# DTN Trustworthiness for Permafrost Telemetry IoT Network
###### Abstract  
The SHETLAND-NET research project aims to build an Internet of Things (IoT) telemetry service in Antarctica to automatize the data collection of permafrost research studies on interconnecting remote wireless sensor networks (WSNs) through near vertical incidence skywave (NVIS) long fat networks (LFN). The proposed architecture presents some properties from challenging networks that require the use of delay tolerant networking (DTN) opportunistic techniques that send the collected data during the night as a bulk data transfer whenever a link comes available. This process might result in network congestion and packet loss. This is a complex architecture that demands a thorough assessment of the solution's viability and an analysis of the transport protocols in order to find the option which best suits the use case to achieve superior trustworthiness in network congestion situations. A heterogeneous layer-based model is used to measure and improve the trustworthiness of the service. The scenario and different transport protocols are modeled to be compared, and the system's trustworthiness is assessed through simulations. transport protocols; trustworthiness; Antarctica; IoT; NVIS; remote WSN; LFN 2021 24 September 20  
Therefore, before the deployment phase of our project, we had to study and try to anticipate the expected trustworthiness of the IoT telemetry service we want to deploy. For this reason, we defined a model to assess the trustworthiness of our proposed system [7]. This enabled us to foresee the possible trustworthiness issues that might arise during the campaign in the field and decide on the respective countermeasures. For our work, we focus on the use case of automating the monitoring of Ground Terrestrial Network-Permafrost (GTN-P) stations [9], which are used in permafrost research studies. Each of these GTN-P stations senses 32 different values hourly, which need to be remotely monitored from a control center. During the Antarctic campaign, we will deploy a test scenario. WSNs will be placed in two locations: the Spanish Juan Carlos I Base in Livingston Island, and the Uruguayan Artigas Base in King George Island, both part of the South Shetland Islands. The Artigas Base will provide Internet connectivity, so data gathered from the WSNs can be reached remotely. However, sensors in the Juan Carlos I Base will not have direct Internet connectivity, and the data from these sensors will need to be sent through an NVIS link to the Artigas base in order to reach the Internet. Figure 1 shows the test scenario in Antarctica. As seen in previous research [4], the main drawback of the NVIS link is its unavailability during the night, given that the ionosphere's characteristics vary drastically due to solar activity. For this reason, we decided to adopt a delay tolerant network (DTN) technique to opportunistically send all the data collected during the night as a bulk data transfer when the NVIS link becomes available in the morning. This complex scenario required a trustworthiness assessment to analyze its feasibility to be deployed in Antarctica before the campaign [7]. As shown in our first round of simulations, performing this opportunistic bulk data transfer in an LFN that presents network challenges could degrade the system's performance (packet losses) due to network congestion caused by the large quantity of data sent. On the other hand, in prior work, we also analyzed the suitability of different transport protocols for LFNs and designed a new one, the Enhanced Adaptive and Aggressive Transport Protocol [5; 11]. Given that the NVIS links can also be considered as LFNs  
Figure 1: Map of the South Shetland Islands in Antarctica [10], showing the position of the WSNs (blue circles) during the test scenario of the campaign. The NVIS link is represented with the discontinuous blue line, and the Internet connectivity is represented with the discontinuous red line. The reproduction of the image was slightly modified under a Creative Commons License (CC BY-SA 3.0).