The network packing problem in terrestrial broadcasting

The introduction of digital terrestrial broadcasting all over Europe requires a complete and challenging replanning of in-place analog systems. However, an abrupt migration of resources (transmitters and frequencies) from analog to digital networks cannot be accomplished because the analog services must be preserved temporarily. Hence, a multiobjective problem arises, in which several networks sharing a common set of resources have to be designed. This problem is referred to as the network packing problem. In Italy, this problem is particularly challenging because of a large number of transmitters, orographical features, and strict requirements imposed by Italian law. In this paper, we report our experience in developing solution methods at the major Italian broadcaster Radiotelevisione Italiana (RAI S.p.A.). We propose a two-stage heuristic. In the first stage, emission powers are assigned to each network separately. In the second stage, frequencies are assigned to all networks so as to minimize the loss from mutual interference. A software tool incorporating our methodology is currently in use at RAI to help discover and select high-quality alternatives for the deployment of digital equipment.