Misalignment fading effects on the ACC performance of relay-assisted MIMO/FSO systems over atmospheric turbulence channels

Abstract

<span>The continuous development of internet of things (IoT) technology enables many devices to be interconnected through the external environment. Meanwhile, 5G technology provides an enhanced quality of services with high data transmission rates, requiring IoT implementation in the 5G architecture. Free-space optical communication (FSO) is considered a promising technique that can provide high-speed communication links, so FSO is an optimal choice for wireless networks to fulfill the full potential of 5G technology, providing speeds of 100 Gb/s or more. By implementing 5G features in IoT, IoT coverage and performance will be enhanced by using FSO models. Therefore, the paper proposed and investigated the multiple-input and multiple-output/free-space optical communication (MIMO/FSO) model using subcarrier quadrature amplitude modulation (SC-QAM) and relay stations over atmospheric turbulence channels by log-normal and gamma-gamma distribution under different turbulence conditions. The performance is examined based on the average channel capacity (ACC), which is expressed in terms of average spectral efficiency (ASE) parameters while changing the different parameters of the model. The mathematical formulas of ACC for atmospheric turbulence cases are calculated and discussed the influence of turbulence strength, the different number of relay stations, misalignment effects, and different MIMO configurations.</span>

Average symbol error rate analysis of reconfigurable intelligent surfaces based free-space optical link over Weibull distribution channels

“…We substitute ( 9) and ( 10) into (7), and the probability density function of end-to-end SNR 𝑓 𝛾 (𝛾) can be evaluated as (11). With the help of ( 13) and get the exact PDF of SNR.…”

“…In recent years, there have been studies that have used the RIS technique, the results show the superiority of this technique. However, the transmission parameters have not been fully evaluated (atmospheric attenuation, atmospheric turbulence, and pointing errors); quadrature amplitude modulation (QAM) technique and average symbol error rate (ASER) have not been used yet [6]- [16]. RISs offer wireless communication link advantages and features over technologies such as optical relays of FSO systems [17]- [26].…”

Performance enhancement of FSO link with RIS-aided over Weibull distribution for 5G/6G and IoT applications

“…The parameter used to evaluate performance of system is average channel capacity, is a random variable, ⟨𝐶⟩. As mentioned in the abstract, the average spectral efficiency (ASE) can also be represented by ACC, the ASE of systems can be given by [6].…”

Average symbol error rate analysis of reconfigurable intelligent surfaces-assisted free-space optical link over log-normal turbulence channels

“…quadrature to in-phase decision distance ratio, 𝑀 𝐼 is in-phase and quadrature signal amplitudes, respectively, 𝑀 𝑄 is quadrature signal amplitudes. The (13) can be represented as(15):…”