Large scale path loss measurements in sea port are presented. This investigation is useful before deploying Worldwide Interoperability for Microwave Access (WiMAX) equipments to provide last mile Broadband Wireless Access (BWA) for ships and boats in the sea port. Measurements were carried out at 5.8 GHz. Two-ray model fits measured large scale path loss reasonably well. When the distance is very large, the received signal was found to attenuate at the rate of more than double of that of the free space. The attenuation rate was found to depend on the antenna's height.
Most currently existing algorithms used in SOPLAT (single observer passive location and tracking) system usually select single parameter measurement set which concludes only a little measured information, which means that they do not consider and make full use of spatial and temporal information as well as frequency range information which can be measured synchronously by modern electronic detecting equipment. In order to overcome this drawback, a new fusion optimization filtering algorithm for SOPLAT system is presented, this algorithm can fully utilize the redundant information coming from many sensors, which includes TOA, DOA and Doppler frequency measurements,etc. The proposed method improves further the location & tracking accuracy, reliability and defensive operational capability of the system by using data fusion technology. As a demonstration to evaluate the method described in this paper, two simulation examples are presented which indicate the effectiveness and feasibility of this filtering algorithm, and the results show that this method has better accuracy and convergence rate than conventional algorithms. key word: passive location; data fusion; time and direction of arrival; nonlinear system, optimization
Nowadays, with the ubiquitous presence of the Internet of Things industry, the application of emerging sensor networks has become a focus of public attention. Unattended sensor nodes can be comprised and cloned to destroy the network topology. This paper proposes a novel distributed protocol and management technique for the detection of mobile replicas to tolerate node failures. In our scheme, sensors’ location claims are forwarded to obtain samples only when the corresponding witnesses meet. Meanwhile, sequential tests of statistical hypotheses are applied to further detect the cloned node by witnesses. The combination of randomized detection based on encountering and sequential tests drastically reduces the routing overhead and false positive/negative rate for detection. Theoretical analysis and simulation results show the detection efficiency and reasonable overhead of the proposed method.
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