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.

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 a bit-stream-arranged weighted modulation scheme to improve voice quality in low delay spread frequency selective fading channels. The proposed modulation scheme employs an input bit stream arrangement method that changes the bit stream order for significant bits so that they are not adjacent to each other over time; a mapping method that controls the amplitude of the modulation signals according to the importance of the bits; and modified differential encoding to prevent the error propagation from insignificant to significant bits. Computer simulations clarify that the proposed bit-stream-arranged weighted modulation scheme shows a S/N improvement of 8 dB in an 8-bit linear pulse code modulation (PCM) voice signal compared with the conventional non-weighted π/4-shift quadrature phase shift keying (QPSK) modulation scheme. The proposed scheme also shows 3. 5 dB improvement in a 4-bit adaptive differential pulse code modulation (ADPCM) voice signal. In this case, occurence of 'click noise' in recovered voice signal is halved. Although the proposed scheme increases the peak power of the modulated signals, the non-linearity of the power amplifier is not fatal.

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.

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.

An efficient algorithm is proposed for finding all solutions of bipolar transistor circuits. This algorithm is based on a simple test that checks the nonexistence of a solution using linear programming. In this test, right-angled triangles are used for surrounding exponential functions of the Ebers-Moll model, by which the number of inequality constraints decreases and the test becomes efficient and powerful.

We demonstrate that the frequency modulated video signals in the subcarrier multiple access optical network can be satisfactorily transmitted using our proposed method, that broadens an optical spectrum by multiplying the subcarrier signals by an additional signal and that reduces optical beat interference, even if the wavelengths of four Fabry-Perot laser diodes are very close each other.

The increasing activity at millimeter wave frequency band and the growing demand for waveguide components to be applied for integrated circuit purpose have promoted the need for applying the field-theory-based approaches to the design procedure. In this paper, genetic algorithms (GA's) are applied to accurately design the iris-coupled waveguide filters based on network-boundary element method (NBEM). GA's model the natural selection and evolve towards the global optimum, thus avoid being trapped in local minima. Network-boundary element method, which combines boundary element method with network analysis method, derives the network parameters of the guided wave structures with less storage location and central processing unit time. Therefore, NBEM is a feasible and efficient field-theory-based approach for the GA optimization of waveguide filters. With NBEM performing the task of evaluating the performance of the filter designs optimized by the GA, rigorous and optimal designs of the waveguide filters are realized. The obtained analysis and optimization results are compared to a number of reference solutions to demonstrate the validity and accuracy of the proposed approach.

This paper describes an efficient method to simulate lossy coupled transmission lines based on the delay evaluation technique. First, we review the previous methods, and refer to several problems concerned with these methods. Next, a novel waveform relaxation-based simulation method is proposed, which uses the delay evaluation technique. This method enables to obtain the accurate transient waveforms using smaller number of moments than the other moment methods use, and is modified for acceleration by the generalized line delay window partitioning (GLDW) technique. Finally, this method is implemented in the waveform relaxation-based circuit simulator DESIRE3T+, and the performance is estimated.

This paper proposes a novel bidirectional rod antenna (BIRA) comprising a collinear antenna and parasitic wires as a base station antenna for a street microcell. The spacing between the collinear antenna and the parasitic wire, and the length of the parasitic wires, which are the design parameters obtaining a bidirectional pattern, are investigated using the moment method. The results show that wide spacing enlarges the bandwidth obtaining the bidirectional pattern, however it decreases the gain. Furthermore, to enlarge the bandwidth, a BIRA with arc parasitic plates whose radius is the same as that of the radome is also proposed. The configuration can be constructed using the same exterior as the BIRA with parasitic wires. It is also shown that the arc parasitic plates enlarge the bandwidth in proportion to the area projected onto the tangential plane at the center of the arc. Finally, a prototype of the proposed antenna is shown.

Error performance as well as ATM cell transfer characteristics in a new category of wireless access systems is discussed. Relocatable wireless access with neutral feature between the fixed and mobile systems can convey Mbit/s-order capacity with fairly high quality under line-of-sight propagation. It is an important question for such wireless access systems whether they are able to form a part of wired networks satisfying performance objectives specified in ITU-T Recommendations. This paper analyzes the characteristics of relocatable systems under Gamma-distribution fading environments, and clarifies quantitative relations between Bit Error Rate (BER), Severely Errored Second (SES), Errored Second (ES) and Cell Loss Ratio (CLR) in a calculation model employing QPSK and typical HEC (Header Error Control). Thus it is demonstrated for the first time that in most cases the dominant parameter is the SES objective. Also it will be possible for a relocatable system with appropriate fade margin to meet the ITU-T performance specifications.

It is important to know phase offsets of a binary code in the field of mobile communications because different phase offsets of the same code are used to distinguish signals received at a mobile station from those of different base stations. When the period of the code is not very long, the relative phase offset between the code and its shifted code can be found by counting the number of bits delayed from the code of the same bit streams. But as the period of the code increases, it becomes difficult to find the phase offset. This paper proposes a new method to calculate the phase offset of a binary code. We define an accumulator function, which is used to calculate the phase offsets between the code and its shifted code. Also the properties of the accumulator function are investigated. This number theoretical approach and its results show that this method is very easy for the phase offset calculation. Its application to the code division multiple access (CDMA) system to define a reference code is given. The simple circuit realization of the accumulator function to calculate the phase offset between the received code and receiver stored replica code is described.

This paper describes the evaluation of the Voltage Down Converter (VDC) with low ratio of consuming current to load current in DC/AC operation mode. The stability, response and power consumption are investigated. First, for the stability and response, the VDC can operate in the condition that the bounce of the down voltage (dVDL) is no more than 10% of the setting voltage and the maximum load operation frequency (fmax) is 100 MHz at the average load current 70 mA (the maximum load current 140 mA). Secondly, for the power consumption, by using this VDC technology, the value of IC/IL can be suppressed to 5.1E-4 (IC: total consuming current in VDC, IL: average load current) in the condition that dVDL is no more than 10% of the setting voltage and fmax is 10 MHz at the average load current 70 mA. Thus, it is made clear that the VDC can realize high stability, good response and low power consumption at the same time. This technology is suitable for high performance ULSIs which require large load current and low-power consumption.

In this paper, we propose a new cooperative search algorithm based on pheromone communication for solving the Vehicle Routing Problems. In this algorithm, multi-agents can partition the problem cooperatively and search partial solutions independently using pheromone communication, which mimics the communication method of real ants. Through some computer experiments the cooperative search of multi-agents is confirmed.

This paper describes a new high resolution algorithm for the two-dimensional (2-D) frequency estimation problem, which, in particular, is noise insensitive in view of the fact that in many practical applications the contaminated noise may not be white noise. For this purpose, the approach is set in the context of higher-order statistics (HOS), which has demonstrated to be an effective approach under a colored noise environment. The algorithm begins with the consideration of the fourth-order moments of the available 2-D data. Two auxiliary matrices, constituted by a novel stacking of the diagonal slice of the computed fourth-order moments, are then introduced and through which the two frequency components can be precisely determined, respectively, via matrix factorizations along with the subspace rotational invariance (SRI) technique. Simulation results are also provided to verify the proposed algorithm.

This paper describes new IC design concepts using flip-chip bonding technologies for microwave and millimeter-wave circuit integration. Two types of bonding technologies, stud bump bonding (SBB) and micro bump bonding (MBB) are introduced, and their applications to microwave and millimeter-wave ICs are presented. Receiver front-end hybrid IC (HIC) for cellular and PHS handsets using SBB and new millimeter-wave ICs on Si substrate called millimeter flip-chip IC (MFIC) using MBB have been designed and fabricated to prove their advantages. These flip-chip bonding technologies are experimentally proven to provide excellent solutions for high performance and compact-sized ICs with low-cost. The HIC concept is applicable consistently over a wide range of devices from RF/microwave to millimeter-wave region.

This paper describes new millimeter-wave ICs based on flip-chip bonding using micro bumps on a low cost silicon substrate, named millimeter-wave flip-chip ICs (MFICs). They have significant advantages such as good performance, low cost and excellent flexibility in the active device selection which makes them superior to conventional monolithic microwave integrated circuits (MMICs). In order to demonstrate these advantages, a K-band front-end block for a broadband wireless communication equipment was designed and fabricated. This front-end block consists of four MFIC chips: a low noise amplifier (LNA), a down converter and two medium power amplifiers. These chips are designed to satisfy stable operation conditions using a simplified model derived for micro bump bonding (MBB). In experimental measurements; the LNA using heterojunction field-effect transistors (HFETs) had an 18 dB gain, the down converter using an HFET had a 9. 5 dB conversion loss, and two power amplifiers using heterojunction bipolar transistors (HBTs) had saturated powers of 13. 0 dBm and 11. 7 dBm, respectively. The performance for each of the developed ICs agreed with the designed values, and satisfied circuit requirements. These results show that the MFIC technique is a potential technology for manufacturing multi-functional millimeter-wave ICs.

Highly miniaturization technology in front-end GaAs Hybrid IC for mobile communication equipment will be presented. A combination of MBB (micro bump bonding) technology and the new GaAs IC fabrication process using high dielectric constant (εr) thin film technology has achieved a super small HIC with low cost and low power consumption. The new HIC was constructed of only a ceramic substrate in which the spiral inductors were formed on it and the GaAs IC chip that was bonded by using MBB technology. The MBB technology lead the HIC to a lower temperature process without soldering, a smaller bump diameter, at shorter intervals and the lowest parasitic in the bump. The advantage of the small bonding pad of the IC contributes to miniaturize the IC chip and reduces the chip cost. The GaAs IC process technology using high-εr thin film achieves the integration of all capacitors in the IC without increasing the chip size. Furthermore, low power consumption was achieved by 0. 5-µm LDD BP-MESFET with a high k-value. Although capacitors were integrated on the IC, all of the inductors were formed on the top of the ceramic substrate using a thin film metal process. This was used due to its large occupation area when it was integrated on the IC, and produced a low Q-factor. As a results, the chip was minimized to a size of 0. 81. 0 mm2 and achieved a low-cost chip. Two types of HICs were fabricated for 880 MHz cellular band and 1. 9 GHz PHS (Personal Handy phone System) band. The HIC at 880 MHz measures only 5. 05. 01. 0 mm3, and offered a conversion gain of 25 dB, a noise figure of 4. 2 dB and an image rejection ratio of 12 dB at 2. 7 V and at a power supply of 3. 5 mA. The HIC for 1. 9 GHz measures only 3. 54. 01. 0 mm3, and showed a conversion gain of 16. 0 dB, a II P3 of -16. 0 dBm, and an image rejection ratio of over 20 dBc at 3. 0 V and at power supply of 4. 5 mA.

Practical design procedure of a four-pole dual-mode cavity filter is explained in the details. Coupling matrix M of an elliptic function filter is derived analytically. The effects of septum thickness is studied experimentally. The dimensions of the aperture have to be modified due to the effects. This attempt had made the filter design very elegant, because no complicated calculation is required. A four-pole filter and a multiplexer are designed and constructed experimentally. They show very excellent performances in the 23 GHz band.

This paper describes design approach and power performance of a single 1. 5 V operation two-stage power amplifier MMIC for 2. 4 GHz wireless local area network applications. The MMIC with 0. 760. 96 mm2 area includes SrTiO3 (STO) capacitors with a high capacitance density of 8. 0 fF/µm2 and double-doped AlGaAs/InGaAs/AlGaAs heterojunction FETs with a shallow threshold voltage of -0. 24 V. Utilizing a series STO capacitor and a shunt inductor as an output matching circuit, the total chip size was reduced by 40% as compared with an MMIC utilizing SiNx capacitors. Under single 1.5 V operation, the developed MMIC delivered an output power of 110 mW (20.4 dBm) and a power-added efficiency (PAE) of 36.7% with an associated gain of 20.0 dB at 2.4 GHz. Even operated at a drain bias voltage of 0.8 V, the MMIC exhibited a high PAE of 31.0%.