A method and a device for optimizing the assignation of network activity of a cellular communications network to land areas in a simple and accurate way. This technique allows representing the activity of a cellular network on a set of tiles in a grid covering a certain land area, instead of representing it associated to antenna cells that might or might not overlap. The activity dispersed and assigned to non-overlapping grid tiles is much simpler and clearer to understand and allows visualizing how the network activity is distributed over the space and how it varies along time allowing therefore an efficient network design and management optimization.