Radio over fiber on gigabit passive optical network using QPSK modulation scheme

The main objectives of this paper is to improve knowledge of multimode fiber transmission over step-index plastic optical fiber SI POF with 1000 μm core. The thick SI POF fibers seem a very attractive alternative in local computer networks for the “classic” (thin) single- and multimode fibers because of their low price and easy installation. In the paper we show measurements of bandwidth and attenuation of various SI POF optical paths. In particular, there was investigated a cascade of passive components (couplers, patchcords) which can be part of transparent (passive) optical networks. Keywords : plastic optical fibre, passive optical network, multimode coupler. 1. INTRODUCTION Recently there has been publish a number of papers concerning optical data transfer over plastic optical fiber [1][2]. Both point-to-point and WDM passive network configurations are considered. The concept of passive network is well known as it comes to the access networks based on single mode fiber. Such networks were proposed in several standards (APON, BPON networks). Commercial solution have been developed and deployed since. We would like to extend benefits of this network type to home networks based on multimode optical fiber. We consider such networks as a viable solution of the optical home network architecture. Along with a multimode optical cable only multimode compatible elements (couples/splitters, connectors, etc.) may be used in the network. Once deployed the upgrade of such a network should be relatively easy. Unlike to the single mode PON where the bandwidth is not an issue, the multimode network maximum operational range is defined by the fiber bandwidth (related to the intermodal dispersion) rather than by the fiber attenuation [3]. The relation among the modal bandwidth of the fiber, the launching condition and mode coupling is fairly well known for silica GI optical fibers (

Fiber-to-the-home (FTTH) or close to it (FTTx) networks are poised to become the next major success story for optical fiber communications. Future FTTx access networks unleash the economic potential and societal benefit by opening up the first/last mile bandwidth bottleneck between bandwidth-hungry end-users and high-speed backbone networks. Owing to their longevity, low attenuation, and huge bandwidth, passive optical networks (PONs) are widely deployed to realize cost-effective FTTx access networks. Fiber has been envisioned for delivering broadband services for over 30 years. However, many roadblocks related to component and installation costs have slowed down the progress toward FTTx since it was first proposed. Currently, FTTH is being installed in many countries, but it still represents only a fraction of all deployed broadband lines (Shumate [2008]). The two major state-of-the-art PON standards IEEE 802.3ah Ethernet PON (EPON) and ITU-T G.984 Gigabit PON (GPON) consist both of a single upstream wavelength channel and a separate single downstream wavelength channel, whereby both channels are operated using time division multiplexing (TDM). EPON and GPON are expected to coexist for the foreseeable future as they evolve into next-generation PONs (NG-PONs) (Effenberger et al . [2007], Kazovsky et al . [2007]). NG-PONs can be categorized into high-speed TDM PON, wavelength division multiplexing (WDM) PON, and long-reach PON (LR-PON) (Lin [2008], Effenberger et al . [2009a]).

Broadband Passive Optical Access Networks

There is a rapidly increasing data flow between sensors and on-board processors in avionic platforms. Electro-optic (EO) sensors are moving to hyperspectral and radar to phased array to enable precision targeting, wide field of view surveillance and navigation. These trends call for next generation optical network technology which has to provide increasing high speed data transmission under harsh conditions. Recent developments go beyond simple point-to-point fiber links towards establishing optical distribution networks to deal with the data traffic [1]. A flexible and potentially low-cost implementation is the passive optical network (PON) which scales easily to increasing needs simply by upgrading the peripheral units without need to change the fiber connections and infrastructure. PONs are well established in the commercial access market with the increasing push to fiber-to-the-home (FTTH) technologies which has led to the development of a variety of low-cost devices for these networks. A key enabler in our development of an avionics PON is the reflective semiconductor optical amplifier (RSOA) which combines amplification and modulation into a single device [2]. The RSOA is a non-resonant device, thus wideband with the potential for ruggedness, especially high temperature operation with small or no need for cooling. At higher data rates up to 20 Gbps a related device, the reflective electro-absorption modulator with integrated amplification (R-SOA-EAM) can be used instead. To complete the adaptation we replaced the laser, commonly used to provide optical input power in a PON architecture with another non-resonant device, the superluminescent LED (SLED). To create upgrade flexibility we utilized wavelength division multiplexing (WDM) which allows addition and subtraction of channels without changing hardware. Coarse WDM (CWDM) was chosen over Dense WDM (DWDM) for two reasons: the large channel width (20nm) of CWDM reduces cost by relaxing fabrication tolerance and renders the use of temperature control unnecessary, thereby increasing reliability. The concept and current state of development of our optical network is described in this paper.

In this PhD dissertation multi-rate models are examined for the performance analysis of telecommunication networks through mathematical analysis and simulation. Particular emphasis is given to optical networks. The main goal is the development of analytical models for the calculation of network performance metrics, such as blocking probabilities, transmission delay and utilization of the common channel. The proposed analytical models are distinguished according to the network technologies. Three different technologies are considered: A) Wavelength routed optical networks. B) Optical access networks. C) Wireless Internet access networks. Multi-rate loss models are proposed for the performance evaluation of wavelength routed optical networks. Firstly, the case of a single link is considered and then a mesh all-optical network is examined. In addition, analytical models are proposed for Optical Packet Switching (OPS) networks, for the case of an all-optical OPS switch and of an OPS mesh network. Multi-rate analytical models are proposed for the evaluation of the performance of Passive Optical Networks (PONs) implementing different multiple access methods. For the case of Time Division Multiple Access (TDMA) the Ethernet PON is studied, which supports multiple service-classes. Regarding the Wavelength Division Multiplexing (WDM) PONs a hybrid WDM-TDMA PON is considered and the call-level performance is evaluated. Calls are distinguished by their arrival process, which can be random or quasi random, by their bandwidth requirements, which can be fixed of elastic and by their behavior during their service, which can be calls of fixed transmission rate or calls that alternate between ON and OFF periods. Finally multi-rate loss models are proposed for the case of Optical Code Division Multiple Access (OCDMA) PONs that take into account the user activity and the presence of additive noise in the transmission channel. For the performance analysis of wireless Internet access networks analytical models are proposed, which implement the IEEE 802.11 protocol or the IEEE 802.11e protocol. The proposed analysis calculated the saturation throughput and the end-to-end packet delay as a function of the Medium Access Control (MAC) delay and the queueing delay. In all cases the accuracy of the proposed models is validated through simulation.

In this paper, we have proposed an improved hybrid passive optical network model using wavelength division multiplexing (WDM) and time division multiplexing (TDM) with 96 users in the bidirectional optical fiber networks. The performance is evaluated based on different distances and modulation formats with the help of Q factor, BER and Eye diagram. In the proposed model, the data is successfully transmitted up-to a distance of 96 km with a data rate of 10 Gbits/sec. Comparative analysis of proposed models with respect to other four models are hence put forth.

Information and communication technology (ICT) has advanced significantly in the modern era, and the majority of smart technology utilized in smart cities are Internet of things (IoT) based. Hybrid passive optical networks (PON) consist of wavelength division multiplexing (WDM) and time division multiplexing (TDM) are of the most encouraging and widely utilized technologies in optical distribution networks (ODN) required for security, encryption data and bandwidth. The security of the mystery/private cryptographic key is crucial to the encryption process’s ability to secure data. Any strong encryption algorithm would be compromised by poor key management. In order to enhance the physical security, so as to protect the secret data during transmission across the channel and to ensure a secure exchange of the encryption key between the transmitter and the recipient, a hybrid system that incorporates cryptography, steganography, and key hiding techniques has been employed. To the best of our knowledge, Opti-System software with python devices combine to create a secure WDM/TDM-PON system depending on the Hill Group cipher and ITU-T G.989.2 standards. Simulation studies indicate that, a bidirectional fiber distance with a splitting ratio 1:64 and a symmetrical 40 Gbps can be accomplished successfully out at 60 km. The least amount of acceptable receiver sensitivity is −28.1 dBm for uplink (U/S) and −23.7 dBm for downlink (D/S).

Future passive optical networks (PONs) are expected to support much larger capacity and much wider coverage. How to jointly address these two design requirements represents one of the most challenging aspects in today’s research on PONs. So far, most research efforts have been devoted to devising new architectural or technological solutions to support such stringent requirements. In particular, the technology to be used for transmission may have diverse multiplexing techniques, types of transceivers, modulation formats, and detection techniques. However, the question of which transmission technology is the most effective considering the trade-offs in terms of complexity, offered capacity, and reach is still open. In this paper, we aim at answering this question comparing the use of time division multiplexing (TDM), wavelength division multiplexing (WDM), and hybrid TDM/WDM techniques in PONs. To achieve this goal, we first categorize the main options for transmission technologies in PONs in three families: colored dense WDM (DWDM), tunable DWDM, and colorless DWDM. Then, we propose a new optimization scheme that selects the optimal transmission technology for different operational scenarios that are defined by varying the number of users, the distance to the users, and the traffic load. The choice of the passive optical components to be used at the remote node is also part of the optimization scheme given its significant impact on the choice of the transmission technology. As a result, we report and discuss which transmission technologies are the most suitable under different operational scenarios.

Fiber To The Home (FTTH) is an infrastructure that provides a giant boost to the progress of technology driven applications, such as triple play, along with the required software and equipment for their implementation. It consists of an investment for the years to come that speeds development in more than one technological area and promotes overall growth. Nevertheless in a context of continuous effort for more cost effective and energy saving solutions, the need to invest in a structure that is free from excessive expenditure and at the same time is future-proof has become imperative. Deriving of this need, new technological solutions have begun to emerge and the tool for their financial evaluation could be proven of important value for optical network operators. This paper presents a techno-economic comparison of two different passive FTTH network technologies/architectures. The cases considered in this study are namely: i) metro ring in combination with gigabit passive optical networks (GPON) technology on the access part and ii) a new converged access-metro wavelength division multiplexing / time division multiplexing (WDM/TDM) passive optical network (PON) called: scalable advanced ring-based passive dense access network architecture (SARDANA). This work includes a quantitative modeling of the outside plant cost as well as of the active equipment cost of the two architectures. It is shown that the green solution of the PONs in combination with the expected energy savings guarantees a cost effective solution. Furthermore it is shown that the more elaborate design of the WDM/TDM PON provides a cost reduction of about 15% for densely populated areas and even greater for scarcely ones along with an ensured flexibility.

Gigabit-Passive Optical Network (GPON) is the key technology for today's PON. A hybrid GPON is a hybrid passive optical network, where WDM and TDM are integrated into a single passive optical network, with aims to increase both the cost effectiveness and link capacity. In this paper, 2.5-Gb/s hybrid WDM/TDM downstream link is presented, using RoF technique in the GPON network architecture. 8-DPSK modulation is utilized by using 2.4 GHz radio frequency. The simulation results show that signals are capable to propagate along 25 km standard SMF where up to 64 users are supported.

It has been recently experimentally and theoretically demonstrated that three nonlinear operation regimes can be observed in reflective semiconductor amplifiers in relation to gain saturation and, consequently, in relation to the bleaching of the modulation portion of the injected signal while the injected power increases. For moderately high-injected power, the modulation component of the signal is partially bleached, i.e., the extinction ratio (ER) is reduced. For higher input power, the modulation is exactly cancelled, i.e., the ER is almost 0 dB. Finally a further increase of injected power determines modulation inversion, with consequent eye re-opening. While the first two phenomena can be observed also in SOAs, though usually at higher injected power, the last regime is specific of RSOAs. In highly nonlinear RSOA the simultaneous presence of two waves, the incoming one and the reflected, which locally compete for gain along the device length, defines areas of strong depletion. The RSOA noise reduction capability, which has been widely exploited in passive optical networks (PON) topologies, is achieved by compressing the optical intensity fluctuations associated to the injected signal. This capability relies on the same mechanism governing gain saturation and modulation bleaching. Thus it is not surprising that the same nonlinear regimes observed in relation to gain saturation can be evidenced in relation to relative intensity noise (RIN) compression. In order to highlight this behavior and its consequences on PON design, we experimentally emulated a spectrum-sliced wavelength division multiplexing (WDM) PON topology. The impact on RIN of the injection into the RSOA and subsequent filtering actions operated by arrayed waveguide gratings (AWG) placed at the remote node and at the optical line terminal is evaluated both experimentally and by simulations. RIN measurements are performed in time domain exploiting a real time oscilloscope and in the spectral domain using an electrical spectrum analyzer in different point of the WDM PON topology to enlighten the different contributions to noise. Simulations have been also using an RSOA simple model, which has been realized with the commercial software, OptSim by RSOFT, and has been implemented by matching the data collected from the RSOA gain experimental characterization.

Next-generation optical access networks are envisioned to evolve into a converged, high-speed, multiservice platform supporting residential, business, mobile backhaul, and special purpose applications. Moreover, bandwidth demand projections suggest that terabit aggregate capacity may need to be reached in such next-generation passive optical networks (PON). To satisfy these requirements while leveraging the large investments made in existing fiber plants, a wavelength division multiplexed (WDM)-based long-reach PON architecture combined with a multiple access technology that features a passive last-mile split, large per-λ speeds, and statistical bandwidth multiplexing can be exploited. In this paper, the first terabit PON based on hybrid WDM orthogonal frequency division multiple access (OFDMA) technology is proposed and experimentally verified. To enable high-speed, long-reach transmission with simplified optical network unit (ONU)-side digital signal processing, multiband OFDMA with ONU-side sub-band selectivity is proposed. Design challenges and tradeoffs between analog and digital domain sub-band combining and selection are also discussed. Finally, the experimental setup and results of the first 1.2 Tb/s (1 Tb/s after overhead) symmetric WDM-OFDMA-PON over 90 km straight single-mode fiber and 1:32 passive split, featuring multiband OFDMA, digitally selective ONUs, and a coherent-receiver OLT are presented and analyzed. By supporting up to 800 ONUs with 1.25/10 Gb/s guaranteed/peak rates and exhibiting a record rate-distance product achieved in long-reach PON, the demonstrated architecture may be viewed as promising for future converged terabit optical metro/access.

Chapter 3 - Optical Technologies in Passive Optical Access Networks

In today's passive optical network, each optical network unit receives not only the data that belongs to its user but also the data of other users. This makes the network vulnerable to sniffing even though encryption has been done. To solve this problem, optical channels from an optical line terminal are switched directly to different user locations in such a way that the optical network unit receives only the data that belongs to its user. This paper exploits a mode-forming technique in an optical network of multi-mode fiber (MMF) using a commercially viable fiber coupler to optically route only the desired channel to the desired destination. We have successfully implemented a 2 x 2 mode-forming network, and the total channel coefficients related to each user are estimated at their locations. The feasibility of the proposed technique has been confirmed using a conventional graded-index MMF. The total channel matrix coefficients of this network are obtained by processing the transmitted training sequence in their user locations. A pre-multiple-input-multiple-output equalizer is implemented at the transmitter. The channels are successfully transmitted to their destinations, clarifying wavelength independence while maintaining data security to some extent. Furthermore, the exchange of channel in the output port is also supported by this network.

A passive optical network (PON) architecture based on a hybrid wavelength-division multiplexing (WDM) and time-division multiplexing (TDM) PON system with a remotely pumped erbium-doped fiber amplifier (EDFA) is presented as an excellent candidate for use in a next-generation optical access network. The remotely pumped EDFA operates as a bidirectional amplifier and provides a 15-dB gain to both upstream signals and seed light sources, so the sensitivity of upstream transmission is greatly improved. An upstream transmission of 1.25 Gb/s with a low seed channel power of -14 dBm is made feasible over a total reach of 25 km for 32-WDM channels and 16-TDM splits by the use of the remotely pumped EDFA. This scheme has advantages that it uses a single transmission fiber for both down-and up-stream signals and that it reduces the Rayleigh scattering contribution.