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A Novel Collision Probability based Adaptive Contention Windows Adjustment for QoS Fairness on Ad Hoc Wireless Networks
Get PDFIt is crucial to achieve Quality of Service (QoS) on
IEEE802.11 in order to provide stable and reliable communication for real time and multimedia applications. Most of the recent QoS techniques for Ad Hoc Networks rely on basic QoS classifications such as Enhanced Distributed Channel Access (EDCA)and Hybrid Coordination Function Channel Access (HCCA) with stationary backoff range for specific services, without considering overall resource consumption and the external correlation among terminals. In this paper, a novel contention window adjustment QoS scheme, as a special case of QoS classification, is proposed for achieving QoS-fairness on Ad Hoc Networks. It applies dynamic automatic QoS assignment with low complexity by considering the restriction among various terminal requirements. Throughput estimation with a proportional relation between throughput and backoff parameters is discussed based on a Markov chain model
of a saturated Ad Hoc Networks. We measure the performance of different QoS algorithms theoretically and verify improvements of our algorithm on QoS-fairness with detailed simulations.TRUEpu
Networking 2012: Proceedings 11th International IFIP TC 6 Networking Conference, Prague, Czech Republic, 21 – 25 May, 2012
No full textTRUEpu
Brief Announcement: Achieving Reliability in Master-Worker Computing via Evolutionary Dynamics
Get PDFThis work considers Internet-based task computations in
which a master process assigns tasks, over the Internet, to
rational workers and collect their responses. The objective
is for the master to obtain the correct task outcomes. For
this purpose we formulate and study the dynamics of evolu-
tion of Internet-based master-worker computations through
reinforcement learning.TRUEpu
Denser networks for the Future Internet, the CROWD approach
Get PDFThis paper presents the key ideas behind the ICT CROWD
(Connectivity management for eneRgy Optimised Wireless Dense networks)project, funded by the European Commission. The project moves from the observation that wireless traffc demand is currently growing exponentially. This growing demand can only be satisfied by increasing the density of points of access and combining different wireless technologies. Mobile network operators have already started to push for denser, heterogeneous deployments; however, current technology needs to steer towards effciency, to avoid unsustainable energy consumption and network performance implosion due to interference. In this context,
CROWD promotes a paradigm shift in the future wireless Internet architecture, towards global network cooperation, dynamic network functionality configuration and fine, on demand, capacity tuning. CROWD pursues four key goals: (i) bringing density-proportional capacity where it is needed, (ii) optimising MAC mechanisms operating in very dense
deployments by explicitly accounting for density as a resource rather than as an impediment, (iii) enabling traffic-proportional energy consumption, and (iv) guaranteeing mobile user's quality of experience by designing smarter connectivity management solutions.TRUEpu
Enhancing orchestration of lab sessions by means of awareness mechanisms
Get PDFVol. 7563Orchestrating learning is a quite complex task. In fact, it has been identified as one of the grand challenges in Technology Enhanced Learning(TEL) by the Stellar Network of Excellence. The objective of this article is to provide teachers and students with a tool to help them in their effort of orchestrating learning, that makes use of awareness artefacts. Using this powerful mechanism in lab sessions, we propose four different aspects of orchestration as the target for improvement: the management of the resources in the learning environment; the interventions of the teacher and provision of formative feedback; the collection of evidences for summative assessment; and the re-design of the activity, adjusting some parameters for future enactments. The proposal has been tested in a real course of Multimedia Applications with
junior students (3rd course), measuring the benefits for the orchestration.TRUEpu
Loop-free convergence using oFIB
Get PDFThis document describes a mechanism for use in conjunction with link state routing protocols which prevents the transient loops which would otherwise occur during topology changes. It does this by correctly sequencing the FIB updates on the routers. This mechanism can be used in the case of non-urgent link or node shutdowns and restarts or link metric changes. It can also be used in conjunction with a fast re-route mechanism which converts a sudden link or node failure into a non-urgent topology change. This is possible where a complete repair path is provided for all affected destinations. After a non-urgent topology change, each router computes a rank that defines the time at which it can safely update its FIB. A method for accelerating this loop-free convergence process by the use of completion messages is also described. The technology described in this document has been subject to extensive simulation using real network topologies and costs, and pathological convergence behaviour.Internet Engineering Task Force (IETF)pu
A safe driver assisted merge protocol
No full textWe present a cooperative driving protocol that assists drivers in merging with other vehicles. We develop a modular architecture that is based upon the multiple hardware and communications platforms that must participate in this type of system. The architecture isolates the lower level functions related to the hardware from the application, and simplifies writing the merge protocol. We specify the protocol as an Extended Finite State Machine and validate it using Probabilistic Verification [1]. We demonstrate that for a wide range of hardware failures, communications failures, and unresponsive drivers, the protocol will not cause an accident. We also show that there may be situations with a very low probability, where the protocol will leave a vehicle in a state where it cannot participate in future merge operations without being reset.TRUEpu
Routing for Power Minimization in the Speed Scaling Model
Get PDFWe study network optimization that considers power minimization as an objective. Studies have shown that mechanisms such as speed scaling can significantly reduce the power consumption of telecommunication networks by matching the consumption of each network element to the amount of processing required for its carried traffic. Most existing research on speed scaling focuses on a single network element in isolation. We aim for a network-wide optimization. Specifically, we study a routing problem with the objective of provisioning guaranteed speed/bandwidth for a given demand matrix while minimizing power consumption. Optimizing the routes critically relies on the characteristic of the speed–power curve, which is how power is consumed as a function of the processing speed. If is superadditive, we show that there is no bounded approximation in general for integral routing, i.e., each traffic demand follows a single path. This contrasts with the well-known logarithmic approximation for subadditive functions. However, for common speed–power curves such as polynomials, we are able to show a constant approximation via a simple scheme of randomized rounding. We also generalize this rounding approach to handle the case in which a nonzero startup cost appears in the speed–power curve, We present an approximation, and we discuss why - oming up with an approximation ratio independent of the startup cost may be hard. Finally, we provide simulation results to validate our algorithmic approaches.TRUEpu