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.

Cellular automata (CA) implementations are expected as potential test-pattern generators (TPGs) for Built-In Self-Testing of VLSI circuits, in which highly random parallel patterns ought to be generated with simple hardware. Objective here is to design one-dimensional, binary, and linear CA implementations with cyclic boundary conditions that can operate on maximum length of period. To provide maximum period of operations, it is necessary to bring some irregularities into the configurations. It is also expected for TPGs to make maximum or sufficiently long period of operations to prevent re-initialization. Our approach is to generate transition matrices based on fast parallel implementations of LFSRs which have trinomials as characteristic polynomials and then to modify the diagonal components. Some notable properties of diagonal vectors were observed.

We have studied the basic optical and physical characteristics of polymeric optical waveguide films with S-shaped waveguides and 45 mirrors applied as multimode optical interconnection components. The core and cladding of the waveguide films were made of deuterated-polymethylmethacrylate (d-PMMA) and UV-cured resin, respectively. We evaluated the insertion losses of the waveguides, the crosstalk and the 45-mirror losses in these waveguide films and demonstrated that they have low propagation loss. The shrinkage and thermal expansion of the polymeric optical waveguide films are also discussed because of the interest in improving module packaging.

MTDMA (Multimedia, Multimode TDMA) system has been developed for the 3rd generation mobile communications. An adaptive modulation technique is employed, which select 16 QAM or QPSK modulations fit for the O (Indoor Office)/P (Outdoor to Indoor and Pedestrian) communication environments. The maximum user rate of 4 Mbps is realized. Basic specification is described for O, P and V environments.

Performance of optical asynchronous code-division multiple-access (CDMA) systems with double optical hard-limiters is analyzed in the presence of avalanche photodiode (APD) noise and thermal noise. Optical orthogonal codes (OOC's) are employed as signature sequence codes. In the analysis, chips are assumed to be synchronous among users: the chip synchronous case. Thus, the performance results in the upper bound on the performance of the asynchronous system. The results show that the optical asynchronous CDMA systems with double optical hard-limiters have good performance in the presence of the APD noise and the thermal noise even when the number of simultaneous users is large.

The next generation mobile communications systems must support multimedia communications services as well as conventional voice service. DS-CDMA is regarded as the most promising candidate, because it is indispensable to cope with multimedia. The system capacity of DS-CDMA system is limited by the total interference level. As a result, in DS-CDMA systems many users suffer very poor communication quality if the total interference level exceeds this limit. Therefore, this paper considers smoothing interference fluctuation using the difference between voice and data in a type of QoS (quality of service). In other words, voice communication is suitable for a loss system because the quality of voice communication is delay-sensitive. On the other hand, data communication is suitable for a waiting system because the quality of data communication is non-delay-sensitive. This paper focuses on a system that applies a circuit switching method for voice traffic and a reservation type packet switching method for data traffic and proposes a data traffic control method. In this proposed data traffic control method, a base station controls data transmission from a mobile station to utilize unused voice traffic resources. As a result, the proposed method achieves highly efficient use of the radio spectra by smoothing interference fluctuation in DS-CDMA systems. This paper evaluates the performance level of the proposed method from a system capacity standpoint. It is shown that the proposed method achieves higher system capacity in voice/data integrated transmission.

A communication system which attains an efficient amalgamation of base station (BS) type cellular communication and non-BS type direct communication for mobile terminals (MTs), "cellularad-hoc united communication system," is proposed. In this system, whether a cellular system or an ad-hoc communication system is chosen by distance and whether the condition is good or not between communicating MTs. In other words, when two terminals are relatively near each other and are in sufficient conditions to communicate directly, they select the ad-hoc communication, while for other cases they use the cellular system. The proposed system was confirmed to have effective channel usage and low battery consumption from the simulation results. It can be also said that this system is suited especially for MTs which tend to communicate with closer partners such as operational mobile robots and autonomous carrier vehicles.

A RAKE combiner based on a matched filter (MF) can be relatively easily implemented since the despread signal components that have propagated along different paths appear sequentially at the MF output. An important design problem is how to accurately select the paths having sufficiently large signal-to-noise power ratios (SNRs). This paper proposes a simple path selection algorithm that uses two selection thresholds. The first threshold is to select the paths that provide largest SNRs. However, as the total received signal power (sum of the signal powers of all paths) decreases, some of the selected paths become noisy. Therefore, we introduce a second threshold that discards the noisy or noise-only paths from among those selected by the first threshold. We apply the proposed path selection algorithm to a pilot symbol-assisted coherent RAKE combiner and find by computer simulations a near optimum set of the two thresholds in frequency selective multipath Rayleigh fading channels. Several power delay profile shapes are considered. The simulation results demonstrate that the MF-based RAKE combiner with the two selection thresholds can achieve a bit-error-rate (BER) performance close to the ideal case (i. e. , the paths to be used for RAKE combining are selected for each power delay profile such that the required signal energy per information bit-to-noise spectrum density ratio (Eb/N0) is minimized).

To enhance the anti-fading technique of direct sequence code division multiple access (DS/CDMA) schemes in land mobile radio communication systems, a two-dimensional RAKE reception (2D-RAKE) scheme in beam space digital beam forming (BS-DBF) antenna configuration is proposed. The proposed scheme is applied to cellular base stations where the received signals in the reverse link are relieved from multipath fading by means of enhanced RAKE combining in spacial and temporal domains. Fundamental performance in the reverse link under multipath fading environments is investigated by computer simulation applying a wideband propagation channel model.

This paper presents a novel transmission diversity scheme for code division multiple access system. Conventional diversity receivers in mobile stations require space and complicated circuits, however, the proposed diversity schemes present significant diversity effect without any diversity equipment at the mobile station. It is possible to use the transmitter diversity at the base station by using the feature of time division duplex (TDD) which has strongly correlated fading patterns in both forward and reverse link. Computer simulation is performed to evaluate the performance of the proposed systems for single user environment. The performance of the system 1, which select best situated antenna, is analyzed and the BER performance for multiple access is presented.

This paper compares the BER performance of two types of pilot channel-based coherent Rake combining achievable by the use of weighted multi-slot averaging (WMSA) channel estimation filter in DS-CDMA transmission links. One is for the time-multiplexed pilot channel and the other is for the parallel pilot channel. The WMSA channel estimation filter weights and averages the received pilot over a period of several slots to improve the BER performance. We propose the WMSA channel estimation filters for time-multiplexed pilot and parallel pilot structures. Achievable BER performance under frequency-selective fading environments is computer simulated. The simulation results show that almost same BER performance can be achieved for both pilot channel structures when the same energy is allocated to the pilot.

This paper proposes the Dual Zipfian Model addressing how to describe HTTP access trends in large-scale data communication networks, and discusses how to design the capacity of address cache tables in an edge router of the networks. We show that destination addresses of packets can be characterized by two types of Zipf's law. Fundamental concept of the Dual Zipfian Model is in complementary use of these laws, and we can derive the relationship between the number of accesses and the number of destination addresses. Experimental results show that the relation gives a good approximation. Applying this relation, we derive cache hit probabilities of the address cache table that incorporates high-speed address resolution. Using the probabilities, design issues including the capacity of the cache tables and aging algorithms of cache entries are also discussed.

The Future Public Land Mobile Telecommunication Systems (FPLMTS) standards have made it quite clear that in the near future, the capability in doing wireless data transmission will become necessary in order to make the tether-free use of multimedia applications possible. CDMA is considered the most appropriate and probable radio access method of FPLMTS for its high capacity and flexibility in accommodation of multimedia and variable rate users. In order to further increase the capacity of CDMA system, several techniques have been studied and proposed such as an interference canceller and adaptive array antenna. We propose the novel multi-user detection type interference cancellation technique named SRIC (Symbol Ranking type IC) in this paper. SRIC is very feasible for its small amount of operation compared with other multi-user detection type ICs and can be added to a base station with slight alteration according to the requirement of higher capacity. The performance of SRIC depends on the method of calculating the likelihood. We studied three methods. In order to reduce the operations, we tried to propose two more methods. We confirmed that SRIC can make the system capacity about three times greater than that of a conventional RAKE receiver. We also confirmed that SRIC can be reduce its operations very much at some sacrifice of their performance. There are nine variants of SRIC, which have a trade off between performance and amount of operation. We can choose one of them which is most fit to our requirement. The first operation of SRIC is common with that of a conventional RAKE receiver. Therefore, SRIC can be introduced to conventional systems afterwards by inserting the interference canceller block which functions replica generation, removal, and ranking between output of a RAKE receiver and FEC decoder.

For usage in fading environments, the idea of utilizing radio signal processing with software programmable devices promises greater flexibility and functionality. However, to realize these benefits very high performance DPSs and AD converters are required, especially for adaptive antennas with CDMA. One potential method of reducing the implementation complexity is to employ multicarrier (MC) modulation as it allows parallel signal processing in addition to its benefits in combating fading and ISI effects. This paper proposes a system utilizing MC DS/CDMA and a recursive adaptive array antenna processing algorithm for estimating the array response vector (array manifold) and hence the optimal weights. In order to evaluate this system performance results obtained through computer simulations are presented. The proposed MC system improves the accuracy of the direction-of-arrival (DOA) estimation of the signal by 2 degrees as compared with a single carrier system. It is also shown that the proposed adaptive array antenna algorithm for MC DS/CDMA reduces the number of iterations of the power method significantly and allows parallel processing of the adaptive algorithm.

Electrochemomechanical deformation (ECMD) of poly(o-methoxyaniline) (PoMAn) film has been studied in various acid solutions, such as Cl-, HSO4-, BF4-, and p-toluene sulfate. The magnitude of ECMD of the film depends linearly on the degree of oxidation of the film similarly to the case of polyaniline (PAn). 2. 53% of deformation ratios along the stretched direction are obtained for 30% of reduction. In contrast to that of PAn, however, the ECMDs of PoMAn do not markedly depend on the kind of anions. Transient responses of current and deformation are investigated by the potential application stepwise and the diffusion coefficient of ions in films. The results are discussed in terms of the effect of substituted methoxy group.

Experimental results of 1. 92 Mbps data transmission over a 20 MHz wideband DS-CDMA (W-CDMA) mobile radio link under frequency selective multipath fading are presented. 1. 92 Mbps data were transmitted using an orthogonal multicode transmission scheme. The combined use of antenna diversity reception, RAKE combining, and concatenated channel coding is applied to improve transmission performance. Laboratory and field experimental results demonstrated the possibility of 2 Mbps data transmission in a real fading environment.

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.

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.

The final closed-form expression of the bit error rate (BER) is presented for a DS-CDMA system using a maximal ratio combining (MRC) diversity in conjunction with simple channel coding over a Rician fading channel. The accuracy of the BER evaluated by this expression is verified through comparison with a semi-analytic simulation result. The effect of diversity order and channel coding on the bit error rate performance is also considered for typical multipath delay profiles with different Rician ratios.

The following, which is related to the design of the microwave filters, is mainly presented: (1) certain useful approximation which can be obtained by double-resistive- terminated 2-ports consisting of a cascade of two 1-variable 2-ports in different variables, and (2) an approach for filter design from 2-variable viewpoint. Approximations presented provide useful magnitude responses in 2-D domain. Hence it is discussed that how the provided 2-D responses can be used for the design of the microwave filters. Furthermore, properties of the 2-variable transfer functions resulting in such circuits are given.