# Emerging Topics in Joint Radio-Based Positioning, Sensing, and Communications
## 1 Introduction and Definitions  
There is a continuously increasing demand for more efficient, cost-effective, and high-performance wireless systems with wide areas of application, including, for example, telecommunications, maritime, air and land transportation, environmental monitoring, e-health, defense, and industrial applications. By integrating or offering joint solutions for wireless positioning, sensing, and communications, one can unlock new possibilities and drive innovation in multiple fields and businesses. **Wireless positioning** refers to the process of determining the location of a device or object using wireless or Radio Frequency (RF) or, simply, radio signals. This concept is closely related to the concepts of wireless tracking (i.e., monitoring and tracking the location and movement of objects, people, or animals in time) and navigation (i.e., determining or guiding the movement of a device, person, or animal from one location to another). **Wireless sensing** refers typically to two aspects: determining the presence of an object, person, or animal in a certain space-time dimension and locating or mapping the surroundings (objects, devices, cars, persons, etc.) by employing radio signals. When the wireless sensing focuses on detecting the distances to surrounding objects and their velocities, it is also known as radar technology. **Wireless communications** refer to the transmission of data or information between devices through RF signals, without the use of physical connections such as wires or cables. Both cellular systems such as Fourth generation of cellular networks (4G), Fifth generation of cellular networks (5G), or Sixth generation of cellular networks (6G)and non-cellular systems (e.g., satellite-based communications, Internet of Things (IoT)-based communications, WiFi, etc.) are covered by the broad terminology of wireless or radio-based communications. Traditionally, these three areas (positioning, sensing, and communications) have been addressed separately by different research communities, such as the navigation community, the radar or sensing community, and the wireless communication community. For example, the _navigation community_ has focused on various location technologies to support the indoor, outdoor, and seamless outdoor-to-indoor positioning, including both RF and non-RF signals, such as Global Navigation Satellite Systems (GNSS), [1; 2], Low Earth Orbit (LEO), Positioning, navigation, and Timing (PNT) [3; 4], cellular 4G/5G/6G signals [5; 6; 7], inertial sensors [8; 9], magnetic signals [10], vision or sound signals [8; 11], etc. ; comprehensive surveys on wireless positioning from the past five years can be found, for example, in [12; 13; 14]. The _radar or sensing community_ has been traditionally focused on techniques for improving the detection, estimation, and classification of targets, with applications mainly targeting vehicular and autonomous systems, remote sensing, environmental monitoring, and surveillance, as well as for collision avoidance. Recent surveys in the field of wireless sensing can be found in [15; 16; 17]. In a broader interpretation, wireless positioning can be seen as a part of the term wireless sensing, wherein the sensing terminology refers to sensing and locating everything in the environment, including the devices of interest. Last but not least, the _wireless communication community_ has focused on very broad areas, encompassing terrestrial (underwater, air, maritime, railroad,...) and non-terrestrial/space communications and covering everything communications-related from the physical layer to application layers and from model-based statistical approaches to Machine Learning (ML)/ Artificial Intelligence (AI)-based approaches. A few examples of surveys pertinent to top research topics involving wireless communication over the past five years are: Ref. [18] (virtualization in future wireless communications), Ref. [19] (ML/federated learning use in future wireless communications), Ref.