We have developed a new type of phase interpolation DDS with a digitally controlled delay generator. The new DDS is similar to a sine output DDS in that it produces low spurious signals, but it does not require a sine look-up table. Periodic jitter in the MSB of the DDS accumulator is reduced with the digitally controlled delay generator. Experimental results confirm successful frequency synthesizer operation in which the spurious signal level is successfully reduced to less than that the MSB of the accumulator.

This paper proposes a scheme for synchronization of stored video and audio streams in PHS. A video stream of H. 263 is transmitted over a PHS channel with ARQ control, while an audio stream of 32 kbit/s ADPCM is sent on another channel without any control. In order to preserve the temporal constraints within the video stream as well as the relationship between the video and audio streams, we adopt a new control scheme which modifies the target output time according to the amount of video data in the receive-buffer. Through simulation we assess the characteristics of this scheme in both random and burst error environments and confirm the effectiveness of the scheme.

Non-uniform traffic can affect communications quality in microcell systems, and this disparity in communications quality between base stations (BSs) lowers the system efficiency in CDMA systems. If traffic distribution and propagation conditions are already known during the introduction of a CDMA system, it is desirable to design cell areas according to the non-uniformity of traffic distribution and BS locations. Cell area is determined by the transmission power of the pilot-signal from the BS and it is necessary to control the transmission power of mobile stations in the uplink, which is determined by the desired power level at the BS, according to the cell area. The disparity in communications quality can be rectified by optimally designing the two parameters of the pilot-signal power and desired power level. This paper describes an algorithm for setting both the pilot-signal power and the desired power level during the cell design stage in CDMA systems. The proposed algorithm operates that the communications qualities of all BSs in the system converge to average quality by adjusting the two parameters. The parameters of all BSs in the whole system can be determined through computer calculation. Through performance evaluations, we confirmed that the average SIRs of all BSs attained almost the same value and the variance between the BSs was less than half by adopting the cell design algorithm when there was dispersion in BS placement. This algorithm is also effective using the actual measured SIR after a system has been established.

We have improved the optical beam induced resistance change (OBIRCH) system so as to detect (1) a current path as small as 10-50 µA from the rear side of a chip, (2) current paths in silicide lines as narrow as 0. 2 µm, (3) high-resistance Ti-depleted polysilicon regions in 0. 2 µm wide silicide lines, and (4) high-resistance amorphous thin layers as thin as a few nanometers at the bottoms of vias. All detections were possible even in observation areas as wide as 5 mm 5 mm. The physical causes of these detections were characterized by focused ion beam and transmission electron microscopy.

In this paper, we propose several novel methods to decrease propagation error for multiple access interference cancellation techniques in asynchronous DS/CDMA. To increase spectral efficiency, the system wherein transmitting signal power of each user is assigned with exponential law and multiple access interference successive cancellation is used in the receiver has been discussed. However, when the number of active users is increased, propagation error occurs in the receiver. Thus, the improvement effect of spectral efficiency in the system has been degraded. In this paper, we propose novel methods to decrease these propagation errors for the system. These novel methods are quasi-maximum likelihood method that means maximum likelihood in considering the signal of the next user when the signal of the arbitrary user is demodulated, feedback method that means the demodulation error of the stronger users in transmitting signal power is estimated after several users, demodulations and the error is corrected, and combination method that is a combination of quasi-maximum likelihood method and feedback method. And we evaluate their performances by computer simulation and show that the combination method is effective for the reduction of the propagation error.

This paper proposes an adaptive permission probability control method for the CDMA/PRMA access protocol. The proposed method is effective to the uplink channels of the integrated voice and data wireless system. The proposed method uses the R-ALOHA protocol with end-of-use flags in order to avoid the reservation cancellations caused by excessive multiple-access interference. Also, a higher priority at packet transmission is given to voice compared with data so that the real-time transmission of voice packets can be guaranteed. Priority is controlled by suitably varying permission probabilities. Permission probabilities are adaptively calculated according to both the channel load and the channel capacities. The usefulness of this proposed method is ensured through computer simulation in an isolated cell environment. Moreover, various applications to cellular environments are investigated. The calculated results indicate that transmission efficiency has been improved compared with the conventional CDMA/PRMA protocol.

Two types of CPW-fed active antenna for television receivers, printed on thin dielectric film, are analyzed numerically and experimentally and their broadband operations are reported. The actual gain of the receiving active antenna is expressed in terms of the transducer power gain of the amplifier circuit and the effective length of the passive antenna. Between the feed point of the passive antenna element and the CPW, the silicon transistor 2SC2585 or 2SC3604 is integrated with a dipole antenna or loop antenna. The actual gains of a dipole antenna with 24 cm length are more than 8 dBd (relative gain to the standard half-wave dipole) at frequencies from 470 to 770 MHz for television channels 13-62 in Japan. In the case of a loop antenna with a size of 25. 8 cm12 cm, actual gains of more than 3. 5 dBd are obtained for channels 1-12, from 90 to 222 MHz, and more than 6. 5 dBd for channels 13-62, from 470 to 770 MHz.

Since the development of odor sensing system is required in many fields, we have been developing the system using QCM (Quartz Crystal Microbalance, 10 MHz AT-cut) array and neural-network pattern recognition. Since it is important to obtain stable sensor responses, a sensing film of lipid blended with PVC (polyvinyl chloride) was studied here. First, we studied the stability of various sensing films e. g. , phospholipids, GC liquid stationary phase materials and others in odor sensing system. It was found that most of lipids were stable, while PEG 200, octadecane and DBP were not stable materials. Second, we studied to obtain a stable QCM sensor using a sensing film blended with PVC. 4 plasticizers blended with PVC were systematically characterized, analyzing the pattern of QCM sensor responses by multivariate analysis. It was found that the pattern of DOPP was very different from that of PVC. Thus, we adopted DOPP as plasticizer and the stable sensor response was obtained using a lipid film blended with both PVC and DOPP. Finally, we studied the influence of sensing film materials on the stability of QCM sensors. It was found that the loss of sensing film mass after many vapor exposures depended upon the molecular weight.

In this paper, we propose a novel power distribution method which can be adopted in case of the nonuniform distribution for mobiles in DS/CDMA distributed power cellular system. DS/SS distributed power cellular system has been proposed for achieving RAKE reception in micro-cellular environment. In forward link of this system, optimum power distribution method which can minimize the required total transmitting power has been discussed. The performance of this system has been shown in case of the uniform distribution for mobiles. In this paper, first, we propose a novel method in case of the nonuniform distribution. In the proposed method, replacing the path and its combinations of signals from base stations successively, we can find a new condition of less power distribution which is passed over in a conventional distribution method. We adopt simple distribution models for mobiles and compare the proposed method with the other methods by computing the total transmitting power and the quantity of calculations. As a result, we show that it is possible to almost obtain optimum power distribution by using the proposed method. Next, we adopt a nonuniform distribution model, in which the difference of the number of users exists only in the center cell. Using this model, we compare the proposed method with the other methods by computing the total transmitting power, the quantity of calculations, and a probability of impossible power distribution. Finally, in order to simplify and decrease the quantity of calculations of the proposed method, we propose a modified calculation algorithm which is applicable in case of that a new mobile station has increased. And we show the performance of this algorithm.

For mobile telecommunication systems, it is important to accurately predict the propagation-path loss in terms of the estimation of the radiowave coverage area. The propagation-path loss has been estimated in a median obtained spatially from many received amplitudes (envelopes) within a region of several tens times as long as the wavelength, rather than in the envelopes themselves. Although ray tracing can obtain the envelopes and their median that reflect the site-dependent characteristics, the estimated median sometimes does not agree with the measured one. Therefore, the accuracy improvement has been expected. In this paper, an accuracy improvement is achieved by substituting a median with random phases for the median obtained spatially from many envelopes. The characteristic function method is used to obtain the cumulative distribution function and the median analytically where the phases are randomized. In a multipath environment, the phase-estimation error accompanying the location error of the ray tracing input influences the spatially obtained median. The phase-randomizing operation reduces the effects of the phase-estimation error on the median prediction. According to our estimation, improvements in accuracy of 4. 9 dB for the maximum prediction error and 2. 9 dB for the RMS prediction error were achieved. In addition, a probability-based cell-design method that takes the radiowave arrival probability and the interference probability into consideration is possible by using the percentiles obtained by the characteristic function method and the cell-design examples are shown in this paper.

This paper newly proposes the CMT/IM/DD system for universal radio access networks where radio base stations (RBSs) and an optic backbone network are universally available among different radio services and providers. In the proposed system, the Chirp Fourier transformer at an RBS, converts the received FDM multiple radio service signals into optical TDM format signals, then transfers them over the optic fiber-link. This paper is focused on the discussion about the performance on the up-link of the CMT/IM/DD system. A new type of the configuration of CMT and the direct demodulation for the CMT signal are also proposed, and the SNR considering inter-symbol and inter-channel interferences caused by the CMT is theoretically analyzed. Analysis results show that the overall SNR performance of the CMT system is superior to the conventional SCM system when the number of radio channels is more than 26.

We have developed a new autofocus method using image processing techniques. This method consists of two steps. The first step is the preset of an objective lens condition with the aid of the feedback of Z-sensor. Next, a hole pattern to be measured is detected using the pattern recognition. In the second step, the E-beam is shifted to the center of a hole pattern and scanned across the axis of a pattern. The exciting current of the objective lens is changed at constant intervals, where the center position of the range is the preset value of the Z-sensor. The best focus condition is determined based on the signal profile obtained by the autofocus scan. The measurement repeatability (3σ) can be achieved within 3. 9 nm. The percentage of success of 98. 7% can be realized in the present autofocus method.

A series of transparent photochemical acid-generators (PAGs) has been successfully prepared and investigated to apply ArF excimer-laser lithography. These PAGs were synthesized as new alkylsulfonium salts that have cycloalkyl groups but no aromatic ones. They were almost transparent at 193. 4 nm and have high acid-generation efficiency enough to use for ArF excimer-laser resists. The photochemical reaction of these alkylsulfonium salts occurs mainly due to the S-C bond fission. A resist utilizing the PAGs was capable to resolve a 0. 2µm L/S pattern at a 50-mJ/cm2 dose with an aqueous alkaline developer. These PAGs are promising materials for use in ArF excimer-laser lithography.

Variable-rate data transmission with no rate indicator is described for direct sequence code division multiple access (DS-CDMA) mobile radio. The variable-rate data to be transmitted is block-encoded using a cyclic redundancy check (CRC) and then convolutionally encoded before being spread. The convolutionally encoded data is always brought to the zero state at the end of the data sequence within each frame. Blind rate detection is incorporated into the process of Viterbi-decoding the received convolutional-coded frame data. At each possible end bit position (i. e. , each possible transmission rate), the trellis path arriving at the zero-state is selected if its path metric satisfies a certain condition, and is then traced back to recover the frame data. CRC is used to determine whether the recovered data is correct or not. The path selection condition is described. The average frame error rate (FER) and average false detection rate (FDR) are evaluated by computer simulation under frequency selective multipath Rayleigh fading environments and the results are compared with another variable-rate transmission scheme using a rate indicator.

A new radar system is presented, which consists of one main radar and cooperative plural transponders. The transponders are integrated in the respective retrodirective antennas which are arranged beyond the horizon in such a manner as they surround the main radar. An algorithm for determining the three-dimensional target position is given. Computer simulations have been made for different target positions by assuming measurement errors. A target whose monostatic radar cross section is small or has been specially reduced by absorbing materials could be detected by this system if it is properly constructed.

Radio transmission technologies for IMT-2000 are being studied and standardized all over the world. Several national/regional standardization bodies are developing proposals on radio transmission technologies to meet the cut off date of June 30, 1998 set by ITU. This paper shows necessity to develop and standardize IMT-2000 in Japan, principle attitude on IMT-2000 standardization, selection process of W-CDMA, and the current situation of study on IMT-2000 in ARIB (Association of Radio Industries and Businesses).

This paper proposes a multiple QoS control scheme that combines the head-of-line priority (HOLP) discipline with equivalent-window connection admission control (CAC). The proposed scheme can support the different cell loss ratios of both delay-sensitive traffic in high-priority buffers and delay-tolerant traffic in low-priority buffers. The CAC scheme extends a measurement-based CAC algorithm for a single buffer to the low-priority buffer with the HOLP discipline to provide the cell loss ratio objective. We introduce an equivalent window for monitoring low-priority cell streams. The equivalent window size equals the period within which the number of times the low-priority buffer is scanned to read cells is constant. Thus the equivalent window size varies with the high-priority queueing state. Numerical results indicate that the proposed QoS control scheme using the equivalent-window CAC can utilize network resources more effectively than the conventional control scheme which is Virtual Path (VP) separation for different cell loss requirement services. In addition, it is confirmed that the proposed scheme provides conservative admissible loads. Thus, this proposed scheme can achieve large statistical gains while providing both high-priority and low-priority cell loss ratio objectives. The proposed scheme will be very useful for cost-effective multimedia services that have different QoS requirements.

We previously proposed a next generation cellular system for IMT-2000 based on the Wideband DS-CDMA with TDD scheme (W-CDMA/TDD) and have evaluated its performance by computer simulation, laboratory and field experiment. With the W-CDMA/TDD, because of its correlation between the downlink and the uplink, transmission and reception space diversity (SD) at a base station and open-loop transmit power control (TPC) can be simply realized. This paper reports performance of laboratory and field experiments using a developed testbed. The results shows it has been confirmed that transmission and reception SD and open-loop TPC have sufficient performance under a field environment as well as laboratory environment.

Personal communication systems are increasingly required to accommodate not only voice traffic, but also various types of data traffic. Generally speaking, voice traffic is symmetric between uplink and downlink, while data traffic can be highly asymmetric. It is therefore inefficient to accommodate data in a conventional TDMA/TDD system with fixed TDD boundary. In this paper, focusing on the continuous data traffic which requires multi-slots in a circuit based TDMA/TDD system, an algorithm is proposed in which the TDD boundary are moved adaptively to accommodate data traffic efficiently. Comparing with the boundary-fixed conventional algorithm, computer simulations confirm that the proposed algorithm has superior performance in the excessive transmission delay of data while maintaining the performance of voice. The intercell interference between mobiles due to different TDD boundaries is also confirmed to be negligible. Moreover, almost the similar performance improvements of the proposed algorithm are confirmed for two different average message sizes of data calls.

A single-chip GaAs Transmit/Receive (T/R)-MMIC front-end has been developed which is applicable to 1. 9-GHz personal communication terminals such as digital cordless phones. This chip is fabricated using a planar self-aligned gate FET useful for low-cost and high-volume production. The chip integrates RF front-end analog circuits a power amplifier, a T/R-switch, and a low-noise amplifier. Additionally integrated are a newly developed voltage-doubler negative-voltage generator (VDNVG) and a control logic circuit to control transmit and receive functions, enabling both a single-voltage operation and an enhanced power handling capability of the switch, even under a single low-voltage supply condition of 2 V. The power amplifier incorporated onto the chip is capable of delivering a 21 dBm output power at a 39% efficiency, and a 30 dB associated gain with a 2 V single power supply in the transmit mode. The gain and efficiency are higher than those of the previously reported amplifier operating with a 2 V single power supply. The VDNVG produces a step-up voltage of 2. 9 V as well as a negative voltage of -1. 8 V from a 2 V power supply, operating with a charge time of less than 0. 25 µs. The control logic circuit on the chip has a newly designed interface circuit utilizing the step-up voltage and negative voltage, thereby enabling the chip to handle high power outputs over 24 dBm with a low operating voltage of 2 V. In the receive mode, a 1. 7 dB noise figure and a 0. 6 dB insertion loss are achieved with a current dissipation of 3. 6 mA. The developed MMIC, which is the first reported 2 V single-voltage operation T/R-MMIC front-end, is expected to contribute to the size and weight reductions in personal communication terminals.