An efficient optimization scheme for WDM/TDM PON network planning

With the growing popularity of bandwidth demanding services such as HDTV, VoD, and video conferencing applications, there is an increasing demand on broadband access. To meet this demand, the access networks are evolving from the traditional DSL (xDSL more recently) and cable techniques to a new generation of fiber-based access techniques. While EPONs and GPONs have been the most studied passive optical access networks (PONs), WDM-PON is now clearly seen as the next generation trend with an hybrid set of switching equipment. We propose here an original optimization scheme for the deployment of greenfield PON networks where we minimize the overall deployment cost. Given the geographical location of ONUs and their incoming/outgoing traffic demands, the newly proposed scheme optimizes the placement of splitters/AWGs in a PON and the link dimensioning in order to provision the overall demand. The optimization scheme proceeds in three phases. In the first phase, we generate several potential equipment hierarchies, where each equipment hierarchy is associated with an ONU partition such that a switching equipment is associated with each cluster, each ONU belongs to a single cluster, and the splitting ratio of the equipment corresponds to the number of ONUs in the cluster. In the second phase, for each equipment hierarchy, we make use of a column generation (CG) mathematical model to select the type and location of the switching equipment that leads to the minimum cost multi-stage equipment topology which accommodates all the traffic demand. The third phase selects the best hierarchy among all the generated and dimensioned hierarchies. The optimization model encompasses the particular cases where all switching equipment are either splitters and AWGs, and outputs the location of the switching equipment together with the dimensioning of the PON network. We performed numerical experiments on various data sets in order to evaluate the performance of the optimization model, and to analyze the type of equipment hierarchies which are generated depending on the traffic and the location of the ONUs

Transmission transparency and potential convergence of optical network solutions at the physical layer for bit rates from 2.5 Gb·s-1 to 256 Gb·s-1

In this paper, we investigate optical network recommendations GPON and XG-PON with triple-play services in terms of physical reach, number of subscribers, transceiver design, modulation format and implementation cost. Despite trends to increase the bit rate from 2.5 Gb s1 to 10 Gb s1 and beyond, TDMPONs cannot cope with bandwidth requirements of future networks. TDM and WDM techniques can be combined, resulting in improved scalability. Longer physical reach can be achieved by deploying active network elements within the transmission path. We investigate these options by considering their potential coexistence at the physical layer. Subsequently, we analyse the upgrade of optical channels to 100 Gb s1 and 256 Gb s1 by using advanced modulation formats, which combine polarization division multiplexing with coherent detection and digital signal processing. We show that PDMQPSK format is suitable for 100 Gb s1 systems and PDM-16QAM is more beneficial at 256 Gb s1. Simulations are performed in the OptSim software environment

Switching Equipment Location/Allocation in hybrid PONs

Our research goal is to investigate the FTTX (Fiber-to-the Home/Premises/Curb) passive optical network (PON) for the deployment of BISAN (Broadband Internet Subscriber Access Network) to exploit the opportunities of optical fiber enabled technologies as well as of passive switching equipment. Indeed, the deployment of FTTX PON is the most OPEX-friendly scenario, because it allows for completely passive access networks through minimizing the number of active components in the network. Previously, most FTTX PON architectures are designed based on the principle of either time division multiplexing (TDM) technology or wavelength division multiplexing (WDM) technology. We focus on designing the best possible architectures of FTTX PON, specifically hybrid PONs, which embraces both TDM and WDM technology. A hybrid PON architecture is very efficient as it is not limited to any specific PON technology, rather it is flexible enough to deploy TDM/WDM technology depending on the type (i.e unicast/multicast) and amount of traffic demand of the end-users. The advantages of a hybrid PON are of two folds: (i) it can offer increased data rate to each user by employing WDM technology, (ii) it can provide flexible bandwidth utilization by employing TDM technology. In this thesis, we concentrate on determining the optimized covering of a geographical area by a set of cost-effective hybrid PONs. We also focus on the greenfield deployment of a single hybrid PON. It should be worthy to mention that while investigating the deployment of hybrid PONs, the research community around the world considers the specifications of either the physical layer or the optical layer. But an efficient planning for PON deployment should take into account the constraints of the physical and optical layers in order that both layers can work together harmoniously. We concentrate our research on the network dimensioning and the selection as well as the placement of the switching equipment in hybrid PONs with the intention of considering the constraints of both physical and optical layers. We determine the layout of an optimized PON architecture while provisioning wavelengths in a hybrid PON. We also propose to select the switching equipment depending on the type (unicast/multicast) of traffic demand. Finally, we determine the best set of hybrid PONs along with their cascading architecture, type and location of their switching equipment while satisfying the network design constraints such as the number of output ports of the switching equipment and maximum allowed signal power loss experienced at each end user’s premises. In this thesis, we propose two novel schemes for the greenfield deployment of a single hybrid PON. The first scheme consists of two phases in which a heuristic algorithm and a novel column generation (CG) based integer linear programming (ILP) optimization model are proposed in the 1st and 2nd phase respectively. In the second scheme, a novel integrated CG based ILP cross layer optimization model is proposed for the designing of a single hybrid PON. We also propose two novel schemes to deal with the greenfield deployment of multiple hybrid PONs in a given geographical area. These two schemes determine the best set of cost-effective hybrid PONs in order to serve all the end users in a given neighborhood. The first scheme executes in four phases in which two heuristic algorithms, a CG based ILP model and an ILP optimization model are proposed in the 1st, 2nd, 3rd and 4th phase respectively. In the second scheme, an ILP model as well as a CG based ILP model, another ILP model as well as another CG based ILP model, a CG based ILP model and an ILP optimization model are proposed during four consecutive phases. Our proposed scheme can optimize the design of a set of hybrid PONs covering a given geographic area as well as the selection of the best cascading architecture 1/2/mixedstage) for each selected PON. It minimizes the overall network deployment cost based on the location of the OLT and the ONUs while granting all traffic demands. The scheme emphasizes on the optimum placement of equipment in a hybrid PON infrastructure due to the critical dependency between the network performances and a proper deployment of its equipment, which, in turn depends on the locations of the users. It is a quite powerful scheme as it can handle data instances with up to several thousands ONUs. On the basis of the computational results, the proposed scheme leads to an efficient automated tool for network design, planning, and performance evaluation which can be beneficial for the network designers

Enabling Optical Wired and Wireless Technologies for 5G and Beyond Networks

The emerging fifth-generation mobile communications are envisaged to support massive number of deployment scenarios based on the respective use case requirements. The requirements can be efficiently attended with ultradense small-cell cloud radio access network (C-RAN) approach. However, the C-RAN architecture imposes stringent requirements on the transport networks. This book chapter presents high-capacity and low-latency optical wired and wireless networking solutions that are capable of attending to the network demands. Meanwhile, with optical communication evolutions, there has been advent of enhanced photonic integrated circuits (PICs). The PICs are capable of offering advantages such as low-power consumption, high-mechanical stability, low footprint, small dimension, enhanced functionalities, and ease of complex system architectures. Consequently, we exploit the PICs capabilities in designing and developing the physical layer architecture of the second standard of the next-generation passive optical network (NG-PON2) system. Apart from being capable of alleviating the associated losses of the transceiver, the proposed architectures aid in increasing the system power budget. Moreover, its implementation can significantly help in reducing the optical-electrical-optical conversions issue and the required number of optical connections, which are part of the main problems being faced in the miniaturization of network elements. Additionally, we present simulation results for the model validation

Optimization of multiple PON deployment costs and comparison between GPON, XGPON, NGPON2 and UDWDM PON

In this paper we propose an optimization framework for multiple deployment of PON in a wide region with very large number of users, with different bit rate demands, serviced by many central offices, as it may practically happen in a large city that plans a massive introduction of Fiber to the Home technologies using PON. We propose an algorithm called Optimal Topology Search (OTS), which is based on a set of heuristic approaches, capable of performing an optimal dimensioning of multiple PON deployments for a set of central offices (CO), including an optimal distribution of users among the CO. The set of heuristics integrated in OTS permit the efficient clustering of users for each CO, depending on their location and the bit rate demanded by them. It also permits the definition of optimal routes for optical cables and the allocation of branching devices. Taking into account hardware capacity restrictions and physical layer restrictions, we obtained solutions for different types of standardized PON technologies, like GPON, XGPON and NGPON2 as well as for future UDWDM-PON. We evaluate the optimal network deployment in a series of different minimum guaranteed bit rate demand scenarios, employing realistic maps of a large city in order to compare costs and portrait some reference points for deciding in which scenario a specific technology constitutes the best choice

Access and metro network convergence for flexible end-to-end network design

This paper reports on the architectural, protocol, physical layer, and integrated testbed demonstrations carried out by the DISCUS FP7 consortium in the area of access - metro network convergence. Our architecture modeling results show the vast potential for cost and power savings that node consolidation can bring. The architecture, however, also recognizes the limits of long-reach transmission for low-latency 5G services and proposes ways to address such shortcomings in future projects. The testbed results, which have been conducted end-to-end, across access - metro and core, and have targeted all the layers of the network from the application down to the physical layer, show the practical feasibility of the concepts proposed in the project

Location Models for Two Different Applications

There has been a growing interest in location problems for their wide use in many areas, such as passive optical networks and logistics networks. However, as the papers appear in different literature, researchers usually do not take advantage of their mutual findings. We propose to bridge the gaps and therefore to propose efficient solutions schemes for two different applications. In the first application, our research goal is to investigate the FTTX (Fiber-to-the Home/Premises/Curb) passive optical network (PON) for the deployment of broadband access. We focus on designing the best possible architectures of FTTX hybrid PONs, which embraces both Time Division Multiplexing (TDM) and Wave Division Multiplexing (WDM) technology. A hybrid PON architecture is very efficient as it is not limited to any specific PON technology, rather it is flexible enough to deploy TDM/WDM technology depending on the type (i.e., unicast/multicast) and amount of traffic demand of the end-users. We investigate the optimized covering of a geographical area by a set of cost-effective hybrid PONs. We propose a novel network design optimization scheme for greenfield deployment of a set of hybrid PONs, in which all significant constraints are taken into account, e.g., type of traffic, attenuation, choice of splitting equipment. In the second application, we revisit the p-center location problem in the context of disruption events. We propose an optimized covering in the geographical area for a given number of customers and suppliers, ensuring each customer is assigned a primary supplier and a different backup supplier unless the primary supplier has a so-called fortified facility. However, the budget for facility fortification is limited and only few facilities can be fortified. We design an optimization model under the assumption of single event disruptions, and estimate accurately the required facility capacities while taking into account a sharing of the backup resources. We evaluate our proposed models and algorithms by a comprehensive set of numerical experiments, with some comparisons in each of these two applications. Conclusions are drawn in the last chapter