5G-28 GHz Signal Transmission Over Hybrid All-Optical FSO/RF Link in Dusty Weather Conditions

Abstract

5G wireless networks promise to provide massive bandwidth for various types of connections. In such networks, the backhaul/fronthaul sections should be easy to deploy and support the required high bandwidth. To improve the free space optic (FSO) link bandwidth so that it can replace fiber cables and support 5G networks, all-optical FSO systems were proposed which exploit advanced modulation formats in the transmitter side and coherent detection in the receiver side. However, such links will suffer much under harsh outdoor environment, especially under fog and dust conditions than traditional FSO links that have limited bandwidth. Effect of fog on such links has been investigated in the literature. However, the dust effect is not covered. In this paper, we first experimentally analyzed the effects of dust storms on the performance of an all-optical FSO link carrying a 1-Gbaud/16-quadrature amplitude modulation 5G signal. The results demonstrate that the all-optical FSO link is significantly affected by low visibility range, with severe bit-error-rate (BER), and error vector magnitude (EVM) limits appearing at a 50-m visibility range for a 2.7-m channel length. For a visibility range greater than 200-m, the BER and EVM were improved to 10 −9 and 5.5% of the root mean square, respectively. Furthermore, the analysis showed that the dust storm condition introduces flat fading over the frequency range under study, i.e., 21-29 GHz. Second, a comparison between FSO and radio frequency (RF) channels under the same dusty conditions were performed. The results showed that the effects of the dust storm are negligible for the RF link which makes it suitable as a backup for FSO link under severe dust conditions. Finally, a hybrid cascaded FSO/RF link was installed and analyzed in terms of visibility range, BER, and EVM.

M-QAM transmission over hybrid microwave photonic links at the K-band

“…In 2018, we demonstrated 100 MHz 64-QAM transmission at different carrier frequencies of 24-26 GHz using a low-cost directly modulated laser over 2 m turbulent FSO and 3.6 m RF wireless links with the lowest measured EVM of 4.7% [13]. Very recently, the transmission of 1 Gbaud 16-QAM at 28 GHz over a 0.9 m FSO channel with dust and a 1 m RF wireless link was demonstrated with a bit error rate (BER) well below the hard-decision forward-error-correction (HD-FEC) limit of 3.8×10 −3 [14].…”

Transmitters for Combined Radio Over a Fiber and Outdoor Millimeter-Wave System at 25 GHz

“…The average S 21 magnitude difference between Transmitters B and C was 7 dB, mainly caused by the modulation depth. The DML in Transmitter A was designed to operate over a wider frequency range of up to 40 GHz [26], however, its S 21 performance was highly influenced by the frequency profile of the photodetector used and, in particular, by the bias tee. It resulted in a less flat characteristic compared to Transmitters B and C. The S 21 measured at frequency of 25 GHz were −53.9, −32.3 and −24.2 dB for Transmitters A, B and C, respectively.…”

“…An RoF transmission over 20 km of SSMF and 10 m long RF free space channel including photonic mm-wave generation at 60 GHz for 5G fronthaul using MZM was presented in [24]. A microwave photonic link using the combination of free space optics (FSO) and 1 m long RF wireless channel operating at a frequency of 28 GHz was shown in [25] [26]. In addition, our previously published work [27] showed the most detailed experimental demonstration of RoF using DML that includes radio over free-space optics and a 3.3 m long indoor wireless free-space RF channel in the frequency band of 24-26 GHz.…”

Key Challenges, Drivers and Solutions for Mobility Management in 5G Networks: A Survey

“…This is due to the introduction of the mm-wave bands which provide very short coverage due to their high path loss characterization [21,[66][67][68][69][70]. For example, 28 GHz is one of the best candidate frequency bands that can be implemented in 5G networks, but this frequency band can only support up to 200 meters in Line-Of-Sight (LOS) [71,72]. To cover an area of a few kilometers by the 5G network, a high number of small 5G BSs must be deployed, compared to the previous generations.…”