System Concept of WIFI Based Passive Radar
01 Dec 2011-International Journal of Electronics and Telecommunications (Walter de Gruyter GmbH)-Vol. 57, Iss: 4, pp 447-450
TL;DR: In this paper idea of passive radar system based on popular wireless networks commonly named WIFI is presented and it is assumed, that all transmitters operate on the same band frequency and the passive radar receiver has to couple each transmission burst with transmitter position by decoding the physical address of transmitter from captured data stream.
Abstract: In this paper idea of passive radar system based on popular wireless networks commonly named WIFI is presented. In such an networks many transmitters operates in the same channel using multiple access. Wireless networks operating on frequencies 2.4GHz and 5GHz are very common today (IEEE 802.11 a/b/g/n). Classic passive radar determines bistatic distance and velocity by using cross-ambiguity function. To seek target position in XYZ space at least illumination of 3 different transmitters is required. In that paper it was assumed, that all transmitters operate on the same band frequency and the passive radar receiver has to couple each transmission burst with transmitter position by decoding the physical address of transmitter from captured data stream. Having most of the signal sources in our passive radar environment it is possible to detect and to localize objects of interest.
Citations
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TL;DR: A compressed sensing algorithm is proposed to achieve supper resolution and better accuracy, using both the atomic norm and the -norm, to manifest the signal sparsity in the continuous domain.
Abstract: In this paper, we consider the problem of joint delay-Doppler estimation of moving targets in a passive radar that makes use of orthogonal frequency-division multiplexing communication signals. A compressed sensing algorithm is proposed to achieve supper resolution and better accuracy, using both the atomic norm and the $\ell _1$-norm. The atomic norm is used to manifest the signal sparsity in the continuous domain. Unlike previous works that assume the demodulation to be error free, we explicitly introduce the demodulation error signal whose sparsity is imposed by the $\ell _1$-norm. On this basis, the delays and Doppler frequencies are estimated by solving a semidefinite program (SDP) which is convex. We also develop an iterative method for solving this SDP via the alternating direction method of multipliers where each iteration involves closed-form computation. Simulation results are presented to illustrate the high performance of the proposed algorithm.
131 citations
TL;DR: The results show that the signal-to-noise ratio (SNR) in the RC relative to the SNR in the SC has a significant impact on the passive MLE, and the Cramér-Rao Bound is derived to benchmark the passive estimation performance.
Abstract: We consider the problem of delay and Doppler frequency estimation of a moving target in passive radar using a non-cooperative illuminator of opportunity (IO). The passive radar consists of a reference channel (RC), i.e., an antenna steered to the IO, and a surveillance channel (SC) that collects target echoes. We examine the maximum-likelihood estimator (MLE) for the passive estimation problem by modeling the unknown IO waveform as a deterministic process. Under this condition, the passive MLE is shown to reduce to a cross-correlation and search process using the surveillance signal and a delay-Doppler compensated version of the reference signal. We present two implementations for the passive MLE, including a direct and, respectively, a fast implementation based on a two-dimensional Fast Fourier Transform. In addition, the Cramer-Rao Bound is derived to benchmark the passive estimation performance. The passive MLE is compared via numerical simulation with its active counterpart, which has the exact knowledge of the waveform and uses it for cross-correlation. Our results show that the signal-to-noise ratio (SNR) in the RC relative to the SNR in the SC has a significant impact on the passive MLE. Specifically, if the former is notably higher than the latter (by, e.g., 5 dB), there is a minor difference between the passive and active MLEs for the delay and Doppler estimation; otherwise, the difference is non-negligible and increases with the SNR.
15 citations
Cites background from "System Concept of WIFI Based Passiv..."
...With the advances of wireless communication technologies, a variety of IOs can be used for passive sensing, including analog FM radio [4] and television stations [5], digital audio/video broadcasting [6], wireless cellular [7], WiFi signals [8], [9],...
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01 Oct 2015
TL;DR: The main goal of this paper is to show how the amount of the illuminating signal impacts the range-Doppler matrix.
Abstract: WIFIRAD — a passive radar demonstrator developed at the Warsaw University of Technology — utilizes signals from the WIFI networks as sources of illumination. As these WIFI signals are not continuous and the duty factor depends on the amount of transmitted data by the WIFI network nodes, authors focused on an impact of the duty factor on the quality of the detections obtained by the WIFIRAD. This paper contains a description of the illuminating signal, a short analysis of an impact of the duty factor on a shape of the cross-ambiguity function and the results of the experiments. The experiment was planned to show how the amount of the traffic in the WIFI network impacts duty factor and how it impacts crossambiguity function obtained by the WIFIRAD. The set of experiments in the bistatic configuration were conducted in an outdoor environment using a 2-node WIFI network, the WIFIRAD as radar and a car as a target. The main goal of this paper is to show how the amount of the illuminating signal impacts the range-Doppler matrix.
9 citations
TL;DR: Modifications of the USRP's FPGA configuration and GNU Radio code are proposed for developing six/nine synchronous input channel receiver based on two/tree USRPs respectively and the solution of the problem of the alignment of the data streams being sent from USRP devices via USB to the PC host is proposed.
Abstract: In this paper we present results of research on multichannel receiver using Software Defined Radio technology. This receiver is a part of the experimental FM based passive radar being designed. The hardware platform of the receiver consists of the Universal Software Defined Radio Peripheral devices. In the paper we propose modifications of the USRP's FPGA configuration and GNU Radio code. These modifications allow for developing six/nine synchronous input channel receiver based on two/tree USRPs respectively. Issues of synchronization of separate USRP devices by assuring synchronous sampling were presented. We also propose the solution of the problem of the alignment of the data streams being sent from USRP devices via USB to the PC host.
8 citations
Cites methods from "System Concept of WIFI Based Passiv..."
...Another passive radar concept utilizing WIFI systems was presented by Rzewuski and Kulpa [9]....
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01 May 2018
TL;DR: The results of a dedicated acquisition campaign show that both the detection capability and the localization accuracy progressively degrade as the BI increases due to both the reduction of the received beacons and to the intrinsic undersampling of the target motion.
Abstract: The capability of WiFi-based passive radar to detect, track and profile human targets in both indoor and outdoor environment has been widely demonstrated This paper investigates the impact of the Beacon Interval (BI) on the passive radar performance The results of a dedicated acquisition campaign show that both the detection capability and the localization accuracy progressively degrade as the BI increases due to both the reduction of the received beacons and to the intrinsic undersampling of the target motion Limit values are suggested for practical applications
6 citations
References
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Proceedings Article•
01 Jan 2009
TL;DR: This paper addresses the real-time localization of transceiver-free targets is addressed by means of learning by example methodology that exploits the received signal strength indicator available at the nodes of a wireless sensor network as input data.
Abstract: The increasing demand in homeland security speeds up the development of innovative and non-invasive systems to localize and track moving objects in complex environments. In this paper the real-time localization of transceiver-free targets is addressed by means of learning by example methodology that exploits the received signal strength indicator available at the nodes of a wireless sensor network as input data. This approach uses neither dedicated sensors nor active devices put on the target to localize both idle and moving objects. The definition of a customized classifier during an offline training procedure enables the real-time generation of a probability map of presence by processing the output of the support vector machine. Some selected experimental results validate the effectiveness of the proposed methodology applied in real scenarios.
4 citations
"System Concept of WIFI Based Passiv..." refers methods in this paper
...The indoor applications are also possible, but they should rely mostly on Doppler processing and power budget analysis and were presented by Viani, Olivieri, Massa [2]....
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