Comparing Online and Offline SON Solutions for Concurrent Capacity and Coverage Optimization

Self-organizing networks (SONs) can carry out their optimization procedures in an on- or off-line manner. On one hand, an online SON solution optimizes network parameters during operation. On the other hand, an offline SON solution employs a simulation environment of the network to be optimized in order to perform an offline parameter optimization before applying changes to the network. Thus far, researchers have not yet compared the characteristics of on- and offline SON solutions and they typically do not comment their SON solution´s operational mode. However, specifying the SONs operational mode is crucial because it determines the type and number of measurements to be performed, and it decides whether it is required to accurately model the network to be optimized or not. In this work, we compare the general properties of on and off-line SON solutions qualitatively and compare an on and an off-line algorithm for coverage and capacity optimization quantitatively, using a realistic LTE simulation scenario. Based on the results obtained, we can conclude that offline SON solutions should be preferred as long as the required inputs are available. However, online SON solutions provide an adequate alternative to offline SON solutions if some of the inputs required are missing.