2022/3

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Energy Efficiency Optimization for D2D Underlay Communication in Distributed Antenna System over Composite Fading Channels
(Společnost pro radioelektronické inženýrství, 2022-09) Wang, G. Y.; Dhaka, A.; Teng, T.; Yu, K.
Device-to-Device (D2D) communication is a potential technology to improve the spectral and energy efficiency (EE) of communication networks. In this paper, we study energy-efficient power allocation (PA) schemes in uplink distributed antenna system (DAS) with device-to-device underlay communication. Our goal is to maximize the total EE of all D2D pairs while guaranteeing the data rate and transmit power requirements of the cellular user and D2D links. To solve this non-convex constrained optimization problem, we propose an energy-efficient near-optimal PA algorithm based on the concave-convex procedure and fractional programming theory. This near-optimal algorithm can achieve the EE performance close to the optimal exhaustive search. To reduce the complexity, we furthermore present an efficient sub-optimal algorithm with the antenna selection method which can obtain the closed-form power allocation expressions. Simulation results demonstrate the significant EE performance of our proposed PA schemes.
Spectrum Map Construction Based on Optimized Sensor Selection and Adaptive Kriging Model
(Společnost pro radioelektronické inženýrství, 2022-09) Ding, Z.; Zhang, J.; Liu, Y.; Wang, J.; Chen, G.; Cao, L.
Spectrum map (SM) is an important tool to reflect the spectrum usage in the electromagnetic environment. To address the problems of low precision and poor efficiency in the SM construction, this paper develops a novel SM construction approach based on the artificial bee colony enabled sensor layout optimization and an adaptive Kriging model based on spatial autocorrelation. Considering the significant autocorrelation between sensor attributes caused by the exponentially decaying shadow fading of signal propagation, the sensor estimation groups are established, and the estimation results are obtained by the Kriging model. The simulation results show that the proposed SM construction scheme can not only effectively reduce the overhead of sensor resources but also obtain a high SM construction accuracy. Extensive simulation results show that the proposed method can reduce the RMSE of SM construction by 37.56%, 25.32% and 12.89% respectively compared with Random-OK when the standard deviation of shadow fading is 1 dB, 3 dB and 6 dB.
Dual Band Microstrip Semicircular Slot Patch Antenna for WLAN and WIMAX Applications
(Společnost pro radioelektronické inženýrství, 2022-09) Mushtaq, M. T.; Shah, S. M. A.; Munir, S.; Hussain, M.; Iqbal, J.; Khan, U. H.
A dual band microstrip antenna for WIMAX and WLAN applications is analyzed and presented in this paper. The proposed antenna has semicircular slot in patch and Defected Ground Surface (DGS) technique for the improvement of its bandwidth and gain. Computer Simulation Technology (CST) software is used to design and simulate the performance characteristics. The proposed antenna has the dimensions as 28 x 26.6 mm2. The fabricated antenna provides a good reflection coefficient of -48dB and -44.5dB at a center frequency of 3.4GHz and 5.5GHz. Gain achieved by the antenna is 2.72dB and 3.87dB for WLAN and WIMAX application. Good agreements have been found between simulated and measured results. These results confirm that the fabricated antenna is very promising for WLAN and WIMAX applications.
An EMC Susceptibility Study of Integrated Basic Bandgap Voltage Reference Cores
(Společnost pro radioelektronické inženýrství, 2022-09) Krolak, D.; Horsky, P.
This paper presents a comparative EMC susceptibility study of various integrated bandgap voltage reference cores. Conventional well-known bandgap references based on Kuijk, Brokaw and Tsividis concepts with reduced count of bipolar junction transistors in the core were analyzed. On top of the EMC susceptibility comparison, basic parameters like temperature drift, sensitivity to an operational amplifier input offset and line regulation are also discussed. The influence of a collector leakage current compensation at high temperatures is investigated as well.
Least Perturbation Based Method of Multi-Objective Null Placement in Linear Antenna Array Using Evolutionary Algorithms
(Společnost pro radioelektronické inženýrství, 2022-09) Chatterjee, S.; Bandyopadhyay, B.; Chatterjee, S.; Majumdar, A.
The paper proposes a novel least perturbation based method of constrained null placement for a non-uniformly excited linear antenna array. Synthesis of am¬plitude and phase of edge element using least perturbation based analytical technique for required null placement leads to degradation of pattern in terms of increased side lobe level and beam broadening. Further computation capability of the method of least perturbation has been enhanced using an evolutionary algorithm. Subsequently, suitable evolutionary algorithms have been employed to find the optimum value of excitation and phase of edge elements subject to constraints of side lobe level reduction, beamwidth narrowing, and main beam control. Design of 8 and 15 elements linear array with a 95% reduction in com-putation time elucidates the capabilities of the proposed method. Further 3D electromagnetic solver -based valida¬tion process has been used to ascertain the practical acceptability of the method.

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