Abstract-In this paper, we present a RF directional modulation technique using a switched antenna array for physical layer secure communication. The main idea is that a switching scheme of the switched antenna array is designed according to a spreading sequence for the purpose of spreading spectrum of the transmit signal. The transmit signal is associated with the spreading sequence and the direction of the desired receiver because of information data modulated both in the baseband and the antenna level. In this way, the desired receiver with a single antenna can demodulate the receive signal as traditional spread-spectrum signal, while eavesdroppers can not extract any useful information from the receive signal even if eavesdroppers know the spreading sequence of the RF directional modulation signal.Simulation results show that the proposed technique offers a more secure transmission method for wireless communication comparison with traditional spread-spectrum signal.
Abstract-A RF directional modulation technique using a switched antenna array is proposed for communication and direction-finding applications. The main idea is that a baseband modulation signal is transmitted by the switched antenna array. The phase center of the transmit signal is moved by the feeding line of each element from the left to the right. In this way, the data information and Doppler frequency shift information are modulated into a transmit signal constellation simultaneously. Therefore, this constellation is a scrambled constellation compared with traditional baseband modulation signal, which varies with the azimuth angle information of the receiver. For the receiver with a single antenna, a differential correlation algorithm is employed to demodulate the data information, and an azimuth angle estimation algorithm is also developed to extract the azimuth angle information from this scrambled constellation. Simulation results show that this RF directional modulation technique offers a comprehensive scheme for communication and direction-finding from the point view of RF modulation technique.
Considering the three-dimensional (3D) trajectory, 3D antenna array, and 3D beamforming of unmanned aerial vehicle (UAV), a novel non-stationary millimeter wave (mmWave) geometry-based stochastic model for UAV to vehicle communication channels is proposed. Based on the analysis results of measured and ray tracing simulation data of UAV mmWave communication links, the proposed parametric channel model is constructed by a line-of-sight path, a ground specular path, and two strongest single-bounce paths. Meanwhile, a new parameter computation method is also developed, which is divided into the deterministic (or geometry-based) part and the random (or empirical) part. The simulated power delay profile and power angle profile demonstrate that the statistical properties of proposed channel model are time-variant with respect to the scattering scenarios, positions and beam direction. Moreover, the simulation results of autocorrelation functions fit well with the theoretical ones as well as the measured ones.
The pulse position detection of the pseudorandom time-hopping (TH) pseudolite is critical for the participative global navigation satellite system (GNSS) receivers. The conventional method to detect the pseudorandom TH pulse positions of the received pseudolite signal is mainly based on the exhaustive search of the matched TH intervals, which may cause low detection probability or even detection failure in relatively low signal to noise ratio (SNR) environments. With this problem, a new method to detect the TH pulse positions is given. The general process of the given method is that first the TH intervals derived from the correlation peaks of discontinuous direct sequence spread spectrum (DSSS) component are mapped to a code sequence, and then the mapped code sequence is circularly correlated in turn with each code sequence obtained from each group of TH slot indices of the TH table, finally by searching the maximum circular correlation peak, the TH slot indices of the received pseudolite signal and their initial phase will be found, further by combining them the work of TH pulse position detection is fulfilled. The simulation results show that with the given method, the detection probability and detection error of the obtained TH pulse positions can be greatly improved, hence the performance of the participative GNSS receivers will be enhanced.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.