THz Links Performance Study for Gamma Turbulence Links with Path Loss and Pointing Errors

Energy-Efficient Emerging Optical Wireless Links

“…Consequently, the turbulence effect plays a key role in the energy efficiency and outage performance of typical UV links. More recently, in the penultimate row in Table 2, which refers to [106], the more compact K-distribution model has been introduced in the UV area along with the time diversity technique. The former has been proven to be accurate for strong turbulence conditions, while the latter has been proven to be a useful tool to address these strong turbulence-induced UV irradiance scintillations in an attempt to create more robust and energy-efficient UV systems.…”

“…Bearing in mind that the LN model is one of the most accurate models for weak to moderate turbulence-induced scintillation in the traditional infrared FSO area, the latter findings paved the way to adopt, adjust, and incorporate several well-known FSO distribution turbulence models in the emerging UV-C area. Indeed, the unifying Malaga distribution has been recently introduced in [103] for weak to strong turbulent UV-C links, the generalized Gamma-Gamma distribution has been utilized in [104,105] under the same wide turbulent range and, more recently, the K-distribution has been employed in [106] for strong to very strong turbulent UV-C links.…”

“…It is remarkable that in [104][105][106][107][108][109][110][111][112][113][114][115][116][117][118][119][120], diversity techniques have been investigated and utilized either theoretically or experimentally, in order to enhance the total UV-C system's performance and availability toward an energy-efficient direction. Indeed, these illustrative successful examples are in [112], where for a target BER of 10 −6 over a 1 km UV system operating at 260 nm, a SNR of 36 dB was required for the SISO configuration, while this requirement reduced to 33.5 dB and 32.5 dB, offering performance gains of 2.5 dB and 3.5 dB for MISO link configurations with two and three transmitters, respectively.…”

“…Recently, the authors in [105], through the Gamma-Gamma turbulence model, along with the proposed maximal selective transmit diversity with the transmit power set to 20 dBm, i.e., 100 mW for a 200 m UV link, achieved BER = 3 × 10 −12 and BER = 5 × 10 −11 for weak and strong turbulent channels, respectively. In addition, the authors in [106], through the proposed time diversity technique for NLOS UV links operating at 260 nm, assessed the required power values to transmit at a wide range of average BER targets. Even in very strong turbulence, the SISO link (with no diversity) required 18 dBm, i.e., 63.1 mW for a target average BER = 2 × 10 −10 , while by employing time diversity, the virtual SIMO link transmitted power of 18 dBm, i.e., 63.1 mW could achieve an average BER = 10 −13 , for 200 m propagation distance in all these link configurations.…”

Outage Probability Analysis of HARQ-Aided Terahertz Communications

“…6 that the HARQ-IR aided THz communications achieve a better outage performance than HARQ-IR aided FSO communications. This can be explained by the conclusion drawn in [51] that the FSO system frequently suffers from severe atmospheric turbulence and pointing errors compared to the THz system. Hence, our results coincide with the experimental observations in [51].…”