2019/1
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Recent Submissions
- ItemSystem Level Design of RF Receivers Based on Non Linear Optimization and Power Consumption Models(Společnost pro radioelektronické inženýrství, 2019-04) Lolis, Luis H. A.; Stroski, Pedro N.; Lima, Eduardo G.This work presents a method to optimally distribute the block specifications in an RF receiver in order to reduce power consumption. The parameters are Gain (G), Noise Figure (NF) and Input Third Order Intercept Point (IIP3). The method is based on setting the signal quality per block at the output; Signal to Noise Ratio (SNR) for noise and Signal to Noise plus Distortion Ration (SNDR) for linearity. Both are limited in order to fulfill the sensitivity and intermodulation tests of a given standard. Non linear power models can be used as the method is based on heuristics associated with non linear optimization. First, random valid sets are tested "A" times, while the best candidate is chosen as starting point for a non linear optimization with bounds based on interior point algorithm. The process is repeated "B" times, and the best candidate is chosen. To validate the method, a direct-conversion receiver was dimensioned for the Long Term Evolution (LTE) and Bluetooth Low Energy (B-LE) standards. Two power models were used, labeled PM1 and PM2. First the LTE is considered. When compared to predetermined signal quality distributions, the method reduced the power consumption by 65% and 41%, considering PM1 and PM2, respectively. Then the B-LE is chosen with power PM2. This model is linear and has an analytical minimum derived in the literature. The optimization achieved a precision of 0.2% to the analytical minimum using A=1000 and B=15.
- ItemAntenna Selection and Power Allocation in Massive MIMO(Společnost pro radioelektronické inženýrství, 2019-04) Selvam, Paranche Damodaran; Vishvaksenan, Kuttathati SrinivasanThis paper explores the massive multiple-input multiple-output (Ma-MIMO) communication system possessing large number of antennas at the basestation (BS) serving multiple user terminal (UT) in single cell configuration. Due the large number of antennas at the BS, the RF chains used is also increasing with the increase in the total power consumption of the system such as circuit power consumption, filter, mixer and digital to analog converter power consumption. The main aim of this paper is to reduce the transmit power consumption with the proposed antenna selection and power allocation approach. Initially, the equal power is allocated to users to find the optimal number of antenna selection. Then for the number of antennas selected the optimal power allocation is derived to users. An algorithm is proposed to iteratively find the antenna selection and power allocation. The simulation is done to evaluate the average data rate and to find the optimal transmit power of the system.
- ItemHarvested Energy and Spectral Efficiency Trade-offs in Multicell MIMO Wireless Networks(Společnost pro radioelektronické inženýrství, 2019-04) Tien Ngoc Ha; Ha Hoang KhaThe paper focuses on designing precoding matrices in multi-cell multiple-input multiple-output (MIMO) simultaneous wireless information and power transfer networks (SWIPT) where the sets of users are selected for data transmission in each time slot and the unselected users are dedicated to energy harvesting. The precoding design for the SWIPT problem is formulated as a general multi-objective maximization problem, in which the sum-rate (SR) and sum harvested energy (SHE) are maximized simultaneously under the transmit power constraints. Since the objective function of the maximization problem is not concave in the design matrix variables, it is difficult to directly obtain the optimal solutions. To tackle this challenge, we recast the SR function into one more amenable by applying the connection between the minimum mean square error and achievable data rate. In addition, to deal with the non-concavity of the harvested energy function, we derive its concave minorant. Then, we develop an efficient iterative algorithm based on alternating optimization (AO) to obtain the optimal precoders. We also analyze the convergence and computational complexity of the proposed algorithm. Finally, by numerical simulation results we investigate the trade-offs between the SR and SHE.
- ItemResearch on Passive Troposcatter Location System(Společnost pro radioelektronické inženýrství, 2019-04) Liu, Zan; Chen, Xihong; Liu, QiangElectromagnetic (EM) wave of enemy radar propagated by troposcatter can be utilized for beyond line-of-sight (b-LoS) location. To provide theoretical basis for passive troposcatter location system, channel characteristics including propagation loss, refraction effect and multipath fading are analyzed. Ray tracing method improved by tropospheric model is employed to describe the refraction effect. Correlation coefficient on the basis of transfer function is deduced to evaluate multipath fading. According to troposcatter characteristics, maximum operating range is estimated, cooperative energy detection is introduced to copy with the received signal without priori knowledge. The principle and accuracy of location algorithm based on azimuth is researched. Spatial smoothing is introduced under the situation that uncorrelated and coherent signals coexist. Through analyzing consequences, future directions for developing are suggested.
- ItemCyclostationary Feature Detection Based Blind Approach for Spectrum Sensing and Classification(Společnost pro radioelektronické inženýrství, 2019-04) George, Gemi Rachel; Prema, Samuel ChrisA Spectrum Sensing (SS) device, regardless of its location, should be able to detect the presence of signal over noise. In certain applications, SS should be able to correctly identify and classify the received signal. These functions are to be performed with little or no prior information about the incoming signal or channel noise. Cyclostationary Feature Detection (CFD) can be used to detect primary users (PU) using periodicity in autocorrelation of the modulated signals. These algorithms attempt to differentiate signal from noise based on the uncorrelated nature of noise. CFD is often considered as a semi-blind approach, since it requires prior information about the PU signal for detection. For identification and classification of PU signal, existing algorithms make use of CFD and neural networks. This paper proposes a novel algorithm to obtain completely blind detection performance based on CFD. Classification of PU signals is based on the basic statistics regarding cyclic spectrum. Further, an algorithm is formulated to identify modulation scheme of the signal and classify it without making use of any training algorithms. The proposed approach is capable of detecting PU reliably for SNR as low as –8 dB with no prior information about PU or noise in the channel.