La nécessité d'une transmission sans fils des données à des débits élevés, à la fois fiables et avec de faible latence a donné lieu à ces dernières années à une succession de normes sans fil, allant de 3G-4G, WLAN à la cinquième génération (5G) des réseaux mobiles. Dans ce contexte, les équipementiers, ainsi que les opérateurs, doivent élaborer des méthodes d'essai standard précises et efficaces pour évaluer les performances des systèmes et des terminaux. Les méthodologies de test en direct par voie aérienne ("Over-The-Air") (OTA) visent à reproduire des environnements multi-trajets radio en laboratoire de manière répétable et contrôlable, en évitant les coûteuses mesures in-situ. L'objectif de cette thèse est de proposer une nouvelle méthodologie d'essai OTA, afin de reproduire la propagation des canaux radio, sur une large bande et d'évaluer les performances des systèmes sans fil dans des environnements réels. La thèse débute en présentant les bases de la chaîne radio et de certains modèles de chaînes présentés dans la littérature. Ensuite, un examen critique des méthodologies OTA existantes dans la littérature est fourni. Parmi les différentes méthodologies, nous avons opté pour l'approche de la chambre anéchoïde multi-sonde, qui consiste à déployer un certain nombre de sondes autour d'un équipement radio sous test et à les alimenter avec un émulateur d’évanouissements (fading). Cette méthodologie fournit une reproduction précise des caractéristiques des canaux spatiaux, qui sont nécessaires pour évaluer la performance des terminaux multi-antennes dans des environnements réels. L'avantage le plus important de cette méthodologie est la capacité d'imiter différents modèles de canaux en termes de résolution spatiale, d’évanouissements angulaire et temporel. Un outil de simulation a été développé pour étudier et déterminer les caractéristiques de l'installation OTA pour différents types de canaux d’intérêt. En particulier, le nombre et la mise en place des antennes nécessaires et la taille de l'installation ont été étudiés en fonction de la taille électrique du dispositif testé. Sur la base des études de dimensionnement, une configuration OTA expérimentale a été réalisée pour reproduire les caractéristiques des canaux dans l'espace tridimensionnel pour une plage de fréquences de 2 à 6 GHz. / The need for high data-rate, reliable and low latency transmission in wireless communication systems motivated a multitude of wireless standards, spanning from 3G-4G, WLAN to the upcoming fifth generation (5G) of mobile networks. In this context, technology providers, as well as operators, need to develop accurate and cost effective standard test methods, to evaluate devices performance. Over-The-Air (OTA) test methodologies aim to reproduce radio multipath environments in laboratory in repeatable and controllable manner, avoiding costly field test. The focus of this thesis is to propose a new OTA test methodology, in order to emulate radio channel propagation, over a wide band, and to evaluate the performance of the wireless systems in real environments. We start our study by introducing the basics of radio channel and some channel models presented in literature. Then a critical review of existing OTA methodologies in literature is provided. Among the different methodologies we opted for the multi-probe anechoic chamber approach, which consists into deploying a number of probes around a device, and feed them with fading emulator. This methodology provides an accurate reproduction of spatial channel characteristics, which are needed to assess the performance of multi-antenna terminals in real environments. The most important advantage of this methodology is the capability to emulate different channel model in term of spatial resolution, angular and temporal fading. A simulation tool was developed to investigate and determine the OTA setup under different channel condition. In particular the number and emplacement of antennas needed and the size of the setup were investigated as a function of the electrical size of the device under test. Based on the dimensioning studies, an experimental OTA setup was realized to reproduce the channel characteristics in the three dimensional space for a frequency range from 2 to 6 GHz.

Multiple-input multiple-output (MIMO) technology has enabled increased performance of wireless communication devices. The increased complexity associated with MIMO devices requires more realistic testing environments to ensure device performance. This testing can be accomplished by either very accurate but expensive anechoic chambers, less accurate but inexpensive mode-stirred chambers, or the newly introduced reconfigurable over-the-air chamber (ROTAC) that combines the benefits of both anechoic chambers and reverberation chambers. This work focuses on efficient optimization methods to quantify the performance of the ROTAC. First, an efficient optimization technique that combines convex optimization and a simple gradient descent algorithm is developed that can be applied to different ROTAC performance metrics. Plane wave synthesis is used to benchmark performance versus chamber complexity, where the complexity is defined in terms of chamber size and the number of ports in the chamber. Next, the optimization technique is used to study the spatial channel characteristics (power angular spectrum) of the chamber and the generation of arbitrary fading statistics inside the chamber. Lastly, simulation results are compared with practical hardware measurements to highlight the accuracy of the simulation model for the chamber. Overall, this work provides a comprehensive analysis for optimization of different ROTAC performance metrics.

Abstract This thesis discusses radio channel modelling for evolving radio access and of using the models in practice in a setup for radiated testing of radio devices. New telecommunication systems are constantly being developed to address continuously increasing wireless communication needs. The first pieces of intensively developed fifth generation (5G) networks and devices are planned to be available, in some form, approximately by 2020. An interesting feature of 5G concerning propagation and consequently channel modelling, is the expected utilization of frequencies clearly higher than the legacy cellular systems. This work aims to define a channel model for the simulated evaluation of the coming 5G systems. New requirements for the channel model are identified and addressed. Further, over the air (OTA) testing of 5G devices in fading conditions is examined and a new setup is proposed. The test environment aims to reconstruct a time variant electromagnetic (EM) field around a device under test (DUT) considering the spatial, polarimetric, Doppler, and delay dispersion characteristics specified by the target channel model. Components and key design parameters of the setup are designated. It was found that the proposed map-based channel model is capable of fulfilling the identified requirements. Furthermore, the simulations indicate that the state-of-the-art geometry-based stochastic channel model (GSCM) may give over-optimistic multi-user MIMO (MU-MIMO) performance in an urban micro-cellular environment. The sectored OTA concept was shown appropriate for device testing. Key parameters, such as the physical dimensions of the multi-probe anechoic chamber (MPAC) OTA configuration and the number of active probes, were determined by simulations. The 3GPP is the main forum working towards 5G standards. A channel model for 5G evaluations has recently (2016) been specified. The base-line model is a GSCM inherited from the 4G models. However, the author expects that the proposed map-based models will gain popularity in the future, despite the current widespread use of GSCMs. In the 3GPP working group RAN4 (Radio performance and protocol aspects) the test methods for 5G user equipment (UE) are currently (2017) under investigation. The proposed sectored MPAC method has been contributed to and is under consideration in 3GPP. Even if it is not approved for UE testing, the author expects it to be useful for performance testing of base stations (BSs). / Tiivistelmä Tämän väitöskirjan sisältönä on radiokanavamallinnus langattomia tiedonsiirtojärjestelmiä varten ja lisäksi mallien käyttöönottoa tulevien radiolaitteiden säteilevässä testauksessa. Uusia tietoliikennejärjestelmiä kehitetään jatkuvasti, yhtä lailla jatkuvasti kasvavien tiedonsiirtotarpeiden tyydyttämiseksi. Ensimmäisten verkkojen ja päätelaitteiden pitäisi olla saatavilla tulevaan viidennen sukupolven (5G) järjestelmään vuoden 2020 tietämillä. Työn tarkoituksena on määritellä kanavamalli 5G-järjestelmän simulointeja varten ja sitä edeltäen tunnistaa kanavamallin vaatimukset. Lisäksi tutkimuksen aiheena on 5G-laitteiden säteilevä (OTA) testaus häipyvässä radiokanavassa ja uuden testijärjestelmän määrittely tätä tarkoitusta varten. Ehdotetun testijärjestelmän keskeisenä toimintona on halutun sähkömagneettisen (EM) kentän tuottaminen testattavan laitteen ympärille. EM-kentän pitää olla kanavamallin mukainen ja toteuttaa sen häipymä-, tila-, polarisaatio-, doppler- ja viiveominaisuudet. Testijärjestelmän komponentit ja tärkeimmän suunnitteluparametrit pyritään selvittämään tässä työssä. Tutkimuksessa havaittiin, että ehdotettu karttapohjainen kanavamalli toteuttaa 5G-mallille asetetut vaatimukset. Simuloinnit osoittavat myös, että tyypillisessä kaupunkiympäristössä suosittu GSCM-malli yliarvioi kanavan kapasiteetin monen käyttäjän MIMO-tekniikka käytettäessä. Lisäksi osoitettiin sektoroidun OTA-järjestelmän, jossa hyödynnetään useita antenneja, radiokanavaemulaattoria sekä radiokaiutonta huonetta (MPAC), käyttökelpoisuus 5G-laitteiden testaukseen. Kyseisen testausjärjestelmän parametrit määriteltiin. 3GPP on tärkein foorumi, jolla 5G-standardeja luodaan. Siellä on hiljattain (2016) sovittu 5G-simulointeja varten kanavamalli, joka ei ole tässä työssä ehdotetun kaltainen. Standardoitu malli on tyypiltään GSCM ja se on johdettu suoraan edellisen sukupolven (4G) kanavamallista. Kirjoittaja olettaa tästä GSCM:n nykyisestä vahvasta asemasta huolimatta, että ehdotettu karttapohjainen kanavamalli lisää suosiotaan tulevaisuudessa. Parhaillaan (2017) on 3GPP:n RAN4-työryhmässä käynnissä 5G-päätelaitteiden (UE) testimenetelmien määrittelyvaihe. Väitöskirjassa tutkittua sektoroitua MPAC-menetelmää on ehdotettu työryhmälle standardoitavaksi. Vaikka mainittua menetelmää ei siellä standardoitaisikaan UE-testaukseen, niin voidaan olettaa menetelmän olevan hyödyllinen erityisesti tukiasemien säteilevään testaukseen.

As mobile phones get increasingly complicated the demands for an effective firmware update service increase. A proposed solution is Firmware Over The Air (FOTA) and the Open Mobile Alliance’s Device Management where mobile phones can be updated and managed via the mobile phone network. However, before these operations can be carried out, all FOTA capable mobile phones that should be served must be discovered and registered with a distributor of updates. The information provided must be sufficient to uniquely identify devices, initiate a Device Management session, and determine if a firmware update is needed. This thesis addresses the problems that a solution in automatically collecting this information. Several solutions are presented and their suitability evaluated on the basis of defined and analyzed requirements. The solutions most thoroughly examined are various manual solutions, retrieval of information from core network nodes, and utilizing the Short Message Service (SMS) or Unstructured Supplementary Service Data (USSD). A phone application has been implemented according to the requirements from the Chinese network operator China Mobile Communications Corporation (CMCC). It is a part of a solution in which the information is delivered via a SMS session. The design and development phase of the application is described, accompanied by a brief description of the Symbian OS and the working environment (tools, devices, etc.) needed to implement this solution. This work took place at the Sony Ericsson office in Beijing, China. The application implemented is robust and it is impossible to avoid registration, furthermore the user can not be exposed to acknowledgement messages. It has been made possible on the cost of decreased phone performance (a few kB of memory) since the application runs all the time. Malfunctioning phone or network may hinder registration. / Mobiltelefoner blir ständigt mer komplicerade vilket medför att efterfrågan av en effektiv lösning för uppdateringar av mjukvaran i mobiltelefonerna ökar. Lösningen är Firmware Over The Air (FOTA) och Device Management; mobiltelefonerna uppdateras och sköts via mobiltelefonnätverket. Men innan förfaranden kan exekveras måste alla mobiltelefoner med FOTA som ska omfattas av tjänsten upptäckas och registreras hos den som distribuerar uppdateringarna. Den information som måste levereras måste vara tillräcklig för att kunna identifiera mobiltelefonen, genomföra en Device Management session och avgöra om en uppdatering av mjukvaran är nödvändig. Detta examensarbete behandlar de problem som en lösning i vilken information tillhandahålls möter. Ett flertal lösningar presenteras och deras lämplighet utvärderas på basis av definierade och analyserade krav. De mest ingående undersökta lösningarna är olika manuella lösningar, insamling av information från noderna av kärnnätverket samt utnyttjande av SMS eller USSD. En telefonapplikation har implementeras enligt krav från den kinesiska operatören CMCC. Applikationen är en del av en lösning i vilken informationen levereras via en SMS-session. Applikationens design och utvecklingsfasen är beskriven, samt en översiktlig beskrivning av Symbian operativsystem och utvecklingsmiljön (verktyg, mobiltelefoner, etc.) som behövdes för att implementera lösningen. Detta arbete genomfördes på Sony Ericssons kontor i Beijing, Kina.

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With the emerging Internet of Things (IoT) paradigm, more than a billion sensing devices will be collecting an unprecedented amount of data. Simultaneously, the field of data analytics is being revolutionized by modern machine learning (ML) techniques that enable sophisticated processing of massive datasets. Many researchers are envisioning a combination of these two technologies to support exciting applications such as environmental monitoring, Industry 4.0, and vehicular communications. However, traditional wireless communication protocols are inefficient in supporting distributed ML services, where data and computations are distributed over wireless networks. This motivates the need for new wireless communication methods. One such method, over-the-air computation (AirComp), promises to communicate with massive gains in terms of energy, latency, and spectrum efficiency compared to traditional methods. The expected efficiency of AirComp is due to the complete spectrum sharing for all participating devices. Unlike in traditional physical-layer communications, where interference is avoided by allocating orthogonal communication channels, AirComp promotes interference to compute a function of the individually transmitted messages. However, AirComp can not reconstruct functions perfectly but introduces errors in the process, which harms the convergence rate and region of optimality of ML algorithms. The main objective of this thesis is to develop methods that reduce these errors and analyze their effects on ML performance. In the first part of this thesis, we consider the general problem of designing wireless methods for ML applications. In particular, we present an extensive survey which divides the field into two broad categories, digital communications and analog over-the-air-computation. Digital communications refers to orthogonal communication schemes that are optimized for ML metrics, such as classification accuracy, privacy, and data-importance, rather than traditional communication metrics such as fairness, data rate, and reliability. Analog over-the-air-computation refers to the AirComp method and its application to distributed ML, where communication-efficiency, function estimation, and privacy are key concerns. In the second part of this thesis, we focus on the analog over-the-air computation problem. We consider a network setup with multiple devices and a server that can be reached via a single hop, where the wireless channel is modeled as a multiple-access channel with fading and additive noise. Over such a channel, the AirComp function estimate is associated with two types of error: 1) misalignment errors caused by channel fading and 2) noise-induced errors caused by the additive noise. To mitigate these errors, we propose AirComp with retransmissions and develop the optimal power control scheme for such a system. Furthermore, we use optimization theory to derive bounds on the convergence of an AirComp-supported ML system that reveal a relationship between the number of retransmissions and loss of the ML model. Finally, with numerical results we show that retransmissions can significantly improve ML performance, especially for low-SNR scenarios. / Med Internet of Things (IoT)-paradigmen, kommer över en miljard sensorenheter att samla en mängd data som saknar motstycke. Samtidigt har dataanalys revolutionerats av moderna maskininlärningstekniker (ML) som möjliggör avancerad behandling av massiva dataset. Många forskare föreställer sig en kombination av dessa två two teknologier för att möjliggöra spännande applikationer som miljöövervakning, Industri 4.0, och fordonskommunikation. Tyvärr är traditionella kommunikationsprotokoll ineffektiva när det kommer till att stödja distribuerad maskininlärning, där data och beräkningar är utspridda över trådlösa nätverk. Detta motiverar behovet av nya trådlösa kommunikationsprotokoll. Ett protokoll, over-the-air computation (AirComp), lovar att kommunicera med enorma fördelar när det kommer till energieffektivitet, latens, and spektrumeffektivitet jämfört med traditionella protkoll. AirComps effektivitet beror på den fullständiga spektrumdelningen mellan alla medverkande enheter. Till skillnad från traditionell ortogonal kommunikation, där interferens undviks genom att allokera ortogonala radioresurser, så uppmuntrar AirComp interferens och nyttjar den för att räkna ut en funktion av de kommunicerade meddelanderna. Dock kan inte AirComp rekonstruera funktioner perfekt, utan introducerar fel i processen vilket försämrar konvergensen av ML-algoritmer. Det huvudsakliga målet med den här avhandlingen är att utveckla metoder som minskar dessa fel och att analysera de effekter felen har på prestandan av distribuerade ML-algoritmer. I den första delen av avhandlingen behandlar vi det allmänna problemet med att designa trådlösa nätverksprotokoll för att stödja ML. Specifikt så presenterar vi en utförlig kartläggning som delar upp fältet i två kategorier, digital kommunikation och analog AirComp. Digital kommunikation syftar på ortogonala kommunikationsprotokoll som är optimerade för ML-måttstockar, t.ex. klassifikationskapabilitet, integritet, och data-vikt (data-importance), snarare än traditionella kommunikationsmål såsom jämlikhet, datahastighet, och tillförlitlighet. Analog AirComp syftar till AirComps applicering till distribuerad ML, där kommunikationseffektivitet, funktionsestimering, och integritet är viktiga måttstockar. I den andra delen av avhandlingen fokuserar vi på det analoga AirComp-problemet. Vi beaktar ett nätverk med flera enheter och en server som kan nås via en länk, där den trådlösa kanalen modelleras som en multiple-access kanal (MAC) med fädning och additivt brus. Över en sådan kanal så associeras AirComps funktionsestimat med två sorters fel: 1) felinställningsfel orsakade av fädning och 2) brusinducerade fel orsakade av det additiva bruset. För att mildra felen föreslår vi AirComp med återsändning och utvecklar den optimala "power control"-algoritmen för ett sådant system. Dessutom använder vi optimeringsteori för att härleda begränsningar på konvergensen av ett AirCompsystem för distribuerad ML som tydliggör ett förhållande mellan antalet återsändningar och förlustfunktionen för ML-modellen. Slutligen visar vi att återsändningar kan signifikant förbättra ML-prestanda genom numeriska resultat, särskilt när signal-till-brus ration är låg. / <p>QC 20220909</p>

With increasing amounts of data coming fromconnecting progressively more devices, new machine learningmodels have risen. For wireless networks the idea of using adistributed approach to machine learning has gained increasingpopularity, where all nodes in the network participate in creatinga global machine learning model by training with the localdata stored at each node, an example of this approach is calledfederated learning. However, traditional communication protocolshave been proven inefficient. This opens up opportunities todesign new machine-learning specific communication schemes.The concept ofOver-the-air computationis built on the fact thata wireless communication channel can naturally compute somelinear functions, for instance the sum. If all nodes in a networktransmits simultaneously to a server, the signals are aggregatedbefore reaching the server. / I takt med denökande datamängden frånallt fler uppkopplade enheter har nya modeller för mask-ininlärning dykt upp. För trådlösa nätverk har idén att appliceradecentraliserade maskininlärnings modellerökat i popularitet,där alla noder i nätverket bidrar till en global maskininlärningsmodell genom att träna på den data som finns lokalt på varjenod. Ett exempel på en sådan metodärFederated Learning.Traditionella metoder för kommunikation har visat sig varaineffektiva vilket öppnar upp möjligheten för att designa nyamaskininlärningsspecifika kommunikationsscheman. Konceptetover-the-air computationutnyttjar det faktum att en trådlöskommunikationskanal naturligt kan beräkna vissa funktioner,som exempelvis en summa. Om alla noder i nätverket sändertill en server samtidigt aggregeras signalerna genom interferensinnan de når servern. / Kandidatexjobb i elektroteknik 2020, KTH, Stockholm

no / This paper identifies the need for thorough experimental based study for Software-over-the-air (SOTA) in an automotive context. The paper outlines the challenges and context for automotive SOTA with an extensive literature review. It then details the early stages of the experimental studies, which aim to identify the key control and noise factors that affect performance of the SOTA in an automotive environment. This contribution establishes a framework for uncertainty modelling of SOTA as a system which highlights the needs to develop solutions requiring big data gathering and analysis as next research opportunities to the scientific community. / Jaguar Land-Rover

This thesis discusses the design of two Physical Layer Security (PLS) techniques on Software Defined Radios (SDRs). PLS is a classification of security methods that take advantage of physical properties in the waveform or channel to secure communication. These schemes can be used to directly obfuscate the signal from eavesdroppers, or even generate secret keys for traditional encryption methods. Over the past decade, advancements in Multiple-Input Multiple-Output systems have expanded the potential capabilities of PLS while the development of technologies such as the Internet of Things has provided new applications. As a result, this field has become heavily researched, but is still lacking implementations. The design work in this thesis attempts to alleviate this problem by establishing SDR designs geared towards Over-the-Air experimentation. The first design involves a 2x1 Multiple-Input Single-Output system where the transmitter uses Channel State Information from the intended receiver to inject Artificial Noise (AN) into the receiver's nullspace. The AN is consequently not seen by the intended receiver, however, it will interfere with eavesdroppers experiencing independent channel fading. The second design involves a single-carrier Alamouti coding system with pseudo-random phase shifts applied to each transmit antenna, referred to as Phase-Enciphered Alamouti Coding (PEAC). The intended receiver has knowledge of the pseudo-random sequence and can undo these phase shifts when performing the Alamouti equalization, while an eavesdropper without knowledge of the sequence will be unable to decode the signal. / Master of Science

<p>Nowadays, mobile phones have greater functionality; a camera, color LCD screen, wireless LAN, Bluetooth, IrDA and others. In the near future wider variety of new functionalities will be added, from high quality voice, high definition video to high data rate wireless channels. As consumer electronics integrate greater functionality and high operating frequencies, their emissions will exceed the specified limits, most of these emissions will be a result of the internal interferences in the mobile phone. Moreover higher operating frequencies will be required to improve the quality of these functionalities, something that will make it more difficult to control these interferences. Internal or external sources of electromagnetic interference can degrade the performance of sensitive analog/digital circuits inside the mobile phone. Moreover the electronic device must satisfy a host of global regulations that limit it’s susceptibility to these interferences, as well as the interference emitted by the device itself.</p><p>Therefore designing a new electronic device to perform new and exciting functions will not be a pleasant task if it can not meet certain specifications and function as required to adhere to certain global regulations.</p><p>This thesis project investigates the sources of interference inside a mobile phone; mainly the electromagnetic interferences and its effect on the radio transceiver focusing on the GSM receiver sensitivity. This report is a result of intensive research, an investigation of possible sources of interference, also actual measurements were performed; RSSI, OTA and sniffing measurements; to identify the physical sources of interferences, and their effect on the receiver sensitivity. Finally solutions were recommended and implemented to suppress the interferences due to different sources, mainly through filtering, shielding or proper grounding of signals and components/subsystems in the mobile phone.</p>