## 5 Performance when Using CCIS in AAPS Sky Mesh Network Applications  
Recently, FSO systems have played a noteworthy role in rustic and catastrophe-prone circumstances. They provide definitive data to groups of people and organizations in the aftermath of natural or man-made disasters. A disrupted communications foundation necessitates quick arrangement communication systems to carry out critical assistance; however, communication towers are costly for rural, remote, and geographically challenged areas. Additionally, satellite platforms provide high infrastructure, which increases the costs for each subscriber. The need for a foundation in rural zones and high establishment costs compared to urban regions are the two significant obstacles in building a remote area that would cater to the needs of the local community, particularly when other modes of communication are disturbed [26]. Fiber-wireless (FiWi) communication services are usually provided by terrestrial and satellite systems. The demand for large capacity remote administration is growing, particularly for \"last mile\" conveyance [21]. Existing methods of telecommunication using satellites and telecommunication towers have several limitations. In isolated areas, the performance of communication systems can be enhanced by utilizing an aerial altitude platform system (AAPS), due to the fact that conventional approaches fail to support full access to the data link in rural and isolated areas [21]. Therefore, the AAPS communication system in rural and remote areas is suggested. This technique causes an acceleration in the adoption of the internet and telecommunications by rural communities. The achievability of the framework will be set up through tests and a field trial. The large-scale arrangement of the created framework can play a significant role in bridging the gap between distant communities that are beyond the reach of current telecommunication. The system diagram of the AAPS in a sky mesh network is shown in Figure 13. The method used for data transmission between the primary part, sky station 1 (SS1), and the base, which, in turn, transmits signals to the second node, sky station 2 (SS2), depends on radio frequency (RF) cycles. In the RF cycle, SS1 is connected to the ground station (GS) via IEEE 802.11a, while in the second phase, SS1 is linked to SS2 through RF, and all nodes provide coverage to the ground by utilizing the IEEE 802.11 b/g standard. In this work, we suggest a new method for signal transmission between the sky stations depending on the optical cycle. This method connects the GS to SS1 through a fiber optic cable while SS1 is connected to SS2 via the FSO channel. To be able to examine the performance of FSO, some parameters must be taken into consideration. These parameters can be classified into two categories. The first category considers the internal parameter related to the design of the FSO communication system as transmitted power, as well as bandwidth, beam divergence angle, and BER on the receiver side. However, the second category depends on an external limitation, such as weather conditions, which causes attenuation and may lead to link failure. The relation between the received and transmitted power can be expressed as [26]  
\[P_{R\mathbf{x}}=P_{T\mathbf{x}}\bigg{(}\frac{d_{R\mathbf{x}}}{d_{T\mathbf{x}}+ \theta R}\bigg{)}^{2}\mathbf{10}^{-\frac{\beta R}{10}} \tag{1}\]  
where \(P_{Rx}\), \(P_{T\mathbf{x}}\), \(a_{Rx}\), \(d_{T\mathbf{x}}\), \(\theta\), and \(R\) indicates received power, transmitted power, received aperture diameter, transmitted aperture diameter, beam divergence, and link range, respectively, while \(\beta\) refers to the atmospheric attenuation. The bidirectional FSO transmission and receiving communication system needs a line of sight for both the transmitter and receiver sides. Therefore, a wireless optical beam is used to establish a data bridge between the two nodes (SS1 and SS2).