On the performance of a mixed RF/MIMO FSO variable gain dual-hop transmission system

Abstract

In this work, we propose a mixed radio frequency (RF) and multiple-input-multiple-output (MIMO) free-space optical (FSO) system based on a variable-gain dual-hop relay transmission scheme. The RF channel is modeled by Rayleigh distribution and Gamma-Gamma turbulence distribution is adopted for the MIMO FSO link, which accounts for the equal gain combining diversity technique. Moreover, new closed-form mathematical formulas are obtained including the cumulative distribution function, probability density function, moment generating function, and moments of equivalent signal-to-noise ratio of the dual-hop relay system based on Meijer's G function. As such, we derive the novel analytical expressions of the outage probability, the higher-order fading, and the average bit error rate for a range of modulations in terms of Meijer's G function. Furthermore, the exact closed-form formula of the ergodic capacity is derived based on the bivariate Meijer's G function. The evaluation and simulation are provided for system performance, and the effect of spatial diversity technique is discussed as well.

Exact Outage Probability Analysis of the Mixed RF/FSO System With Variable-Gain Relays

“…When system consists of only one relay and the second FSO hop is affected by the GG atmospheric turbulence with the pointing errors, the outage probability is derived by substituting M = l = 1 into (16), which represents the result already reported in [15, eq. (23)].…”

“…When the pointing errors are neglected, i.e., ξ → ∞, the FSO hop is only affected by GG atmospheric turbulence. After using [34, 16.0002.01)] to find the limit of (16) for ξ → ∞, and assuming that the relay with the best estimated CSI is always available (M = l), the result in (16) is simplified to the corresponding one in [35, (15)].…”

Performance analysis of mixed RF/FSO system with CCI

“…Since h SR is subjected to Rayleigh fading, follows exponential distribution as [18]: As , is the sum of N independent random variables which are subjected to the exponential distribution. The Laplace transform method is adopted to derive the moment generating function (MGF) of as .…”

“…Moreover, novel closed‐form expressions for outage probability (OP), symbol error rate (SER) and ergodic capacity [14–16] were further presented based on mixed RF/FSO system. On the basis of this the performances of different relay strategies were evaluated including decode‐and‐forward (DF) relay and amplify‐and‐forward (AF) relay [17, 18]. More specifically, AF relay can be divided into fixed gain and variable gain relay schemes.…”

On performance analysis of hybrid FSO/RF systems

“…The mixed FSO/RF system provides good performance advantages when operated at high signal‐to‐noise ratio (SNR). Otherwise, the system's performance is severely degraded in case of low SNR [20–34].…”