.

Broadcasters transmit TV programs and often need to transmit an individual message, e.g. an individual contract, to each user. The programs have to be encrypted in order to protect the copyright and the individual messages have to be encrypted to preserve the privacy of users. For these purposes, broadcasters transmit not only encrypted content but also encrypted personalized messages to individual users. Current broadcasting services employ an inefficient encryption scheme based on a symmetric key. Recently, several broadcast encryption schemes using a public key have been proposed in which the broadcaster encrypts a message for some subset S of users with a public key and any user in S can decrypt the broadcast with his/her private key. However, it is difficult to encrypt a personalized message and transmit it to every user efficiently. In this paper, we propose a broadcast encryption scheme that has a personalized message encryption function. We show that our scheme is efficient in terms of the ciphertext size.

Motivated by the question of how to quickly transfer large files if multiple and heterogeneous networks are available but each has insufficient performance for a requested task, we propose a data transfer framework for integrating multiple and heterogeneous challenged access networks, in which long delays, heavy packet losses, and frequent disconnections are observed. An important feature of this framework is to transmit the control information separately from the transmission of data information, where they are flexibly transferred on different types of communication media (network paths) in different ways, and to provide a virtual single network path between the two nodes. We describe the design of the mechanisms of this framework such as the retransmission, the rate adjustment of each data flow, and the data-flow setup control. We validate a prototype implementation through two different experiments using terrestrial networks and a satellite communication system.

This letter is devoted to derivation of a transformation law which converts a class of nonlinear affine control systems with n-states and 2-iputs into simpler systems with chained structure. First, we give a problem formulation that we consider throughout this letter. We next introduce a transformation law and gives its mathematical certification. Then, we apply the transformation method to an example and consider control design based on chained structure for the example in order to confirm the effectiveness of our approach.

We propose a statistical method for counting pedestrians. Previous pedestrian counting methods are not applicable to highly crowded areas because they rely on the detection and tracking of individuals. The performance of detection-and-tracking methods are easily degraded for highly crowded scene in terms of both accuracy and computation time. The proposed method employs feature-based regression in the spatiotemporal domain to count pedestrians. The proposed method is accurate and requires less computation time, even for large crowds, because it does not include the detection and tracking of objects. Our test results from four hours of video sequence obtained from a highly crowded shopping mall, reveal that the proposed method is able to measure human traffic with an accuracy of 97.2% and requires only 14 ms per frame.

This paper introduces a hard handover strategy with a novel adaptive hysteresis adjustment that is needed to reduce handover drop rate in 3GPP long term evolution (LTE). First of all, we adopt a Hybrid handover scheme considering both the received signal strength (RSS) and the load information of the adjacent evolved Node Bs (eNBs) as a factor for deciding the target eNB. The Hybrid scheme causes the load status between the adjacent eNBs to be largely similar. Then, we propose a modified load-based adaptive hysteresis scheme to find a suitable handover hysteresis value utilizing the feature of the small load difference between the target and serving eNBs obtained from the result of the Hybrid scheme. As a result, through the proposed modified load-based adaptive hysteresis scheme, the best target cell is very well selected according to the dynamically changing communication environments. The simulation results show that the proposed scheme provides good performance in terms of handover drop rate.

Admission control is a procedure to guarantee a given level of Quality of Service (QoS) by accepting or rejecting arrival connection requests. There are many studies on backlog or loss rate evaluation formulas for admission control at a single node. However, there are few studies on end-to-end evaluation formulas suitable for admission control. In a previous paper, the authors proposed a new stochastic network calculus for many flows using an approach taken from large deviations techniques and obtained asymptotic end-to-end evaluation formulas for output burstiness and backlog. In this paper, we apply this stochastic network calculus to a heterogeneous tandem network with many forwarding flows and cross traffic flows constrained by leaky buckets, and obtain a simple evaluation formula for the end-to-end backlog. In this formula, the end-to-end backlog can be evaluated by the traffic load at the bottle neck node. This result leads us to a natural extension of the evaluation formula for a single node.

In the present paper, we propose an object tracking method called scenario-type hypothesis object tracking. In the proposed method, an indoor monitoring region is divided into multiple closed micro-cells using sensor nodes that can detect objects and their moving directions. Sensor information is accumulated in a tracking server through wireless multihop networks, and object tracking is performed at the tracking server. In order to estimate the trajectory of objects from sensor information, we introduce a novel concept of the virtual world, which consists of virtual micro-cells and virtual objects. Virtual objects are generated, transferred, and deleted in virtual micro-cells according to sensor information. In order to handle specific movements of objects in micro-cells, such as slowdown of passing objects in a narrow passageway, we also consider the generation of virtual objects according to interactions among virtual objects. In addition, virtual objects are generated when the tracking server estimates loss of sensor information in order to decrease the number of object tracking failures. Through simulations, we confirm that the ratio of successful tracking is improved by up to 29% by considering interactions among virtual objects. Furthermore, the tracking performance is improved up to 6% by considering loss of sensor information.

We report on the fabrication of coplanar dual-gate ZnO thin-film transistors with 200-nm thickness SiNx for both top and bottom dielectrics. The ZnO film was deposited by RF magnetron sputtering on SiO2/Si substrates at 100. And the thickness of ZnO film is compared with 100-nm and 40-nm. This TFT has a channel width of 100-µm and channel length of 5-µm. The fabricated coplanar dual-gate ZnO TFTs of 40-nm-thickness exhibits a field effect mobility of about 0.29 cm2/V s, a subthreshold swing 420 mV/decade, an on-off ratio 2.7107, and a threshold voltage 0.9 V, which are greatly improved characteristics, compared with conventional bottom-gate ZnO TFTs.

We propose optimal power allocation schemes for a secondary cognitive user sharing spectrum with a primary user under different interference power constraints in Rayleigh fading channels. Specifically, we consider a practical scenario in which the secondary user has a fixed transmission rate and the instantaneous channel state of the interference channel is not available to the secondary user. Simulation results verify the feasibility of the proposed schemes and evaluate the effective transmission rate loss due to the incomplete channel state information.

Wireless body area network for sensing and monitoring of vital signs is the one of most rapidly growing wireless communication system and Ultra Wide-Band (UWB) is a favorable technology for wearable medical sensors. The wireless body area networks promise to revolutionize health monitoring. However, designers of such systems face a number of challenging tasks. Efficient transceiver design requires in-depth understanding of the propagation media which in this case is the human body surface. The human body is not an ideal medium for RF wave transmission; it is partially conductive and consists of materials of different dielectric constants, thickness and characteristic impedance. The results of the few measurement experiments in recent publications point to varying conclusions in the derived parameters of the channel model. As obtaining large amount of data for many scenarios and use-cases is difficult for this channel, a detailed simulation platform can be extremely beneficial in highlighting the propagation behavior of the body surface and determining the best scenarios for limited physical measurements. In this paper, an immersive visualization environment is presented, which is used as a scientific instrument that gives us the ability to observe three-dimensional RF propagation from wearable medical sensors around a human body. We have used this virtual environment to further study UWB channels over the surface of a human body. Parameters of a simple statistical path-loss model and their sensitivity to frequency and the location of the sensors on the body are discussed.

We present a review of several types of microwave antennas made of metamaterials, including the resonant electrically small antennas, metamaterial-substrate patch antennas, metamaterial flat-lens antennas, and Luneburg lens antennas. In particular, we propose a new type of conformal antennas using anisotropic zero-index metamaterials, which have high gains and low sidelobes. Numerical simulations and experimental results show that metamaterials have unique properties to design new antennas with high performance.

Gate delay evaluation is always a vital concern for high-performance digital VLSI designs. As the feature size of VLSIs decreases to the nano-meter region, the work to obtain an accurate gate delay value becomes more difficult and time consuming than ever. The conventional methods usually use iterative algorithms to ensure the accuracy of the effective capacitance Ceff, which is usually used to compute the gate delay with interconnect loads and to capture the output signal shape of the real gate response. Accordingly, the efficiency is sacrificed. In this paper, an accurate and efficient approach is proposed for gate delay estimation. With the linear relationship of gate output time points and Ceff, a polynomial approximation is used to make the nonlinear effective capacitance equation be solved without iterative method. Compared to the conventional methods, the proposed method improves the efficiency of gate delay calculation. Meanwhile, experimental results show that the proposed method is in good agreement with SPICE results and the average error is 2.8%.

The high-speed downlink packet access (HSPDA) system is expected to effectively support voice services when Release 7/8 features are adopted in the system. In this letter, we point out that a voice packet can be transmitted at a lower power level than normal in the HSDPA network. We propose a power allocation scheme that adjusts the transmission power of voice packets optimally and allocates the remaining transmission power to data services in order to improve data throughput. The proposed power allocation is analyzed with a Rayleigh fading channel model and compared to conventional fixed power allocation.

Owing to the concerns about electromagnetic interference (EMI) from wireless local area networks (WLAN), an investigation into its impact on medical equipment is carried out. The results indicate that there is no evidence of 802.11 Wireless LAN systems being unsafe for installation inside hospital premises and only one piece of equipment was found to be susceptible to IEEE 802.11b standard.

In this paper, we propose a new interference alignment (IA) scheme that jointly designs the linear transmitter and receiver for the 2-user MIMO X channel system, using minimum total mean square error criterion, subject to each transmitter power constraint. We show that transmitters and receivers under such criteria could be realized through a joint iterative algorithm. Considering the imperfection of channel state information (CSI), we also extend the minimum mean square error interference alignment schemes for the MIMO X channel with CSI estimation error. A robust iterative algorithm which is insensitve to CSI estimation error is proposed. Simulation results are also provided to demonstrate the proposed algorithm.

CMOS SoCs can reduce power consumption while maintaining performance by adopting voltage scaling (VS) technologies. The operating speed of the level converter (LC) strongly affects the effectiveness of VS technologies. However, PVT variations can cause serious problems to the LC, because the state-of-the-art LC designs do not give enough attention to this issue. In this work, we proposed to analyze the impact of PVT variations on the performance of the LC using a previously developed heuristic sizing methodology. Based on the evaluation results from different operating corners with different offset voltages and temperatures, we proposed a variation-tolerant LC that achieves both high performance and low energy with a high tolerability for PVT variations.

We fabricated metal-oxide-semiconductor (MOS) devices with Pt/Ta2O5 gate stacks and investigated their electrical and structural properties. As increasing RF magnetron sputter-deposition time of Ta2O5 film, the values of equivalent oxide thickness (EOT) and flat band voltage (VFB) increase whilst the density of interfacial trap (Dit) gradually decreases. The effective metal work function (Φm,eff) of Pt metal gate, extracted from the relations of EOT versus VFB are calculated to be ∼5.29 eV, implying that Fermi-level pinning in Ta2O5 gate dielectric is insignificant.

We analyze linear channel estimation for MIMO-OFDM systems and propose a spherical linear interpolator in closed-form for the beamforming codewords. We also suggest a hybrid interpolator using a simplified version of the derived interpolator. Simulation results show that the proposed schemes are efficient and competitive with respect to the feedback overhead and have low complexity.

Different from distributed baluns, active baluns have group delay variations in the lower bands related to inherent internal capacitances and resistance in transistors. A negative group delay (NGD) circuit is employed as a compensator of group delay variation for an ultra-wideband (UWB) active balun. First, three-cell NGD circuit is inserted into a simple active balun circuit for realizing both group delay compensation and return loss improvement. The simulated results show a group delay variation of 4.8 ps and an input return loss of above 11.5 dB in the UWB band (3.1-10.6 GHz). Then, a pair of one-cell NGD circuits is added to reduce the remaining group delay variation (3.4 ps in simulation). The circuit with the NGD circuits was fabricated on an InGaP/GaAs HBT MMIC substrate. The measured results achieved a group delay variation of 7.7 ps, a gain variation of 0.5 dB, an input return loss of greater than 10 dB, and an output return loss of larger than 8.1 dB in the UWB band.