The paper details the usage of mmWave radars to track people and monitor their movement through predefined zones of interest. The theoretical part describes the physical nature of the technology and then describes algorithms which can be used to monitor using it to monitor the movement of people. In the practical part, I have developed a concrete algorithm which can be used to monitor customer queues and cash registers in shops and inform the cashiers when their presence is needed, as well as gather impersonal GDPR-compliant data about the customer's habits. Afterwards, I have developed a visualization for the Windows platform, which can be used to communicate with the radar, manage its configuration, visualize the events in real time and perform further analysis of the measured data.

The availability of feedback from the receiver to the transmitter in a communication system can play a significant role. In this dissertation, our focus is specifically on binary or one-bit feedback. First, we study the problem of successive beam alignment for millimeter-wave channels where the receiver sends back only one-bit of information per beam sounding. The sparse nature of the channel allows us to interpret channel sounding as a form of questioning. By posing the alignment problem as a questioning strategy, we describe adaptive (closed-loop) and non-adaptive (open-loop) channel sounding techniques which are robust to erroneous feedback signals caused by noisy quantization. In the second part, we tightly characterize the capacity for two binary stochastic-adversarial mixed noise channels. Specifically, the transmitter (Alice) intends to convey a message to the receiver (Bob) over a binary symmetric channel (BSC) or a binary erasure channel (BEC) in the presence of an adversary (Calvin) who injects additional noise at the channel's input subject to a budget constraint. Calvin is online or causal in that at any point during the transmission, he can infer the bits being sent by Alice and those being received by Bob via a feedback link. Finally in the third part, we study the applicability of binary feedback for encoding and propose the framework of linearly adapting block feedback codes. We also prove a new result for Reed-Muller (RM) codes to demonstrate how an uncoded system can mimic a RM code under this framework, against remarkably large feedback delays.

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Future 6G wireless communications network will increase the data capacity to unprecedented numbers and thus empower the deployment of new real-time applications. Millimeter-Wave (mmWave) band and Massive MIMO are considered as two of the main pillars of 6G to handle the gigantic influx in data traffic and number of mobile users and IoT devices. The small wavelengths at these frequencies mean that more antenna elements can be placed in the same area. Thereby, high spatial processing gains are achievable that can theoretically compensate for the higher isotropic path loss. The propagation characteristics at mmWave band, create sparse channels in typical scenarios, where only few paths convey significant power. Considering this feature, Hybrid (analog-digital) Beamforming introduces a new signal processing framework which enables energy and cost-efficient implementation of massive MIMO with innovative smart arrays. In this setup, the analog beamalignment via beam selection in link access phase, is the critical performance limiting step. Considering the variable operating condition in mmWave channels, a desirable solution should have the following features: efficiency in training (limited coherence time, delay constraints), adaptivity to channel conditions (large SNR range) and robustness to realized channels (LOS, NLOS, Multipath, non-ideal beam patterns). For the link access task, we present a new energy-detection framework based on variable length channel measurements with (orthogonal) beam codebooks. The proposed beam selection technique denoted as composite M-ary Sequential Competition Test (SCT) solves the beam selection problem when knowledge about the SNR operating point is not available. It adaptively changes the test length when the SNR varies to achieve an essentially constant performance level. In addition, it is robust to non-ideal beam patterns and different types of the realized channel. Compared to the conventional fixed length energy-detection techniques, the SCT can increase the training efficiency up to two times while reducing the delay if the channel condition is good. Having the flexibility to allocate resources for channel measurements through different beams adaptively in time, we improve the SCT to eliminate unpromising beams from the remaining candidate set as soon as possible. In this way, the Sequential Competition and Elimination Test (SCET) significantly further reduces training time by increasing the efficiency. The developed ideas can be applied with different codebook types considered for practical applications. The reliable performance of the beam selection technique is evident through experimental evaluation done using the state-of-the-art test-bed developed at the Vodafone Chair that combines a Universal Software Radio Peripheral (USRP) based platform with mmWave frontends.

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No description available.

No description available.

With the emergence of Fifth Generation (5G) mobile networks, the employment ofhigher frequencies in the millimeter-wave (mmWave) range and the realization of agreat number of beams in 5G radio base stations (RBS) make the electromagnetic (EM)simulation of RBS products very costly in terms of hardware and time requirements.In order to compute the electromagnetic field (EMF) exposure in close proximity of theRBS, more efficient simulation methods are required.The move to mmWave frequencies enables the use of the so-called high frequencymethods for EM simulation with RBS antennas. In this thesis, conventional fullwavesimulation solvers and different implementations of hybridization of highfrequency methods with conventional methods are used with different commercial EMsimulation tools, and their performance is evaluated for the purpose of EMF exposureassessment in close proximity of 5G mmWave RBS.Among all the investigated methods, the hybrid scheme with Finite IntegrationTechnique (FIT) and Shooting and Bouncing Rays (SBR) methods, e.g., thatimplemented in CST Studio Suite 2020, outperforms in terms of hardwarerequirements and time costs, although the accuracy is compromised on the side andbehind the mmWave RBS. The Multilevel Fast Multipole Method (MLFMM), e.g.,that implemented in Altair FEKO 2019, though not a hybrid method, also has goodperformance but requires very large Random Access Memory (RAM), and it cannothandle very exquisite details of RBS. The Finite Difference Time Domain (FDTD)method implemented in EMPIRE XPU can also handle the investigated problemseffciently, but for extremely large problems, its requirements on RAM may become thebottleneck. In the thesis, many other hybrid implementations are also investigated,but it is found that they are not suitable for the EMF exposure assessment in closeproximity of the mmWave RBS with evaluation on a planar area of 0.42 m × 1 m at 28 GHz due to various reasons. / För den femte generationens (5G) mobilnät kommer användningen av millimetervågoroch det stora antalet lober som en radiobasstation (RBS) kan hantera att betydaett kraftigt ökat behov av hårdvara och större tidsåtgång för att göra beräkningarav exponeringen för elektromagnetiska fält nära utrustningen. Därför behövs mereffektiva simuleringsmetoder.Eftersom systemen opererar på millimetervåg-frekvenser kan högfrekvensmetoderanvändas i simuleringen av simuleringen av en RBS. I den här avhandlingenutvärderas konventionella metoder, samt olika hybridmetoder för beräkningenav EMF-exponeringen av millimetervågor i närheten av en RBS. De utvärderadehybridmetoderna är implementerade i olika mjukvaror och blandar användandet avhögfrekvensmetoder och konventionella metoder.Av alla utvärderade metoder fungerar hybridmetoden implementerad med finitaintegralmetoden (FIT) och ”Shooting and Bouncing Rays”-metoden (SBR) i CST bästi termer av vilken hårdvara som behövs för beräkningarna och för tidsåtgången.Dock är noggrannheten i beräkningarna på sidan av och bakom RBSen mindrebra. Multilevel Fast Multipole Method (MLFMM)”-lösaren i Feko i FEKO använderingen hybridmetod men presterar bra, men den kräver mycket RAM-minne och kaninte ta hänsyn till små detaljer i RBSen. Finita differensmetoden i tidsdomänen(FDTD) i EMPIRE kan också användas men dess RAM-krav blir en flaskhals förstora simuleringar. Ytterligare hybridmetoder är undersökta i avhandlingen men medslutsatsen att de inte är användbara (av olika anledningar) för beräkningen av EMFexponeringenfrån en RBS opererandes på frekvensen 28 GHz och över en yta som är0.42 x 1 m.

This research focuses on radio wave propagation at millimeter-wave frequencies. A measurement based channel characterization approach is taken in the investigation. First, measurement techniques are analyzed. Three types of measurement systems are designed, and implemented in measurement campaigns: a narrowband measurement system, a wideband measurement system based on Vector Network Analyzer, and sliding correlator systems at 5.8+AH4AXA-mbox{GHz}, 38+AH4AXA-mbox{GHz} and 60+AH4AXA-mbox{GHz}. The performances of these measurement systems are carefully compared both analytically and experimentally. Next, radio wave propagation research is performed at 38+AH4AXA-mbox{GHz} for Local Multipoint Distribution Services (LMDS). Wideband measurements are taken on three cross-campus links at Virginia Tech. The goal is to determine weather effects on the wideband channel properties. The measurement results include multipath dispersion, short-term variation and signal attenuation under different weather conditions. A design technique is developed to estimate multipath characteristics based on antenna patterns and site-specific information. Finally, indoor propagation channels at 60+AH4AXA-mbox{GHz} are studied for Next Generation Internet (NGI) applications. The research mainly focuses on the characterization of space-time channel structure. Multipath components are resolved both in time of arrival (TOA) and angle of arrival (AOA). Results show an excellent correlation between the propagation environments and the channel multipath structure. The measurement results and models provide not only guidelines for wireless system design and installation, but also great insights in millimeter-wave propagation. / Ph. D.