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Multimode fiber links can offer a useful approach for low cost and short Radio over Fiber (RoF) systems. However, in these connections the distortion effects are higher than in a singlemode fiber system. These effects can be compensated by a suitable optical receiver. In this paper an improved receiver structure is investigated for Radio over Multimode fiber systems. N-QAM radio signal transmission...
This article evaluates the performance of Wavelength Division Multiplex (WDM) networks considering two different modes of photonic Switching: Optical Packet Switching (OPS) and Optical Circuit Switching (OCS). A resource distribution planning is proposed including wavelength/amplifier allocation to improve the blocking probability and to ensure signal quality. The present study considered the effects...
In this paper, we examine a nation-wide deployment case study of 1024-way-split Long-Reach Passive Optical Network (LR-PON) for Ireland. We analyse the effect that different splitters configurations in the Distribution Section have on the PONs utilisation and on the total fibre cable length required to cover the country. Our approach, which considers both dense and sparsely populated areas, is based...
Cognition represents one of the ingredients to make up the future high-capacity heterogeneous optical networks. This paper provides three main contributions for a preliminary study of a Control and Management System (CMS) able to support the cognitive entity, named Cognitive Decision System (CDS). First of all, two architectural approaches to realize a cognitive optical network are presented. Secondly,...
In optical networks a group of logically distinct links can unintentionally share a physical resource (e.g, a cable or a duct). Such a group, called shared risk link group (SRLG), introduces a situation where a single failure of common resource can cause multiple failures. Failure of common resource usually occurs due to physical force (e.g, digging or earthquake) and causes failures of multiple links...
Passive Optical Networks (PONs) are attractive fiber-based access systems providing broadband access solutions at a low cost. A hybrid Wavelength Division Multiplexing (WDM) — Time Division Multiple Access (TDMA) PON is a favorite PON configuration, in which the researchers have drawn much attention. We have analysed and proposed several protocols for dynamic wavelength allocation in a WDM-TDMA PON,...
In the paper, an optical wireless link for point-to-point communication is analyzed. Its main focus is the analysis of the influence of various misalignments on the received power. Analysis includes influence of the tilt of the transmitter and the receiver as well as their mutual misalignment respecting the Gaussian intensity distribution of the transmitted beam in terms of geometrical optics. As...
This paper presents an analytical study on the performance of transmission control protocol (TCP) over free-space optical (FSO) links when the automatic-repeat request, selective repeat (ARQ-SR) scheme is used for the link layer. Using a three-dimensional (3-D) Markov model, we analytically derive the TCP throughput and energy-throughput efficiency, which is the the ratio between the TCP throughput...
Interleave-division multiple-access (IDMA) has been recently proposed as a new spread spectrum multiple-access technique in optical communication systems. However, IDMA has not been studied for intensity modulation/direct detection (IM/DD) optical networks. In this paper, we introduce modifications to traditional IDMA decoding algorithm so as to make it suitable for IM/DD optical communication systems...
Current data centers (DCs) networks rely on electronic switching and point-to-point interconnects. When considering future DC requirements, point-to-point interconnects will lead to poor network scalability and large power consumption. For this reason several optical switched interconnects for DCs have been recently proposed. However, the proposed optical switching solutions suffer from low flexibility...
Free space optical (FSO) communication links offer a number of advantages over radio frequency links. Main advantages of FSO communication links are electromagnetic compatibility, license-free band and high data rate. However, reliability of these links is highly dependent on atmospheric and weather conditions. An optical wave propagating through the atmospheric transmission media is very sensitive...
Two high-speed optical wireless demonstrators were produced within the EU funded framework 7 OMEGA project. One of these operates at 1.25Gbit/s demonstrating high data rates, and the other offering ‘room scale’ coverage at 280 Mbits/s. Details of design, implementation and testing of each are reviewed, together with the challenges of such systems and future directions for work in this area.
This study presents a wavelength division multiplexing multi-ring architecture for metropolitan area networks (MANs). An asynchronous transmission WDMA protocol is introduced that serves the variable size of Internet packets in nowadays ring MANs under asymmetric traffic scenarios. Especially, the proposed WDMA protocol takes under consideration the time sensitivity of Internet traffic and each time...
This paper presents the use of a digital signal processor (DSP) to implement an artificial neural network (ANN) equalizer in an organic light emitting diode (OLED) based visible light communications (VLC) system for the first time. The ANN is used to counteract the inter-symbol interference (ISI) experienced when the transmission rate exceeds the system modulation bandwidth. The link is made up of...
Single Carrier Decomposed-Quadrature Optical (SC-DQO) modulation has been suggested in the past, as a possible method for use in Optical Wireless (OW) Intensity Modulation with Direct Detection (IM-DD) communication systems. This method has lower peak-to-average power ratio (PAPR) when compared to Asymmetrically-Clipped Optical OFDM (ACO-OFDM). It was shown that its receiver utilizes only 50% of the...
A new design of photonic crystal fiber based on octagonal array of air holes in the silica background is proposed for using as a sensor node in the optical network protection system of gas pipelines. The aim of our design is achieving more sensitivity and lowering the confinement loss. In addition, introducing a hollow high index ring with an air hole in the center of fiber simultaneously enhances...
We report on the smallest Silicon Photonic modulator and lowest power Complementary Metal-Oxide-Semiconductor Mach-Zehnder Modulator (CMOS MZM) Driver for next generation Coherent Transceivers. Bit-Error-Ratio (BER) characterization of this device demonstrates comparable performance relative to a commercial Lithium Niobate (LN) modulator and capability of highperformance transmission for long-haul...
Free-space optical (FSO) and microwave telecommunication links have considerably adverse propagation characteristics. For radio waves that are operating in the millimeter wavelength one of the most harmful circumstantial factors is the attenuation caused by precipitation, especially by rain. However, for FSO links the main adverse effect is fog, being most responsible for the unavailability of FSO...
In this paper it is proposed and designed an original all-optical Encoder (o-Encoder) intended, but not exclusively, to be part of future optical digitising radio-over-fibre (o-DRoF) transceiver. It is based on the Semiconductor Laser Amplifier Loop Mirror (SLALOM) configuration exploiting the nonlinearities of a semiconductor optical amplifier (SOA) in cross-switching regime. The proof-of-principle...
We have proposed a hybrid lattice photonic crystal fiber using two different sized air holes and conventional square and triangular lattice cladding structure. Based on the plane wave expansion method and finite element method, we numerically investigated polarization, dispersion and confinement loss of the hybrid square and triangular lattice photonic crystal fiber and compared the properties of...
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