Cellular networks are becoming more common, this introduces new challenges in dealing with their error prone nature. To improve end-to-end performance when the first link in the connection is wireless, an adaptive timeout based on network conditions is constructed. Relevant network factors are identified by examining data collected by a device located in a vehicle moving around in southern Sweden. Channel Quality Indicator (CQI) is shown to be the primary predictor of errors in the connection. In our datasets, a CQI index of 2 is a very good predictor of an error prone state. The collected data is split into training and evaluation data, the training data is used to construct a model. An adaptive timeout mechanism which uses this model is proposed, the mechanism is shown to be superior in all tested cases in the dataset compared to the optimal static counterpart. Reducing timeouts allows for applications to make new decisions based on new information faster, increasing responsiveness and user satisfaction.

With the emergence of the Internet-of-Things (IoT), communication networks have evolved toward autonomous networks of intelligent devices capable of communicating without direct human intervention. This is known as Machine-to-Machine (M2M) communications. Cellular networks are considered one of the main technologies to support the deployment of M2M communications as they provide extended wireless connectivity and reliable communication links. However, the characteristics and Quality-of-Service (QoS) requirements of M2M communications are distinct from those of conventional cellular communications, also known as Human-to-Human (H2H) communications, that cellular networks were originally designed for. Thus, enabling M2M communications poses many challenges in terms of interference, congestion, spectrum scarcity and energy efficiency. The primary focus is on the problem of resource allocation that has been the interest of extensive research effort due to the fact that both M2M and H2H communications coexist in the cellular network. This requires that radio resources be allocated such that the QoS requirements of both groups are satisfied. In this work, we propose three models to address this problem. In the first model, a two-phase resource allocation algorithm for H2H/M2M coexistence in cellular networks is proposed. The goal is to meet the QoS requirements of H2H traffic and delay-sensitive M2M traffic while ensuring fairness for the delay-tolerant M2M traffic. Simulation results are presented which show that the proposed algorithm is able to balance the demands of M2M and H2H traffic, meet their diverse QoS requirements, and ensure fairness for delay-tolerant M2M traffic. With the growing number of Machine-Type Communication Devices (MTCDs) the problem of spectrum scarcity arises. Hence, Cognitive Radio (CR) is the focus of the second model where clustered Cognitive M2M (CM2M) communications underlaying cellular networks is proposed. In this model, MTCDs are grouped in clusters based on their spatial location and communicate with the Base Station (BS) via Machine-Type Communication Gateways (MTCGs). An underlay CR scheme is implemented where the MTCDs within a cluster share the spectrum of the neighbouring Cellular User Equipment (CUE). A joint resource-power allocation problem is formulated to maximize the sum-rate of the CUE and clustered MTCDs while adhering to MTCD minimum data rate requirements, MTCD transmit power limits, and CUE interference constraints. Simulation results are presented which show that the proposed scheme significantly improves the sum-rate of the network compared to other schemes while satisfying the constraints. Due to the limited battery capacity of MTCDs and diverse QoS requirements of both MTCDs and CUE, Energy Efficiency (EE) is critical to prolonging network lifetime to ensure uninterrupted and reliable data transmission. The third model investigates the power allocation problem for energy-efficient CM2M communications underlaying cellular networks. Underlay CR is employed to manage the coexistence of MTCDs and CUE and exploit spatial spectrum opportunities. Two power allocation problems are proposed where the first targets MTCD power consumption minimization while the second considers MTCD EE maximization subject to MTCD transmit power constraints, MTCD minimum data rate requirements, and CUE interference limits. Simulation results are presented which indicate that the proposed algorithms provide MTCD power allocation with lower power consumption and higher EE than the (Equal Power Allocation) EPA scheme while satisfying the constraints. / Graduate

The ever-growing demands for wireless technologies necessitate the evolution of next generation wireless networks that fulfill the diverse wireless users requirements. However, upscaling existing wireless networks implies upscaling an intrinsic component in the wireless domain; the aggregate network interference. Being the main performance limiting factor, it becomes crucial to develop a rigorous analytical framework to accurately characterize the out-of-cell interference, to reap the benefits of emerging networks. Due to the different network setups and key performance indicators, it is essential to conduct a comprehensive study that unifies the various network configurations together with the different tangible performance metrics. In that regard, the focus of this thesis is to present a unified mathematical paradigm, based on Stochastic Geometry, for large-scale networks with different antenna/network configurations. By exploiting such a unified study, we propose an efficient automated network design strategy to satisfy the desired network objectives. First, this thesis studies the exact aggregate network interference characterization, by accounting for each of the interferers signals in the large-scale network. Second, we show that the information about the interferers symbols can be approximated via the Gaussian signaling approach. The developed mathematical model presents twofold analysis unification for uplink and downlink cellular networks literature. It aligns the tangible decoding error probability analysis with the abstract outage probability and ergodic rate analysis. Furthermore, it unifies the analysis for different antenna configurations, i.e., various multiple-input multiple-output (MIMO) systems. Accordingly, we propose a novel reliable network design strategy that is capable of appropriately adjusting the network parameters to meet desired design criteria. In addition, we discuss the diversity-multiplexing tradeoffs imposed by differently favored MIMO schemes, describe the relation between the diverse network parameters and configurations, and study the impact of temporal interference correlation on the performance of large-scale networks. Finally, we investigate some interference management techniques by exploiting the proposed framework. The proposed framework is compared to the exact analysis as well as intensive Monte Carlo simulations to demonstrate the model accuracy. The developed work casts a thorough inclusive study that is beneficial to deepen the understanding of the stochastic deployment of the next-generation large-scale wireless networks and predict their performance.

Internet goes mobile as billions of users are accessing the Internet through their smartphones. Cellular networks play an essential role in providing “anytime, anywhere” network access as the only large-scale wireless network infrastructure in operation. Mobility support is the salient feature indispensable to ensure seamless Internet connectivity to mobile devices wherever the devices go or are. Cellular network operators deploy a huge number of cell towers over geographical areas each with limited radio coverage. When the device moves out of the radio coverage of its serving cell(s), mobility support is performed to hand over its serving cell(s) to another, thereby ensuring uninterrupted network access.<br>Despite a large success at most places, we uncover that state-of-the-practice mobility support in operational cellular networks suffers from a variety of issues which result in unnecessary performance degradation to mobile devices. In this thesis, we dive into these issues in today’s mobility support and explore possible solutions with no or small changes to the existing network infrastructure.<br>We take a new perspective to study and enhance mobility support. We directly examine, troubleshoot and enhance the underlying procedure of mobility support, instead of higher-layer (application/transport) exploration and optimization in other existing studies. Rather than clean slate network-side solutions, we focus on device-side solutions which are compatible with 3GPP standards and operational network infrastructure, promising immediate benefits without requiring any changes on network side.<br>In particular, we address three technical questions by leveraging the power of the devices. First, how is mobility support performed in reality? We leverage device-side observation to monitor the handoff procedures that happen between the network and the device. We unveil that operator-specific configurations and policies play a decisive role under the standard mechanism and conduct a large-scale measurement study to characterize the extremely complex and diverse handoff configurations used by global operators over the world. Second, what is wrong with the existing mobility support? We conduct model-based reasoning and empirical study to examine network performance issues (e.g., handoff instability and unreachability, missed performance) which are caused by improper handoffs. Finally, how to enhance mobility support? We turn passive devices to proactive devices to enhance mobility support. Specifically, we make a showcase solution which exploits device-side inputs to intervene the default handoff procedure and thus indirectly influence the cell selection decision, thereby improving data speed to mobile devices. All the results in this thesis have been validated or evaluated in reality (over top-tier US carriers like AT&T, Verizon, T-Mobile, some even in global carrier networks).

La tâche de répondre à une demande croissante pour une meilleure qualité de l'expérience utilisateur dans les communications sans fil, est contestée par la quantité d'énergie consommée par les technologies concernées et les méthodes employées. Sans surprise, le problème de la réduction de la consommation d'énergie doit être abordé à diverses couches de l'architecture de réseau et de diverses directions. Cette thèse traite de certains aspects cruciaux de la couche physique de l'architecture de réseau sans fil afin de trouver des solutions efficaces d'énergie. Dans la première partie de cette thèse, nous explorons l'idée de l'efficacité énergétique à un niveau fondamental. A commencer par répondre aux questions telles que: - Qu'est-ce que la forme physique d'information ?, nous construisons un dispositif de communication simple afin d'isoler certaines étapes clés dans le processus physique de la communication et nous dire comment elles affectent l'efficacité énergétique d'une communication système. Dans la deuxième partie, nous utilisons des outils de la géométrie stochastique pour modéliser théoriquement réseaux cellulaires afin d'analyser l'efficacité énergétique du système. L'exploitation de la traçabilité d'une telle modélisation mathématique, nous explorons les conditions dans lesquelles la consommation d'énergie peut être réduite. En outre, dans cette partie, nous introduisons le concept de la mise en cache des données des utilisateurs à la périphérie du réseau (à savoir le final ac BS qui est en contact avec l'utilisateur) et de montrer quantitativement comment la mise en cache peut aider à améliorer l'efficacité énergétique d'un cellulaire réseau. Nous tenons également à ce traitement à un ac Hetnet scénario (à savoir quand il y a plus d'un type de glspl déployé BS) et étudions divers indicateurs de performance clés. Nous explorons également les conditions où l'efficacité énergétique d'un tel système peut être améliorée. Les résultats de thèse fournissent quelques idées clés pour améliorer l'efficacité énergétique dans un réseau cellulaire sans fil contribuant ainsi à l'avancement vers la prochaine génération (5 G) des réseaux cellulaires. / The task of meeting an ever growing demand for better quality of user experience in wireless communications, is challenged by the amount of energy consumed by the technologies involved and the methods employed. Not surprisingly, the problem of reducing energy consumption needs to be addressed at various layers of the network architecture and from various directions. This thesis addresses some crucial aspects of the physical layer of wireless network architecture in order to find energy efficient solutions.In the first part of this thesis, we explore the idea of energy efficiency at a fundamental level. Starting with answering questions such as - emph{What is the physical form of `information'?}, we build a simple communication device in order to isolate certain key steps in the physical process of communication and we comment on how these affect the energy efficiency of a communication system.In the second part, we use tools from stochastic geometry to theoretically model cellular networks so as to analyze the energy efficiency of the system. Exploiting the tractability of such a mathematical modeling, we explore the conditions under which the consumption of energy can be reduced. Further in this part, we introduce the concept of caching users' data at the edge of the network (namely the final ac{BS} that is contact with the user) and show quantitatively how caching can help improve the energy efficiency of a cellular network. We also extend this treatment to a ac{HetNet} scenario (namely when there are more than one type of glspl{BS} deployed) and study various key performance metrics. We also explore the conditions where energy efficiency of such a system can be improved.The results in thesis provide some key ideas to improve energy efficiency in a wireless cellular network thereby contributing to the advancement towards the next generation (5G) cellular networks.

Future cellular networks, the so-called 5G, are expected to provide explosive data volumes and data rates. To meet such a demand, the research communities are investigating new wireless transmission technologies. One of the most promising candidates is in-band full-duplex communications. These communications are characterized by that a wireless device can simultaneously transmit and receive on the same frequency channel. In-band full-duplex communications have the potential to double the spectral efficiencywhen compared to current half duplex systems. The traditional drawback of full-duplex was the interference that leaks from the own transmitter to its own receiver, the so- called self-interference, which renders the receiving signal unsuitable for communication.However, recent advances in self-interference suppression techniques have provided high cancellation and reduced the self-interference to noise floor levels, which shows full-duplex is becoming a realistic technology component of advanced wireless systems. Although in-band full-duplex promises to double the data rate of existing wireless technologies, its deployment in cellular networks is challenging due to the large number of legacy devices working in half-duplex. A viable introduction in cellular networks is offered by three-node full-duplex deployments, in which only the base stations are full-duplex, whereas the user- or end-devices remain half-duplex. However, in addition to the inherent self-interference, now the interference between users, the user-to-user interference, may become the performance bottleneck, especially as the capability to suppress self-interference improves. Due to this new interference situation, user pairing and frequency channel assignment become of paramount importance, because both mechanisms can help to mitigate the user-to-user interference. It is essential to understand the trade-offs in the performance of full-duplex cellular networks, specially three-node full-duplex, in the design of spectral and energy efficient as well as fair mechanisms. This thesis investigates the design of spectral efficient and fair mechanisms to improve the performance of full-duplex in cellular networks. The novel analysis proposed in this thesis suggests centralized and distributed user pairing, frequency channel assignment and power allocation solutions to maximize the spectral efficiency and fairness in future full-duplex cellular networks. The investigations are based on distributed optimization theory with mixed integer-real variables and novel extensions of Fast-Lipschitz optimization. The analysis sheds lights on two fundamental problems of standard cellular networks, namely the spectral efficiency and fairness maximization, but in the new context of full-duplex communications. The results in this thesis provide important understanding in the role of user pairing, frequency assignment and power allocation, and reveal the special behaviourbetween the legacy self-interference and the new user-to-user interference. This thesis can provide input to the standardization process of full-duplex communications, and have the potential to be used in the implementation of future full-duplex in cellular networks. / <p>QC 20170403</p>

Yes / This work integrates a harmonic tuning mechanism in synergy with the GaN HEMT transistor for 5G mobile transceiver applications. Following a theoretical study on the operational behavior of the Class-F power amplifier (PA), a complete amplifier design procedure is described that includes the proposed Harmonic Control Circuits for the second and third harmonics and optimum loading conditions for phase shifting of the drain current and voltage waveforms. The performance improvement provided by the Class-F configuration is validated by comparing the experimental and simulated results. The designed 10W Class-F PA prototype provides a measured peak drain efficiency of 64.7% at 1dB compression point of the PA at 3.6GHz frequency.

In the upcoming years, industrial enterprises are expected to undergo a major transformation, as the Internet of Things (IoT) reaches widespread adoption. A key enabler behind this transformation, known as Industry 4.0, is the 5th generation of cellular networks (5G). Through privately owned networks, enterprises will be able to utilize the 5G technology to tailor the network to meet their needs in terms of security, reliability, and quality of service. Although much of the technology is currently in place, few efforts have been dedicated to help enterprises understand and optimise the value that this new solution brings. One way of making 5G more accessible is through information visualization of its data. Dashboards are today the widely adopted tool for processing data in organisations. This study aimed at examining the affordances and challenges of information visualization of 5G network data in such a tool, in order to make 5G more accessible. A large number of commercial network management dashboards were reviewed in relation to research on effective dashboard design, and a prototype was developed and evaluated with seven user experience experts. Results from the expert review suggests information visualization clearly aided communication of the five visualized network parameters: throughput, latency, availability, coverage, and devices. However, to fully examine the usefulness of the tool, further research on the tool’s fit in an industry context needs to be conducted. / Inom de kommande åren förväntas industriföretag genomgå en stor transformation, i samband med att sakernas internet (engelskans Internet of Things, IoT) når utbredd användning. En viktig möjliggörare bakom denna transformation, känd som Industri 4.0, är den 5:e generationens mobilnät (5G). Genom privatägda mobilnät kommer företag att kunna använda 5G teknologin till att skräddarsy sina nätverk för att tillgodose de egna behoven gällande säkerhet, tillförlitlighet och kvalitet. Trots att mycket av 5G teknologin redan är på plats, har få ansträngningar gjorts för att hjälpa företag förstå och optimera värdet som denna nya lösning medför. Ett sätt som kan göra 5G mer lättförståeligt är genom informationsvisualisering av dess data. Dashboards är idag det mest använda verktyget för att bearbeta data i organisationer. Denna studie ämnade därför att undersöka fördelarna och nackdelarna med informationsvisualisering av data från ett privat 5G-nät i ett sådant verktyg. Ett stort antal kommersiella dashboards för nätverksprestationshantering granskades i förhållande till forskning inom området för effektiv design av dashboards, och en prototyp utvecklades och utvärderades med sju experter inom användarupplevelse. Resultaten från expertgranskningen tyder på att användningen av informationsvisualisering klart hjälpte i kommunikationen av de fem visualiserade nätverksparametrarna: genomströmning, svarstid, tillgänglighet, täckning och uppkopplade enheter. Däremot krävs ytterligare forskning kring verktygets roll i industriell kontext för att kunna göra en fullständig granskning av verktygets användbarhet.

<p> Telemedicine traffic transmission over wireless cellular networks has gained in importance during the last few years. Most of the current research in the field has focused on software and hardware implementations for telemedicine transmission, without discussing the case of simultaneous transmission of both urgent telemedicine traffic and regular multimedia traffic over the network.</p> <p> Due to the fact that telemedicine traffic carries critical information regarding the patients' condition, it is vitally important that this traffic has highest transmission priority in comparison to all other types of traffic in the cellular network. However, the need for expedited and correct transmission of telemedicine traffic calls for a guaranteed bandwidth to telemedicine users. This creates a tradeoff between the satisfaction of the very strict Quality of Service (QoS) requirements of telemedicine traffic and the loss of the guaranteed bandwidth in the numerous cases when it is left unused, due to the infrequent nature of telemedicine traffic. This waste of the bandwidth may lead to a lack of sufficient bandwidth for regular traffic, hence degrading its QoS.</p> <p> To resolve this complex problem, in this thesis, we propose a) an adaptive bandwidth reservation scheme based on road map information and on users' mobility, and b) a fair scheduling scheme for video traffic transmission over wireless cellular networks. The proposed combination of the two schemes, which is evaluated over a hexagonal cellular structure, is shown to achieve high channel bandwidth utilization while offering full priority to telemedicine traffic.</p> / Thesis / Master of Applied Science (MASc)

Yes / This study aims to introduce a new phased array design with improved radiation properties for future cellular networks. The procedure of the array design is simple and has been accomplished on a low-cost substrate material while offering several interesting features with high performance. Its schematic involves eight air-filled slot-loop metal-ring elements with a 1 × 8 linear arrangement at the top edge of the 5G smartphone mainboard. Considering the entire board area, the proposed antenna elements occupy an extremely small area. The antenna elements cover the range of 21–23.5 GHz sub-mm-wave 5G bands. Due to the air-filled function in the configurations of the elements, low-loss and high-performance radiation properties are observed. In addition, the fundamental characteristics of the introduced array are insensitive to various types of substrates. Moreover, its radiation properties have been compared with conventional arrays and better results have been observed. The proposed array appears with a simple design, a low complexity profile, and its attractive broad impedance bandwidth, end-fire radiation mode, wide beam steering, high radiation coverage, and stable characteristics meet the needs of 5G applications in future cellular communications. Additionally, the smartphone array design offers sufficient efficiency when it comes to the appearance and integration of the user’s components. Thus, it could be used in 5G hand-portable devices.