Fig 2 - uploaded by Jayeshkumar Chelabhai Prajapati
Content may be subject to copyright.
Source publication
Free Space Optics (FSO) has received much attention in recent years as a cost – effective, licence free and wide-bandwidth access technique for high data rates applications. Single beam FSO and multiple beam FSO system is designed and analyzed to produce the best system capable of tackling the effect of atmospheric weather conditions. Hybrid wavele...
Context in source publication
Context 1
... the FSO system is a well-studied topic, the appearance of WDM technique has become a new study in communication area. A WDM system is designed to overcome the challenge of FSO signal degradation due to atmospheric attenuation which is shown in Figure 2. WDM has higher capacity so high data rate with longer link distance is also possible. ...
Citations
... On the signal, the effect of attaining aperture was performed in this work and in the clear weather illustrated more than 180 Km communication link, among the data rate of 2.5 GHz its 54.5 km in haze. Nishu Sahu [28] had projected a hybrid 16 channel 2.5 Gb/s WDM multi-beam FSO communication mechanism which had 16 wavelengths among 100 GHz channel spacing. The presentations of the conventional mechanism and the projected mechanism like the WDM FSO mechanism and WDM multi-beam FSO mechanism was compared. ...
Free space optics (FSO) has transformed the telecom industry due to its beneficial features such as high data transmission capacity and cost-effectiveness. In wireless communication, the utilization of WDM-FSO is performed for modulating the signal carriers. The obtained modulated signals are transmitted by using a laser beam. Basically, WDM is deployed to exploit the available channel capacity in an efficient manner. However, WDM-FSO communication is highly susceptible to the issues associated with the atmosphere or ambient conditions. The FSO link is used as a transmission link that is affected by the attenuation. The attenuation in the carrier signals take place due to various environmental conditions (fog, rain, storm, snowfall, etc). The existence of such foreign elements in the transmission link introduces the noise to the carrier signals and in this manner, the actual information gets affected. This also results in the increment in the BER and decrement in the Quality factor. This study is organized to have a review of the various atmospheric conditions that degrade the quality of the communication. The major focus of the study is to analyze the FSO-WDM system with multiple weather conditions such as heavy rain, haze, etc as such conditions increase the occurrence of attenuation in signal in the WDM system which directly reduces the Q factor of the communication. Along with this, the study also investigates the various implementations that had been done in the past to enhance the efficiency of the FSO-WDM system by utilizing various advanced techniques such as modulations, etc.
... Furthermore, the FSO system was investigated under two different approaches, namely, single wavelength system (Savojbolaghchi et al. 2019) and wavelength division multiplexing (WDM) system (Hsu et al. 2013;Rashidi et al. 2017;Esmail et al. 2017) and most published articles for FSO based WDM system were theoretically works, especially via OptiSystem software (Fadhil 2013;Sahu and Prajapti 2015;Biswas et al. 2017;Singh 2018). This due to, the high cost of the equipment as well as difficulty dealing with WDM problems based wireless system in terms of; transmitting amplification and receiving. ...
In this paper, the performance of multiwavelength free space optical (MFSO) communication system is enhanced via optimization of the transceiver design parameters. The performance of the proposed system is investigated and compared with the previous work under the same weather condition, as well as with and without misalignment losses (ML). The optimum transceiver design parameters of the proposed system are 15 cm, 20 cm and 1 mrad for transmitter, receiver diameter and beam divergence, respectively. According to the results, the maximum achievable distance at the communication conditions (6 for Q-factor and 1e−9 for BER) is about 5.1 km and 22 km for the system with and without ML, respectively within very clear weather condition. While, for hazy weather, these distances are reduced to 4.1 km for the system with ML and 8 km without ML. Furthermore, it’s represents an enhancement about 7.3% for the system with ML and 363.15% for the system without ML as compared with previous work.
In the current networked world, technical advancements in Internet of Things (IoT) along with 5G communication technology have made free space optical communication (FSO) quite popular as it enhances bit rate in 5G communication and strongly supports large scale connecting links in IoT networks. Specific to real-life implementation schemes, it can be observed that an optical fiber cable link towards receiver end is a mandatory requirement in realization of FSO scheme. This results in a combined network architecture known as a hybrid free space optic/fibre optic (FSO/FO) communication network. The possible network scenarios as well as advantages of cascading dispersion compensating fiber (DCF) and chirped fiber bragg grating (CFBG) in the fiber link related to receiver end in dense wavelength division multiplexing (DWDM) hybrid FSO/FO networks has been investigated in this work. By optimizing parameter values of double FSO channels and CFBG in our hybrid FSO/FO system used in Optisystem software, for clear weather, the maximum link ranges have been recorded as 54 Km and 14 Km excluding and considering Misalignment Losses (ML) respectively. For Hazy weather, the corresponding values were recorded as 9.6 Km without ML and 6.7 Km considering ML attenuation. Highest Quality factors (Q factor) for the first channel, inclusive of ML attenuation, were found to be 6.42 and 6.9 for clear and hazy atmospheric conditions, respectively. The designed hybrid FSO/FO network proved to perform better compared to existing architectures, specifically with respect to link range.
In this work, the integration of free-space optics (FSO) technology for implementing long-haul high-altitude platform (HAP)-to-ground transmission system is proposed. Mode division multiplexing (MDM) and orthogonal frequency division multiplexing (OFDM) are incorporated for carrying high-speed signals without interference. The impact of increasing input power, divergence angle, antenna diameter, and attenuation on the system performance is further investigated. In addition, the performance of the MDM-OFDM-HAP-to-ground FSO transmission system is improved by using a square root module at the receiver for link reach enhancement. The results exhibit a reliable transportation of 40 Gbps information over 20 km FSO distance with good quality of the received signal.
This work is focused on transmission of duobinary and alternate mark inversion (AMI) modulation, adopting mode division multiplexing (MDM) of Laguerre Gaussian (LG) modes has been capitalized in wavelength division multiplexing (WDM) system, resulting in a 1.6 Gbps eight-channel free space optical communications (FSO) system. The simulation results show that duobinary offers better bit error rate (BER) performance compared to AMI for proposed hybrid MDM-WDM-FSO system.
Free space optics represents a fast and economical method to transmit digital data at the speed of the order of the Gbps at a distance of a few kilometers. The major limitation is the atmospheric attenuation, especially fog, which can affect the quality of transmission, transfer rate and transmission distance. A useful metric to monitorize the processes is the BER factor. This paper proposes a combination of adaptive optics that use multiple heads of transmission which are focused simultaneously on a single photodetector at the receiver end, in order to provide redundancy and to sustain a minimum data-rate transfer and/or assuring a transmission distance at an acceptable BER. It is assessed, through the simulation, the optimal (technically and economically) number of optical transmitters for which we get a real quality improvement of the transmission for a given bitrate-distance factors.
