Statistical Analysis of Noise Propagation Effect for Mixed RF/FSO AF Relaying Application in Wireless Sensor Networks

Abstract

In this paper, we investigate the so-called noise propagation effect in a mixed radio-frequency/ free-space optical (RF/FSO) amplifying-and-forwarding (AF) relaying system that is applied for data transmission in wireless sensor networks. The noise propagation could be essentially severe when battery-charged sensor nodes have very limited transmit power. We provide an exact expression on the cumulative distribution function (CDF) of end-to-end signal-to-noise power ratio (SNR) for a dual-hop mixed RF/FSO AF relaying system. We assume a tightly power-constrained amplifying gain at the relay, which has been usually ignored in existing performance studies for the mixed RF/FSO AF system. It however should be considered to properly evaluate the noise propagation effect especially if the relaying power is not infinite or the sensor has a poor budget in transmit power. We apply the derived exact CDF to evaluate the system performances such as outage probability, average bit-error rate, and ergodic capacity. Numerical investigation is used to justify that the proposed analysis is exactly matched with the simulation and shows that the performance gap caused by the inclusion of the noise propagation effect is significant (about 2–12%) especially when the SNR per hop is in the medium- or the low-SNR ranges (i.e., at 10–20 dB).

Cooperative Terrestrial-Underwater Wireless Optical Links by Using an Amplify-and-Forward Strategy

“…Optical communication systems are currently presented as a very competitive solution for the establishment of high capacity point-to-point wireless links, becoming an alternative [ 1 , 2 , 3 ] or, in the case of new generation networks [ 4 , 5 , 6 , 7 ], a complementary technology. This is the approach that has been included in the development of the 5G+ backbone systems infrastructure standard, which foresees the coexistence of millimeter radio technologies with terrestrial free-space optical (FSO) communications systems [ 8 , 9 , 10 , 11 , 12 , 13 ].…”