**3.2. Cyber: physical system - enhancing cloud access**

The discussion presents a solution that enables subscribers to access cloud content when E1ð Þ *sz* ≤ *lth* . This scenario i.e. E1ð Þ *sz* ≤ *lth* describes one in which terrestrial subscribers cannot access cloud content at low latency. In a terrestrial wireless network, a high latency arises when there is network congestion or network overloading. The occurrence of network congestion results in a low aggregate throughput in the network segment as well as a high latency. Existing research has considered the use of unmanned aerial vehicles to enhance the capacity of existing terrestrial wireless networks in several contexts [40, 41, 44]. Hence, unmanned aerial vehicles are suitable for addressing the challenge by providing an alternative path for accessing cloud content. Hence, unmanned aerial vehicles provide a cyber-physical extension (window) into the cloud platform. The proposed cyber-physical cloud comprises a central cloud platform or data center with several cloud extensions (windows). The use of the cyberphysical cloud also enhances the ability of space tourists to access cloud content. In this case, the space tourist is in the terrestrial plane when the condition E1ð Þ *sz* ≤ *lth* is observed to hold true. Hence, the proposed cyber-physical cloud access system also enhances the provision of cloud based content to the internet.

In the cyber-physical cloud, the central cloud platform connects to the terrestrial wireless network and the cyber-physical windows as shown in **Figure 4**. In **Figure 4**, the cloud connects to either the aerial vehicle or the terrestrial wireless network. The subscribers desiring access to cloud based content are connected to the base station or the aerial vehicle. In the event that E1ð Þ *sz* ≫ *lth*, the notification is sent to the cloud and aerial vehicles are deployed.

The condition E1ð Þ *sz* ≫ *lth* is verified at the cloud platform using information on the latency associated with data reception by each individual desiring access to cloud content. Each subscriber receiving content from the cloud via own terminals send information on the latency associated with content reception to the cloud platform. The usage of the term aerial vehicle implies both manned aerial vehicles (MAVs) and unmanned aerial vehicles (UAVs). The joint usage differs from the approach where only UAVs are used in the system [54].

**Figure 3.** Functional flowchart showing the execution of the proposed handover for the space vehicle i.e. MAV.

The sole use of UAVs in the absence of aerial diversity does not consider regional aviation safety concerns. The incorporation of MAVs with UAVs enables the use of aerial vehicles in a manner that meets aviation safety concerns. For example MAVs are human driven and can be used in areas with constraints on aviation safety. The MAV is an aerial vehicle with smaller dimensions than the conventional manned aircraft; it is equipped with a communication payload that enables data communication with the cloud platform.

In the cyber–physical cloud, the central cloud platform connects to the terrestrial wireless network and the cyber–physical windows as shown in **Figure 4**. In **Figure 4**, the cloud can connect to either the aerial vehicle or the terrestrial wireless network. The subscribers desiring access to cloud-based content are connected to the base station or the aerial vehicle. In the event that E1ð Þ sz *>* lth, the notification is sent to the cloud and aerial vehicles are deployed.

The condition E1ð Þ sz *>* lth is verified at the cloud platform using the information on the latency associated with data reception by each individual desiring access to cloud content. Each subscriber receiving content from the cloud via own terminals sends information on the latency associated with content reception to the cloud platform. The usage of the term aerial vehicle implies both MAVs and UAVs. The joint usage differs from the approach where only UAVs are used in the system [54]. The sole use of UAVs in the absence of aerial diversity does not consider stringent regional aviation safety concerns. The incorporation of MAVs with UAVs enables the use of aerial vehicles in a manner that meets stringent aviation safety concerns. For example, MAVs are human driven and can be used in areas with stringent constraints on aviation safety. The MAV is an aerial vehicle with smaller dimensions than conventional manned aircraft. It is equipped with a communication payload that enables data communication with the cloud platform.

**Figure 4.** Incorporation of MAV and UAV into enabling cloud access.
