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In this paper, we newly propose and theoretically analyze the performance of all-optical amplify-and-forward (OAF) relaying free-space optical (FSO) systems using erbium-doped fiber amplifier (EDFA) combined with optical hard-limiter (OHL) over atmospheric turbulence channels. The use of OHL enables OAF relaying FSO systems to remove accumulated background noise, which is one of the main factors that...
This paper proposes a cost-effective, scalable network architecture, which combines millimeter-wave (MMW) and free space optics (FSO) technologies that can be employed as a complementary solution for pre-deployed optical fiber based 5G cellular backhaul networks.
Free-space optical communication (FSO) is a line-of-sight (LOS) technology that enables data transmission based on the propagation of light in free space. Compared to radio frequency (RF) communication systems, FSO ones provide high data rates, unregulated bandwidth, high security, and low power. Therefore, FSO systems are rapidly gaining interest as an effective means of transferring data at high...
In this paper, we propose to use spatial pulse position modulation (SPPM), which is the combination of optical spatial modulation (SM) and pulse position modulation (PPM), as a powerful technique to improve the performance of free-space optical communication (FSO) systems. We analyze the performance of proposed system taking into account most major effects of FSO channel including geometric spreading...
Multihop free space optical (FSO) system using optical amplify-and-forward (OAF) relaying technique combined with wavelength division multiplexing (WDM) is proposed for all-optical access networks. The proposed system can provide a low cost, flexible, and high-bandwidth access network for multiple users. To investigate the system performance, we consider a special case of dual-hop WDM-FSO system taking...
In this paper, we propose to use relay transmission as a powerful technique for performance improvement of free-space optical code-division multiple-access (FSO/CDMA) systems. Relay nodes are based on chip detect-and-forward to avoid decoding process that makes the relay nodes more complex. We formulate a closed-form expression for bit-error rate (BER) of proposed FSO/CDMA systems over log-normal...
This paper analytically study the performance of amply-and-forward (AF) serial relaying free-space optical (FSO) systems employing avalanche photodiodes (APD) in atmospheric turbulence modelled by the Gamma-Gamma distribution. The subcarrier binary phase-shift keying (SC-BPSK) signalling is assumed and at each relay node, an APD is used for signal detection and amplification. Closed-form expressions...
Strong atmospheric turbulence and pointing errors are major challenges in free-space optical communication (FSO) systems. In this paper, in order to overcome these challenges, we propose to employ multi-hop transmission with single-input multiple-output (SIMO) links (i.e., receiver diversity) in FSO systems. In addition, M-ary pulse-position modulation (PPM) and symbol detect-and-forward relaying...
In this paper, we analyze the performance of all-optical dual-hop free-space optical communication (FSO) systems over strong atmospheric turbulence channels. In our analysis, turbulence channels are modeled by Gamma-Gamma distribution and dual-hop transmission is based on optical amplify-and-forward (OAF) technique. We formulate both exact-form and closed-form expressions for bit-error rate (BER)...
In this paper, we analyze the performance of multihop free-space optical communication (FSO) systems over strong turbulence fading channels together with misalignment (pointing error) effects. The analysis is carried out under the assumption that turbulence channels are modeled by Gamma-Gamma distribution and multihop transmission is based on symbol decode-and-forward relays. We formulate a closed-form...
We theoretically analyze the performance of free-space optical (FSO) systems using rectangular quadrature-amplitude modulation (QAM) and an avalanche photodiode (APD) receiver over atmospheric turbulence channels. Both log-normal and gamma-gamma channel models are used in the analysis for the cases of weak/moderate and strong atmospheric turbulence. The system bit error rate, when Gray code mapping...
In this paper, we propose a novel access protocol for optical burst switching (OBS)-ring networks. The proposed access protocol is based on the scheme of locating idle time slot at all wavelengths before sending bursts. This would help to avoid burst collision and efficiently use wavelength resource. To support this access protocol, a low-cost node architecture that provides burst transmission on...
We theoretically analyze the performance of free-space optical (FSO) communication systems using rectangular quadrature amplitude modulation (QAM) and avalanche photodiode (APD) over atmospheric turbulence channels. The log-normal fading channel is used in the analysis. We derive the system's average symbol error rate (SER) taking into account the APD shot noise and thermal noise, turbulence strengths,...
In this paper, we propose a model of Long-reach Passive Optical Network (LR-PON) using multi-wavelength optical code-division multiplexing (OCDM) and Erbium-doped fiber amplifier (EDFA). In addition, we analyze the effects of EDFA noise on the performance of OCDM-based LR-PON. Other noise and interference such as shot noise, thermal noise, beat noise, and multiple-access interference (MAI) are included...
In this paper, a model of Gaussian pulse propagation over atmospheric turbulence channel is used to comprehensively analyze the performance of PPM-based free-space optical communication (FSO) systems with APD receiver. This model simultaneously takes into account all effects of atmospheric turbulence including intensity fluctuation and pulse broadening, which has not been considered in previous works...
In this paper, we present a comprehensive study of the effects of atmospheric turbulence, including intensity fluctuation and pulse broadening, on the performance of FSO/CDMA systems. A realistic model of Gaussian pulse propagation is used for analyzing the bit error rate (BER). The numerical results show that pulse position modulation (PPM) with high modulation level should not be used for FSO/CDMA...
In Optical Burst Switching (OBS) networks, Just-in-Time (JIT) is a simple resource reservation scheme, which does not involve complex scheduling and is amenable to hardware implementation. However, in OBS networks using JIT, the header processing time is a main factor that affects the network performance since it is included in resource reservation time. In this paper, we propose a novel optical code...
In OCDMA systems, pulse position modulation (PPM) and multi-code modulation (MCM) have been proven as efficient methods for respectively mitigating multiple access interference (MAI) and dispersion. In this paper, we propose to combine PPM and MCM to create a novel modulation scheme, multi-code pulse position modulation (MCPPM). We then theoretically analyze the performance of the 2-D OCDMA system...
The standard core GMPLS networks consist of two layers, Fiber Switch Capable (FSC) and Wavelength Switch Capable (LSC). To extend the core switch capacity, code switch capable (CSC) layer has been added. The CSC layer, however, induces the complexity of the networks. In this paper, we propose a novel scheme of two-dimensional (2-D) optical code label for core GMPLS networks. In our proposal, the LSC...
A new modulation scheme for 2-D OCDMA systems named multi-code modulation (MCM) is proposed in this paper. The key advantage of MCM over the conventional ones is the ability of mitigating simultaneously both multiple access interference and dispersion. We also propose to combine MCM with heterodyne detection, a powerful technique to relax optical beating interference, to obtain better performance...
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