Urban Area Propagation Path Loss Reduction by Dynamic Differential Evolution Algorithm

[[abstract]]In the wireless outdoor communication, the buildings in modern cities to make the outdoor communication more difficult. In this paper, we propose the shooting and bouncing ray/image (SBR/Image) method to compute the path loss for outdoor environments in the commercial area of New Taipei. Three types of antenna arrays such as L shape, Y shape, and circular shape arrays are considered. Moreover, dynamic differential evolution algorithm (DDE) is employed to optimize the excitation voltages and phases for these antenna arrays to reduce the path loss and compare with the genetic algorithm (GA). The GA and DDE optimization is applied to a high order nonlinear optimization problem. By the obtained antenna patterns, we can find the route with the lowest path loss; meanwhile, transmission power using this route in the base station can be reduced. Numerical results show that the performance in reduction of path loss. The DDE algorithm outperforms the GA for proposed antenna arrays. The investigated results can improve design of outdoor communication system.[[conferencetype]]國際[[conferencedate]]20140423~20140425[[conferencelocation]]Taipei, Taiwa

Path Loss Reduction for Multiusers by Different Antenna Arrays

[[abstract]]In this paper, we use the shooting and bouncing ray/image (SBR/Image)[1]-[5] method to compute the path loss for different outdoor environments. Three types of antenna arrays such as L shape, Y shape, and Circular shape arrays are used in the base station and their corresponding path loss on several routes in the outdoor environment are calculated[6]-[8]. Moreover, the genetic algorithm (GA) and Dynamic Differential Evolution (DDE) are employed to optimize the excitation voltages and phases for antenna arrays to form proper antenna patterns[9], [10]. The particle swarm optimization algorithm has better optimization result than genetic algorithm in NLOS case. For antenna arrays Y shape has better optimization result in NLOS case.[[conferencetype]]國際[[conferencedate]]20140714~20140718[[conferencelocation]]Arusha, Tanzani

Propagation studies at 5.8 GHZ within vegetated environment for point-to-multipoint applications

This thesis presents an empirical study for fixed wireless links based on IEEE802.16 standard in vegetated residential environment. Simulation and field measurements were conducted for suburban microcell channel by utilising 5.8 GHz of Unlicensed National Information Infrastructure (UNII). A set of comprehensive measurement that covered 13 point-to-multipoint links surrounding Universiti Teknologi Malaysia were selected to investigate the impact of vegetation on propagating radio waves. The aim of this study is to develop a path loss model that incorporates vegetation effect. Received Signal Strength (RSS), Signal-to-Noise Ratio (SNR) and factors influencing performance of the signal strength are highlighted here. Performance of RSS during daytime and night is also evaluated. The accuracy of proposed prediction model is analysed which quantifies that path loss is proportional to the distance of tree to the receiver, size, density and number of trees within the vicinity of transmitting and receiving antennas. Observation found that terrain and external effect, such as wind will significantly affect the signal performance too. Depending on the dynamic characteristics of trees presence between the communication links, the measurement results show that the path loss is increased from 5.69 dB to 33.67 dB. The results obtained are compared to Free Space Loss model, Weissberger model, and ITU-R model. Those established models are used to validate the applicability result obtained by means of Root Mean Square Error (RMSE). In view of this research work, a good agreement of the proposed excess loss model achieves the smallest RMSE for links obstructed by a single tree, row of trees, row of trees and road as well as row of trees, road and building

Estudo da perda de percurso e do perfil de atraso de potências na frequência de 3500 MHz em regiões urbanas densamente vegetadas

O crescente número de dispositivos conectados à internet, aliado à necessidade de uma rede mais segura, rápida e com capacidade para bilhões de dispositivos conectados, serviram de base para o desenvolvimento do 5G. Um dos fatores que determina o bom desempenho de uma rede de telefonia móvel é o conhecimento do canal de rádio móvel em que se deseja transmitir. Para isso, nesse trabalho, foram realizadas simulações na frequência 3500 MHz, uma das faixas destinadas para operação o serviço 5G/LTE, na cidade de João Pessoa, Brasil, visando a obtenção de alguns dos principais parâmetros de caracterização do canal: a perda de percurso, situação de visada (LOS e NLOS), a distribuição de potência na região e o perfil de atraso de potências. A região de estudo é caracterizada por possuir densas e extensas áreas de vegetação e construções bastante heterogêneas. Foi utilizado nas simulações o Modelo de Traçado de Raios Inteligente (IRT) e os resultados obtidos mostram a forte influência da vegetação e da obstrução no sinal transmitido, apresentando maiores espalhamentos de retardo nas componentes recebidas, atenuações e forte redução na banda de coerência nos pontos mais afetados pela vegetação

Unapređenje metoda merenja fedinga u RF telemetrijskim sistemima srednje naponskih distributivnih mreža

In this paper, the estimation of Nakagami-m short term fading severity parameter and signal envelope average power are considered. Two methods enabling calculation severity parameter of Nakagami-m fading and are average power of signal envelope propagation in Nakagami-m fading channel by using measured values samples of Nakagami-m random process is considered in this work. By using measured values moments of Nakagami-m random process can be calculated. Nakagami-m fading parameters can be evaluated from moments. In this paper is considered the case when fading parameters are calculated from the second moment and the forth moment. Also, the case when Nakagami-m parameters are calculated by using the first, the second and the three moment is studied. In this paper diversity technique is applied for evaluation Nakagami-m fading parameters by using method of moments. Used diversity technique has MRC (maximal ratio combining) receiver with two and three inputs operating over independent and identical multipath fading channel. Moments of MRC receiver output signal enable Nakagami-m fading parameters evaluation. The accuracy of obtained results increases as the number of samples increases, the order of diversity increases and when the number of realizations increases. The second method studied in this paper, for estimating the Nakagami-m fading severity parameter and average power of Nakagami-m fading signal envelope is level crossing method. Level crossing rate is calculated for three values of signal envelope and from these three equations evaluated Nakagami-m parameters. Obtained expressions for level crossing rate are simple and Nakagami-m parameters can be determined. MRC diversity technique is applied for the estimation of Nakagami-m fading severity parameter and Nakagami-m signal envelope average power. The accurately of calculated values for Nakagami-m parameters increases as the number of samples increases, the number of realization increases and MRC diversity order increases. Also the accurately of obtained reports is higher for lower values of Nakagami-m fading severity parameter. *Application diversity technique for estimation of Nakagami-m fading parameters by using the method moments is not considered in open technical literature. *Level crossing rate method for estimation of Nakagami-m fading parameters is not considered in open technical literature