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Off-line incentive mechanism for long-term P2P backup storage
Get PDFThis paper presents a micro-payment-based incentive mechanism for long-term peer-to-peer storage systems. The main novelty of the proposed incentive mechanism is to allow users to be off-line for extended periods of time without updating or renewing their information by themselves. This feature is enabled through a digital cheque, issued by the user, which is later employed by the peers to get a gratification for storing the user’s information when the user is off-line. The proposed P2P backup system also includes a secure and lightweight data verification mechanism. Moreover, the proposed incentive also contributes to improve the availability of the stored information and the scalability of the whole system. The paper details the verification and cheque-based incentive mechanisms in the context of a P2P backup service and analyzes its scalability and security properties. The system is furthermore validated by means of simulation, proving the effectiveness of the proposed incentive.TRUEpu
Two-way relaying for multiple applications in wireless sensor networks
Get PDFRecent work in wireless sensor networks implies possibilities of concurrent support of multiple applications. In this paper, we discuss a novel scheme called hybrid computation in two-way relaying, which introduces cooperation of three sensor nodes to support bi-directional communications of two applications. Applications in wireless sensor networks require
different computations and forms of aggregation. In the proposed scheme, different computations at the intermediate node are integrated in a two-way relaying scheme. For computations and transmissions in the proposed scheme, data from all three nodes are considered. We propose a superposition coding protocol and a time division protocol to handle the transmission of the messages from the intermediate node. The problem of maximizing the sum rate is discussed. The results show that the superposition coding
protocol outperforms the time division protocol.TRUEpu
SOLOR: Self-Optimizing WLANs with Legacy-Friendly Opportunistic Relays
Get PDFCurrent IEEE 802.11 WLANs suffer from the well- known rate anomaly problem, which can drastically reduce network performance. Opportunistic relaying can address this problem, but three major considerations, typically considered separately by prior work, need to be taken into account for an efficient deployment in real-world systems: 1) relaying could imply increased power consumption, and nodes might be hetero- geneous, both in power source (e.g., battery-powered vs. socket- powered) and power consumption profile; 2) similarly, nodes in the network are expected to have heterogeneous throughput needs and preferences in terms of the throughput vs. energy consumption trade-off; and 3) any proposed solution should be backwards-compatible, given the large number of legacy 802.11 devices already present in existing networks.
In this paper, we propose a novel framework, Self-Optimizing, Legacy-Friendly Opportunistic Relaying (SOLOR), which jointly takes into account the above considerations and greatly improves network performance even in systems comprised mostly of vanilla nodes and unmodified access points. SOLOR jointly optimizes the topology of the network, i.e., which are the nodes associated to each relay-capable node; and the relay schedules, i.e., how the relays split time between the downstream nodes they relay for and the upstream flow to an access point. The results, obtained for a large variety of scenarios and different node preferences, illustrate the significant gains achieved by our approach. Its feasibility is demonstrated through test-bed experimentation in a realistic deployment.pu
Analysis of power saving and its impact on web traffic in cellular networks with continuous connectivity
Get PDFIn this work, we analyze the power saving and its impact on web traffic performance when customers adopt the continuous connectivity paradigm. To this end, we provide a model for packet transmission and cost. We model each mobile user’s traffic with a realistic web traffic profile, and study the aggregate behavior of the users attached to a base station by means of a processor-shared queueing system. In particular, we evaluate user access delay, download time and expected economy of energy in the cell. Our study shows
that dramatic energy saving can be achieved by mobile devices and base stations, e.g., as much as 70%–90% of the energy cost in cells with realistic traffic load and the considered parameter settings.TRUEpu
A Modular, Flexible and Virtualizable Framework for IEEE 802.11
Get PDFWireless networks are extensively deployed due to their low cost and configuration easiness. However, they are not adapted to the new services and applications that are increasingly demanded by users. Current implementation of the IEEE 802.11 specification is supported in hardware devices and software developments, but they do not provide the adaptability that would enhance user experience in next generation networks. In this paper, we present a new wireless framework, based on the one currently supported by the Linux stack: mac80211. This new framework, named mac80211++, has been tailored to improve MAC features in terms of: (i) modularity, by defining different 802.11 MAC services; (ii) flexibility, by enabling dynamic configurability of the 802.11 MAC; (iii) virtualization, by managing parallel independent 802.11 MACs accessing the same system resources.TRUEpu
Wireless Multi-Access Delivery for SVC-based Video Applications
Get PDFLecture Notes of the Institute for Computer Sciences, Social Informatics and Telecommunications Engineering, Volume 58. February 2013.
Book Title: Mobile Networks and Management
Book Subtitle: 4th International Conference, MONAMI 2012, Hamburg, Germany, September 24-26, 2012, Revised Selected Papers
Publisher: Springer Berlin Heidelberg
DOI: 10.1007/978-3-642-37935-2_10
Print ISBN: 978-3-642-37934-5
Online ISBN: 978-3-642-37935-2Optimized video delivery, Quality of Experience (QoE) and
customer satisfaction are key issues to be addressed by mobile network operators while providing next generation video services to their users. The sharp increase in video traffic, the diversity of video applications and the availability of advanced smart-phones create new challenges that require a closer cooperation between the different layers of the IP protocol stack. Specifically, in this paper we explore the combination of heterogeneous wireless access (3G and WiFi) with intelligent video transport mechanisms implemented at the core network. Experiments demonstrate that implementing Scalable Video Coding (SVC) awareness at the mobility anchors can greatly enhance the video delivery process, increasing the QoE perceived at the users while reducing the cost per bit carried over the wireless network. Leveraging our prior work on IP flow mobility, we conduct experimental tests of SVC-based applications and report the perceived QoE over a sample of 25 people. The results show that the combination of 3G and WiFi coverage enhance the video delivery close to locally played video streams.TRUEpu
Bisection (Band)Width of Product Networks with Application to Data Centers
Get PDFThe bisection width of interconnection networks has always been important in parallel computing, since it bounds the amount of information that can be moved from one side of a network to another, i.e., the bisection bandwidth. The problem of finding the exact bisection width of the multidimensional torus was posed by Leighton and has remained open for 20 years.
In this paper we provide the exact value of the bisection width of the torus, as well as of several d-dimensional classical parallel topologies that can be obtained by the application of the Cartesian product of graphs. To do so, we first provide two general results that
allow to obtain upper and lower bounds on the bisection width of a product graph as a function of some properties of its factor graphs. We also apply these results to obtain bounds for the bisection bandwidth of a d-dimensional BCube network, a recently proposed topology for data centers.TRUEpu
Knowledge is Power: Online Performance of Non-uniform Tasks in Fault-prone Environments
Get PDFConsider a system in which tasks of different execution times arrive continuously and have to be executed by a set of processors that are prone to crashes and restarts. In this work we explore the impact of parallelism and faults on the competitiveness of such a system. If the system had complete knowledge of future events and unbounded computation capability, it could make the best possible decisions and achieve optimal performance. Unfortunately, we
show that no parallel deterministic algorithm can be competitive against the optimal solution provided in the idealistic scenario, even with tasks of only two different execution times. On the positive side, we show that providing additional energy to the system, in the form of processor speed-scaling, it is possible to develop deterministic algorithms that compare in favour to the
optimal solution with complete knowledge. We identify thresholds on the speedup under which such competitiveness cannot be achieved by any deterministic algorithm and above which there exist competitive algorithms with small competitive ratio.Telematics EngineeringUniversidad Carlos III de Madrid, Spainpu
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 evolution of Internet-based master-worker computations through
reinforcement learning.TRUEpu
