This paper evaluate the performance of a PN (pseudonoise) code acquisition for a direct-sequence/code-division-multiple-access (DS/CDMA) system in a mobile satellite environment. The acquisition scheme considered consists of a parallel matched-filter and a FFT processor. The uplink of mobile satellite channel is modeled as shadowed Rayleigh fading channel. The effects of power control error and shadowing are considered in the analysis of acquisition performance. It is shown that the power control error causes acquisition to be slower than the case of perfect power control, and for high SNR/chip, the effect of power control error becomes less significant. It is also shown that the case with heavy shadowing takes longer time to achieve acquisition than that with light shadowing. For the subinterval-based PN code search, the parallel MF scheme is thought to be more appropriate than the serial MF scheme at the cost of complexity. The analysis in the paper can be applied to the uplink of a DS/CDMA system for packet-type services in a mobile satellite channel.

Next generation wired/wireless networks will be based on IP technology. In the IP based networks, it is crucially required to support seamless mobility especially for proving real-time services in the mobile environment. The conventional Mobile IP protocols cannot satisfy such seamless mobility requirements for real-time services. Therefore various extensions of Mobile IP are being proposed. In this paper, we propose a new handover scheme to enhance the existing tunnel-based fast handover method, which is a typical Mobile IP extension to support seamless mobility. It is shown that the proposed method reduces the traffic overhead in the networks. It is expected that the proposed method will be particularly useful in the IP-based networks in which there are a number of users simultaneously using the long-lived real-time services, or in the condition that the traffic overhead is considered as a critical performance measure.

Rate compatible (RC) codes are used for adaptive coding schemes or hybrid ARQ schemes in order to adapt varying channel conditions. This can improve overall service quality or the system throughput. Conventional RC codes have usually been designed on the basis of convolutional codes. This letter proposes an efficient RC code based on block codes. We use a high dimensional product code and divide it into the information block and a number of parity blocks. We form RC product codes using various combinations of these blocks. Because we can decode the RC product codes iteratively, these result in block turbo codes and they can be used efficiently for hybrid ARQ schemes.

Today's complicated and heterogeneous telecommunication network environments need fully-integrated, cost-effective, user-friendly management systems. When developing such management systems in distributed environments, many telecommunication companies are carefully adopting CORBA and Java technologies. CORBA technology enables developers to create and manipulate distributed management system components easily while Java technology liberates human users from complicated and proprietary management system interfaces. In this paper, we propose a TMN-based integration framework for distributed network management by combining both CORBA and Java technologies. The framework generalizes a logically-layered architecture from the management agents layer to the user interface layer. It also provides generalized TMN management interfaces using inter-domain gateway systems for coordinating heterogeneous management protocols. By using these interfaces, TMN management function components can be easily constructed as CORBA objects to provide powerful TMN management services to administrators via user-friendly Web browsers. On the basis of this framework, we have designed and implemented a TMN alarm surveillance system which realizes our framework.

Experimental and theoretical studies of light coupling to various magnetic nanostructured media and nanocomposites are briefly reported. Enhancement of the magneto-optical response is shown to occur when the constitutive materials of photonic crystals are magnetic. Transmission and reflection types of 1D magnetophotonic crystals (MPCs) have been studied. New possibility to enhance the magneto-optical response has been found when utilizing localized surface plasmon resonances in bismuth-substituted yttrium iron garnet (Bi:YIG) films impregnated with Au nanoparticles. Examples of integrated optic devices are discussed in which functional elements are 1D and 2D magnetophotonic crystals.

We propose a new frequency and frame synchronization technique for orthogonal frequency division multiplexing (OFDM) systems in frequency domain by using the channel information. The proposed frequency synchronization scheme shows optimal performance. Also it is shown that the proposed frame synchronization scheme has significantly enhanced performance improvement and wide estimation range.

In the integrated Wireless LAN (WLAN) and cellular networks, power efficiency is one of the most important aspects as in existing wireless networks. Especially, we note that in the idle state, a mobile device with dual interfaces needs to receive periodic beacons from the access point and downlink control information from the base station, resulting in significant power consumption. To save the power, we propose a power saving scheme with Hibernation mode to completely turn off the WLAN interface during the idle state, instead of entering Power Save (PS) mode and turn it on only when there is a need to receive data. However, if the WLAN interface is turned on even for a momentary traffic, it must repeat turning on and off continuously, dissipating power. Thus, we also develop a Mobile IPv6 (MIPv6)-based signaling to turn on the WLAN interface for long-lived traffic. It is shown via simulations that the proposed power saving scheme results in better power efficiency.

Current research trends in computer vision have tended towards achieving the goal of recognizing human action, due to the potential utility of such recognition in various applications. Among many potential approaches, an approach involving Gaussian Mixture Model (GMM) supervectors with a Support Vector Machine (SVM) and a nonlinear GMM KL kernel has been proven to yield improved performance for recognizing human activities. In this study, based on tensor analysis, we develop and exploit an extended class of action features that we refer to as gradient-flow tensor divergence. The proposed method has shown a best recognition rate of 96.3% for a KTH dataset, and reduced processing time.

In this paper a new electromagnetic (EM) interference analysis is proposed using the total harmonic distortion (THD) measurement of the audio signal by the 900 MHz cordless telephones. The cordless telephone network in 900 MHz was built up to be weak in EM interference. 400 and 800 Hz of the sine-wave signal were used in transmitter (TX) system, and the receiver (RX) system was exposed to the EM interference. The THD value varies as the level of the exposed EM interference changes. The model of the cordless telephone also affects the THD value. By using fluctuation of the THD value depending on the amount of the exposure, the threshold value of the interference electric field strength was derived. Based on the derived threshold value of the electric field strength, validity of the regulation value for low power radio devices by CISPR 22 [CLASS B] and FCC is discussed.

A method for fast but yet accurate performance evaluation of processor architecture is mostly desirable in modern processors design. This paper proposes one such method which can measure cycle counts and power consumption of pipelined processors. The method first develops a trace-driven performance simulation model and then employs simulation reuse in simulation of the model. The trace-driven performance modeling is for accuracy in which performance simulation uses the same execution traces as constructed in simulation for functional verification. Fast performance simulation can be achieved in a way that performance for each instruction in the traces is evaluated without evaluation of the instruction itself. Simulation reuse supports simulation speedup by elimination of an evaluation at the current state, which is identical to that at a previous state. The reuse approach is based on the property that application programs, especially multimedia applications, have many iterative loops in general. A performance simulator for pipeline architecture based on the proposed method has been developed through which greater speedup has been made compared with other approaches in performance evaluation.

In this paper, a smart dressing system was implemented based on flexible pH sensors that can monitor the infection of a wounded area by tracking the pH value of the area. Motivated by the fabrication process widely used for semiconductors, the flexible pH sensor fabrication process was devised with a polyester (PET) film and a Si wafer, which deposits Au and Ag on a PET film. Because the electrodes are comprised of a working electrode and a reference electrode, the reference electrode was fabricated by synthesizing the Polyaniline (PANI) on Ag/AgCl, while the pH sensor has four channels to evenly measure the pH value in a wide area. The smart dressing system was constructed with four pH sensors, a single temperature sensor, a level shifter, a regulator, an analog-to-digital converter (ADC), and a monitoring PC. The measurement results show that our smart dressing system has a size of 5×5cm2 and can monitor the pH value range found in [3,9] with a sensitivity slope of 50mV/pH.

We investigated an analogue modulation of magneto-optic spatial light modulator (MOSLM). For enhancement of the modulation from the voltage-driving MOSLM, magnetostriction and saturation magnetization of magnetic garnet films and piezoelectric constant of PZT films were investigated. The performance was expected to be improved by using Bismuth, Dysprosium and Aluminum substituted Yttrium Iron garnet, which effective magnetic field showed 20 times higher than Yttrium Iron garnet.

Switched parasitic capacitors of sleep blocks with a tri-mode power gating structure are implemented to reduce on-chip resonant supply noise in 1.2 V, 65 nm standard CMOS process. The tri-mode power gating structure makes it possible to store charge into the parasitic capacitance of the power gated blocks. The proposed method achieves 53.1% and 57.9% noise reduction for wake-up noise and 130 MHz periodic supply noise, respectively. It also realizes noise cancelling without discharging time before using parasitic capacitors of sleep blocks, and shows 8.4x boost of the effective capacitance value with 2.1% chip area overhead. The proposed method can save the chip area for reducing resonant supply noise more effectively.

In this letter, the amount of interference and an analytic methodology from a combination of Korea's LTE system and Japan's digital terrestrial TV broadcasting system using the 700 MHz frequency band are established when considering a practical deployment of both systems. We performed Monte-Carlo simulations on the throughput loss to evaluate how much interference radiating from Japan's DTV is imposed on the Korean LTE system. The results of the established methodology can be used as a guideline for allowing the deployed LTE system to avoid an unacceptable amount of interference.

In this letter, we propose a more secure modeling and simulation approach that can systematically detect state variable corruptions caused by buffer overflows in simulation models. Using our approach, developers may not consider secure coding practices related to the corruptions. We have implemented a prototype of the approach based on a modeling and simulation formalism and an open source simulator. Through optimization, the prototype could show better performance, compared to the original simulator, and detect state variable corruptions.

Fairness among uplink and downlink TCP flows can not be supported in infrastructure IEEE 802.11 Wireless LANs using the distributed coordination function (DCF). In order to resolve this problem, we propose the Distributed Access Time Control (DATC) scheme, in which each station controls the rates of its TCP flows based on channel access time. The DATC scheme can provide per-station fairness even when the number and direction of flows in each station are different. This scheme can be simply implemented in mobile stations without having to modify the access points. The properties of the proposed scheme are investigated and its effectiveness is verified through simulations.

Digital hearing aid users often complain of difficulty in understanding speech in the presence of background noise. To improve speech perception in a noisy environment, various speech enhancement algorithms have been applied in digital hearing aids. In this study, a speech enhancement algorithm using modified spectral subtraction and companding is proposed for digital hearing aids. We adjusted the biases of the estimated noise spectrum, based on a subtraction factor, to decrease the residual noise. Companding was applied to the channel of the formant frequency based on the speech presence indicator to enhance the formant. Noise suppression was achieved while retaining weak speech components and avoiding the residual noise phenomena. Objective and subjective evaluation under various environmental conditions confirmed the improvement due to the proposed algorithm. We tested segmental SNR and Log Likelihood Ratio (LLR), which have higher correlation with subjective measures. Segmental SNR has the highest and LLR the lowest correlation of the methods tested. In addition, we confirmed by spectrogram that the proposed method significantly reduced the residual noise and enhanced the formants. A mean opinion score that represented the global perception score was tested; this produced the highest quality speech using the proposed method. The results show that the proposed speech enhancement algorithm is beneficial for hearing aid users in noisy environments.

In this letter, an improved residual symbol timing offset (STO) estimation scheme is suggested in an orthogonal frequency division multiplexing (OFDM) based digital radio mondiale plus (DRM+) system with cyclic delay diversity (CDD). The robust residual STO estimator is derived by properly selecting the amount of cyclic delay and a pilot pattern in the presence of frequency selectivity. Via computer simulation, it is shown that the proposed STO estimation scheme is robust to the frequency selectivity of the channel, with a performance better than the conventional scheme.

A new matched-filter (MF) acquisition scheme with adaptive threshold is proposed for a frequency-hopped/spread-spectrum multiple-access (FH/SSMA) system. Detection and false alarm probabilities are derived for combined interference environments. The combined interference consists of partialband noise jamming or tone jamming, multiple access interference (MAI), multipath interference, and thermal noise. We use Gaussian approximation for modeling the MAI and multipath interference. Equal power assumption of the users is employed which is typically used in the SSMA system analysis. In the proposed scheme, MF output is compared to an adaptive threshold determined by the number of jammed frequency slots. It is shown that the proposed adaptive-threshold acquisition scheme achieves higher detection probability and lower false alarm probability than a conventional fixed-threshold scheme for each jammed fractional bandwidth, JSR, the number of multipaths, and the number of users. It is also shown that adaptive threshold achieves faster acquisition and higher packet throughput than fixed threshold in application to FH/SSMA packet radio system.

This paper discribes a shared medium access control protocol for residential home and small business customer ATM network application with distributed high-speed multimedia services. This protocol offers global fairness for the whole network with a CG (Centralized Grant) signal and, at the same time, offers local fairness between nodes with DG (Distributed Grant) signals. The DG signal is only meaningful to the next neighboring node. The local fairness is kept between two nodes in distributed way, but this distributed local fairness helps to keep the global fairness. Because the DG signal is related to the passed DG signal from the neighbor node. This protocol is rather simple but shows high performance than the already announced protocols.