Yoichi Nakagawa

An experimental study of DOA estimation in multipath environment using an adaptive array antenna equipment

This paper reports the experimental results of DOA estimation for the 2-GHz band using adaptive array antenna equipment we developed. We evaluated the accuracy of the DOA estimates in a multipath environment using MUSIC and ESPRIT with a spatial smoothing technique. The experiments were performed in an anechoic chamber and outdoors. We show the effect of beamforming control from the viewpoint of improving BER performance.

Channel synthesized modulation employing singular vector for secured access on physical layer

This paper proposes the channel synthesized modulation (CSM) employing singular vector. The channel synthesized modulation is designed to decompose the modulation waveform to n transmitting signals according to the channel parameter between transmitter and receiver. Since the singular value decomposition (SVD) produces singular vectors as characteristics of matrix, these are suitable parameters for the channel synthesized modulation to decompose. And these parameters also enable establishment of secured access easily. This paper describes the principle of the channel synthesized modulation and SVD analysis, and introduces secured access employing the singular vectors with the channel synthesized modulation, and then shows its performance.

Advanced millimeter-wave radar system using coded pulse compression and adaptive array for pedestrian detection

This paper reports a radar system design using millimeter-wave for vehicular and pedestrian safety around intersections. The proposed system design and associated key algorithms are embedded into a prototype and verified in an anechoic chamber and a trial intersection. The system covers 30 cm range resolution, 5-degree angle resolution, 95% detection rate and 10% false alarm rate. The results therefore prove the system feasibility for future automotive safety application.

Advanced code sequences design for pedestrian detection in millimeter-wave pulse-compression radar system

The paper proposes code sequences with an optimized criterion for precisely detecting pedestrians in the presence of vehicles in millimeter-wave pulse-compression radar system. The criterion named FR (Floor-Ratio) focuses on the maximum of sidelobes. The code sequences based on FR attain higher maximum sidelobe suppression compared to the ones based on conventional criterion. Computer simulation and experimental measurement have been done for verification. Consequently, our work proves the effectiveness of the proposed code sequences with the criterion for next generation millimeter-wave radar systems.

Millimeter-wave radar combining Tx beamforming and Rx array processing for precise pedestrians detection

The advanced radar detection method which combines Tx beamforming and Rx array processing with highresolution direction of arrival (DOA) estimation is proposed. The proposed method associates DOA estimation direction with Tx beamforming direction (TxD-DOA) for a high accuracy detection for multiple targets in millimeter-wave radar system. Computer simulation and experiment evaluation verify the improvement effects of the TxD-DOA method. We have confirmed that the suppression of multiple radar reflection waves by the transmission beam scanning brings the better DOA estimation accuracy and higher angular resolution of the TxD-DOA for multiple human targets.

Advanced wide field of view millimeter-wave radar using orthogonal complementary codes

This paper reports a radar system design using 79GHz millimeter-wave for vehicular and pedestrian safety around intersections. The proposed system design and associated key algorithms are embedded into a prototype and verified in an anechoic chamber and a field experiment. The system covers the distance of 40m and the azimuth angle of 120° range with high range and angular resolution (20cm, 5-degree), and can detect pedestrians within short budget of 100ms by using orthogonal complementary codes which are transmitted by Tx dual beamscanning to suppress the interference between the two divided area. The results therefore prove the system feasibility for future automotive safety application.

Improved method for evaluating antenna performance in mobile environment with consideration of polarization and phase

The paper presents an improved method for evaluating antenna performance in a multipath propagation environment. It demonstrates, theoretically and experimentally, that by using polarization and phase terms of the incident field and the antenna system in the evaluation of the antenna effective gain (AEG), the AEG can be evaluated more efficiently as compared with the conventional method. First, a theoretical expression of the received power is given by using the open-circuit voltage at the antenna terminals, in which both the polarization and the phase of the incident field and antenna gain patterns are explicitly used. Secondly, a newly developed system for the measurement of field parameters, such as polarization and phase as well as amplitude, is introduced. Thirdly, incident field parameters measured in urban and suburban areas of Tokyo are described. It was confirmed that major incident waves were counted in up to five or six directions at a mobile terminal and their polarizations and phases were different depending on the direction of incidence. Also, measurement of the antenna gain patterns of the latest personal digital cellular handset at a talk position finds the dependence of the AEG on polarization and phase, which were significantly varied by the body effect. Finally, the AEG is evaluated based on the method introduced here, and its usefulness is compared with that of the conventional method.

79GHz-band radar cross section measurement for pedestrian detection

This paper presents radar cross section (RCS) measurement for pedestrian detection in 79GHz-band radar system. For a human standing at 6.2 meters, the RCS distributions median value is -11.1 dBsm and the 90 % of RCS fluctuation is between -20.7 dBsm and -4.8 dBsm. Other measurement results (human body poses beside front) are shown. And we calculated the coefficient values of the Weibull distribution fitting to the human body RCS distribution.