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oe1(光电查) - 科学论文

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出版时间
  • 2019
研究主题
  • FSO Communication System
  • Subcarrier Intensity Modulation
  • Atmospheric Turbulence
  • Bit Error Rate
  • Average Irradiance
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Galgotias College of Engineering and Technology
37 条数据
?? 中文（中国） ▾

  • Performance Limits of FSO Based SAC-OCDMA System Under Weather Conditions

    摘要： In this paper, the Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA) is investigated in Free Space Optics (FSO) using Zero Cross Correlation (ZCC) codes to evaluate its performance limits in terms of link range. The system is analyzed under clear, haze, moderate fog and dense fog weather conditions. This system has been evaluated numerically and by simulation analysis by maintaining the transmitted power at 10 dBm, for safety reason, according to International Telecommunication Union (ITU) and minimum acceptable BER of 10–9. The simulation results shown that the present system can transmit 622 Mbps/1 Gbps up to maximum link range of 1450 m/1100 m and 61 m/54 m under clear and dense fog conditions, respectively.

    关键词： fog,haze,free space optic (FSO),spectral amplitude coding optical code division multiple access (SAC-OCDMA),zero cross-correlation (ZCC)

    更新于2025-09-23 15:23:52

  • Adaptive resource allocation in FSO/RF multiuser system with proportional fairness for UAV application

    摘要： The combination of free space optic(FSO) and unmanned aerial vehicle (UAV) can be a promising solution to last-mile problem because of FSO high bandwidth and flexibility of UAV. However, FSO is vulnerable to the atmospheric turbulence and transmitter configuration is limited on UAV. Therefore, in this paper, we investigate an adaptive resource allocation strategy to provide relative fair and high transmission capacity for users. In the proposed network model, the downlink scenario is considered and ground station communicates with UAV and its local users by FSO and RF links, respectively. According to the channel conditions and rate requirements from users, channel and power assignments should satisfy the capacity demand in reasonable. To this end, we decompose the original channel and power allocation problem with high computational complexity into low-complexity subproblems, corresponding to channel allocation in RF transmission phase and channel matching and power allocation in FSO transmission phase. Then, a heuristic efficient resource assignment algorithm is proposed to achieve the optimal capacity distribution for users. Numerical results show that the proposed method can asymptotically achieve optimal throughput. Furthermore, system throughput is higher at low transmitting power requirement than those of other existing methods.

    关键词： UAV,proportional fairness,mixed FSO/RF,efficient resource allocation,channel capacity

    更新于2025-09-23 15:23:52

  • 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

  • Physical Layer Security of Hybrid Satellite-FSO Cooperative Systems

    摘要： In this paper, we study the physical layer secrecy performance of a hybrid satellite and free-space optical (FSO) cooperative system. The satellite links are assumed to follow the Shadowed-Rician fading distribution; and the channel of the terrestrial link between the relay and destination is assumed to experience the Gamma-Gamma fading. For the FSO communications, the effects of different types of detection techniques (i.e., heterodyne detection and intensity modulation with direct detection) as well as the pointing error are considered. We derive exact analytical expressions for the average secrecy capacity (ASC) and secrecy outage probability (SOP) for both cases of Amplify-and-Forward (AF) and Decode-and-Forward (DF) relaying. The asymptotic analysis for the SOP is also conducted to provide more insights on the impact of FSO and satellite channels on secrecy performance. It is found that with the AF with fixed gain scheme, the secrecy diversity order of the investigated system is only dependent on the channel characteristics of the FSO link and the FSO detection type, whereas the secrecy diversity is zero when the relay node employs DF or AF with variable-gain schemes.

    关键词： land mobile satellite (LMS) channel,secrecy outage probability,hybrid satellite free-space optical (FSO) cooperative system,Physical layer security,average secrecy capacity

    更新于2025-09-23 15:22:29

  • Joint Optimal Transceiver Placement and Resource Allocation Schemes for Redirected Cooperative Hybrid FSO/mmW 5G Fronthaul Networks

    摘要： To meet the requirements of the 5G mobile network, a new innovative approach called centralized radio access network (C-RAN) architecture is introduced. In C-RAN architecture, the fronthaul network must provide high capacity, high availability, and low latency to be able to transmit massive traffic between remote radio heads (RRHs) and baseband processing units. In this paper, two joint transceiver placement and resource allocation schemes are proposed for redirected cooperative hybrid free-space optics (FSO)/millimeter-wave (mmW) fronthaul networks. The schemes aim to obtain the optimal FSO/mmW transceiver placement that optimizes reliability, average transmitted power, average bit error rate (BER), and number of disrupted links of redirected cooperative hybrid FSO/mmW fronthaul networks in various weather conditions. The schemes are formulated as multiobjective and bilevel integer linear programming problems and solved by using an exhaustive search method to obtain optimal solutions. The numerical results reveal that improvements are obtained in the network reliability, average transmitted power, and average BER by implementing the optimal placement, especially at low visibility and/or high rainfall rate conditions.

    关键词： C-RAN,FSO,5G,mmW,Optimal transceiver placement,RRH,Resource allocation,BBU

    更新于2025-09-23 15:22:29

  • Precise Performance Analysis of Dual-Hop Mixed RF/Unified-FSO DF Relaying with Heterodyne Detection and Two IM-DD Channel Models

    摘要： This paper provides precise performance analysis of the dual-hop mixed radio frequency (RF)/unified free space optical (FSO) decode-and-forward (DF) relaying system, in which the heterodyne detection (HD) and the intensity modulation-direct detection (IM-DD) are taken into account for FSO detection. To this end, we derive closed-form expressions for the outage probability, average bit error rate (BER), and the ergodic channel capacity of this system. In this analysis, we utilize, for the first time as per our knowledge, a precise channel capacity result for the IM-DD channel. Moreover, this is the first time that not only the (IM-DD input-independent) but also the (IM-DD cost-dependent) AWGN channel is considered in such system analyses. Additionally in this study, we assume that the first hop (RF link) follows Nakagami-m fading, and the second hop (FSO link) follows Málaga (M) turbulence with pointing errors. These fading and turbulence models contain other models (such as Rayleigh and Gamma-Gamma) as special cases, thus our analyses can be seen as a generalized one from the RF and FSO fading models point of view. Also, in BER derivation, we assume that the modulation schemes in the two hops can be different, since not all modulation schemes are suitable for IM-DD FSO links. In addition, the system performance is investigated asymptotically at high signal to noise ratios (SNRs). This investigation leads to new non-reported coding gain and diversity order analyses of such system. Interestingly, we find that in the FSO hop, at high transmitted powers, all the considered FSO detectors result in the same diversity order. Furthermore, we provide simulation results that verify the accuracy of the obtained analytical and asymptotic expressions.

    关键词： Nakagami-m fading,Málaga (M) fading,HD,DF,heterodyne detection,Mixed RF/FSO relay network,IM-DD,decode-and-forward,intensity modulation-direct detection

    更新于2025-09-23 15:22:29

  • [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

  • [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

  • IEEE Access Special Section Editorial: Optical Wireless Technologies for 5G Communications and Beyond

    摘要： Wide bandwidth and dense spatial reuse are of extreme importance for future wireless communication networks, including 5G and beyond. In particular, these properties are important to enable future wireless networks to cope with the explosive increase in the demand for high data-rate communications. Optical wireless communications (OWC) is a promising technology for achieving this goal due to the abundant reusable license-free optical spectrum. This potential of OWC attracted significant global attention both from communications and optoelectronics viewpoints, and continues to do so.

    关键词： 5G,beam-steering,mixed FSO/fiber backhauling,OFDM,MIMO,Optical wireless communications,vehicle-to-vehicle communications,free-space optics,vehicle-to-infrastructure communications,network-layer aspects,visible-light communications

    更新于2025-09-23 15:21:21

  • [Lecture Notes in Electrical Engineering] Microelectronics, Electromagnetics and Telecommunications Volume 521 (Proceedings of the Fourth ICMEET 2018) || FSO-Based 5G Mobile Cellular Systems for Urban Canyons

    摘要： Over the last few years, there has been a rapid increase in the number of people who are using high data rate services and applications. To be able to support the ever-increasing data rates to the end users, the time has come to consider other technologies which use the upper parts of electromagnetic spectrum other than the Radio Frequency (RF) spectrum. One such technology which can be used as an alternative to RF is Free-Space optical (FSO) communications. It provides higher bandwidth and improved Bit Error Rate (BER) performance because of negligible multipath and fading effect. In this article, the performance of an RF system and an FSO system using BPSK-subcarrier intensity modulation (BPSK-SIM) in a weak turbulent atmosphere are compared. It is found that from simulation results, FSO system has a performance gain of 62% over RF for achieving a BER of 10?5.

    关键词： OWC,BER,FSO,BPSK-SIM

    更新于2025-09-23 15:21:21