| 1. |
- de Sousa, Amaro, et al.
(författare)
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Structural Methods to Improve the Robustness of Anycast Communications to Large-Scale Failures
- 2020
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Ingår i: Guide to Disaster-Resilient Communication Networks. - Cham : Springer International Publishing. - 9783030446857 ; , s. 401-425
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Bokkapitel (övrigt vetenskapligt/konstnärligt)abstract
- This chapter is dedicated to the description of structural methods aiming to improve the robustness of anycast communications to large-scale failures, either due to natural disasters or malicious human activities. The chapter considers both software-defined networks (SDNs) where the anycast nodes are the nodes hosting SDN controllers, and content delivery networks (CDNs) where the anycast nodes are the nodes hosting content replicas. Most of the structural methods described in this chapter aim to optimally select the anycast nodes in a given network. The chapter first addresses the robustness of anycast communications to natural disasters based on geodiversity routing. Then, different methods are described to select the SDN controller locations aiming to maximize the SDN control plane robustness to malicious node attacks. Finally, the chapter addresses the robustness of CDNs to malicious link cuts by describing methods for the network upgrade (based either on the addition of new links or new replica locations) and for the optimal selection of content replica locations.
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| 2. |
- Furdek Prekratic, Marija, 1985, et al.
(författare)
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Introduction to the ONDM 2021 special issue
- 2022
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 14:5, s. ONDM1-ONDM2
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- This JOCN special issue contains extended versions of selected papers presented at the 25th International Conference on Optical Network Design and Modeling (ONDM 2021), which took place virtually from 28 June through 1 July 2021. The topics covered by the papers represent clear trends in current optical networking research, including capacity upgrade through transmission parameter optimization in multiband systems, spectral efficiency improvement through probabilistic constellation shaping in Flex Grid/multicore fiber networks, novel point-to-multipoint optical architectures based on digital subcarrier multiplexing that enable a rethink of multilayer network design, and trustworthy inter-operator sharing of passive optical network capacity based on a smart contract.
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| 3. |
- Grigoreva, Elena, et al.
(författare)
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Energy Consumption and Reliability Performance of Survivable Passive Optical Converged Networks: Public ITS Case Study
- 2017
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Ingår i: Journal of Optical Communications and Networking. - : Optical Society of America. - 1943-0620 .- 1943-0639. ; 9:4, s. C98-C107
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Tidskriftsartikel (refereegranskat)abstract
- Access networks are evolving fast by increasing their capacity and coverage area, coping with a larger number of users and variety of terminals. Operators aim at keeping high network performance and quality of service but limiting their capital and operational expenditures by, e.g., minimizing investments and energy consumption using power saving at the network components. To address these challenges this paper evaluates the energy consumption, connection availability, and failure detection time of three protection schemes applicable for converged access networks: disjoint fiber protection, energy-efficient disjoint fiber protection, and reflective disjoint fiber protection. The schemes are assessed by a case study considering a public intelligent transport system (ITS). The studied ITS deploys a dedicated short-range communications radio access network connected to the service server through a protected passive access network. Comparison with unprotected architecture shows that reflective disjoint fiber protection offers low energy consumption and high connection availability, while it significantly reduces the failure detection time and, hence, the connection interruption time.
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| 4. |
- Machuca, Carmen Mas, et al.
(författare)
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Cost dependency on protection of optical access networks for dense urban areas
- 2011
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Ingår i: International Conference on Transparent Optical Networks. - Stockholm. - 9781457708800
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Konferensbidrag (refereegranskat)abstract
- Along with the competition on the telecom market and high reliability requirements of the emerging services operators and service providers are forced to increase connection availability of all users supported by their network. For economical reason most of the investment related to providing protection resources has been so far limited to the core and metro networks. On the other hand, increasing requirement for interrupted access to the network services is moving the focus for protection towards the end user. However, the cost to offer protection in access networks is a limiting factor. In this paper, a protection scenario for passive optical network in dense urban area is proposed. The cost of this protection approach is analysed, and furthermore, the key cost drivers are identified. It is shown that the failure rates of fiber and Optical Network Units (ONUs) and basic salary of technicians are the main cost drivers for the considered dense urban area.
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| 5. |
- Mahloo, Mozhgan, 1983-, et al.
(författare)
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Protection cost evaluation of two WDM-based next generation optical access networks
- 2011
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Ingår i: 2011 Asia Communications and Photonics Conference and Exhibition. - Washington, D.C. : Optical Society of America (OSA). - 9780819489616 ; , s. 83100P-
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Konferensbidrag (refereegranskat)abstract
- In this paper, we investigate the capital and operational expenditures for two next generation optical access (NGOA) networks based on wavelength division multiplexing (WDM) technology in dense urban areas. It is shown that with a proper fiber layout design, minor extra investment for protection of NGOA networks can make a significant saving on failure related operational cost.
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| 6. |
- Mahloo, Mozhgan, et al.
(författare)
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Protection cost evaluation of WDM-based next generation optical access networks
- 2013
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Ingår i: Optical Switching and Networkning Journal. - : Elsevier BV. - 1573-4277 .- 1872-9770. ; 10:1, s. 89-99
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Tidskriftsartikel (refereegranskat)abstract
- New technologies and advanced network devices make it possible to move towards high capacity access networks able to satisfy the growing traffic demand. Wavelength division multiplexing (WDM) is considered as one of the promising technologies for the next generation access networks since it offers higher bandwidth and longer reach compared to the current technologies (such as time division multiplexing (TDM) based networks). However, the migration to a new technology is typically based on an overall techno-economic study which should assure the network operator that the new implementation is cost effective and profitable while able to provide the required services to the users. Another important aspect in the access network design is the network reliability performance, which can be improved by providing a certain level of protection for equipment and/or infrastructure with high failure impact ratio in order to prevent a big number of the users being affected by a single failure. The cost of protection should be carefully evaluated since providing the backup resources may be too expensive for a network operator. In this paper, we investigate the capital and operational expenditures for two next generation optical access (NGOA) networks based on the WDM technology in dense urban areas. Three scenarios with different splitting ratios are studied for each technology, with and without protection. The aim of this work is to investigate the impact of providing protection on the total cost of NGOA networks. The results show that in the dense urban areas the fibers and digging costs are highly shared among the end users but still vary according to the splitting ratios for different scenarios and the fiber layout. It also can be seen that with a proper fiber layout design, minor extra investment for protection of NGOA networks can make a significant saving on failure related operational cost and that operational expenditures depend significantly on the fiber layout.
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| 7. |
- Mahloo, Mozhgan, et al.
(författare)
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Toward Reliable Hybrid WDM/TDM Passive Optical Networks
- 2014
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Ingår i: IEEE Communications Magazine. - 0163-6804 .- 1558-1896. ; 52:2, s. S14-S23
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Tidskriftsartikel (refereegranskat)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 a 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 users can afford to pay a high extra cost for protection; hence, it is important to provide resilience in a cost-efficient way. A PON combining WDM and 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 offer high capacity per user. For these reasons, in this article, 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). Also, 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 percent increase of investment cost compared to the unprotected case. Meanwhile, the proposed end-to-end protection for business users considerably reduces the risk of service interruption for this type of demanding user without a need to duplicate 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 advice on cost-efficient deployment of reliable fiber access networks.
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| 8. |
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| 9. |
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| 10. |
- Mas-Machuca, Carmen, et al.
(författare)
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Methodology for a cost evaluation of migration toward NGOA networks
- 2013
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Ingår i: Journal of Optical Communications and Networking. - 1943-0620 .- 1943-0639. ; 5:12, s. 1456-1466
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Tidskriftsartikel (refereegranskat)abstract
- Evolution of optical access networks promises to bring higher bandwidth to more customers. However, this evolution toward so-called next generation optical access (NGOA) networks also introduces additional challenges that operators and/or vendors have to address: how to properly estimate and compare different NGOA architectures and their evolutionary paths in terms of their economics. Calculating the total cost of ownership (TCO) for NGOA networks is a very complex target as it needs to involve good knowledge of the technology, the existing network infrastructure, and any migration-related processes. In this paper a complete methodology is presented for evaluating the TCO of the migration toward a NGOA network. It contains a detailed description of which key aspects have to be considered, which processes they affect, and how they are translated into costs in a logical manner. Finally, it also shows how this methodology has been applied to particular selected cases and how it gives a detailed view of all costs involved in migration. This approach opens up opportunities to cooperate in techno-economic research using it as a base. Both operators and vendors can also utilize this approach to get a useful economic background of their future investments and potential sales.
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