In this paper, the co-existence of TDMA and W-CDMA spectrum sharing system (TDMA/W-CDMA overlaid system) with cellular architecture is discussed. In this system, both systems share the same frequency band to improve the spectrum efficiency. Overall rate, bit error ratio (BER) and spectrum efficiency of the system are calculated for the forward link (down-link) in the presence of AWGN channel. Taking into account the path loss and shadow fading loss in this system with cellular architecture, W-CDMA applying interference cancellation (IC) shows a substantial difference in spectrum efficiency, the overlaid system can provide a greater overall rate and higher spectrum efficiency than a single multiple access-based system such as TDMA system or W-CDMA system. The interference cancellation can significantly improve BER of the spectrum overlaid system.

A noise suppression algorithm with high speech quality based on weighted noise estimation and MMSE STSA is proposed. The proposed algorithm continuously updates the estimated noise by weighted noisy speech in accordance with an estimated SNR. The spectral gain is modified with the estimated SNR so that it can better utilize the improvement in noise estimation. With a better noise estimate, a more correct SNR is obtained resulting in the enhanced speech with low distortion. Subjective evaluation results show that five-grade mean opinion scores of the new algorithm with and without a speech codec are improved by as much as 0.35 and 0.40 respectively, compared with either the original MMSE STSA or the EVRC noise suppression algorithm.

We developed a distributed control algorithm to solve the problem of a trade-off between transient response and stability. We applied it to a congestion control algorithm for transmitting best-effort packets such as transmission control protocol (TCP) packets over the Internet. A new transmission power control algorithm suitable for transmitting best-effort packets over the wireless Internet was also developed using the distributed control algorithm. We showed that in a steady state, TCP connections can use the bandwidth efficiently over both wired and wireless Internet when the proposed control algorithms are used. The transient response was also evaluated and it was found that the packet transmission rate and the transmission power adjusted by the proposed control algorithms converge to a steady state faster than when adjusted by conventional control algorithms while maintaining the stability of network systems.

In general, the attenuation characteristics of band-pass filters can be improved by generating attenuation poles in the stop band. In this paper, a design method for a planar band-pass filter with attenuation poles based on a half-wavelength resonator is proposed. According to this design, the attenuation poles can be obtained at any desired frequency by means of coupling structures. Two kinds of filter with the characteristics of steep skirt and wide stop-band were designed and fabricated with the result that the validity of the design method was demonstrated. Therefore, a filter with excellent attenuation characteristics for various applications can be achieved.

We design a four-reflector offset antenna satisfying the cross-polarization elimination condition and the broadband characteristics condition which consists of one primary horn, three subreflectors and one main reflector. The cross-polarization elimination condition for the four-reflector offset antennas is expressed by the equations of hyperbolas with the coordinate axes of the reciprocal of equivalent focal lengths. The configurations of the reflector system are derived simply from the graphical representation because four-reflector offset antennas satisfying these relationships exist on the hyperbolas with the coordinate axes of the reciprocal of equivalent focal lengths. Furthermore, we clarified that the derived condition for having planar phase front applying the broadband characteristics condition is independent of frequency. An actual design example for the four-reflector offset antennas satisfying the cross-polarization elimination condition and the condition for having planar phase front, both of which are independent of frequency is shown. The design method using the graphical representation is simpler than that of the tri-reflector offset antennas.

The radio-frequency thermal noise in fully-depleted (FD) silicon-on-insulator (SOI) MOSFETs and bulk MOSFETs is theoretically examined using a distributed-transmission-line model. It is shown that the thermal noise in a scaled-down SOI MOSFET is basically smaller than that in a scaled-down bulk MOSFET in a wide frequency range. In the radio-frequency range, parasitic resistances in source and drain don't yield a remarkable contribution to the difference in output thermal noise power between scaled-down bulk MOSFETs and scaled-down SOI MOSFETs. However, the output thermal noise of scaled-down SOI MOSFETs with a finite parasitic resistance is smaller than that of scaled-down bulk MOSFETs because of smaller channel capacitance.

This paper proposes a signal-to-interference power ratio (SIR) measurement method that employs the transmission gap of a data channel (TGDC) interval for precise link adaptation, in order to eliminate the influence of severe multipath interference (MPI) from a shared packet channel and to decrease further the instantaneous variations in interference components for high-speed packet transmission in the forward link using adaptive data modulation associated with the multipath interference canceller (MPIC). Computer simulation results elucidate that the required received signal energy per chip-to-background noise power spectrum density ratio (Ec/N0) based on the SIR measurement employing TGDC at the throughput of 4.2 Mbps is decreased by approximately 2.0 dB compared to the conventional method without TGDC using chip-based interference power measurement for the number of paths L = 1, and by approximately 1.5 dB compared to the conventional method using symbol-based interference power measurement for L = 2, respectively. Therefore, we show that the adaptive data modulation with the SIR measurement exploiting the TGDC interval achieves almost the maximum (i.e., almost ideal selection) throughput, without changing the SIR measurement method according to the propagation conditions such as the number of multipaths.

Detection loss due to phase error in a carrier tracking loop is analyzed and simulated for a code division multiple access system with BPSK and QPSK modulations in a Rayleigh fading channel. For a specific BER, the detection loss due to phase error is defined as an increase of required SNR to maintain the same BER without phase error. A nonlinear Fokker-Planck method is employed to analyze first-order PLL (phase locked loop) performance. From the simulation results, it is confirmed that the phase noise induces significant detection loss, which eventually leads to degradation of the BER performance.

In this semi-tutorial paper, the reliability-based decoding approaches using the reprocessing of the most reliable information set are investigated. This paper somehow homogenizes and compares former different studies, hopefully improving the overall transparency, and completing each one with tricks provided by the others. A couple of sensible improvements are also suggested. However, the main goal remains to integrate and compare recent works based on a similar general approach, which have unfortunately been performed in parallel without much efforts of comparison up to now. Their respective (dis)advantages, especially in terms of average or maximum complexity are elaborated. We focus on suboptimum decoding while some works to which we refer were developed for maximum likelihood decoding (MLD). No quantitative error performance analysis is provided, although we are in a position to benefit from some qualitative considerations, and to compare different strategies in terms of higher or lower expected error performances for a same complexity. With simulations, however, it turns out that all considered approaches perform very closely to each other, which was not especially obvious at first sight. The simplest strategy proves also the fastest in terms of CPU-time, but we indicate ways to implement the other ones so that they get very close to each other from this point of view also. On top of relying on the same intuitive principle, the studied algorithms are thus also unified from the point of view of their error performances and computational cost.

The purpose of this study is to show the chaotic features of rhythmic joint movement. Depending on the experimental conditions, one (or both) elbow angle(s) was (were) measured by one (or two) goniometer(s). Pacing was provided for six different frequencies presented in random order. When the frequency of the pace increased, the fractal dimension and first Lyapunov exponent tended to increase. Moreover, the first Lyapunov exponent obtained positive values for all of the observed data. These results indicate that there is chaos in rhythmic joint movement and that the larger the frequency, the more chaotic the joint movement becomes.

In this paper, we propose the code orthogonalizing filter (COF) based adaptive array antenna using sample matrix inversion with common correlation matrix (CCM-SMI) of time domain signals for multicarrier DS/CDMA systems. The conventional array antenna system calculates the weight using the correlation matrix of individual subcarrier's signals. On the other hand, our proposed system calculates the weight using the correlation matrix of time domain signals before FFT operation, so it can reduce the calculation time and the complexity of weight calculation than the conventional scheme, to maintain the system performance. Moreover, we consider the code orthogonalizing filter to reduce the demerit of adaptive array antenna system using sample matrix inversion algorithm with common correlation matrix that requires heavy computational complexity while the signal environment frequently changes. Our proposed system obtains more accurate channel response vector using COF than that of the conventional CCM-SMI based on the matched filter, without increasing the matrix size. The performance is evaluated in term of bit error probability. From the analysis and simulation results, it is shown that our proposed scheme achieves better BER performance than that of the conventional system.

In an orthogonal frequency division multiplexing (OFDM) system, the bit error performance is degraded in the presence of multiple propagation paths whose excess delays are longer than the Guard Interval (GI), because the orthogonality between subcarriers cannot be maintained. Therefore, the GI has to be long enough for an expected delay spread of the channel. On the other hand, a long GI causes a decrease in transmission efficiency. In this paper, we propose a new OFDM demodulation method with a variable effective symbol duration, in order to improve the bit error performance in the presence of multipaths whose excess delays are longer than the GI. The proposed method can realize more stable radio communication systems under a multipath propagation environment even if a propagation path whose excess delay is longer than the GI exists. In other words, the proposed method can improve transmission efficiency without performance degradation by a shortened GI under the same environment. The principle of the proposed method is explained, and the bit error probability of the proposed method is analyzed theoretically in an AWGN channel and a multipath fading channel. The performance of the proposed method is then evaluated by computer simulation. The results show that the proposed method improves the system availability under more various multipath fading environments without changing the system parameters.

This paper reviews the advantages of the silicon three-dimensional MMIC technology such as low loss transmission lines, high integration level, and high Q-factor on-chip inductors. Coupled to the masterslice concept, this technology also offers simple design procedure, short turn-around-time, low cost, and potential integration with LSI circuits. A K-band amplifier and an up-converter demonstrate the high frequency operation and low-power consumption benefits of the Si 3-D MMIC technology. A C-band Si-bipolar single-chip transceiver is proposed to illustrate the high integration level offered by the masterslice concept. Finally, the recent advances we achieved toward high Q-factor on-chip inductors provide the design of the S-band low noise amplifier presented in this paper.

This paper investigates the optimum adaptive antenna array beam forming (AAA-BF) configuration considering the diversity effect provided by transmit diversity (TD) in a multipath fading channel in the W-CDMA forward link. Computer simulation results show that the required transmit signal energy per bit-to-background noise power spectrum density ratio (Eb/N0) at the average block error rate (BLER) of 10-2 using AAA-BF coupled with TD is decreased by approximately 1.0 dB compared to that of AAA-BF assuming the identical number of total antennas when the capacity, i.e., the number of simultaneously accommodated users with the transmission power proportional to the symbol rate, normalized by processing gain, Pg, is below approximately 20%. However, we find that in an interference-limited channel, when the capacity normalized by Pg is above approximately 30%, AAA-BF employing all antennas accommodates a larger capacity compared to AAA-BF coupled with TD because of a sufficient interference suppression effect due to a much narrower beam width despite the absence of the antenna diversity effect. This paper also elucidates in a multi-cell model that AAA-BF employing all antennas can accommodate approximately 1.5 times more users with the average BLER of 10-2 and with the outage probability of 5%, compared to the case with AAA-BF coupled with TD, when the total number of antennas is 8.

In this paper, we analyze the performance of a bulk handoff scheme for mixed traffic in integrated voice/data wireless mobile networks in which new and handoff voice/data calls are accepted based on prioritization of handoff requests. If fewer channels than handoff calls are available in the target cell, some handoff calls are terminated without queuing. A higher priority is given to voice handoff calls than to data handoff calls. A multidimensional birth-death process model is presented to analyze the bulk handoff performance of mixed traffic. A numerical analysis of system performance is presented to evaluate the blocking probabilities of new voice and data calls, handoff failure probabilities, and the forced termination probabilities of voice/data handoff calls.

The optical pulses of 50 MHz has been obtained from an organic light emitting diode (OLED) based on the Alq3 emissive layer with the active area of 0.01 mm2. We demonstrate that the OLEDs can be applied to fields of optical communication as the electro-optical conversion device for transmitting the signals of moving picture.

It has been known that the cell loss ratio (CLR) characteristics of the multiplexed traffic depend on the arrangement of I-picture starting times of individual variable bit rate (VBR) MPEG video sources. In this paper, we propose a simple yet accurate traffic model for the multiplexed VBR MPEG video to calculate the CLR at an ATM multiplexer when the arrangement of the I-picture starting times of individual sources is given. In the proposed model, in order to represent the arrangement of the I-picture starting times, each picture type (I-, P-, or B-picture) of individual source is modeled by the arrival rate histogram, and the multiplexed video traffic is modeled by the convolution of the arrival rate histograms of the pictures that comprise the multiplexed traffic. Using the proposed traffic model, we propose an analytical method to calculate the CLR of the multiplexed VBR MPEG video at an ATM multiplexer. Simulation results show that the proposed method can calculate the CLR more precisely and efficiently than other existing methods.

We proposed the conduction mechanism of organic light-emitting diode (OLED) using a one-dimensional discontinuous model. We assumed that each emitting molecule corresponds to a hopping site according to the actual charge transfer between adjacent molecules. Both carrier mobility of Alq3 and barrier heights for each carrier were derived from experimental data. We calculate transient behavior of carrier, field, and exciton distribution. Both carrier injections assumed the Schottky injection. In the previous results, when we assumed that calculated current density fit the experimental one in the current density field curve, calculated light-emission intensity did not fit the experimental one in the light-emission field curve. Furthermore, the slope of the calculated light emission-field curve is too small to fit the experimental one. In the previous study, hopping distance was assumed to be 1 nm. In this study, it is assumed to be 1.7 nm. We consider that field dependence of electron injection is too weak to explain only the Schottky emission. When the electron injection is assumed to be both Schottky emission and Fowler-Nordheim emission calculated light-emission field as well as the current-density field curves were fit to the curve of each experimental characteristics.

In this paper, we discuss the applicability of H filtering algorithm for a decision feedback equalizer (DFE) in mobile communications environments. A comparison of bit error rate (BER) performance between a H2 filtering (recursive least squares) algorithm-based and an a priori H filtering algorithm-based fractionally-tap-spaced DFEs in various fading channels is presented. Against, our results are rather pessimistic of the H equalizer, namely, as compared with the H2 equalizer, at most the same or a little better BER performance of the H equalizer is obtained only when the ratio of the average received energy per bit to the white noise power spectral density and the normalized fading rate are large enough, especially in Rician fading channels. Moreover, the H equalizer has the problems of how to choose an appropriate prescribed positive value and computational complexity, therefore it may not be considered as an attractive alternative to the H2 equalizer for wireless communications systems.

A base model should be transmitted first in progressive transmission schemes, and its transmission delay dominates initiation time for rendering. To reduce the initiation time, we restructure the base model to transmit visible vertices and triangles for some specific viewpoints first, and therefore clients can start rendering when parts of model file are received. Simulation results show that only 37.4% - 51.3% of model file are required to start rendering, and hence the initiation time is significantly reduced.