Proposal and evaluation of network size estimation mechanisms for media access protocols in satellite IoT

Abstract

This work presents the proposal and evaluation of network size estimation mechanisms for media access protocols in a satellite IoT scenario. The study scenario is a wireless network of sensors deployed on the Earth's surface that communicates directly with a low-cost nanosatellite CubeSat as it moves through its orbit around the Earth. The CubeSat standard is presented as a low-cost tool to overcome the economic barriers that prevent several countries from accessing satellite technology. The latter is of great importance given emerging technologies such as the Internet of Things (IoT), which is anticipated as a significant impact that will require the operation of a large number of interconnected devices. Most of these devices are sensor nodes deployed on the face of the Earth, often in remote areas devoid of signal for which satellite coverage plays an important role. However, the limitations of a low-cost satellite are considerable, and the communication channel's management becomes difficult as the number of nodes that share the channel increases, mainly because the satellite does not know this number. The ignorance of the size of the sensor network deployed in a given area leads to several problems such as unattended nodes, loss of valuable information, and increased costs in implementing wireless networks. Since there is no specific solution in the literature for this scenario, this work proposes the design of a sensor network size estimator and the adaptation of an existing mechanism for this particular case. Secondly, these estimators are validated by simulations of a medium access control (MAC) protocol implementing them and improving network performance. The work culminates in the successful design and adaptation of two network size estimation mechanisms that allow feedback to the Frame Slotted Aloha (FSA) communication protocol to maintain approximately constant throughput up to a number of 2000 nodes within the satellite footprint. Finally, the design of a mechanism that ensures fairness between the nodes is proposed as future work, supplying geographic disadvantages.