RELAY SELECTION IN ENERGY HARVESTING AIDED MIXED RF/FSO SYSTEM WITH TRANSMIT ANTENNA SELECTION OVER ATMOSPHERIC TURBULENCE AND POINTING ERROR

In this paper, the performance of relay selection in an energy harvesting aided mixed radio frequency (RF)/free space optical (FSO) system with transmit antenna selection (TAS) over atmospheric turbulence and pointing error is presented. The source of multiple antennas employs TAS to send information to the destination via multiple relay nodes. Also, the energy-limited source uses selection combining technique to harvest energy from multiple relay nodes. As a result, all the relay nodes act as a wireless power transmitting node as well as data receiving node. Moreover, it assumes that the RF/FSO links follow Rayleigh/Malaga (M) distributions with non-zero boresight (NB) pointing error on the FSO link. Therefore, the system outage probability closed-form expression is then derived which is utilized to obtain the system throughput. In addition, the results demonstrate the significant effect of atmospheric turbulence and NB pointing error on the system performance with multiple relays, and source transmit antenna offers the system better performance. The accuracy of the derived expressions is thus validated through Monte Carlo simulations.