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In this article, the performance of grey-coded advanced optical modulation formats is evaluated on a single-channel high-speed long-haul optical communication link and is compared to the respective differential-coded modulation formats. Polarisation division multiplexed optical in-phase quadrature modulator (IQM) structure, and homodyne detection s...
Citations
... For instance, core networks can transmit about 80 channels by compressing the channels and spacing them 50 GHz apart. In order to build a fixed grid network, 50 GHz channel spacing is used to transmit different bitrates of 100 Gbps [5]. ...
The best cost-effective method of lowering the cost per transmitted bit is an increase in transmission symbol rate as well as the order of quadrature amplitude modulation. Specifically,
upcoming transponders aim to accommodate data rates up to 1 Tb/s using super-channels due to the bandwidth limitations of electrical components.Throughput can also be increased by a flexible-grid architecture by closing spectral gaps in the available optical spectrum. The distance and transmission module is introduced in the work; it chooses the appropriate modulation depending on the distance. Specifically, a 1 Tbps super-channel with four subcarriers, each one modulated with PM-32QAM at a Baud rate of 33 G-Bd per carrier, has been used. By using the Nyquist filter, the subcarrier spacing for PM-32QAM has been set to 37.5 GHz, which enables 32 × 1.0 Tbps super-channels overall over C-band and could lead to a 32.0 Tb/s C-band capacity. For PM-32 QAM,which is observed, the required optical signal-to-noise ratio at the forward error correction threshold is 5.4 dB. Erbium-Doped Fibre Amplified (EDFA) Single Mode Fiber has been used to achieve a transmission range of 750 km for PM-32 QAM modulated super-channels.
... The single photodiode (SPD) detection technique is investigated in this work for a trade-off between the LED and the CW laser. The wavelength spectrum in the case of SAC is divided into bins similar to the spectral code allocated to certain subscribers [24]. The data in a CCIS design is not distributed across the LED and laser wavelengths. ...
... In fact, the split LED spectrum and laser carry the same data bits and are used as a code sequence. For example, the pseudorandom binary sequence (PRBS) of user#1 is coded with the DPS code sequence "100010010100" [11] via The wavelength spectrum in the case of SAC is divided into bins similar to the spectral code allocated to certain subscribers [24]. The data in a CCIS design is not distributed across the LED and laser wavelengths. ...
... As a future technology, CCIS design implementation could be considered feasible. Low-priced broadband sources that are incoherent (i.e., ASE and LEDs) with the incorporation of simple optical filters for wavelength assignment make them applicable for SAC [24,25]. Similarly, the power output of a CW laser does not change over an averaged period, and large frequency power variations with minimum effect in any class of applications tend to make it an efficient source but a costly option [23]. ...
This paper is devoted to evaluating the combined coherent and incoherent sources (CCIS) technique for different applications in the optical domain and future optical code division multiple access (OCDMA) networks. Spectral amplitude coding (SAC) has gained significant attention in optical processing systems due to its increased capabilities in dealing with multiple-access interference (MAI) efficiently. Fixed right shift (FRS) is adopted as a signature code in this study. Furthermore, performance analysis is studied in terms of bit error rate (BER) for the system using CCIS in both the free space optics (FSO) and sky mesh network using an aerial altitude platform system (AAPS). Simulation results confirmed that a CCIS design significantly improves system performance with moderate cost. An acceptable BER value of 10−9 at 1.25 Gbps data rate and 60 km, 38 km, and 6 km distances for the laser, CCIS, and LED sources, respectively, can be supported. In particular, at Q-factor ~4.5, the FSO ranges under low haze, moderate haze, and heavy haze are, respectively, 3.7 km, 2.5 km, and 1.5 km. The reason is that a CCIS design causes an increase in the effective transmitted power. It can be summarized that a CCIS design can provide reliable solutions and an affordable cost for future optical fiber and wireless network applications.
... Tables 2, 3 show haze levels with their attenuations and fog levels with their attenuations, respectively [34]. ...
... Rain level with attenuation [32].TABLE 2 | Haze level with attenuation[34]. ...
... Fog level with attenuation[34]. ...
A novel free space optics (FSO) system is introduced in this article by combining orthogonal frequency division multiplexing (OFDM) with spectral amplitude coding optical code division multiple access (SAC-OCDMA) to be implemented in 5G technology and smart cities. Enhanced double-weight (EDW) codes are used as signature codes, while for the detection technique, single photodiode detection (SPD)
is applied for the SAC-OCDMA system. OFDM with a four-quadrature amplitude modulation (4-QAM) scheme is assigned to the three users in the SAC-OCDMA system, each carrying 15 Gbps. Adverse weather conditions, such as clear, fog, haze, rain, and dust storm, that affect the FSO channel are considered. The performance of the proposed system is evaluated in terms of log of bit error rate and received power at different propagation distances. The simulation results show successful transmission of 3 × 15 Gbps with a propagation range of 3.45 km under clear air and 1.316, 1.045, and 0.7 km under rain conditions (light, medium, and heavy rain) with a received power of −12.6 dBm. As for haze conditions, the range and received power are 2.391 km with −13 dBm for low haze, 1.591 km with −12.7 dBm for medium haze, and 1.025 km with −12.6 dBm for heavy haze. The range is reduced and becomes 1.085, 0.784, and 0.645 km under fog conditions (light, medium, and heavy fog) with −12.6 dBm received power. Furthermore, the system achieved a range of 0.681, 0.232, and
0.102 km under dust conditions (light, medium, and heavy dust) with a received power of −16 dBm.
... The spectral efficiency is also enhanced by the utilization of advanced modulation formats in transmission systems. 3,4 In multiple access scheme, a large number of geographically separated users share a common channel for transmitting and receiving signals. 5,6 The orthogonal multiple access (OMA) techniques, such as time-division multiple access (TDMA), frequency-division multiple access (FDMA), code-division multiple access (CDMA), and polarization division multiplexing, are used in past to meet the demand of high-capacity data transmission. ...
... The unprecedented Covid-19 situation across the globe has compelled people to live with new norms of life. In this scenario, most people work from home; this needs a seamless, uninterrupted, efficient, robust, cost-effective, huge scale of photonic integrated circuits (PICs) and optical fiber-wireless communication infrastructures [1][2][3]. Moreover, high-definition television (HDTV) distribution, online network games, interactive multimedia services, HD virtual reality (VR), online classes for academic purpose, webinars through online platforms like zoom and google classroom have been presently in use to an extent like never before [4][5][6]. ...
After thorough optical characterization of the indium-tin-oxide (ITO)-plasmonic material, a V-shaped ITO based highly efficient electro-absorption modulator (EAM) is designed, simulated, and proposed with 220 nm and 350 nm waveguide height to meet the explosive demand for miniature photonic integrated circuits (PICs) and high-speed optical communication systems. Comsol Multiphysics-based rigorous finite-element-method (FEM) is used for optimizing the geometrical structure of the EAMs, i.e. V-shape and various dimensions for 1550 nm operating wavelength supporting single mode transverse magnetic (TM) polarized light. The simulated results of the V-shaped ITO-plasmonic
material based EAMs show an enhanced performance as compared to most of the contemporary ITO based EAMs regarding insertion loss (IL) ≈ 0.031 dB/µm and 0.025 dB/µm, extinction ratio (ER) ≈ 7.02 dB/µm and 11.04 dB/µm, figure-of-merit (FOM) ≈ 226 and 441, for the EAMs with 220 nm and 350 nm waveguide height, respectively. These results are significant for the fabrication of next-generation photonic integrated circuits.
... Each independent stream is directed towards a multi-level Quadrature Amplitude Modulation (M-ary QAM) generator block which encodes the data in two quadrature phase. In this work, different bit rates are adopted for different modulation schemes as per the work reported in [24]. Here, PDM and CO-OFDM techniques are used to realize 4-QAM, 16-QAM, 32-QAM, and 64-QAM signals at 100 Gbps (25 Gbaud), 120 Gbps (15 Gbaud), 360 Gbps (36 Gbaud), and 480 Gbps (40 Gbaud) transmission rates, respectively. ...
... Link parameters[24,30,31]. ...
The reliability and efficiency of free space optics (FSO) systems is significantly degraded by attenuation caused by different climate conditions and atmospheric turbulence. In this work, an FSO transmission system with high-speed transmission capability is proposed by deploying orthogonal frequency division multiplexing (OFDM) to mitigate channel fading effects. Further, we propose the hybridization of polarization division multiplexing (PDM) with CO-OFDM to improve the system capacity. We perform the bit error rate (BER) and optical signal to noise ratio (OSNR) comparative analysis of multi-level quadrature amplitude modulation (QAM) schemes, i.e., 4-QAM, 16-QAM, 32-QAM, and 64-QAM at 100, 120, 360, and 480 Gbps transmission rates, respectively. The obtained results reveal that the 4-QAM modulation scheme achieves the highest transmission range and the least OSNR requirement. In terms of spectral efficiency, 64-QAM shows the best performance. Also, the impact of different climate conditions on the system performance has been investigated. Through simulations, we demonstrate a successful transmission of 100 Gbps 4-QAM information at 15 km. Furthermore, we numerically investigated the increasing scintillation effect on the BER system performance. The proposed system not only reduces the channel fading but also improves the information rate and maximum transmission distance. The reported work can be considered for future FSO systems even in adverse climate conditions.
... As dispersion also causes power loss for the system, DSP techniques which provide power efficiency [16] can enable high data rates for such cases. DP-QPSK has been shown to provide high data rates with the use of dispersion compensation fiber and DSP techniques [17]. DSP techniques are a powerful tool to compensate optical fiber transmission impairments in single carrier systems as shown by many researchers to achieve high capacity and error-free transmission. ...
... Figures 12(a) to 12(d) explain that the constellation of the proposed model is much improved by using the qualified receiver than DCF or conventional DSP receiver for the DP-QPSK-based FOCS. Table 2 presents a comparison of performance for the presented work with two other relevant work [17,18] based on DP-QPSK modulation-supported FOCS. Table 2 mentions the improvement in receiver sensitivity (as shown in Figure 10) with a very low BER as compared with the recently presented work on DP-QPSK. ...
Fiber optic communication systems (FOCSs) have attained a lot of attention by revolutionizing the
telecommunication industry and offering new possibilities with the technical advancements in state-ofthe-art high speed digital electronics. Advanced modulation formats make use of the phase, amplitude
and polarization of the optical signals at the same time to provide high spectral efficiency as compared to
1 bit/s/Hz for intensity modulation direct detection system (IMDD), but are highly prone to transmission
impairments. Thus, the effects that add up to the optical fiber impairments such as optical fiber chromatic
dispersion (OFCD), polarization model dispersion (PMD), and phase offset and noise (POaN) needs to
be addressed at the receiver side. The development of components and algorithms to minimize these
effects in next generation FOCSs with 100 Gbps data rate and beyond with long-haul transmission, is
still a challenging issue. In this paper, digital signal processing (DSP) assisted dispersion and non-linear
compensation techniques are presented to compensate for physical layer impairments including OFCD,
PMD and POaN. The simulations are performed considering Dual Polarization (DP)-QPSK modulation
format to achieve two-fold data rate to achieve spectral efficiency of 3.28 bits/s/Hz by making use
of the polarization diversity and system performance is investigated in terms of bit error rate (BER),
constellation diagrams and quality factor (Q-factor) for different values of optical signal-to-noise ratio
(OSNR), launch power (P
L
) and fiber length
في هذا البحث تم اقتراح نظام تجميع بتقسيم الطول الموجي وتقسيم الاستقطاب باستخدام التعديل 16-QAM، مع تطبيق ترميز غراي في المرسل وتطبيق في طرف الاستقبال الكشف المترابط ومعالجة الإشارة الرقمية لتعويض ضجيج الطور واللاخطية مع التشتت اللوني وتشتت نمط الاستقطاب، وذلك لتحسين الأداء ويتيح فعالية طيفية عالية مع إمكانية الإرسال بمعدلات عالية. أجريت المحاكاة باستخدام بيئة Optisystem وتم تقييم الأداء باستخدام أهم مقاييس الأنظمة الضوئية: الفعالية الطيفية وسعة الإرسال بالإضافة إلى معاملات Q-factor وBER وOSNR. حيث تم تصميم نظام WDM-PDM 16-QAM ذو ثمان أقنية معدل كل قناة 10 Gb/s وبمعدل إجمالي 80 Gb/s، وتباعد بين القنوات مقداره 25GHz مما سمح بالوصول لفعالية طيفية ضوئية أكبر من 4b/HZ، مع اختبار الأداء من أجل مسافة 250 Km. وتمت مقارنة أداء النظام عند استخدام ترميز غراي والترميز التفاضلي، حيث يظهر ترميز غراي المستخدم في أجهزة الإرسال أداءً أفضل مقارنةً بالترميز التفاضلي.
Free space optics (FSO) communication systems are preferred due to their high transmission capacity so it can support the ever-increasing volume of online traffic. Optical code division
multiple access (OCDMA) is ideal for enhancing capacity by utilizing the same wavelengths for different information transmission. This paper presents a new FSO system based on the combination
of orthogonal frequency division multiplexing (OFDM) and OCDMA systems. Three OCDMA
channels, employing diagonal permutation shift (DPS) codes, carry 20 Gbps each, modulated by
4-level quadrature amplitude modulation (QAM) and OFDM. To assess performance, the proposed system considers severe climate conditions like rain, fog, and snow. The effectiveness is measured by bit error rate (BER) and received optical power (ROP). In addition, actual meteorological
data for the cities of Alexandria, Egypt and Pune, India are evaluated to demonstrate the applicability of the proposed model in a real-world setting. The results reveal successful transmission with an overall capacity of 60 Gbps over a 3600 m FSO range in Alexandria, achieving a 0.27 dBm ROP.
In Pune, with higher average rainfall, the maximum FSO link is 2750 m with a -0.06 ROP. Furthermore, the proposed model can propagate up to 850 m under weak turbulence (WT).
