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This paper addresses the problem of compensating for motion-induced Doppler frequency offset in multicarrier acoustic communication systems based on orthogonal frequency division multiplexing (OFDM). In mobile acoustic systems, Doppler effect can be sever enough that the received OFDM signal experiences non-negligible frequency offsets even after initial resampling. To target these offsets, a practical...
This paper presents a technique by which a low-cost, minimally-equipped unmanned underwater vehicle (UUV) can localize itself while submerged using acoustic emissions of transiting sources of opportunity (SOOs). The technique provides a bounded estimate of the UUV position and is intended to supplement the on-board Inertial Navigation System (INS). The technique exploits two physical phenomena, the...
The paper considers the problem of improving the reliability of the hardware and software of autonomous unmanned underwater vehicles. The aim of the work is to investigate and develop methods for emergency homing of the AUV to the source of the reference signal using minimal input data. The idea is proposed of estimating the speed of the source and receiver approach by analyzing the deviation of the...
Recently underwater wireless communication has been receiving a lot of attention as it is essential to facilitate new industries and applications such as deep sea mining, ocean monitoring, submarine communication, and so on. Latest studies have showed Space-Frequency Block Code (SFBC) OFDM which was studied thoroughly in radio wireless communication is a promising candidate for underwater acoustic...
Chirp slope keying (CSK) modulation based on linear frequency modulation signal (LFM) and hyperbolic frequency modulation signal (HFM) combined with passive time reversal (PTR) for mobile underwater acoustic communication is proposed in this paper. For CSK modulation, the carriers are LFM and HFM signals, and the bit information is represented by different signals. A PTR processor is designed at the...
This paper studies the channel estimation and equalisation of orthogonal frequency-division multiplexing (OFDM) systems over doubly selective channels. We consider practical channel estimation schemes based on basis expansion model (BEM) and clustered pilots. We investigate the influence of the parameters of the channel estimation scheme, including the dimensionality of the BEM basis and bandwidth...
In this paper, we propose a new method to compensate Doppler frequency shift for OFDM-based underwater acoustic communication systems. In order to save bandwidth, we do not use additional signal header (preamble) in each OFDM frame as proposed in many conventional approaches. Instead, the central sub-carrier is reserved for pilot transmission. This subcarrier is so-called as the carrier frequency...
Typical Global Positioning System (GPS) receivers, which are increasingly used in many areas, consume too much energy due to heavy processing in a long time. This makes them not useful and sometimes even impractical for applications with high mobility or operating in obstructed regions where the GPS signal is present in short time. To address the problem, we propose a new design for a fast GPS receiver...
The mobile underwater acoustic channel has brought a great challenge on the encoding and decoding process. The recent development of underwater acoustic processing method aims to get a lower bit error rate(BER). However, the controdiction between lower BER and real-time transmission are not well solved. In this paper, we reach a compromise between them, we combine the turbo code with the adaptive...
This paper presents a method for studying the performance of mode-stirrers used in Reverberation chamber (RC) by studying their Doppler spectrum obtained in free space or in RC. Indeed, a mode-stirrer must have the largest diffracting properties corresponding to a Doppler Spectrum as spread as possible. For this purpose, a simple analytical model is proposed in order to obtain the Doppler spectrum...
Evolution of modern communications and radar systems have steadily increased the demand on modelling the propagation effects with real world scenarios for various signal types. The main purpose of this research is to create a flexible, generic and realistic Radio Frequency (RF) environment simulator including both radar and communication signals. Software defined radio (SDR) platform has been utilized...
We proposed a novel Doppler effect based microwave frequency mixer which mixes the incident wave with its Doppler shifted signal, instead of a local oscillator. The Doppler shifted signal originates from an effective moving reflective surface built inside the mixer. This kind of mixer can be low-cost without local oscillators, meanwhile the intermediate frequency is tunable electronically.
This paper focuses on performance evaluation of waveforms in the fifth generation, i.e. universal-filtered multi-carrier technique (UFMC), resource block filtered orthogonal frequency-division multiplexing (RB-F-OFDM), filtered-OFDM (F-OFDM), and filter-bank multi-carrier (FBMC) in high speed scenarios. The block error rates (BLERs) of the channel model of tapped-delay-line-D (TDL-D) defined in 3GPP...
We introduce a new scheme that integrates the Time Compression OverLap-Add (TC-OLA) spread spectrum technique into radar systems, more specifically the Linear Frequency Modulation Pulse Compression (LFM-PC) radar. This technique increases the signal to noise ratio (SNR) and, as a consequence, enables a greater processing gain compared to the traditional radar LFM-PC systems. In addition, TC-OLA allows...
This summary presents an adaptive large-size moving target imaging technique for bistatic forward-looking SAR (BFL-SAR). The main problems of this issue are that not only the echo characteristics (including range cell migration and Doppler parameters) are unknown, but also the spatial-variances of these characteristics are nonlinear for different point-scatterers. The proposed technique relies on...
Cooperative localization systems require some kind of communication between the different members of the network. In underwater environments this communication is not trivial, since it is based on acoustic signals that propagate in a challenging environment characterized by multipath, Doppler effect and long delays. To avoid collisions between the different members of the network, usually a Time-Division...
Passive radar detection systems based on Global Navigation Satellite System (GNSS) signals have the advantages of wide coverage, long detecting distance and good concealment. If effectively combined with the forward scatter radar (FSR) principle, it can be used to monitor an important area, which is of great significance to national defense security. This paper mainly focused on the analysis of signal...
This paper focuses on the estimation of target's motion parameters in a moving transmitter/moving receiver forward scatter radar scenario. An extension of the quasicoherent processing initially developed for stationary FSR mode of operation is introduced. This offers an estimation of the target's trajectory in a general case where transmitter and receiver can be moving. Simulated and real data are...
Multiple-input multiple-output (MIMO) radars with wideband signals are useful to discriminate target in clutter. With wideband MIMO radar, the problem of extended target detection in compound-Gaussian clutter is considered in this paper. By obtaining target echoes from each antenna, the detector based on generalized likelihood ratio test (GLRT) is developed. It shows that the shape parameter of clutter,...
Car drivers' sudden illness cause serious traffic accident. In Japan, it is reported by a medical doctor that the most of the illness causing serious traffic accident is induced by heart abnormalities. This situation is concerned along with coming aging society. Non-contact monitoring using a Doppler sensor is one of the attractive solutions for this matter since there is no need to put sensors on...
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