In the last decade we have experienced a rapid increase in the demand for high data rates over cellular networks. This increase has been partly satisfied by the introduction of multi-user multiple-input multiple-output (MU-MIMO). In such systems, the base station (BS) is equipped with multiple antennas and the users share the time-frequency resources. However, modern communication systems are highly power inefficient. Further, the increase in demand for higher data rates is expected to accelerate in the years to come due to the popularity of mobile devices like smartphones and tablets. Hence, next generation cellular systems arerequired to exhibit high energy efficiency as well as low power  consumption. Recently, it has been shown that the deployment of a large excess of base station (BS) antennas in comparison to the served users can be a promising candidate to meet these contradictory requirements. These systems are termed as Massive MIMO. When the number of BS antennas grows large, the channels between different users become orthogonal and low complexity transceiver processing exhibits sum-rate performance that is close to optimal. In order to realize the promised gains of Massive MIMO systems, it is required that power efficient and inexpensive components are used. In contemporary cellular systems, multi-carrier transmission is used since it facilitates simple equalization at the receiver side. However, multi-carrier signals exhibit high peak-to-average-power-ratio (PAPR) and require expensive highly linear power amplifiers. Power amplifiers in this regime are also very power inefficient. On the other hand single carrier signals exhibit lower PAPR and are suitable for signal design that is more robust to non-linear power amplifiers. Further, single-carrier signals are less vulnerable to hardware impairments, such as phase noise. In this thesis we study the fundamental limits of Massive MIMO systems in terms of sum-rate performance with single-carrier transmission and phase noise and provide important insight on the design of Massive MIMO under these scenarios.

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Given synchronized video sequences from a number of cameras withoverlapping fields of view, the detection and tracking of a prioriunknownnumber of individuals entering a determined area is considered,showingthat a generative model can accurately follow the individuals and handleeffectively such problems as occlusions in each view independently. Theaim of this thesis is to implement the exchange of information betweenthe cameras where the detection and tracking processes take place. Theinputs are obtained from synchronized videos and the frames are takenindividually to treat them as independent images. The proposed algo-rithm was implemented in MATLAB and results obtained on a personalcomputer are presented. The results show that the algorithm achievesgood tracking accuracy, has relatively low computational complexity, andat the same time it allows to observe the communication requirementsbetween the cameras and the processing node.

QC 20120119

I detta examensarbete undersöks hur nya byggmaterial dämpar radiosignaler samt vilken miljöpåverkan eventuella signalförbättrande lösningar kan ha. Miljömedvetenhet och hållbara tekniska lösningar är måsten då planering av nya byggnader görs. Detta sätter stor press på byggföretagen som har stora krav på sig att tänka energieffektivitet och långsiktighet. Nya material och byggtekniker syftar till att reducera den mängd energi som krävs för uppvärmning av bostäder. En konsekvens av detta är att radiosignalerna dämpas och att de boende inte har en fullgod mottagning på sina mobiltelefoner inomhus. För att komma runt mottagningsproblematiken öppnas ett fönster alternativt balkongdörren för att få acceptabel mottagning. De energiförluster som uppstår på grund av vädring är en viktig parameter att ta i beaktande. En minskning skulle kunna vara ett incitament för en fastighetsägare att vilja satsa på mottagningsförbättrande åtgärder. För att bättre få en förståelse för problemen gjordes mätningar på nybyggda hus som ansågs representativa. Resultaten av mätningarna användes senare i matematiska modeller för att analysera och för att skapa förståelse för problemet. Resultatet visar tydlig att den gamla schablonen för förlust på 15 dB inte funkar på nya energieffektiva fastigheter. I rapporten förslås därför ett nytt värde på 23 dB som analysen av det insamlade datat visar. Yttäckningsmodeller gjorda med det nya värdet visat på en minskning av täckningsområdet från basstationen. / The goal of this thesis is to examine the attenuation of new building materials on radio signals and the environmental effects that any signal improving solution might have. Environmental awareness and sustainable solutions are key issues when planning new buildings. Energy conservation and planning for the future puts pressure on companies to rethink the way they plan and construct new buildings. New materials and new techniques are required to reduce the amount of energy it takes to heat our buildings. One unfortunate drawback is the attenuation these new materials have on radio signals. This creates problems for the tenants as they are no longer able to use their mobile telephones indoors. To get around that problem a windows or door to the balcony is opened to get an acceptable reception. The energy losses that occur as a result are important to consider. A decrease in these energy losses might serve as an incentive for real estate owners to invest in signal improving solutions for their buildings. To get a better understanding of the problem, tests were performed in buildings that incorporate these new materials and techniques. The results of these tests were then used in mathematical models to analyze and to get a better understand the size of the problem. The results show a significant difference when compared to values used in previous calculations where 15dB was seen as a reasonable. This report suggest that the old value is changed to 23dB as seen in the analysis of the data collected. When this new value is used in the surface coverage models, the decrease in cell coverage from the base station becomes evident.

The emergence of resource-rich mobile devices and smart vehicles has paved the way for Urban Sensing. In this new paradigm, users sense their environment and become part of an unprecedented large-scale network of sensors, with extensive spatial and temporal coverage, that enables the collection and dissemination of real-time information, practically, from anywhere. Urban sensing can facilitate the deployment of innovative applications that can address the ever-growing concerns for citizens’ well-being. Nevertheless, the openness of such systems (ideally anyone can participate) and the richness of the data users contribute unavoidably raise significant concerns for both the security of urban sensing applications and the privacy of the participating users. In this thesis we consider different urban sensing application domains: vehicular communication networks, intelligent transportation systems and environmental monitoring applications. We begin with a detailed analysis of the security and privacy requirements of these applications domains. Our objective is to protect users from the system (by ensuring their anonymity and privacy) and urban sensing systems from malicious users (by holding malicious users accountable of their actions). This is not straight-forward; anonymity may tempt malicious user behavior, compromising the reliability of the entire urban sensing system.Towards that, we design and implement secure and privacy-preserving identity management systems that can accommodate these requirements. We demonstrate their efficiency, practicality, and scalability through extensive experimental evaluations. Furthermore, we formally evaluate formally their security and privacy preserving properties. / <p>QC 20141001</p>

In current wireless communication systems, demands for extremely high data rates, along with spectrum scarcity at the microwave bands, make the millimeter wave (mmWave) band very appealing to provide these extremely high data rates even for a massive number of wireless devices. MmWave communications exhibit severe attenuation, vulnerability to obstacles (called blockage), and sparse-scattering environments. Moreover, mmWave signals have small wavelengths that allow the incorporation of many antenna elements at the current size of radio chips. This leads to high directivity gains both at the transmitter and at the receiver, directional communications, and, more importantly, possible noise-limited operations as opposed to microwave networks that are mostly interference-limited. These fundamental differences between mmWave networks and legacy communication technologies challenge the classical design constraints, objectives, and available degrees of freedom. The natural consequence is the necessity of revisiting most of the medium access control (MAC) layer design principles for mmWave networks, which have so far received less attention in the literature than physical layer and propagation issues. To address this important research gap, this thesis investigates the fundamental MAC layer performance metrics, including coverage, fairness, connection robustness, collision probability, per-link throughput, area spectral efficiency, and delay. The original analysis proposed in this thesis suggests novel insights as to the solutions for many MAC layer issues such as resource allocation, interference management, random access, mobility management, and synchronization in future mmWave networks. A first thread of the thesis focuses on the fundamental performance analysis and mathematical abstraction of mmWave wireless networks to characterize their differences from conventional wireless networks, i.e., high directivity, line-of-sight communications, and occurrence of deafness (misalignment between transmitters and receivers). A mathematical framework to investigate the impact of beam training (alignment) overhead on the throughput is established, which leads to identify a new alignment-throughput tradeoff in mmWave networks. A novel blockage model that captures the angular correlation of line-of-sight conditions using a new notion of "coherence angle" is proposed. The coverage and delay of directional cell discovery are evaluated, and an optimization approach to maximize long-term throughput of users with fairness guarantees is proposed. In addition, this thesis develops a tractable approach to derive the collision probability, as a function of density of the transmitters, transmission power, density and size of the obstacles, operating beamwidth, and sensitivity of the receiver, among the main parameters. The collision probability allows deriving closed-form expressions for the per-link and network throughput of mmWave networks, and thereby identifying that, contrary to mainstream belief, these networks may exhibit a non-negligible transitional behavior of interference from a noise-limited to an interference-limited regime. The second thread of the thesis builds on the previous fundamental performance analysis and modeling to establish new, efficient MAC protocols. The derived collision probability is used to evaluate per-link throughput, area spectral efficiency, and delay performance of common MAC protocols such as TDMA and slotted ALOHA, and to provide a fundamental comparison between pros and cons of contention-free and contention-based MAC protocols. The results suggest the use of on-demand interference management strategy for future mmWave cellular networks and collision-aware hybrid MAC protocols for mmWave ad hoc networks to reliably deliver messages without sacrificing throughput and delay performance. Moreover, the transitional behavior, together with significant mismatch between transmission rates of control and data messages, imposes the development of new hybrid proactive and reactive control plane architecture. This thesis identifies the prolonged backoff time problem, which happens in mmWave networks due to blockage and deafness, and proposes a new collision notification signal to solve this problem. Motivated by the significant mismatch between coverage of the control and data planes along with delay analysis of directional cell search, a novel two-step synchronization procedure is proposed for mmWave cellular networks. Also, the impact of relaying and multi-hop communication to provide reliable mmWave connections, to alleviate frequent handovers, and to reduce the beam training overhead is investigated. The investigations of this thesis aim to demystify MAC layer performance of mmWave networks and to show the availability of many new degrees of freedom to improve the network performance, e.g., in terms of area spectral efficiency, energy efficiency, robustness, delay, coverage, and uniform quality of service provisioning. The results reveal many special behaviors of mmWave networks that are largely ignored in design approach of the current mmWave networks. Given that the standardization of mmWave wireless cellular networks has not started as yet, and that existing standards of mmWave ad hoc networks are highly sub-optimal, the results of this thesis will provide fundamental design guidelines that have the potential to be very useful for future mmWave standardizations. / <p>QC 20150907</p>

Web Call Example Application from Ericsson Developer Connection is an application that hosted at a web server and supplies functionality of VoIP phone calls. Users can access the service from desktop browser, mobile phone browser or Java ME Client. Users can also manage their contact books. Each user can have more than one VoIP service accounts, so they can choose the cheapest on when they make phone call. The Web Call Example Application supports two kinds of VoIP phone call connection: Relay Call and Third Party Call. For the Third Party Call there are four different implementations: Call Transfer, SDP Swap, Re-invite and Web Client. This master thesis introduces the theory of third party call and the implementation of Web Call Example Application.

This report is the result of a masters degree project conducted at the Department of Teleinformatics at the Royal Institute of Technology during the autumn 1995. The area investigated is the Mobile Internet Protocol, especially its implementation and efficiency. The thesis work is divided into three areas. The first area includes the development and implementation of a Management Information Base for the Mobile-IP protocol. The second area deals with the porting of a Mobile-IP implementation for SunOS to MachOS and Solaris. The last area covers the tests done to measure the throughput and latency of the protocol.