Hiroyo Ogawa

Millimeter-wave fiber optics systems for personal radio communication

System concepts for millimeter-wave personal communication systems and the advantages of millimeter-wave band usage are briefly described. Demonstration of broadband millimeter-wave subcarrier transmission concepts over fiber-optic links is performed. Several fiber-optic link architectures, including one using a combination of direct laser modulation and indirect (external) optical modulation, are outlined with respect to signal transmission at millimeter-wave frequencies. Several configurations are experimentally investigated using 70-MHz, 300-MHz, and 26-GHz subcarriers which transmit either FM or QPSK data signals. Additionally, the use of optical MMIC technology, which can result in the design of compact and cost-effective optical receivers, is described with respect to personal communication radio base station equipment. MMIC HEMTs operating as photodetectors are newly characterized in terms of digital and analog signal reception with excellent performance being observed. >

Millimeter-wave remote self-heterodyne system for extremely stable and low-cost broad-band signal transmission

We have developed a millimeter-wave remote self-heterodyne transmission system that enables extremely stable and low-cost broad-band transmission in the millimeter-wave band. The system was applied to a 60-GHz-band transmission system for the first time. The transmitter of the developed system transmits RF modulated signals and a local oscillation signal simultaneously, and the receiver detects these signals by using a square-law-type detection technique, thus creating a very stable and low phase-noise millimeter-wave transmission link without the use of an expensive and more advanced frequency-stabilization technology. Since the receiver no longer requires a millimeter-wave oscillator for frequency conversion, the devices used in this system can be miniaturized and the cost of the system can be reduced. This paper discusses the performance of the developed system in terms of its phase-noise degradation and carrier-to-noise power ratio (CNR). We also discuss the optimal transmitter design to obtain the maximum CNR. Using our miniaturized monolithic millimeter-wave integrated-circuit-based 60-GHz-band experimental system, we demonstrate that our millimeter-wave transmission link is completely free of phase-noise and frequency-offset degradation due to the use of a millimeterwave local oscillator. We show that equal transmission-power distribution between the RF signal and local carrier gives the maximum CNR under the transmission-power-limited conditions. Also, we demonstrate that QPSK-modulated satellite broadcast multichannel video signals with a 300-MHz bandwidth, in total, can be successfully transferred over a distance of 8 m.

Multilayer MMIC directional couplers using thin dielectric layers

Low-loss and small-sized MMIC directional couplers utilizing a multilayer structure composed of coupled thin-film transmission lines on a GaAs wafer surface are newly proposed. The fundamental characteristics of the couplers are discussed through calculations by numerical analysis, and the performance of the couplers and an application to reverse-phase hybrid ring are demonstrated. The results show that a 3 dB coupler can be designed within a 0.8 mm/spl times/0.8 mm area for a center frequency of 20 GHz. Coupling losses of 3.7 dB/spl plusmn/0.2 dB over a 4-GHz bandwidth and isolation of better than 26 dB in the frequency range of 0-30 GHz are achieved. The proposed coupler configurations can be applied to the high-density and multifunction integration of MMICs. >

Analysis of CPW for LiNbO/sub 3/ optical modulator by extended spectral-domain approach

A LiNbO/sub 3/ optical modulator using CPW with a SiO/sub 2/ buffer layer is analyzed accurately by incorporating the TW electrode thickness effect as well as anisotropic effect. By introducing a finite electrode thickness, the loss calculation becomes available for the lines with thinner as well as thicker conductors. Numerical computations show that the electrode thickness is as important a parameter as the buffer layer thickness for the line characteristics. The use of thicker electrodes increases the velocity of microwaves in the interaction part and decreases the conductor loss significantly, and it can be utilized advantageously for the modulators design.<<ETX>>

Megalithic microwave signal processing for phased-array beamforming and steering

A microwave signal processing (MSP) architecture is presented for active phased array beam forming and steering. A large scale network, comprising 63 power dividers and 32 pairs of orthogonal phase-amplitude controllers, has been successfully developed in a single GaAs MMIC. This megalithic chip could mark an epoch in phased-array antenna systems.

A Wireless Video Home-link Using 60GHz Band: Concept and Performance of the Developed System

A concept and requirements of a millimeter-wave video transmission system as a wireless home-link using 60-GHz band are described. This system can transmit broadcast television (TV) signals from TV antennas to TV set and thus can be regarded as a substitute for a feeder line. The feasibility study by investigating the systems CNR and SNR performances using MMIC-based experimental setup is also described.

A Modified SV-Model Suitable for Line-of-Sight Desktop Usage of Millimeter-Wave WPAN Systems

A modified Saleh-Valenzuela (SV) model, which is useful in designing a millimeter-wave WPAN (mmW WPAN) system for line-of-sight (LoS) desktop environments, is proposed. It is demonstrated that a well-known two-path model component is dominantly observed in a typical LoS desktop channel along with the components of the other non-line-of-sight (NLoS) paths. Then, the deterministic two-path model is extended to a statistical two-path model by introducing random variables for the antenna position and merging with the conventional SV-model which is suitable to express NLoS path components. The proposed channel model parameters are extracted in a typical LoS desktop environment, and then the cumulative distribution of total path power gain is discussed using a simulation technique that assumes a specific antenna location scenario. It is shown that the cumulative distribution of total path power gain obtained using the proposed model is useful to estimate the outage probability of the mmW WPAN link.

70-GHz-Band OFDM Transceivers Based on Self-Heterodyne Scheme for Millimeter-Wave Wireless Personal Area Network

70-GHz-band orthogonal frequency-division multiplexing (OFDM) transceivers were developed by combining self-heterodyne transmission with two-element diversity reception. The transceivers were used to study and demonstrate a millimeter-wave wireless personal network that enables cost-effective broadband data transmissions in a multipath channel environment. A 100-MHz sampling OFDM modulator/demodulator was developed for the baseband part. It has a payload data rate of 100 Mb/s using quadrature phase-shift keying (QPSK) modulation and a coding rate of 3/4 (many other modulations and coding rate are available). The bit error rate was experimentally evaluated when a pair of devices was placed on a wooden table under line-of-sight path conditions. The results showed that the combined use of the self-heterodyne technique and two-element diversity receiver successfully avoids serious signal fading at unpredictable transmission distances. The transceiver with QPSK modulation and coding rate of 1/2 for forward error correction achieves error-free data transmission over a distance of up to 3.4 m. In addition, a successful transmission in 64 quadrature amplitude modulation mode was demonstrated, although the communication range was quite short

Photonic switched true time delay beam forming network integrated on silica waveguide circuits

This paper proposes an integrated variable true time delay (TTD) beam forming network (BFN) on the silica-based optical waveguide circuits. This BFN has thermooptic switches and variable time delay lines. The variable TTD unit test was carried out under the 2.5 GHz microwave frequency range. The experimental results show that the phase error, that is the difference from the designed value, is less than or equal to 0.6 degrees and the amplitude error is less than or equal to 0.5 dB. These results also show adequate performance for a variable delay line. This silica-based beam former will be one of the excellent alternatives for the phased array antennas.<<ETX>>

Millimeter-Wave Fiber-Fed Wireless Access Systems Based on Dense Wavelength-Division-Multiplexing Networks

This paper describes new 60-GHz-band bidirectional fiber-fed wireless access systems, which provide simple antenna base-station architecture and full compatibility with dense wavelength-division multiplexing (DWDM) fiber-optic networks. For downlink millimeter-wave signal generation, the proposed scheme utilizes uplink optical transmitters as downlink optical heterodyne sources, which promises wavelength allocations of downlink and uplink signals that are fully compatible with those of DWDM networks. The frequency instability and poor phase-noise characteristics of these optically heterodyned signals do not affect transmission quality at all by using self-heterodyne wireless transmission techniques. Experimental results demonstrate that the proposed scheme provides not only strong immunity to phase-noise degradation coming from both fiber and millimeter-wave links, but also less sensitivity to fiber transmission loss than conventional remote optical heterodyne approaches. With the help of these attractive features, we successfully demonstrate both downlink and uplink orthogonal frequency-division multiplexing data transmissions in both 10-km fiber-optic and 60-Hz links.