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OpenVLC: Software-Defined Open Architecture for Embedded Visible Light Networks
Get PDFThe goal of this demo is to introduce OpenVLC, a flexible software-defined platform for research on Visible Light Communication (VLC) networks. Built around a cost-effective embedded Linux platform with an LED front end, OpenVLC offers a set of essential physical layer (PHY) and medium access control (MAC) primitives, as well as an interface to Internet protocols. OpenVLC makes it possible to easily build PHY and MAC protocols and rapid prototype them in realistic network setups. In this demo, we show that OpenVLC can switch between different MAC protocols and can be employed jointly with standard TCP/IP diagnostic tools.TRUEpu
Reputation-Based Mechanisms for Reliable Crowdsourcing Computation
Get PDFWe consider an Internet-based Master-Worker framework, for machine-oriented computing tasks (i.e.
SETI@home) or human intelligence tasks (i.e. Amazon’s Mechanical Turk). In this framework a master sends
tasks to unreliable workers, and the workers execute and report back the result. We model such computations using
evolutionary dynamics and consider three type of workers: altruistic, malicious and rational. Altruistic workers
always return the correct result, malicious workers always return an incorrect result, and rational (selfish) workers
decide whether to be truthful depending on what increases their benefit. The goal of the master is reaching eventual
correctness, that is, a stable state of the system in which it always obtains the correct results. To this respect, we
propose a mechanism that uses reinforcement learning to induce a correct behavior to rational workers; coping with
malice leveraging reputation schemes. We analyze our system as a Markov chain and we give provable guarantees
under which truthful behavior can be ensured. Simulation results, obtained using parameter values similar to the
values observed in real systems, reveal interesting trade-offs between various metrics and parameters, such as cost,
time of convergence to a truthful behavior, tolerance to cheaters and the type of reputation metric employed.pu
On the implementation, deployment and evaluation of a networking protocol for VANETs: the VARON case
No full textResearch on vehicular communications has been quite extensive over the past few decades. Most of the initial studies were theoretical and research has just recently moved to more experimental works. Conducting real field
operational tests is extremely challenging due to the number of vehicles required, the lack of control over the environment and the cost of the necessary equipment and personnel. However, simulation tools may not reflect
properly the highly dynamic and complex characteristics of the vehicular scenario. This article explores why practical research in the field of vehicular communications is so demanding, by reporting on our experience in prototyping
and experimentally evaluating VARON. Published in 2008, VARON is a multi-hop wireless vehicular communication protocol which was already validated via extensive simulations. In this work, we have fully implemented
it, first on a lab-based environment, and then in a real-life testbed. This long and exhausting process has shown that some common assumptions do not necessarily hold when evaluated under real situations, as well as taught us
valuable lessons on how to design and conduct experiments with real vehicles. We believe that the experience and lessons learned during this process do not only apply to VARON, but also to other multi-hop wireless vehicular
communication solutions, and that therefore these lessons are helpful for other researchers willing to validate their protocols in a real scenario.pu
Energy-Efficient User Association In Extremely Dense Small Cell Networks
Get PDFDense heterogeneous networks constitute the paradigm for the future networks. In fact, recent studies demonstrate
that the data traffic demand increases exponentially and
the traditional cellular networks are not able to provide enough capacity. For this reason operators and standardisation bodies are particularly eager to solve the problem, hence there is a lot of ongoing research on this direction. In this paper we focus on extremely dense networks, that could be found, e.g., in crowded public places or in offices. In such deployments, energy
consumption must be kept proportional to the traffic dispatched, otherwise operational costs will render them unsustainable from an economic perspective. In this paper, we propose a network model for the estimation of the power consumption of an LTE dense network of small cells, which takes into account the backhaul network. Furthermore, we introduce a new mechanism for the association of the users to base stations, aiming at minimizing the energy consumption of the LTE access network. The achieved trade-off among capacity and power consumption is then evaluated by means of a classical association policy that
connects each user to the base station which received signal is the strongest.TRUEpu
LabVIEW based Platform for prototyping dense LTE Networks in CROWD Project
Get PDFhttp://dx.doi.org/10.1109/EuCNC.2014.6882658Next-generation wireless networks (5G) cope with significant traffic increase because of high-quality video transmission and cloud-based applications. This creates the need for a revolutionary change in architecture rather than a series of local and incremental technology updates. A dense heterogeneous deployment of small cells such as pico/femto cells in addition to high-power macro cells is a potential solution. In this area, a significant amount of research relies on simulations at PHY, MAC, and higher layers, but it is still necessary to validate the algorithms for next-generation systems in a real-time testbed. The ever-increasing complexity in all layers of current and future generations of cellular wireless systems, however, has made an end-to-end demonstration of the network limited to industrial research labs or large academic institutions. As a solution to tame the dense deployment of wireless networks, we propose an NI PXI platform based on NI LabVIEW software in which an LTE-like SISO OFDM PHY layer is integrated with an open-source protocol stack to prototype PHY/MAC cross layer algorithms within a CROWD (Connectivity management for eneRgy Optimised Wireless Dense networks) software-defined networking (SDN) framework.TRUEpu
Performance Analysis and Algorithm Selection for Reliable Multicast in IEEE 802.11aa Wireless LAN
No full textLegacy IEEE 802.11 does not efficiently support multicast transmissions. In order to cope with the increasing demand for multicast, mainly required to deliver multimedia traffic, the IEEE 802.11aa Task Group has recently standardized new mechanisms to allow efficient and robust transmission of multicast flows in Wireless LAN. However, the standard allows the use of different mechanisms for this purpose, and leaves open the choice of which one to use for a given scenario. In this paper, we present an analytical model to evaluate the performance of the mechanisms included in the 802.11aa standard and compare their performance. Our analysis shows that there is no absolute winner out of these mechanisms, and performance strongly depends on the scenario. Building on our model, we then propose a novel algorithm that selects the best multicast mechanism to use as a function of the scenario conditions. Our results are validated by extensive simulations.pu
Interference Coordination Strategies for Content Update Dissemination in LTE-A
Get PDFOpportunistic traffic offloading has been proposed to tackle overload problems in cellular networks. However, they only address the problem of deadline-based content propagation in the cellular system, given wireless environment characterization. In contrast, we cope with the traffic offloading issue from another perspective: the base station interference coordination problem. In particular, we aim at the minimization of the total transmission time spent by the base stations in order to inject contents into the network, and we leverage the recently proposed ABSF technique to keep under control intercell interference. We formulate an optimization problem, prove that it is NP-Complete, and propose a near-optimal heuristic. Our proposed algorithm substantially outperforms classical intercell interference approaches proposed in the literature, as we evaluate through the simulation of dense LTE-A network scenarios.TRUEpu
Using Tuangou to Reduce IP Transit Costs
Get PDFA majority of ISPs (Internet Service Providers) support connectivity to the entire Internet by transiting their traffic via other providers. Although the transit prices per decline steadily, the overall transit costs of these ISPs remain high or even increase, due to the traffic growth. The discontent of the ISPs with the high transit costs has yielded notable innovations such as peering, content distribution networks, multicast, and peer-to-peer localization. While the above solutions tackle the problem by reducing the transit traffic, this paper explores a novel approach that reduces the transit costs without altering the traffic. In the proposed CIPT (Cooperative IP Transit), multiple ISPs cooperate to jointly purchase IP (Internet Protocol) transit in bulk. The aggregate transit costs decrease due to the economies-of-scale effect of typical subadditive pricing as well as burstable billing: not all ISPs transit their peak traffic during the same period. To distribute the aggregate savings among the CIPT partners, we propose Shapley-value sharing of the CIPT transit costs. Using public data about IP traffic and transit prices, we quantitatively evaluate CIPT and show that significant savings can be achieved, both in relative and absolute terms. We also discuss the organizational embodiment, relationship with transit providers, traffic confidentiality, and other aspects of CIPT.pu
Modelling Throughput Prediction Errors as Gaussian Random Walks
Get PDFOne of the most critical aspects of anticipatory networking is assuming that future system conditions can be estimated. In this paper we address how accurate the current state of the art predictors are in providing a forecast of short term throughput. We propose a simple model for the short term prediction error based on Gaussian Random Walks that allows for mathematical analysis of the impact of imperfect future
knowledge on network optimization.TRUEpu
Graceful BGP session shutdown
Get PDFNetwork Working Group
Internet-Draft
Intended status: Informational
Expires: February 15, 2015This draft describes operational procedures aimed at reducing the amount of traffic lost during planned maintenances of routers or links, involving the shutdown of BGP peering sessions.Internet Engineering Task Force (IETF)pu