Literatura académica sobre el tema "Cross Link Interference (CLI)"

In this paper, we propose a novel interference alignment (IA) technique for an in-band full-duplex (IBFD) multiple-input multiple-output (MIMO) cellular network where a base station (BS) and user equipment (UE) are equipped with multiple antennas, and the local channel state information (CSI) is available at all nodes. Considering a practical IBFD MIMO cellular network, it is assumed that only the BS operates with full-duplex (FD) communication while UE operate in half-duplex (HD) mode. These IBFD networks introduce a new type of interference called cross-link interference (CLI), in which uplink UE affects downlink UE. The proposed IA technique consists of two symmetric IA schemes according to the number of antennas in the uplink and downlink UE, and both schemes effectively mitigate CLI in the IBFD MIMO network. It is worth noting that both IA schemes are adaptively applicable according to the network’s quality-of-service (QoS) requirements, such as uplink and downlink traffic demands. Furthermore, we theoretically characterize and prove the achievable sum-degrees-of-freedom (DoF) of the proposed IA technique. Simulation results show that the proposed IA technique significantly improves the sum rate performance compared to conventional HD communications (multi-user MIMO) while achieving the same achievable DoF as the interference-free IBFD MIMO network.

Tor is a popular privacy-enhancing technology that allows anonymous communication using onion routing. However, such technologies are only helpful if used; therefore, performance is an important aspect. One of the main performance bottlenecks of Tor is the cross-circuit interference (CCI) problem. Tor multiplexes multiple circuits over a single Transport Layer Security (TLS) 1.2 connection if they share a path segment (link). Therefore, they have the same congestion window, which can yield unfair bandwidth allocation. However, there has been little work in understanding this problem in more depth. This paper investigates the number of simultaneously shared links in the current Tor network, which are the root cause of CCI. We developed a novel shared links simulator called SALSA to investigate this problem. Our results show that 3.7 % of active links are shared, and the involving Onion Routers (ORs) have the most common bandwidth capabilities. Additionally, we show that the internal circuits and exit policy influence the CCI problem. Furthermore, we model the number of shared links when the demand grows further and show that the number of shared links can go up to 16 %. Finally, we run Shadow simulations with a 25 % down-scaled Tor network and show that a network without shared links is faster.

Although all bilinguals encounter cross-language interference (CLI), some bilinguals are more susceptible to interference than others. Here, we report on language performance of late bilinguals (Russian/German) on two bilingual tasks (interview, verbal fluency), their language use and switching habits. The only between-group difference was CLI: one group consistently produced significantly more errors of CLI on both tasks than the other (thereby replicating our findings from a bilingual picture naming task). This striking group difference in language control ability can only be explained by differences in cognitive control, not in language proficiency or language mode.

The performance of multiple input multiple output (MIMO) wireless networks is limited mainly by concurrent interference among sensor nodes. Effective link scheduling algorithms with the technology of successive interference cancellation (SIC) can maximize throughput in MIMO wireless networks. Most previous works on link scheduling in MIMO wireless networks did not consider SIC. In this paper, we propose a MIMO-SIC (MSIC) algorithm under the SINR model. First, a mathematical framework is established for the cross-layer optimization of routing and scheduling, with constraints of traffic balance and link capacity. Second, the interference regions are divided to characterize the level of interference between links. Finally, we propose a distributed link scheduling algorithm based on MSIC to eliminate the interference between competing links in the MIMO network. Experimental results show that the MSIC algorithm can increase the end-to-end throughput per unit by approximately 73% on average compared with non-SIC algorithms.

Abstract The ability of serum factors to cross-link labeled mouse monoclonal antibody (mAb) of irrelevant specificity (mAb FN61, subclass IgG1) to different particle types coated with sheep IgG, bovine gamma-globulin, or mAb FN61 was measured simultaneously by flow cytometry. Significant interference with mAb FN61-coated particles was detected in 53 of 101 sera. Of the 30 sera showing the most pronounced interference, 23 were characterized by an even stronger cross-linking to particles coated with bovine gamma-globulin. These were designated type 1 sera. Seven sera, designated type 2, displayed a dominant interference with the mAb FN61-coated particles. The interference reaction in the two serum types was characterized by different kinetics, dependence on particle concentration, and response to blocking agents. The interference was minimized by addition of 500 micrograms of bovine gamma-globulin and 50 micrograms of mAb HH1 (IgG1) of irrelevant specificity per 10 microL of serum sample in a final assay volume of 100 microL.

Road crack detection is one of the important issues in the field of traffic safety and urban planning. Currently, road damage varies in type and scale, and often has different sizes and depths, making the detection task more challenging. To address this problem, we propose a Cross-Attention-guided Feature Alignment Network (CAFANet) for extracting and integrating multi-scale features of road damage. Firstly, we use a dual-branch visual encoder model with the same structure but different patch sizes (one large patch and one small patch) to extract multi-level damage features. We utilize a Cross-Layer Interaction (CLI) module to establish interaction between the corresponding layers of the two branches, combining their unique feature extraction capability and contextual understanding. Secondly, we employ a Feature Alignment Block (FAB) to align the features from different levels or branches in terms of semantics and spatial aspects, which significantly improves the CAFANet’s perception of the damage regions, reduces background interference, and achieves more precise detection and segmentation of damage. Finally, we adopt multi-layer convolutional segmentation heads to obtain high-resolution feature maps. To validate the effectiveness of our approach, we conduct experiments on the public CRACK500 dataset and compare it with other mainstream methods. Experimental results demonstrate that CAFANet achieves excellent performance in road crack detection tasks, which exhibits significant improvements in terms of F1 score and accuracy, with an F1 score of 73.22% and an accuracy of 96.78%.

Le TDD dynamique joue un rôle crucial dans les réseaux 5G, adaptant les ressources aux besoins variés. Il améliore l'efficacité spectrale en allouant dynamiquement des créneaux horaires pour les transmissions montantes et descendantes en fonction de la demande de trafic et des conditions de canal. Cette allocation dynamique de fréquence assure une utilisation efficace du spectre et prend en charge une connectivité massive, une latence faible et les exigences de la qualité de service. Son rôle dans l'agrégation de porteuses maximise les débits de données et la capacité du réseau, soulignant son importance dans les technologies de communication sans fil avancées.Cependant, le TDD dynamique est confronté à un défi majeur : l'Interférence des liens croisés. Ce type d'interférence se produit lorsque les transmissions montantes et descendantes partagent les mêmes bandes de fréquences, provoquant des interférences.Cette interférence comprend l'interférence de Station de Base à Station de Base (BS-to-BS) ou du lien descendant au lien montant (DL-to-UL) ainsi que l'interférence d'Équipement Utilisateur à Équipement Utilisateur (UE-to-UE) ou du lien montant vers le lien descendant (UL- to-DL). Dans l'interférence DL-to-UL, les transmissions descendantes débordent dans les bandes des transmissions montantes, dégradant la communication montante. À l'inverse, l'interférence UL-to-DL se produit lorsque les transmissions montantes interfèrent avec la réception des transmissions descendantes.Gérer efficacement ces interférences est crucial pour la performance et la fiabilité d'un système TDD dynamique.Ce mémoire vise à libérer tout le potentiel du TDD dynamique en surmontant les défis posés par les interférences des liens croisés grâce à une analyse rigoureuse et des méthodologies innovantes. La recherche ne se contente pas de faire progresser la technologie TDD dynamique, elle pionnière des solutions applicables à divers contextes de communication, stimulant des stratégies innovantes d'alignement d'interférence dans des scénarios variés.Le mémoire se divise en plusieurs parties. La première pose les bases avec la définition du problème et les concepts théoriques essentiels. La deuxième partie examine les conditions de faisabilité de l'alignement des interférences. Ces conditions sont exprimées en fonction de la dimension du problème et établissent le degré de liberté (DoF) atteignable, représentant le nombre de flux de données possibles. Elle explore l'alignement d'interférence dans des scénarios centralisés, en considérant à la fois les canaux MIMO en rang complet et réduit, et aborde des complexités du monde réel. De plus, elle étend l'exploration à un scénario distribué, offrant une compréhension réaliste des complexités de la communication. La troisième partie se concentre sur les techniques d'optimisation, en particulier le beamforming. Elle introduit le Zero Forcing (ZF) beamforming pour les utilisateurs, alignant l'interférence dans les systèmes TDD dynamique. Elle met l'accent sur l'impact de l'interférence des liens croisés entre utilisateurs et présente les améliorations apportées par les algorithmes WMMSE. De plus, elle explore l'optimisation de l'allocation de puissance en utilisant l'algorithme Water-Filling, évaluant la performance du Zero Forcing Beamforming et de l'algorithme WMMSE en fonction de cette approche d'optimisation de puissance<br>Dynamic Time Division Duplexing (DynTDD) is pivotal in 5th generation (5G) networks, adapting resources to diverse needs. It enhances Spectral Efficiency (SE) by dynamically allocating time slots for Uplink (UL) and Downlink (DL) transmissions based on traffic demand and channel conditions. This dynamic frequency allocation ensures efficient spectrum use and supports massive connectivity, low latency, and Quality-of-Service (QoS) requirements. Its role in carrier aggregation maximizes data rates and capacity, highlighting its importance in advanced wireless communication technologies.However, DynTDD faces a significant challenge: cross-link interference (CLI). CLI occurs when UL and DL transmissions share the same frequency bands, leading to interference.CLI comprises base station to base station (BS-to-BS) or downlink to uplink (DL-to-UL) interference and user equipment to user equipment (UE-to-UE) or uplink to downlink (UL-to-DL) interference. In DL-to-UL interference, DL transmissions spill into UL bands, degrading UL communication. Conversely, UL-to-DL interference occurs when UL transmissions interfere with DL reception.Effectively managing CLI is crucial for DynTDD's performance and reliability.This thesis aims to unleash the full potential of DynTDD by overcoming CLI challenges through rigorous analysis and innovative methodologies. The research not only advances DynTDD technology but also pioneers solutions applicable to various communication contexts, driving innovative interference alignment strategies across diverse scenarios.The study in this thesis is divided into multiple segments. The first part establishes the foundation with the problem definition and essential theoretical concepts. The second part delves into the conditions determining the feasibility of interference alignment. These conditions are expressed in terms of the problem dimension and establish the achievable Degree of Freedom (DoF), representing the number of data streams. It explores interference alignment in centralized scenarios, considering both full-rank and reduced-rank Multiple-Input Multiple-Output (MIMO) Interference Broadcast Multiple Access Channel-Interference Channel (IBMAC-IC), addressing real-world complexities. Additionally, it extends the exploration to a distributed scenario, providing a realistic understanding of communication complexities. The third part focuses on optimization techniques, specifically beamforming. It introduces Zero Forcing (ZF) beamforming for both DL and UL User Equipment (UE)s to align CLI in DynTDD systems. It emphasizes the impact of UE-to-UE interference and presents improvements brought by the Weighted Minimum Mean Square Error (WMMSE) algorithms. Furthermore, it explores power allocation optimization using the water-filling algorithm

El presente proyecto de investigación muestra el estudio realizado en una red de transporte microondas de un operador local de telecomunicaciones que aplica el uso de la polarización cruzada o también llamado polarización co-canal con el fin de verificar que existe una duplicidad del ancho de banda y por ende un mejoramiento en la red de transporte, a través del manejo de aplicación de XPIC. Para verificar el mejoramiento de un enlace, hay que considerar ciertos parámetros de radio que nos ayudaran a determinar el comportamiento del mismo, como son el nivel de XPD, nivel de RSL, Margen de desvanecimiento y disponibilidad del enlace. Dentro del estudio se está considerando los factores externos que afectan a un enlace microondas con el uso de XPIC como fallas en instalación, climas por región, obstrucciones en afectación de línea de vista, así como también estudiaremos la parte de simulación con los parámetros de radio involucrados que podrían afectar a poder duplicar la capacidad del enlace, y se mostrará un caso real para verificar el tráfico. This research project shows a study in a network of microwave complimentary local telecommunications operator that applies the use of cross polarization also called co-channel polarization in order to verify that there is a duplication of bandwidth and hence an improvement in the transport network, by managing application XPIC. To verify the improvement of a link, consider certain parameters within which we help to determine the behavior of the same, as are the level of XPD, level RSL, fade margin and link availability. Inside the studio is considering external factors affecting a microwave link using XPIC as faulty installation, climates region affectation obstructions in line of sight, the radio parameters were studied in the part that involved simulation could affect the ability to double bond, and show a real case to verify traffic.

The IEEE 802.11 standard was not initially designed to provide multi-hop capabilities. Therefore, providing a proper traffic performance in Multi-Hop IEEE 802.11 Wireless Networks (MIWNs) becomes a significant challenge. The approach followed in this thesis has been focused on the routing layer in order to obtain applicable solutions not dependent on a specific hardware or driver. Nevertheless, as is the case of most of the research on this field, a cross-layer design has been adopted. Therefore, one of the first tasks of this work was devoted to the study of the phenomena which affect the performance of the flows in MIWNs. Different estimation methodologies and models are presented and analyzed. The first main contribution of this thesis is related to route creation procedures. First, FB-AODV is introduced, which creates routes and forwards packets according to the flows on the contrary to basic AODV which is destination-based. This enhancement permits to balance the load through the network and gives a finer granularity in the control and monitoring of the flows. Results showed that it clearly benefits the performance of the flows. Secondly, a novel routing metric called Weighted Contention and Interference routing Metric (WCIM) is presented. In all analyzed scenarios, WCIM outperformed the other analyzed state-of-the-art routing metrics due to a proper leveraging of the number of hops, the link quality and the suffered contention and interference. The second main contribution of this thesis is focused on route maintenance. Generally, route recovery procedures are devoted to the detection of link breaks due to mobility or fading. However, other phenomena like the arrival of new flows can degrade the performance of active flows. DEMON, which is designed as an enhancement of FB-AODV, allows the preemptive recovery of degraded routes by passively monitoring the performance of active flows. Results showed that DEMON obtains similar or better results than other published solutions in mobile scenarios, while it clearly outperforms the performance of default AODV under congestion Finally, the last chapter of this thesis deals with channel assignment in multi-radio solutions. The main challenge of this research area relies on the circular relationship between channel assignment and routing; channel assignment determines the routes that can be created, while the created routes decide the real channel diversity of the network and the level of interference between the links. Therefore, proposals which join routing and channel assignment are generally complex, centralized and based on traffic patterns, limiting their practical implementation. On the contrary, the mechanisms presented in this thesis are distributed and readily applicable. First, the Interference-based Dynamic Channel Assignment (IDCA) algorithm is introduced. IDCA is a distributed and dynamic channel assignment based on the interference caused by active flows which uses a common channel in order to assure connectivity. In general, IDCA leads to an interesting trade-off between connectivity preservation and channel diversity. Secondly, MR-DEMON is introduced as way of joining channel assignment and route maintenance. As DEMON, MR-DEMON monitors the performance of the active flows traversing the links, but, instead of alerting the source when noticing degradation, it permits reallocating the flows to less interfered channels. Joining route recovery instead of route creation simplifies its application, since traffic patterns are not needed and channel reassignments can be locally decided. The evaluation of MR-DEMON proved that it clearly benefits the performance of IDCA. Also, it improves DEMON functionality by decreasing the number of route recoveries from the source, leading to a lower overhead.<br>El estándar IEEE 802.11 no fue diseñado inicialmente para soportar capacidades multi-salto. Debido a ello, proveer unas prestaciones adecuadas a los flujos de tráfico que atraviesan redes inalámbricas multi-salto IEEE 802.11 supone un reto significativo. La investigación desarrollada en esta tesis se ha centrado en la capa de encaminamiento con el objetivo de obtener soluciones aplicables y no dependientes de un hardware específico. Sin embargo, debido al gran impacto de fenómenos y parámetros relacionados con las capas físicas y de acceso al medio sobre las prestaciones de los tráficos de datos, se han adoptado soluciones de tipo cross-layer. Es por ello que las primeras tareas de la investigación, presentadas en los capítulos iniciales, se dedicaron al estudio y caracterización de estos fenómenos. La primera contribución principal de esta tesis se centra en mecanismos relacionados con la creación de las rutas. Primero, se introduce una mejora del protocolo AODV, que permite crear rutas y encaminar paquetes en base a los flujos de datos, en lugar de en base a los destinos como se da en el caso básico. Esto permite balacear la carga de la red y otorga un mayor control sobre los flujos activos y sus prestaciones, mejorando el rendimiento general de la red. Seguidamente, se presenta una métrica de encaminamiento sensible a la interferencia de la red y la calidad de los enlaces. Los resultados analizados, basados en la simulación de diferentes escenarios, demuestran que mejora significativamente las prestaciones de otras métricas del estado del arte. La segunda contribución está relacionada con el mantenimiento de las rutas activas. Generalmente, los mecanismos de mantenimiento se centran principalmente en la detección de enlaces rotos debido a la movilidad de los nodos o a la propagación inalámbrica. Sin embargo, otros fenómenos como la interferencia y congestión provocada por la llegada de nuevos flujos pueden degradar de forma significativa las prestaciones de los tráficos activos. En base a ello, se diseña un mecanismo de mantenimiento preventivo de rutas, que monitoriza las prestaciones de los flujos activos y permite su reencaminamiento en caso de detectar rutas degradadas. La evaluación de esta solución muestra una mejora significativa sobre el mantenimiento de rutas básico en escenarios congestionados, mientras que en escenarios con nodos móviles obtiene resultados similares o puntualmente mejores que otros mecanismos preventivos diseñados específicamente para casos con movilidad. Finalmente, el último capítulo de la tesis se centra en la asignación de canales en entornos multi-canal y multi-radio con el objetivo de minimizar la interferencia entre flujos activos. El reto principal en este campo es la dependencia circular que se da entre la asignación de canales y la creación de rutas: la asignación de canales determina los enlaces existentes la red y por ello las rutas que se podrán crear, pero son finalmente las rutas y los tráficos activos quienes determinan el nivel real de interferencia que se dará en la red. Es por ello que las soluciones que proponen unificar la asignación de canales y el encaminamiento de tráficos son generalmente complejas, centralizadas y basadas en patrones de tráfico, lo que limita su implementación en entornos reales. En cambio, en nuestro caso adoptamos una solución distribuida y con mayor aplicabilidad. Primero, se define un algoritmo de selección de canales dinámico basado en la interferencia de los flujos activos, que utiliza un canal común en todos los nodos para asegurar la conectividad de la red. A continuación, se introduce un mecanismo que unifica la asignación de canales con el mantenimiento preventivo de las rutas, permitiendo reasignar flujos degradados a otros canales disponibles en lugar de reencaminarlos completamente. Ambas soluciones demuestran ser beneficiosas en este tipo de entornos.

The Queensland University of Technology (QUT) allows the presentation of theses for the Degree of Doctor of Philosophy in the format of published or submitted papers, where such papers have been published, accepted or submitted during the period of candidature. This thesis is composed of ten published /submitted papers and book chapters of which nine have been published and one is under review. This project is financially supported by an Australian Research Council (ARC) Discovery Grant with the aim of investigating multilevel topologies for high quality and high power applications, with specific emphasis on renewable energy systems. The rapid evolution of renewable energy within the last several years has resulted in the design of efficient power converters suitable for medium and high-power applications such as wind turbine and photovoltaic (PV) systems. Today, the industrial trend is moving away from heavy and bulky passive components to power converter systems that use more and more semiconductor elements controlled by powerful processor systems. However, it is hard to connect the traditional converters to the high and medium voltage grids, as a single power switch cannot stand at high voltage. For these reasons, a new family of multilevel inverters has appeared as a solution for working with higher voltage levels. Besides this important feature, multilevel converters have the capability to generate stepped waveforms. Consequently, in comparison with conventional two-level inverters, they present lower switching losses, lower voltage stress across loads, lower electromagnetic interference (EMI) and higher quality output waveforms. These properties enable the connection of renewable energy sources directly to the grid without using expensive, bulky, heavy line transformers. Additionally, they minimize the size of the passive filter and increase the durability of electrical devices. However, multilevel converters have only been utilised in very particular applications, mainly due to the structural limitations, high cost and complexity of the multilevel converter system and control. New developments in the fields of power semiconductor switches and processors will favor the multilevel converters for many other fields of application. The main application for the multilevel converter presented in this work is the front-end power converter in renewable energy systems. Diode-clamped and cascade converters are the most common type of multilevel converters widely used in different renewable energy system applications. However, some drawbacks – such as capacitor voltage imbalance, number of components, and complexity of the control system – still exist, and these are investigated in the framework of this thesis. Various simulations using software simulation tools are undertaken and are used to study different cases. The feasibility of the developments is underlined with a series of experimental results. This thesis is divided into two main sections. The first section focuses on solving the capacitor voltage imbalance for a wide range of applications, and on decreasing the complexity of the control strategy on the inverter side. The idea of using sharing switches at the output structure of the DC-DC front-end converters is proposed to balance the series DC link capacitors. A new family of multioutput DC-DC converters is proposed for renewable energy systems connected to the DC link voltage of diode-clamped converters. The main objective of this type of converter is the sharing of the total output voltage into several series voltage levels using sharing switches. This solves the problems associated with capacitor voltage imbalance in diode-clamped multilevel converters. These converters adjust the variable and unregulated DC voltage generated by renewable energy systems (such as PV) to the desirable series multiple voltage levels at the inverter DC side. A multi-output boost (MOB) converter, with one inductor and series output voltage, is presented. This converter is suitable for renewable energy systems based on diode-clamped converters because it boosts the low output voltage and provides the series capacitor at the output side. A simple control strategy using cross voltage control with internal current loop is presented to obtain the desired voltage levels at the output voltage. The proposed topology and control strategy are validated by simulation and hardware results. Using the idea of voltage sharing switches, the circuit structure of different topologies of multi-output DC-DC converters – or multi-output voltage sharing (MOVS) converters – have been proposed. In order to verify the feasibility of this topology and its application, steady state and dynamic analyses have been carried out. Simulation and experiments using the proposed control strategy have verified the mathematical analysis. The second part of this thesis addresses the second problem of multilevel converters: the need to improve their quality with minimum cost and complexity. This is related to utilising asymmetrical multilevel topologies instead of conventional multilevel converters; this can increase the quality of output waveforms with a minimum number of components. It also allows for a reduction in the cost and complexity of systems while maintaining the same output quality, or for an increase in the quality while maintaining the same cost and complexity. Therefore, the asymmetrical configuration for two common types of multilevel converters – diode-clamped and cascade converters – is investigated. Also, as well as addressing the maximisation of the output voltage resolution, some technical issues – such as adjacent switching vectors – should be taken into account in asymmetrical multilevel configurations to keep the total harmonic distortion (THD) and switching losses to a minimum. Thus, the asymmetrical diode-clamped converter is proposed. An appropriate asymmetrical DC link arrangement is presented for four-level diode-clamped converters by keeping adjacent switching vectors. In this way, five-level inverter performance is achieved for the same level of complexity of the four-level inverter. Dealing with the capacitor voltage imbalance problem in asymmetrical diodeclamped converters has inspired the proposal for two different DC-DC topologies with a suitable control strategy. A Triple-Output Boost (TOB) converter and a Boost 3-Output Voltage Sharing (Boost-3OVS) converter connected to the four-level diode-clamped converter are proposed to arrange the proposed asymmetrical DC link for the high modulation indices and unity power factor. Cascade converters have shown their abilities and strengths in medium and high power applications. Using asymmetrical H-bridge inverters, more voltage levels can be generated in output voltage with the same number of components as the symmetrical converters. The concept of cascading multilevel H-bridge cells is used to propose a fifteen-level cascade inverter using a four-level H-bridge symmetrical diode-clamped converter, cascaded with classical two-level Hbridge inverters. A DC voltage ratio of cells is presented to obtain maximum voltage levels on output voltage, with adjacent switching vectors between all possible voltage levels; this can minimize the switching losses. This structure can save five isolated DC sources and twelve switches in comparison to conventional cascade converters with series two-level H bridge inverters. To increase the quality in presented hybrid topology with minimum number of components, a new cascade inverter is verified by cascading an asymmetrical four-level H-bridge diode-clamped inverter. An inverter with nineteen-level performance was achieved. This synthesizes more voltage levels with lower voltage and current THD, rather than using a symmetrical diode-clamped inverter with the same configuration and equivalent number of power components. Two different predictive current control methods for the switching states selection are proposed to minimise either losses or THD of voltage in hybrid converters. High voltage spikes at switching time in experimental results and investigation of a diode-clamped inverter structure raised another problem associated with high-level high voltage multilevel converters. Power switching components with fast switching, combined with hard switched-converters, produce high di/dt during turn off time. Thus, stray inductance of interconnections becomes an important issue and raises overvoltage and EMI issues correlated to the number of components. Planar busbar is a good candidate to reduce interconnection inductance in high power inverters compared with cables. The effect of different transient current loops on busbar physical structure of the high-voltage highlevel diode-clamped converters is highlighted. Design considerations of proper planar busbar are also presented to optimise the overall design of diode-clamped converters.

碩士<br>國立中正大學<br>通訊工程研究所<br>106<br>In the dynamic time-division duplexing system architecture, the base station can determine the direction of transmission according to the traffic of the downlink /uplink to improve the spectral efficiency. However, when the transmission directions between the base stations are different, cross link interference occurs. Cross link interference is divided into two types: interference of the downlink transmission base station to the uplink receiving base station and interference of the user of the uplink transmission to the user of the downlink reception. This paper aims to study the reduction of cross-link interference from base stations to base stations. There are many methods for mitigating interference across links, including power control, hybrid TDD, beam coordination, scheduling coordination. The paper studies the method of beam coordination. The research of this thesis studies the beam coordination on the ITRI system level simulation platform with UMA (urban macro) as the scene model. In the beam coordination, it is necessary to decide which TRP needs to coordinate with each other to mitigate cross link interference. Therefore, this paper proposes a method of TRP grouping and observes the system communication quality that can be improved when the maximum TRP number of different groups is improved. The better the effect of increasing the maximum TRP number of the group, but the trade-off between the complexity of the system beam coordination and the coordinated time delay. After grouping, the TRP in the group needs to be designed for beam coordination. This paper proposes two methods of beam coordination for beam coordination. First, use the beam-to-beam interference table established in advance to quickly select the beam to be used. Then, the proportional fair scheduling is used to select the users to be served from the selected wave numbers, and the time required for the proportional fair scheduling to select the users is reduced, so that the beam-coordinated beam selection is more efficient. The beam selected by the two methods has about 41% of the same beam, about 38% is the adjacent beam, and the method 1 is lower than the spectrum efficiency of the method 2 by about 2%, but the advantage of the first method is that time and complexity required to select a service to be served from the beam to be used can be significantly reduced. From the simulation results, it can be seen that beam coordination can effectively improve cross link interference. Using the TRP grouping method and beam coordination method of this paper, the signal interference noise ratio is improved by about 20dB. By replacing the anchor TRP in the group and observing the spectral efficiency of the TRP, it can be seen that the anchor TRP will have better spectral efficiency in the group, and the anchor TRP will be about 2 times better than the low priority TRP. Therefore, it is fairer for the TRP in the group to take turns as the anchor TRP.

碩士<br>國立中正大學<br>通訊工程研究所<br>106<br>3GPP, 3rd Generation Partnership Project, is an internationally recognized communication standards development organization. Since Rel-15, Release 15, has completed the technical research and standard specification for 5th Generation Mobile Communication New Radio, 5G-NR. In order to be able to participate in the performance indicators required by the international standard competition, the implementation of System Level Simulator, SLS, is necessary and important. For 3GPP 5G-NR, Flexible Duplex in particular is what this thesis mainly focuses. Therefore, this work cooperates with Industrial Technology Research Institute, ITRI, Information and Communications Research Laboratories and implements a 3GPP 5G-NR Flexible Duplex SLS on their original 4G-LTE SLS. The goal of 5G-NR Flexible Duplex is to have the most flexible spectrum resource usage in the NR frame architecture, increasing spectrum utilization. Furthermore, unpaired spectrum system, Time Division Duplex (TDD), in Flexible Duplex is also what this thesis mainly focuses. Although 5G-NR Flexible Duplex in TDD system could let all base stations choose their uplink and downlink directions flexibly to improve user packet throughput (UPT) and Resource Utilization (RU), the directions between adjacent base station or users may be different which will cause cross-link interference (CLI) seriously. The CLI will affect base station or users’ transmission quality seriously. Therefore, in addition to implementing 3GPP 5G-NR Numerology and slot format and TDD configuration, the most important thing is to implement cross-link interference calculation on the simulation platform. Finally, in order to reduce the simulation time of calculating a large number of interference channels to improve the simulation efficiency, a new method is proposed to accelerate the simulation time by using initial screening interference channels. At last, the 3GPP 5G-NR Flexible Duplex SLS implemented in this thesis could enable users who use this platform to observe new communication technologies in wireless network systems effectively, including average transmission data rate of the base stations, traffic impact, user packet throughput, latency, fairness with large number of base stations interacting with a large number of user equipment. Key words: 5G NR, Flexible Duplex, TDD configuration, Cross-link interference, Accelerate the simulation platform, System Level Simulator

A novel adaptation of independent component analysis controls both cross-polarization and inter-symbol interference in a direct-detection link using Stokes vector modulation. 30-Gb/s experiments confirm polarization de-rotation and near-error-free transmission.