Spectrum Sharing between UAV-based Wireless Mesh Networks and Ground Networks

The unmanned aerial vehicle (UAV)-based wireless mesh networks can economically provide wireless services for the areas with disasters. However, the capacity of air-to-air communications is limited due to the multi-hop transmissions. In this paper, the spectrum sharing between UAV-based wireless mesh networks and ground networks is studied to improve the capacity of the UAV networks. Considering the distribution of UAVs as a three-dimensional (3D) homogeneous Poisson point process (PPP) within a vertical range, the stochastic geometry is applied to analyze the impact of the height of UAVs, the transmit power of UAVs, the density of UAVs and the vertical range, etc., on the coverage probability of ground network user and UAV network user, respectively. The optimal height of UAVs is numerically achieved in maximizing the capacity of UAV networks with the constraint of the coverage probability of ground network user. This paper provides a basic guideline for the deployment of UAV-based wireless mesh networks.Comment: 6 pages, 6 figure

Design and Comparative Study Among Antennas of GCS for Telemetry Communication System of UAV

Recently, Unmanned Aerial Vehicle (UAV) becomes a popular and interesting technology for researchers and academics because it has high potential to be implemented in various fields. The UAV operation is managed by a Ground Control Station (GCS) on which requires a communication system to send control signals and acquire data collected by sensors on UAV. The longer the UAV's flying distance needs a higher transmission power budget that can be achieved by increasing transmitter power, increasing receiver sensitivity, or increasing antenna gain. However, the design of communications systems on a flying platform is limited by the following constraints. The transmitter, receiver, and antenna must be compact, lightweight, and energy-efficient to save battery on the vehicle. Although the antenna does not directly influence the energy consumption from the battery, an increase in antenna gain usually requires an increase of the antenna dimension that causes higher weight and or reduces the aerodynamics. Therefore, the most efficient way to increase the link budget is by modifying the antenna on the GCS. This paper describes the analysis of antennas commonly used in GCSs for UAV communication links, namely the Yagi-Uda, bi-quad, and double bi-quad antennas. The antenna is designed to work at a frequency of 433.5 MHz following the transceiver device used. The antenna designs are numerically simulated then fabricated for evaluating their performance. The testing is done on the following issues, i.e. the antenna's basic parameters measurement, the ground-to-ground transmission test, and the ground to air transmission test. The test results show that the double bi-quad gives better performance than the other two other testing antennas

An Experimental Analysis on Drone-Mounted Access Points for Improved Latency-Reliability

The anticipated densification of contemporary communications infrastructure expects the use of drone small cells (DSCs). Thus, we experimentally evaluate the capability of providing local and personalized coverage with a drone mounted Wi-Fi access point that uses the nearby LTE infrastructure as a backhaul in areas with mixed line of sight(LoS) and Non-LoS (NLoS) links to the local cellular infrastructure. To assess the potential of DSCs for reliable and low latency communication of outdoor users, we measure the channel quality and the total round trip latency of the system. For a drone following the ground user, the DSC-provided network extends the coverage for an extra 6.4% when compared to the classical LTE-direct link. Moreover, the DSC setup provides latencies that are consistently smaller than 50 msfor 95% of the experiment. Within the coverage of the LTE-direct connection, we observed a latency ceiling of 120ms for 95% reliability of the LTE-direct connection. The highest latency observed for the DSC system was 1200ms, while the LTE-direct link never exceeded 500 ms. As such, DSC setups are not only essential in NLoS situations, but consistently improve the latency of users in outdoor scenarios.Comment: To be published in proceedings of DroNet21. Winner of DroNet21's Best Paper Awar

Connecting Disjoint Nodes Through a UAV-Based Wireless Network for Bridging Communication Using IEEE 802.11 Protocols

Cooperative aerial wireless networks composed of small unmanned aerial vehicles(UAVs) are easy and fast to deploy and provide on the fly communication facilities in situations where part of the communication infrastructure is destroyed and the survivors need to be rescued on emergency basis. In this article, we worked on such a cooperative aerial UAV-based wireless network to connect the two participating stations. The proposed method provides on the fly communication facilities to connect the two ground stations through a wireless access point (AP) mounted on a UAV using the IEEE 802.11a/b/g/n. We conducted our experiments both indoor and outdoor to investigate the performance of IEEE 802.11 protocol stack including a/b/g/n. We envisioned two different cases: line of sight (LoS) and non-line of sight (NLoS). In LoS, we consider three different scenarios with respect to UAV altitude and performed the experiments at different altitudes to measure the performance and applicability of the proposed system in catastrophic situations and healthcare applications. Similarly, for NLoS, we performed a single set of experiments in an indoor environment. Based on our observations from the experiments, 802.11n at 2.4 GHz outperforms the other IEEE protocols in terms of data rate followed by 802.11n at 5 GHz band. We also concluded that 802.11n is the more suitable protocol that can be practiced in disastrous situations such as rescue operations and healthcare applications

Mejora del sistema de comunicación mediante el uso de una antena microstrip aplicado a los sistemas aéreos no tripulados

El presente proyecto de tesis consiste en el desarrollo de un sistema de comunicación mediante el uso de una antena microstrip en los sistemas aéreos no tripulados. En el primer capítulo trata sobre la situación actual de los vehículos aéreos no tripulados (UAV) y sus aplicaciones. Además, se presentarán la justificación y las tecnologías existentes de los sistemas de comunicaciones y telemetría que son importantes para la comprensión del presente trabajo. En el segundo capítulo se describe teóricamente las partes del sistema de comunicación y los conceptos necesarios para entender el diseño del presente sistema enfocado en la antena a usar. En el tercer capítulo se describe el diseño del sistema completo de comunicación a partir de diagramas de bloques, elección de componentes y se muestra la forma y los métodos a partir de los cuales se obtiene el diseño funcional de la antena. Haciendo uso de software de simulación CST Studio se realiza la comprobación de los resultados teóricos de los dispositivos. Por último, se detalla el método usado en el presente proyecto para la fabricación de este tipo de antenas. En el último capítulo se caracteriza la antena a través de la medición del parámetro que la define; en este proyecto se realiza la medición del coeficiente de reflexión (parámetro S11), a su vez que se hace el correspondiente análisis en comparación con los resultados obtenidos mediante simulación en el capítulo 3. También se muestra las pruebas y los resultados obtenidos por el UAV con el sistema de comunicación integrado tanto en tierra como en aire. Por último, se muestran las conclusiones del análisis de los resultados obtenidos y recomendaciones a seguir.Tesi

An Information-Motivated Exploration Agent to Locate Stationary Persons with Wireless Transmitters in Unknown Environments

Unmanned Aerial Vehicles (UAVs) show promise in a variety of applications and recently were explored in the area of Search and Rescue (SAR) for finding victims. In this paper we consider the problem of finding multiple unknown stationary transmitters in a discrete simulated unknown environment, where the goal is to locate all transmitters in as short a time as possible. Existing solutions in the UAV search space typically search for a single target, assume a simple environment, assume target properties are known or have other unrealistic assumptions. We simulate large, complex environments with limited a priori information about the environment and transmitter properties. We propose a Bayesian search algorithm, Information Exploration Behaviour (IEB), that maximizes predicted information gain at each search step, incorporating information from multiple sensors whilst making minimal assumptions about the scenario. This search method is inspired by the information theory concept of empowerment. Our algorithm shows significant speed-up compared to baseline algorithms, being orders of magnitude faster than a random agent and 10 times faster than a lawnmower strategy, even in complex scenarios. The IEB agent is able to make use of received transmitter signals from unknown sources and incorporate both an exploration and search strategy

Caracterización de dispositivos Wi-Fi comerciales para su aplicación en comunicaciones entre UAVs y dispositivos de tierra

Los vehículos aéreos no tripulados (popularmente conocidos como drones) constituyen en la actualidad una tecnología emergente y con aplicaciones en múltiples campos. Este trabajo pretende construir un sistema de comunicaciones inalámbrico basado en el estándar Wi-Fi entre dos Raspberry Pi para su uso en estos dispositivos y medir su calidad. Antes de conseguir este objetivo será necesario cumplir varios hitos: 1. Preparar las Raspberry Pi para que se adapten a las exigencias del sistema de comunicaciones. 2. Considerar las opciones disponibles en el mercado para conseguir la comunicación inalámbrica. 3. Determinar qué características de las comunicaciones quieren medirse y aplicar las herramientas necesarias para ello. 4. Diseñar unos programas que consigan obtener, de las herramientas mencionadas en el punto anterior, los parámetros para definir la calidad de las comunicaciones. Una vez procesados los parámetros de calidad de las comunicaciones se podrá reflexionar acerca de las posibilidades de un sistema de comunicaciones inalámbrico basado en Raspberry Pi, y proponer aquellas aplicaciones que, de acuerdo con los datos obtenidos y los recursos manejados, resultaran más provechosas para su uso en UAVs.Unmanned aerial vehicles (popularly known as drones) are currently an emerging technology with applications in multiple fields. This paper aims to build a wireless communications system based on the Wi-Fi standard between two Raspberry Pi for their use in these devices and measure their quality. Before achieving this goal, several milestones should be met: Prepare the tools so they adapt to the demands of the communications system. Consider the options available in the market for wireless communication. Determine what characteristics of the communications want to be measured and apply the tools needed to do so. Design programs able to obtain, from the tools mentioned in the previous point, the parameters to define the quality of communications. Once the quality parameters of the communications are processed, it will be possible to reflect on the possibilities of a wireless communications system based on Raspberry Pi, and to propose those applications that, according to the data obtained and the resources handled, will be more profitable for its use in UAVs.Universidad de Sevilla. Grado en Ingeniería de las Tecnologías de Telecomunicació

Diseño u construcción de un prototipo de sistema de vuelo cooperativo de vehículos aéreos no tripulados para tareas de microfumigación.

Se diseñó y construyó un prototipo de sistema de vuelo cooperativo para vehículos aéreos no tripulados (VANTs) enfocado a aplicaciones de microfumigación. Está conformado por dos VANTs denominados inicial y terminal, los cuales cumplen con los requerimientos planteados. Para hacer posible el vuelo cooperativo un cuadrirrotor retransmite la comunicación por radio a otro cuadrirrotor. Una parte modular de la investigación fue hacer viable la retransmisión de comunicación, realizada por módulos comerciales de telemetría para el intercambio de información entre las aeronaves. Se utilizó técnicas de multiplexación por división de tiempo (TDM) y espectro expandido de salto de frecuencia (FHSS) para que la presencia de varias telemetrías no produjese interferencias de radio frecuencia. Para el control autónomo de la misión, de retransmisión y de tierra se desarrolló un conjunto de programas escritos en C++, además, de una interfaz de usuario realizada en C# para el envió de comandos y la supervisión de datos y estado del vuelo. Se realizaron 15 pruebas de vuelo en modo auto y la estación de control de tierra era capaz de manejar un solo VANT a la vez y la distancia recorrida en promedio fue de 665.4 metros. Con el prototipo de sistema de vuelo cooperativo se ejecutó el mismo número de ensayos, pero con la capacidad de usar 2 VANTs por lo cual el promedio de la distancia recorrida ascendió a 1349.33 metros. Se encontró una diferencia estadísticamente significativa en la distancia recorrida de las pruebas al realizar la prueba de t de Student por lo que se concluye que el prototipo es capaz de abarcar más terreno en el mismo tiempo haciéndolo muy óptimo. Se recomienda centralizar el intercambio de información en una plataforma tecnológica para el control multi VANT.The present investigation shows that a prototype cooperative flight system was designed and built for unmanned aerial vehicles (UAVs) focused on microfumigation applications. It is made up of the initial and terminal (UAVs), which comply with the requirements. Making cooperative flight possible, a drone radio communication to another drone. A modular part of the research was to make the retransmission of communication viable, carried out by commercial telemetry modules for the exchange of information between aircraft. Time division multiplexing (TDM) and frequency hopping expanded spectrum (FHSS) techniques were used, so that the presence of several telemetries did not produce radio frequency interference. For the autonomous control of the mission relay and ground, a set of programs written in C ++ was developed, in addition to a user interface made in C # for sending commands and monitoring data and flight status. Fifteen flight tests were conducted in auto mode, the ground control station was able to handle only one (UAVs) at a time and distance traveled on average was 665.4 meters. With the prototype cooperative flight system, it was executed the same number of trials, but with the ability to use two (UAVs) the average distance traveled amounted to 1349.33 meters. A statistically significant difference was found in the distance traveled from the tests when the Student t-test was carried out, so it is concluded that the prototype is capable of covering more ground in the same time, making it very optimal. It is recommended to centralize the exchange of information in a technological platform for multi-UAV control

Development and testing of a two-UAV communication relay system

2016-2017 > Academic research: refereed > Publication in refereed journal201804_a bcmaVersion of RecordSelf-fundedPublishe