Reliable multicast is an interesting application of distributing data to lots of clients at the same time. In heterogeneous environment, it is necessary to adjust the transmitting rate corresponding to the bandwidth of receivers. Placed at a network bottleneck point, an active server can buffer the multicast packets and control the transmitting rate to the downstream multicast receivers independently so as to absorb bandwidth differences. If wireless and wired receivers coexist, the best position for the active server is at the edge of the wired and wireless links because the bandwidth of wireless receivers are lower than that of wired receivers. However, it is not enough that an active server only controls the transmitting rate in such environment because wireless receivers tend to lose packet by the wireless transmission error. This paper proposes a scheme in which the active server independently controls a reliable multicast scheme that is robust against packet loss due to wireless transmission error. Simulation results show that rate-based reliable multicast congestion control is more appropriate than window-based control for wireless links. We also show that FEC applied only to the wireless link improves the throughput of wireless multicast receivers. Finally, we show that combining rate-based reliable multicast congestion control scheme with FEC only for the wireless link makes reliable multicast more practical and friendly with TCP even if packets are lost due to transmission errors.

A simple modeling technique for symmetric inductors is proposed. Using the proposed technique, all model parameters for an equivalent circuit of symmetric inductors are easily calculated from geometric, process and substrate resistance parameters without using electromagnetic (EM) simulators. Comparison of simulated results with measured results verifies the effectiveness of the proposed modeling technique up to 5 GHz with center-tapped or non-center-tapped configurations.

The IMT-2000 service launched in 2001 in Japan is expected to popularize multimedia services such as videophone, visual mail, video, and music distribution. With the rapidly increasing demand for high-speed mobile multimedia and the need to support diversified requirements of users, wireless Quality of Service (QoS) resource management has become an important and challenging issue. In order to improve the system capacity and rate of satisfied users, in this paper, a novel wireless QoS resource management scheme is proposed to carry out radio resource cooperative control among base stations. Computer simulations indicate that the proposed QoS resource cooperative control exhibits superior performance over conventional ones, and that a higher rate of satisfied users is achieved.

The equidistortion principle[1] has recently been proposed as a basic principle for design of an optimal vector quantization (VQ) codebook. The equidistortion principle adjusts all codebook vectors such that they have the same contribution to quantization error. This paper introduces a novel VQ codebook design algorithm based on the equidistortion principle. The proposed algorithm is a variant of the law-of-the-jungle algorithm (LOJ), which duplicates useful codebook vectors and removes useless vectors. Due to the LOJ mechanism, the proposed algorithm can establish the equidistortion condition without wasting learning steps. This is significantly effective in preventing performance degradation caused when initial states of codebook vectors are improper to find an optimal codebook. Therefore, even in the case of improper initialization, the proposed algorithm can achieve minimization of quantization error based on the equidistortion principle. Performance of the proposed algorithm is discussed through experimental results.

Wireless LAN (WLAN) systems transmit and receive via a common frequency band. In this band, signals of other wireless applications operate on a WLAN beamformer as interferences, and so the problem in adaptive antenna is increasing the canceling performance in the presence of moving interference sources. The performance of conventional adaptive beamformer is severely degraded and the robust adaptive beamformer must be equipped with additional sensors to obtain desired performances. Therefore, in order to avoid having to install additional sensors, an efficient algorithm is necessary. In this paper, we introduce a fast adaptive algorithm with variable forgetting factor, which does not require any further additional modifications. Through computer simulations, we can obtain better performances than those of other techniques under a variety of operating conditions.

In this paper, we present a novel approach for efficient search of high-dimensional databases, such as video shots. The idea is to map feature vectors from the high-dimensional feature space into a point in a low-dimensional distance space. Then, a spatial access method, such as an R-tree, is used to cluster these points based on their distances in the low-dimensional space. Our mapping method, called topological mapping, guarantees no false dismissals in the result of a query. However, the result of a query might contain some false alarms. Hence, two refinement steps are performed to remove these false alarms. Comparative experiments on a database of video shots show the superior efficiency of the topological mapping method over other known methods.

Correct and quick generation of a membership function is the key point when we implement a real-time fuzzy logic controller. In this Letter, we presented two efficient VLSI architectures, one to generate triangle-shaped and the other to generate trapezoid-shaped membership functions. Simulation results show that our designs require lower hardware cost but achieve faster working rate.

We developed a new MU-type fixed optical attenuator for 4.5 mm pitch packaging. We succeeded in miniaturizing the attenuator by adopting a design employing an MUJ plug. This fixed optical attenuator achieved a tensile strength of greater than 70 N, which is the same as that of a conventional fixed optical attenuator, and also exhibited good environmental and mechanical durability. The new fixed optical attenuator can be used in existing communication devices in which 4.5 mm pitch MU adaptors are already installed.

A LiNbO3 piezoelectric actuator controls the Au-Au contact gap. The control accuracy of the actuator is within the sub-micron range. Contact voltage, contact current, displacement of electrodes and driving voltage of the actuator were continuously and synchronously recorded by an A/D converter and send to a computer. The measured oscillograph data for 1500 contact operation were processed by the computer. Factors of discharge and bridge phenomena were derived at a contact operation. The delay time between displacement and driving signal of the actuator increased when one side of electric contact were vibrated. The resonance was seen in the actuator, and the dependency to the current and the amplitude was seen.

This paper presents a modified microwave radio-thermometer (MRTM) with material characteristic estimator and multiple temperature conversion tables to measure subcutaneous temperature of a living body. This estimator provides a temperature retrieval unit with material characteristics such as permittivity, conductivity, thickness and geometry of the living body. The temperature retrieval unit with multiple temperature conversion tables can select one of the tables and compute temperature value corresponding to measured radiation power. In the experiments, it was shown that the radio-thermometer could reduce measurement errors of about 0.82 to 7.68 for the cases of distilled water and mixed liquid # 5 with thickness of 29.5 cm and 9.5 cm at the temperature of 37.

In this paper, we propose a modified CP-AFC (Cross-Product Automatic Frequency Control) algorithm to enhance coherent signal detection for WCDMA reverse link receiver. We introduce a moving average filter at the FDD input to decrease the noise effect by increasing the number of cross-products, since pilot symbol in WCDMA is not transmitted continuously. We also add normalization algorithm to overcome the conventional CP-FDD's sensitivity to the variance of input signal amplitude and to increase the linear range of S-curve. For rapid frequency acquisition and tracking, we adopt a multi-stage tracking mode. We applied the proposed algorithm in the implementation of WCDMA base station modem successfully.

In this paper, we try to establish a power law for contact resistance versus force Rc = KcFc-n , and we determine via experimental measurements and theoretical calculations, the constants n and Kc in the force range (1 mN-4 N) for bulk metal (Ag, Au, Pd, Ni) used in various applications (microswitches, connectors). The main experimental results of contact resistance are the occurrence of two decrease domains versus progressive load indentation. The first regime corresponds to the earlier touch of the coupon by the probe at force < 0.1 N. This elastic regime evolves to a plastic regime for medium force > 0.1 N. At the transition the exponent value n changes from 0.33 to 0.5 and induce Kc value increasing. Theoretical and computational approaches applied to the elasto-plastic model, confirm the occurrence of these two regimes. Although the calculated values of n are in good agreement with experimental values, some discrepancy between measured and calculated Kc values take place.

We propose an extended one-shot decorrelating detector (EOS-DD) which may be viewed as a generalized double window multiuser detector (DW-MD) for asynchronous direct-sequence code-division multiple-access (DS/CDMA) systems in frequency selective fading environments. The EOS-DD extends a processing window and the received signal over an extended window is utilized for decorrelating. The effects of the window size on BER performance are investigated by numerical analysis. Analysis and simulation show that the EOS-DD is superior to the one-shot decorrelating detector (OS-DD) and finite memory length truncated decorrelating detector (FIR-DD) in terms of noise enhancement and near-far resistance. It is also shown that the EOS-DD with window size 4 can provide significantly improved performance compared to the EOS-DD with window size 2.

This paper proposes a new dynamic multicast routing algorithm for layered streams. Since a layered multicast technique accommodates different types of users in the same multicast group, it helps to provide multicast services in a heterogeneous environment. However, this makes it difficult to construct an efficient routing tree when receivers join or leave a multicast session dynamically. In the proposed algorithm, we adopt a pre-determined path approach to handle such dynamic membership of a layered multicast session without the burden of much additional traffic. Simulation results show that the proposed algorithm can minimize the average multicast tree cost, and that it works well on large-scale networks and those with traffic heterogeneity and a small number of routing control messages.

An exact and an approximated reliabilities of a 2-dimensional consecutive k-out-of-n:F system are discussed. Although analysis to obtain exact reliability requires many calculation resources for a system with a large number of components, the proposed method obtains the reliability lower bound by using a combinatorial equation that does not depend on the system size. The method has an assumption on the maximum number of failed components in an operable system. The reliability is exact when the total number of failed components is less than the assumed maximum number. The accuracy of the method is confirmed by numerical examples.

A three-mode switched-LNA has been developed using a 0.25 µm SiGe BiCMOS technology. The LNA features low noise figure (NF) performance, while achieving both low dissipation power and low distortion characteristics. The proposed MOSFET switch incorporating a newly developed switch circuit with a triple-well structure, which changes the LNA's mode, provides a parasitic capacitance of just 0.52 times that of a conventional MOSFET switch. This results in a significant NF improvement, by 0.16-0.33 dB, for the three-mode switched-LNA compared to a conventional LNA. Extensive studies of the MOSFET switch with regard to the structural parameters and the doping profiles are reported. Experimental results and the overall performance of a trial IC incorporating the three-mode switched-LNA are also given.

Resource-demanding services such as Multi-media-on-Demand (MOD) become possible as Internet and broadband connections are getting more popular. However, as the sizes of multimedia files grow rapidly, storage of such large files becomes a problem. Since multimedia contents will generally become less popular with time, it is desirable to design a prediction algorithm so that the multimedia content can be unloaded from the server if it is no longer popular. This can relieve the storage problem in an MOD system, and hence spare more space for new multimedia files. In this paper, we analyse the MOD viewing trend in order to understand the viewing behaviour of users and predict the viewing trend of a particular category of multimedia based on the knowledge obtained from its trend analysis. In trend analysis, two additive regression models, exponential-exponential-sum (EES) and exponential-power-sum (EPS), are proposed to improve the fitness of the trend. The most suitable model will then be used for trend prediction based on four proposed approaches, namely Fixed Regression Selection (FRS), Continuous Regression Updating (CRU), Historical Updating (HU) and Continuous Regression with Historical Updating (CRHU). From the numerical results, it is found that CRHU, which is constructed by considering historical trend and new incoming data of viewing requests, is in general the best method in forecasting the request trend of a particular category of multimedia clips.

In the study, we build a system called Adaptive Visual Attentive Tracker (AVAT) for the purpose of developing a non-verbal communication channel between the system and an operator who presents intended movements. In the system, we constructed an HMM (Hidden Markov Models)-based TD (Temporal Difference) learning algorithm to track and zoom in on an operator's behavioral sequence which represents his/her intention. AVAT extracts human intended movements from ordinary walking behavior based on the following two algorithms: the first is to model the movements of human body parts using HMMs algorithm, and the second is to learn the model of the tracker's action using a model-based TD learning algorithm. In the paper, we describe the integrated algorithm of the above two methods: whose linkage is established by assigning the state transition probability in HMM as a reward in TD learning. Experimental results of extracting an operator's hand sign action sequence during her natural walking motion are shown which demonstrates the function of AVAT as it is developed within the framework of perceptual organization. Identification of the sign gesture context through wavelet analysis autonomously provides a reward value for optimizing AVAT's action patterns.

A simple configuration for millimeter-wave fiber-wireless transmission, with remote local-oscillator (LO) delivery from the central office, both for the uplink and for the downlink, and a simple, cost-effective, base-station solution is proposed. Under the assumption of using commercially available components and a conventional single-mode fiber (with dispersion of 17 ps/nm/km at 1.55 µm), our numerical results show that, with a laser linewidth of 150 MHz, a laser power of 0 dBm and an optical gain of only 6 dB, it is possible to transmit, without repeaters, data rates of 622 Mbit/s across about 18 km at a bit-error-rate of 10-9. By increasing the optical gain to 24 dB, the link length can be increased to approximately 67 km for a laser linewidth of 75 MHz and to 78 km for a laser linewidth 1 MHz.

In this paper, we first investigate the characteristics of movie contents over the Internet. As in the previous studies, we found the lognormal-distribution well fits the distribution of file size for the whole set of general movie contents. When we specifically focus on the subset that consists of movie trailers, however, it shows different distribution from the lognormal-distribution. Our analysis shows it is similar to an exponential-distribution. We here assume that movie trailers are one of the relevant contents for Contents Delivery Networks (CDN) or Peer-to-Peer (P2P) file exchange communities. We further studies the relationship between playing duration and file size for the movie trailers and we did not find any linear correlation among them. We next consider bandwidth requirements to retrieve movie trailer contents. Our objective is to make it possible for user to view the contents in real-time. Many previous studies investigate bandwidth requirement based only on the file size distribution. In this paper, we analyze the traffic design criteria for CDN or P2P by taking into account both of the results for the file size distribution and the relationship between playing duration and file size for movie trailers. Simulation studies reveal the impact for the bandwidth requirement.