Drone Base Station Trajectory Management for Optimal Scheduling in LTE-Based Sparse Delay-Sensitive M2M Networks

Providing connectivity in areas out of reach of the cellular infrastructure is a very active area of research. This connectivity is particularly needed in case of the deployment of machine type communication devices (MTCDs) for critical purposes such as homeland security. In such applications, MTCDs are deployed in areas that are hard to reach using regular communications infrastructure while the collected data is timely critical. Drone-supported communications constitute a new trend in complementing the reach of the terrestrial communication infrastructure. In this study, drones are used as base stations to provide real-time communication services to gather critical data out of a group of MTCDs that are sparsely deployed in a marine environment. Studying different communication technologies as LTE, WiFi, LPWAN and Free-Space Optical communication (FSOC) incorporated with the drone communications was important in the first phase of this research to identify the best candidate for addressing this need. We have determined the cellular technology, and particularly LTE, to be the most suitable candidate to support such applications. In this case, an LTE base station would be mounted on the drone which will help communicate with the different MTCDs to transmit their data to the network backhaul. We then formulate the problem model mathematically and devise the trajectory planning and scheduling algorithm that decides the drone path and the resulting scheduling. Based on this formulation, we decided to compare between an Ant Colony Optimization (ACO) based technique that optimizes the drone movement among the sparsely-deployed MTCDs and a Genetic Algorithm (GA) based solution that achieves the same purpose. This optimization is based on minimizing the energy cost of the drone movement while ensuring the data transmission deadline missing is minimized. We present the results of several simulation experiments that validate the different performance aspects of the technique

Análise de desempenho de junção à rede via OTAA e uso de ciclo útil em redes LoRaWAN

Wireless networks with demands for coverage over long distances and low power are became more requested and used in several applications. Among these technologies, one of the most promising is the LoRa technology, together with the LoRaWAN protocol. However, so many internal parameters and external factors may be influencing the network performance, including the device’s joining procedure at the LoRaWAN network. Furthermore, for high density networks, the adoption of duty cycle limits are essential for a good operation. In order to mitigate this problem, three different strategies for duty cycle usage during transmissions of join request frames are proposed: exponential, linear and constant. Additionally, will be presented two additional strategies to improve the performance of join procedure, with the use of adaptative data rate and an adaptative random margin for duty cycle periods. For validation of the methods, internal and external network parameters will be evaluated, in order to assess the performance impact of the proposals, analyzed through experimental results, using real devices with focus on the join procedure.CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorDissertação (Mestrado)Redes de comunicação sem fio com demandas por cobertura em longas distâncias e baixo consumo energético vem se tornando cada vez mais requisitadas e utilizadas em diversas aplicações. Dentre essas tecnologias, umas das mais promissoras é a tecnologia LoRa, juntamente com o protocolo LoRaWAN. No entanto, inúmeros parâmetros internos e fatores externos podem influenciar no desempenho da rede, incluindo no processo de associação dos dispositivos à rede LoRaWAN. Além disso, para redes com alta densidade de dispositivos, a adoção de limitações pelo uso do ciclo útil é essencial para seu bom funcionamento. Com o objetivo de mitigar esse problema, neste trabalho são propostas três estratégias diferentes para o uso do ciclo útil nas transmissões de quadros de junção à rede, ou join request, a saber: exponencial, linear e constante. Adicionalmente, também serão apresentadas mais duas propostas para melhoria no desempenho do processo de associação, com o uso de uma taxa de dados, ou data rate, adaptativo e a margem aleatória adaptativa do período do ciclo útil. Para validar os métodos serão alterados alguns parâmetros internos e externos da rede afim de avaliar o impacto das propostas quanto ao desempenho, analisados através de resultados experimentais, utilizando dispositivos reais e com foco no processo de associação à rede