691 research outputs found
A novel multi-fold security framework for cognitive radio wireless ad-hoc networks
Cognitive Radio (CR) Technology has emerged as a smart and intelligent technology to address the problem of spectrum scarcity and its under-utilization. CR nodes sense the environment for vacant channels, exchange control information, and agree upon free channels list (FCL) to use for data transmission and conclusion. CR technology is heavily dependent on the control channel to dialogue on the exchanged control information which is usually in the Industrial-Scientific-Medical (ISM) band. As the ISM band is publically available this makes the CR network more prone to security vulnerabilities and flaws. In this paper a novel multi-fold security framework for cognitive radio wireless ad-hoc networks has been proposed. Multiple security levels, such as, encryption of beacon frame and privately exchanging the FCL, and the dynamic and adaptive behaviour of the framework makes the proposed protocol more resilient and secure against the traditional security attacks when compared with existing protocols
Cognitive radio-enabled Internet of Vehicles (IoVs): a cooperative spectrum sensing and allocation for vehicular communication
Internet of Things (IoTs) era is expected to empower all aspects of Intelligent Transportation System (ITS) to improve transport safety and reduce road accidents. US Federal Communication Commission (FCC) officially allocated 75MHz spectrum in the 5.9GHz band to support vehicular communication which many studies have found insufficient. In this paper, we studied the application of Cognitive Radio (CR) technology to IoVs in order to increase the spectrum resource opportunities available for vehicular communication, especially when the officially allocated 75MHz spectrum in 5.9GHz band is not enough due to high demands as a result of increasing number of connected vehicles as already foreseen in the near era of IoTs. We proposed a novel CR Assisted Vehicular NETwork (CRAVNET) framework which empowers CR enabled vehicles to make opportunistic usage of licensed spectrum bands on the highways. We also developed a novel co-operative three-state spectrum sensing and allocation model which makes CR vehicular secondary units (SUs) aware of additional spectrum resources opportunities on their current and future positions and applies optimal sensing node allocation algorithm to guarantee timely acquisition of the available channels within a limited sensing time. The results of the theoretical analyses and simulation experiments have demonstrated that the proposed model can significantly improve the performance of a cooperative spectrum sensing and provide vehicles with additional spectrum opportunities without harmful interference against the Primary Users (PUs) activities
Timely and reliable packets delivery over Internet of Vehicles (IoVs) for road accidents prevention: a cross-layer approach
With the envisioned era of Internet of Things (IoTs), all aspects of Intelligent Transportation Systems (ITS) will be connected to improve transport safety, relieve traffic congestion, reduce air pollution, enhance the comfort of transportation and significantly reduce road accidents. In IoVs, regular exchange of current position, direction, velocity, etc., enables mobile vehicles to predict an upcoming accident and alert the human drivers in time or proactively take precautionary actions to avoid the accident. The actualization of this concept requires the use of channel access protocols that can guarantee reliable and timely broadcast of safety messages. This paper investigates the application of network coding concept to increase content of every transmission and achieve improved broadcast reliability with less number of retransmission. In particular, we proposed Code Aided Retransmission-based Error Recovery (CARER) scheme, introduced an RTB/CTB handshake to overcome hidden node problem and reduce packets collision rate. In order to avoid broadcast storm problem associated with the use of RTB/CTB packet in a broadcast transmission, we developed a rebroadcasting metric used to successfully select a vehicle to rebroadcast the encoded message. The performance of CARER protocol is clearly shown with detailed theoretical analysis and further validated with simulation experiments
Corporate Lobbying and ESG Reports: Patterns among US Companies, 1999–2017
To lobby legislators, it is important for interest groups to signal their ability to help legislators win elections and provide them with policy-relevant information. We explore for-profit companies’ use of environmental, social, and governance (ESG) reports as a signaling device to promote their reputation to legislators and convey their ability to provide electoral and policymaking support, which is valuable for lobbying. To this end, we create a panel dataset by combining ESG reports issued by US companies and the same companies’ lobbying and campaign contribution records from 1999 to 2017. We expect companies to issue more ESG reports, as well as reports containing more quantitative content, when they lobby. The data conform to our expectations. We also reason that lobbying may be more strongly related to ESG reporting when it is coupled with campaign contributions made by affiliated corporate political action committees, but the data do not support this expectation
Discontinuous Galerkin Methods for an Elliptic Optimal Control Problem with a General State Equation and Pointwise State Constraints
We investigate discontinuous Galerkin methods for an elliptic optimal control
problem with a general state equation and pointwise state constraints on
general polygonal domains. We show that discontinuous Galerkin methods for
general second-order elliptic boundary value problems can be used to solve the
elliptic optimal control problems with pointwise state constraints. We
establish concrete error estimates and numerical experiments are shown to
support the theoretical results
Battery-assisted Electric Vehicle Charging: Data Driven Performance Analysis
As the number of electric vehicles rapidly increases, their peak demand on
the grid becomes one of the major challenges. A battery-assisted charging
concept has emerged recently, which allows to accumulate energy during off-peak
hours and in-between charging sessions to boost-charge the vehicle at a higher
rate than available from the grid. While prior research focused on the design
and implementation aspects of battery-assisted charging, its impact at large
geographical scales remains largely unexplored. In this paper we analyse to
which extent the battery-assisted charging can replace high-speed chargers
using a dataset of over 3 million EV charging sessions in both domestic and
public setting in the UK. We first develop a discrete-event EV charge model
that takes into account battery capacity, grid supply capacity and power output
among other parameters. We then run simulations to evaluate the
battery-assisted charging performance in terms of delivered energy, charging
time and parity with conventional high-speed chargers. The results indicate
that in domestic settings battery-assisted charging provides 98% performance
parity of high-speed chargers from a standard 3 kW grid connection with a
single battery pack. For non-domestic settings, the battery-assisted chargers
can provide 92% and 99% performance parity of high-speed chargers with 10
battery packs using 3kW and 7kW grid supply respectively.Comment: Paper presented at 2020 IEEE PES ISGT Conference (26-28 October 2020
- …