Sensing and Communication
Wireless sensing technologies aim at acquiring information about a remote object or environment and its characteristics without physically contacting it. The perception data of the object and its surrounding can be utilized for analysis, so that meaningful information about the object or environment and its characteristics can be obtained.5G Wireless sensing is a technology enabler to acquire information about characteristics of the environment and/or objects within the environment, that uses radio waves to determine the distance (range), angle, or instantaneous linear velocity of objects (shape, size, orientation, speed, location, distances or relative motion between objects). The 5G wireless sensing service relies on analyzing the transmissions, reflections, and scattering of wireless sensing signals.5G system sensing services target different verticals/applications, e.g. autonomous/assisted driving, V2X, UAVs, 3D map reconstruction, smart city, smart home, factories, healthcare, maritime sector:
- object and intruder detection for smart home, on a highway, for railways, for factory, for predefined secure areas around critical infrastructure
- collision avoidance and trajectory tracking of UAVs, vehicles, AGVs
- automotive maneuvering and navigation
- public safety search and rescue
- rainfall monitoring and flooding
- health and sports monitoring
Integrated sensing and communications (ISAC)Sensing (detection, estimation, recognition) collects and extracts information from noisy observations, while communication (efficiency, reliability) focuses on transferring information via specifically tailored signals and then recovering it from a noisy environment. The ultimate goal of ISAC is to unify these two operations and to pursue direct tradeoffs between them as well as mutual performance gains. On the one hand, ISAC is expected to considerably improve spectral and energy efficiencies, while reducing both hardware and signaling costs, since it attempts to merge sensing and communication into a single system, which previously competed over various types of resources. On the other hand, ISAC also pursues a deeper integration paradigm where the two functionalities are no longer viewed as separate end-goals but are co-designed for mutual benefits, i.e., via communication-assisted sensing and sensing-assisted communication.In the earliest ISAC implementation (1960s), communication information was embedded into a group of radar pulses, where the radar was used as range instrumentation. Thera are clear opportunity for the convergence of the two technologies into systems and devices, that can serve sensing and communications with a single transmission. Research on radar and communication began to merge in the early 1990s-2000s. Given the above technical trends, the wireless community is now witnessing a new paradigm shift that may shape our modern information society in profound ways. While wireless sensors are already ubiquitous, they are expected to be further integrated into wireless networks in the future.With the use of ISAC technologies, the role of existing cellular networks will shift to a ubiquitously deployed large-scale sensor network, namely a perceptive network, which will trigger a variety of novel applications for the current communication industry. We provide some examples below:
- sensing as a service (enhanced localization and tracking, area imaging, drone monitoring and management)
- Smart Home and in-cabin sensing (human activity recognition, spatial-aware computing)
- Vehicle to Everything (V2X) (vehicle platooning, simultaneous localization and mapping - SLAM)
- Smart Manufacturing and Industrial IoT
- remote sensing and geoscience
- environmental monitoring
- human computer interaction (HCI)
Collaborative sensing in Perceptive mobile networksWith the development of innovative applications that demand accurate environment information, e.g., autonomous driving, sensing becomes an important requirement for future wireless networks. To this end, integrated sensing and communication (ISAC) provides a promising platform to exploit the synergy between sensing and communication, where perceptive mobile networks (PMNs) were proposed to add accurate sensing capability to existing wireless networks. The well-developed cellular networks offer exciting opportunities for sensing, including large coverage, strong computation and communication power, and most importantly networked sensing, where the perspectives from multiple sensing nodes can be collaboratively utilized for sensing the same target. However, PMNs also face big challenges such as the inherent interference between sensing and communication, the complex sensing environment, and the tracking of high-speed targets by cellular networks.Perceptive mobile networks (PMNs) are a special type of ISAC system that focuses on adding sensing capability to the cellular networksAfter several generations of development, wireless communications has evolved from a system with only communication services to an intelligent network that not only moves data but also performs edge-computing and distributed learning/inference tasks. The advancement of innovative applications such as autonomous driving and environment monitoring further requires accurate sensing capability from future wireless networks. To this end, the recently proposed integrated sensing and communication (ISAC) framework offers a promising way to integrate sensing and communication with possible hardware and software reuse, especially after millimeter wave (mmWave) was adopted for 5G and beyond systems. There are many favorable properties of cellular networks that can facilitate sensing.
- First, the well-developed mobile network with high-density base stations (BSs) can provide large sensing coverage. The high-density nodes are very important because mmWave experiences severe pathloss and is thus not suitable for long-range sensing tasks.
- Second, the large number of distributed and connected sensing nodes enables networked sensing, where multiple perspectives from different sensing nodes can be exploited to sense the same target.
- Finally, the strong computation and communication power of PMNs create a good platform for large-scale environment estimation and mapping, which will not only benefit sensing but also enhance communication in terms of channel estimation, resource allocation, beam tracking, and more.
Convergence of the digital and the physical worldWireless systems beyond 5G evolve towards embracing both sensing and communication, resulting in increased convergence of the digital and the physical world. The existence of fused digital-physical realms raises critical questions regarding temporal ordering, causality, and the synchronization of events. With the growing reliance on real-time interactions and applications such as digital twins, extended reality, and the metaverse, the need for temporal forensics becomes crucial. The physical time has its order and arrow, such that its manipulation is still in the domain of science fiction. Nevertheless, the perception of time in digital interconnected systems is dependent on the way information is processed and transported. Our reality becomes increasingly a fusion of physical and digital worlds, which brings in the central question of perception of time and ordering of events.
