Reflecting-Intelligent-Surfaces (IRS)-Assisted Free Space Optical (FSO) Link Performance

Free space optics (FSO) plays a crucial role in establishing connections within remote locations, particularly in challenging areas where optical fiber deployment is impractical. The foremost limitations of FSO transmission lie in its line-of-sight (LoS) requirements and susceptibility to atmospheric turbulence (AT). To overcome these challenges, an innovative approach is employed: optical intelligent reflecting surface (IRS)—enhanced FSO link coverage. This approach effectively relaxes the stringent LoS requirements, making IRS-blended FSO systems a dependable and efficient alternative, particularly for last-mile access connectivity. In the study, the composite impact of atmospheric turbulence, path loss and pointing error issues are modeled for both optical IRS-based FSO link and multiple optical IRS-based FSO links. The IRS-FSO link achieves an average symbol error rate (ASER) of 10–7 while without IRS, FSO link gives 10–4 with Gamma-Gamma and 10–2 with generalized Málaga distribution models at the SNR of 30 dB. Furthermore, as the number of IRS modules increased up to 128, IRS-FSO link performance is drastically enhanced and achieves ASER of 10–12 at the lower SNR value of 20 dB.