Free Space Optics Backhaul Link For Small Cells Of 5g Cellular Networks

One of the technologies that use modulated optical beams to transmit information through the atmosphere is Free Space Optics (FSO). In cellular networks, most of the users at the cell edge boundaries suffer frequent interruption of wireless services due to the long distance between them and the donor station. Small cells are introduced as Relay station (RS) by LTE-A cellular networks to help solve this problem and guarantee appropriate cellular link. This work proposed a new approach to increase the number of users and throughput and enhance the capacity of the user by using two links; the first is FSO links between distributed RSs while the second is radio link (RL) between donor eNB and RS. Based on SNR and outage probability, RS placements are mathematically derived to alleviate the interferences with increasing the coverage in 5G cellular networks. The experiments showed enhancements in the received signals from -84.2 dBm to 67.7 dBm by deploying the RSs at selected placements; moreover, there was an increase in the received power from -30 dBm to 0 dBm by using FSO link in compassion with RL.