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In order to monitor continuously moving phenomena such as wile fire and hazardous bio-chemical material in wireless sensor network, boundary tracking approach has been widely used by reason of its huge scale and extensive diffusion property. With the boundary tracking scheme, the energy efficiency is expected to improve if only sensor nodes near the boundary of continuous object actively participate...
The unavoidable Doppler frequency shift reduces the correlation peak for code acquisition in global positioning system (GPS). In contrast to conventional methods where the code phase and Doppler frequency shift are separately treated, this paper proposes a novel three-step scheme for joint code acquisition and Doppler estimation, whereby not only the Doppler effect on the correlation peak is removed,...
A novel joint blind channel estimation and turbo equalization algorithm is proposed for orthogonal frequency-division multiplexing (OFDM) system in this paper. It has been proved that, blind channel estimation based on linear precoding can obtain channel information exactly. However, the precoding will cause inter-symbol interference (ISI). With the existence of ISI, the bit error rate (BER) performance...
We consider the problem of quantized target tracking in wireless sensor networks (WSN) where the observed system is assumed to evolve according to a probabilistic state space model. We propose to improve the use of the quantized variational filtering (QVF) by jointly estimating the target position and selecting the best sensors that participate in data association. In fact, the QVF has been shown...
In this paper, we devised a novel indoor navigation system based on a probabilistic approach that employs data from the wireless adapter, accelerometer, and compass of the mobile device in order to determine user position. A routing algorithm employed by the device calculates the optimal path between user position and its destination. Experimental results verified that two meter accuracy was achieved...
The almost Gaussian nature of OFDM (Orthogonal Frequency Division Multiplexing) signals with high number of subcarriers is widely employed to characterize nonlinearly distorted OFDM signals and to evaluate the corresponding performance. In this paper we study the accuracy of the Gaussian approach when evaluating nonlinear effects in OFDM signals with finite number of subcarriers, showing the strengths...
We study data fusion in sensor networks using mobile agents (MAs),which are capable of saving energy of sensor nodes and performing advanced computation functions based on the requests of various applications. Research on MAs still remains unfledged in development of application-oriented data fusion, which is highly desired in wireless sensor networks (WSNs) deployed in recent days for environmental...
Under the assumption of single bounce channel model, the position and velocity of a mobile station (MS) can be determined by time of arrival (TOA), angle of arrival (AOA) and doppler-shifted frequency (DSF) measurements at three base stations (BSs) when line of sight (LOS) paths between the three BSs and the MS are all blocked. The equations relating the measured TOAs, AOAs and DSFs to the location...
To improve the performance of spectrum sensing, cooperation among Cognitive Radios (CRs) has been proposed recently as an effective solution. A great part of the existing spectrum sensing algorithms adopt synchronous spectrum sensing method, while the rest asynchronous spectrum sensing algorithms have a severe demand for terminals' sensing performance. This paper proposes a novel Triggered Asynchronous...
In this paper, we show the characteristics of the threshold-based IR-UWB location positioning system by experiment. We found that this system provides distance-dependent accuracy because the arrival time of the pulse is detected by threshold using 1-bit ADC (Analog to Digital Convertor). We also propose a simple compensation method based on measurement to improve positioning accuracy. The proposed...
WLAN RSS-based localization has been a hot research topic for the last years. To obtain high accuracy in the noisy wireless channel, WLAN location determination systems usually use a calibration phase, where a radio map, capturing the signal strength signatures at different locations in the area of interest, is built. The radio map construction process takes a lot of time and effort, reducing the...
Nonparametric belief propagation (NBP) is one of the best-known methods for cooperative localization in sensor networks. It is capable to provide information about location estimation with appropriate uncertainty and to accommodate non-Gaussian distance measurement errors. However, the accuracy of NBP is questionable in loopy networks. In this paper, we propose a novel approach, NBP based on spanning...
To improve the performance of a received signal strength indication (RSSI)-based maximum likelihood (ML) location estimation method, we have so far proposed an area layout-based maximum a posterirori (MAP) location estimation method for a stationary target. For the MAP location estimation, we have derived the priori probability density function of a target location, and shown the improvement of the...
Existing works on joint carrier frequency offset (CFO) and channel estimation in two-way relay networks (TWRN) only deal with the composite channel parameters and the mixed CFO values. In this paper, we design a superimposed pilot based training strategy such that the individual frequency and channel parameters can be obtained at the source terminals. We consider the amplify-and-forward (AF) relaying...
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