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The railroad industry in North America is heavily involved in improving the broadband wireless connectivity of their railroad operations. We propose our approach of establishing a Mobile WiMAX test bed as a part of our collaborations with the Federal Railroad Administration (FRA) for investigating the performance of current and upcoming broadband wireless technologies in a railroad environment. The...
Mobile WiMAX's scheduling service is a key factor in Radio Resource Management (RRM) in realizing Quality of Service (QoS). The choice in scheduling algorithm for Mobile WiMAX base stations, albeit outside of the scope of the standard, critically impacts the performance and robustness of Mobile WiMAX networks. This paper provides an in-depth study of four major scheduling algorithms: Round Robin (RR),...
In this paper, we present our approach of establishing a Mobile WiMAX test bed as a part of our collaborations with the Federal Railroad Administration (FRA) for studying the performance of current and upcoming broadband wireless technologies in a railroad environment. The focus is on studying the impact of mobility on the wireless system throughput for moving trains at high velocities. We describe...
Some theoretical and experimental models have been considered for the prediction of the path loss in mobile communication systems. This paper presents an alternative method to model the path loss characteristics, taking into account data analytical methods to discover dependency pattern among propagation model parameters. We applied the concept of nonlinear multi-regression to predict path losses...
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...
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,...
Several MAC protocols have been proposed for wireless sensor networks (WSNs). These include T-MAC, D-MAC and the more commonly utilized SMAC. In this paper, we propose a new MAC layer approach to support mobility in WSNs. The proposed technique utilizes an adaptive frame size approach to overcome the effect of frame losses caused by the Doppler shifts under mobile scenarios. An extended Kalman filter...
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