Diversity aided millimeter‐wave/free space optical cooperative relaying systems

Abstract

In this paper, we investigate the performance of mixed millimeter-wave (mmWave)/multiple input multiple output (MIMO)-free space optics (FSO) cooperative relaying system. The mmWave link is assumed to undergo multipath fading and shadowing which has been modeled as generalized-K distributed fading, whereas the diversity aided FSO link is considered to experience Gamma-Gamma turbulence. We consider amplify-and-forward (AF) relaying strategy and multiple signals arriving at the receiver are combined using equal gain combining (EGC) scheme. Analytical closed form expressions for performance metrics such as outage probability, bit error rate (BER), and the ergodic channel capacity are derived in terms of bivariate Fox's H-function for the considered mixed mmWave/MIMO-FSO relaying system. In order to further simplify the obtained results, we analyze the system performance for the case of high signal-to-noise ratio (SNR) to present the asymptotic expressions for the outage probability and BER in terms of elementary functions. To this end, we have formulated an optimum power allocation scheme which minimizes the probability of outage experienced by the end user by allocating the optimum power on the FSO link. We also analyze the proposed system for the impact of pointing errors in a separate section by deriving closed-form expressions for the outage probability and BER. Finally, numerical results have been demonstrated the findings of the research work which have supplemented by Monte Carlo simulations.

Wheel‐based 5G fronthaul/backhaul hybrid MDM‐NGPON/FSO system under Gamma‐Gamma turbulence and weather effects

“…FSO channel is incorporated as a backup protection link in wheel architecture when the geographic locations are too complicated or unstable to install optical fiber links owing to the huge mountain, rocky terrain, wider river, and other badsurrounding environment. 23,24 As depicted in Figure 2A, eight DS and eight US transceivers are employed at two distinct donut modes in the proposed architecture. At OLT, the modulated DS incoming signals obtained at 8:1 array waveguide grading (AWG) multiplexer (MUX) operating at both modes 0 and 1 are multiplexed at 2:1 AWG MUX and then forwarded to optical distribution network (ODN).…”

“…A four‐level quadrature amplitude modulation (4‐QAM) modulation format is employed in the proposed system as it can transmit high speed (>100 Gbps) information over transmission link and offers optimum performance in terms of receiver sensitivity. FSO channel is incorporated as a backup protection link in wheel architecture when the geographic locations are too complicated or unstable to install optical fiber links owing to the huge mountain, rocky terrain, wider river, and other bad‐surrounding environment 23,24 …”

Unified Performance Analysis of Dual-Hop Radio Frequency/Free Space Optical System

“…In this, communication takes place over two steps where the source and relay are connected via the RF channel in the first step, while the relay and destination are connected via the FSO channel in the second step. Several relaying protocols such as decode-and-forward (DF) [7] [8] and amplify-and-forward (AF) [9][10] [11] have been employed and out of them, AF is more widely used because of their simplicity [11].…”