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Reliability versus Cost in Next Generation Optical Access Networks
KTH, School of Information and Communication Technology (ICT), Communication Systems, CoS, Optical Network Laboratory (ON Lab).ORCID iD: 0000-0003-2004-3350
2013 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

The ever increasing demands of Internet users caused by the introduction of new high bandwidth applications and online services as well as the growing number of users and devices connected to the Internet, bring many challenges for the operators, especially in the last mile section of the network. Next generation access architectures are expected to offer high sustainable bandwidth per user. They also need to support a much larger service areas to decrease number of current central offices and hence potentially save the network expenditures in the future. Obviously, it requires high capacity and low loss transmission and optical fiber technology is the only future proof candidates for broadband access. Although this technology has already been widely deployed in the core networks, it is hard to use the same expensive devices made for core segment to solve the last mile bottlenecks, due to the low number of users sharing the network resources (and deployment cost). Therefore, the next generation optical access (NGOA) networks need to be designed with consideration of cost efficiency in the first place.

 

Network reliability is also turning to be an important aspect for the NGOA networks as a consequence of long reach, high client count and new services requiring uninterrupted access. Consequently, new architectures not only need to be cost efficient but also they should fulfill the increasing reliability requirements.

 

Although several NGOA alternatives have been proposed in the literatures, there is not yet an agreement on a single architecture. As described earlier, network expenditure and reliability performance are the two main factors to be considered. Therefore, this thesis concentrates on finding a suitable alternative for future broadband access by evaluating the reliability performance and total cost of ownership for several NGOA candidates. In particular, in this thesis we analyze the tradeoff between the cost needed to deploy backup resources and the reliability performance improvement obtained by the provided survivability mechanism.

 

First, we identified the suitable NGOA candidates by comparing two main groups of optical access networks, namely passive optical networks (PONs) and active optical networks (AONs), in terms of cost, reliability performance and power consumption. The initial results have shown that wavelength division multiplexing PON (WDM PON) is the most promising alternative for the NGOA networks because of its high potential capacity, low cost and power consumption. So we continued our studies by investigating two WDM-based PON architectures regarding their cost and reliability performance. The study has also included a proposed fiber layout compatible with these two candidates aiming to minimize the required investment needed to offer protection. Our primary results confirmed that hybrid PON (HPON) is the best alternative for the NGOA networks. Therefore we further analyzed this candidate considering several variants of HPON. The most important components and sections of the HPON, which need to be protected to decrease the impact of each failure in the network have been identified. Based on these outcomes, two resilience architectures protecting the shared part of the HPON were proposed and their reliability performance parameters as well as cost of protection were evaluated. According to the results, using our proposed protection schemes a considerable improvement in reliability performance of the HPON variants can be provided at minor extra investment. We also introduced a cost efficient HPON architecture with different levels of protection for users with various reliability requirements, i.e. the protection of shared parts of the access network for all the connected users and end-to-end resilience scheme for some selected ones (e.g., business users). To gain an overall view on the cost efficiency of the proposed architecture, we evaluated the investment required for deploying these schemes considering several network upgrading paths towards a protected network. Moreover, a sensitivity analysis investigating the influence of network deployments time and the density of the users with higher availability requirements was presented.

 

In summary, we have shown that HPON is able to fulfill the main NGOA requirements such as high bandwidth per-user, large coverage and client count. The work carried out in the thesis has proved that HPON can also offer high reliability performance while keeping the network expenditures at an acceptable level. Moreover, low power consumption and high flexibility in resource allocation of this architecture, makes it a winning candidate for the NGOA networks. Therefore, HPON is a promising architecture to be deployed as NGOA network in the near future considering the fact that components are soon to be available in the market.

Place, publisher, year, edition, pages
Stockholm: KTH Royal Institute of Technology, 2013. , xiv, 46 p.
Series
Trita-ICT-COS, ISSN 1653-6347 ; 1303
Keyword [en]
Fiber access network, passive optical network, reliability, techno-economic study, next generation optical access, network protection, wavelength division multiplexing
National Category
Communication Systems
Identifiers
URN: urn:nbn:se:kth:diva-122380ISBN: 978-91-7501-749-5 (print)OAI: oai:DiVA.org:kth-122380DiVA: diva2:622071
Presentation
2013-06-12, Sal D, Forum, Isafjordsgatan 39, Kista, 10:00 (English)
Opponent
Supervisors
Projects
FP7 EU project, Optical Access Seamless Evolution(OASE)
Note

QC 20130530

Available from: 2013-05-30 Created: 2013-05-20 Last updated: 2013-05-30Bibliographically approved
List of papers
1. Fiber access networks: Reliability and power consumption analysis
Open this publication in new window or tab >>Fiber access networks: Reliability and power consumption analysis
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2011 (English)In: ONDM 2011 - 15th Conference on Optical Network Design and Modeling, Bologna, 2011, 5753402- p.Conference paper, Published paper (Refereed)
Abstract [en]

Optical access networks are being widely deployed due to their high capacity and scalability. The reliability of these networks is a key issue because of the impact of failures on both the number of interrupted services and significance of the service interruptions for the community. Consequently, the service interruption penalties that a network operator would need to pay are directly related to the network reliability performance. Nowadays, penalties are paid to business customers when the service interruption time is longer than the value of the Service Level Agreement agreed with the operator. However, the number of users requesting penalties increases, which has triggered the need of protection mechanisms in access networks. In this paper, the investments required to offer protection for different planning approaches will be compared for different optical access technologies (TDM, WDM, AON and P2P). The evaluation of the costs associated to each scenario such as infrastructure, equipment, power consumption, failure reparation etc. is presented. The overall cost reduction when investing on infrastructure protection is highlighted.

Place, publisher, year, edition, pages
Bologna: , 2011
Series
15th Conference on Optical Network Design and Modeling, ONDM 2011
Keyword
Access network, Business customers, High capacity, Infrastructure protection, Network operator, Network reliability, Optical access networks, Optical access technology, Power Consumption, Power consumption analysis, Protection mechanisms, Service interruption, Service Level Agreements, Cost reduction, Fiber optic networks, Investments, Reliability analysis
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-52661 (URN)2-s2.0-79956145661 (Scopus ID)9783901882425 (ISBN)
Conference
15th Conference on Optical Network Design and Modeling, ONDM 2011; Bologna; 8 February 2011 through 10 February 2011
Funder
ICT - The Next Generation
Note
QC 20111219Available from: 2011-12-19 Created: 2011-12-19 Last updated: 2013-05-30Bibliographically approved
2. Protection cost evaluation of two WDM-based next generation optical access networks
Open this publication in new window or tab >>Protection cost evaluation of two WDM-based next generation optical access networks
2011 (English)In: Proceedings of SPIE: The International Society for Optical Engineering, 2011, 83100P- p.Conference paper, Published paper (Other academic)
Abstract [en]

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.

Series
Proceedings of SPIE, ISSN 0277-786X ; Vol. 8310
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-59558 (URN)10.1117/12.902462 (DOI)000298881200015 ()2-s2.0-84862917537 (Scopus ID)
Conference
Network Architectures, Management, and Applications IX; Shanghai, China, 13-16 November, 2011
Funder
ICT - The Next Generation
Note

QC 20120124

Available from: 2012-01-11 Created: 2012-01-11 Last updated: 2015-03-20Bibliographically approved
3. Protection cost evaluation of WDM-based next generation optical access networks
Open this publication in new window or tab >>Protection cost evaluation of WDM-based next generation optical access networks
2013 (English)In: Optical Switching and Networkning Journal, ISSN 1573-4277, E-ISSN 1872-9770, Vol. 10, no 1, 89-99 p.Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Next generation optical access networks, Wavelength division multiplexing, Passive optical networks
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-110053 (URN)10.1016/j.osn.2012.07.002 (DOI)000312181700009 ()2-s2.0-84869086685 (Scopus ID)
Funder
EU, FP7, Seventh Framework Programme, 249025
Note

QC 20130110

Available from: 2013-01-10 Created: 2013-01-10 Last updated: 2017-12-06Bibliographically approved
4. Efficient protection schemes for hybrid WDM/TDM Passive Optical Networks
Open this publication in new window or tab >>Efficient protection schemes for hybrid WDM/TDM Passive Optical Networks
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2012 (English)In: Communications (ICC), 2012 IEEE International Conference on, IEEE , 2012, 6220-6224 p.Conference paper, Published paper (Refereed)
Abstract [en]

Hybrid WDM/TDM Passive Optical Network (PON) is a promising candidate for next-generation optical access (NGOA) solutions as it is able to offer a high splitting ratio and consequently achieves a relatively low cost and power consumption on a per-user basis compared with other NGOA architectures. On the other hand, the end users require a certain level of connection availability while the operators need to reduce the failure impact (i.e. to avoid a huge number of end users being affected by any single failure). Therefore, by evaluating the connection availability and failure impact robustness we identify the most efficient parts to provide resilience in a hybrid WDM/TDM PON from an operator and an end-user perspective. Then, we select the appropriate protection schemes to construct some novel reliable architectures and analyze their reliability performance in urban and rural scenarios. In this way, this paper provides a comprehensive insight into the most relevant protection mechanisms for hybrid WDM/TDM PONs.

Place, publisher, year, edition, pages
IEEE, 2012
Series
IEEE International Conference on Communications, ISSN 1550-3607
Keyword
Availability, Failure Impact Robustness, Hybrid WDM/TDM PON, Resilience
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-115472 (URN)10.1109/ICC.2012.6364787 (DOI)2-s2.0-84871955804 (Scopus ID)978-145772052-9 (ISBN)
Conference
2012 IEEE International Conference on Communications, ICC 2012, 10 June 2012 through 15 June 2012, Ottawa, ON
Note

QC 20130116

Available from: 2013-01-16 Created: 2013-01-15 Last updated: 2015-03-20Bibliographically approved
5. Towards Reliable Hybrid WDM/TDM Passive Optical Networks
Open this publication in new window or tab >>Towards Reliable Hybrid WDM/TDM Passive Optical Networks
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(English)Manuscript (preprint) (Other academic)
National Category
Communication Systems
Identifiers
urn:nbn:se:kth:diva-122379 (URN)
Note

QS 2013

Available from: 2013-05-20 Created: 2013-05-20 Last updated: 2013-05-30Bibliographically approved

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Mahloo, Mozhgan

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