The proposed high-power-factor converter is constructed with a flyback converter, and locates the energy-storage capacitor on the secondary side of the transformer. A high power-factor can be obtained without needing to detect any current, and the ZVS operation can be achieved without auxiliary switches. To make the best use of these advantages in the converter, ZVS operations and power-factor characteristics in the converter were analyzed. From the analytical results, the effective control method for achieving ZVS was examined. Using a bread-board circuit controlled by this method, a power-factor of 0.99 and a conversion efficiency of 88% were measured.

In this paper, we analyze overload and stability in the charge-pump phase locked loop (PLL). We propose a new computational model that can be applied for the precise estimation of the physical limits of charge-pump, the leakage current of loop filter and waveform distortion of charge-pump PLL operating in high speed. We derive the exact mathematical expressions of the parameters describing the steady-state behavior of the PLL as well as the transient-state behavior. Performance comparisons with the conventional model are provided through numerical results. Algorithms for approximate analysis is also provided. The new model is particularity useful for analyzing the cases that the charge-pump PLL operates in high- speed or the loop filter has large leakage current.

For traffic control in high speed ATM Networks Usage Parameter Control (UPC) plays an important role. The existing UPC schemes have some limitations. It is difficult to implement policy which involves monitoring vioations while guaranteeing QoS for the compliant connections-particularly with respect to bursty traffic sources. This is due to the difficulty in measuring the Sustained Cell Rate (SCR) and Maximum Burst Size (MBS) parameters simultaneously. To ensure prompt action against policy-violations, speedy detection is an important requirement. But the existing UPC schemes do not have a satisfactory response time. In this paper, we propose a new scheme called Markovian State-Dependent UPC schemes (MSDU) to police SCR and MBS parameter violation simultaneously with a satisfactory response time. The MSDU scheme is performed by using two virtual queues: 1) a Markovian State Dependent Service queue and 2) a Fixed Service queue. The discrete time analysis of the MSDU is carried out for a bursty source which is a Markov-Modulated Bernoulli Process (MMBP). The improved effectiveness of the proposed MSDU is clarified by a numerical comparison with UPC based on standard Leaky Bucket scheme.

This paper proposes a direct-sequence spread spectrum (DS/SS) communication system with a new diversity technique designed for indoor multi-path fading channels where path diversity isn't available. In this system, the transmitter sends a same signal from multiple antennas at the same time with intentional time delays, which allows the receiver to distinguish and combine the signals from different antennas. We also consider the combination of this scheme with the conventional receiving antenna diversity for additional diversity gain. Furthermore, it is found that the use of the multiple transmitting antennas decreases the effect of the multiple access interference.

In addition to additive thermal noise, a received direct-sequence spread spectrum (DS/SS) signal may suffer from intersymbol interference (ISI) and interference caused by cochannel narrowband users or other narrowband radio frequency interference (RFI). This paper presents a workable solution for removing narrowband interference (NBI) and reducing ISI or inter-chip interference (ICI) when the communication channel can be modeled as an FIR filter and the NBI comes from multiple CW tones, an AR-modeled Gaussian process, or a BPSK signal. Unlike earlier solutions, the proposed scheme is capable of performing the functions of NBI-rejection, ISI/ICI suppression and data detection (code despreading) simultaneously. It is easy to implement and, more importantly, it yields lower bit error rate (BER) and smaller mean squared error (MSE).

TPC (transmission power control) can compensate the near-far problem and so is a key technology of DS (direct sequence) -CDMA (code divison multiple access) systems. There are two kinds of TPC. One is closed loop and the other is open loop. In practical systems, both methods are used to compensate the variation in reception signal level. However, adoption of one simple TPC scheme is preferable from the viewpoint of transceiver configuration at the BS (base station) and MSs (mobile stations). Reception signal variation in wide-band DS-CDMA systems is shallower and we have the possibility of using only open loop as the TPC method. To evaluate the TPC accuracy of open loop, it becomes important to estimate the lower bound of TPC error because TPC error directly influences user capacity. This paper evaluates the lower bound of open loop TPC error by a theoretical analysis and laboratory tests; both results agree well. It is found that as the average power difference between paths increases, the lower bound of open loop TPC error increases. Ir is also found if the number of paths increases, the lower bound of open loop TPC error decreases. If the number of paths is 10 and the power difference between the nearest paths is less than 0.2 dB, the lower bound of open loop TPC error is larger than 1 dB. When the TPC error is larger than 1 dB, the reduction in user capacity is above 30%.

From the standpoint of reducing the electromagnetic (EM) absorption in the human head for portable telephones, a ferrite sheet is proposed to use as a protection attachment between the antenna and the head. By using an anatomically based head model and a realistic portable telephone model, the effects of the ferrite sheet on both the reduction of EM absorption and antenna radiation pattern are numerically analyzed by the finite-difference time-domain (FDTD) method. The results show that a ferrite sheet can result in a reduction over 13% for the spatial peak SAR averaged over one gram of tissue relative to a degradation below 0.6 dB for the antenna radiation pattern.

Many switching networks are currently designed to support ATM architectures. In this letter, we propose the performance improvement of a network called hybrid dilated banyan network with bypasses at the stage of 42 re-arrangeable output switch. Our letter also includes the performance analysis of the improved hybrid dilated banyan network.

An MT connector assembly machine has been designed and developed. The connector assembly time using this machine is about 30% less than with the conventional method. The MT connectors assembled employing this machine have a low connection loss and stable mechanical characteristics.