Misbehavior Detection in the Internet of Things: A Network-Coding-aware Statistical Approach

In the Internet of Things (IoT) context, the massive proliferation of wireless devices implies dense networks that require cooperation for the multihop transmission of the sensor data to central units. The altruistic user behavior and the isolation of malicious users are fundamental requirements for the proper operation of any cooperative network. However, the introduction of new communication techniques that improve the cooperative performance (e.g., network coding) hinders the application of traditional schemes on malicious users detection, which are mainly based on packet overhearing. In this paper, we introduce a non-parametric statistical approach, based on the Kruskal-Wallis method, for the detection of user misbehavior in network coding scenarios. The proposed method is shown to effectively handle attacks in the network, even when malicious users adopt a smart probabilistic misbehavior

A BRIEF REVIEW: NEUROMUSCULAR FUNCTIONS OF COMBAT SPORTS DURING DIFFERENT TYPES OF JUMPS

The aim of this research is to study the effect of different jumping types on vertical jumps, between athletes of different combat sports and non-athletes. The jump types investigated were squat jump (SJ), countermovement jump (CMJ) and drop jump (DJ), where in the latter case we distinguished two different height distances (20 cm and 40 cm). The neuromuscular activation of the athletes shows better neuromuscular coordination and greater maturation than non-athletes. Although vertical jumping ability is not consistent with the technique of a combat sports athlete, however, it can be a powerful reference factor at the level of athletes when combined with individual power indices.  Article visualizations

Energy sharing and trading in multi-operator heterogeneous network deployments

© 2020 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.With a view to the expected increased data traffic volume and energy consumption of the fifth generation networks, the use of renewable energy (RE) sources and infrastructure sharing have been embraced as energy and cost-saving technologies. Aiming at reducing cost and grid energy consumption, in the present paper, we study RE exchange (REE) possibilities in late-trend network deployments of energy harvesting (EH) macrocell and small cell base stations (EH-MBSs, EH-SBSs) that use an EH system, an energy storage system, and the smart grid as energy procurement sources. On this basis, we study a two-tier network composed of EH-MBSs that are passively shared among a set of mobile network operators (MNOs), and EH-SBSs that are provided to MNOs by an infrastructure provider (InP). Taking into consideration the infrastructure location and the variety of stakeholders involved in the network deployment, we propose as REE approaches 1) a cooperative RE sharing, based on bankruptcy theory, for the shared EH-MBSs and 2) a non-cooperative, aggregator-assisted RE trading, which uses double auctions to describe the REE acts among the InP provided EH-SBSs managed by different MNOs, after an initial internal REE among the ones managed by a single MNO. Our results display that our proposals outperform baseline approaches, providing a considerable reduction in SG energy utilization and costs, with satisfaction of the participant parties.Peer ReviewedPostprint (author's final draft

Internet Service Providers vs. Over-the-Top Companies Friends or Foes?

The recent appearance of Over-the-Top (OTT) providers, who offer similar services (e.g., voice and messaging) to those of the existing Internet Service Providers (ISPs), was the main reason for a long-standing conversation with regard to the network neutrality, i.e., the prioritization of different types of data in the network. In particular, ISPs oppose network neutrality, claiming that OTT companies: (i) have conflicting interests and provide competitive services, thus constituting a threat to their own growth, and (ii) distort incentives for investment, as they essentially exploit the network already deployed by ISPs, acting as free riders. The importance of the net neutrality debate has motivated the research community to study the interaction among the different tenants from a theoretical point of view [1,2]. Despite the interesting theoretical conclusions of the existing works, an empirical econometric study on the interaction of the new stakeholders was not possible hitherto, as the main evolution of the OTT companies took place at the end of the last decade and, therefore, real economic data from the actual progress of these firms were not available until recently. In this article, we provide a detailed econometric study to analyze the relationship between the OTT companies and the ISPs. The empirical analysis has been conducted for seven countries in the period 2008-2013, considering ten major ISPs and three OTT companies that offer communication services (i.e., Skype, Facebook and WhatsApp), while we focus on five different parameters: (i) the revenues of the ISPs, (ii) the revenues of the OTT providers, (iii) the Capital Expenditure (CAPEX) of the ISPs, (iv) the Internet penetration, and (v) the real Gross Domestic Product (GDP) that determines the economic performance of each country. For the analysis of our cross-sectional time series (countries and year) panel data, we propose two econometric models (based on the fixed effects model) with two different dependent variables: (i) Model A with the ISP revenues as the dependent variable and (ii) Model B with the OTT revenues as the dependent variable. The interpretation of the results of Model A reveals two very intriguing insights. First, we see that the revenues of the ISPs and the OTT companies are positively correlated with a particular coefficient of 9.81, i.e., the increase of one unit (e.g., USD) in the revenue of the OTT providers causes an average increase of approximately ten units in the revenues of ISPs. Second, the CAPEX of the ISPs has also a positive effect in their revenue with a coefficient of 3.21. The positive correlation between the revenues of the OTT companies and the ISPs is also verified in Model B with a coefficient of 0.03, which implies that the growth of ISPs has a positive (although small) impact on the growth of OTT providers. However, the most important conclusion that can be extracted by Model B is the negative impact that the CAPEX has on the OTT profits. More specifically, the revenue of the OTT companies is reduced by 0.13 units for every unit that the ISPs invest on the network infrastructure. The observations of our empirical analysis are very important, as they provide tangible arguments and answers to the claims of the net neutrality opponents. In particular, our study has shown that the economic prosperity of the OTT firms has a positive influence in the financial performance of the ISPs. Consequently, it can be concluded that these two important stakeholders fruitfully coexist in the telecommunications and Internet market and they should probably work more closely together to achieve a mutually profitable cooperation. In addition, our empirical results have also demonstrated that the network investments have a positive effect on the ISPs revenue and a negative impact on the revenue of the OTT providers, thus refuting the accusations towards OTT companies for free riding. Finally, although not exhaustive, our study stresses the need for additional similar studies that will further clarify the interaction among the different entities in the evolving Internet ecosystem.Grant numbers : This work has been supported by the research projects Cell-Five (TEC2014-60130-P) and AGAUR the Catalan Government 2014-SGR-1551 (2014-SGR-1551)

Game-theoretic infrastructure sharing in multioperator cellular networks

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The introduction of fourth-generation wireless technologies has fueled the rapid development of cellular networks, significantly increasing the energy consumption and the expenditures of mobile network operators (MNOs). In addition, network underutilization during low-traffic periods (e.g., night zone) has motivated a new business model, namely, infrastructure sharing, which allows the MNOs to have their traffic served by other MNOs in the same geographic area, thus enabling them to switch off part of their network. In this paper, we propose a novel infrastructure-sharing algorithm for multioperator environments, which enables the deactivation of underutilized base stations during low-traffic periods. Motivated by the conflicting interests of the MNOs and the necessity for effective solutions, we introduce a game-theoretic framework that enables the MNOs to individually estimate the switching-off probabilities that reduce their expected financial cost. Our approach reaches dominant strategy equilibrium, which is the strategy that minimizes the cost of each player. Finally, we provide extensive analytical and experimental results to estimate the potential energy and cost savings that can be achieved in multioperator environments, incentivizing the MNOs to apply the proposed scheme.Peer ReviewedPostprint (author's final draft

Multiobjective auction-based switching-off scheme in heterogeneous networks: to bid or not to bid?

©2016 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.The emerging data traffic demand has caused a massive deployment of network infrastructure, including Base Stations (BSs) and Small Cells (SCs), leading to increased energy consumption and expenditures. However, the network underutilization during low traffic periods enables the Mobile Network Operators (MNOs) to save energy by having their traffic served by third party SCs, thus being able to switch off their BSs. In this paper, we propose a novel market approach to foster the opportunistic utilization of the unexploited SCs capacity, where the MNOs, instead of requesting the maximum capacity to meet their highest traffic expectations, offer a set of bids requesting different resources from the third party SCs at lower costs. Motivated by the conflicting financial interests of the MNOs and the third party, the restricted capacity of the SCs that is not adequate to carry the whole traffic in multi-operator scenarios, and the necessity for energy efficient solutions, we introduce a combinatorial auction framework, which includes i) a bidding strategy, ii) a resource allocation scheme, and iii) a pricing rule. We propose a multiobjective framework as an energy and cost efficient solution for the resource allocation problem, and we provide extensive analytical and experimental results to estimate the potential energy and cost savings that can be achieved. In addition, we investigate the conditions under which the MNOs and the third party companies should take part in the proposed auction.Peer ReviewedPostprint (author's final draft

Connectivity analysis in clustered wireless sensor networks powered by solar energy

©2018 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.Emerging 5G communication paradigms, such as machine-type communication, have triggered an explosion in ad-hoc applications that require connectivity among the nodes of wireless networks. Ensuring a reliable network operation under fading conditions is not straightforward, as the transmission schemes and the network topology, i.e., uniform or clustered deployments, affect the performance and should be taken into account. Moreover, as the number of nodes increases, exploiting natural energy sources and wireless energy harvesting (WEH) could be the key to the elimination of maintenance costs while also boosting immensely the network lifetime. In this way, zero-energy wireless-powered sensor networks (WPSNs) could be achieved, if all components are powered by green sources. Hence, designing accurate mathematical models that capture the network behavior under these circumstances is necessary to provide a deeper comprehension of such networks. In this paper, we provide an analytical model for the connectivity in a large-scale zero-energy clustered WPSN under two common transmission schemes, namely, unicast and broadcast. The sensors are WEH-enabled, while the network components are solar-powered and employ a novel energy allocation algorithm. In our results, we evaluate the tradeoffs among the various scenarios via extensive simulations and identify the conditions that yield a fully connected zero-energy WPSN.Peer ReviewedPostprint (author's final draft