###### Abstract
This combined technology can significantly improve the performance of wireless communication networks by taking advantage of the complementary benefits of both connections [14] In this concept, therefore, HAPs can, thus, serve as intermediate relay node to enhance the transmission between the satellite and the ground users by using decode-and-forward (DF) and amplify-and-forward (AF) relaying protocols [13]. Today, security is the most critical challenge in wireless communication system due to the broadcasting nature of RF medium [15]. As a result of this, the ISHAP system is highly susceptible to any external eavesdroppers which have the capacity to intercept the confidential information of the legitimate users via the system RF link. In this view, physical layer security has been suggested to offer better security performance by exploiting the channel characteristics and imperfections without data encryption [16]. Scanning through the open literature, it was found that there have been intense studies on the performance of cooperative satellite-terrestrial relaying networks. A dual-hop satellite communication system with AF relay was presented in Reference [17], where maximum ratio transmission and maximum ratio combiner scheme were adopted at the system source and destination, respectively. In Reference [18], the performance of a hybrid satellite-terrestrial free space optical cooperative network was evaluated, where the system error rate was obtained. In addition, the performance of an AF hybrid satellite terrestrial system over generalized fading channels was investigated in Reference [19], and the authors obtained the analytical expression for the average symbol error rate of the network. In Reference [20], the impact of hardware impairment on the reliability performance of hybrid satellite-terrestrial system was evaluated, where the geosynchronous orbit satellite sends its information to the multiple terrestrial relay nodes. Furthermore, the performance of hybrid satellite-terrestrial network having multi-antennas terrestrial relays was investigated in Reference [21]. It was assumed that there was direct link between the satellite and the destination, and the effect of hardware impairments with the interference on both relay and destination were investigated. The outage performance of a partial relay selection-based hybrid satellite-terrestrial network was analyzed in Reference [22]. In Reference [23], the performance of an underlay hybrid cognitive satellite terrestrial network was evaluated, where the primary satellite coexists with the second terrestrial relay system. The performance of joint impact of CSI and hardware impairments on a cognitive satellite terrestrial relay network was presented in Reference [24]. However, all these aforementioned works only focused on the scenario of single terrestrial user. In this view, future satellite communication network is required to provide reliable and efficient services for a large number of users. As a result of this, many research studies are focusing on evaluating the performance of hybrid satellite-terrestrial multiuser networks. Thus, the performance of a multi-antenna multiusers hybrid satellite terrestrial relay network was studied in Reference [25]. The authors employed opportunistic user scheduling with outdated channel state information (CSI) and AF relaying with co-channel interference. The outage performance of a multi-antenna multiple users integrated in a satellite-unmanned aerial vehicle (UAV) cooperative network was presented in Reference [13]. However, all these works were RF-based multiusers hybrid satellite-terrestrial systems. In addition, the outage performance of a mixed FSO/RF satellite-aerial terrestrial network was evaluated in Reference [26], where the satellite sent messages to multiple users with the help of a multi-antenna aerial platform as a relay. In Reference [27], the performance analysis of a mixed FSO/RF satellite-UAV multiuser network was studied, where the UAV relay node adopts DF relaying protocol. [PERSON] et al.