Hidehisa Shiomi

Acceleration of FPGA-based ICA processor for real-time processing

The ICA (Independent Component Analysis) is one of the blind signal separation technologies. It is very useful for MIMO (Multiple-Input Multiple-Output) system. In MIMO communication system, the estimation of the propagation channel is necessary for good communication. We can estimate it except for pilot symbols by using the ICA.

Experiment of blind signal separation of wireless mixture using complex valued fast independent component analysis

The blind estimation technique is useful for an adaptive array antenna, a MIMO communication system and a cognitive wireless communication system. The independent component analysis (ICA) developing in the area of the image processing and the speech processing is a simple algorithm with demand upon less priori knowledge. In this report, it is described that an experiment of the blind signal separation of the microwave mixture signal consisted of two signals with QPSK modulation. The digital wireless communication system with two transmitters and two receivers was setting up to obtain the microwave mixture where a carrier frequency was 2.45GHz. The separated signals from the mixture using the ICA were good agreement with the source signals.

Phase control experiment of the PLL oscillator for a phased array antenna

The space solar power system (SSPS) requires a large phased array antenna (PAA) with high efficiency and high accuracy but with the conventional method there arises the problem of loss in splitters and phase shifters. In this research, we use a structure integrates phase-locked loop (PLL) oscillators to each antenna element, in order to achieve the objective of simplifying the antenna and increasing its efficiency the simplification and efficiency of the antenna. To make it work as a PAA, we generate a phase difference between the PLL oscillators by controlling the charge pump (CP) output in the oscillators. In the experiment, synchronous detection is performed by using two PLL oscillators; we confirm that it is possible to control the phase difference to 360°. In addition, the phase difference is found to vary in proportion to the CP output.

Highly angle and frequency selective absorption by mushroom metasurfaces for indoor propagation control

Highly angle and frequency selective, very high absorption over 35 dB is observed by a two-dimensional array of mushroom structure artificially constructed on a very thin (∼ λ/20) dielectric substrate. The prototypes operating at the V-band are designed and their angle selectivity and absorption level are measured by using a free-space measurement system. It is shown that the high absorption occurs in consequence of exciting the guided waves in the mushroom structure by incident waves with a certain angle and certain frequencies.

Array-antenna-electrode electro-optic modulator for millimeter-wireless communication systems

An array-antenna-electrode electro-optic modulator has been designed and demonstrated for millimeter-wave wireless frequency bands. By utilizing a thin LiNbO3 crystal film attached on a base glass substrate of low-dielectric constant, a high-performance operation in millimeter-wave bands can be obtained. The design and experimental verification of the proposed device have been reported. We believe that it will be a key-device for 5G mobile networks.

Array-antenna-electrode electro-optic modulators for millimeter-wave up-links in wireless communication systems

We have proposed and developed array-antenna-electrode LiNbO3 modulators operating in the millimeter-wave frequency band. In this paper, high-antenna-gain structures for up-links in wireless communication systems are discussed.

Phase variable PLL oscillator using imperfect integral loop filter

In recent years, with the spread of the broad band communication, higher frequency is proceeding. In particular, the millimeter-wave with a wide bandwidth has received a lot of attention. The millimeter-wave phased array capable of directional communications by a high gain antenna is necessary so that the free space transmission loss is large [1]. However, the phase shifter needed for the phased array has the large loss in the millimeter-wave band. Therefore, the local phase shifter type or amplifier has an advantage in electric requirements [2]. In this paper, we propose a phase variable phase lock loops (PLL) oscillator using imperfect integral loop filter as the mechanism to enable local signal phase to shift. The circuit configuration to achieve a beamformer by the oscillator array is simple and expected for low power. In the experiment, PLL output phase was shifted by controlling the leak current in the loop filter.

An FPGA implementation of complex valued independent component analysis for real-time interference canceler

This paper describes the demonstration of ICA (Independent Component Analysis) processor for radio applications. ICA determines the weighting vector of the array antenna to eliminate undesired arriving signals without any teaching signals. We believe that the ICA is useful to DOA estimation of the pilot signal from the Earth. In order to reduce dissipation power and to achieve higher processing speed, the ICA processor using FPGA or ASIC is strongly required. At first, fundamental theory of the ICA is described. Next, a fabricated processor and experimental system will be shown. The 4 element monopole array was used. The carrier frequency was 2.45GHz and the symbol-rate of pilot signals were 10kSym-bol/s. The receiver was received the single pilot signal with 3 undesired interferences. The fabricated processor estimate the separation weight every 262µs. Finally, the experimental results will demonstrate. Compared with typical procedure using measured channel matrix, ICA was recovered the SNR of 4 dB grater than typical method.

Electro-optic microwave-lightwave converter using patch antenna embedded with a narrow gap for optical modulation

New electro-optic microwave-lightwave converters using a patch antenna embedded with a narrow gap are proposed. Basic operations for the conversion from wireless to optical signals were demonstrated at 18 GHz with no external power supply.

Implementation of the independent component analysis processing circuit for wireless communications by FPGA

The blind estimation technique is very useful for an adaptive antenna and a MIMO communication system. Independent component analysis (ICA) which is studied briskly in the field of image processing or signal processing, is convenient means because there are few restrictions of previous knowledge. In order to perform signal separation by ICA on real time, it is necessary to perform repeated calculation of restoration vectors to less than about 0.4 millisecond. In this research, FPGA implements a part of processing of the complex value fastICA which is a way method of ICA. Main results show that the FPGAs computation is about 1000 time faster from PCs computation. Thereby, realization of a real-time operation will also be considered from now on.