60,716 research outputs found
Seamless Infrastructure independent Multi Homed NEMO Handoff Using Effective and Timely IEEE 802.21 MIH triggers
Handoff performance of NEMO BS protocol with existent improvement proposals
is still not sufficient for real time and QoS-sensitive applications and
further optimizations are needed. When dealing with single homed NEMO, handoff
latency and packet loss become irreducible all optimizations included, so that
it is impossible to meet requirements of the above applications. Then, How to
combine the different Fast handoff approaches remains an open research issue
and needs more investigation. In this paper, we propose a new Infrastructure
independent handoff approach combining multihoming and intelligent
Make-Before-Break Handoff. Based on required Handoff time estimation, L2 and L3
handoffs are initiated using effective and timely MIH triggers, reducing so the
anticipation time and increasing the probability of prediction. We extend MIH
services to provide tunnel establishment and switching before link break. Thus,
the handoff is performed in background with no latency and no packet loss while
pingpong scenario is almost avoided. In addition, our proposal saves cost and
power consumption by optimizing the time of simultaneous use of multiple
interfaces. We provide also NS2 simulation experiments identifying suitable
parameter values used for estimation and validating the proposed mode
Throughput optimization strategies for large-scale wireless LANs
Thanks to the active development of IEEE 802.11, the performance of wireless local area networks (WLANs) is improving by every new edition of the standard facilitating large enterprises to rely on Wi-Fi for more demanding applications. The limited number of channels in the unlicensed industrial scientific medical frequency band however is one of the key bottlenecks of Wi-Fi when scalability and robustness are points of concern. In this paper we propose two strategies for the optimization of throughput in wireless LANs: a heuristic derived from a theoretical model and a surrogate model based decision engine
South Atlantic continental margins of Africa: a comparison of the tectonic vs climate interplay on the evolution of equatorial west Africa and SW Africa margins
The comparative review of 2 representative segments of Africa continental
margin: the equatorial western Africa and the SW Africa margins, helps in
analysing the main controlling factors on their development. Early Cretaceous
active rifting S of the Walvis Ridge resulted in the formation of the SW Africa
volcanic margin. The non-volcanic rifting N of the Walvis ridge, led to the
formation of the equatorial western Africa margin, with thick and extensive,
synrift basins. Regressive erosion of SW Africa prominent shoulder uplift
accounts for high clastic sedimentation rate in Late Cretaceous - Eocene, while
dominant carbonate production on equatorial western Africa shelf suggests
little erosion of a low hinterland. The early Oligocene climate change had
contrasted response in both margins. Emplacement of the Congo deep-sea fan
reflects increased erosion in equatorial Africa, under the influence of wet
climate, whereas establishment of an arid climate over SW Africa induced a
drastic decrease of denudation, and thus reduced sedimentation on the margin.
Neogene emplacement of the African superswell beneath S. Africa renewed onshore
uplift on both margins, but it accelerated erosion only in the Congo catchment,
due to wetter climate. Neogene high sedimentation rate reactivated
gravitational tectonics that had remained quiescent since late Cretaceous
Hybrid solutions to the feature interaction problem
In this paper we assume a competitive marketplace where the features are developed by different enterprises, which cannot or will not exchange information. We present a classification of feature interaction in this setting and introduce an on-line technique which serves as a basis for the two novel <i>hybrid</i> approaches presented. The approaches are hybrid as they are neither strictly off-line nor on-line, but combine aspects of both. The two approaches address different kinds of feature interactions, and thus are complimentary. Together they provide a complete solution by addressing interaction detection and resolution. We illustrate the techniques within the communication networks domain
DReAM: An approach to estimate per-Task DRAM energy in multicore systems
Accurate per-task energy estimation in multicore systems would allow performing per-task energy-aware task scheduling and energy-aware billing in data centers, among other applications. Per-task energy estimation is challenged by the interaction between tasks in shared resources, which impacts tasksâ energy consumption in uncontrolled ways. Some accurate mechanisms have been devised recently to estimate per-task energy consumed on-chip in multicores, but there is a lack of such mechanisms for DRAM memories. This article makes the case for accurate per-task DRAM energy metering in multicores, which opens new paths to energy/performance optimizations. In particular, the contributions of this article are (i) an ideal per-task energy metering model for DRAM memories; (ii) DReAM, an accurate yet low cost implementation of the ideal model (less than 5% accuracy error when 16 tasks share memory); and (iii) a comparison with standard methods (even distribution and access-count based) proving that DReAM is much more accurate than these other methods.Peer ReviewedPostprint (author's final draft
Combining Bluetooth Mesh and KNX : the best of both worlds
Bluetooth Mesh (BT Mesh) is a promising wireless technology for building automation. At the same time, KNX is a well-established building automation system that has a vast installed base. Specifically, the strength of KNX lies in its proven semantic models. These models are the foundation for interoperability and the implementation of larger systems. The presented project demonstrates how a user can easily connect a new BT Mesh system to a well-established, wired KNX building automation system. Notably, the project achieves this through a self-developed stateless gateway, which allows controlling BT Mesh devices from the KNX network and vice versa. As a result, it is possible to leverage existing management systems from KNX building automation systems in BT Mesh networks. Furthermore, the project validates this concept using Home Assistant, a well- known open-source home automation platform and demonstrates, that heterogeneous KNX and BT Mesh systems are feasible
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