7,497 research outputs found
On the Security of the Automatic Dependent Surveillance-Broadcast Protocol
Automatic dependent surveillance-broadcast (ADS-B) is the communications
protocol currently being rolled out as part of next generation air
transportation systems. As the heart of modern air traffic control, it will
play an essential role in the protection of two billion passengers per year,
besides being crucial to many other interest groups in aviation. The inherent
lack of security measures in the ADS-B protocol has long been a topic in both
the aviation circles and in the academic community. Due to recently published
proof-of-concept attacks, the topic is becoming ever more pressing, especially
with the deadline for mandatory implementation in most airspaces fast
approaching.
This survey first summarizes the attacks and problems that have been reported
in relation to ADS-B security. Thereafter, it surveys both the theoretical and
practical efforts which have been previously conducted concerning these issues,
including possible countermeasures. In addition, the survey seeks to go beyond
the current state of the art and gives a detailed assessment of security
measures which have been developed more generally for related wireless networks
such as sensor networks and vehicular ad hoc networks, including a taxonomy of
all considered approaches.Comment: Survey, 22 Pages, 21 Figure
Performance enhancement solutions in wireless communication networks
In this dissertation thesis, we study the new relaying protocols for different wireless network systems. We analyze and evaluate an efficiency of the transmission in terms of the outage probability over Rayleigh fading channels by mathematical analyses. The theoretical analyses are verified by performing Monte Carlo simulations.
First, we study the cooperative relaying in the Two-Way Decode-and-Forward (DF) and multi-relay DF scheme for a secondary system to obtain spectrum access along with a primary system. In particular, we proposed the Two-Way DF scheme with Energy Harvesting, and the Two-Way DF Non-orthogonal Multiple Access (NOMA) scheme with digital network coding. Besides, we also investigate the wireless systems with multi-relay; the best relay selection is presented to optimize the effect of the proposed scheme. The transmission protocols of the proposed schemes EHAF (Energy Harvesting Amplify and Forward) and EHDF (Energy Harvesting Decode and Forward) are compared together in the same environment and in term of outage probability. Hence, with the obtained results, we conclude that the proposed schemes improve the performance of the wireless cooperative relaying systems, particularly their throughput.
Second, we focus on investigating the NOMA technology and proposing the optimal solutions (protocols) to advance the data rate and to ensure the Quality of Service (QoS) for the users in the next generation of wireless communications. In this thesis, we propose a Two-Way DF NOMA scheme (called a TWNOMA protocol) in which an intermediate relay helps two source nodes to communicate with each other. Simulation and analysis results show that the proposed protocol TWNOMA is improving the data rate when comparing with a conventional Two-Way scheme using digital network coding (DNC) (called a TWDNC protocol), Two-Way scheme without using DNC (called a TWNDNC protocol) and Two-Way scheme in amplify-and-forward(AF) relay systems (called a TWANC protocol).
Finally, we considered the combination of the NOMA and physical layer security (PLS) in the Underlay Cooperative Cognitive Network (UCCN). The best relay selection strategy is investigated, which uses the NOMA and considers the PLS to enhance the transmission efficiency and secrecy of the new generation wireless networks.V tĂ©to dizertaÄnĂ prĂĄci je provedena studie novĂœch pĆenosovĂœch protokolĆŻ pro rĆŻznĂ© bezdrĂĄtovĂ© sĂĆ„ovĂ© systĂ©my. S vyuĆŸitĂm matematickĂ© analĂœzy jsme analyzovali a vyhodnotili efektivitu pĆenosu z hlediska pravdÄpodobnosti vĂœpadku pĆes RayleighĆŻv kanĂĄl. TeoretickĂ© analĂœzy jsou ovÄĆeny provedenĂœmi simulacemi metodou Monte Carlo.
Nejprve doĆĄlo ke studii kooperativnĂho pĆenosu ve dvoucestnĂ©m dekĂłduj-a-pĆedej (Two-Way Decode-and-ForwardâTWDF) a vĂcecestnĂ©m DF schĂ©matu s vÄtĆĄĂm poÄtem pĆenosovĂœch uzlĆŻ pro sekundĂĄrnĂ systĂ©m, kdy takto byl zĂskĂĄn pĆĂstup ke spektru spolu s primĂĄrnĂm systĂ©mem. KonkrĂ©tnÄ jsme navrhli dvoucestnĂ© DF schĂ©ma se zĂskĂĄvĂĄnĂm energie a dvoucestnĂ© DF neortogonĂĄlnĂ schĂ©ma s mnohonĂĄsobnĂœm pĆĂstupem (Non-orthogonal Multiple AccessâNOMA) s digitĂĄlnĂm sĂĆ„ovĂœm kĂłdovĂĄnĂm. KromÄ toho rovnÄĆŸ zkoumĂĄme bezdrĂĄtovĂ© systĂ©my s vÄtĆĄĂm poÄtem pĆenosovĂœch uzlĆŻ, kde je pĆĂtomen vĂœbÄr nejlepĆĄĂho pĆenosovĂ©ho uzlu pro optimalizaci efektivnosti navrĆŸenĂ©ho schĂ©matu. PĆenosovĂ© protokoly navrĆŸenĂœch schĂ©mat EHAF (Energy Harvesting Amplify and Forward) a EHDF(Energy Harvesting Decode and Forward) jsou spoleÄnÄ porovnĂĄny v identickĂ©m prostĆedĂ z pohledu pravdÄpodobnosti vĂœpadku. NĂĄslednÄ, na zĂĄkladÄ zĂskanĂœch vĂœsledkĆŻ, jsme dospÄli k zĂĄvÄru, ĆŸe navrĆŸenĂĄ schĂ©mata vylepĆĄujĂ vĂœkonnost bezdrĂĄtovĂœch kooperativnĂch systĂ©mĆŻ, konkrĂ©tnÄ jejich propustnost.
DĂĄle jsme se zamÄĆili na zkoumĂĄnĂ NOMA technologie a navrhli optimĂĄlnĂ ĆeĆĄenĂ (protokoly) pro urychlenĂ datovĂ©ho pĆenosu a zajiĆĄtÄnĂ QoS v dalĆĄĂ generaci bezdrĂĄtovĂœch komunikacĂ. V tĂ©to prĂĄci jsme navrhli dvoucestnĂ© DF NOMA schĂ©ma (nazĂœvĂĄno jako TWNOMA protokol), ve kterĂ©m mezilehlĂœ pĆenosovĂœ uzel napomĂĄhĂĄ dvÄma zdrojovĂœm uzlĆŻm komunikovat mezi sebou. VĂœsledky simulace a analĂœzy ukazujĂ, ĆŸe navrĆŸenĂœ protokol TWNOMA vylepĆĄuje dosaĆŸenou pĆenosovou rychlost v porovnĂĄnĂ s konvenÄnĂm dvoucestnĂœm schĂ©matem pouĆŸĂvajĂcĂm DNC (TWDNC protokol), dvoucestnĂœm schĂ©matem bez pouĆŸitĂ DNC (TWNDNC protokol) a dvoucestnĂœm schĂ©matem v zesil-a-pĆedej (amplify-and-forward) pĆenosovĂœch systĂ©mech (TWANC protokol).
Nakonec jsme zvĂĄĆŸili vyuĆŸitĂ kombinace NOMA a zabezpeÄenĂ fyzickĂ© vrstvy (Physical Layer SecurityâPLS) v podpĆŻrnĂ© kooperativnĂ kognitivnĂ sĂti (Underlay Cooperative Cognitive NetworkâUCCN). Zde je zde zkoumĂĄn vĂœbÄr nejlepĆĄĂho pĆenosovĂ©ho uzlu, kterĂœ uĆŸĂvĂĄ NOMA a bere v Ășvahu PLS pro efektivnÄjĆĄĂ pĆenos a zabezpeÄenĂ novĂ© generace bezdrĂĄtovĂœch sĂtĂ.440 - Katedra telekomunikaÄnĂ technikyvyhovÄ
Design and realization of precise indoor localization mechanism for Wi-Fi devices
Despite the abundant literature in the field, there is still the need to find a time-efficient, highly accurate, easy to deploy and robust localization algorithm for real use. The algorithm only involves minimal human intervention. We propose an enhanced Received Signal Strength Indicator (RSSI) based positioning algorithm for Wi-Fi capable devices, called the Dynamic Weighted Evolution for Location Tracking (DWELT). Due to the multiple phenomena affecting the propagation of radio signals, RSSI measurements show fluctuations that hinder the utilization of straightforward positioning mechanisms from widely known propagation loss models. Instead, DWELT uses data processing of raw RSSI values and applies a weighted posterior-probabilistic evolution for quick convergence of localization and tracking. In this paper, we present the first implementation of DWELT, intended for 1D location (applicable to tunnels or corridors), and the first step towards a more generic implementation. Simulations and experiments show an accuracy of 1m in more than 81% of the cases, and less than 2m in the 95%.Peer ReviewedPostprint (published version
Secure Communications in Millimeter Wave Ad Hoc Networks
Wireless networks with directional antennas, like millimeter wave (mmWave)
networks, have enhanced security. For a large-scale mmWave ad hoc network in
which eavesdroppers are randomly located, however, eavesdroppers can still
intercept the confidential messages, since they may reside in the signal beam.
This paper explores the potential of physical layer security in mmWave ad hoc
networks. Specifically, we characterize the impact of mmWave channel
characteristics, random blockages, and antenna gains on the secrecy
performance. For the special case of uniform linear array (ULA), a tractable
approach is proposed to evaluate the average achievable secrecy rate. We also
characterize the impact of artificial noise in such networks. Our results
reveal that in the low transmit powerregime, the use of low mmWave frequency
achieves better secrecy performance, and when increasing transmit power, a
transition from low mmWave frequency to high mmWave frequency is demanded for
obtaining a higher secrecy rate. More antennas at the transmitting nodes are
needed to decrease the antenna gain obtained by the eavesdroppers when using
ULA. Eavesdroppers can intercept more information by using a wide beam pattern.
Furthermore, the use of artificial noise may be ineffective for enhancing the
secrecy rate.Comment: Accepted by IEEE Transactions on Wireless Communication
Wireless industrial monitoring and control networks: the journey so far and the road ahead
While traditional wired communication technologies have played a crucial role in industrial monitoring and control networks over the past few decades, they are increasingly proving to be inadequate to meet the highly dynamic and stringent demands of todayâs industrial applications, primarily due to the very rigid nature of wired infrastructures. Wireless technology, however, through its increased pervasiveness, has the potential to revolutionize the industry, not only by mitigating the problems faced by wired solutions, but also by introducing a completely new class of applications. While present day wireless technologies made some preliminary inroads in the monitoring domain, they still have severe limitations especially when real-time, reliable distributed control operations are concerned. This article provides the reader with an overview of existing wireless technologies commonly used in the monitoring and control industry. It highlights the pros and cons of each technology and assesses the degree to which each technology is able to meet the stringent demands of industrial monitoring and control networks. Additionally, it summarizes mechanisms proposed by academia, especially serving critical applications by addressing the real-time and reliability requirements of industrial process automation. The article also describes certain key research problems from the physical layer communication for sensor networks and the wireless networking perspective that have yet to be addressed to allow the successful use of wireless technologies in industrial monitoring and control networks
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