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Due to the scarcity of the licensed spectrum allocated for mobile communication systems, licensed-assisted access long-term evolution (LAA-LTE) network is recently proposed to deploy in unlicensed spectrum, which is currently occupied by different Wi-Fi systems. It is a very challenging problem to ensure fair coexistence between LAA-LTE and Wi-Fi networks, in terms of spectrum sharing and traffic...
While it is not a problem to implement large buffers in crosspoints nowadays, crosspoint queued (CQ) switch architecture has been recently implemented, which is a special buffered crossbar with large crosspoint buffers and no input queues. Under unicast traffic conditions, CQ nearly behaves as an ideal output-queued switch while the buffer size increases. Multicast is much more sophisticated that...
Cellular controlled Device-to-Device (D2D) system is a local service for future communication systems like LTE, LTE-A, etc. D2D communications can share the Uplink (UL) or Downlink (DL) resources with cellular communications to improve system throughput. Since reusing UL resource or DL resource has different merits in different scenarios, if D2D only reuses either UL or DL resource during the whole...
Inter-vehicle and roadside-to-vehicle communications can contribute to a safer and more efficient driving experience by providing time-sensitive and location-aware information. However, its performance suffers from vehicle mobility, intermittent user connectivity, and wireless channel unreliability. In this paper, we propose a novel cross-layer optimization approach based on our Adaptive Distributed...
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...
IEEE 802.16e-based Mobile WiMAX has gained considerable popularity recently. However, there is no current simulation model that provides feature completeness and performance accuracy. In this paper we propose the design and implementation methodology of a complete, accurate, realistic and versatile simulation model to support Mobile WiMAX for the NS-2 simulation platform. In the proposed simulation...
Recently, semiconductor industries have integrated more cores in a single die, which substantially improves the throughput of the processors running highly-parallel applications. However, many existing applications do not have high enough parallelism to exploit multiple cores in a die, slowing the transition to many-core processors with smaller and more cores that benefit future applications with...
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...
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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