Escalonamento multicanal para convergecast em redes TSCH

Abstract

This dissertation presents a multichannel algorithm for convergecast developed in the context of Industrial Wireless Sensor Networks. It calculates a convergence tree and a schedule for sending and receiving messages in Time Slotted Channel Hopping (TSCH) networks. To build the convergence tree, there is a prior creation of local trees. The Routing Protocol for Low-Power and Lossy Network (RPL) was used in the attribution of ranks and in the process of connecting the nodes with the formation of a global tree. The algorithm works with the creation of a collision-free schedule, due to the use of a technique called Dilution. This is based on the fact that one or more nodes in relative positions of a plane can transmit messages in the same time interval without interference or loss of messages. The entire algorithm was developed under a real protocol stack that runs under the Cooja simulator contained in the Contiki-NG operating system. The simulator implements the Unit Disk Graph Medium (UDGM) interference model adopted in this work. It allows sensor nodes to communicate over a given transmission range r, which is modeled as an ideal disk. As the Contiki-NG operating system offers reference implementations of the TSCH, it was decided to compare algorithms from that system with the one proposed in this dissertation. The implemented algorithm can generate schedules with a reduced slotframe size, even with a large number of sensor nodes in the network. Satisfactory results were also presented regarding the packet delivery rate and average delay time in the communication of the created convergecasts, surpassing some approaches that deal with the same metrics.