# Low Power FPGA Implementation of a Smart Building Free Space Optical Communication System  
[PERSON]  
1 Electronics and Communication Engineering Department, Arab Academy for Science, Technology and Maritime Transport, Giza P.O. Box 2033, Egypt; [EMAIL_ADDRESS] (R.A.); [EMAIL_ADDRESS]t.edu (H.H.A. ); [EMAIL_ADDRESS] (S.M.E.) [PERSON]  
2 Electronics and Communication Engineering Department, Arab Academy for Science, Technology, and Maritime Transport, Cairo P.O. Box 2033, Egypt; [EMAIL_ADDRESS] (R.A.); [EMAIL_ADDRESS].edu (H.H.A. ); [EMAIL_ADDRESS] (S.M.E.) [PERSON]  
1 Electronics and Communication Engineering Department, Arab Academy for Science, Technology and Maritime Transport, Giza P.O. Box 2033, Egypt; [EMAIL_ADDRESS] (R.A.); [EMAIL_ADDRESS]t.edu (H.H.A. ); [EMAIL_ADDRESS] (S.M.E.) [PERSON]  
1 Electronics and Communication Engineering Department, Arab Academy for Science, Technology and Maritime Transport, Giza P.O. Box 2033, Egypt; [EMAIL_ADDRESS] (R.A.); [EMAIL_ADDRESS].edu (H.H.A. ); [EMAIL_ADDRESS] (S.M.E.) [PERSON]  
1 Electronics and Communication Engineering Department, Arab Academy for Science, Technology and Maritime Transport, Cairo P.O. Box 2033, Egypt; [PERSON]DRESS] (H.H.A. ); [EMAIL_ADDRESS] (S.M.E.) Footnote 1: email: {de,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,  
Successful low-cost and versatile wireless communication between neighboring buildings can be developed for sharing each building's security recognition and zone conditions on a frequent monitoring basis. To begin with, optical wireless communications have set up different platforms and territories for placing successful communication spots. Data from Ref. [5] emboldens the classifications of optical wireless technologies, as shown in Figure 1.  
For outdoor FSO links applications, there are two types of networks: space links and terrestrial links. The primary motivation for establishing such a network is to provide global internet coverage, i.e., the ability to communicate between any two points on Earth, particularly in areas where terrestrial internet is scarce or nonexistent. One of the pioneering technologies in satellite communications is StarLink which is described as a huge low earth orbit (LEO) constellation created by SpaceX for providing global coverage, high bandwidth, and low latency satellites [6; 7]. For smart building communications, a line of sight (LOS) FSO link between buildings is the item of recognition and the main focus of this research. In recent years, there has been an extremely competitive aspect between conventional wireless communication such as radio frequency (RF) and the newly intriguing alternative technologies involving utilizing signals in an optical form [8]. Among the candidate innovations these technologies offer is the FSO communication system, where a signal is transferred from an electrical to an optical one and carried through a free space medium in the form of a visible light (VL) beam or an infrared (IR) beam. The fact that FSO eliminates most of the cons of RF communication makes it a strong opponent technique nowadays [4; 5]. The presence of linked sensors or devices in the city is required for these applications, giving the green light for new alternative linkages to step in. Mobile and network operators must adjust their strategies in this scenario to keep up with the city's technological advancements and the conquering of other strategies and infrastructures [9]. FSO technology displays various advantages such as non-necessity of a licensed bandwidth, high security of data and negligibility of interference and jamming occurrence, higher data rates, and cheaper rollout cost. With these advantages come some challenging situations an FSO network can encounter, including weather turnovers such as rain and foggy space, atmospheric turbulence, scintillation, scattering, etc. [10]. Table 1 shows a detailed comparison between RF conventional wireless technology and optical wireless communications with a distinction of the bandwidth variety between RF bands and OWC bands.