Toshihiro Yamaguchi

Localization of illegal radios utilizing cross-correlation of channel impulse response with interpolation in urban scenarios

Fingerprint-based localization is expected to be superior compared to other conventional range-based localization techniques especially in dense urban scenarios which are generally non line-of-sight (NLOS). However, when we consider localizing illegal radios whose parameters such as bandwidth and center frequency are unknown, there is a high possibility that the initial parameters used to create the fingerprint database in the training phase do not match the illegal radios parameters. In this paper, a novel fingerprint-based localization technique which utilizes interpolated channel impulse response (CIR) cross-correlations as fingerprints is proposed, which does not require a priori information of the illegal radio. Results show that the proposed technique is very promising in localizing illegal radios in urban NLOS environments.

Implementation and Evaluation of 4×4 MIMO Fading Simulator Considering Antenna Characteristics

A 4 times 4 MIMO fading simulator (MIMO-FS) was constructed for the development of MIMO products. This MIMO-FS consists of multi-port up/down converters for 2.4/5.2GHz bands and baseband reconfigurable digital signal processors which allows the implementation of various MIMO channel models. In this paper, extended IEEE802.11n channel model including antenna characteristics and its hardware implementation are given as well as the system evaluation results.

Multi-sensor location estimation for illegal cell-phone use in real-life indoor environment

This paper proposes a novel method for location estimation of a cell-phone in an indoor environment with experimental validation. The proposed method is a location fingerprint scheme which employs the statistical characteristics of the signal cross-correlation among multiple sensors. As the cross-correlation between a pair of antennas fully stores the information of their complex channel responses, the proposed method can be considered as a generalized scheme of all conventional location fingerprint ones i.e. Received Signal Strength Indicator (RSSI), Time Difference of Arrival (TDOA), and Direction of Arrival (DOA). Besides, different from the conventional methods, in which the locality of spatial correlation is utilized, thus fine grid location measurements is required and environment must be static, the proposed one invokes statistical learning technique and estimates location based on the correlation of received samples with the statistical learning database. Therefore, the proposed method is superior to conventional ones in terms of location estimation accuracy and installation simplicity. An experiment conducted in class room validates the superiority of the proposed method.

A Novel Phase-Difference Fingerprinting Technique for Localization of Unknown Emitters

Localization of unknown emitters is crucial to tackle illegal radios or radio jammers which may cause harmful interference to other communication systems and disrupt services. Conventional fingerprint-based localization techniques that utilize received signal strength or channel information as location fingerprints may face problems when dealing with emitters whose parameters, such as center frequency, are unknown. In this paper, a novel localization algorithm utilizing the phase-difference between elements of an antenna array as location fingerprints is proposed. The training fingerprints are interpolated in the frequency and spatial domains before performing pattern matching with the unknown emitters fingerprints. Localization accuracy was evaluated through ray-tracing and Monte Carlo simulations, and results indicate that the proposed technique achieved relatively good performance compared to other localization techniques.