Near-Optimal Robust Virtual Controller Placement in 5G Software Defined Networks

Ehsan Tohidi, Saeedeh Parsaeefard, Mohammad Ali Maddah-Ali, Babak Hossein Khalaj, Alberto Leon-Garcia

Research output: Contribution to journalArticlepeer-review

6 Scopus citations


Fifth generation (5G) wireless networksare characterized by applying the software defined networking (SDN) and network function virtualization (NFV) concepts to provide higher reliability and scalability, and lower latency for advent data-hungry services. In the initial version of SDN based 5G, a centralized architecture for SDN controller has been proposed, which inherently cannot fulfill those requirements simultaneously. This observation has led us toward distributed architectures, where multiple SDN controllers across the network constitute the control layers. Furthermore, to fully achieve the network flexibility and agility offered by SDN, and also improve resource utilization and consequently to reduce network cost, we incorporate virtualized SDN (vSDN) controllers, enabled through the NFV technology. In vSDN with distributed architecture, controller placement is one of the main challenges, which is an NP-hard combinatorial optimization problem with conflicting objectives: 1) maximizing the reliability of network with low latency; 2) minimizing the total cost of implementation, which can be interpreted as reducing the number of vSDN controllers. In order to achieve such a compromise, in this work, we formulate the problem of vSDN controller placement and introduce some performance metrics to model the latency of communication between controller-switch pairs and also robustness against vSDN controller failures in a network. The introduced formulation is some sorts of submodular optimization, which is exploited to develop several algorithms. Simulations results demonstrate that, with a negligible performance loss, a significant reduction in the number of vSDN controllers is achievable. Finally, latency, cost, and robustness trade-offs are investigated.

Original languageEnglish (US)
Article number9387156
Pages (from-to)1687-1697
Number of pages11
JournalIEEE Transactions on Network Science and Engineering
Issue number2
StatePublished - Apr 1 2021
Externally publishedYes

Bibliographical note

Funding Information:
Manuscript received March 18, 2020; revised November 23, 2020; accepted January 7, 2021. Date of publication March 25, 2021; date of current version July 7, 2021. B. Hossein Khalaj work was supported in part by a grant from the Institute for Research in Fundamental Sciences (IPM). Recommended for acceptance by Prof. Falko Dressler. (Corresponding author: Ehsan Tohidi.) Ehsan Tohidi is with the Department of Telecommunication Systems, Technical University of Berlin, 10623 Berlin, Germany (e-mail: [email protected]).

Publisher Copyright:
© 2013 IEEE.


  • 5G
  • robustness
  • submodularity
  • VSDN controller placement


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