Invited Session Fri.1.H 3503

Friday, 10:30 - 12:00 h, Room: H 3503

Cluster 23: Telecommunications & networks [...]

Robust and survivable network design


Chair: Fabio D'Andreagiovanni



Friday, 10:30 - 10:55 h, Room: H 3503, Talk 1

Christian Raack
Cutset inequalities for robust network design


In order to create and operate resource- and cost-efficient networks the uncertainty of traffic demand (data, passengers) has to be taken into account already in the strategic capacity design process. A promising approach is robust optimization (RO).
Network design problems in telecommunications or public transport
are often solved using Mixed Integer Programming (MIP) models based on
multi-commodity-flow formulations. It is known that the solution
process can be sped up if strong valid inequalities based on network cuts, so-called cutset inequalities, are used as cutting planes.
In this work, combining methods from RO and MIP, we study the impact of cutset inequalities in solving robust network design problems.
We assume that traffic demands are given as a polyhedral set and
present facet proofs for different variants of these inequalities in
different variable spaces thereby generalizing the deterministic single scenario case. We show that robust cutset inequalities are independent of the chosen recourse scheme (static or dynamic routing). We also report on computational tests showing a significant speed-up for standard solvers such as CPLEX.



Friday, 11:00 - 11:25 h, Room: H 3503, Talk 2

Agustin Pecorari
Models for p-cycle networks design without cycle enumeration

Coauthor: Irene Loiseau


A major issue for telecommunication networks is to be cost efficient with a high level of quality of service. A network is said survivable if it is operational even if certain component fails, that is, if it is still able to provide communication between sites it connects. Mesh restoration schemes were widely used in the 1970s and early 1980s. Ring based topologies were introduced in the late 80s based on self-healing rings (SHR) networks technology. Around ten years later appeared the p-cycle networking concept. A single unit capacity p-cycle is a cycle composed of one spare channel on each span it crosses. So a p-cycle provides one protection path for a failed span and it also protects spans that have both end nodes on the cycle but are not themselves on the cycle. The problem we deal with may be seen as the problem of covering with p-cycles all the demands on a 2-connected graph minimizing the total cost. We propose four new compact ILP and MIP models for this problem. They were tested in standard benchmark cases and on a set of networks representing real USA telecommunications networks. Results were competitive with those of previous work and in several cases improved them.



Friday, 11:30 - 11:55 h, Room: H 3503, Talk 3

Di Yuan
Cell load coupling in planning and optimization of LTE networks

Coauthor: Iana Siomina


This presentation considers a system model that characterizes the coupling relation among cell load levels in Orthogonal frequency division multiple access for long term evolution (LTE) broadband mobile networks. The model takes into account non-uniform traffic demand and the load-dependent interference. Solving the system model enables a network-wide performance evaluation in terms of resource efficiency. We provide a summary of the key mathematically properties of the model. The properties allow for designing powerful means for performance assessment in network planning and optimization. The theoretical insights are accompanied by an illustration of applying the model in load balancing of heterogeneous LTE networks via range optimization of pico-cells.


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