2018/3

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Digital Predistorter Design Using a Reduced Volterra Model to Linearize GaN RF Power Amplifiers
(Společnost pro radioelektronické inženýrství, 2018-09) Rezgui, Haithem; Rouissi, Fatma; Ghazel, Adel
In this paper, a novel method for reducing a Simplified Volterra Series (SVS) model size is proposed for GaN RF Power Amplifier (PA) Digital Predistorter (DPD) design. Using the SVS-modified model, the number of coefficients needed for the PA behavioral modeling and predistortion can be reduced by 60 % while maintaining acceptable performances. Simulation and implementation tests are performed for a Class AB GaN PA and Doherty GaN PA using a 20-MHz Long Term Evolution-Advanced (LTE-A) signal. The Adjacent Channel Power Ratio (ACPR) attains -40 dB and -41 dB for the Doherty and Class AB GaN PAs, respectively. The implementation complexity is also studied and the obtained results prove the capability of the proposed model to linearize PA using 3% of the Slice LUTs and 87% of the DSP48E1 available in the Xilinx Zynq-7000 FPGA.
RE-HARP: RF Energy Harvesting MAC Protocol to Prolong Life Time of CRSNs
(Společnost pro radioelektronické inženýrství, 2018-09) Wasif, Sardar; Ishtiaq, Ahmad; Waseem, Nazar
Energy drainage is a critical issue in sensor networks which is aggravated further by the incorporation of Cognitive Radio (CR). Radio Frequency Energy Harvesting (RF-EH) is a prominent method for mitigating energy constraints while providing potentially perpetual lifetime. However, its inclusion in Cognitive Radio Sensor Networks (CRSNs) instigates various Medium Access Control (MAC) layer challenges. Effective communication in a way to avoid collisions in the presence of multiple Primary Users (PUs) and CR nodes willing to access electromagnetic spectrum and EH are the significant challenges. In this paper, a MAC protocol for CRSNs which overcome challenges above is proposed. In our protocol, the CR nodes use Dedicated Common Control Channel (DCCC) for control information exchange among CR nodes and Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol to access channel and avoid collisions. RF-EH technique is also incorporated to prolong the network lifetime. The proposed work is a state of the art MAC protocol in which CR nodes can communicate and harvest energy as well. Performance of the proposed protocol is evaluated in terms of throughput, harvested energy and lifetime of CRSNs by considering different parameters which include PU activities, number of CR nodes, number of flows and packet size. Simulations are performed on Network Simulator (NS-2).
A New Target Radar Cross Section Based Passive Radar Surveillance Receiver Positioning Algorithm on Real Terrain Maps
(Společnost pro radioelektronické inženýrství, 2018-09) Tuysuz, Burak
Placing surveillance receivers on passive radar systems is a complex task because of the dependence on third party vendors. This paper presents an efficient and robust algorithm for positioning passive radar surveillance receivers for the intended coverage based on the available transmitters of opportunity in the area. First, by using the topology maps of the area of interest, depending on the expected targets and available transmitters, visibility maps of the terrain is generated with a line of sight algorithm. Then, in terms of the position and the orientation of the targets, the bistatic radar cross sections are determined. Finally, based on the bistatic radar cross sections of the targets, antenna characteristics, visibility analysis and received power levels, the optimum location for the surveillance receiver and the best transmitter of opportunity to be employed is decided. A practical scenario by using frequency modulation radio is realized in the manuscript for the rapid deployment of a mobile passive radar system. It is shown that on a terrain with multiple transmitters, depending on the characteristics of the transmitters and intended coverage, an optimum location for the surveillance receiver can be found for rapid deployment.
A Non-Uniform-Angular-Rate Beam-Scan Method for Airborne TOPS Mode
(Společnost pro radioelektronické inženýrství, 2018-09) Guan, Yifu; Chang, Wenge
TOPS (Terrain Observation by Progressive Scans) mode can achieve large scene coverage through the beam-scan in a uniform-angular-rate form, when the scanning angle is large, the variation of azimuth theoretical resolution with the scanning angle cannot be ignored. Aiming at airborne SAR (Synthetic Aperture Radar) system, the Doppler characteristic of azimuthal echo of the TOPS mode with large scanning angle is analyzed, and a non-uniform-angular-rate beam-scan method is proposed. By adjusting the angular rate of the beam-scan in a real-time form, we can achieve a consistent azimuth theoretical resolution for the targets at different azimuth location. The simulation results show that the proposed method can alleviate the azimuth resolution inconsistency of about 0.4 m when the azimuth theoretical resolution is 5 m.
New Box Particle Filter with Improved Resampling Method and Extended Inclusion Volume Criteria for Multi-target Tracking
(Společnost pro radioelektronické inženýrství, 2018-09) Chen, Nanqi; Ji, Hongbing; Gao, Yongchan; Yang, Dan
In the resampling procedure of traditional box particle filtering, selected box particles are divided in a randomly chosen dimension. This resampling procedure may fail when some elements in the target state vector are unmeasured. To deal with this problem, an improved resampling method for box particle filtering is proposed, where a limit on the sizes of box particles is imposed to restrain the box particles from growing too large. In addition, we extend the inclusion and volume criteria from single-target tracking to multi-target tracking. Instead of indicating whether the true target state is included in the support of the posterior track probability in single target tracking, the inclusion value in multi-target tracking indicates how many true targets are included in the supports of the posterior probability densities. And the volume value in multi-target tracking is redefined as the mean volume of the supports of the posterior probability densities. Simulation results are provided to illustrate the effectiveness of the proposed approach.

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