Most smart cards based on the Java Card need an installer for deploying a new applet into its memory after the cards were issued. Installing the applet takes lots of time because of unique components downloading and hardware limitations. An efficient installation for applets in the Java Card platform is investigated. The proposed scheme could improve applet installation time significantly compared to the conventional scheme by fully utilizing available RAM space and could present the best a block size to be transferred between a terminal and JCRE.

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A coplanar waveguide (CPW) fed Ultra Wideband (UWB) slot antenna with reconfigurable rejection bands is presented. Specific band of the rejection is achieved by placing switching diodes over the rectangular slot in the ground plane at a position of effective length of λ/2 for the center frequency of the rejection band. The rejection of WiMax, IEEE 802.11a and HYPERLAN/2 bands can be achieved by switching the diodes. The simple configuration and low profile of the proposed antenna leads to easy fabrication that may be used in any wireless UWB device applications where reconfigurable rejection bands are required.

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This letter proposes a multithreaded pattern matching algorithm which can efficiently distribute the patterns to be searched on multiple threads to achieve rapid pattern matching operation. The proposed idea is designed to fully exploit thread-level parallelism to enhance searching speed. By distributing a large number of patterns over multiple threads, pattern matching procedure experiences less cache misses and shows better performance. In addition, we propose to sort the target patterns according to the alphabetic order to achieve efficient data decomposition. From detailed experiments and performance analysis, our algorithm shows remarkable performance gain compared to the original Wu-Manber algorithm.

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This paper presents the results of a novel ultra-wideband (UWB) annular elliptical antenna with multi resonant rings which are fed via coplanar waveguide (CPW). The proposed antenna exhibits an impedance bandwidth of 163% covering an ultra-wideband frequency range from 2 to 20GHz, with a return-loss performance of better than -10dB (S11 ≤ -10dB). Details of the antenna design, simulation and measured results are presented.

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This paper proposes an access control method for composite multimedia content in which only a single key is delivered to a user. The proposed method simultaneously controls access to each medium in one composite multimedia content in which a medium can be hierarchically encoded. This method introduces recursive hash chains for key generation so that the number of delivered key is reduced to one, whereas the conventional method having the above mentioned features has to deliver multiple keys to a user. The managed key in the proposed method is also reduced to one.

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A digital coreless maximum power point tracking (MPPT) circuit for thermoelectric generator unit is proposed and fabricated. The experimental and simulation results from the proposed MPPT circuit dealt with rapid variation of temperature and abrupt changes of load current have shown that the proposed method allows stable operation with high power transfer efficiency. The proposed MPPT circuit has a merit in cost and miniaturization of a system compared to conventional MPPT algorithms thanks to an analog tracking circuit without digital controller unit for calculating peak power point by iterative methods.

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A high gain W-shaped microstrip patch antenna is proposed and experimentally investigated. The patch antenna employs a new inverted W-shaped patch structure with meander probe feed technique. A prototype of the proposed antenna is fabricated and tested for validation. This low-profile antenna is operating for the frequency band of 1.84GHz to 2.29GHz. It exhibits an impedance bandwidth (2:1 VSWR) of 21.79% and a high gain of 10.46dBi at the frequency of 2.11GHz. The measured result shows the stable radiation characteristics, including a low cross-polarization level below -20dB in both planes.

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The intermodal dispersion of few-mode fiber limits the propagation distance of mode division multiplexing (MDM). We numerically investigate the propagation constant and group velocity of few-mode fibers. The refractive index profile of few-mode fibers should be designed to achieve long and dense MDM transmissions with digital coherent receivers.

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In order to maximize the throughput in cognitive radio when primary communication system is an OFDM system, the optimal spectrum sensing is addressed. Firstly the single user sensing is discussed, and it is proved that the optimal sensing time that maximizes the throughput exists. In addition, the cooperative sensing using k-out-of-N fusion rule is considered. By analyzing the mathematical model of the throughput, a joint searching method is proposed to obtain the optimal sensing time and fusion rules which can maximize the throughput. In the simulation results, the correctness of theoretical analysis is verified.

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We propose a parameterized modeling technique for wireless relay networks based on IEEE 802.16j standard operating in non-transparent mode. Our modeling is able to represent the downlink throughput in a concise closed form and thus very useful for predicting the downlink system throughput with a few estimated parameters. The key parameters include α which represents how much portion of the whole data from MR-BS to be transmitted over access link without going through relays (0 ≤ α ≤ 1). Another key parameter is r, which determines how much portion of DL (down link) zone is used for access (0 ≤ r ≤ 1). We also add a parameter θ_i, which determines how much portion of the data to be relayed via RSi (0 ≤ θ_i ≤ 1). Our contribution lies in that our formula can be used to estimate the expected downlink system throughput without going through extensive simulation in the early design stage for IEEE 802.16j relay systems. Optimization can be easily performed using our formula.

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This paper presents a novel backoff algorithm based on a Network Allocation Vector (NAV) for the IEEE 802.11 Distributed Coordination Function (DCF). In the DCF, the NAV indicates the amount of time that a medium will be reserved by other nodes, so it provides an accurate estimation of neighbor nodes activities around a node. Thus, the proposed scheme dynamically adjusts the contention window according to the variation of neighbor nodes activities, which is estimated by NAV measurements. Simulation results demonstrate that the proposed scheme outperforms existing schemes in terms of total throughput and fairness between nodes.

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The stability of a power system significantly influences the reliability of its operation. Therefore, it is important to understand how stability problems arise in power systems. An equivalent mechanical model of an electric power system is proposed by NODA to help understand stable/unstable operation of a power system, and its validity is qualitatively confirmed. This study provides quantitative evaluation of the equivalent mechanical model to assess the analogy with electric power system behavior. To this end, the steady-state stability, which is the local stability about an equilibrium point, is evaluated experimentally and numerically for the equivalent mechanical model and an electric power system model.

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In this paper, a new four-moduli set {2²ⁿ, 2²ⁿ⁺¹-1, 2^n/2+1, 2^n/2-1} for even n is introduced. This moduli set has 5n-bit dynamic range and well-formed moduli which result in a high speed RNS arithmetic unit. Furthermore, an efficient adder-based reverse converter is proposed for this moduli set by using New Chinese remainder theorem 2 (New CRT-II) algorithm. The proposed moduli set has a high speed RNS arithmetic unit and a reverse converter with lower hardware cost and delay in comparison to the recently introduced moduli sets {2ⁿ-1, 2ⁿ, 2ⁿ+1, 2²ⁿ⁺¹-1} and {2ⁿ, 2²ⁿ⁺¹-1, 2^n/2-1, 2^n/2+1, 2ⁿ+1} with the same dynamic range.

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A novel non-coherent binary phase shift keying (BPSK) demodulator featuring ultra-low power and high data rate is presented for inductively powered biomedical implants. The circuit is designed in the 0.18µm standard CMOS technology. Simulation results show that at a data transmission rate of 16Mbps, the power consumption of the circuit is as low as 6.3µW and 1.96µW at a supply voltage of 1.8V and 1V, respectively. The proposed demodulator tolerates a relatively large frequency shift for the input signal and operates properly in all process corners.

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A CPW-fed ultra-wideband antenna with dual band-notch characteristics is realized experimentally and numerically. Two notched frequency bands are obtained by utilizing a tuning stub between the fork-like radiation element and a rectangle slot in the CPW ground plane. The two notched bands can be controlled by adjusting the length of the tuning stub and the length of the rectangle slot. Experimental and numerical antenna shows that the proposed antenna, with compact size of 21×28mm², has an impedance bandwidth ranging from 3.1GHz to 10.6GHz for voltage standing-wave ratio less than 2, expect two notch band frequency 5GHz-6GHz for WLAN and 7.7GHz-8.5GHz for X-band for satellite and military applications.

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