Time filter

Source Type

Luan S.-Y.,Dalian University of Technology | Qiu T.-S.,Dalian University of Technology | Yu L.,Dalian University of Technology | Li J.-C.,The State Radio Monitoring Center | Tan H.-F.,Beijing University of Posts and Telecommunications
Dalian Ligong Daxue Xuebao/Journal of Dalian University of Technology | Year: 2014

A novel algorithm is proposed to locate the civil aviation ground interference source accurately and effectively via plane scattered signals. Firstly, a new method of arranging initial reference points is raised which is analyzed theoretically and testified experimentally. Secondly, correntropy and weighted centroid are introduced to optimize the existing locating algorithm. Both analyses and experiments are carried out. Simulation results show that the proposed algorithm improves the locating accuracy significantly and it has better practicality under equal amount of computations. ©, 2014, Dalian University of Technology. All right reserved.

Fu J.-Q.,Beijing University of Posts and Telecommunications | Li R.,The State Radio Monitoring Center | Zhao C.-L.,Beijing University of Posts and Telecommunications | Li B.,Beijing University of Posts and Telecommunications
Xi Tong Gong Cheng Yu Dian Zi Ji Shu/Systems Engineering and Electronics | Year: 2015

Under the time-varying fading channel, an adaptive modulation recognition algorithm is presented. A new dynamic state space model is designed to describe time-varying characteristics of modulation schemes and channel gain. A first-order finite state Markov channel (FSMC) model is introduced for the fading channel. On this basis, a new algorithm, which adopts the sequential Bayesian inference method and is proposed to fully exploit the dynamic transfer characteristics of the hidden channel state, achieves joint estimation of modulation and time-varying channel gain. The simulation results prove that performance of the algorithm compared to traditional ALRT algorithms greatly improves, and increasing the number of sampling points or reducing the Doppler shift value can make the performance better. © 2015, Chinese Institute of Electronics. All right reserved.

Li W.,The State Radio Monitoring Center | Zheng H.,Beijing University of Posts and Telecommunications | Qian Z.,The State Radio Monitoring Center | Li M.,The State Radio Monitoring Center
Nanjing Youdian Daxue Xuebao (Ziran Kexue Ban)/Journal of Nanjing University of Posts and Telecommunications (Natural Science) | Year: 2016

The candidate frequency bands of the future 5G mobile communication system in our country are 3.35, 4.9 and 5.4 GHz. However, the characteristics of the radio channel propagation in urban macro-cell scenario is rarely conducted at these bands. The channel measurement and the modelling are performed at 3.35, 4.9 and 5.4 GHz in typical outdoor macro-cell environment in Gaoling District of Xi'an. Utilizing Agilent E4438C signal source and Tek RSA6114 real time spectrum analyzer, the channel sounding system is established based on the spread spectrum correlation method. Some propagation parameters of these candidate bands in LOS and NLOS environments are obtained, such as path loss and root mean square delay spread. Field measurements show that the pass loss exponent of each candidate band matches well with the value in typical city environment. Compared with ITU M. 2135 model, the measurement model approximately agrees with ITU M. 2135 model in NLOS scenario, but has differences in LOS scenario. Root mean square delay spread of each candidate band follows Log-Normal distribution well. The study provides the theoretical foundation to evaluate the key technique for 5G, and benefits the wireless network planning and optimization of outdoor urban scenarios. © 2016, Periodical Office of Nanjing University of Posts and Telecommunications. All right reserved.

Ji W.,The State Radio Monitoring Center | Liu Z.,The State Radio Monitoring Center | Li L.,Beijing University of Posts and Telecommunications
Dianbo Kexue Xuebao/Chinese Journal of Radio Science | Year: 2013

Aiming at the problem of signal distortion and inter-wire coupling, the finite-difference time-domain (FDTD) method for nonuniform multiconductor transmission lines (MTL) is presented. Firstly, the simulation model for nonuniform MTL is discussed. Then, the voltage response of transmission line is analyzed using MATLAB programming. The results show that the FDTD method is correct and efficient for the electromagnetic compatibility (EMC), providing valuable reference for prediction of electromagnetic interference (EMI). Copyright © 2013 by Editorial Department of Chinese Journal of Radio Science.

Sun M.,Beijing University of Posts and Telecommunications | Li B.,Beijing University of Posts and Telecommunications | Song Q.,The State Radio Monitoring Center | Zhao L.,Beijing University of Posts and Telecommunications | Zhao C.,Beijing University of Posts and Telecommunications
IET Communications | Year: 2014

As the application scope of cognitive radio grows continuously, time-variant flat fading (TVFF) channels become common in practical spectrum sensing scenarios. Unfortunately, most existing spectrum sensing methods which are designed for time-invariant propagation channels could hardly obtain good performance when they operate in realistic TVFF channels. To combat this difficulty, in this investigation the authors design a promising spectrum sensing method. Firstly, a novel dynamic state-space model is proposed in which a two-state Markov chain is employed to abstract the evolution of primary user states and a finite-state Markov channel model is utilised to characterise the TVFF channel. Secondly, based on the maximum a posteriori probability criteria and the particle filtering mechanic, a joint estimation algorithm of the time-dependent fading channel gain and the state of primary user is presented. Experimental simulations verify the performance superiority of the authors presented joint detection scheme, which could be properly applied to spectrum sensing in realistic TVFF channels.

Liu Y.,Inner Mongolia University | Qiu T.-S.,Dalian University of Technology | Li J.-C.,The State Radio Monitoring Center
Tongxin Xuebao/Journal on Communications | Year: 2013

The problem of time delay estimation (TDE) for cyclostationary signals in the presence of a-stable distribution impulsive noise and interfering signals was addressed. Since the conventional algorithms based on the second-order cyclic spectral correlation function degenerated severely in impulsive noise environment, a novel robust algorithm based on the fractional lower-order spectrum was proposed. Compared with conventional spectra analysis methods, this novel method could suppress Gaussian noise, non-Gaussian impulsive noise and interfering signals more effectively. Simulation results demonstrate the effectiveness and robustness of the novel algorithm.

Zhao X.,North China Electrical Power University | Guo C.,North China Electrical Power University | Li J.,The State Radio Monitoring Center
Dianzi Yu Xinxi Xuebao/Journal of Electronics and Information Technology | Year: 2016

To recognize the major modulation schemes which are applied to concurrent communication systems, a joint method based on the high-order cumulants and cyclic spectrum with intelligent decision algorithm (neural network) is proposed to recognize the modulation schemes for digital signals. Firstly, a new featured parameter is extracted from the four-order and six-order cumulants of the digital signals to identify the modulation schemes of {BPSK, 2ASK}, {QPSK}, {2FSK, 4FSK}, {MSK}, and {16QAM, 64QAM}, then {OFDM}, {16QAM, 64QAM}, {2ASK, BPSK}, and {2FSK, 4FSK} are classified by the other featured parameters of the joint high-order cumulants and cyclic spectrum algorithms. In order to facilitate the engineering implementation, the semi-physical simulation and mixed programming of LabVIEW and MATLAB are used to validate the proposed algorithms. Simulation results show that the algorithms can recognize modulations {OFDM, BPSK, QPSK, 2ASK, 2FSK, 4FSK, MSK, 16QAM, 64QAM} with small Signal-to-Noise Ratio (SNR). The average recognition rate is more than 94% with SNR greater or equal than 5 dB, which validates the effectiveness of the proposed algorithms. © 2016, Science Press. All right reserved.

Chen Y.,Beijing Polytechnic | Li W.,The State Radio Monitoring Center | Hu Y.,Beijing Polytechnic | Zhu Q.,Beijing Polytechnic
Mobile Networks and Applications | Year: 2016

In two-tier heterogeneous networks (HetNets) that consist of a central macrocell underlaid with spectrum-sharing dense smallcells, one primary concern is the cross-tier interference limits the network capacity. On the other hand, dormancy mechanism of smallcells is an emerging technique that can improve energy efficiency and mitigate interference. Therefore in this paper, we propose a power optimization oriented Stackelberg game considering dormancy mechanism for the downlink of two-tier HetNets. First, the smallcell dormancy mechanism is introduced to control the smallcells’ operation. Then the Stackelberg game framework is developed. A sub game based on a potential theory is further formulated to optimize the transmit power of the active smallcells, which is demonstrated to converge to a pure and unique Nash equilibrium. In this sub game, the interference pricing mechanism is employed to price the cross-tier interference caused by smallcells and hence restricts the utility function of smallcells. Simulation results show that the proposed Stackelberg game based on dormancy mechanism with interference pricing can improve the smallcell network throughput and meanwhile reduce the average transmit power of smallcells. © 2016 Springer Science+Business Media New York

Shen J.-F.,The State Radio Monitoring Center
Tien Tzu Hsueh Pao/Acta Electronica Sinica | Year: 2014

This article researches the radio interference (RI) from the tower scattering of high-voltage power transmission line (HVPTL) to radio direction finding (DF) system. The theoretical simulation is verified by numerical analysis on the measured data. Two HVPTLs nearby a DF station were constructed. From the very beginning we started series tests based on the selected sites around the station. The analyzing and comparison of the test data shows that there is impact of the HVPTL to radio DF, the accuracy of the DF with spatial spectrum estimation is better than the one with correlative interferometer, which improved 1° and 0.5° in corresponding frequency band.

Xia N.,The State Radio Monitoring Center | Wei W.,The State Radio Monitoring Center | Li J.,The State Radio Monitoring Center | Zhang X.,The State Radio Monitoring Center
IET Signal Processing | Year: 2016

In this study, a non-linear filtering algorithm for state estimation with symmetric alpha-stable (SαS) noise is presented. The dynamic system model investigated here can be described by a linear state-space equation and a non-linear observation equation. The contribution of this study can be summarised as follows. First, particle filtering approach is employed for coarse estimation of the unknown parameters and then Kalman filter is performed to achieve better estimation. Second, SαS noise is considered as the additive disturbance in the observed signal and Gaussian approximation is used to compute the characteristics. Third, the calculation complexity is analysed according to the proposed algorithm. The proposed method is compared with the standard particle filter, extended Kalman filter and unscented Kalman filter for static parameter estimation of a periodic signal. As a practical application, the proposed method is used in high frequency source localisation based on time difference of arrival measurements. © The Institution of Engineering and Technology 2016.

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