This work presents the foundations of a tool created for the simulation and management of airspaces according to the U-space regulations proposed by the European Union for UAV traffic. The tool will provide a realistic simulation of the flight of numerous UAVs in an urban scenario, with the aim of simplifying and reducing the cost of the development and verification process of all the systems involved, as well as anticipating possible conflicts before deploying a solution in the real world. The tool has been built on one of the most advanced physics simulators currently available, Isaac Sim, which offers numerous tools for experiment analysis, allowing multiple tasks to be executed in parallel in a hyper-realistic environment.

To ensure unmanned aerial vehicle (UAV) swarm safety in areas lacking satellite navigation, accurate localization must be achieved through alternative methods such as relative positioning and clustering. A key challenge involves balancing higher localization accuracy with lower computational complexity, especially in urban environments. Additionally, maintaining up-to-date data transmission to ground stations is critical for real-time localization in dynamic scenarios.This paper proposes a cooperative relative localization scheme based on clustering for UAV swarms. The proposal employs the degree centrality metric to form clusters and connectivity information for cluster head selections, and balances intra-cluster cooperation with inter-cluster packet loss, ensuring the freshness of transmitted data.A first evaluation of the proposed scheme allows us to venture that it will achieve better performance (in terms of mean square error) compared to state-of-the-art techniques for relative localization of UAV swarms.

The assessment of learning outcomes is a key concept in the European Credit Transfer and Accumulation System (ECTS) since credits are awarded when the assessment shows the competences which were aimed at have been developed at an appropriate level. This paper describes a study which was first part of the Bologna Experts Team-Spain project and then developed as an independent study. It was carried out with the overall goal to gain experience in the assessment of learning outcomes. More specifically it aimed at 1) designing procedures for the assessment of learning outcomes related to these compulsory generic competences; 2) testing some basic psychometric features that an assessment device with some consequences for the subjects being evaluated needs to prove; 3) testing different procedures of standard setting, and 4) using assessment results as orienting feedback to students and their tutors. The process of development of tests to carry out the assessment of learning outcomes is described as well as some basic features regarding their reliability and validity. First conclusions on the comparison of the results achieved at two academic levels are also presented.

Disaster management is one of the most promising application fields of wireless sensor networks. In this work we focus on forest fire fighting operations. The role of the sensor network deployed in this scenario will consist in obtaining a representation (or a model) of the fire fronts, and distribute it to the firefighters in the area, in such a way they are aware of the risks they are assuming at each time. To achieve it, sensor nodes are able to determine their position, to detect the presence of fire (by monitoring the evolution of the ambient temperature), and to distribute this information wirelessly through the network. In this way, each firefighter maintains a fire representation consisting of a list of circles centered at the received positions. In this paper, we propose and analyze three criteria to assign the size of these circles. Simulation results show that a dynamic approach based on network density perceived by a node detecting fire offers an accurate approximation to the forest fire, without introducing a significant overhead.

Computer performance has significantly increased in recent years and, consequently, communication subsystems have become bottlenecks within systems. To counter this problem, current high-performance distributed systems employ switch-based interconnection networks. In this scenario, after the occurrence of a topological change, a management mechanism must reestablish connectivity between network devices. This requires performing a network reconfiguration, which consists in updating the routing function. The main challenge involved in network reconfiguration is the reduction of performance degradation during the change assimilation process. As shown in the performance evaluation section, former reconfiguration techniques significantly reduce network service since the application traffic is temporally stopped in order to avoid deadlocks. In addition, current solutions are only designed for networks that use distributed routing. In this paper, we propose and evaluate a first reconfiguration method for source routing networks that does not restrict the injection of packets during the change assimilation process. Without requiring additional network resources, our scheme is able to recover topology connectivity maintaining network throughput.

Some sensor network applications involve an aerial deployment of many sensor nodes over a particular area of interest. In this context, current range-free localization proposals, based on an iterative refinement and exchange of node estimations, are not directly applicable, because they introduce a high traffic overhead. In this paper, we propose to control this overhead by means of avoiding the transmission of certain localization packets. The criterion applied by this new localization technique to filter packets is based on the amount of improvement shown after updating an estimation and the time from the last transmission. We also tune this filter in order to find an optimal trade-off between the benefit in traffic and the penalty in time.

Overlapping Reconfiguration is currently the most efficient method to reconfigure an interconnection network, but is only valid for systems that apply distributed routing. This paper proposes a solution which enables utilization of Overlapping Reconfiguration in a source routed environment. We demonstrate how a synchronized injection of tokens has a significant impact on the performance of the method. Furthermore, we propose and evaluate an optimization of the original algorithm that reduces (and in some cases even eliminates) performance issues caused by the token forwarding regime, such as increased latency and decreased throughput.

This paper presents the simulation environment for the EIDOS (EquIpment Destined for Orientation and Safety) architecture applied to wildfire fighting operations. The development of this environment involves a multidisciplinary study, in which we have to handle several different types of information (geographical data, vegetation models, fire models, etc.) and devices (sensors, aerial vehicles, and mobile devices). Therefore, the simulation tool is actually composed of several independent and interconnected modules.

Recent years, computer performance has been significantly increased. As a consequence, data I/O systems have become bottlenecks within systems. In order to alleviate this problem, Advanced Switching Interconnect was proposed as a new standard for future high-performance interconnects. The Advanced Switching specification establishes a fabric management infrastructure, which is in charge of maintaining the connectivity between fabric endpoints after fabric initialization and each time a topological change takes place. Once the change has been detected, a fabric manager must discover the new topology, obtain a new set of valid fabric paths, and distribute them to the fabric endpoints. This paper evaluates a first implementation for this management mechanism, by analyzing the influence of application traffic on its performance, and the way in which network service can be affected by the change assimilation process.

Advanced switching is a new high-speed industrial standard serial interconnect. It is defined as a switching fabric architecture based on the PCI express technology. The advanced switching specification establishes a management infrastructure which maintains the fabric operation. The topology discovery process is triggered after fabric initialization and every time a topological change is detected. The information gathered by this process is used to build a set of paths between fabric endpoints. This work analyzes the performance of several possible implementations for this management task.

The advanced switching technology is a new high-performance standard serial inter-connect. Its specification establishes a management infrastructure in charge of maintaining the fabric operation after the occurrence of a topological change. When the change is detected, the management mechanism discovers the new topology, obtains a set of fabric paths, and finally distributes them to the endpoints. The main contribution of this paper is a completely functional mechanism that implements all these management tasks involved in handling topological changes in source routing switched networks, as advanced switching. We also analyze the behavior of this first proposal, in order to identify its bottlenecks and define future improvements.

InfiniBand is a high-performance switched network. Its topology may change due to devices being turned on/off, hot expansion, link remapping, and component failures. The InfiniBand specification defines a management infrastructure which is responsible for detecting and assimilating any change in the network. When a change occurs, management entities must update switch forwarding tables, in order to maintain the connectivity among end nodes. This implies the acquisition of the current topology and the computation of a new set of routes accordingly. It is desirable that the execution of this process does not affect the performance of the upper-level applications that are using the network. In previous works, we have proposed enhanced implementations for the main tasks involved in the assimilation of a change. Now, we present a detailed performance evaluation of a management mechanism which incorporates all our proposals

The InfiniBand architecture has been proposed as a technology both for communication between processing nodes and I/O devices, and for interprocessor communication. Its specification defines a basic management infrastructure that is responsible for subnet configuration and fault tolerance. Each time a topology change is detected, new forwarding tables have to be computed and uploaded to devices. The time required to compute these tables is a critical issue, due to application traffic is negatively affected by the temporary lack of connectivity. In this paper, we show the way to integrate several routing algorithms, in order to combine their advantages. In particular, we merge a new proposal, characterized by its high computation speed but low efficiency, with a traditional one, slower but more efficient. Our goal is to provide new routes in a short period of time, minimizing the degradation mentioned before, and maintaining, at the same time, high network performance.

Summary form only given. The InfiniBand architecture has been proposed as a technology both for communication between processing nodes and I/O devices, and for interprocessor communication. The InfiniBand specification defines a basic management infrastructure that is responsible for subnet configuration, activation, and fault tolerance. Each time a topology change is detected, management entities collect the current subnet topology. After that, new forwarding tables have to be computed and uploaded to routing devices. The time required to compute these tables is a critical issue, due to application traffic being negatively affected by the temporary lack of connectivity. We present a way to compute a valid set of subnet routes in a short period of time. These provisional routes can be immediately distributed to routing devices. After that, final routes can be later uploaded without affecting user traffic.

InfiniBand is becoming an industry standard both for communication between processing nodes and I/O devices, and for interprocessor communication. Instead of using a shared bus, InfiniBand employs an arbitrary (possibly irregular) switched point-to-point network. InfiniBand specification defines a basic management infrastructure that is responsible for subnet configuration, activation, and fault tolerance. After the detection of a topology change, management entities collect the current subnet topology. The topology discovery algorithm is one of the management issues that are outside the scope of the current specification. Preliminary implementations obtain the entire topological information each time a change is detected. In this work, we present and analyze an optimized implementation, based on exploring only the region that has been affected by the change.

The InfiniBand architecture is a high-performance network technology for the interconnection of processor nodes and I/O devices using a point-to-point switch-based fabric. The InfiniBand specification defines a basic management infrastructure that is responsible for subnet configuration, activation, and fault tolerance. Subnet management entities and functions are described, but the specifications do not impose any particular implementation. We present and analyze a complete subnet management mechanism for this architecture. We allow to anticipate future directions to obtain efficient management protocols

Switched point-to-point interconnection networks provide the high bandwidth and low latency required by current distributed applications. When the topology changes, a reconfiguration of the routing tables is performed to maintain network connectivity. In order to prevent deadlock, traditional reconfiguration schemes discard application traffic during the reconfiguration process. The consequence is that the network cannot provide the bandwidth demanded by user applications. In order to solve this problem, we proposed two deadlock-free schemes that allow traffic through the network while the reconfiguration is being performed By using these schemes, the network is able to fulfill the applications requirements. In this paper, we evaluate these traditional and novel reconfiguration schemes. In particular, we analyze the impact of network size and load on their behavior. Application traffic has been modeled by means of a self-similar pattern. Simulation results clearly show the large performance degradation associated with the traditional approach and the significant benefits that can be obtained by using dynamic reconfiguration techniques.

High-speed local area networks (LANs) consist of a set of switches interconnected by point-to-point links, and hosts linked to those switches through a network interface card. High-speed LANs may change their topology due to switches being turned on/off, hot expansion, link remapping, and component failures. In these cases, a distributed reconfiguration protocol analyzes the topology, computes the new routing tables, and downloads them to the corresponding switches. Unfortunately, in most cases, user traffic is stopped during the reconfiguration process to avoid deadlock. These strategies are called static reconfiguration techniques. Although network reconfigurations are not frequent, static reconfiguration such as this may take hundreds of milliseconds to execute, thus degrading system availability significantly. Several distributed real-time applications have strict communication requirements; Distributed multimedia applications have similar, although less strict, quality of service (QoS) requirements. Both stopping packet transmission and discarding packets due to the reconfiguration process prevent the system from satisfying the above requirements. Therefore, in order to support hard real-time and distributed multimedia applications over a high-speed LAN, we need to avoid stopping user traffic and discarding packets when the topology changes. In this paper, we propose a new deadlock-free distributed reconfiguration protocol that is able to asynchronously update routing tables without stopping user traffic. This protocol is valid for any topology, including regular as well as irregular topologies. It is also valid for packet switching as well as for cut-through switching techniques and does not rely on the existence of virtual channels to work. Simulation results show that the behavior of our protocol is significantly better than for other protocols based on stopping user traffic.

High-speed local area networks (LANs) consist of a set of switches connected by point-to-point links, and hosts linked to switches through a network interface card. High-speed LANs may change their topology due to switches and hosts being turned on/off, link remapping, and component failures. In these cases, a distributed reconfiguration algorithm analyzes the topology, computes the new routing tables, and downloads them to the corresponding switches. Unfortunately, in most cases, user traffic is stopped during the reconfiguration process to avoid deadlock. Although network reconfigurations are not frequent, static reconfiguration such as this may take hundreds of milliseconds to execute, thus degrading system availability significantly. In this paper, we propose a new deadlock-free distributed reconfiguration algorithm that is able to asynchronously update routing tables without stopping user traffic. This algorithm is valid for any topology, including regular as well as irregular topologies. Simulation results show that the behavior of our algorithm is significantly better than for other algorithms based on a spanning-tree formation.