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With the development of wireless communication, the characteristics of radio propagation become more and more important. Channel measurement and computer simulation are widely used in radio propagation research. For convenience, simulation based on FEKO was presented in this paper. The effect of frequency, antenna location, antenna height and conductivity on propagation characteristics in corridor...
According to the medium and long term development planning of railway networks, China will built “eight vertical and horizontal” high speed railway network during 13th five-year. With the rapid development of mobile smart terminals, the rail dedicated communication system using GSM-R system cannot satisfy the passengers' communication requirement. As high frequency communication has been considered...
Accurate network planning is critical with deployments of large outdoor wireless networks. Propagation and path loss considerations are key factors in predicting performance of wireless networks. We are currently studying large-scale wireless networks for US railway environments. In this study, both theoretical and measurement based propagation models indicate that the average received signal power...
Current propagation models used in network simulations neglect obstacles of a propagation environment and employ over-simplified assumptions that the received signal strength is a simple function of distance and the transmission area of a node is circular. These assumptions are in contradiction with the actual tests and the measurement results. To run reasonable simulations for evaluating the performance...
In wireless communications, packet size is one of the most significant parameters that have an impact on the quality of service (QoS). The optimal packet size depends on wireless channel condition and reception performance. However, it is difficult to determine the optimal packet size under time-varying channel in advance. Besides, performance characteristic of wireless devices is virtually unpredictable...
This paper presents a novel passive measurement approach to accurately evaluate the performance of outdoor multi- hop 802.11 networks from the wireless side directly. Our approach employs five processing steps to evaluate per-hop system performances. Firstly, reference packets are identified from multiple independent packet traces. Secondly, multiple packet traces in one channel are merged together...
With the steady development of WiMAX based broadband wireless access networks, complete and accurate simulation studies become crucial. In an effort to further improve our ns-2 simulation model for mobile WiMAX, we have implemented a selective repeat automatic retransmission request (SR-ARQ) mechanism into our model and evaluated its performance and accuracy. In this paper, we present the design and...
Because of the wide deployment of 802.11 equipments in the past decade, current applications are not limited anymore to only single access points (AP) deployments for indoor usage, but have been extended to multi-hop networks to fulfill the need of high speed connectivity in mobile environments, where the analysis of multi-hop networks is extremely complicated. The behavior of an AP is dependent not...
In this study we present our findings of important IEEE 802.16e-2005 performance characteristics. This study is part of our ongoing study of wireless communications technologies for the FRA and provides details about our approach to modeling various channel effects, such as Doppler shift and Rician fading, details of the effect of link quality conditions, expected throughput and distance characteristics,...
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