"In a wireless network environment, all the users are able to access the wireless channel. Thus, if malicious users exploit this feature by mimicking the characteristics of a normal user or even the central wireless access point (AP), they can intercept almost all the information through the network. This scenario is referred as a Man-in-the-middle (MITM) attack. In the MITM attack, the attackers usually set up a rogue AP to spoof the clients. In this thesis, we focus on the detection of MITM attacks in Wi-Fi networks. The thesis introduces the entire process of performing and detecting the MITM attack in two separate sections. The first section starts from creating a rogue AP by imitating the characteristics of the legitimate AP. Then a multi-point jamming attack is conducted to kidnap the clients and force them to connect to the rogue AP. Furthermore, the sniffer software is used to intercept the private information passing through the rogue AP. The second section focuses on the detection of MITM attacks from two aspects: jamming attacks detection and rogue AP detection. In order to enable the network to perform defensive strategies more effectively, distinguishing different types of jamming attacks is necessary. We begin by using signal strength consistency mechanism in order to detect jamming attacks. Then, based on the statistical data of packets send ratio (PSR) and packets delivery ratio (PDR) in different jamming situations, a model is built to further differentiate the jamming attacks. At the same time, we gather the received signal strength indication (RSSI) values from three monitor nodes which process the random RSSI values employing a sliding window algorithm. According to the mean and standard deviation curve of RSSI, we can detect if a rogue AP is present within the vicinity. All these proposed approaches, either attack or detection, have been validated via computer simulations and experimental hardware implementations including Backtrack 5 Tools and MATLAB software suite. "

Malfunction is a science fiction thriller that explores what the other extreme of mental health awareness could look like. A system that is TOO technologically equipped, proactive and sure in its ability to solve every mental health illness. but can such a perfect world ever exist? not everyone in this world has good intentions and if you try to go against the norm...you may not survive.

<!--st1\:*{behavior:url(#ieooui) } -->&lt;!--[endif]--&gt; <!-- /* Font Definitions */ @font-face {font-family:Garamond; panose-1:2 2 4 4 3 3 1 1 8 3; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:647 0 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; punctuation-wrap:simple; text-autospace:none; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 70.85pt 70.85pt 70.85pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --> To implement a utility wireless sensor network, investigation of different wireless protocols has been performed. The protocols are Bluetooth, Wi-Fi, IEEE 802.15.4 and Zigbee. Consecutively literature studies have made it comprehensible to understand the function of the protocols that are suitable for development of wireless sensor networks. The importance of low cost, low power, reliable and high-quality properties for long distances are significant. IEEE 802.15.4 and Zigbee protocol are proper to implement as a wireless sensor network.   To reduce the human efforts in the configuration of the system, a comfortable method is implemented to facilitate the procedure. The applied method is based on an automatic configuration of the system. The configuration and the decision taking are implemented in the software. The system is designed to avoid interference to other wireless networks with the possibilities of reconfiguration. A uniform hardware and software design with separate functions of the system decided by a subsequent command for configuration is preferable. This imposes an advantage that increases the flexible potential of the system when a uniform solution is implemented.   To support the basic communication principles and control of the system, a buffer implementation has been introduced. The functionality of decision taking is distributed, configured by system commands from the host system. Detecting of system commands requires a properly operating buffer management. In consideration to the power consumption in reference to battery utilizations, the settings of RF-module and microcontroller have a powerful impact to reduce the power consumption. All possibilities of hibernates and avoidance of unnecessarily transmitting, should be deactivated to minimize the power consumption.

Nous avons assisté ces dernières années à la montée en puissance des réseaux locaux sans fil ou encore Wi-Fi, qui sont en passe de devenir l'une des principales solutions de connexion pour de nombreuses entreprises. Le marché du sans fil se développe rapidement dès lors que les entreprises constatent les gains de productivité qui découlent de la disparition des câbles. Avec cette évolution rapide de ce type dématérialisé de réseaux, les exigences en termes de sécurité deviennent de plus en plus sévères. De ce fait, beaucoup de travaux et d'efforts ont été consentis ces dernières années afin d'aboutir à des solutions pour sécuriser ces réseaux. Toutefois, des vulnérabilités persistent encore et il est toujours possible de monter des attaques plus ou moins facilement. Notamment, contre le dernier né des protocoles de sécurité Wi-Fi, à savoir WPA2, qui bien qu'étant plus robuste sur le plan conceptuel que les générations précédentes, fait face à un problème majeur, celui de son incompatibilité matérielle avec les précédents protocoles. En effet, WPA2 exige de nouveaux équipements matériels, ce qui constitue un surcoût économique énorme pour les entreprises ayant déjà déployé des équipements Wi-Fi d'anciennes générations. Dans ce mémoire, nous élaborons une synthèse exhaustive de toutes les attaques qui ciblent les réseaux Wi-Fi. Cette synthèse comprend une classification des attaques par rapport aux standards de sécurité ainsi que l'illustration des détails de leur mise en œuvre. Outre le volet conceptuel et théorique, nous abordons également le volet pratique et montrons sa richesse. Nous proposons également une nouvelle approche architecturale de sécurisation des réseaux Wi-Fi dans l'entreprise. Notre proposition prend en compte l'hétérogénéité des équipements et des standards de sécurité supportés. Cette nouvelle architecture a le mérite d'offrir une grande flexibilité ainsi qu'une sécurité renforcée par rapport aux approches traditionnelles. Pour élaborer cette solution sécurisée, nous nous sommes basés principalement sur la différenciation à plusieurs niveaux (standard de sécurité supporté, communauté d'utilisateurs, nature de trafic). Ces niveaux de différenciation offrent la granularité nécessaire pour permettre une meilleure gestion du réseau et un meilleur contrôle d'accès aux ressources, ce qui améliore la sécurité du réseau Wi-Fi en particulier et du système d'information de l'entreprise dans son ensemble. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : Wi-Fi, sécurité, attaque, architecture sécurisée, différenciation.

Les xarxes d'àrea local sense fils (WLANs), principalment les basades en les diverses versions de les normes IEEE 802.11, i més concretament, aquelles operant en mode infraestructura (ús de punts d'accés o APs), són avui dia les tecnologies més populars per a l'accés ràdio de banda ampla a xarxes IP, ja sigui per a estendre petites xarxes LAN domèstiques (SOHO), o per a proporcionar accés d'Internet en espais públics. A més, amb l'arribada de productes amb el certificat Wi-Fi, els diferents fabricants de dispositius WLAN proporcionen un alt nivell d'interoperabilitat.No obstant això, la creixent densitat de punts d'accés WLAN ha començat a revelar els efectes negatius i les deficiències de les normes IEEE 802.11 inicials. Un dels factors clau del seu èxit, l'ús de la bandes de freqüència lliures (bandes ISM), és al mateix temps un dels seus grans inconvenients. Aquestes freqüències són de lliure accés al públic en general, i es defineixen dins d'una petita porció de l'espectre. En conseqüència, són generalment compartides entre diversos usuaris, dispositius de tecnologies diferents, etc.. A més, el control d'accés al medi definit per l'IEEE 802.11 (CSMA, o "escoltar abans de parlar") requereix una atenció especial a tots els problemes sorgits al voltant de les interferències.En aquest escenari, les xarxes WLAN IEEE no estan en condicions d'arribar a explotar tot el seu potencial. Malgrat aquest fet, unes polítiques intel·ligents sobre la gestió dels recursos ràdio (RRM) poden ajudar a reduir al mínim els efectes perjudicials de les interferències i d'una distribució desigual de la càrrega oferta. En aquesta tesi, es demostra que els mecanismes de RRM eficients són capaços de millorar notablement el rendiment d'una WLAN basada en l'IEEE 802.11.Aquesta tesi estudia la forma d'entendre els problemes de rendiment que són endèmics en les WLANs IEEE 802.11, així com les formes de minimitzar aquests efectes negatius per mitjà de la gestió de recursos ràdio. De fet, aquests problemes no són nous i han estat àmpliament estudiats des de l'aparició de xarxes de comunicacions mòbils, però les característiques particulars de les xarxes WLAN 802,11 requereixen nous enfocaments.Els mecanismes RRM en l'àmbit de les xarxes WLAN IEEE 802.11 són bàsicament destinats a reduir el grau de contenció i la interferència. Aquesta reducció es tradueix en una millor qualitat d'experiència (QoE), d'acord amb la percepció dels usuaris. Amb aquesta finalitat, RRM ha de proporcionar mecanismes eficients d'assignació de canals, algoritmes de selecció de modulació, control de potència i repartiment de càrrega. Atesa la naturalesa dinàmica de la propagació ràdio, i a causa de la mobilitat dels usuaris, els paràmetres que defineixen l'entorn sense fils varien amb el temps. Llavors, per tal de mantenir el rendiment en nivells acceptables, s'han de trobar mecanismes RRM que permetin una reconfiguració automàtica i dinàmica de la xarxa en resposta als canvis en el medi. En resum, podem construir el nostre escenari d'interès a partir de dispositius Wi-Fi intel·ligents capaços de cooperar, ja sigui de forma centralitzada o distribuïda, per tal de fer un millor ús dels minsos recursos ràdio.La nostra contribució als mecanismes RRM en xarxes WLAN s'inicia amb l'estudi i la caracterització de la interferència en l'àmbit particular de les xarxes IEEE 802.11. A continuació, desenvolupem un model de capacitat per a grans xarxes WLAN multi cel·la que té en compte tant l'efecte de la càrrega de la xarxa, com el de les interferències entre cel·les. El model també inclou l'efecte de l'adaptació automàtica de modulació que porten a terme molts dispositius. Aquestes estimacions de la capacitat són útils per a avaluar els beneficis d'un mecanisme RRM. Per exemple, aquestes estimacions són la base sobre la qual desenvolupem una innovadora solució per a la gestió de freqüències. Aquest mecanisme d'assignació de freqüències fa ús de tot l'espectre disponible (tant si es tracta de canals ISM solapats o no), ja que té en compte els efectes dels dos tipus d'interferència que trobem en xarxes IEEE 802.11: co-canal i per canal adjacent. Per tal de fer front a una distribució desigual de la càrrega, fet que es dóna típicament en els anomenats hotspots, es proposen dos mecanismes de repartiment de càrrega (un cop definit el concepte de càrrega): un enfocament distribuït gestionat per les estacions client, i un mecanisme de "cell breathing".Tots aquests mecanismes han de ser integrats en una arquitectura de gestió aglutinadora. En aquest sentit, s'han desenvolupat dues arquitectures de RRM: una arquitectura centralitzada, com a part del projecte UAMN, i un sistema distribuït. / WLANs, primarily the various versions of IEEE 802.11 standards, and more precisely, those operating in infrastructure mode, are nowadays the most popular technologies for providing broadband radio access to IP networks, whether to extend Small Office/Home Office (SOHO) network LANs or to provide Internet access in public places. Moreover, with the advent of Wi-Fi certified products, different competitive brands of WLAN devices are interoperable at a basic level of service.However, the increasing density of WLAN access points has started to reveal the negative effects and shortcomings of the original IEEE 802.11 standards. One of its key success factors, the use of unlicensed Industrial Scientific Medical (ISM) frequency bands, is at the same time one of its major drawbacks. These frequencies are freely available to the general public. On the other hand, such frequencies are defined within a small portion of the spectrum and are usually shared among several users. Besides, the medium access defined by the IEEE 802.11 (CSMA, or "listen before talk") requires a special attention to all interference issues.In this scenario, IEEE WLANs are unable to exploit all their potential. However, intelligent radio resource management (RRM) policies could be applied to minimize the harmful effects of interference and an uneven load distribution. Throughout this dissertation, it is shown that efficient RRM mechanisms are able to improve notably the performance of a legacy IEEE WLAN.This thesis explores ways of understanding the performance issues that are endemic to IEEE 802.11 WLANs, as well as ways of minimizing these negative effects by means of radio resource management. In fact, these problems are not new and have been studied extensively since the advent of mobile communications networks, but the particular characteristics of the 802.11 WLANs require new approaches.RRM mechanisms in the field of IEEE 802.11 WLANs are basically intended to reduce contention and interference. This reduction is translated into an improved Quality of Experience (QoE), as perceived by the users. To this end, RRM should provide efficient channel allocation mechanisms, modulation selection algorithms, power control and load balancing. Given the dynamic nature of radio propagation, and due to user mobility, the parameters that define the wireless environment vary in time. Therefore, in order to maintain the required performance, we should find mechanisms that allow a dynamic and automatic reconfiguration of the network in response to the changes in the environment. To sum up, we build our scenario of interest with intelligent Wi-Fi devices capable of cooperating either in a centralized or a distributed manner, in order to make a better use of the shared and scarce radio resources.Our contribution to RRM on WLANs starts with the study and characterization of interference in the particular field of IEEE 802.11 networks. Following, we develop a capacity model for large WLAN deployments that takes both the effect of carried traffic and inter-cell interference into account. The model also includes the effect of rate adaptation. These capacity estimations are useful to evaluate the benefits of a RRM mechanism, for example, it was used as the metric observed by a frequency management approach. This frequency assignment mechanism makes use of all the available spectrum (overlapping and non-overlapping ISM channels), since it takes the effects of both co-channel and adjacent-channel interference into account. In order to cope with the uneven load distribution usually found on hot-spots, two load balancing mechanisms are proposed after defining the concept of load: a client-driven approach, and a cell-breathing mechanism. All these mechanisms need to be integrated into a single architecture. In this regard, two radio resource management architectures are developed: a centralized architecture, as part of the UAMN project, and a distributed scheme.

Wireless sensor network, which is constitute of autonomous sensors, is used for monitoring physical or environmental conditions like temperature, sound, pressure, and so on. The dispersed sensors or nodes will respectively pass their data through the network to the main location. Currently, several standards are ratified or in developing for wireless sensor network, like Wireless Hart, ISA, 100.11a, WIA-PAA, IEEE 802.15.4, etc. Among the standards, Zigbee is often used in industrial applications that require short-range and low-rate wireless transfer. In the research, all the data is collected under industrial environment using IEEE 802.15.4 compliant physical layer, some packets are interfered only by multi-path fading while others are also interfered by Wi-Fi interference. The goal of the thesis is to find out the dependence between the received power (RSS), correlation value (CORR) and bit error rate (BER) of the received message, and their distribution in situations both when the packet is lost or not. Besides, the performance of bit error rate such as the distribution and the features of burst error length under Wi-Fi interference or not will also be tested. All of them are based on a precise statistical processing.

<p>In our homes and in the enterprise, in our leisure and in our professions, mobile computing is no longer merely "exciting;" it is becoming an essential, ubiquitous tool of the modern world. New and innovative mobile applications continue to inform, entertain, and surprise users. But, to make the daily use of mobile technologies more gratifying and worthwhile, we must move forward with new levels of sophistication. The Mobile App Stores of the future must be built on stronger foundations. </p><p>This dissertation considers a broad view of the challenges and intuitions behind a diverse selection of such new primitives. Some of these primitives will mitigate existing and fundamental challenges of mobile computing, especially relating to wireless communication. Others will take an application-driven approach, being designed to serve a novel purpose, and be adapted to the unique and varied challenges from their disparate domains. However, all are related through a unifying goal, to provide a seamless, enjoyable, and productive mobile experience. This dissertation takes view that by bringing together nontrivial enhancements across a selection of disparate-but-interrelated domains, the impact is synergistically stronger than the sum of each in isolation. Through their collective impact, these new "building blocks" can help lay a foundation to upgrade mobile technology beyond the expectations of early-adopters, and into seamless integration with all of our lives.</p> / Dissertation

This paper presents a fault-tolerant (fault tolerant) can enhance the communications capabilities, improve the reliability and efficiency of in smart grid signal transmission. Meter layout with PLC or ZigBee in any topology, meter adopt Minimum Spanning Tree algorithm to achieve shortest distance and lost cost in PLC; when device contain wireless receiver, meter adopt Hungarian algorithm can search nearest itself¡¦s device to receive device information. The paper propose two fault tolerant methods: static and dynamic methods. Static method is a meter transmit to another one with regular communication even if a meter tranfmit with ZigBee; dynamic method is a meter transmit another one, ZigBee has low priority according to cost function in effective communication range. The paper simulation in any 100m2 topology, randon produce 13 SmartUnit with different number of meters and coordinate, two fault tolerant method can achieve 100% fault coverage in single link fault case; but static method use FTGDB(Fault Tolerant Generalized De Bruijn algorithm) multiple fault coverage can achieve 43% with d=4 case; dynamic method use Kth shortest path algorithm multiple fault coverage can achieve 61% with d=4 case. In other words FTGDB has average 100 communication line allow average 43 communication line fault tolerant ability with d=4 case in 13 SmartHomeUnit; Kth shortest path algorithm has average 100 communication line allow average 61 communication line fault tolerant ability with d=4 case in 13 SmartHomeUnit. If after fault tolerant achievement, count to demand energy and delay time with PLC and ZigBee, then it can offer electric company information. Electric company evaluate electric cost¡Breal time price etc¡K The paper propose a online demand response method, the method is Online Priority Tree algorithm to be counted end device¡¦s rank priority according to device importance.

<p><!--st1\:*{behavior:url(#ieooui) } --><!--[endif]--> <!-- /* Font Definitions */ @font-face {font-family:Garamond; panose-1:2 2 4 4 3 3 1 1 8 3; mso-font-charset:0; mso-generic-font-family:roman; mso-font-pitch:variable; mso-font-signature:647 0 0 0 159 0;} /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0cm; margin-bottom:.0001pt; mso-pagination:widow-orphan; mso-layout-grid-align:none; punctuation-wrap:simple; text-autospace:none; font-size:12.0pt; mso-bidi-font-size:10.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman"; mso-ansi-language:EN-GB; mso-fareast-language:EN-US;} @page Section1 {size:612.0pt 792.0pt; margin:70.85pt 70.85pt 70.85pt 70.85pt; mso-header-margin:36.0pt; mso-footer-margin:36.0pt; mso-paper-source:0;} div.Section1 {page:Section1;} --></p><p>To implement a utility wireless sensor network, investigation of different wireless protocols has been performed. The protocols are Bluetooth, Wi-Fi, IEEE 802.15.4 and Zigbee. Consecutively literature studies have made it comprehensible to understand the function of the protocols that are suitable for development of wireless sensor networks. The importance of low cost, low power, reliable and high-quality properties for long distances are significant. IEEE 802.15.4 and Zigbee protocol are proper to implement as a wireless sensor network.</p><p> </p><p>To reduce the human efforts in the configuration of the system, a comfortable method is implemented to facilitate the procedure. The applied method is based on an automatic configuration of the system. The configuration and the decision taking are implemented in the software. The system is designed to avoid interference to other wireless networks with the possibilities of reconfiguration.</p><p>A uniform hardware and software design with separate functions of the system decided by a subsequent command for configuration is preferable. This imposes an advantage that increases the flexible potential of the system when a uniform solution is implemented.</p><p> </p><p>To support the basic communication principles and control of the system, a buffer implementation has been introduced. The functionality of decision taking is distributed, configured by system commands from the host system. Detecting of system commands requires a properly operating buffer management. In consideration to the power consumption in reference to battery utilizations, the settings of RF-module and microcontroller have a powerful impact to reduce the power consumption. All possibilities of hibernates and avoidance of unnecessarily transmitting, should be deactivated to minimize the power consumption.</p><p> </p>

Στην εποχή που ζούμε, η καθημερινότητα των πολιτών, από όλες σχεδόν τις πλευρές της, από την επαγγελματική και προσωπική της διάσταση έως τον τρόπο που επιλέγει πλέον κάποιος να διασκεδάζει και να κοινωνικοποιείται, είναι σε πολύ μεγάλο βαθμό εξαρτημένη από το νευραλγικό τομέα των επικοινωνιών. Διαπιστώνει κανείς πολύ εύκολα την ήδη εδώ και δεκαετίες, τεράστια διείσδυση των επικοινωνιών σε όλους τους παραγωγικούς τομείς της κοινωνίας, στους ίδιους τους μηχανισμούς της διακυβέρνησης και της ενημέρωσης. Το τεράστιο άλμα ωστόσο, πραγματοποιείται τα τελευταία χρόνια, με την ανάπτυξη των ασύρματων επικοινωνιών και διάφορων τεχνολογιών που προκύπτουν μέσα από επίπονη και πολύχρονη έρευνα. Κινητή τηλεφωνία, ασύρματα δίκτυα, πρόσβαση σε γρήγορο internet οπουδήποτε και οποτεδήποτε, είναι τεχνολογίες που έχουν αλλάξει δραματικά και ανεπιφύλακτα προς το καλύτερο, τις ζωές όλων μας. Στη παρούσα διπλωματική εργασία με τίτλο «Διερεύνηση τεχνικών παραμέτρων για βέλτιστη σχεδίαση συστημάτων τεχνολογίας Wi-Fi:», αφού πρώτα μελετήσουμε πλήρως το πρότυπο 802.11 ή κοινώς WiFi, όσο αφορά την αρχιτεκτονική του, τη δομή του και τις διάφορες εκδόσεις του, προχωράμε σε μια μελέτη γύρω από τα θεωρητικά μοντέλα διάδοσης της ηλεκτρομαγνητικής ακτινοβολίας σε εσωτερικούς χώρους με σκοπό να εξετάσουμε στη συνέχεια ένα τέτοιο πολύπλοκο περιβάλλον και τον τρόπο που συμπεριφέρεται το πρότυπο για μια συγκεκριμένη συχνότητα. Μέσω της μοντελοποίησης και της προσομοίωσης εκτιμάμε και αξιολογούμε τους παράγοντες που επηρεάζουν τη διάδοση αλλά και τυχόν καινούρια στοιχεία που μπορεί να προκύψουν. Στο πρώτο κεφάλαιο εισάγεται ο αναγνώστης στις ασύρματες επικοινωνίες με μια σύντομη ιστορική αναδρομή και την παρουσίαση των βασικών ασύρματων συσ τημάτων σήμερα. Στο κεφάλαιο δύο παρουσιάζεται πλήρως το πρότυπο 802.11. Αναπτύσσεται η αρχιτεκτονική του, η δομή του, το φυσικό του επίπεδο με τις τεχνικές μετάδοσης των διάφορων επικρατέστερων εκδόσεων του αλλά και οι λειτουργίες του επίπεδου MAC με τις παραμέτρους του. Προχωρώντας στο τρίτο κεφάλαιο, μελετάμε τους μηχανισμούς διάδοσης και τα φαινόμενα εξασθένισης του σήματος , κυρίως όμως γίνεται εκτενής αναφορά στα μοντέλα που περιγράφουν την ηλεκτρομαγνητική διάδοση σε περιβάλλον εσωτερικού χώρου, κάθως με βάση τα μοντέλα αυτά, γίνε ται η τελική αξιόγηση του πειραματικού μέρους της εργασίας. Στο τέταρτο κεφάλαιο παρουσιάζονται οι πειραματικές μας μετρήσεις, η τοπολογία και η διαδικασία με την οποία λήφθησαν. Πραγματοποιείται σύγκριση αυτών με τις προβλέψεις βασικών θεωρητικών μοντέλων, και μέσω προσομοίωσης που πραγματοποιήθηκε στο Matlab, εκτιμάται η απόκλιση των πειραματικών τιμών από τις θεωρητικές προβλέψεις. Στο τελευταίο κεφάλαιο παραθέτουμε τα γενικά συμπεράσματα που προέκυψαν από την πειραματική διαδικασία, αξιολογούμε τους παράγοντες που συνετέλεσαν στη λήψη των αποτελεσμάτων μας και αποφαινόμαστε για το καταλληλότερο μοντέλο στο περιβάλλον που εργαστήκαμε. / Nowadays, the citizen’s daily life from both the professional and personal point of view to the way somebody chooses to be socialized and get amused, is extremely dependent on the neuralgic field of communications. It becomes evident easily to anybody, the already for decades great penetration of communications to all the production sectors into society and the mechanisms of governess and mass media. However, the tremendous evolution is realized the very last years via the development of wireless communicat ions and the corresponding technologies that arise through arduous and extensive research. Mobile telephony, wireless networks, fast internet access anywhere and anytime, are technologies that has changed drastically and unreservedly our lives to the better. In this thesis, entitled “Investigation of Technical Parameters for Optimal design of WiFi Technology Systems”, after fully studying the 802.11 protocol, commonly referred as WiFi, regarding to its architecture, its structure, and its various versions, we proceed to a study of the theoretical indoor propagation models of electromagnetic radiation, in order to examine then such a complex environment and the behavior of the protocol for a specific frequency. Through modeling and simulation, we estimate and evaluate the factors that affect the propagation, but also any potential new information that may arise. The first chapter introduces to the reader the field of wireless communications and provides a historical overview of the basic wireless communication setups. In chapter two, protocol 802.11 is fully presented. Its architecture, its structure and its physical layer with the employed transmission techniques by its various predominant versions and also the functions of the MAC layer and its parameters are described. Chapter three discusses the transmission methods and the signal attenuation effect, with emphasis on the models that describe the electromagnetic transmission in enclosed spaces, as these models are used for the evaluation of the experimental part of this thesis. Chapter four contains the experimental part of this thesis and presents the topology and the exact procedure of the measurement setup. The obtained measurements are compared to the predicted ones using existing theoretical models via simulations that performed in Matlab and the prediction error is then computed and discussed. In the last chapter, we present the general conclusions derived from the measurement procedure, we evaluate the factors that contributed to the derivation of our results and we determine the most appropriate model for the environment in which we worked.