A graph coloring approach for scheduling undo actions in self-organizing networks

Abstract

In a mobile Self-Organizing Network (SON) a coordinator is necessary to avoid the execution of conflicting SON function instances. Typically, such a coordinator bases its decision to accept or reject a network parameter change request on a rule set that considers only known conflicts. Moreover, it does not observe the impact of approved changes on the network. For this reason, SON verification approaches have been specified to assess the impact of deployed configuration changes and identify those that are causing an undesired network behavior. Similarly to anomaly detection techniques, a SON verification mechanism has a mathematical model that specifies how the network behavior should look like and defines any behavior that significantly deviates form the expectations as abnormal. Furthermore, the outcome is a corrective action, also called an undo action, that sets network parameters to some previous configuration.The question that often remains unanswered is how conflicting undo actions should be scheduled. A SON coordinator does not have the knowledge to resolve them and may, therefore, prevent such from being deployed. In this paper we present a scheduling approach of such undo actions that uses minimum graph coloring in order to identify the sets of cells whose configuration can be safely rolled back. Our evaluation is split in two parts. In the first part we highlight the importance of our approach by observing a real Long Term Evolution (LTE) network. The second part is based on simulation data in which we show the ability of our method to keep the performance of the network at a high level.

Network Element Stability Aware Method for Verifying Configuration Changes in Mobile Communication Networks

“…It determines, which CM changes have an overlapping impact areas with the verification area, and can thus have contributed to the degradation, and creates an undo request for them. Several methods have been developed to optimize the selection of undo areas and requests [15] 3 Challenges Many SON functions require not only one step, but several, during which they observe whether they have moved closer towards achieving their goal. In the process, the functions may induce a transient performance decrease in the network.…”

“…Also, the longer observation window, the more difficult it becomes to find out which changes have actually caused a degradation, especially if there are several parallel changes made by more than one SON function instances. Yet one more problem with a long observation window is that as it makes the verification process longer, it increases the number of parallel verification operations, which can lead to conflicts between them [15]. This can be problematic, especially in more complex networks.…”

“…To evaluate the behavior of SON coordination and verification concepts, we have developed the SON Simulation System (S3), as presented in [15].…”