Standard Site Method (SSM) is theoretically analyzed using matrix representations to examine its validity and develop an improved method. The analysis reveals that the SSM yields an antenna factor specifically related to the effective load impedance presented by the cable and associated devices which are disconnected from the antenna during the SSM site attenuation measurements. Therefore, an additional conversion is required to determine the desired antenna factor under actual load conditions. It is also concluded that the SSM is not applicable to antennas having height-dependent antenna factors. In addition, the SSM correction factors are found to be theoretically inappropriate. Uncertainty of the antenna factor obtained using the SSM is discussed and the required antenna separation distance is investigated. To improve the existing SSM, it is proposed that both transmitting and receiving antennas are placed at the same height during the site attenuation measurements. Experiments exhibit the superiority of the improved method.

To support high bit rate and high quality indoor radio communication systems, we have to solve intersymbol interference (ISI) problem caused by frequency-selective fading. Recently multi-carrier modulation technique is considered to be one of the effective methods for this problem. In this paper we propose Partial Frequency ARQ (Automatic Repeat reQuest) system which can achieve effective ARQ scheme for multi-carrier packet communication. This system operates partial retransmission of erroneous power faded packets, and it is superior to the traditional ARQ systems. Furthermore two different protocols are examined for this system: Static Carrier Assignment (SCA) and Dynamic Carrier Assignment (DCA). By computer simulation we found that DCA method can achieve better performance than SCA in terms of both throughput and packet transmission delay.

CDMA cellular land network (CCLN) consists of base stations connected to selector bank subsystem. In the case of considering only the voice traffics, CCLN can be designed based on E1/T1 physical line and HDLC protocol with fixed or variable length. However, it is necessary to support not only voice but also data traffics in CDMA cellular system. Thus, it is needed to use physical lines efficiently to increase bandwidth efficiency and transmission speed. However, the conventional CCLN has some problems that the bandwidth is wasted because each BTS has its own private line. In this paper, the method using Distributed Queue Dual Bus (DQDB) Metropolitan Area Network (MAN) as a CDMA interconnect subsystem (CIS) is considered, and the performances of conventional and proposed methods constructing CIS are analyzed by computer simulation. According to the simulation results, if the traffics from all mobile stations are uniformly distributed among all BTSs, the performances of both conventional and proposed methodology have turned out to be almost equal. However, the performance of methodology using the DQDB MAN is much better than that of conventional method, in the case that the traffics from all mobile stations are nonuniformly distributed.

A subharmonic injection-locked oscillator (ILO) MMIC chain is proposed for the local oscillators and synthesizers used at millimeter-wave frequencies. A fabricated, primary 11-GHz-band injection-locked oscillator MMIC for the first stage ILO in the ILO-chain MMIC, achieves a wide subharmonic-injection-locking range at the subharmonic factors, 1/n (n=1, 2, 3, ), of 1/1, 1/2 and 1/3. The ILO MMIC abilities for synthesizer applications were confirmed with an injection-locking time of only 100-200 nsec, which is less than 1/100 that of PLL oscillators, and also with free-running oscillation performance and a wide injection locking range within a temperature range of -30 and 80.

We propose an axially symmetrical Fabry-Perot multiple-device oscillator operating at an axially symmetrical TEM01n-mode, which has an excellent feature of uniform device-field coupling required for high efficiency power combining. By carrying out the boundary element analysis, it is shown that a plane-mirror output structure is remarkably advantageous compared with a concave-mirror output structure to obtain an adequate output coupling and to enable stable operation characteristic with respect to the axial mode number n. Experiments in X-band confirmed this excellent performance and achieved almost perfect power combining of efficiency as high as 106% and 99% for six- and eight-device case, respectively.

This paper discusses advanced wireless communication technologies for achieving future high-speed mobile radios. Mainly, five technical fields are considered, that is, multi-level modulation for transmitting high-capacity information signal, advanced adaptive wireless system flexibly changing modulation level, symbol rate and traffic according to fading conditions, adaptive multicarrier system transmitting multimedia signals by changing the number of carrier according to the capacity of the signals, new CDMA techniques for mapping different bit rate services onto the same allocated bandwidth at the same time, and optical-linked microcellular communication system with millimeter wave air interface.

In this paper we will propose a deterministic approach to model the radio propagation channels complex indoor environments. This technique applies the SBR method to find equivalent sources (images) in each launched ray tube, and sums the receiving amplitude contributed by all images coherently. We verify our SBR/image approach by comparing the numerical results in two canonical examples where closed-form solutions exist. The good agreement indicates that our method can provide a good approximation of high frequency radio propagation inside corridors where reflection is dominant. In the special case of a curved corridor, which can not be solved by analytic methods, we find a "focusing" effect that at some certain point the receiver will receive high power, even though it is out of sight. This SBR/image method can be enhanced by including the wall penetration and wedge diffraction effects, and even more complicated indoor environments will be tackles in the near future.

This paper presents a theoretically best algorithm within the framework of our image noise model for reconstructing 3-D from two views when all the feature points are on a planar surface. Pointing out that statistical bias is introduced if the least-squares scheme is used in the presence of image noise, we propose a scheme called renormalization, which automatically removes statistical bias. We also present an optimal correction scheme for canceling the effect of image noise in individual feature points. Finally, we show numerical simulation and confirm the effectiveness of our method.

A computer-based system for the automatic determination of the physical parameters of rainfall was developed. The measuring device consists of a light source and two TV cameras. Images of raindrops that fell through the slit were observed on a frosted glass plate as shadow images which were photographed simultaneously by two TV cameras with different shutter speeds and analyzed. The data indicated that the shape of raindrops were spheroid in case of small diameter but were slightly deformed into an oblate spheroid in case of larger diameter, and the fall velocity tends to increase with increasing size of raindrops. Rainfall rates calculated from the shape and velocity were compared with those measured directly and found to agree.

The electroretinogram (ERG) is used to diagnose many kinds of eye diseases. Our final purpose in this paper is a detection of diabetic retinopathy by using only ERG. In this paper, we describe a method to examine whether presented ERG data belong to a group of diabetic retinopathy. The ERG mainly consists of the a-wave, the b-wave and the oscillatory potential (op-wave). It was known that the op-wave varies as progress of retinopathy. Thus, we use the latency, the amplitude and the peak frequency of the op-wave. First, we study these features of sample ERG data, statistically. It was clarified that some of these characteristics are significantly different between a normal group and a group of diabetic retinopathy. By using some of these characteristics, we classify unknown ERG data on the basis of the Mahalanobis' generalized distance or the linear discriminant function. The highest accuracy of this method for the unknown data is about 92.73%.

In case of object recognition using 3-D configuration data, the scale and poses of the object are important factors. If they are not known, we can not compare the object with the models in the database. Hence we propose a strategy for object recognition independently of its scale and poses, which is based on Hopfield neural network. And we also propose a strategy for estimation of the camera motion to reconstruct 3-D configuration of the object. In this strategy, the camera motion is estimated only with the sequential images taken by a moving camera. Consequently, the 3-D configuration of the object is reconstructed only with the sequential images. And we adopt the multiple regression analysis for estimation of the camera motion parameters so as to reduce the errors of them.

This paper presents a system for recognition of on-line cursive Hangul (Korean characters) by means of DP matching of structural information. The penalty function has the following special features. In order to prevent short spurious strokes from causing large penalties, an input stroke is weighted by its length relative to other input strokes. In order to make use of pen-up and pen-down information, a penalty is incurred when 2 strokes of differing type (i.e. pen-up with pen-down) are matched. Finally, to reduce the chance of obtaining a suboptimal solution which can result from using the greedy algorithm in DP matching, we look-ahead an extra match. In a computer simulation we obtained a recognition rate of 92% for partially cursive characters and 89% for fully cursive characters. Furthermore, for both cases combined the correct character appears 98% of the time in the top 10 candidates. Thus we confirmed that the proposed algorithm is effective in recognizing cursive Hangul.

An adaptive digital filter with adaptive sampling phase is proposed. The structure of the filter makes use of an adaptive delay device at the input of the filter. The algorithm is derived to determine the value of the delay and the filter coefficients by minimizing MSE (mean square error) between the desired signal and the filter output. The computer simulation of the convergence of the proposed adaptive filter with the input of sinusoidal wave and BPSK modulated wave are shown. According to the simulation, the MSE of the proposed adaptive delay algorithm is lower than that of the conventional LMS algorithm.

In this letter, we introduce a predictor based least square (PLS) algorithm. By involving both order- and time-update recursions, the PLS algorithm is found to have a more stable performance compared with the stable version (Version II) of the RLS algorithm shown in Ref.[1]. Nevertheless, the computational requirement is about 50% of that of the RLS algorithm. As an application, the PLS algorithm can be applied to the fast Newton transversal filters (FNTF). The FNTF algorithms suffer from the numerical instability problem if the quantities used for extending the gain vector are computed by using the fast RLS algorithms. By combing the PLS and the FNTF algorithms, we obtain a much more stable performance and a simple algorithm formulation.

An error correction/detection decoding scheme of binary Hamming codes is proposed. Error correction is performed by algebraic decoding and then error detection is performed by simple likelihood ratio testing. The proposed scheme reduces the probability of undetected decoding error in comparison with conventional error correction scheme and increases throughjput in comparison with conventional error detection scheme.

Low-power circuit techniques for size-configurable SRAM macrocells with wide range of operating frequency are presented. Synchronous specification is employed to drastically reduce the power dissipation for low-frequency applications. Dynamic circuits applied to bitliness and sense circuits contribute to the reduction of power dissipation. To enhance the high-end limitation of operating frequency, a latch-type fast sense circuit and an accurate activation-timing control technique for size-configurable memory macrocells are proposed, and a special CMOS-level input buffer is devised to enable the minimum cycle time of fast synchronous memory macrocells to be evaluated with conventional LSI-test systems. A memory macrocell using these techniques was fabricated with 0.5-µm CMOS technology. Its power consumption strongly depends on the operating frequency, and at 3-MHz suitable for codeless telephone applications is less than 5% that of an asynchronous SRAM designed with full-static CMOS circuits. Its maximum operating frequency at 3.3-V in 100-MHz.

An optimum design scheme for logical network topologies on a Flexible Multi-QoS Logical ATM Network, named Full-Net, is proposed. Full-Net offers high-quality Virtual-Path (VP) networks and controls end-to-end QoS only at the VP-network's access points. To develop the optimum network topology for multimedia traffic in a single ATM network, a logically con figured Virtual Channel Handler (VCH) interconnection network is associated with each QoS class. Many logical networks can be mapped at the same time on the same network, because mapping is independent of the network's physical implementation. To achieve an optimum design scheme for logical networks, the number of disjoint routes is introduced as the parameter used to optimize logical network topology. The number of disjoint routes is chosen so as to maximize total network efficiency. The optimum number of disjoint routes depends on the required QoS, VC-traffic characteristics, and traffic demand. By choosing the relevant cost characteristics, the network operator can easily maximize network efficiency and provide customers with the QoS they request at minimum cost. The proposed optimum multi-QoS network design scheme on a Full-Net architecture is an efficient solution to implementing multi-QoS control in an ATM network.

At the beginning of the 21st century, 1 Gb DRAMs will be in practical use, and sufficient in terms of memory capacity for most memory applications systems. The key technologies for multimedia systems include data compression, communication, storage, and human interfaces. Image data processing, ATM switch, and microprocessor in multimedia applications require the high data transfer rate from several 100 Mbits/s to Tbits/s. Storage systems, on the other hand, require the reduction of the price per bit to less than 10 cents/Mbytes. Application specific design approaches towards a system-on-chip are strongly needed for ULSI memories in the multimedia era.

Programming and program-verification methods for low-voltage flash memories using the Fowler-Nordheim tunneling mechanism for both programming and erasure are described. In these memories, a great many memory cells on a selected word line, such as 512-bytes worth of cells, are programmed at the same time for high-speed programming. The bit-by-bit programming/verification method can precisely control threshold-voltage deviation of programmed memory cells on the selected word line for low voltage operation. By using an internal program-end detection circuit, the completion of program mode can be checked for in one clock cycle, without reading out 512-bytes of data from the memory chip to the external controller. Moreover, the variable pulse-width programming method reduces the total number of verifications.

We developed an on-chip memory tester macro using a microprogram ROM BIST circuit. Only slight modification of address buffers, data bus I/O circuits and control clock generators of the memory core circuits was required to implement this BIST macro. We fabricated a 1 Mb DRAM with the BIST, and experimental results showed that the measured shmoo plot of VCC versus the cycle time by the BIST closely agreed with that of a memory tester. Disagreement was caused by test address signal set-up time delay and VOH/VOL differences in both test conditions. The BIST macro will be especially useful for design-for-testability of embedded memories.