Impact of Fiber Duplication on Protection Architectures Feasibility for Passive Optical Networks

Adaptability of high capacity passive optical network (PON) requires the provision of an efficient fault detection and restoration mechanism throughout the network at an acceptable cost. The readily adapted pre-planned protection strategy relies on component duplication, which significantly increases the cost of deployment for PON. Therefore, it is imperative to determine a suitable component that requires high redundancy and determine the impact of protection for that component on feasibility of PON. Five protection architecture including ITU-T 983.1 Type C, single ring, dual ring, tree- and ring-based architectures with hybrid star-ring topology at the optical distribution network (ODN), are considered to evaluate the impact of fiber duplication in terms of capital expenditure (CAPEX), operation expenditure (OPEX), reliability, and support for maximum number of subscribers. Reliability block diagram (RBD) based analysis shows that desirable 5 nines connection availability is provided by each protection architecture and utilization of ring topology avoids duplication of the fiber but effects the number of subscribers. Furthermore, it is observed that OF duplication at ODN is the main contributor to CAPEX. Collectively hybrid protection architectures provide efficient performance and proves to be a feasible solution for the deployment of survivable PONs at the access domain

Optimization in Telecommunication Networks

Network design and network synthesis have been the classical optimization problems intelecommunication for a long time. In the recent past, there have been many technologicaldevelopments such as digitization of information, optical networks, internet, and wirelessnetworks. These developments have led to a series of new optimization problems. Thismanuscript gives an overview of the developments in solving both classical and moderntelecom optimization problems.We start with a short historical overview of the technological developments. Then,the classical (still actual) network design and synthesis problems are described with anemphasis on the latest developments on modelling and solving them. Classical results suchas Menger’s disjoint paths theorem, and Ford-Fulkerson’s max-flow-min-cut theorem, butalso Gomory-Hu trees and the Okamura-Seymour cut-condition, will be related to themodels described. Finally, we describe recent optimization problems such as routing andwavelength assignment, and grooming in optical networks.operations research and management science;

Survivable mesh-network design & optimization to support multiple QoP service classes

Every second, vast amounts of data are transferred over communication systems around the world, and as a result, the demands on optical infrastructures are extending beyond the traditional, ring-based architecture. The range of content and services available from the Internet is increasing, and network operations are constantly under pressure to expand their optical networks in order to keep pace with the ever increasing demand for higher speed and more reliable links

Survivable multicasting in WDM optical networks

Opportunities abound in the global content delivery service market and it is here that multicasting is proving to be a powerful feature. In WDM networks, optical splitting is widely used to achieve multicasting. It removes the complications of optical-electronic-optical conversions [1]. Several multicasting algorithms have been proposed in the literature for building light trees. As the amount of fiber deployment increases in networks, the risk of losing large volumes of data traffic due to a fiber span cut or due to node failure also increases. In this thesis we propose heuristic schemes to make the primary multicast trees resilient to network impairments. We consider single link failures only, as they are the most common cause of service disruptions. Thus our heuristics make the primary multicast session survivable against single link failures by offering alternate multicast trees. We propose three algorithms for recovering from the failures with proactive methodologies and two algorithms for recovering from failures by reactive methodologies. We introduce the new and novel concept of critical subtree. Through our new approach the proactive and reactive approaches can be amalgamated together using a criticality threshold to provide recovery to the primary multicast tree. By varying the criticality threshold we can control the amount of protection and reaction that will be used for recovery. The performance of these five algorithms is studied in combinations and in standalone modes. The input multicast trees to all of these recovery heuristics come from a previous work on designing power efficient multicast algorithms for WDM optical networks [1]. Measurement of the power levels at receiving nodes is indeed indicative of the power efficiency of these recovery algorithms. Other parameters that are considered for the evaluation of the algorithms are network usage efficiency, (number of links used by the backup paths) and the computation time for calculating these backup paths. This work is the first to propose metrics for evaluating recovery algorithms for multicasting in WDM optical networks. It is also the first to introduce the concept of hybrid proactive and reactive approach and to propose a simple technique for achieving the proper mix

Coherent multicarrier lightwave technology for flexible capacity networks (invited)

Highly flexible and survivable networks can be built by allocating optical carriers of heterodyne systems. The basic features of heterodyne systems are reviewed, especially the use of multicarriers, tunability, and selectivity. Then specific application areas that may benefit from flexible multicarrier allocation schemes are discussed. Examples are taken from the RACE Phase II project R2065, coherent optical systems implemented for business traffic routing and access (COBRA). Next, trends and progress in heterodyne systems in general and related key components are summarized, and then examples of ongoing field trials in Europe are discussed. Finally, the coherent multicarrier technology are compared briefly with direct detection multiwavelength technolog

Survivable and disaster- resilient submarine optical-fiber cable deployment

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Internete olan mevcut sosyal ve ekonomik bağlılık ve servis kesintileri nedeni ile oluşan önemli miktardaki tamir masrafları ile ağ kalımlılığı günümüzde telekomünikasyon ağ dizaynının önemli bir parçası olmuştur. Ayrıca, denizaltı fiber optik kabloların depremler gibi doğal afetlere veya insan-yapımı afetlere karşı zayıf olduğu da herkesçe kabul edilmiş bir gerçektir. Afete dayanıklı bir denizaltı kablo yerleştirilmesi, bir yada daha fazla kablo afet nedeni ile koptuğunda ağ servislerini yeniden eski haline getirmek için ağ operatörünün maliyetlerini (yolculuk maliyeti, kapasite kayıp maliyeti ve hasar gören kablonun tamir maliyeti) azaltabilir. Bu çalışmada afet-farkındalı denizaltı fiber optik kabloları yerleştirme problemini araştırdık. Kablolar için bir yol/rota seçerken yaklaşımımız toplam beklenen kayıp maliyetini, denizaltı fiber kabloların afetler nedeni ile zarar görebileceğini de düşünerek, bütçe ve diğer kısıtlamalar altında minimize etmeyi hedefler. Yaklaşımımızda afetle ilişkisiz arızaların ana kablonun yanında bir de yedek kablo sağlanarak üstesinden gelindiğini varsaydık. Önce basitçe bir su kütlesi (deniz/okyanus) tarafından ayrılmış iki kara parçası üzerine yerleştirilmiş iki düğümün olduğu bir senaryoyu düşündük. Daha sonra problemi formüle edebilmek için afet bölgelerinden sakınacak şekilde eliptik kablo şeklini dikkate aldık. En nihayetinde problem için, bu durumda yaklaşımımızın potansiyel faydalarını gösteren sayısal örneklerle desteklediğimiz bir Tamsayı Lineer Programlama formülasyonu ürettik. Bununla birlikte problemi daha pratik hale getirmek için, farklı kara parçalarına yerleşmiş çoklu düğümlerin örgüsel bir ağ topolojisini, düzenli şekillere sahip olmayan kabloları, deniz altındaki ortamın topografisini de dikkate aldık. Bu problemi de ifade etmek için sayısal örneklere birlikte bir Tamsayı Lineer Programlama sunduk. Sonuç olarak, pratik durumu düşünerek bir örnek durum incelemesi üzerinde yaklaşımımızı mevcut kablolama sistemleri ile kıyaslayarak teyit ettik. İki durumda da, sonuçlar bize %2-%11 oranında bir yerleştirme maliyeti artışı karşılığında beklenen maliyeti %90-%100 arasında azaltabileceğimizi gösterdi.With the existing profoundly social and economic reliance on the Internet and the significant reparation cost associated with service interruption, network survivability is an important element in telecommunication network design nowadays. Moreover, the fact that submarine optical-fiber cables are susceptible to man-made or natural disasters such as earthquakes is well recognized. A disaster-resilient submarine cable deployment can save cost incurred by network operators such as the capacity-loss cost, the cruising cost and the repair cost of the damaged cables, in order to restore network service when cables break due to a disaster. In this study, we investigate disaster-aware submarine fiber-optic cable deployment problem. While selecting a route/path for cables, our approach aims to minimize the total expected cost, considering that submarine optical-fiber cables may break because of natural disasters, subject to deployment budget and other constraints. In our approach, we assume disaster-unrelated failures are handled by providing a backup cable along with primary cable. In the simple case we consider a scenario with two nodes located on two different lands separated by a water body (sea/ocean). We then consider an elliptic cable shape to formulate the problem, which can be extended to other cable shapes, subject to avoiding deploying cable in disaster zones. Eventuaaly, we provide an Integer Linear Programming formulation for the problem supported with illustrative numerical examples that show the potential benefit of our approach. Furthermore, in order to make the problem more practical, we consider a mesh topology network with multiple nodes located on different sea/ocean, submarine optical- fiber cables of irregular shape, and the topography of undersea environment. Eventually, we provide an Integer Linear Programming to address the problem, together with illustrative numerical examples. Finally, we validate our approach by conducting a case study wherein we consider a practical submarine optical-fiber cable system susceptible to natural disasters. In this case, we compare our approach against the existing cable system in terms of deployment cost and reduction in expected cost. In either case results show that our approach can reduce expected cost from 90% to 100% at a slight increase of 2% to 11% in deployment cost of disaster-unaware approach