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Muhammad, Ajmal
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Publications (10 of 16) Show all publications
Muhammad, A. (2015). Planning and Provisioning Strategies for Optical Core Networks. (Doctoral dissertation). Linköping: Linköping University Electronic Press
Open this publication in new window or tab >>Planning and Provisioning Strategies for Optical Core Networks
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Optical communication networks are considered the main catalyst for the transformation of communication technology, and serve as the backbone of today's Internet. The inclusion of exciting technologies, such as, optical amplifiers, wavelength division multiplexing (WDM), and reconfigurable optical add/drop multiplexers (ROADM) in optical networks have made the cost of information transmission around the world negligible. However, to maintain the cost effectiveness for the growing bandwidth demand, facilitate faster provisioning, and provide richer sets of service functionality, optical networks must continue to evolve. With the proliferation of cloud computing the demand for a promptly responsive network has increased. Moreover, there are several applications, such as, real time multimedia services that can become realizable, depending on the achievable connection set-up time.

Given the high bandwidth requirements and strict service level specifications (SLSs) of such applications, dynamic on-demand WDM networks are advocated as a first step in this evolution. SLSs are metrics of a service level agreement (SLA), which is a contract between a customer and network operator. Apart from the other candidate parameters, the set-up delay tolerance, and connection holding-time have been defined as metrics of SLA. Exploiting these SLA parameters for on-line provisioning strategies exhibits a good potential in improving the overall network blocking performance. However, in a scenario where connection requests are grouped in different service classes, the provisioning success rate might be unbalanced towards those connection requests with less stringent requirements, i.e., not all the connection requests are treated in a fair way.

The first part of this thesis focuses on different scheduling strategies for promoting the requests belonging to smaller set-up delay tolerance service classes. The first part also addresses the problem of how to guarantee the signal quality and the fair provisioning of different service classes, where each class corresponds to a specified target of quality of transmission. Furthermore, for delay impatient applications the thesis proposes a provisioning approach, which employs the possibility to tolerate a slight degradation in quality of transmission during a small fraction of the holding-time.

The next essential phase for scaling system capacity and satisfying the diverse customer demands is the introduction of flexibility in the underlying technology. In this context, the new optical transport networks, namely elastic optical networks (EON) are considered as a worthwhile solution to efficiently utilize the available spectrum resources. Similarly, space division multiplexing (SDM) is envisaged as a promising technology for the capacity expansion of future networks. Among the alternative for flexible nodes, the architecture on demand (AoD) node has the capability to dynamically adapt its composition according to the switching and processing needs of the network traffic.

The second part of this thesis investigates the benefits of set-up delay tolerance for EON by proposing an optimization model for dynamic and concurrent connection provisioning. Furthermore, it also examines the planning aspect for flexible networks by presenting strategies that employ the adaptability inherent in AoD. Significant reduction in switching devices is attainable by proper planning schemes that synthesized the network by allocating switching device where and when needed while maximizing fiber switching operation. In addition, such a design approach also reduces the power consumption of the network. However, cost-efficient techniques in dynamic networks can deteriorate the network blocking probability owing to insufficient number of switching modules. For dynamic networks, the thesis proposes an effective synthesis provisioning scheme along with a technique for optimal placement of switching devices in the network nodes.

The network planning problem is further extended to multi-core-fiber (MCF) based SDM networks. The proposed strategies for SDM networks aim to establish the connections through proper allocation of spectrum and core while efficiently utilizing the spectrum resources. Finally, the optimal planning strategy for SDM networks is tailored to fit synthetic AoD based networks with the goal to optimally build each node and synthesize the whole network with minimum possible switching resources.

Place, publisher, year, edition, pages
Linköping: Linköping University Electronic Press, 2015. p. 84
Series
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1645
National Category
Information Systems Computer and Information Sciences
Identifiers
urn:nbn:se:liu:diva-115908 (URN)10.3384/diss.diva-115908 (DOI)978-91-7519-115-7 (ISBN)
Public defence
2015-04-30, Signalen, Hus B, Campus Valla, Linköping, 10:15 (English)
Opponent
Supervisors
Available from: 2015-03-23 Created: 2015-03-23 Last updated: 2018-01-11Bibliographically approved
Muhammad, M., Zervas, G. & Forchheimer, R. (2015). Resource Allocation for Space-Division Multiplexing: Optical White Box Versus Optical Black Box Networking. Journal of Lightwave Technology, 33(23), 4928-4941
Open this publication in new window or tab >>Resource Allocation for Space-Division Multiplexing: Optical White Box Versus Optical Black Box Networking
2015 (English)In: Journal of Lightwave Technology, ISSN 0733-8724, E-ISSN 1558-2213, Vol. 33, no 23, p. 4928-4941Article in journal (Refereed) Published
Abstract [en]

Elastic optical networking (EON) with space-division multiplexing (SDM) is the only evident long-term solution to the capacity needs of the future networks. The introduction of space via spatial fibers, such as multicore fibers (MCF) to EON provides an additional dimension as well as challenges to the network planning and resource optimization problem. There are various types of technologies for SDM transmission medium, switching, and amplification; each of them induces different capabilities and constraints on the network. For example, employing MCF as the transmission medium for SDM mitigates the spectrum continuity constraint of the routing and spectrum allocation problem for EON. In fact, cores can be switched freely on different links during routing of the network traffic. On the other hand, intercore crosstalk should be taken into account while solving the resource allocation problem. In the framework of switching for elastic SDM network, the programmable architecture on demand (AoD) node (optical white box) can provide a more scalable solution with respect to the hard-wired reconfigurable optical add/drop multiplexers (ROADMs) (optical black box). This study looks into the routing, modulation, spectrum, and core allocation (RMSCA) problem for weakly-coupled MCF-based elastic SDM networks implemented through AoDs and static ROADMs. The proposed RMSCA strategies integrate the spectrum resource allocation, switching resource deployment, and physical layer impairment in terms of intercore crosstalk through a multiobjective cost function. The presented strategies perform a cross-layer optimization between the network and physical layers to compute the actual intercore crosstalk for the candidate resource solutions and are specifically tailored to fit the type of optical node deployed in the network. The aim of all these strategies is to jointly optimize the switching and spectrum resource efficiency when provisioning demands with diverse capacity requirements. Extensive simulation results demonstrate that 1) by exploiting the dense intranodal connectivity of the ROADM-based SDM network, resource efficiency and provisioned traffic volume improve significantly related to the AoD-based solution, 2) the intercore crosstalk aware strategies improve substantially the provisioned traffic volume for the AoD-based SDM network, and 3) the switching modules grows very gently for the network designed with AoD nodes related to the one with ROADMs as the traffic increases, qualifying AoD as a scalable and cost-efficient choice for future SDM networks.

Place, publisher, year, edition, pages
IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2015
Keywords
Architecture on demand; inter-core crosstalk; multi-core fiber; network planning; quasi-static traffic; space division multiplexing
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-123515 (URN)10.1109/JLT.2015.2493123 (DOI)000365228100001 ()
Note

Funding Agencies|Swedish Research Council [2014-6230]; EPSRC [EP/L027070/1 SONATAS]

Available from: 2015-12-22 Created: 2015-12-21 Last updated: 2017-12-01
Ajmal, M., Furdek, M., Monti, P., Wosinska, L. & Forchheimer, R. (2014). An Optimization Model for Dynamic Bulk Provisioning in Elastic Optical Networks. In: Asia Communications and Photonics Conference 2014: . Paper presented at Asia Communications and Photonics Conference, November 11-14, Shanghai, China (pp. AF3E.6). Optics Info Base, Optical Society of America
Open this publication in new window or tab >>An Optimization Model for Dynamic Bulk Provisioning in Elastic Optical Networks
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2014 (English)In: Asia Communications and Photonics Conference 2014, Optics Info Base, Optical Society of America, 2014, p. AF3E.6-Conference paper, Published paper (Refereed)
Abstract [en]

We investigate benefits of setup-delay tolerance in elastic optical networks and propose an optimization model for dynamic and concurrent connection provisioning. Simulation shows that the proposed strategy offers significant improvement of the network blocking performance.

Place, publisher, year, edition, pages
Optics Info Base, Optical Society of America, 2014
Keywords
Fiber optics and optical communications; Networks, network optimization
National Category
Information Systems Computer Sciences
Identifiers
urn:nbn:se:liu:diva-115904 (URN)10.1364/ACPC.2014.AF3E.6 (DOI)2-s2.0-84918576254 (Scopus ID)978-1-55752-852-0 (ISBN)
Conference
Asia Communications and Photonics Conference, November 11-14, Shanghai, China
Available from: 2015-03-23 Created: 2015-03-23 Last updated: 2018-01-11Bibliographically approved
Muhammad, A., Zervas, G. S., Amaya, N., Simeonidou, D. & Forchheimer, R. (2014). Cost-Efficient Design of Flexible Optical Networks Implemented by Architecture on Demand. In: 2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC): San Francisco, California United States 9–13 March 2014. Paper presented at Optical Fiber Communications Conference and Exhibition (OFC) (pp. W2A.17). IEEE
Open this publication in new window or tab >>Cost-Efficient Design of Flexible Optical Networks Implemented by Architecture on Demand
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2014 (English)In: 2014 OPTICAL FIBER COMMUNICATIONS CONFERENCE AND EXHIBITION (OFC): San Francisco, California United States 9–13 March 2014, IEEE , 2014, p. W2A.17-Conference paper, Published paper (Refereed)
Abstract [en]

Architecture on demand (AoD) node offers considerable flexibility against traditional ROADMs. The paper presents a cost-efficient network planning strategy that exploits the flexibility inherent in AoD. Results show that AoD can save significantly in node modules through a proper network design.

Place, publisher, year, edition, pages
IEEE, 2014
National Category
Communication Systems
Identifiers
urn:nbn:se:liu:diva-122087 (URN)10.1364/OFC.2014.W2A.17 (DOI)000361020300538 ()978-1-55752-993-0 (ISBN)
Conference
Optical Fiber Communications Conference and Exhibition (OFC)
Available from: 2015-10-19 Created: 2015-10-19 Last updated: 2015-10-27
Ajma, M., Furdek, M., Monti, P., Wosinska, L. & Forchheimer, R. (2014). Dynamic provisioning utilizing redundant modules in elastic optical networks based on architecture on demand nodes. In: European Conference on Optical Communication (ECOC), 2014: . Paper presented at European Conference on Optical Communication (ECOC), 2014, September 21-25, Cannes, France (pp. 1-3). IEEE
Open this publication in new window or tab >>Dynamic provisioning utilizing redundant modules in elastic optical networks based on architecture on demand nodes
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2014 (English)In: European Conference on Optical Communication (ECOC), 2014, IEEE , 2014, p. 1-3Conference paper, Published paper (Refereed)
Abstract [en]

Survivable synthetic ROADMs are equipped with redundant switching modules to support failure recovery. The paper proposes a dynamic connection provisioning strategy which exploits these idle redundant modules to provision regular traffic resulting in a substantial improvement in the blocking performance.

Place, publisher, year, edition, pages
IEEE, 2014
Keywords
optical fibre networks; telecommunication traffic; demand nodes; dynamic connection provisioning strategy; dynamic provisioning; elastic optical networks; failure recovery; redundant switching modules; survivable synthetic ROADM; Availability; Educational institutions; Optical add-drop multiplexers; Optical fiber networks; Optical switches; Ports (Computers)
National Category
Information Systems Computer Sciences
Identifiers
urn:nbn:se:liu:diva-115906 (URN)10.1109/ECOC.2014.6963998 (DOI)2-s2.0-84915818579 (Scopus ID)
Conference
European Conference on Optical Communication (ECOC), 2014, September 21-25, Cannes, France
Available from: 2015-03-23 Created: 2015-03-23 Last updated: 2018-01-11Bibliographically approved
Ajmal, M., Zervas, G., Saridis, G., Salas, E. H., Simeonidou, D. & Forchheimer, R. (2014). Flexible and Synthetic SDM Networks with Multi-core-Fibers Implemented by Programmable ROADMs. In: Proceedings of European Conference on Optical Communication ECOC2014, Cannes, France, September 21-25 September 2014: . Paper presented at European Conference on Optical Communication ECOC2014, Cannes, France, September 2014 (pp. 1-3). IEEE
Open this publication in new window or tab >>Flexible and Synthetic SDM Networks with Multi-core-Fibers Implemented by Programmable ROADMs
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2014 (English)In: Proceedings of European Conference on Optical Communication ECOC2014, Cannes, France, September 21-25 September 2014, IEEE , 2014, p. 1-3Conference paper, Published paper (Refereed)
Abstract [en]

This study looks into network planning issues for synthetic MCF-based SDM networks implemented through programmable ROADMs. The results show that significant savings in switching modules and energy can be attained by exploiting the flexibility inherent in programmable ROADM through a proper network design.

Place, publisher, year, edition, pages
IEEE, 2014
National Category
Electrical Engineering, Electronic Engineering, Information Engineering Information Systems
Identifiers
urn:nbn:se:liu:diva-115907 (URN)10.1109/ECOC.2014.6963910 (DOI)
Conference
European Conference on Optical Communication ECOC2014, Cannes, France, September 2014
Available from: 2015-03-23 Created: 2015-03-23 Last updated: 2018-01-11Bibliographically approved
Muhammad, A., Zervas, G., Amaya, N., Simeonidou, D. & Forchheimer, R. (2014). Introducing Flexible and Synthetic Optical Networking: Planning and Operation Based on Network Function Programmable ROADMs. Journal of Optical Communications and Networking, 6(7), 635-648
Open this publication in new window or tab >>Introducing Flexible and Synthetic Optical Networking: Planning and Operation Based on Network Function Programmable ROADMs
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2014 (English)In: Journal of Optical Communications and Networking, ISSN 1943-0620, E-ISSN 1943-0639, Vol. 6, no 7, p. 635-648Article in journal (Refereed) Published
Abstract [en]

Elastic optical networks are envisaged as promising solutions to fulfill the diverse bandwidth requirements for the emerging heterogeneous network applications. To support flexible allocation of spectrum resources the optical network nodes need to be agile. Among the different proposed solutions for elastic nodes, the one based on architecture of demand (AoD) exhibits considerable flexibility against the other alternatives. The node modules in the case of AoD are not hard-wired, but can be connected/disconnected to any input/output port according to the requirements. Thus, each AoD node and the network (fabricated with AoD nodes) as a whole acts like an optical field-programmable gate array. This flexibility inherent in AoD can be exploited for different purposes, such as for cost-efficient and energy-efficient design of the networks. This study looks into the cost-efficient network planning issue for synthetic networks implemented through AoD nodes. The problem is formalized as an integer linear programming formulation for presenting the optimal solution. Furthermore, a scalable and effective heuristic algorithm is proposed for cost-efficient design, and its performance is compared with the optimal solution. The designed networks with AoD nodes are further investigated for a dynamic scenario, and their blocking probability due to limited switching resources in the nodes is examined. To alleviate the blocking performance for the dynamic case, an efficient synthesis strategy along with a scheme for optimal placement of switching resources within the network nodes is presented. Extensive results show that 1) even at high loads, the network with AoD nodes achieves saving of switching modules up to 40% compared to the one with static reconfigurable optical add-drop multiplexers (ROADMs) through a proper network design, 2) by diminishing the spectrum selective switches the overall power consumption of the network decreases by more than 25% for high loads, and 3) for the dynamic scenario the blocking owing to the node modules constraint is alleviated significantly by slightly augmenting the switching devices and optimally deploying them within the network nodes.

Place, publisher, year, edition, pages
Institute of Electrical and Electronics Engineers (IEEE), 2014
Keywords
Architecture on demand; Dynamic traffic; Energy-efficient; Flexible and synthetic optical networks; Network planning; Optical cross-connect; Routing and spectrum allocation
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-109232 (URN)10.1364/JOCN.6.000635 (DOI)000338924800006 ()
Available from: 2014-08-12 Created: 2014-08-11 Last updated: 2017-12-05Bibliographically approved
Ajmal, M., Zervas, G., Simeonidou, D. & Forchheimer, R. (2014). Routing, Spectrum and Core Allocation in Flexgrid SDM Networks with Multi-core Fibers. In: 2014 INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING: . Paper presented at 18th International Conference on Optical Network Design and Modeling (ONDM) (pp. 192-197). IEEE
Open this publication in new window or tab >>Routing, Spectrum and Core Allocation in Flexgrid SDM Networks with Multi-core Fibers
2014 (English)In: 2014 INTERNATIONAL CONFERENCE ON OPTICAL NETWORK DESIGN AND MODELING, IEEE , 2014, p. 192-197Conference paper, Published paper (Refereed)
Abstract [en]

Space division multiplexing (SDM) over multi-core fiber (MCF) is advocated as a promising technology to overcome the capacity limit of the current single-core optical networks. However, employing the MCF for flexgrid networks necessitates the development of new concepts, such as routing, spectrum and core allocation (RSCA) for traffic demands. The introduction of MCF in the networks mitigates the spectrum continuity constraint of the routing and spectrum assignment (RSA) problem. In fact cores can be switched freely on different links during routing of the network traffic. Similarly, the route disjointness for demands with same allocated spectrum diminishes to core disjointness at the link level. On the other hand, some new issues such as the inter-core crosstalk should be taken into account while solving the RSCA problem. This paper formulates the RSCA network planning problem using the integer linear programming (ILP) formulation. The aim is to optimally minimize the maximum number of spectrum slices required on any core of MCF of a flexgrid SDM network. Furthermore, a scalable and effective heuristic is proposed for the same problem and its performance is compared with the optimal solution. The results show that the proposed algorithm is able to well approximate the optimal solution based on ILP model.

Place, publisher, year, edition, pages
IEEE, 2014
Keywords
Space division multiplexing (SDM); multi-core fiber (MCF); inter-core crosstalk; network planning; flexgrid networks
National Category
Electrical Engineering, Electronic Engineering, Information Engineering
Identifiers
urn:nbn:se:liu:diva-112320 (URN)000343647500033 ()978-3-901882-60-9 (ISBN)
Conference
18th International Conference on Optical Network Design and Modeling (ONDM)
Available from: 2014-11-24 Created: 2014-11-24 Last updated: 2015-03-23
Muhammad, A. & Forchheimer, R. (2013). Efficient Scheduling Strategies for Dynamic WDM Networks with Set-Up Delay Tolerance. In: : . Paper presented at 15th International Conference on Transparent Optical Networks (ICTON 2013), 23-27 June 2013, Cartagena, Spain (pp. 1-4). IEEE
Open this publication in new window or tab >>Efficient Scheduling Strategies for Dynamic WDM Networks with Set-Up Delay Tolerance
2013 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Emerging, on-demand applications (e.g., ultra-high definition TV, grid computing, e-health, digital cinema, etc.) will dominate the next generation optical networks. Dynamic on-demand provisioning of optical channels is advocated as a promising solution to fulfil the high bandwidth requirements of these applications. Among the various on-line strategies proposed to provision such applications, the ones exploiting the connection holding-time knowledge and the flexibility provided by the set-up delay tolerance exhibited a good potential in improving the overall network blocking performance. Considering the fact that the users are willing to wait for provisioning until their set-up delay tolerance expire, it is not of prime importance to establish connection on the earliest available resources. Rather, effective results in terms of network blocking performance can be achieved by provisioning connections on optimal instead of earliest available resources that exist within the set-up delay tolerance. This paper presents novel connection scheduling strategies that efficiently exploit the set-up delay tolerance and holding-time knowledge for dynamic wavelength division multiplexing (WDM) networks. The proposed scheme computes the set of all available provisioning opportunities (at different time instants) within set-up delay tolerance and selects the one that is most efficient in terms of network resource utilization. This scheme is investigated for two different scenarios, that are, for connection requests that cannot be provisioned at the time of their arrival due to resource unavailability and for every request irrespective of whether the required resources for set-up are available or not. Simulation results confirm that the proposed strategies attain significant improvement in network blocking probability compared to earlier presented techniques.

Place, publisher, year, edition, pages
IEEE, 2013
Keywords
connections holding-time; dynamic connection provisioning; dynamic scheduling; set-up delay tolerance; WDM networks
National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-106304 (URN)10.1109/ICTON.2013.6602883 (DOI)000333178300210 ()978-147990682-6 (ISBN)
Conference
15th International Conference on Transparent Optical Networks (ICTON 2013), 23-27 June 2013, Cartagena, Spain
Available from: 2014-05-06 Created: 2014-05-05 Last updated: 2014-12-03Bibliographically approved
Ajmal, M., Cavdar, C., Wosinska, L. & Forchheimer, R. (2013). Trading Quality of Transmission for Improved Blocking Performance in All-Optical Networks. In: Asia Communications and Photonics Conference 2013: . Paper presented at Asia Communications and Photonics Conference, November 12-15, Beijing, China (pp. AF4E.5).
Open this publication in new window or tab >>Trading Quality of Transmission for Improved Blocking Performance in All-Optical Networks
2013 (English)In: Asia Communications and Photonics Conference 2013, 2013, p. AF4E.5-Conference paper, Published paper (Refereed)
Abstract [en]

We propose a connection provisioning strategy in dynamic all-optical networks, which exploit the possibility to allow a tolerable signal quality degradation during a small fraction of holding-time resulting in a significant improvement of blocking performance.

Keywords
All-optical networks; Networks, network optimization; Networks, wavelength routing
National Category
Computer and Information Sciences Computer Sciences
Identifiers
urn:nbn:se:liu:diva-115903 (URN)978-1-55752-989-3 (ISBN)
Conference
Asia Communications and Photonics Conference, November 12-15, Beijing, China
Note

DOI does not work: 10.1364/ACPC.2013.AF4E.5

Available from: 2015-03-23 Created: 2015-03-23 Last updated: 2018-03-09Bibliographically approved
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