Security Supports for Cyber-Physical System and its Communication Networks

A cyber-physical system (CPS) is a sensing and communication platform that features tight integration and combination of computation, networking, and physical processes. In such a system, embedded computers and networks monitor and control the physical processes through a feedback loop, in which physical processes affect computations and vice versa. In recent years, CPS has caught much attention in many different aspects of research, such as security and privacy. In this dissertation, we focus on supporting security in CPS and its communication networks. First, we investigate the electric power system, which is an important CPS in modern society. as crucial and valuable infrastructure, the electric power system inevitably becomes the target of malicious users and attackers. In our work, we point out that the electric power system is vulnerable to potential cyber attacks, and we introduce a new type of attack model, in which an attack cannot be completely identified, even though its presence may be detected. to defend against such an attack, we present an efficient heuristic algorithm to narrow down the attack region, and then enumerate all feasible attack scenarios. Furthermore, based on the feasible attack scenarios, we design an optimization strategy to minimize the damage caused by the attack. Next, we study cognitive radio networks, which are a typical communication network in CPS in the areas of security and privacy. as for the security of cognitive radio networks, we point out that a prominent existing algorithm in cooperative spectrum sensing works poorly under a certain attack model. In defense of this attack, we present a modified combinatorial optimization algorithm that utilizes the branch-and-bound method in a decision tree to identify all possible false data efficiently. In regard to privacy in cognitive radio networks, we consider incentive-based cognitive radio transactions, where the primary users sell time slices of their licensed spectrum to secondary users in the network. There are two concerns in such a transaction. The first is the primary user\u27s interest, and the second is the secondary user\u27s privacy. to verify that the payment made by a secondary user is trustworthy, the primary user needs detailed spectrum utilization information from the secondary user. However, disclosing this detailed information compromises the secondary user\u27s privacy. to solve this dilemma, we propose a privacy-preserving scheme by repeatedly using a commitment scheme and zero-knowledge proof scheme

Investigation of Security and Spectrum Management Issues in Cognitive Radio Aided by Machine Learning

University of Technology Sydney. Faculty of Engineering and Information Technology.Cognitive Radio (CR) is an intelligent and adaptive radio and network technology that allows transceivers to sense available frequency spectrum and change its parameters, to switch to available channels (frequency bands) without interruption to other connected transceivers. It is primarily a technology to resolve spectrum scarcity problems using Dynamic Spectrum Access (DSA). The potential aspects and applications of Cognitive radio are far superior to DSA alone. CR abilities and CR reconfiguration abilities are essential components for electronic warfare (communications). It provides capabilities for developing and deploying advanced anti-jamming methods, by assisting in the development of advanced intelligent, self-reconfiguration methods to alleviate the effects of jamming. This thesis examines the effects of jamming and other attacks on Cognitive Radio Networks and provides methods and processes to overcome those effects. Cognitive Radio architecture simulation was applied so that policies and their application correlate to Cognitive Radio jamming and anti-jamming issues. Simulation is employed for testing Multi-Armed Bandit and machine learning strategies/solutions as shown by this thesis. The central part of the thesis is the mitigation of jamming outcomes on Cognitive Radio Networks by using proactive steps to increase communication robustness and contentiousness. The thesis utilizes game theory (i.e. the Multi-Armed Bandit problem) and protection using Machine Learning (ProML) design for analysing jamming behavior on Cognitive Radio systems. MAB experiment show MAB approach is effective giants random attack, whereas, the proposed machine learning has its own merits to overcome constant and reactive jamming

Quickest Change Detection In Multiple On-off Processes: Switching With Memory

Abstract—We consider the quickest detection of idle periods in multiple on-off processes. At each time, only one process can be observed, and the observations are random realizations drawn from two different distributions depending on the current state (on or off) of the chosen process. Switching back to a previously visited process is allowed, and measurements obtained during previous visits are taken into account in decision making. The objective is to catch an idle period in any of the on-off processes as quickly as possible subject to a constraint on the probability of mistaking a busy period for an idle one. Assuming geometrically distributed busy and idle times, we establish a Bayesian formulation of the problem within a decisiontheoretic framework. Basic structures of the optimal decision rules are established. Based on these basic structures, we propose a low-complexity threshold policy for switching among processes and declaring idle periods. The near optimal performance of this threshold policy is demonstrated by a comparison with a genie-aided system which defines an upper bound on the optimal performance. This problem finds applications in spectrum opportunity detection in cognitive radio networks where a secondary user searches for idle channels in the spectrum. Index Terms—Quickest change detection, on-off process, spectrum opportunity detection, cognitive radio, genie-aided system I

Implementing opportunistic spectrum access in LTE-Advanced

Long term evolution advanced (LTE-A) has emerged as a promising mobile broadband access technology aiming to cope with the increasing traffic demand in wireless networks. However, the enhanced spectral efficiency offered by LTE-A may become futile without a better management of scarce and overcrowded electromagnetic spectrum. In this sense, cognitive radio (CR) has been proposed as a potential solution to the problem of spectrum scarcity. Among all the mechanisms provided by CR, opportunistic spectrum access (OSA) aims at a dynamic and seamless use of certain licensed bands provided the licensee is not harmfully affected. This operation requires spectral awareness in order to avoid interferences with licensed systems. In spite of implementing some spectrum sensing mechanisms, LTE-A technology lacks other tools that are needed in order to improve the knowledge of the radio environment. This work studies the adoption of a Geo-located data base (Geo-DB) that cooperatively retrieves and maintains information regarding the location of unutilized portions of spectrum potentially available for OSA. Moreover, the potential benefit of this LTE-compliant OSA solution is evaluated using a calibrated simulation tool, by which numerical results allow us to optimally configure the system and show that the proposed opportunistic system is able to significantly improve its performance.The authors would like to thank the funding received from the Ministerio de Ciencia e Innovacion within the Project number TEC2011-27723-C02-02 and from the Ministerio de Industria, Turismo y Comercio TSI-020100-2011-266 funds. This article had been written in the framework of the CELTIC project CP08-001 COMMUNE. Study by X. Gelabert is funded by the BP-DGR 2010 scholarship (ref. 00192). The authors would like to acknowledge the contributions of their colleagues.Osa Ginés, V.; Herranz Claveras, C.; Monserrat Del Río, JF.; Gelabert, X. (2012). Implementing opportunistic spectrum access in LTE-Advanced. EURASIP Journal on Wireless Communications and Networking. 2012(99):1-17. https://doi.org/10.1186/1687-1499-2012-99S117201299Martín-Sacristán D, Monserrat JF, Cabrejas-Peñuelas J, Calabuig D, Garrigas S, Cardona N: On the way towards fourth-generation mobile: 3GPP LTE and LTE-Advanced. EURASIP J Wirel Commun Netw 2009, 2009: 1-10.Ratasuk R, Tolli D, Ghosh A: Carrier aggregation in LTE-Advanced. In IEEE 71st Vehicular Technology Conference (VTC 2010-Spring). Taipei; 2010:1-5.Wang H, Rosa C, Pedersen K: Performance of uplink carrier aggregation in LTE-advanced systems. In IEEE 72nd Vehicular Technology Conference Fall (VTC 2010-Fall). Ottawa; 2010:1-5.Tandra R, Sahai A, Mishra S: What is a spectrum hole and what does it take to recognize one? Proc IEEE 2009, 97(5):824-848.Mitola IJ, Maguire JGQ: Cognitive radio: making software radios more personal. IEEE Personal Commun 1999, 6(4):13-18. 10.1109/98.788210Haykin S: Cognitive radio: brain-empowered wireless communications. IEEE J Sel Areas Commun 2005, 23(2):201-220.IEEE 802.22 Working Group on Wireless Regional Area Networks. [ http://www.ieee802.org/22/ ]ITU-R BT1368: Planning criteria for digital terrestrial television services in the VHF/UHF bands.ITU-R BT1786: Criterion to assess the impact of interference to the terrestrial broadcasting service (BS).Kawade S, Nekovee M: Cognitive radio-based urban wireless broadband in unused TV bands. In 20th International Radioelektronika Conference. Brno; 2010:1-4.Modlic B, Sisul G, Cvitkovic M: Digital dividend--Opportunities for new mobile services. In International Symposium ELMAR 2009 (ELMAR'09). Zadar; 2009:1-8.Zhao X, Guo Z, Guo Q: A cognitive based spectrum sharing scheme for LTE advanced systems. In International Congress on Ultra Modern Telecommunications and Control Systems and Workshops (ICUMT). Moscow; 2010:965-969.Hussain S, Fernando X: Spectrum sensing in cognitive radio networks: Up-to-date techniques and future challenges. In IEEE Toronto International Conference on Science and Technology for Humanity (TIC-STH). Toronto; 2009:736-741.Xu Y, Sun Y, Li Y, Zhao Y, Zou H: Joint sensing period and transmission time optimization for energy-constrained cognitive radios. EURASIP J Wirel Commun Netw 2010, 2010: 1-16.Yucek T, Arslan H: A survey of spectrum sensing algorithms for cognitive radio applications. IEEE Commun Surv Tutor 2009, 11: 116-130.Cabric D, Mishra S, Brodersen R: Implementation issues in spectrum sensing for cognitive radios. In Conference Record of the Thirty-Eighth Asilomar Conference on Signals, Systems and Computers. Volume 1. Pacific Grove; 2004:772-776.Zeng Y, Liang YC, Hoang A, Peh E: Reliability of spectrum sensing under noise and interference uncertainty. In IEEE International Conference on Communications Workshops, 2009. ICC Workshops. Dresden; 2009:1-5.Bixio L, Ottonello M, Raffetto M, Regazzoni CS: Comparison among cognitive radio architectures for spectrum sensing. EURASIP J Wirel Commun Netw 2011, 2011: 1-18.Mustonen M, Matinmikko M, Mammela A: Cooperative spectrum sensing using quantized soft decision combining. In 4th International Conference on Cognitive Radio Oriented Wireless Networks and Communications, 2009 (CROWNCOM'09). Hannover; 2009:1-5.Xiao L, Liu K, Ma L: A weighted cooperative spectrum sensing in cognitive radio networks. In International Conference on Information Networking and Automation (ICINA). Volume 2. Kunming; 2010:45-48.Pan Q, Chang Y, Zheng R, Zhang X, Wang Y, Yang D: Solution of information exchange for cooperative sensing in cognitive radios. In IEEE Wireless Communications and Networking Conference, 2009 (WCNC'2009). Budapest; 2009:1-4.Masri A, Chiasserini CF, Perotti A: Control information exchange through UWB in cognitive radio networks. In 5th IEEE International Symposium on Wireless Pervasive Computing (ISWPC). Modena; 2010:110-115.Celebi H, Arslan H: Utilization of location information in cognitive wireless networks. IEEE Wirel Commun 2007, 14(4):6-13.FCC: Notice of Proposed Rulemaking, in the Matter of Unlicensed Operation in the TV Broadcast Bands (ET Docket no. 04-186) and Additional Spectrum for Unlicensed.Marcus MJ, Kolodzy P, Lippman A: Reclaiming the vast wasteland: why unlicensed use of the white space in the TV bands will not cause interference to DTV viewers. New America Foundation: wireless future program, tech rep 2005.Nam H, Ghorbel M, Alouini M: Proc. of the Fifth International Conference on Cognitive Radio Oriented. In Proc of the Fifth International Conference on Cognitive Radio Oriented Wireless Networks Communications (CROWNCOM). Cannes; 2010:1-5.IEEE Std 80221-2008: IEEE Standard for Local and Metropolitan Area Networks-Part 21: Media Independent Handover. 2009.3GPP TS 36133: Evolved Universal Terrestrial Radio Access (E-UTRA); Requirements for support of radio resource management.Sesia S, Baker M, Toufik I: LTE, the UMTS long term evolution: from theory to practice. Wiley, New Haven; 2009.Digham FF, Alouini MS, Simon MK: On the energy detection of unknown signals over fading channels. In IEEE International Conference on Communications, 2003 (ICC'03). Volume 5. Anchorage; 2003:3575-3579.Ghasemi A, Sousa ES: Collaborative spectrum sensing for opportunistic access in fading environments. In First IEEE International Symposium on New Frontiers in Dynamic Spectrum Access Networks (DySPAN). Baltimore; 2005:131-136.Gelabert X, Akyildiz IF, Sallent O, Agustí R: Operating point selection for primary and secondary users in cognitive radio networks. Comput Netw 2009, 53(8):1158-1170. 10.1016/j.comnet.2009.02.009Taniuchi K, Ohba Y, Fajardo V, Das S, Tauil M, Cheng YH, Dutta A, Baker D, Yajnik M, Famolari D: IEEE 802.21: media independent handover: features, applicability, and realization. IEEE Commun Mag 2009, 47: 112-120.3GPP TS 36305: Evolved Universal Terrestrial Radio Access Network (E-UTRAN); Stage 2 functional specification of User Equipment (UE) positioning in E-UTRAN.3GPP TS 36355: Evolved Universal Terrestrial Radio Access; LTE Positioning Protocol (LPP).3GPP TS 36455: Evolved Universal Terrestrial Radio Access; LTE Positioning Protocol A (LPPa).Ren W, Zhao Q, Swami A: Power control in cognitive radio networks: how to cross a multi-lane highway. IEEE J Sel Areas Commun 2008, 27(7):1283-1296.3GPP R1-084424: Control Channel Design Issues for Carrier Aggregation in LTE-A.Dajie J, Haiming W, Malkamaki E, Tuomaala E: Principle and performance of semi-persistent scheduling for VoIP in LTE system. In International Conference on Wireless Communications, Networking and Mobile Computing, 2007 (WiCom 2007). Shanghai; 2007:2861-2864.Rajbanshi R, Wyglinski AM, Minden GJ: An efficient implementation of NC-OFDM transceivers for cognitive radios. In Proc of 1st Conf on Cognitive Radio Oriented Wireless Networks and Commun. Mykonos; 2006:1-5.Wellens M, Riihijarvi J, Mahonen P: Modeling primary system activity in dynamic spectrum access networks by aggregated ON/OFF-processes. In 6th Annual IEEE Communications Society Conference on Sensor, Mesh and Ad Hoc Communications and Networks Workshops, 2009. SECON Workshops'09. Rome; 2009:1-6.3GPP TS 36214: Physical layer; Measurements.Ofuji Y, Morimoto A, Abeta S, Sawahashi M: Comparison of packet scheduling algorithms focusing on user throughput in high speed downlink packet access. In 13th IEEE International Symposium on Personal, Indoor and Mobile Radio Communications. Volume 3. Lis-boa; 2002:1462-1466.ITU-R ITU M2135: Guidelines for evaluation of radio interface technologies for IMT-Advanced 2008

Αναδιάρθρωση Αναθέσεων Πόρων σε Δίκτυα Γνωσιακής Ραδιοεπικοινωνίας

241 σ.Το στατικό μοντέλο διαχείρισης του ραδιοφάσματος αδυνατεί να ικανοποιήσει τη συνεχώς αυξανόμενη ζήτηση πρόσβασης στον εν λόγω πόρο, αποτελώντας ουσιαστικά τροχοπέδη στην ανάπτυξη περαιτέρω καινοτόμων ασύρματων υπηρεσιών. Ως καταλληλότερη τεχνολογία για την αποκατάσταση της αποδοτικότητας στον τρόπο εκμετάλλευσης του ραδιοφάσματος θεωρείται σήμερα η Γνωσιακή Ραδιοεπικοινωνία. Η εν λόγω τεχνολογία παρέχει στις ασύρματες συσκευές την ευελιξία να εκμεταλλεύονται ευκαιριακά μη-χρησιμοποιούμενες μερίδες του ραδιοφάσματος, προδιαγράφοντας τρείς θεμελιώδεις διαδικασίες, ήτοι την "Παρακολούθηση Φάσματος", τον "Μερισμό Φάσματος" και την "Κινητικότητα Φάσματος". Η παρούσα διδακτορική διατριβή εντάσσεται στο ευρύτερο ερευνητικό πεδίο της Γνωσιακής Ραδιοεπικοινωνίας και πραγματεύεται ανοιχτά θέματα τα οποία άπτονται και των τριών ανωτέρω διαδικασιών. Συγκεκριμένα, στην παρούσα διατριβή προσεγγίζεται το δημοφιλές πρόβλημα της Συνδυασμένης Εκχώρησης Καναλιών και Δρομολόγησης (διαδικασία "Μερισμού Φάσματος") υπό το πρίσμα των Δικτύων Γνωσιακής Ραδιοεπικοινωνίας και, βάσει αυτού, προτείνεται ένας μηχανισμός ελαχιστοποίησης της επιβάρυνσης η οποία προκαλείται στα εν λόγω δίκτυα κατά τη συχνότερη αναδιάρθρωση των αναθέσεων πόρων τους (διαδικασία "Κινητικότητας Φάσματος"). Τόσο το ανωτέρω πρόβλημα μερισμού φάσματος, όσο και ο μηχανισμός αποδοτικής αναδιάρθρωσης αναθέσεων πόρων μοντελοποιούνται, αρχικά, ως προβλήματα βελτιστοποίησης, ενώ στη συνέχεια αναζητούνται κατάλληλες ευρετικές μέθοδοι με σκοπό την πλησιοβέλτιστη επίλυση των εν λόγω προβλημάτων και, κατ’ επέκταση, την αποκατάσταση της δυνατότητας εφαρμογής τους σε πρακτικά Δίκτυα Γνωσιακής Ραδιοεπικοινωνίας. Ειδικότερα, για τον προδιαγραφόμενο μηχανισμό βέλτιστης αναδιάρθρωσης αναθέσεων πόρων, προτείνεται μια εξαιρετικά αποδοτική, εξειδικευμένη στο συγκεκριμένο πρόβλημα ευρετική μέθοδος. Στα πλαίσια της παρούσας διατριβής πραγματοποιείται, επίσης, μια Επισκόπηση Κατάληψης Φάσματος στη μητροπολιτική περιοχή των Αθηνών, ώστε να αξιολογηθεί η δυνατότητα του πραγματικού περιβάλλοντος ραδιοσυχνοτήτων να υποστηρίξει την εφαρμογή της τεχνολογίας της Γνωσιακής Ραδιοεπικοινωνίας στην πράξη και, κατ’ επέκταση, να ενδυναμωθεί η πρακτικότητα της πραγματοποιούμενης έρευνας. Κατόπιν ενδελεχούς εξέτασης των συλλεγμένων δεδομένων μετρήσεων, τέλος, αναδεικνύεται η ύπαρξη συσχετίσεων στη μετρούμενη ενέργεια γειτονικών καναλιών και, εν συνεχεία, προτείνεται μια μεθοδολογία η οποία εκμεταλλεύεται την εν λόγω ιδιότητα, επιτρέποντας στις ασύρματες συσκευές να αυξάνουν την ενημερότητά τους επί του εξ ορισμού άγνωστου περιβάλλοντος ραδιοσυχνοτήτων τους επεξεργαζόμενες αποκλειστικά όσα δεδομένα συλλέγουν κατά την τυπικά εφαρμοζόμενη διαδικασία της "Παρακολούθησης Φάσματος". Η αποκτώμενη ενημερότητα, μάλιστα, δύναται να δράσει υποστηρικτικά επί του συνόλου των διαδικασιών τις οποίες ορίζει η τεχνολογία της Γνωσιακής Ραδιοεπικοινωνίας και – σε συνδυασμό με τον προτεινόμενο μηχανισμό βέλτιστης αναδιάρθρωσης αναθέσεων πόρων – να βελτιώσει σημαντικά την αποδοτικότητα των αντίστοιχων δικτύων.The current statically established model of spectrum management is unable to satisfy the constantly growing demand of users and networks for spectrum access, essentially obstructing the deployment of new and innovative wireless services in practice. Cognitive Radio is considered a promising technology for restoring efficiency in spectrum utilization, by providing the wireless devices with the flexibility to opportunistically exploit unused spectrum portions that potentially exist in their wireless environment. Cognitive Radio technology specifies in practice three fundamental processes, namely the "Spectrum Monitoring", the "Spectrum Sharing" and the "Spectrum Mobility", and this thesis focuses on the study of open issues related to all these three layers of conception. More specifically, the popular problem of Joint Channel Assignment and Routing ("Spectrum Sharing" process) is considered from the perspective of Cognitive Radio Networks and, based on that, a novel mechanism is proposed with the ulterior view to minimize the overhead that is induced on such networks during their frequent resource allocation reconfigurations ("Spectrum Mobility" process). Both the Joint Channel Assignment and Routing problem, as well as the proposed reconfiguration mechanism are first modeled as optimization problems. Then, proper heuristic methods are investigated for quickly providing near-optimal solutions to the above problems and, thus, making it viable to be applied to realistic Cognitive Radio Networks scaling in commercial sizes. Especially for the proposed reconfiguration mechanism, a novel and efficient heuristic method is designed, which exploits the unique nature of the respective optimization problem. Furthermore, within the framework of this dissertation, a Spectrum Occupancy Survey is carried out in the metropolitan area of Athens, aiming at evaluating the ability of the real spectrum environment to support the application of the Cognitive Radio technology in practice and, thus, empower the practicality of the conducted research. Finally, by further processing the collected measurement data, the existence of correlation properties in the sensed power of measured neighboring channels is advocated and, based on them, a new methodology is proposed for enabling the wireless devices to raise their awareness on their otherwise unknown operating spectrum environment by simply leveraging data that are collected during the typically applied "Spectrum Monitoring" process. Notably, the acquired awareness can be well exploited for improving all the above processes defined by the Cognitive Radio technology and – in combination with the proposed reconfiguration mechanism – to further increase the efficiency of such networks.Σταμάτιος Γ. Αρκουλή