Toward reliable hybrid WDM/TDM passive optical networks

Abstract

Individual users and enterprises are increasingly relying on the access to internet services and cannot accept long interruption time as easily as before. Moreover, the main characteristics of next generation optical access (NGOA) networks, such as long reach and large number of users per feeder line, turn the network reliability to an important design parameter to offer uninterrupted service delivery. In this regard, protection mechanisms become one of the crucial aspects that need to be considered in the design process of access networks. On the other hand, it should be noted that not all the users can afford to pay a high extra cost for protection and hence it is important to provide resilience in a costefficient way.A passive optical network (PON) combining wavelength division multiplexing (WDM) and time division multiplexing (TDM) technologies, referred to as hybrid WDM/TDM PON or HPON, is one of the most promising candidates for NGOA networks due to its ability to serve a large number of subscribers and to offer a high capacity per user. For these reasons in this paper, we propose HPON architecture offering different degrees of resilience depending on the user profiles, i.e. partial and full protection for residential and business access, respectively. Besides, the investment cost of providing resilience for the proposed schemes is investigated considering various protection upgrade road maps.Our results confirm that protecting the shared part of network with a large number of users is required in order to keep the failure impact at an acceptable level, with less than 5% increase of the investment cost compared to the unprotected case. Meanwhile, the proposed end-to-end protection for the business users considerably reduces the risk of service interruption for this kind of demanding users without a need for duplicating the deployment cost of an unprotected connection. Furthermore, a sensitivity analysis is performed to investigate the impact of changes in business user percentage and protection upgrade time on the deployment cost. The results may be used as an advice for a costefficient deployment of reliable fiber access networks.

Dimensioning and Assessment of Protected Converged Optical Access Networks

“…Several architectures have been proposed in literature: NGPON2 [1], WDM-PON [1], HPON [1], [10]. Most of these architectures have more than one splitting stage.…”

“… Indirect improvement in connection availability of residential users: Although the objective of these protection schemes is to increase the connection availability between MCO-MBS, some schemes also increase the connection availability between MCO-Residential users.  Failure Impact Factor (FIF) is defined as the number of affected users/connections when a particular failure occurs [10]. The FIF of an unprotected component is computed as the product of its unavailability and its FPR.…”

Reliable and Cost Efficient Passive Optical Interconnects for Data Centers

“…The overall results cover the cases of 1 Gbps and 10 Gbps transmission capacity per server. Table I shows the MTBF and the cost values for the involved components [8], [13], [14], which are used to evaluate the reliability and the total cost of the proposed POI architectures. Fig.…”

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

“…However, the conventional PON architecture has limited protection, which results in significant data loss at the event of failure in optical components including OF medium. Therefore, it is imperative to devise an architecture, which is capable of maintaining a seamless flow of upstream and downstream traffic at required capacity and acceptable costs for a common end subscriber [1,2].…”

“…Such technique requires more time for traffic restoration between OLT and ONU modules, as upper layer recovery techniques usually utilize routing tables, topology recalculations, and slow convergence time. Yet there is no guarantee for fault restoration at the physical layer [1][2][3]. Therefore, for the facilitation of an effective and prompt fault detection and restoration, it is highly desirable to provide protection measures at the optical layer.…”