Security protocols are ubiquitously used in various applications with the intention to ensure secure and private communication. To achieve this goal, a mechanism offering reliable and systematic protocol verification is needed. Accordingly, a major interest in academic research on formal methods for protocol analysis has been apparent for the last two decades. Such methods formalize the operational semantics of a protocol, laying the base for protocol verification with automatic model checking tools. So far, little work in this field has focused on protocol standardization. Within this thesis a security analysis of a novel Authenticated Key-Exchange (AKE) protocol for secure association handover between two Long-Term Evolution (LTE) base stations (which support dual-connectivity) is carried out by applying two state-of-the-art tools for automated model checking (Scyther and Tamarin Prover). In the course of this a formal protocol model and tool input models are developed. Finally, the suitability of the used tools for LTE protocol analysis is evaluated. The major outcome is that none of the two applied tools is capable to accurately model and verify the dual-connectivity protocol in such detail that it would make them particularly useful in the considered setting. The reason for this are restrictions in the syntax of Scyther and a degraded performance of Tamarin when using complex protocol input models. However, the use of formal methods in protocol standardization can be highly beneficial, since it implies a careful consideration of a protocol’s fundamentals. Hence, formal methods are helpful to improve and structure a protocol’s design process when applied in conjunction to current practices. / Säkerhetsprotokoll används i många typer av applikationer för att säkerställa säkerhet och integritet för kommunikation. För att uppnå detta mål behövs en behövs mekanismer som tillhandahåller pålitlig och systematisk verifiering av protokollen. Därför har det visats stort akademiskt intresse för forskning inom formell verifiering av säkerhetsprotokoll de senaste två decennierna. Sådana metoder formaliserar protokollsemantiken, vilket lägger grunden till automatiserad verifiering med modellverifieringsverktyg. Än så la¨nge har det inte varit stort focus på praktiska tilla¨mpningar, som t.ex. hur väl metoderna fungerar för de problem som dyker upp under en standardiseringsprocess. I detta examensarbete konstrueras en formell modell för ett säkerhetsprotokoll som etablerar en säkerhetsassociation mellan en terminal och två Long-Term Evolution (LTE) basstationer i ett delsystem kallat Dual Connectivity. Detta delsystem standardiseras för närvarande i 3GPP. Den formella modellen verifieras sedan med bästa tillgängliga verktyg för automatiserad modellverifiering (Scyther och Tamarin Prover). För att åstadkomma detta har den formella modellen implementerats i inmatningsspråken för de två verktygen.  Slutligen ha de två verktygen evaluerats. Huvudslutsatsen är att inget av de två verktygen tillräckligt väl kan modellera de koncept där maskinstödd verifiering som mest behövs. Skälen till detta är Scythers begränsade syntax, och Tamarins begränsade prestanda och möjlighet att terminera för komplexa protokollmodeller. Trots detta är formella metoder andvändbara i standardiseringsprocessen eftersom de tvingar fram väldigt noggrann granskning av protokollens fundamentala delar. Därför kan formella metoder bidra till att förbättra strukturen på protokollkonstruktionsprocessen om det kombineras med nuvarande metoder.

The usage of UAVs (Unmanned Aircraft Vehicle) is soaring, not just for hobbyists but increasingly for a range of professional and civil applications. Some of the more sophisticated applications that have high data usage and long-range flight requirements are being developed now. The range and capability of typical wireless connectivity technologies are not enough for such applications. Connecting UAVs to the mobile network is a solution. There are lots of benefits which mobile network can provide for UAVs and UTM (Unmanned Aircraft System Traffic Management). However, the anticipation of UAVs was not considered at first in network planning, which creates unexpected coverage conditions. The introduction of UAVs impacts LTE (Long Term Evolution) network in several ways and the network coverage and capacity of UAVs at low altitude is significantly different from that of terrestrial UEs. The thesis work includes investigation about how UAVs impact LTE network and how mobile network coverage and capacity for UAVs change when other factor changes. The impact of methods to enhance the mobile network for UAVs would also part of the research. In this work, a successful simulation in order to investigate UAV’s situation while using 4G LTE cellular networks is developed. In order to properly test the developed framework for a range of different inputs, various generic scenarios were successfully developed and executed. Using this simulation, we have shown that UAV’s network situation is affected by 2 parameters: the height of UAV and the load of the eNodeBs (Evolved Node B). We have successfully demonstrated that UAV at higher attitude may cause more serious network condition in the suburban area compared with the case in the urban area. Finally, an interference mitigation technique: antenna beam selection is applied and tested. We show that it can improve the network condition for UAV at a higher altitude. Some improvements to the model could be a modeling of inter-cell interference and multipath effects. Models of weather condition in UAV’s flying space would also greatly improve the framework. Besides a scheme for modulation and bit error calculation could be used to build a more generic model. In the thesis, antenna propagation and gain models are not perfect, so more accurate model would also be a great improvement. Only antenna beam selection is tested in this thesis and the implementation does not include antenna mechanical design and model building. For further research, more methods like interference cancellation, power control and inter-cell interference coordination can be tested in both simulation and hardware. / Användningen av UAV(Unmanned Aircraft Vehicle): er är stigande, inte bara för hobbyister utan allt mer för en rad professionella och civila applikationer. Några av de mer sofistikerade applikationerna som har hög dataanvändning och krav på lång räckvidd utvecklas nu. Räckvidden och kapaciteten för typiska trådlösa anslutningstekniker räcker inte för sådana applikationer. Att ansluta UAV: er till mobilnätet är en lösning. Det finns många fördelar som mobilnätet kan ge för UAV: er och UTM (Unmanned Aircraft System Traffic Management). Förväntningen på UAV: er beaktades dock inte först i nätverksplanering, vilket skapar oväntade täckningsförhållanden.Införandet av UAV: er påverkar LTE-nätverk (Long Term Evolution) på flera sätt och nätverkets täckning och kapacitet för UAV: er på låg höjd skiljer sig väsentligt från markbundna UE: er.Examensarbetet inkluderar utredning om hur UAV: er påverkar LTE-nätverk och hur mobilnätstäckning och kapacitet för UAV: er förändras när andra faktorer ändras. Effekten av metoder för att förbättra mobilnätverket för UAV: er skulle också vara en del av forskningen. I detta arbete utvecklas en framgångsrik simulering för att undersöka UAV: s situation med användning av 4G LTE-mobilnät. För att korrekt testa det utvecklade ramverket för en rad olika ingångar, utvecklades och genomfördes olika generiska scenarier. Med denna simulering har vi visat att UAVs nätverkssituation påverkas av två parametrar: UAV: s höjd och belastningen på eNodeBs (Evolved Node B). Vi har framgångsrikt visat att UAV vid högre inställning kan orsaka allvarligare nätverkstillstånd i förortsområdet jämfört med fallet i stadsområdet. Slutligen tillämpas och testas en interferensbegränsande teknik: val av antennstråle. Vi visar att det kan förbättra nätverksvillkoret för UAV på högre höjd. Några förbättringar av modellen kan vara modellering av inter-cellstörningar och flervägseffekter. Modeller av väderförhållanden i UAV: s flygutrymme skulle också förbättra ramverket kraftigt. Förutom ett schema för modulering och beräkning av bitfel skulle kunna användas för att bygga en mer generisk modell. I avhandlingen är antennutbredningsoch förstärkningsmodeller inte perfekta, så en mer exakt modell skulle också vara en stor förbättring. Endast val av antennstråle testas i denna avhandling och implementeringen inkluderar inte antennmekanisk design och modellbyggnad. För ytterligare forskning kan fler metoder som interferensavbrott, effektkontroll och inter-cell-interferenskoordination testas i både simulering och hårdvara.

The fourth generation cellular mobile broadband, Long-Term Evolution (LTE), provides high speed Internet via Internet Protocol (IP). Today’s wireless infrastructure paves the way to a connected society where high speed Internet is seamlessly available at all times for anyone to use. To achieve this, a mobile service subscriber can no longer be bound to a single network provided by a single operator. Thus, roaming constitutes a key pillar in shaping the connected society Local Breakout (LBO) Voice over Long-Term Evolution (VoLTE) roaming enables a mobile service subscriber to breakout from its home network, and to use network services in a visited network. LBO requires control signalling and user data to be routed over several Public Land Mobile Networks (PLMNs), thus making mobile service subscriber’s the subject of Lawful Intercept (LI) across multiple networks. This thesis project investigates the possibility of using Multimedia Internet KEYing (MIKEY) and Secure Real-Time Transport Protocol (SRTP) to encrypt the payload of VoLTE media packets. More specifically, a Law Enforcement Monitoring Provider (LEMP) is designed, implemented, and evaluated. LEMP is deployed within a cell phone and serves to distribute cryptographic key shares to Trusted Third Parties (TTPs), i.e. multiple escrow agents, entrusted to store these cryptographic key shares. The result preserves the requirements for LI despite the fact that there may be multiple network operators involved. Moreover, the experiments show that the distribution time depends primarily on network latency rather than the time required to split the cryptographic key in chunks; hence the approach is usable in practice. / Den fjärde generationens mobila bredband, Long-Term Evolution (LTE), möjliggör användandet av höghastighetsinternet över Internet Protocol (IP). Dagens trådlösa infrastrukturer banar väg för ett fritt och lättillgängligt digitalt samhälle där alla kan vara uppkopplade samtidigt. För att uppnå global trådlös infrastruktur måste mobilabonnenten ha möjlighet att utnyttja flera andra trådlösa nätverk än det nätverk som teleoperatören binder dem till. Därför utgör fri roaming en viktig del i utvecklingen av framtidens globala trådlösa infrastrukturer. Local Breakout (LBO) Voice over Long-Term Evolution (VoLTE) är en roamingarkitektur som gör det möjligt för en mobilabonnent att kopplas upp från en teleoperatörs nät till en annans. LBO kräver att kontrollsignaler och användardata skickas mellan flera operatörer innan trafiken når sitt mål, och därmed utsätts mobilabonnenten för laglig avlyssning av elektronisk information på flera platser samtidigt. Det här examensarbetet undersöker möjligheten att använda Multimedia Internet KEYing (MIKEY) och Secure Real-Time Transport Protocol (SRTP) för att kryptera mediatrafik i VoLTE. Under arbetets gång utvecklas och utvärderas en Law Enforcement Monitoring Provider (LEMP). LEMP är placerad i en mobiltelefon och distribuerar delar av krypteringsnycklar till flera betrodda tredje parter (till flera escrow agents). Detta gör det möjligt att uppfylla kraven för laglig avlyssning av elektronisk information även när flera teleoperatörer avlyssnar användardata och kontrollsignaler. Resultatet visar att distribueringstiden primärt beror på nätverkslatens, och inte på den tid det tar att fördela krypteringsnyckeln i mindre delar. Därför kan den här metoden användas i praktiken.

La presente tesis aborda la problemática de la convivencia entre las redes de la televisión digital terrestre y móvil de cuarta generación en la banda del primer dividendo digital (banda de 700 MHz), en Sudamérica. Además, se proponen dos potenciales casos de uso de compartición de espectro para el uso futuro de la banda de televisión después de los dividendos digitales, como modo de acceso eficiente y flexible para el uso del espectro radioeléctrico. Para garantizar la convivencia entre las tecnologías de televisión y móviles en la banda del primer dividendo digital en Sudamérica, se evalúa tanto el impacto de las redes móviles sobre las de televisión, así como el caso contrario, las redes de televisión sobre las móviles, teniendo en cuenta los parámetros técnicos de operación de cada una de las redes implicadas, los cuales son definidos por organismos de estandarización o parámetros reales de redes implementadas por cada país. Dentro de los parámetros técnicos de operación que se definieron para las redes podemos citar: márgenes de protección entre las señales de televisión y móviles; distancias de protección entre el transmisor interferente y el receptor víctima; banda de guarda requeridas entre las dos tecnologías; límites de emisiones interferentes fuera de banda; niveles de atenuación adicionales en las máscaras espectrales; evaluación de técnicas de mitigación de interferencias, entre otros. Es importe resaltar, que las principales diferencias entre los estudios de convivencia en Sudamérica respecto a Europa son: la banda de guarda en Sudamérica son 5 MHz mientras en Europa son 9 MHz; el ancho de banda de un canal de televisión en Sudamérica es 6 MHz respecto a 8 MHz en Europa; el estándar de televisión adoptados en casi toda Sudamérica es ISDB-Tb, a excepción de Colombia que adopto DVB-T2. Asimismo, en el ámbito de esta tesis, se proponen dos potenciales casos de estudio para el uso futuro de la banda de TV, promoviendo la compartición de espectro como un modo de acceso eficiente: El primer caso de estudio, propone un nuevo concepto de espacios en blanco llamado µ-TV-White-Space, los cuales son aquellas zonas geográficas en los interiores de una vivienda y/o oficina que no son cubiertas por el servicio de televisión digital terrestre, ya sea por la ausencia de cobertura o por obstáculos. El escenario propuesto es una red DVB-T2 ofreciendo cobertura en recepción fija sobre tejado, como servicio primario, y, femtoceldas LTE-A en interiores de un hogar u oficina, como servicio secundario. Los resultados obtenidos proporcionan restricciones técnicas para que las femtoceldas LTE-A puedan operar correctamente en espectro compartido con los servicios de televisión. Específicamente, se define la Potencia Isotrópica Radiada Equivalente (PIRE) máxima que podrían transmitir las femtoceldas, en función de la separación en frecuencia con los servicios de televisión. El segundo caso de estudio, propone el uso de los espacios en blanco para la compartición de espectro entre los servicios de internet de las cosas bajo el estándar NB-LTE-IoT, como servicio secundario, y servicios de televisión digital terrestre bajo el estándar DVB-T2, como servicio primario. Se define la máxima potencia transmisible por los nodos y dispositivos IoT sin interferir al servicio primario. Además, se evalúa el impacto del ciclo de trabajo de los dispositivos considerando que existirá diversidad de aplicaciones. La importancia de esta propuesta se fundamenta en dos contribuciones: por un lado, se optimiza el uso de la banda de televisión mediante el acceso secundario de dispositivos de baja potencia en los espacios en blanco, siempre garantizando los servicios de televisión, como servicio primario, por otro lado, se contribuye con nuevas frecuencias para las tecnologías móviles de última generación, con el objetivo de aumentar la capacidad de las redes que soportarán tanto / This thesis deals with the issue about coexistence between television and fourth generation mobile networks within the band of the first digital dividend (700 MHz band), in South America. Moreover, two potential cases of sharing spectrum for future use of the television band after the digital dividends are suggested as an efficient and flexible way for usage of the radio spectrum. In order to ensure the coexistence between the television and mobile technologies within the band of the first digital dividend in South America, the impact of the mobile networks as well as the opposite case are assessed. The technical operation parameters for each of the involved networks defined by standardizing organisms or real parameters from implemented networks in each country are considered. Among the technical parameters that were defined for the networks, we can mention: protection ratio between television and mobile signals; protection distances between the interfering transmitter and the victim receiver; required guard bands between both technologies; maximum power of the interfering out-of-band emissions in adjacent channels; additional attenuation levels in the spectrum emission mask in transmission and reception; assessing of interference mitigation techniques, among others. It is important to highlight that the main differences between the coexistence studies for South America and Europe are: the guard bands in South America are 5 MHz whereas in Europe are 9 MHz; bandwidth for a channel in South America is 6 MHz in contrast with the 8 MHz of Europe; the television standard adopted in almost all South America is ISDB-Tb, except Colombia and the French Guiana, which adopted DVB-T2. Additionally, within the scope of this thesis, two potential study cases for future usage of the TV band are proposed, promoting sharing spectrum as an efficient access way: The first study we go a step beyond coexistence, since the aim is to exploit the unused radio spectrum in those geographical zones that are not covered because the useful signal is obstructed by the environment or it has a limited coverage by the network design. Those areas can be called "micro-TVWS" (µ-TV-White-Space). The most representative cases of our definition of µ-TV-White-Space are those indoor environments in areas where DTT received power is below the required sensitivity because a TV channel is broadcasted to rooftop reception. The proposed scenario considers a DTT network offering fixed rooftop reception as a primary service, and a LTE-A femtocell giving coverage within the interior of a home or office as a secondary service. Our results provide the technical restrictions of the LTE-A Femtocell, mainly on the maximum allowable Effective Isotropic Radiated Power (EIRP) that could transmit on the DTT band in terms of carrier separation, from co-channel to adjacent band. The second study case, suggests the use of white spaces for spectrum sharing among the Internet of Things (IoT) services, under the NB-LTE-IoT standard, as secondary service, and digital terrestrial television services under the DVB-T2 standard, as primary service. The maximum transmissible power by the nodes and IoT devices without interfering the primary service is defined. Besides, the impact of the duty cycle of the devices is assessed considering that there will be a great diversity of applications, and thus, a great diversity of operation requirements. The significance of this proposal is due to two contributions: on the aone hand, the usage of the television band is optimized through secondary access of low power devices within the white spaces, always ensuring television services as primary service. On the other hand, new frequencies for last generation mobile technologies are given, with the aim at increasing the network capacity, which will bear mobile services as well as IoT, regarding the high challenge of offering connectivity to millions of devices during the next decade. / La present tesi aborda la problemàtica de la convivència entres les xarxes de la televisió digital terrestre i mòbil de quarta generació en la banda del primer dividend digital (banda de 700 MHz), en Sud-Amèrica. A més, es proposen dos potencials casos d'ús compartit d'espectre per a l'ús futur de la banda de televisió després dels dividends digitals, com a mode d'accés eficient i flexible per a l'ús de l'espectre radioelèctric. Per tal de garantir la convivència entre les tecnologies de televisió i mòbils en la banda del primer dividend digital en Sud-Amèrica, s'avalua tant l'impacte de les xarxes mòbils sobre les de televisió, com el cas contrari, les xarxes de televisió sobre les mòbils, tenint en compte els paràmetres tècnics d'operació de cadascuna de les xarxes implicades, els quals són definits per organismes d'estandardització o paràmetres reals de xarxes implementades per cada país. Dins dels paràmetres tècnics d'operació que es van definir per a les xarxes podem citar: marges de protecció entre els senyals de televisió i mòbils; distàncies de protecció entre el transistor interferent i el receptor víctima; banda de guarda entre ambdós tecnologies; límits de les emissions interferents fora de banda; nivells d'atenuació addicionals en les màscares espectrals; avaluació de tècniques de mitigació d'interferències, entre d'altres. És important destacar, que les principals diferències entre els estudis de convivència en Sud-Amèrica respecte d'Europa són: la banda de guarda en Sud-Amèrica són 5 MHz mentre que a Europa són 9 MHz; l'amplària de banda d'un canal de televisió en Sud-Amèrica és de 6 MHz respecte dels 8 MHz a Europa; l'estàndard de televisió adoptat en quasi tota Sud-Amèrica és ISDB-Tb, excepte Colòmbia i la Guaiana Francesa que van adoptar DVB-T2. A Europa quasi tots els països tenen adoptats els estàndards DVB-T de primera i segona generació. Així mateix, en l'àmbit de la tesi, es proposen dos potencials casos d'estudi per a l'ús futur de la banda de TV, de manera que es promoga la compartició d'espectre com un mode d'accés eficient: El primer cas d'estudi, proposa un nou concepte d'espais en blanc anomenat µ-TV-White-Space, els quals són aquelles zones geogràfiques que no són cobertes pel servei de televisió digital terrestre, ja siga per l'absència de cobertura o per obstacles. L'escenari proposat és una xarxa DVB-T2 que ofereix cobertura en recepció fixa sobre terrat, com a servei primari, i femtocel·les LTE-A en interiors d'una llar o oficina, com a servei secundari. Els resultats obtinguts proporcionen restriccions tècniques per tal que les femtocel·les LTE-A puguen operar correctament en espectre compartit amb els serveis de televisió. Específicament, es defineix la Potència Isotròpica Radiada Equivalent (PIRE) màxima que podrien transmetre les femtocel·les, en funció de la separació en freqüència amb els serveis de televisió. El segon cas d'estudi, proposa l'ús d'espais en blanc per a la compartició d'espectre entre els serveis d'internet de les coses (Internet of Things o IOT, en anglès), sota l'estàndard NB-LTE-IoT, com a servei secundari, i serveis de televisió digital terrestre sota l'estàndard DVB-T2, com a servei primari. Es defineix la màxima potència transmissible pels nodes i dispositius IoT sense interferir al servei primari. A més, s'avalua l'impacte del cicle de treball dels dispositius considerant que existirà diversitat d'aplicacions, i, per tant, diversitat de requeriments d'operació. La importància d'aquesta proposta es fonamenta en dues contribucions: per una banda, s'optimitza l'ús de la banda de televisió mitjançant l'accés secundari de dispositius de baixa potència als espais en blanc, sempre garantint els serveis de televisió, com a servei primari. Per altra banda, es contribueix amb noves freqüències per a les tecnologies mòbils d'última generació, amb l'objectiu d'a / Martínez Pinzón, G. (2018). Compartición del Espectro Radioeléctrico entre Tecnologías Inalámbricas de Última Generación en la Banda de la Televisión Digital Terrestre [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/102644

The architecture of mobile networks has dramatically evolved in order to fulfill the growing demands on wireless services and data. The radio resources, which are used by the current mobile networks, are limited while the users demands are substantially increasing. In the future, tremendous Internet applications are expected to be served by mobile networks. Therefore, increasing the capacity of mobile networks has become a vital issue. Heterogeneous networks (HetNets) have been considered as a promising paradigm for future mobile networks. Accordingly, the concept of small cell has been introduced in order to increase the capacity of the mobile networks. A femtocell network is a kind of small cell networks. Femtocells are deployed within macrocells coverage. Femtocells cover small areas and operate with low transmission power while providing high capacity. Also, UEs can be offloaded from macrocells to femtocells. Thus, the capacity can be increased. However, this will introduce different technical challenges. The interference has become one of the key challenges for deploying femtocells within a certain macrocells coverage. Undesirable impact of the interference can degrade the performance of the mobile networks. Therefore, radio resource management mechanisms are needed in order to address key challenges of deploying femtocells. The objective of this work is to introduce radio resource control approaches, which are used to increase mobile networks' capacity and alleviate undesirable impact of the interference. In addition, proposed radio resource control approaches ensure the coexistence between macrocell and femtocells based on LTE-Advanced environment. Firstly, a novel mechanism is proposed in order to address the interference challenge. The proposed approach mitigates the impact of interference based on controlling radio sub-channels' assignment and dynamically adjusting the transmission power. Secondly, a dynamic strategy is proposed for the FFR mechanism. In the FFR mechanism, the whole spectrum is divided into four fixed sub-channels and each sub-channel is assigned for a different sub-area after splitting the macrocell coverage area into four sub-areas. The objective of the proposed scheme is to divide the spectrum dynamically based on the QoS indicators for each sub-area. Lastly, a novel packet scheduling scheme is proposed to improve the performance of femtocell networks. The proposed scheduling strategy assigns radio resources based on two objectives: increasing the network capacity and achieving better fairness among attached UEs.

Wireless communication networks have evolved continuously over the last four decades in order to meet the traffic and security requirements due to the ever-increasing amount of traffic. However this increase is projected to be massive for the fifth generation of wireless networks (5G), with a targeted capacity enhancement of 1000× w.r.t. 4G networks. This enhanced capacity is possible by a combination of major approaches (a) overhaul of some parts and (b) elimination of overhead and redundancies of the current 4G. In this work we focus on OFDM reference signal or pilot tones, which are used for channel estimation, link adaptation and other crucial functions in Long-Term Evolution (LTE). We investigate two aspects of pilot signals pertaining to its evolution - (a) impact of targeted interference on pilots and its mitigation and (b) adaptation of pilot patterns to match the channel conditions of the user. We develop theoretical models that accurately quantify the performance degradation at the user’s receiver in the presence of a multi-tone pilot jammer. We develop and evaluate mitigation algorithms to mitigate power constrained multi-tone pilot jammers in SISO- and full rank spatial multiplexing MIMO-OFDM systems. Our results show that the channel estimation performance can be restored even in the presence of a strong pilot jammer. We also show that full rank spatial multiplexing in the presence of a synchronized pilot jammer (transmitting on pilot locations only) is possible when the channel is flat between two pilot locations in either time or frequency. We also present experimental results of multi-tone broadcast pilot jamming (Jamming of Cell Specific Reference Signal) in the LTE downlink. Our results show that full-band jamming of pilots needs 5 dB less power than jamming the entire downlink signal, in order to cause Denial of Service (DoS) to the users. In addition to this, we have identified and demonstrated a previously unreported issue with LTE termed ‘Channel Quality Indicator (CQI) Spoofing’. In this scenario, the attacker tricks the user terminal into thinking that the channel quality is good, by transmitting interference transmission only on the data locations, while deliberately avoiding the pilots. This jamming strategy leverages the dependence of the adaptive modulation and coding (AMC) schemes on the CQI estimate in LTE. Lastly, we investigate the idea of pilot pattern adaptation for SISO- and spatial multiplexing MIMO-OFDM systems. We present a generic heuristic algorithm to predict the optimal pilot spacing and power in a nonstationary doubly selective channel (channel fading in both time and frequency). The algorithm fits estimated channel statistics to stored codebook channel profiles and uses it to maximize the upper bound on the constrained capacity. We demonstrate up to a 30% improvement in ergodic capacity using our algorithm and describe ways to minimize feedback requirements while adapting pilot patterns in multi-band carrier aggregation systems. We conclude this work by identifying scenarios where pilot adaptation can be implemented in current wireless networks and provide some guidelines to adapt pilots for 5G. / Master of Science

Earthquakes pose a significant threat as one of the most destructive natural disasters globally. Despite ongoing efforts to predict earthquakes, the success of such research remains a challenge, necessitating interdisciplinary research and collaboration. The EU-funded Project artEmis seeks to address this challenge in earthquake-prone regions of Europe by establishing a multi-sensor Internet of Things (IoT) network to monitor radon gas concentration in groundwater near fault lines. This thesis focuses on supporting the project by developing the software interface for the transmission of data from a gateway controller to the cloud interface, addressing key functionalities. The goal is to establish two-way communication between the gateway controller and the cloud using the MQTT-SN protocol. Additionally, other functionalities such as data storage and sensor data anomaly detection are also explored and implemented. This research employs an applied research approach, consisting of literature reviews, development, and evaluation phases. The development phase consists of the design and implementation of memory storage, data generation, and bi-directional communication features which align with the project goals. The evaluation of the software development process is achieved through a comprehensive set of functional and end-to-end tests. These tests examine the intricacies of the different software components, with rigorous evaluation against all test criteria and project requirements. The evaluation process concluded with a favourable outcome, indicating that all tests were successful. Additionally, a detailed evaluation of memory capacity was conducted to understand the system’s data retention capability, alongside an analysis of throughput and latency. The memory evaluation demonstrated efficient allocation within the processor’s memory, offering 2.7 days of data storage with specific intervals. Throughput analysis revealed a positive correlation between larger data packets and increased transfer rates, and latency increased with larger packets, possibly due to network congestion and processing delays. However, it is important to acknowledge several inherent limitations in this work, including constrained bi-directional communication capabilities, the absence of a serial interface with sensors, limitations in report size, and constraints on storage capacity. These factors serve as essential contextual considerations for the scope and capabilities of our project. In summary, this research supports Project artEmis by developing a vital software interface for the IoT network. Successful evaluation of the software through comprehensive testing signifies a significant step forward in earthquake monitoring. Despite certain limitations, this work contributes to enhancing our understanding and response to seismic threats. / Jordbävningar utgör ett betydande hot som en av de mest förödande naturliga katastroferna globalt sett. Trots pågående ansträngningar att förutsäga jordbävningar förblir framgången för sådan forskning en utmaning, vilket kräver tvärvetenskaplig forskning och samarbete. Det EU-finansierade projektet artEmis syftar till att belysa detta problem i jordbävningsbenägna regioner i Europa genom att etablera ett multisensor Internet of Things (IoT)-nätverk för att övervaka radongaskoncentrationen i grundvatten nära förkastningslinjer. Denna uppsats fokuserar på att stödja projektet genom att utveckla programvarugränssnittet för överföring av data från en gateway-controller till molngränssnittet samt upplyser viktiga funktioner. Målet är att etablera tvåvägskommunikation mellan gateway-controllern och molnet med hjälp av MQTT-SN-protokollet. Dessutom utforskas och implementeras även andra funktioner, såsom datalagring och detektering av avvikelser i sensordata. Denna forskning använder en tillämpad forskningsmetod som består av litteraturstudier, utveckling och utvärderingsfaser. Utvecklingsfasen innefattar design och implementering av funktioner för minneslagring, datagenerering och tvåvägskommunikation som överensstämmer med projektets mål. Utvärderingen av programvaruutvecklingsprocessen uppnås genom omfattande funktionella och slutanvändartester. Dessa tester granskar de olika programvarukomponenternas komplexiteter och utvärderas noggrant mot alla testkriterier och projektets krav. Utvärderingsprocessen avslutades med ett gynnsamt resultat, vilket indikerar att alla tester var framgångsrika. Dessutom gjordes en detaljerad utvärdering av minneskapaciteten för att förstå systemets datalagringsförmåga, tillsammans med en analys av genomströmning och latens. Minnesutvärderingen visade på effektiv allokering i processorns minne och erbjöd 2,7 dagars datalagring med specifika intervall. Genomströmningsanalys avslöjade en positiv korrelation mellan större datapaket och ökade överföringshastigheter, och latensen ökade med större paket, möjligen på grund av nätverksstockning och bearbetningsförseningar. Det är dock viktigt att erkänna att det finns flera begränsningar i forskningen, inklusive begränsade tvåvägskommunikationsmöjligheter, begränsningar i rapportstorlek och lagringskapacitet, och ett saknande av seriellt gränssnitt med sensorer. Dessa faktorer är viktiga för förståelsen av omfattningen och förmågorna hos vårt projekt. Sammanfattningsvis stöder denna forskning Project artEmis genom att utveckla en avgörande programvarugränssnitt för IoT-nätverket. Den framgångsrika utvärderingen av programvaran genom omfattande tester har lett till ett betydande steg framåt inom jordbävningsövervakning. Trots vissa begränsningar bidrar detta arbete till att förbättra vår förståelse och förmåga att reagera på seismiska händelser.

Long Term Evolution (LTE) is fourth generation broadband wireless access technology. As LTE networks continue to expand, their energy consumption has become a concern due to increased costs and environmental impact. To address this issue, we present a novel approach in this thesis that focuses on energy-efficient LTE network operation by optimizing cell bandwidth deployment. Only historical data extracted from a real-world LTE network is provided by Ericsson in the thesis, so the model has to learn the pattern by exploiting the data. The model formulates the task as an offline contextual bandits problem and implements offline learning and evaluation algorithms. In addition, the model incorporates two agents: an energy-driven agent and a teacher agent within the bandwidth recommendation engine. This enables energy savings while ensuring uninterrupted network service. Users have the flexibility to customize the desired percentage of energy savings by adjusting a hyper-parameter that determines the relative weight of the two agents in the final bandwidth decision. Through comprehensive offline evaluation, the model is assessed and demonstrates its ability to conserve energy without compromising network performance. / Long Term Evolution (LTE) är en fjärde generationens bredbandslösning för trådlös access. Medan LTE-nätverk fortsätter att expandera har energiförbrukningen blivit en oro på grund av ökade kostnader och miljöpåverkan. För att hantera denna fråga presenterar vi i denna avhandling en innovativ metod som fokuserar på energieffektiv drift av LTE-nätverk genom att optimera tilldelningen av cellbandbredd. Endast historiska data som utvunnits från ett verkligt LTE-nätverk tillhandahålls av Ericsson i avhandlingen, vilket innebär att modellen måste lära sig mönster genom att utnyttja dessa data. Modellen formulerar uppgiften som ett offline-contextual bandits-problem och implementerar algoritmer för offline-inlärning och utvärdering. Dessutom inkluderar modellen två agenter: en energistyrd agent och en läraragent i bandbreddrekommendationssystemet. Detta möjliggör energibesparingar samtidigt som kontinuerlig nätverkstjänst garanteras. Användare har flexibiliteten att anpassa den önskade procentandelen av energibesparingar genom att justera en hyperparameter som bestämmer den relativa vikten av de två agenterna vid beslutsfattandet om slutlig bandbredd. Genom omfattande utvärdering offline bedöms modellen och dess förmåga att spara energi utan att äventyra nätverksprestanda bekräftas.

The division of computer engineering at Linköping’s university is currentlydeveloping an innovative parallel DSP processor architecture called ePUMA. Onepossible future purpose of the ePUMA that has been thought of is to implement itin base stations for mobile communication. In order to investigate the performanceand potential of the ePUMA as a processing unit in base stations, a model of theLTE physical layer uplink receiving chain has been simulated in Matlab and thenpartially mapped onto the ePUMA processor.The project work included research and understanding of the LTE standard andsimulating the uplink processing chain in Matlab for a transmission bandwidth of5 MHz. Major tasks of the DSP implementation included the development of a300-point FFT algorithm and a channel equalization algorithm for the SIMD unitsof the ePUMA platform. This thesis provides the reader with an introduction tothe LTE standard as well as an introduction to the ePUMA processor. Furthermore,it can serve as a guidance to develop mixed point radix FFTs in general orthe 300 point FFT in specific and can help with a basic understanding of channelequalization. The work of the thesis included the whole developing chain from understandingthe algorithms, simplifying and mapping them onto a DSP platform,and testing and verification of the results.

This thesis proposes four novel techniques to solve the problem of growing energy consumption requirements in cellular communication networks. The first and second part of this work propose a novel energy efficient scheduling mechanism and two new bandwidth management techniques, while the third part provides an algorithm to actively manage the power state of base stations (BSs) so that energy consumption is minimized throughout the day while users suffer a minimal loss in achieved data rate performance within the system. The proposed energy efficient score based scheduler (EESBS) is based on the already existing principle of score based resource allocation. Resource blocks (RBs) are given scores based on their energy efficiency for every user and then their allocation is decided based on a comparison between the scores of the different users on each RB. Two additional techniques are introduced that allow the scheduler to manage the user’s bandwidth footprint or in other words the number of RBs allocated. The first one, bandwidth expansion mode (BEM), allows users to expand their bandwidth footprint while retaining their overall transmission data rate. This allows the system to save energy due to the fact that data rate scales linearly with bandwidth and only logarithmically with transmission power. The second technique, time compression mode (TCoM), is targeted at users whose energy consumption is dominated by signalling overhead transmissions. If the assumption is made that the overhead is proportional to the number of RBs allocated, then users who find themselves having low data rate demands can release some of their allocated RBs by using a higher order modulation on the remaining ones and thus reduce their overall energy expenditure. Moreover, a system that combines all of the aforementioned scheduling techniques is also discussed. Both theoretical and simulation results on the performance of the described systems are provided. The energy efficient hardware state control (EESC) algorithm works by first collecting statistical information about the loading of each BS during the day that is due to the particular mobility patterns of users. It then uses that information to allow the BSs to turn off for parts of the day when the expected load is low and they can offload their current users to nearby cell sites. Simplified theoretical, along with complete system computer simulation, results are included. All the algorithms presented are very straightforward to implement and are not computationally intensive. They provide significant energy consumption reductions at none to minimal cost in terms of experienced user data rate.