Planning and Provisioning Strategies for Optical Core Networks

Detta är en avhandling från Linköping : Linköping University Electronic Press

Sammanfattning: 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.