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Performance Evaluation of Hybrid FSO-SACOCDMA System under Different Weather Conditions
摘要： Spectral amplitude coding optical code division multiple access (SACOCDMA) is a multiplexing technique, which provides faster speed, efficiency, security and unlimited bandwidth. It is widely preferred because of its ability to eliminate multiple access interference (MAI). Free space optics (FSO) provides a wireless link to transmit data securely at higher rates for last mile access. In this work, a 100 Gb/s hybrid FSO-SACOCDMA is designed using direct detection. The performance of FSO using SACOCDMA utilizing NZCC (New Zero Cross Correlation) code is evaluated under different weather conditions (clear weather, haze and fog) for ten users where each user carries 10 Gb/s. The results indicate that in clear weather FSO distance can be extended up to 13 km. Moreover, after using pre-amplifier in clear weather, FSO enhances the maximum distance to 35 km with acceptable signal to noise ratio and bit error rate. Using an amplifier in the link not only makes the quality of the signal better but it also increases the communication range.
关键词： spectral amplitude coding optical code division multiple access (SACOCDMA),free space optics (FSO),direct detection (DD),new zero cross correlation (NZCC)
更新于2025-09-23 15:23:52
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[IEEE 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Jeju (2018.10.17-2018.10.19)] 2018 International Conference on Information and Communication Technology Convergence (ICTC) - Performance of SIM/S-QAM FSO Systems with Phase Errors in Gamma-Gamma Turbulence Channels
摘要： In this paper, we study the performance of subcarrier intensity modulation (SIM) squared quadrature-amplitude modulation (S-QAM) free-space optical (FSO) communication systems considering the atmospheric turbulence-induced phase error in fading channel. The atmospheric fading channel is modeled by Gamma-Gamma distribution while the Tikhonov model is used for the turbulence-induced phase error. The numerical results quantitatively show the impact of atmospheric turbulence parameters to the performance of FSO systems in terms of average symbol-error probability (ASEP) and the power penalty. Besides, the theoretical results are validated through Monte Carlo simulation to confirm our analysis.
关键词： Free-space optics (FSO),Phase error.,Atmospheric Turbulence,Fading Channel,Squared quadrature-amplitude modulation (QAM)
更新于2025-09-23 15:22:29
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[IEEE 2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA) - Coimbatore (2018.3.29-2018.3.31)] 2018 Second International Conference on Electronics, Communication and Aerospace Technology (ICECA) - FSO Link Performance Analysis with Different Modulation Techniques under Atmospheric Turbulence
摘要： Free space optics (FSO) has achieved prominence in extremely large bandwidth, unlicensed spectrum and low power secure transmission in the field of wireless communication. Despite the advantages, it is deeply impacted due to atmospheric turbulence and fog weather conditions. This paper considers different modulation schemes under the presence of atmospheric turbulence and fog conditions. The desired expression of bit error rate (BER) is obtained by modeling the turbulence as gamma-gamma distributed channel and under this channel condition, 16-PPM has provided better performance than other schemes. BER is considered for the channel performance evaluation. This analysis can help to adopt a modulation technique according to the channel condition.
关键词： Bit error rate (BER),gamma-gamma distribution,atmospheric turbulence,Free space optics (FSO),Meijer’s G function
更新于2025-09-23 15:21:21
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - An Optical Communication System Adjusting Method for GEO Satellites
摘要： In this paper, we proposed an optical communication system adjusting method for the geostationary-earth-orbit (GEO) satellites. The proposal is demonstrated and evaluated by theoretical analysis and experiments. It is able to guarantee not only the coherent detection communications among the GEO satellites but also the direct detection communications between the GEO satellite and the low-earth-orbit (LEO) satellite.
关键词： System Adjusting Method,LEO Satellites,Free Space Optics (FSO),GEO Satellites
更新于2025-09-16 10:30:52
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Efficient Optical Alignment Technique for Compact 100 and 400 GbE TOSAs with Integrated Multiplexing with Free Space Optics
摘要： An efficient and low-cost optical alignment technique is for the first time established for compact transmitter optical sub-assemblies (TOSAs) with an integrated multiplexer based on free space optics (FSO) for 100 and 400 Gbps Ethernet (GbE) applications. A compact FSO system for the 100 GbE TOSA is fabricated in a compact package 6.5 mm × 15.1 mm × 5.6 mm in size to confirm the validity of the technique. It is demonstrated by experiment that the optimum optical alignment condition can successfully be figured out by this technique without any expensive equipment, which has been a significant issue for TOSAs with integrated FSO systems, confirming the validity of the technique. Further, Monte Carlo simulations show that the optical output power distribution across the lanes is compatible with the 100 GbE LR4 specification, indicating the suitability of the proposed low-cost alignment technique. It is also shown that the acceptable long-term power variation required for reliability is predicted owing to the relaxation of the positional tolerance of the collimator lenses, which is obtained by the proposed technique. Finally the feasibility of the technique is discussed for 400 GbE TOSAs with eight-lane optical systems.
关键词： transmitter optical sub-assembly (TOSA),laser diode (LD),100 and 400 Gbps Ethernet (GbE),Free space optics (FSO),hybrid integration
更新于2025-09-10 09:29:36
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Network Topology Reconfiguration for FSO-based Fronthaul/Backhaul in 5G+ Wireless Networks
摘要： Using free space optics (FSO) in the mobile fronthaul/backhaul networks is a promising solution that can potentially enhance the capacity of mobile networks. The main challenge of establishing FSO-based fronthaul/backhaul networks is the dynamic feature of the networks, i.e., the fragile links under adverse weather conditions and the dynamic traf?c demands among small cells. Topology recon?guration is proposed to dynamically rearrange the FSO links. In this paper, two types of network recon?gurations are investigated, in which the proactive network recon?guration is to proactively optimize the topology of the FSO-based fronthaul/ backhaul networks for each speci?c time period based on the statistics of the network, and the reactive recon?guration is to actively adjust the topology when traf?c demands and link states are changed. The proactive network recon?guration is formulated as a mixed integer nonlinear programming (MINLP) problem, which jointly optimizes the network throughput and power consumption of FSO-based fronthaul/backhaul networks. A greedy algorithm is proposed to derive the solution of the proposed problem. After the network topology having been recon?gured by solving the MINLP problem, two reactive recon?guration algorithms are designed to optimally adjust the network topology once a link failure and demand explosion occur, respectively, to further enhance the network throughput and reduce the power consumption. The performance of the algorithms is demonstrated via extensive simulations.
关键词： FSO-based fronthaul/backhaul,multi-criteria optimization,topology recon?guration,free space optics (FSO)
更新于2025-09-09 09:28:46