This paper provides an overview of extremelyinteractive and low latency immersive services as well as on the relevant industry and standardization activities. Immersive services immerse a viewer or the viewed digital objects into an environment that is either real, virtual or a mixture of both. The applications are accordingly named as Virtual Reality, Augmented Reality, Extended Reality, and Holography applications. These applications benefit from the ongoing advances in user interfaces, computing technologies, and networking technologies. Such applications are expected to generate most of the traffic in the next generation networks, particularly 6G networks. In this paper, the main relevant use cases are introduced along with their respective requirements. The paper also provides insights on the relevant architectures and solutions, and highlights some research challenges and directions.

The management of remote services, such as remote surgery, remote sensing, or remote driving, has become increasingly important, especially with the emerging 5G and Beyond 5G technologies. However, the strict network requirements of these remote services represent one of the major challenges that hinder their fast and large-scale deployment in critical infrastructures. This article addresses certain issues inherent in remote and immersive control of virtual reality (VR)-based unmanned aerial vehicles (UAVs), whereby a user remotely controls UAVs, equipped with 360 • cameras, using their head-mounted devices (HMD) and their respective controllers. Remote and immersive control services, using 360 • video streams, require much lower latency and higher throughput for true immersion and high service reliability. To assess and analyze these requirements, this article introduces a real-life testbed system that leverages different technologies (e.g., VR, 360 • video streaming over 4G/5G, and edge computing). In the performance evaluation, different latency types are considered. They are namely: 1) glass-to-glass latency between the 360 • camera of a remote UAV and the HMD display; 2) user/pilot's reaction latency; and 3) the command/execution latency. The obtained results indicate that the responsiveness (dubbed Glass-to-Reaction-to-Execution-GRElatency) of a pilot, using our system, to a sudden event is within an acceptable range, i.e., around 900 ms.

5G and beyond mobile systems target a plethora of emerging industrial and entertainment verticals that incur extra overhead to the network. These verticals are characterized by vigorous, continuous, and conflicting requirements that make the desired system's mission strenuous and more challenging. These verticals, such as autonomous driving, will accommodate immersive services, including virtual reality/augmented reality (VR/AR) and Holography services. Immersive services, in particular, have strict requirements for latency, throughput, and positioning. This paper discusses VR-based remote services' potential, which occupies an important place among immersive services such as remote surgery, remote space control, and remote driving of Unmanned Aerial Vehicles (UAVs) or cars. Such services require an ultra-low Glass-to-Glass latency to avoid any failure and accidents when remotely controlling devices. We evaluate an immersive remote control service from the end-to-end communication perspectives using different camera devices that stream real-time 360 • videos to a VR Head Mounted Device (HMD). The obtained results demonstrate the challenges of such service and the need for more advanced and optimized techniques, devices, and protocols to achieve less than 20 ms of Glass-to-Glass latency.

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