The demand for higher data rates for indoor and cell-edge users led to evolution of small cells. LTE femtocells, one of the small cell categories, are low-power low-cost mobile base stations, which are deployed within the coverage area of the traditional macro base station. The cross-tier and co-tier interferences occur only when the macrocell and femtocell share the same frequency channels. Open access (OSG), closed access (CSG), and hybrid access are the three existing access-control methods that decide users' connectivity to the femtocell access point (FAP). We define a network performance function, network productivity, to measure the traffic that is carried successfully. In this dissertation, we evaluate call mobility in LTE integrated network and determine optimized network productivity with variable call arrival rate in given LTE deployment with femtocell access modes (OSG, CSG, HYBRID) for a given call blocking vector. The solution to the optimization is maximum network productivity and call arrival rates for all cells. In the second scenario, we evaluate call mobility in LTE integrated network with increasing femtocells and maximize network productivity with variable femtocells distribution per macrocell with constant call arrival rate in uniform LTE deployment with femtocell access modes (OSG, CSG, HYBRID) for a given call blocking vector. The solution to the optimization is maximum network productivity and call arrival rates for all cells for network deployment where peak productivity is identified. We analyze the effects of call mobility on network productivity by simulating low, high, and no mobility scenarios and study the impact based on offered load, handover traffic and blocking probabilities. Finally, we evaluate and optimize performance of fractional frequency reuse (FFR) mechanism and study the impact of proposed metric weighted user satisfaction with sectorized FFR configuration.

This diploma thesis deals with the use of freely available data sets to estimate the signal strength in localities where measurements are missing. This work aimed to use interpolation and regression methods to estimate as accurately as possible the possible signal coverage in a given locality. First, data sets were analyzed, based on results, a test model for various methods has been created. The methods with the best results have been implemented on real data sets containing thousands of measurements. At the end of the work, accurate estimates are commented and circumstances to reduce the deviation of the measured and calculated values are specified.

The thesis describes the 2G, 3G and 4G mobile systems with a focus on the user plane. It decipt the problem of key performance indicators focusing on the characteristics of the user plane. It contains analysis of the basic data transmission services and requirements for their quality. The thesis also describes the user plane protocol stacks.

The diploma thesis „Mechanisms modelling of multi access into mobile wireless network“ is focusing the wireless network. The diploma thesis contains basic network topology of wireless standard 802.11g and utilizes key identificators of mobile node in dependency on the distance and collision controlling function for simulation purposes. In the next part of this thesis is created LTE mobile network topology, which serves for finding key identificators. In the last part is created offload topology containing both - 802.11g and LTE network. As the result are implemented offloading algorithms, which ensure data traffic switching based on comparing 802.11g and LTE key identificators. Automatically generated and shown figures providing the key statistics are the main output of this thesis.

Dizertační práce se zabývá zpracováním signálu fyzických řídicích kanálů systému LTE a vyšetřováním bitové chybovosti při přenosu řídicí informace z vysílače do přijímače v závislosti na podmínkách příjmu. Práce je rozdělena do dvou hlavních částí. První část práce je zaměřena na simulaci přenosu řídicí informace LTE v základním pásmu. Jsou zde prezentovány vytvořené simulátory řídicích kanálů ve směru uplink i downlink. Simulace jsou provedeny pro všechny druhy nastavení systému a základní modely přenosového prostředí. Jsou zde popsány výsledky vlivu použití MIMO technologií na kvalitu příjmu řídicí informace především v únikových kanálech. Druhá část práce je zaměřena na možnost nasazení systému LTE ve sdíleném pásmu ISM (2.4 GHz). Jsou zde představeny základní koncepce použití, na jejichž základě je vytvořen scénář simulací. Kapitola dále popisuje tvorbu simulátoru koexistence LTE a systému Wi-Fi v přeneseném pásmu ISM 2.4GHz. Jsou zde uvedeny výsledky simulací koexistence LTE a rušivého systému Wi-Fi provedených dle vytvořeného scénáře. Výsledky simulací koexistence LTE a Wi-Fi jsou ověřeny měřením v laboratorních podmínkách. Toto porovnání je důležité z hlediska optimalizace simulátoru koexistence. Dle výsledků obou typů simulací a měření jsou stanovena provozní doporučení, která mají přispět k bezpečnému a spolehlivému vysílání a příjmu řídicích informací LTE i při nepříznivých podmínkách příjmu.

The aim of this thesis is acquaintance with the EPS system of LTE and IMS subsystem. The thesis is aimed on analysis of the control procedures related to operations between the terminal and the packet core network of the fourth generation such as logging into the system, user authentication, change the viewing area, handover and disconnection from the network.

The aim of the work is the radio access network of mobile networks second, third and fourth generation. The main objective is a description of the radio access network of the second, third and fourth generation, their elements, interfaces and signaling procedures. The next part describes the emergency services and the architecture of the fourth generation mobile networks. The practical part is then devoted to identify actions needed to prepare radio access network to testing emergency services, identify actions needed to conversion of transport protocol fixed part of the radio access network from IPv4 to IPv6 and describe the intervention to radio access network to change the active segment of the core network.

<div>Cellular networks are an indispensable part of a nation's critical infrastructure. They not only support functionality that are critical for our society as a whole (e.g., business, public-safety message dissemination) but also positively impact us at a more personal level by enabling applications that often improve our quality of life (e.g., navigation). Due to deployment constraints and backward compatibility issues, the various cellular protocol versions were not designed and deployed with a strong security and privacy focus. Because of their ubiquitous presence for connecting billions of users and use for critical applications, cellular networks are, however, lucrative attack targets of motivated and resourceful adversaries. </div><div><br></div><div></div><div>In this dissertation, we investigate the security and privacy of 4G LTE and 5G protocol designs and deployments. More precisely, we systematically identify design weaknesses and implementation oversights affecting the critical operations of the networks, and also design countermeasures to mitigate the identified vulnerabilities and attacks. Towards this goal, we developed a systematic model-based testing framework called LTEInspector. LTEInspector can be used to not only identify protocol design weaknesses but also deployment oversights. LTEInspector leverages the combined reasoning capabilities of a symbolic model checker and a cryptographic protocol verifier by combining them in a lazy fashion. We instantiated \system with three critical procedures (i.e., attach, detach, and paging) of 4G LTE. Our analysis uncovered 10 new exploitable vulnerabilities along with 9 prior attacks of 4G LTE all of which have been verified in a real testbed. Since identifying all classes of attacks with a unique framework like \system is nearly impossible, we show that it is possible to identify sophisticated security and privacy attacks by devising techniques specifically tailored for a particular protocol and by leveraging the findings of LTEInspector. As a case study, we analyzed the paging protocol of 4G LTE and the current version of 5G, and observed that by leveraging the findings from LTEInspector and other side-channel information and by using a probabilistic reasoning technique it is possible to mount sophisticated privacy attacks that can expose a victim device's coarse-grained location information and sensitive identifiers when the adversary is equipped only with the victim's phone number or other soft-identity (e.g., social networking profile). An analysis of LTEInspector's findings shows that the absence of broadcast authentication enables an adversary to mount a wide plethora of security and privacy attacks. We thus develop an attack-agnostic generic countermeasure that provides broadcast authentication without violating any common-sense deployment constraints. Finally, we design a practical countermeasure for mitigating the side-channel attacks in the paging procedure without breaking the backward compatibility.</div>

In recent years, the advent of Long Term Evolution (LTE) technology as a prominent component of 4G networks and future 5G networks, has paved the way for fast and new mobile web access and application services. With these advantages come some security concerns in terms of attacks that can be launched on such networks. This thesis focuses on the impact of the mobile botnet on LTE networks by implementing a mobile botnet architecture that initiates a Distributed Denial of Service (DDoS) attack. First, in the quest of understanding the mobile botnet behavior, a correlation between the mobile botnet impact and different mobile device mobility models, is established, leading to the study of the impact of the random patterns versus the uniform patterns of movements on the mobile botnet’s behavior under a DDoS attack. Second, the impact of two base transceiver station selection mechanisms on a mobile botnet behavior launching a DDoS attack on a LTE network is studied, the goal being to derive the effect of the attack severity of the mobile botnet. Third, an epidemic SMS-based cellular botnet that uses an epidemic command and control mechanism to initiate a short message services (SMS) phishing attack, is proposed and its threat impact is studied and simulated using three random graphs models. The simulation results obtained reveal that (1) in terms of users’ mobility patterns, the impact of the mobile botnet behavior under a DDoS attack on a victim web server is more pronounced when an asymmetric mobility model is considered compared to a symmetric mobility model; (2) in terms of base transceiver station selection mechanisms, the Distance-Based Model mechanism yields a higher threat impact on the victim server compared to the Signal Power Based Model mechanism; and (3) under the Erdos-and-Reyni Topology, the proposed epidemic SMS-based cellular botnet is shown to be resistant and resilient to random and selective cellular device failures. / Graduate

Although positioning has been one of the main target study areas in mobile communication in the last decade, it still receives strong attention in recent years focusing more on the indoor users. Nowadays, a wide range of different methods are available to estimate the position of the target user under certain circumstances. One of these methods is Uplink Time Difference of Arrival (UTDoA), which has been defined in 3GPP Release 11 for Long Term Evolution (LTE) networks, and is the focus of this master thesis. In Uplink based positioning, to estimate the position of a User Equipment (UE), the UE only needs to generate and transmit the reference signal and the main computational effort of time estimation, is moved from the UE towards the network side. This might be one advantage compared to Observed Time Difference of Arrival (OTDoA), while further performance properties of UTDoA in LTE are investigated in the course of this master thesis. In parallel with the 3GPP Study Item on Indoor Positioning which mainly was based on downlink OTDoA, this thesis studies on the potential use of UTDoA in LTE under the same type of agreed deployment scenarios and simulation parameters. For time estimation based on the Sounding Reference Signals (SRSs), the uplink channel has been modeled and simulated. Finally, the position estimation of the UE is derived by multilateration techniques using the time/distance estimations of the received SRS at each eNodeB. The metrics of positioning results are based on Cumulative Distribution Functions (CDF) of horizontal and vertical positioning error. The study shows that reasonable horizontal position accuracy can be achieved, while a number of pico cells are added to the network to enhance the macro-only scenario. However, this positive effect could not be observed in vertical position estimation. A further investigated aspect is the influence by other active UEs considered as interference. The outcome shows, that the accuracy is strongly and negatively affected by introducing interference. A final observation focuses on the SRS bandwidth and that for bandwidths below 10 MHz additional degradations in performance are seen. / Trots att positionering har varit ett av huvudmålen för forskning inom mobil kommunikation under det senaste decenniet, får det fortfarande mycket uppmärksamhet och under de senaste åren har forskningen fokuserats mer på inomhusanvändare. Idag finns en mängd olika metoder för att estimera positionen för en specifik användare under vissa omständigheter. En av dessa metoder är Uplink Time Difference of Arrival (UTDoA) som har definierats i 3GPP Release 11 för Long Term Evolution (LTE)-nätverk och är fokus för detta examensarbete. I positionering baserad på upplänken, vilken används för att skatta positionen för en User Equipment (UE), behöver UE:n bara generera och sända en referenssignal och den huvudsakliga beräkningskraften för tidsestimeringen flyttas från UE:n till nätsidan. Detta kan vara en fördel jämfört med Observed Time Difference of Arrival (OTDoA), detta examensarbete undersöker ytterligare prestandaegenskaper hos UTDoA i LTE. Parallellt med 3GPP:s studie för inomhuspositionering, som huvudsakligen baseras på nerlänk OTDoA, studerar denna avhandling den potentiella användningen av UTDoA i LTE med samma typ av överenskomna scenarier och simuleringsparametrar. För tidsuppskattning baserad på Sounding Reference Signals (SRSs) har kanalen upplänkmodellerats och simulerats. Slutligen är positionsestimeringen av UE:n härledd genom multilaterationstekniker med hjälp av tids- och distansestimeringar av de mottagna SRS vid varje eNodeB. De mått som används för positioneringsresultat baseras på kumulativ fördelningsfunktion av det horisontella och vertikala positioneringsfelet. Studien visar att en rimlig noggrannhet kann uppnås i den horisontella dimensionen då ett antal pico-celler adderas till nätverket för att förbättra makroscenariot. Denna positiva effekt kunde emellertid inte observeras i den vertikala positionsestimeringen. En ytterligare undersökt aspekt är påverkan av andra aktiva UEs, som betraktas som interferens. Resultaten visar att noggrannheten är starkt negativt påverkad då störningar i form av interferens införs. En slutlig observation fokuserar på bandbredden av SRS och det visar på försämringar i prestanda för bandbredder under 10 MHz.