Current Issue : October - December Volume : 2019 Issue Number : 4 Articles : 5 Articles
The Global Positioning System (GPS) has been widely applied in outdoor positioning,\nbut it cannot meet the accuracy requirements of indoor positioning. Comprising an important part of\nthe Internet of Things perception layer, Radio Frequency Identification (RFID) plays an important\nrole in indoor positioning. We propose a novel localization scheme aiming at the defects of existing\nRFID localization technology in localization accuracy and deployment cost, called ANTspin: Efficient\nAbsolute Localization Method of RFID Tags via Spinning Antenna, which introduces a rotary table in\nthe experiment. The reader antenna is fixed on the rotary table to continuously collect dynamic data.\nWhen compared with static acquisition, there is more information for localization. After that, the\nrelative incident angle and distance between tags and the antenna can be analyzed for localization\nwith characteristics of Received Signal Strength Indication (RSSI) data. We implement ANTspin\nusing COTS RFID devices and the experimental results show that it achieves a mean accuracy of\n9.34 cm in 2D and mean accuracy of 13.01 cm in three-dimensions (3D) with high efficiency and low\ndeployment cost....
This paper aims to provide a comprehensive scheme with limited feedback for downlink millimeter wave (mmWave) multiuser\nmultiple-input multiple-output (MIMO) nonorthogonal multiple access (NOMA) system. Based on the feedback of the best beam\nand the channel quality information (CQI) on this beam, the users are grouped into a cluster having the same or coherent best\nbeam and the maximal CQI-difference. To further reduce the intercluster interference, only the candidate cluster can join the\ncluster set whose intercluster correlation with the existing clusters is lower than threshold. Based on the results of clustering,\nmmWave hybrid beamforming is designed. To improve the user experience, each cluster selects the best beam of the user with\nthe higher guaranteed rate requirement as the analog beamforming vector. For digital beamforming, the weak user applies the\nblock diagonalization algorithm based on the strong userâ??s effective channel to reduce its intracluster interference. Finally, an\nintracluster power allocation algorithm is developed tomaximize the power difference in each clusterwhich is beneficial to improve\nthe successive interference cancelation (SIC) performance of the strong user. Finally, simulation results show that the proposed\nMIMO-NOMA scheme offers a higher sum rate than the traditional orthogonal multiple access (OMA) scheme under practical\nconditions....
A theoretical model of the sky-wave path propagation with frequency modulated continuous wave (FMCW) source for high\nfrequency (HF) radar is proposed in this paper. Based on themodeling of pulsed source, the expression of the received electric field\nwith anFMCWsource is derived for the reflection case fromthe ionospheric irregularities. Subsequently, the ionospheric reflection\ncoefficient with different phase power spectrums for vertical and oblique backscattering propagation paths is incorporated into the\nionospheric cluttermodel. Simulation results show that the peak power of FMCWin average is lower than that of pulsed waveform.\nFurthermore, different incident angles andmagnetic field inmid-latitude can also influence the power density of the backscattering\nionospheric clutter. Finally, the data analysis results fromthe high frequency surface wave radar (HFSWR) and Ionosonde collected\nin Yellow Sea preliminarily verify the inversion of the variance of the electron density fluctuation and the vertical drift velocity of\nthe irregularities within ionosphere....
A planar beam steerable array antenna system is proposed with dual-control circuits for feeding and reactive loadings. Two\northogonally arranged planar dipoles are excited by SPDT switching circuits, while the forward and backward beam directions\nare controlled by the adjusted effective electric lengths of the parasitic dipole elements. The adjusted parasitic dipoles are\ndesigned to play the alternative roles of directors and reflectors based on the Yagi-Uda antenna theory. The proposed antenna\nsystem with four-way switchable beams has been implemented on a planar substrate and evaluated for orthogonal four-way\nbeam steering performance with good agreement....
In this paper, we discuss the state of the art and trends in the field of smart clothing development and show two circuits\nthat we assembled in search for adequate solutions. The circuits are based on Arduino concept and achieve a full-duplex voice\ncommunication and real-time publishing of temperature measurement to a designated web page. The characteristics of the two\ncircuits are discussed as well as the prospects for their future improvements....
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