Applying frequency scanning arrays for time-efficient analog beam probing in multi-user hybrid beamforming systems

Next generation of mobile communications will have to cover the unceasingly growing demand of higher data rates and reliable services. In this situation it will be a must to migrate towards higher frequencies in the range of millimeter waves (mm-Waves), where there is plenty of available bandwidth, that would allow high data rates. However, for this new range of the spectrum the attenuation suffered is very strong. Therefore, the isotropic antennas used for lower frequencies are going to be replaced for highly directive ones in order to compensate for this effect. But at the same time the use of narrow beam will introduce a new problematic aspect that was previously inexistent, which is beam selection and beam alignment. In order to address this situation, efficient beamforming and beam alignment becomes critical. The ultimate aim of this thesis is to test Frequency Scanning Arrays (FSA) for analog beam probing techniques in multi-user hybrid beamforming systems. In order to achieve it, several previous steps have been made. This thesis is aiming to apply the technology of Frequency Scanning Arrays (FSA) in multiuser hybrid beamforming systems. First the analog beam probing using traditional Exhaustive Search (ES) is implemented, with not only hybrid but also analog and digital schemes. Also, several beam selection algorithms are defined and tested. Afterwards the effect of the channel estimation is considered and a timing delay for each user is implemented, in order to make the final comparison between ES and FSA as realistic as possible. The results obtained show that in most cases analised the FSA system outperforms the ES system. These encouraging results could be a good indicator that the use of FSA analog beam probing has many promising possibilities and has to be further investigated.La próxima generación de comunicaciones móviles tendrá que cubrir la incesantemente creciente demanda de mayores velocidades de transmisión datos y servicios fiables. En esta situación será imprescindible migrar hacia frecuencias más altas en el rango de las ondas milimétricas (mm-Waves), donde hay mucho ancho de banda disponible, que permitiría altas velocidades de transferencia de datos. Sin embargo, para este nuevo rango del espectro la atenuación sufrida es muy fuerte. Por ello, las antenas isotrópicas utilizadas para frecuencias más bajas van a ser sustituidas por otras muy directivas para compensar este efecto. Pero al mismo tiempo, el uso de un haz estrecho introducirá una nueva problemática que antes no existía, que es la selección y la alineación del haz. Para hacer frente a esta situación, una eficiente formación y alineación del haz se convierte en un aspecto fundamental. El objetivo final de esta tesis es probar los Frequency Scanning Arrays (FSA) para las técnicas de sondeo del haz analógico en sistemas de conformación de haz híbrido multiusuario. Para conseguirlo, se han realizado varios pasos previos. En esencia, en esta tesis se propone aplicar la tecnología de los Frequency Scanning Arrays (FSA) en sistemas multiusuario. En primer lugar, se implementa el sondeo analógico del haz mediante la tradicional búsqueda exhaustiva (Exhaustive Search, ES) con esquemas no sólo híbridos sino también analógicos y digitales. Además, se definen y prueban varios algoritmos de selección de haz. Después se considera el efecto de la estimación del canal y se implementa un retardo temporal para cada usuario, con el fin de realizar la comparación final entre ES y FSA de la manera más realista posible. Los resultados obtenidos muestran que en la mayoría de los casos analizados el sistema FSA supera al sistema ES. Estos resultados alentadores podrían ser un buen indicador de que el uso del haz analógico FSA tiene prometedoras posibilidades y tiene que ser investigado más a fondo.La pròxima generació de comunicacions mòbils haurà de cobrir la incessant i creixent demanda d'altes velocitats de transmissió de dades i serveis cada cop més fiables. En aquesta situació serà imprescindible migrar cap a freqüències més altes en el rang de les ones mil·limètriques (mm-Waves), on hi ha un gran ample de banda disponible, que permetria altes velocitats de transferència de dades. Tot i això, per aquest nou rang de l'espectre, l'atenuació que pateix el senyal és molt gran. Per aquesta raó, les antenes isotròpiques utilitzades per a freqüències més baixes seran substituïdes per d'altres molt directives per a compensar aquest efecte. Però al mateix temps, l'ús d'un feix estret introduirà una nova problemàtica que abans no existia, que és la selecció i alineació del feix. Per fer front a aquesta situació, una formació i alineació eficient del feix esdevé un aspecte fonamental. L'objectiu final d'aquesta tesi és provar els Frequency Scanning Arrays (FSA) per a les tècniques de sondeig del feix analògic en sistemes de conformació de feix híbrid multiusuari. Per tal d'aconseguir-ho s'han dut a terme diversos passos previs. En essència, en aquesta tesi es proposa aplicar la tecnologia dels Frequency Scanning Arrays (FSA) en sistemes multiusuari. En primer lloc, s'implementa el sondeig analògic del feix mitjançant la cerca exhaustiva tradicional (Exhaustive Search, ES) amb esquemes no només híbrids sinó també analògics i digitals. A més a més, es defineixen i es proven diversos algoritmes de selecció de feix. Després es considera l'efecte de l'estimació del canal i s'implementa un retard temporal per a cada usuari, amb la finalitat de dur a terme la comparació final entre ES i FSA de la manera més realista possible. Els resultats obtinguts demostren que en la majoria dels casos analitzats el sistema FSA supera al sistema ES. Aquests resultats encoratjadors podrien ser un bon indicador que l'ús del feix analògic FSA ofereix possibilitats prometedores i ha de ser investigat més a fons

Efficient method of estimating Direction of Arrival (DOA) in communications systems.

Masters Degree. University of KwaZulu- Natal, Durban.In wireless communications systems, estimation of Direction of Arrival (DOA) has been used both for military and commercial purposes. The signal whose DOA is being estimated, could be a signal that has been reflected from a moving or stationary object, or a signal that has been generated from unwanted or illegal transmitter. When combined with estimating time of arrival, it is also possible to pinpoint the location of a target in space. Localization in space can also be achieved by estimating DOA using two receiving nodes with capability of estimating DOA. The beamforming pattern in smart antenna system is adjusted to emphasize the desired signal and to minimize the interference signal. Therefore, DOA estimation algorithms are critical for estimating the Angle of Arrival (AOA) and beamforming in smart antennas. This dissertation investigates the performance, angular accuracy and resolution of the Minimum Variance Distortionless Response (MVDR), Multiple Signal Classification (MUSIC) and our proposed method Advanced Multiple Signal Classification (A-MUSIC) as DOA algorithms on both Non-Uniform Array (NLA) and Uniform Linear Array (ULA). DOA is critical in antenna design for emphasizing the desired signal and minimizing interference. The scarcity of radio spectrum has fuelled the migration of communication networks to higher frequencies. This has resulted into radio propagation challenges due to the adverse environmental elements otherwise unexperienced at lower frequencies. In rainfall-impacted environments, DOA estimation is greatly affected by signal attenuation and scattering at the higher frequencies. Therefore, new DOA algorithms cognisant of these factors need to be developed and the performance of the existing algorithms quantified. This work investigates the performance of the Conventional Minimum Variance Distortion-less Look (MVDL), Subspace DOA Estimation Methods of Multiple Signal Classification (MUSIC) and the developed hybrid DOA algorithm on a weather impacted wireless channel. The performance of the proposed Advanced-MUSIC (A-MUSIC) algorithm is compared to the conventional DOA estimation algorithms of Minimum Variance Distortionless Response (MVDR) and the Multiple Signal Classification (MUSIC) algorithms for both NLA and ULA antenna arrays. The developed simulation results show that A-MUSIC shows superior performance compared to the two other algorithms in terms of Signal Noise Ratio (SNR) and the number of antenna elements. The results show performance degradation in a rainfall impacted communication network with the developed algorithm showing better performance degradation

Angle-of-Arrival Measurement Techniques for Enhanced Positioning in Beyond 5G Systems

The new generation of mobile communication systems introduces new methods and technologies that may enhance positioning accuracy in some scenarios when the GNSS system cannot meet the requirements, such as indoor positioning and outdoor autonomous driving. The 3GPP standard and for the first time included the angle measurement as new positioning methods in 5G. The Angle of Arrival (AoA) is the angle measurement method on the uplink direction that can enjoy the new capabilities in 5G systems to enhance the positioning downs to centimeters.The new generation of mobile communication systems introduces new methods and technologies that may enhance positioning accuracy in some scenarios when the GNSS system cannot meet the requirements, such as indoor positioning and outdoor autonomous driving. The 3GPP standard and for the first time included the angle measurement as new positioning methods in 5G. The Angle of Arrival (AoA) is the angle measurement method on the uplink direction that can enjoy the new capabilities in 5G systems to enhance the positioning downs to centimeters. Multiple Signal Classification Method (MUSIC) is a high-accuracy super-resolution algorithm for AoA estimation. The MUSIC method for estimating AoA has many shortcomings that make it unsuitable for a wide variety of scenarios. Correlated multipath signals substantially reduce estimation accuracy. Additionally, this method is a searching algorithm that requires a significant amount of time to resolve AoA. In this thesis, a CASCADE algorithm was proposed to overcome MUSIC's constraints by estimating a coarse range of AoA using a rapid AoA algorithm and then passing that range to the second stage represented by MUSIC to estimate AoA correctly. Multipath signals were eliminated by modifying the proposed CASCADE to detect only the line of sight (LOS), which is the essential path for angular localization. Additionally, the thesis compares many AoA algorithms in the context of 5G systems. A sounding reference signal (SRS) in the mm-wave band was generated according to the 3GPP standards and utilized as the input to those algorithms. A simulation was conducted throughout this thesis by evaluating six AoA algorithms: Bartlet Beamforming, MVDR, MUSIC, ESPRIT, FFT, and the proposed CASCADE method. The results showed that the proposed algorithm achieves the best performance when using less than 64 array antenna elements. On the other hand, FFT alone can provide high accuracy when using an ultra massive antenna system (e.g., 256,512,1024). Additionally, the findings observed the effect of key parameters on the performance of AoA algorithms, such as low SNR, a small number of snapshots (samples), and the effect of multipath signals

Antenna Systems

This book offers an up-to-date and comprehensive review of modern antenna systems and their applications in the fields of contemporary wireless systems. It constitutes a useful resource of new material, including stochastic versus ray tracing wireless channel modeling for 5G and V2X applications and implantable devices. Chapters discuss modern metalens antennas in microwaves, terahertz, and optical domain. Moreover, the book presents new material on antenna arrays for 5G massive MIMO beamforming. Finally, it discusses new methods, devices, and technologies to enhance the performance of antenna systems

Angle of Arrival Estimation Utilising Frequency Diverse Radio Antenna Arrays

The purpose of this research is to investigate a novel way of combining carrier signals that are transmitted successively over Multiple Frequencies (MF) and traditional metrics to improve AoA estimation. Every signal contains three metrics, amplitude, phase, and frequency. To achieve localisation, current systems utilise the metrics of amplitude (also known as Received Signal Strength (RSS)) and phase that resolves the AoA. However, the metric of frequency is mostly used with Orthogonal Frequency-Division Multiplexing (OFDM) to increase the number of RSS and AoA metrics, which is not optimal. This research answers two questions. Can the use of MF improve AoA estimation? Also, how can MF and traditional metrics be combined for AoA estimation? The aim is to prove that the metric of frequency can be utilised more optimally. Therefore, measurements of RSS and AoA are performed in different environments for MF. To perform these measurements, ten frequency diverse Software Defined Radios (SDRs) are employed. A novel technique to time/frequency synchronise the SDRs is developed and presented. Moreover, a ten element Uniform Linear Array (ULA) is designed, simulated and manufactured. The outcomes of this research are two novel algorithms for the MF AoA estimation of a carrier transmitter. Findings of the first algorithm show that the use of MF with the RSS metric performs equally with current systems that have a higher cost and complexity. The second algorithm that utilises MF with the AoA metric demonstrates a significant reduction in the AoA estimation error, compared to current systems. Specifically, for 50\% of the measured cases the AoA estimation error is reduced by 3.7 degrees, while for 95\% of the measured cases the AoA estimation error is reduced by 27 degrees. Hence, this research proves that MF with traditional metrics can reduce system complexity and greatly improve AoA estimation

Journal of Telecommunications and Information Technology, 2009, nr 2

kwartalni

Journal of Telecommunications and Information Technology, 2021, nr 1

kwartalni