Towards the Internet of X-things: New Possibilities for Underwater, Underground, and Outer Space Exploration

The rapid growth of the world's population demands more natural resources, , and space. World-renowned physicist Stephan Hawking has argued that soon will require another world to live on because we are running out of space natural resources. This ever-increasing demand for resources and space novel technologies to explore natural resources, produce more crops, and outer space. Internet of X-things (X-IoT) is an enabling technology to all of the above issues. In this article, we have presented an of a unified framework of X-IoT. The framework of X-IoT consists of major categories. The first one is the Internet of underwater things (IoUT) for smart oceans. The second category is the Internet of underground (IoUGT) for smart agriculture, seismic monitoring, and Oil/Gas fields. third category is the Internet of space things (IoST) for outer space, to provide global coverage, and to enable inter-satellite. Through this framework, we get to know what has been done since and how the technical challenges across the broad spectrum of emerging cases under the water, underground and over the space are converging toward solutions.