Abstract
Every year, the number of ubiquitous sensor networks (USN) is increasing and the need for remote USN communications is emerging in some scenarios. As an alternative to satellite communications, more interests are focused on high frequencies (HF) communications as a low-cost option to reach links of more than 250 km without a line of sight. The HF standards are designed for generic communication channels being not robust for near vertical incidence skywave (NVIS) USN. In this article, we propose a new protocol for USN in remote places based on NVIS communications. For that purpose, we study the main characteristics of the NVIS channel with the presence of groundwaves, particularly in Antarctica. We analyze the availability of the channel, the height of the layers, the delay spread, and the Doppler spread. On the basis of the results obtained, we propose two protocols based on an OFDM (orthogonal frequency division multiplexing) modulation depending on the presence of the groundwave at the receiver. Finally, we make a simulation of the two OFDM configurations and we compare it with real tested standard modulations. The results show a better performance of the new protocol compared to the current HF standards.
Highlights
Nowadays the number of connected devices as ubiquitous sensor networks (USN) has increased significantly compared to previous years
The results show a better performance of the new protocol compared to the current high frequencies (HF) standards
We study the main characteristics of the near vertical incidence skywave (NVIS) channel for high latitudes, in Antarctica
Summary
Nowadays the number of connected devices as ubiquitous sensor networks (USN) has increased significantly compared to previous years. The number of Internet of Things (IoT) devices connected in 2019 was about 26.66 billion and is expected to increase up to 75.44 billion of devices at 2025 [1]. This fact is directly related to the appearance of new technologies and frame protocols to connect those devices according to their needs. Sigfox [2] and LoRa. Alliance [3] have defined new frame protocols and frequency usage to maximize the connectivity distance and the number of devices connected to one node. Wize Alliance [4] defined the frequency usage to achieve a high penetration on walls to assure the connectivity in meters rooms or basements
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