Review and comparative assessment of FDMA-PON vs. TDMA-PON for next-generation optical access networks

We present in this paper a comparative assessment of Time Division Multiple Access Passive Optical Networks (TDMA-PON) and Frequency-Division Multiple Access Passive Optical Networks (FDMA-PON). We try to point out the pros and cons of the two different approaches in the context of very high capacity next-generation PON mainly in terms of physical layer transmission performances, but also introducing some comparison in terms of complexity, cost and power consumption

Integration of Hybrid Passive Optical Networks (PON) with Radio over Fiber (RoF)

A cost effective, robust, and high capacity access network necessitated to meet the mounting customer demands for bandwidth-desirous services. A remarkable evolution of access networks is observed both in wired and wireless, predominantly driven by ever-changing bandwidth requirements. A wireless connection releases the end user from the restrictions of a physical link to a network that results in mobility, flexibleness, and ease of use. Whereas, optical networks offer immense amount of bandwidth that appease the most bandwidth voracious customers compared to bandwidth limited wireless networks. The integration of wired and wireless domains in the access landscape that presents a technical analysis of optical architectures suitable to support radio over fiber (RoF) is the objective of this chapter. Investigate the main trends that drive the merger of fiber and wireless technologies in access networks. Moreover, study the primary terms and the particular transmission features of integrated fiber-radio links to form a well-defined classification of hybrid systems and techniques. This work also recognizes the major problems for realization of RoF systems and examines the limitation, advantages, and diversity of integrated RoF-PON technology

Mecanismos de tuning em redes de acesso óticas

Mestrado em Engenharia Electrónica e TelecomunicaçõesO principal tema abordado neste trabalho e a tecnologia a ser utilizada em redes passivas oticas de nova gera c~ao, nomeadamente o TWDM e o PtP WDM, com um foco em especial nos mecanismos de tunabilidade a ser usados nas arquiteturas de rede mencionadas. Come cou por ser feita uma abordagem geral ao tema, um "overview" a recomenda c~ao para o NG-PON2 e apresentada, assim como uma revis~ao a transceivers incolores, componentes essenciais nas arquitecturas do NG-PON2. Tendo em conta o n vel de precis~ao apresentada, tr^es tipos de ONUs s~ao de nidas nos standards do NG-PON2, e os mecanismos de tuning necess arios para lidar com os diferentes tipos de ONU s~ao tamb em apresentados. Foi caracterizado um laser sintoniz avel (DFB) tendo em vista a sua utiliza c~ao numa ONU do NG-PON2, os parametros avaliados foram: tempo de sintoniza c~ao, excurs~ao espectral e precis~ao de tuning. As t ecnicas de medi c~ao s~ao apresentadas bem como os resultados obtidos.The main issue addressed in this work are the technologies to be employed in the next-generation passive optical networks, including TWDM-PON and PtP WDM, with a particularly focus on the tuning mechanisms featuring the aforementioned network architectures. A general approach to the topics was carried out, by making an overview the NG-PON2 recommendation, a review to colorless transceivers is presented as well, essential components on the NG-PON2 architectures. Three types of ONUs are de ned in NGPON2 standards, by taking into account the accuracy level of the ONU Tx, tuning mechanisms necessary to to deal with the di erent kind of ONUs are presented as well A tunable DFB laser was characterized, considering its utilization on a NGPON2 ONU. The evaluated parameters are: tuning time, spectral excursion and tuning accuracy. The setups utilized for the measurements are presented as well as the results

Optical frequency comb source for next generation access networks

The exponential growth of converged telecommunication services and the increasing demands for video rich multimedia applications have triggered the vast development of optical access technology to resolve the capacity bottleneck at metropolitan-access aggregations. To further enhance overall performance, next generation optical access networks will require highly efficient wavelength division multiplexing (WDM) technology beyond the capability of current standard time division multiplexed (TDM) systems. The successful implementation of future-proof WDM access networks depends on advancements in high performance transmission schemes as well as economical and practical electronic/photonic devices. This thesis focuses on an investigation of the use of optical frequency comb sources, and spectrally efficient modulation formats, in high capacity WDM based optical access networks. A novel injected gain switched comb generation technique which deliver simplicity, reliability, and cost effectiveness has been proposed and verified through experimental work. In addition, a detailed characterization of the optical comb source has been undertaken with special attention on the phase noise property of the comb lines. The potential of the injected gain switched comb source is then demonstrated in a digital coherent receiver based long reach WDM access scenario, which intends to facilitate 10 - 40 Gbit/s data delivery per channel . Furthermore, an optical scalar transmission scheme enabling the direct detection of higher order modulation format signals has been proposed and experimentally investigated

Wavelength reconfigurability for next generation optical access networks

Next generation optical access networks should not only increase the capacity but also be able to redistribute the capacity on the fly in order to manage larger variations in traffic patterns. Wavelength reconfigurability is the instrument to enable such capability of network-wide bandwidth redistribution since it allows dynamic sharing of both wavelengths and timeslots in WDM-TDM optical access networks. However, reconfigurability typically requires tunable lasers and tunable filters at the user side, resulting in cost-prohibitive optical network units (ONU). In this dissertation, I propose a novel concept named cyclic-linked flexibility to address the cost-prohibitive problem. By using the cyclic-linked flexibility, the ONU needs to switch only within a subset of two pre-planned wavelengths, however, the cyclic-linked structure of wavelengths allows free bandwidth to be shifted to any wavelength by a rearrangement process. Rearrangement algorithm are developed to demonstrate that the cyclic-linked flexibility performs close to the fully flexible network in terms of blocking probability, packet delay, and packet loss. Furthermore, the evaluation shows that the rearrangement process has a minimum impact to in-service ONUs. To realize the cyclic-linked flexibility, a family of four physical architectures is proposed. PRO-Access architecture is suitable for new deployments and disruptive upgrades in which the network reach is not longer than 20 km. WCL-Access architecture is suitable for metro-access merger with the reach up to 100 km. PSB-Access architecture is suitable to implement directly on power-splitter-based PON deployments, which allows coexistence with current technologies. The cyclically-linked protection architecture can be used with current and future PON standards when network protection is required

Fibre Optic Parametric Amplifiers For Transient Limited Optical Fibre Systems

The thesis explores fibre optical parametric amplifiers (FOPAs) to implement and develop the FOPA ability to provide transient free burst mode signal amplification, presenting potential applications in reach extended access networks and time-varying optical transmission systems. This document experimentally demonstrates FOPA as a potential drop-in amplifier candidate for transient limited optical systems by experimentally investigating and comparing transient effects in conventional fibre amplifiers. For example, future reach extended optical access networks. Additionally, this work provides evidence for transient free burst traffic amplification enabled by FOPA. A number of experimental techniques were implemented to demonstrate an ultra- fast response, high burst signal gain, and the ability to simultaneously amplify bi- directionally transmitted signals in a dual telecom band. Novel polarisation-insensitive FOPA employed in a 50 km reach extended access network link to achieve clean burst mode signal amplification. PI-FOPA targeted varied burst durations and burst traffic density amplification to evaluate performance compared to a commercial erbium-doped fibre amplifier (EDFA) and a discrete Raman amplifier. FOPA enhances link receiver sensitivity by >3 dB compared to EDFA and Raman amplifier for a varied burst duration amplification from 70 µs to 5 µs. For high burst traffic density amplification from 5% to 97%, FOPA allows burst traffic amplification up to 97% traffic, while EDFA and discrete Raman amplifier traffic density amplification was limited to 15% and 30%. We first presented a bi-directional non- burst and burst signal amplification by implementing a novel dual-band FOPA setup. FOPA achieved polarisation insensitive net gain of >16 dB for >50 nm apart signals in C and L bands. FOPA's ability to provide a wide broadband gain of ~10THz is utilized to amplify a non-burst and bursty signal in a dual-band transmission with a single in-line PI-FOPA amplifier simultaneously

Burst-mode electronic dispersion compensation in long reach PONs

Long reach passive optical networks (LR-PONs), which integrate fibre-to-the-home with metro networks, have been the subject of intensive research in recent years and are considered one of the most promising candidates for the next generation of optical access networks. Such systems ideally have reaches greater than 100km and bit rates of at least 10Gb/s per wavelength in the downstream and upstream directions. Due to the limited equipment sharing that is possible in access networks, the laser transmitters in the terminal units, which are usually the most expensive components, must be as cheap as possible. However, the requirement for low cost is generally incompatible with the need for a transmitter chirp characteristic that is optimised for such long reaches at 10Gb/s, and hence dispersion compensation is required. In this thesis electronic dispersion compensation (EDC) techniques are employed to increase the chromatic dispersion tolerance and to enhance the system performance at the expense of moderate additional implementation complexity. In order to use such EDC in LR-PON architectures, a number of challenges associated with the burst-mode nature of the upstream link need to be overcome. In particular, the EDC must be made adaptive from one burst to the next (burst-mode EDC, or BM-EDC) in time scales on the order of tens to hundreds of nanoseconds. Burst-mode operation of EDC has received little attention to date. The main objective of this thesis is to demonstrate the feasibility of such a concept and to identify the key BM-EDC design parameters required for applications in a 10Gb/s burst-mode link. This is achieved through a combination of simulations and transmission experiments utilising off-line data processing. The research shows that burst-to-burst adaptation can in principle be implemented efficiently, opening the possibility of low overhead, adaptive EDC-enabled burst-mode systems