Analysis And Optimization For Robust Millimeter Wave Communications
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Analysis and Optimization for Robust Millimeter-Wave Communications
Author: Cristian Tatino
language: en
Publisher: Linköping University Electronic Press
Release Date: 2021-01-13
Spectrum scarcity is a longstanding problem in mobile telecommunications networks. Specifically, accommodating the ever-growing data rate and communications demand in the extensively used spectrum between 800 MHz and 6 GHz is becoming more challenging. For this reason, in the last years, communications in the millimeterwave (mm-wave) frequency range (30-300 GHz) have attracted the interest of many researchers, who consider mm-wave communications a key enabler for upcoming generations of mobile communications, i.e., 5G and 6G. However, the signal propagation in the mm-wave frequency range is subject to more challenging conditions. High path loss and penetration loss may lead to short-range communications and frequent transmission interruptions when the signal path between the transmitter and the receiver is blocked. In this dissertation, we analyze and optimize techniques that enhance the robustness and reliability of mm-wave communications. In the first part, we focus on approaches that allow user equipment (UE) to establish and maintain connections with multiple access points (APs) or relays, i.e., multi-connectivity (MC) and relaying techniques, to increase link failure robustness. In such scenarios, an inefficient link scheduling, i.e., over or under-provisioning of connections, can lead to either high interference and energy consumption or unsatisfied user’s quality of service (QoS) requirements. In the first paper, we propose a novel link scheduling algorithm for network throughput maximization with constrained resources and quantify the potential gain of MC. As a complementary approach, in the second paper, we solve the problem of minimizing allocated resources while satisfying users’ QoS requirements for mm-wave MC scenarios. To deal with the channel uncertainty and abrupt blockages, we propose a learning-based solution, of which the results highlight the tradeoff between reliability and allocated resource. In the third paper, we perform throughput and delay analysis of a multi-user mm-wave wireless network assisted by a relay. We show the benefits of cooperative networking and the effects of directional communications on relay-aided mm-wave communications. These, as highlighted by the results, are characterized by a tradeoff between throughput and delay and are highly affected by the beam alignment duration and transmission strategy (directional or broadcast). The second part of this dissertation focuses on problems related to mm-wave communications in industrial scenarios, where robots and new industrial applications require high data rates, and stringent reliability and latency requirements. In the fourth paper, we consider a multi-AP mm-wave wireless network covering an industrial plant where multiple moving robots need to be connected. We show how the joint optimization of robots’ paths and the robot-AP associations can increase mm-wave robustness by decreasing the number of handovers and avoiding coverage holes. Finally, the fifth paper considers scenarios where robot-AP communications are assisted by an intelligent reflective surface (IRS). We show that the joint optimization of beamforming and trajectory of the robot can minimize the motion energy consumption while satisfying time and communication QoS constraints. Moreover, the proposed solution exploits a radio map to prevent collisions with obstacles and to increase mm-wave communication robustness by avoiding poorly covered areas.
Microscopic Traffic Simulation of Automated Driving
Author: Ivan Postigo
language: en
Publisher: Linköping University Electronic Press
Release Date: 2025-02-25
The introduction of automated driving systems (ADSs) in road transportation systems will affect the traffic flow characteristics, and have ripple effects which will lead to larger societal implications. The traffic flow is characterized by speed, density, and vehicular throughput, which determine the road capacity and the traffic performance in terms of, among others, travel times and delays. A tool used to study traffic flow dynamics and analyze traffic performance is microscopic traffic simulation, which works by describing the interactions between road users to simulate observed traffic phenomena. To use microscopic traffic simulation to evaluate the impact of ADSs on traffic performance, driving models need to be able to simulate driving decisions and behavioral patterns of ADSs. Driving models have been proposed specifically for ADSs, however, it remains to be validated whether these driving models when used in combination with traditional human driving models adequately simulate mixed traffic that includes human drivers and ADSs. Ideally, a clear interpretation of the behavioral assumptions for each type of vehicle should be possible, as these determine the simulation results. However, it is challenging to compare behavioral assumptions when using different driving models to describe different vehicle types. Empirical research has validated that some driving models, such as the intelligent driver car-following model (IDM), are well-suited for describing both human or automated driving when calibrated with the proper data. The aim of this thesis is two fold: to further develop microscopic traffic simulation for the study of mixed traffic, and to evaluate the effects of mixed traffic on motorway traffic performance. To enhance the modeling of mixed traffic, a model for perception is proposed which allows the explicit inclusion of perception errors in driving decisions. Its use, in combination with driving models capable of describing both human and automated driving, enables to make distinctions between human drivers and ADSs both in perception capabilities and in driving behavior. This modeling approach focuses on describing essential differences to simulate mixed traffic and removes risks involved in using different driving models. Simulation experiments are conducted using state-of-the-art tools to evaluate the modeling of perception errors on traffic flow dynamics and to evaluate the effects of mixed traffic on motorway traffic performance.
ICT Analysis and Applications
This book proposes new technologies and discusses future solutions for ICT design infrastructures, as reflected in high-quality papers presented at the 8th International Conference on ICT for Sustainable Development (ICT4SD 2023), held in Goa, India, on August 3–4, 2023. The book covers the topics such as big data and data mining, data fusion, IoT programming toolkits and frameworks, green communication systems and network, use of ICT in smart cities, sensor networks and embedded system, network and information security, wireless and optical networks, security, trust, and privacy, routing and control protocols, cognitive radio and networks, and natural language processing. Bringing together experts from different countries, the book explores a range of central issues from an international perspective.